J Therm Anal Calorim (2017) 127:1319–1337
DOI 10.1007/s10973-016-6004-7
The investigations of thermal behavior, kinetic analysis,
and biological activity of trinuclear complexes prepared ONNO-
type Schiff bases with nitrito and nitrato l-bridges
Nurcan Acar1 • Orhan Atakol1 • Şaziye Betül Sopacı2 • Demet Cansaran Duman3 •
Ingrid Svoboda4 • Sevi Öz2
Received: 3 July 2016 / Accepted: 25 November 2016 / Published online: 20 December 2016
 Akadémiai Kiadó, Budapest, Hungary 2016
Abstract By using bis-N,N0(salicylidene)-1,3-diamino- concluded that the complexes prepared with reduced Schiff
propane and reduced form of this ligand bis-N,N0(2-hy- bases are more strained structures. Biological activities of
droxybenzylidene)-1,3-diaminopropane, we prepared eight these complexes were also inspected, and antibacterial and
trinuclear complexes in the core form of NiII–NiII–NiII and antifungal activities were tested against four different
NiII–CuII–NiII. Complexes have been characterized with bacterial strains (E. coli, P. aureginosa, S. aureus and E.
element analysis, IR spectroscopy and NMR spectroscopy feacalis) and a fungus species (C. albicans).
methods and also investigated with Thermogravimetry
(TG). It was observed that thermal characteristics of the Keywords Reduced Schiff base  Trinuclear complex 
complexes prepared by the reduced form of Schiff base are Isothermal and non-isothermal kinetic  Ozawa method 
different from complexes prepared by the Schiff base. OFW  Coats–Redfern method
According to TG, two thermal reactions between 120 and
180 C endothermic separation of coordinative dimethyl-
formamide molecules and then around 300 C exothermic Introduction
decomposition of molecule were observed for Schiff base-
prepared complexes. On the other hand, the complexes Bis-N,N0(salicylidene)-1,3-diaminopropane (LH2) and their
resulted from reduced Schiff base reactions were shown derivatives are very inclined ligands to give polynuclear
decomposed around 250–270 C by exothermic thermal complexes; since 1990, there are number of homo and
reaction. Kinetic parameters of decompositions were hetero polynuclear complexes prepared with these ligands
determined by isothermal and non-isothermal kinetic and were reported in the literature [1–25]. During the
methods, Coats–Redfern (CR), Ozawa, Ozawa–Flynn– formation of these polynuclear complexes, acetate
Wall (OFW) and Kissenger–Akahira–Sunose (KAS). [2–10, 21, 22], chloride [11], azide, formate [15–18],
Departing from these values, thermodynamic parameters benzoate [18], nitrite [19] and nitrate [17, 20] anions
were calculated and the results were interpreted. It was constitute l-bridge. The structure of the coordination
sphere of the terminal and central metal ions is different in
trinuclear complexes. Terminal metal ions are located in
& Sevi Öz between two nitrogen of LH2 ligand, two phenolic and one
sevioz@hotmail.com
solvent molecule oxygen and anion in the environment
1 Department of Chemistry, Faculty of Science, Ankara (acetate, format, benzoate, nitrite or nitrate) having a
University, 06100 Ankara, Turkey coordination sphere as N2O4 form; however, central metal
2 Department of Chemistry, Faculty of Science and Arts, Ahi ions formed coordination between four phenolic oxygen
Evran University, 40100 Kırşehir, Turkey and oxygen of anion in the environment and have O6
3 Biotechnology Institute, Ankara University, 06100 Ankara, coordination sphere [5–10]. Trinuclear complexes can be
Turkey prepared by two different ways by using Schiff bases.
4 Strukturforschung, FB Materialwissenschaft, TU- Darmstadt, First of them is template synthesis method. According to
Petersenstrasse 23, 12 64287 Darmstadt, Germany this method, ligand, metal ions and combining anion are
123
1320 N. Acar et al.
reacted in a proper solvent sample such as DMF, DMSO or complexes were prepared by template synthesis and
in dioxane media and trinuclear complexes are obtained as examined by thermogravimetry. In these complexes, nitrite
a result, [21–25]. and nitrate auxiliary anions were used as l-bridge. There
The second method consists of two steps. LH2 and are some examples for trinuclear complexes prepared by
mononuclear NiL complex could be formed by interacting using these anions in the literature, and in these reports,
nickel salts, and then, trinuclear complex could be syn- structures of l-bridges made by nitrite and nitrate anions
thesized with this mononuclear complex in DMF, DMSO were determined [15–18, 20]. While nitrite anion is con-
or dioxane as solvent, [16, 23]. nected to terminal metal ion over oxygen, it is also con-
Schiff bases could be easily reduced in amphiprotic nected to central metal ion over nitrogen ion; nitrate anion
solvents with the help of NaBH4 [21–23]. In consequence is connected to terminal metal ion by oxygen and con-
of reducing imine, nitrogen groups could be transformed nected to central metal ion with second oxygen. The
into secondary amine groups and phenol–amine ligands are complexes prepared in this study were not obtained as
obtained from phenol–imine-type ligands, Fig. 1. proper crystals, but a similar structure, which was prepared
So far, it is not possible to prepare a mononuclear to show the coordination of the nitrate ion, is included in
complex with reduced ligands and a NiLH stoichiometry this study. This complex was prepared by bis-N,N0(2-hy-
complex was not isolated. For that reason, two-step syn- droxyacetophenone)-1,3-propanediamine (LACH2) and
thesis of these complexes with reduced Schiff bases is not added to this study in order to show l-bridges of nitrate
possible. By using reduced Schiff bases, trinuclear com- ion. The total formulas of prepared complexes are shown
plexes were obtained by template synthesis, [21–25]. below, and structures are shown in Fig. 2.
Taking into account iminic nitrogens are converted to
amines, electron density of the nitrogens should increase in
the reduced ligand. Therefore, easier synthesis of Complexes prepared by Schiff bases
mononuclear Ni(II) complexes was expected. There are {[DMFNiLCu(NO2)2NiLDMF]1/2DMF} (I)
many proper dealings related with the complex formation {[DMFNiLCu(NO3)2NiLDMF]DMF} (II)
using the above Schiff base compound and its reduced [DMFNiLNi(NO2)2NiLDMF] (III)
states. Structural analysis of the Schiff base complex {[DMFNiLNi(NO3)2NiLDMF]2DMF} (IV)
reveals 10–18 angle between the metal ion-two iminic {[DMFNiLACCu(NO3)2NiLACDMF]DMF} (V)
nitrogen and two iminic nitrogen—bonded carbon atoms Complexes prepared with reduced Schiff bases
H H
planes. In the reduced state, this angle is 35–40 [26, 27]. [DMFNiL Cu(NO2)2NiL DMF] (VI)
H H
Ideally, this angle is around 62. Under these circum- [DMFNiL Cu(NO3)2NiL DMF] (VII)
H H
stances, the reduced Schiff base complex is expected to be [DMFNiL Ni(NO2)2NiL DMF] (VIII)
H H
more stable, but a stable mononuclear complex was not [DMFNiL Ni(NO3)2NiL DMF] (IX)
isolated. To explain this, thermogravimetrical analysis was
employed and many reports have been published related
with TG analysis of trinuclear complexes prepared with
Schiff bases [18, 28]. To investigate the strain possibility of these two com-
In these researches, it was clearly observed that DMF plex groups, we examined them by thermogravimetric
molecules connected to terminal groups were separated methods. Although complexes in these two groups are in
from structure as thermally and mass losses gave signifi- similar structures, their thermo gravimetric curves were
cant results in characterization of complexes. But this mass significantly different from each other. Activation energy
loss related to the DMF’s separation was not observed in and other thermodynamic parameters were calculated by
reduced Schiff bases. In order to explain this situation, by isothermal and non-isothermal thermokinetic methods and
using nitrite and nitrate-bridged anions with LH ligand compared. Activation energy was expected to be smaller in2
four complexes and with LHH ligands, four trinuclear strained complexes, for that reason more than one methods2
Fig. 1 Bis-N,N0(salicylidene)- H
1,3-propanediamine ligand’s HH H   NaBH4
reduction reaction C N N C  in MeOH C N N C
H H H H
OH H O OH H O
       LH         L
HH2
2
phenol–imin phenol–amine
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1321
Fig. 2 Structures of the
CH3
prepared complexes H CH3 H
C N C N
O CH O3 CH3
H H H
H
C N N C C N N C
Ni Ni
O O O O
O O O O
N M O N M N O
N
O O
O O
O O O O
Ni Ni
C N N C C N N
C
H H HH
H C H3C3 O O
N C N C
H3C H H3C H
M=Cu(II)  (I) M=Cu(II)  (II)
M=Ni(II)   (III) M=Ni(II)   (IV)
H CH3 H CH3
C N C N
O CH3 O CH3
H H H H
C NH HN C C NH HN C
H H H H
Ni Ni
O O O O
O O
O O
N
M O N M N ON
O O
O O
O O O O
Ni Ni
H H H H
C NH HN C C NH HN C
H H H H
H3C O H3C O
N C N C
H3C H H3C H
M=Cu(II)  (VI) M=Cu(II)  (VII)
M=Ni(II)   (VIII) M=Ni(II)   (IX)
123
1322 N. Acar et al.
were used for calculation. Since it is possible to direct X-ray crystallography
calculation of activation energy from thermo gravimetry
curves employing Ozawa equation with a software, TA60 A single crystal of [DMFNiLACCu(NO3)2NiLACDMF]
Version 2.01 of the device that we used, we preferred to (complex V) was analyzed on an Oxford Diffraction
use Ozawa method first [29, 30]. But due to explosive Xcalibur single-crystal X-ray diffractometer with a sap-
effects of nitrite and nitrate ions in higher temperatures, phire CCD detector using MoKa radiation
Ozawa method did not give any result for explosive (k = 0.71073 A) operating in x/2h scan mode. The unit-
exothermic reactions. For that reasons, non-isothermal cell dimensions were determined and refined by using the
kinetic methods Ozawa–Flynn–wall [31–35] and Kissen- angular settings of 25 automatically centered reflections in
ger–Akahira–Sunose [33–37], and as isothermal method 2.85 B h B 228.24 range. The data of the complex V
Coast–Redfern [38, 39] were employed manually and were collected at 100(2) K. The empirical absorption cor-
thermokinetic results were obtained. rections were applied by the semi-empirical method via the
In the scope of this study, we also investigated biolog- CrysAlis CCD software [40]. The model was obtained from
ical activity of these complexes split into two different the results of the cell refinement, and the data reductions
groups to compare the influence of different structures to were carried out using the solution software SHELXL97
their bioactivity, in consistent with the literature [38, 39]. [41]. The structure of the complex V was determined by
Biological activities were determined on seven complexes. direct methods using the SHELXS-97 software implemented
Behaviors of these complexes in DMF solution were in the WinGX package [42]. Supplementary material for
assessed against gram-negative bacteria Echericia coli and structure has been deposited with the Cambridge Crystal-
Pseudomonas aurogines and against gram-positive bacteria lographic Data Center as CCDC no: 1481757 (de-
Staphilococcus aureus and Entorococcus feacalis and a posit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
fungus Candida albicans. Minimum Inhibitory Concen-
tration (MIC) values were determined for the eight Biological activity of the complexes
complexes.
Microbial strains
Experimental In the examined study, microorganisms were selected to
include gram-positive bacteria (Staphylococcus aureus
Materials and apparatus ATCC 25923 and Enterococcus feacalis RSKK 508),
gram-negative bacteria (Pseudomonas aeruginosa ATCC
Used reactives were of Merck or Fluka brands, and they 9027 and E. Coli ATCC 35218) and yeast (Candida albi-
were used without further purification. In this study, Shi- cans ATCC 10231). All the strains were stored at -20 C
madzu Infinity FTIR spectrometer equipped with three in tryptic soya broth (TSB; Oxoid, Basingstoke, UK) with
reflectional ATR units was used for IR spectra with 4 cm-1 20% glycerol.
accuracy. The C, H and N analyses were performed on The inocula of microorganism strains were prepared
Eurovector 3018 C,H,N,S analyzer. Metal analyses were from an overnight culture for bacteria in Muller–Hinton
recorded on GBC Avanta PM Model atomic absorption agar, whereas Sabouraud agar was used for growing the
spectrometer using FAAS mode. Complex (2–3 mg) was fungi. The suspensions were adjusted to 0.5 McFarland for
8
dissolved in 1 mL HNO3 (63%) with heating, diluted to the turbidity (1 9 10 colony-forming units [CFU]/mL).
100 mL and given to nebulizer of atomic absorption
spectroscopy for metal analysis. The mass spectra of the Antibacterial and antifungal test
ligands were obtained by Shimadzu, 2010 plus with direct
inlet (DI) unit with an electron impact ionizer. DI tem- The antimicrobial activity of the synthesized chemicals was
perature was varied between 40 and 140 C, and ionization assayed for the microdilution method, which determines the
was done with electrons with 70 eV energy. The NMR minimum inhibitory concentration (MIC) leading to the
spectra were recorded on the Bruker Ultrashield 300 MHz inhibition of bacterial growth. The composites in dispersion
NMR spectrometer. DMSO-d6 solution was the solvent. form were diluted 2–128 times with 100 mL of Mueller–
The thermogravimetric analyses were performed by Shi- Hinton broth inoculated with the tested bacteria at a con-
5
madzu DTG 60H. In thermogravimetric analyses, temper- centration of 19 10 CFU/mL. The MIC was read after 24 h
ature was varied between 30 and 600 C. These analyses of incubation at 37 C as the MIC of the tested substance that
were performed at 5, 10, 15, 20 and 25 C/min rates and inhibited the growth of the bacterial strain. The dispersions
under N2 atmosphere in Pt pans. Calibration of the were used in the form in which they had been prepared.
instrument was done with metallic In and Pb. Therefore, control bactericidal tests of solutions were
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1323
performed containing all the reaction components. Saturated benzaldehyde (0.1 mol, 12.20 g) was dissolved in 120 cm3
stock solutions of the extracts were prepared in DMSO. of warm EtOH; then, 0.05 mol (3.70 g) of 1,3-diamino-
Double serial dilutions were also prepared in the same sol- propane was added to this solution and heated up to the
vent. Aliquots of the solutions (1 mL) were mixed with a boiling point. After cooling, yellow crystals were filtered
fixed amount of molten Muller–Hinton agar at 45 C to get and dried in air. Yield: 90–95%, mp: 58 C (determined by
the final concentrations. When the agar solidified, the plates TG).
were inoculated with 10 lL microbial suspension (19 106
CFU/mL). The inoculated plates were incubated for 24 h at Elemental analysis for C17H18N2O2
35 C for bacteria and for 48 h for the yeast. Each of the
chemicals (0.312, 2.5, 1.25, 0.625 and 0.312 mg) were added Anal. Calcd. %: C 72.32; H 6.43; N 9.92.
in the plates. Positive controls for all microorganisms were
Found %: C 71.95; H 6.33; N 10.09.
prepared using 1 mL DMSO instead of an extract solution.
After incubation, the plates were inspected visually. MIC was Important IR data (cm-1): mO–H: 2627, mC–H(Ar):
recorded as the lowest concentration at which no visible 3021–3019, mC–H(Aliph): 2929–2862, mC=N: 1629, mC=C(ring):
growth of the test pathogens was observed. The test was not 1608, mC–O(Phenol): 1274–1151, dC–H(Ar): 762.
considered valid unless the positive controls showed signifi- Kmax = 243 nm, e = 7045 dm
3 mol-1 cm-1 in DMSO,
cant microbial growth. Standard antibiotic (amoxicillin) were kmax = 242 nm, e = 7865 dm
3 mol-1 cm-1 in MeOH.
used to control the sensitivity of the tested bacteria, and 1HNMR data in d -DMSO(d, ppm): 13.51 (s) (O–H),
amphotericin B was used as controls against the tested fungi. 6
8.60 (s) (–CH=), 7.43 (d) (HAr), 7.32 (t) (HAr), 6.88
(t) (HAr), 3.68 (t) (N–CH2–), 2.01 (p) (–CH2–), Fig. 3.
Preparation of the ligands 13CNMR data in d6 DMSO(d, ppm): 166.6 (–C=N),
161.1, 132.7, 132.1, 119.1, 118.9 116.9 (C ), 58.5 (N–
Preparation of N,N-bis (2-hydroxyphenylidene)-1,3- Ar
CH –), 31.9 (–CH –), Fig. 4.
propanediamine (LH2)
2 2
MS m/z: 282 [M]?, 161 [HO–C6H4–CH=N–CH2–CH2–
This Schiff base was prepared via condensation reaction in CH ?2] , 148 [HO–C6H4–CH=N–CH2–CH
?
2] (Basepeak),
EtOH under hydrothermal conditions using 2-hydroxy- 134 [HO–C ?6H4–CH=N–CH2] , 120 [HO–C
?
6H4–CH=N] ,
benzaldehyde and 1,3-diaminopropane. 2-Hydroxy- 107 [HO–C ?6H4–CH2] , 77 [C
?
6H5] , Fig. 5.
13 12 11 10 9 8 7 6 5 4 3 2 1 0 –1 ppm
Fig. 3 1HNMR spectrum of LH2
220 200 180 160 140 120 100 80 60 40 20 0 ppm
Fig. 4 13CNMR spectrum of LH2
123
1324 N. Acar et al.
%
100 148
75
50 282
25 10777 162
41 197 239 316 3380 647
50 100 150 200 250 300 350 400 450 500 550 600 650
Fig. 5 MS fragments of LH2 obtained using DI equipment
13 12 11 10 9 8 7 6 5 4 3 2 1 0 –1 ppm
Fig. 6 1HNMR spectrum of LHH2
The phenolic hydrogens are observed at 13.51 ppm, the stirring, 300 cm3 of ice water was added to it. The final
iminic hydrogens at 8.60 ppm and aromatic hydrogens at mixture was left to stand for 24 h. After filtration, the white
7.43–6.68 ppm d value in 1HNMR spectrum. As expected precipitate was air-dried. The product bis-N,N0(2-hydroxy-
the aliphatic hydrogens are seen at 3.68 and 2.01 ppm as benzyl)-1,3-propanediamine (LHH2) was recrystallized from
triplet and pentet, respectively. On the other hand, in hot EtOH:H2O (2:1, v/v). Yield: 55–60%, mp: 107 C.
13CNMR spectrum are seen 9 different carbon atoms sig-
nals as expected. It is probable that the signal at 166 ppm Elemental analysis for C17H22N2O2
observed is the signal of iminic carbon atom. The molec-
ular mass of LH2 Schiff base can be seen from the MS Anal. Calcd. %: C 71.30; H 7.74; N 8.01.
spectrum, and the signal at 282 m/z value observed is the
Found %: C 70.86; H 6.69; N 8.37.
molecular peak of LH2.
Important IR data (cm-1): mN–H: 3307, mC–H(Ar):
Preparation of N,N-bis (2-hydroxybenzyl)-1,3- 3055–3023, mC–H(Aliph): 2967–2823, mC=C(ring): 1606–595,
propanediamine (LHH2) mCO(Phenol): 1253–1099, dC–H (Ar): 752.
1
0 H NMR data in d6-DMSO(d, ppm): 7.12 (m), 6.67 (m),3.0 g of bis-N,N (salicylidene)-1,3-propanediamine (LH2)
3 6.83 (broad), 3.80 (m), 2.56 (m), 1.15 (m), Fig. 6.was dissolved in 70.0 cm of MeOH by stirring and heat-
ing. This solution was heated up to 50 C, and to this 13C NMR data in d6-DMSO (d, ppm): 157.64, 128.43,
solution, solid NaBH4 in small portions was added until 127.78, 124.61, 118.34, 115.39 (CAr), 50.80 (Ar–CH2–N),
colorless under strong mixing [31–34]. After 10 min of 46.30 (HN–CH2), 28.94 (CH2–CH2–CH2), Fig. 7.
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1325
220 200 180 160 140 120 100 80 60 40 20 0 ppm
Fig. 7 13CNMR spectrum of LHH2
%
100 107
75 136
50
25 77 148 179
44 57
0 95 180
286
213 241 265 305 338 352 376
50 100 150 200 250 300 350
Fig. 8 MS fragments of LHH2 obtained using DI equipment
MS (m/z): 286 (molecular peak), 179 [HO–C6H4–CH2– 0.05 mol (3.70 g) of 1,3-diaminopropane was added to this
NH–CH2–CH2–CH2–NH]
?, 163 [HO–C6H4–CH2–NH– solution and heated up to the boiling point. After cooling,
CH2–CH2–CH ]
?
2 , 150 [HO–C6H4–CH2–NH–CH2–CH2]
?, yellow crystals were filtered and dried in air. Yield:
136 [HO–C6H4–CH2–NH–CH
?
2] , 122 [HO–C6H4–CH2– 94–96%, mp: 123.6 C (determined by TG).
NH]?, 107 [HO–C H –CH ]?6 4 2 (base peak), 90 [C6H4–
CH ?2] , 77 [C
?
6H5] , Fig. 8. Elemental analysis
As shown in Fig. 6, a broad signal is observed between
Expected % C: 73.52, H: 7.14, N: 9.02; Found % C: 73.09,
aromatic hydrogens signals. This signal is probably from
H: 6.35, N: 8.82.
amine hydrogens. But this signal was not observed in the
diluted solution, whereas the signal of the phenolic
Important IR data (cm-1): m : 3036–3017,
hydrogens was seen at 13.2 ppm d value in diluted solu- C–H(Ar)
m : 2922–2944–2866, m : 1610, m : 1600,
tion. Due to the hydrogen bond formation, the signal of C–H(Aliph) C=N C=C(ring)
mC–O(Phenol): 1232–1159, dC–H(Ar): 754.amine hydrogens is observed as a broad peak. Nine dif-
ferent C atoms signals are observed from the 13CNMR 1HNMR data in d6-CH3COCH3: 13.68 (s), 8.71 (s), 7.45
spectrum. As the iminic double bond is transformed into a (dd), 7.34 (td), 6.91 (t), 3.52 (t), 2.06 (p).
single bond, a signal at 166 ppm around is not observed, 13CNMR data in d-CHCl3: m/z: 310 (MP), 193, 179, 164,despite that to a new signal around 50 ppm. Weak
150, 136, 121 (BP), 107, 91.
molecular peak of the reduced Schiff base is observed at
286 m/z value from the mass spectrum.
Preparation of the complexes
Preparation of N,N-bis (2-hydroxyacetophenilidene)-1,3- As given above, trinuclear complexes can be synthesized
propanediamine (LACH2) by two different methods. The first method is known as
template method. In this method, all reagents are reacted in
This Schiff base was obtained from 2-hydroxyacetophe- the same solvent, Scheme 1.
none and 1,3-diaminopropane in EtOH under hydrothermal The second method occurs in two steps: firstly, a
conditions using. 2-Hydroxyacetophenone (0.1 mol, mononuclear complex is obtained; then, trinuclear complex
13.60 g) was dissolved in 150 cm3 of warm EtOH; then, is synthesized in the second step, Scheme 2.
123
1326 N. Acar et al.
in DMF Important IR data (cm-1): m : 3048–3029,
2LH2 + 3NiX2 DMF·NiL·NiX2·NiL·DMF
C–H(Ar)
mC–H(Aliph): 2924–2873, mC=O(DMF): 1658, mC=N: 1627,
–4HCl
mC=C(ring): 1596, mN=O: 1309, dCH2: 1473, mC–O(Phenol):
   in DMF 1197–1153, dC–H(Ar): 759.
2LHH2 + 3NiX DMF·NiLH2 ·NiX2·NiLH·DMF
–2 HCl Complex II, {[DMFNiLCu(NO3)2NiLDMF]DMF}
X = CH COO– ,  HCOO– , NO – , NO – (C43H53N9O13Ni2Cu)3 2 3
Scheme 1 Direct trinuclear complex formation with Schiff bases or Element analysis: Expected % C: 47.61, H: 4.92, N:
reduced Schiff bases using template synthesis 11.61, % Ni: 10.82, % Cu: % 5.85; Found % C: 47.11, H:
4.59, N: 10.33, Ni: 10.23, Cu: 6.07 (This molecule is
Preparation of the Schiff base complexes (complex included 1 molecule DMF as solvate).
I–IV)
Important IR data (cm-1): mC–H(Ar): 3038–3026,
These complexes are synthesized according to Scheme 2 in mC–H(Aliph): 2922–2845, mC=O(DMF): 1670, mC=N: 1631,
two steps, previously was prepared mononuclear NiL mC=C(ring): 1595, mN=O:1417–1440, dCH2: 1473, mC–O(Phenol):
complex from bis-N,N0(salicylidene)-1,3-propanediamine 1296–1253, dC–H(Ar): 756.
and NiCl26H2O, secondly were prepared trinuclear com-
plexes I–IV using this NiL complex. Complex III, [DMFNiLNi(NO2)2NiLDMF]
(C40H46N8O10Ni3)
Preparation of mononuclear NiL complex
Element analysis: Expected % C: 49.28, H: 4.76, N:
NiL mononuclear complex was prepared as described 11.49, % Ni: 18.06; Found % C: 48.51, H: 4.43, N: 10.85,
according to the literature [43]. A quantity of 0.05 mol Ni: 17.44.
(14.1 g) bis-N,N0(salicylidene)-1,3-propanediamine was Important IR data (cm-1): mC–H(Ar): 3040–3023,
dissolved in 150 mL hot EtOH, and 10 mL concentrated mC–H(Aliph): 2924–2839, mC=O(DMF): 1672, mC=N: 1628,
ammonia was added to this solution. Then, a solution of mC=C(ring): 1595, mN=O: 1309, d CH2
: 1473, mC–O(Phenol): 1195,
0.05 mol (11.80 g) NiCl2 6H2O in 50 mL hot water was dC–H(Ar): 758.
added to this mixture. After setting, the solution was set
aside for 2 h and light green precipitated was filtered and Complex IV, {[DMFNiLNi(NO3)2NiLDMF](DMF)2}
dried in a oven at 140 C for 3–4 h. (C46H60N10O12Ni3)
Preparation of complexes I–IV Elemental analysis: Expected % C: 49.28, H: 5.39, N:
12.48, % Ni: 15.70; Found % C: 48.69, H: 4.91, N: 11.87,
A quantity of 0.002 mol (0.680 g) of the complex NiL was Ni: 151.22, Cu: 6.31 (This molecule is included 2 mole-
dissolved in 50 mL DMF by heating until 110 C. For com- cules DMF as solvate).
plex I 0.001 mol (0.170 g) CuCl22H2O and 0.002 mol
(0.140 g) NaNO , for complex II 0.001 mol (2.41 g) Important IR data (cm
-1): mC–H(Ar): 3044–3027,2
Cu(NO ) 3H O, for complex III 0.001 mol (0.236 g) NiCl mC–H(Aliph): 2922–2862, mC=O(DMF): 1671, mC=N: 1629,3 2 2 2-
2H2O and 0.002 mol (0.140 g) NaNO and for complex IV mC=C(ring): 1595, mN=O: 1400, dCH2: 1473, m2 C–O(Phenol):
0.001 mol (0.291 g) Ni(NO ) 6H O were dissolved in 30 mL 1193–1074, dC–H(Ar): 754.3 2 2
water–MeOH mixture (v/v: %50–%50) using heating and
mixed with the above solution. The resulting mixture was set Preparation of the complex V
aside for 3–4 days in air. After this period, the precipitated
crystals products were filtered and dried in air. The analytical This complex was prepared by template method. A quan-
results of the complexes synthesized are given below. tity of 0.002 mol (0.640 g) bis-N,N
0(2-hydroxyacetophe-
nilidene)-1,3-propanediamine was dissolved in 40 mL
Complex I, [DMFNiLCu(NO ) NiLDMF] DMF by heating. To this solution was added 1.0 mL Et N2 2 3
(C H N O Ni Cu) and a solution of 0.002 mol (0.472 g) NiCl26H2O in40 46 8 10 2
20 mL hot MeOH then finally was added to the mixture a
Element analysis: Expected % C: 49.04, H: 4.73, N: solution of 0.001 mol (2.41 g) Cu(NO3)23H2O in 10 mL
11.43, % Ni: 11.98, % Cu: % 6.49; Found % C: 48.76, H: hot MeOH. The resulting mixture was set aside for 4 days,
4.36, N: 10.95, Ni: 11.29, Cu: 6.31. and the precipitated crystals were filtered and dried in air.
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1327
Scheme 2 Preparing trinuclear in MeOH or EtOH
complex with Schiff bases and LH2 + NiX 2 NiL step 1
mononuclear complexes –2HCl
in DMF
2NiL + NiX2 DMF·NiL·NiX2·NiL·DMF step 2
–2HCl
X = CH3COO– ,  HCOO– , NO2– , NO3–
{[DMFNiLACCu(NO3)2NiLACDMF](DMF)}, Complex VII, [DMFNiLHCu(NO3) NiLH2 DMF],
(C47H61N9O13Ni2Cu) (C40H54N8O12Ni2Cu)
Elemental analysis: Expected % C: 49.49, H: 5.39, N: Elemental analysis: Expected % C: 47.12, H: 5.34, N:
11.05, % Ni: 10.27, Cu: 5.57; Found % C: 47.98, H: 4.75, 10.98, Ni: 11.48, Cu: 6.27; Found % C: 46.59, H: 5.13, N:
N: 10.63, Ni: 9.62, Cu: 5.74. 10.66, Ni: 11.07, Cu: 6.92.
Important IR data (cm-1): mC–H(Ar): 3055–3020, Important IR data (cm
-1): mN–H: 3167–3140, mC–H(Ar):
mC–H(Aliph): 2931–2839, mC=O(DMF): 1672, mC=N:1630, 3043–3021, mC–H(Aliph): 2918–2868, mC=O(DMF): 1658,
mC=C(ring): 1595, mN=O: 1438–1328, dCH2: 1473, mC–O(Phenol): mC=C(ring): 1598, mN=O: 1425–1396, dCH2: 1483, mC–O(Phenol):
1244–1134, dC–H(Ar): 750. 1274–1257, dC–H(Ar): 750.
Preparation of the complexes with reduced Schiff base, Complex VIII, [DMFNiLHNi(NO H2)2NiL DMF],
complex VI–IX (C40H54N8O10Ni3)
These complexes were synthesized by template method Elemental analysis: Expected % C: 48.89, H: 5.54, N:
according to the Scheme 1 and the literature [18, 24, 26, 44]. 11.34, Ni: 11.39; Found % C: 48.53, H: 4.98, N: 11.18, Ni:
A quantity of 0.002 mol (0.572 g) the reduced Schiff base 10.34.
bis-N,N0(2-hydroxybenzyl)-1,3-propanediamine was dis-
Important IR data (cm-1): mN–H: 3186–3144, m :solved in 40 mL DMF under heating and mixed. 1.0 mL C–H(Ar)
 3047–3033, m : 2938–2861, m : 1655,Et3N and a solution of 0.002 mol (0.472 g) NiCl2 6H2O in C–H(Aliph) C=O(DMF)m : 1593, m : 1413–1384, d : 1481, m :
20 mL hot MeOH were added to this solution. Then, for C=C(ring) N=O CH2 C–O(Phenol)
1312–1280, d
complex VI 0.001 mol (0.170 g) CuCl 2H O and C–H(Ar): 756.2 2
0.002 mol (0.140 g) NaNO2, for complex VII 0.001 mol Complex XI, [DMFNiLHCu(NO ) NiLHDMF],
(2.41 g) Cu(NO3)23H2O, for complex VIII 0.001 mol 3 2(C H
(0.236 g) NiCl 2H O and 0.002 mol (0.140 g) NaNO and 40 54N8O12Ni3)2 2 2
for complex IX 0.001 mol (0.291 g) Ni(NO3)26H2O were Elemental analysis: Expected % C: 47.35, H: 5.36, N:
dissolved in 30 mL water–MeOH mixture (v/v: %50–%50)
11.04, Ni: 17.35; Found % C: 46.87, H: 4.88, N: 10.57, Ni:
using heating and mixed with the above mixture. The
16.09.
resulting mixture was set aside for 4–5 days, and after this
period, the crystal products were filtered and dried in air. Important IR data (cm-1): mN–H: 3246, mC–H(Ar):
The analytical results of these complexes are given below. 3036–3017, mC–H(Aliph): 2922–2858, mC=O(DMF): 1652,
mC=C(ring): 1593, mN=O: 1419–1385, dCH2: 1481, mC–O(Phenol):
Complex VI, [DMFNiLHCu(NO2)2NiLHDMF], 1313–1275, dC–H(Ar): 756.
(C40H54N8O10Ni2Cu)
Elemental analysis: Expected % C: 48.64, H: 5.51, N:
Results and discussion
11.34, % Ni: 11.85, Cu: 6.43; Found % C: 47.99, H: 5.08,
N: 10.97, Ni: 11.41, Cu: 5.96.
As mentioned in introduction part, complexes including
Important IR data (cm-1): mN–H: 3169–3143, mC–H(Ar): nitrite and nitrate ions were reported in the literature as l-
3041–3021, mC–H(Aliph): 2924–2858, mC=O(DMF): 1659, bridge [15–18, 20]. Molecular models were determined by
mC=C(ring):1595, mN=O:1425, dCH2: 1483, mC–O(Phenol): X-ray diffraction in literature studies. Nitrate ion links Ni
1284–1259, dC–H(Ar): 748. (II) ions and central metal ions with two oxygen, while
123
1328 N. Acar et al.
nitrite ion is linked to terminal Ni(II) ions with one oxygen Schiff bases, two thermal reactions are observed, and the
links to central metal ion via nitrogen atom. As mentioned ones contained in DMF as solvate, three thermal reactions
above, complex V was synthesized by using a different are observed. On the other hand, complexes prepared by
Schiff base. Purpose of preparing this complex is to show reduced Schiff bases, only one thermal reaction was
the condition of nitrate bridge once again in parallel to the observed. The first mass loss seen on the curves depicted in
literature. For complex V, pluton drawing obtained by red and green colors corresponds to one- and two-molecule
X-ray diffraction works is given in Fig. 9. Crystallographic DMF existing as solvate. Second mass losses in Fig. 10 are
data and experimental data of complex V, and important not clearly seen in the nitrite including complexes; how-
angles and lengths around coordination sphere are given in ever, it can be stated that these mass losses correspond to
Tables 1 and 2, respectively. two coordinative DMF existing in trinuclear complex.
As shown in Fig. 9, terminal ion Ni(II) exists between Similar case can be seen on DTA curves. First endothermic
two phenolic oxygen, two iminic nitrogen and one DMF reactions observed in Fig. 11 belong to DMF molecules
molecule oxygen and one nitrate oxygen O4N2 donor existing as solvate, second endothermic signals belong to
atoms, while central Cu(II) ion exists among four phenolic separation of coordinative DMF molecules and last two
oxygen and two nitrate oxygen in O6 coordination sphere. signals belongs to three thermal reactions of nitrite and
As it can be seen, there are two different l-bridges as nitrate containing complexes. However, in Fig. 13, it is
phonologic oxygen and nitrates-constituted l-bridges. seen that one thermal reaction is exothermic in four
Complexes prepared by LH2 vs L
HH2 are in similar complexes prepared with reduced Schiff base. Thermoan-
structure. Complexes I–V and other complex groups VI–IX alytical data obtained from these curves are given in
were examined by TG, and significant differences were Table 3.
observed between TG curves. In Fig. 10, TG curves of I– As shown in Figs. 10, 11 and Table 3 in Schiff base
IV-numbered complexes are seen in a body, and DTA complexes, the ones containing nitrite, DMF molecules are
curves of these materials are shown in Fig. 11 together. TG separated from structure at 180–200 C. In this case, there
curves of VI–IX-numbered complexes are shown in is only NiL, and nitrite or nitrate salts are remained in the
Fig. 12, and DTA curves of these complexes are shown in environment. It is known that mixture of nitrite and nitrate
Fig. 13. ions in organic material behaves as energetic material in
As shown in Figs. 10 and 12, TG curves of both groups higher temperatures [45]. In this case, residual nitrite or
are different from each other. In complexes prepared by nitrate rapidly oxidizes a part of NiL mononuclear complex
C24 06
C23
025
N5 C15
N4
C19
C25
C13
C11 04 C17
02
05
N2 01
C10 Ni1
C18
C9 C1
03 C2
C8 N1
C7
C6 C20 C3
N3
C5 C22
C4
C21
Fig. 9 {[DMFNiLACCu(NO3)2NiLACDMF]DMF} pluton drawing of complex V. One molecule exists as DMF solvate in crystal structure
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1329
Table 1 Crystallographic and experimental data of complex V Table 2 Selected bond length and angle values around of coordina-
tion sphere
Formula weight/g mol-1 C47H61N9O13Ni2Cu
Bond length/Å Bond angles/
T/K 100 (2)
Crystal size/mm 0.64 9 0.42 9 0.14 N1 Ni1 2.087(5) O4 Ni1 O2 91.69(18)
Crystal system Monoclinic N2 Ni1 2.095(5) O4 Ni1 O1 90.47(17)
Space group P2 N4 O4 1.251(8) O2 Ni1 O1 82.94(16)1/c
a/Å 11.9957 (6) N4 O5 1.273(7) O4 Ni1 N1 93.6(2)
b/Å 15.2470 (7) N4 O25 1.505(10) O2 Ni1 N1 172.48(18)
c/Å 15.5784 (9) O1 Ni1 2.039(4) O1 Ni1 N1 91.63(18)
Alpha 90.00 O1 Cu1 2.069(4) O4 Ni1 N2 94.3(2)
Beta 96.615 (7) O2 Ni1 2.030(4) O2 Ni1 N2 90.68(19)
Gamma 90.00 O2 Cu1 2.052(4) O1 Ni1 N2 172.1(2)
V/Å3 2830.3 (3) O3 Ni1 2.192(5) N1 Ni1 N2 94.3(2)
Z 2 O4 Ni1 2.016(4) O4 Ni1 O3 175.44(17)
Calc. density/g cm-3 1.425 O5 N4 1.273(7) 3 O2 Ni1 O3 92.55(18)
l/mm-1 1.102 O5 Cu1 2.095(4) O1 Ni1 O3 91.71(17)
F (000) 1270 Cu1 O2 2.052(4) N1 Ni1 O3 82.4(2)
T –T 0.5391–0.8611 Cu1 O1 2.069(4) N2 Ni1 O3 84.0(2)min max
h Range/ 2.95–28.24 Cu1 O5 2.095(4) O2 Cu1 O2 180.0(2)
Index ranges -14 B hB13, -18 B kB19, O2 Cu1 O1 81.67(16)
-19 B lB19 O2 Cu1 O1 98.33(16)
Reflections collected 5949 O2 Cu1 O1 98.33(16)
Reflections unique 4249 O2 Cu1 O1 81.67(16)
R1, wR2 (2ó) 0.1092, 0.3248 O1 Cu1 O1 180.0(2)
R1, wR2 (all) 0.1313, 0.3448 O2 Cu1 O5 93.21(17)
Data/parameters 5949/379 O2 Cu1 O5 86.79(17)
GOOF of F2 1.341 O1 Cu1 O5 93.91(16)
Largest difference peak hole/ -1.337, 3.410 O1 Cu1 O5 86.09(16)
e Å-3 O2 Cu1 O5 86.79(17)
CCDC No 1,481,757 O2 Cu1 O5 93.21(17)
O1 Cu1 O5 86.09(16)
O1 Cu1 O5 93.91(16)
and a reaction similar to explosion reaction is observed.
O5 Cu1 O5 180.0(3)
This explosion reaction is observed in nitrate complexes
(complex II and IV) around 330 C and is observed around
280 C in nitrite complexes (complex I and III). This sit- support this suggestion. In complexes prepared by Schiff
uation arises due to possible nitrate and nitrite is coordi- bases, DMF molecules are separated from structure in a
nated from different atoms. While complexes with nitrite certain temperature range around 150–160 C suggesting
are coordinated on oxygen and nitrogen, nitrate complexes that trinuclear complex is decomposed probably, and here,
are coordinated on two oxygen atoms. Same situation is the residual is NiL and nitrate salt. NiL could be prepared
seen on reduced Schiff base complexes. Complexes as mononuclear complex and could be obtained as
including nitrite (complex VI and VIII) give explosion stable form. In reduced Schiff bases because NiL
H is not
reaction around 230 C, and complexes including nitrate stable structure, trinuclear complex can stand up to 250 C
give explosion reaction around 260 C. Mass loss observed and decompose in this temperature with explosion reaction,
in reduced complexes is a little bit higher than Schiff base in this situation mass loss is a little bit higher comparing to
H
complexes. Above-mentioned thermoanalytical data indi- Schiff base complexes. Due to NiL is an unsta-
cate that mononuclear NiLH complex is stable at some ble mononuclear complex, trinuclear complex should be
reduced Schiff base complexes. One NiLH complex could more tensed and unstable compared to Schiff base com-
not be prepared between LHH2 and Ni (II) ion. In spite of plexes. Thermokinetic calculations were done with this
this when LHH2 was used, trinuclear complex was easily consideration. Thermokinetic calculations were performed
prepared by template method. This situation shows LHH2 according to Ozawa [29, 30], Ozawa–Flynn–Wall (OFW)
ligand complexes are stable at trinuclear state. TG results [31–35] and Kissenger–Akahira–Sunose (KAS) [33–37]
123
1330 N. Acar et al.
100 100
80 80
60 60
40 40
20 20
0 0
0 100 200 300 400 500 600 700
Temperature/°C 0 100 200 300 400 500 600 700
Temperature/°C
Fig. 10 TG curves of complexes I–V. Black [DMFNiLCu(NO2)2
NiLDMF] (I), Red {[DMFNiLCu(NO3)2NiLDMF]DMF} (II), Fig. 12 TG curves of complexes VI–IX. Black [DMFNiLH
Blue [DMFNiLNi(NO2)2NiLDMF] (III), Green {[DMFNiL Cu(NO2)2NiLHDMF] (VI), Red [DMFNiLHCu(NO3)2NiLHDMF]
Ni(NO3)2NiLDMF]2DMF} (IV), Pink [DMFNiLACCu(NO3)2 (VII), Blue [DMFNiLHNi(NO2)2NiLHDMF] (VIII), Green
NiLACDMF]. (Color figure online) [DMFNiLHNi(NO3)2NiLHDMF] (IX). (Color figure online)
100 100
50 50
0 0
0 100 200 300 400 500 600 0 100 200 300 400 500 600
Temperature/°C Temperature/°C
Fig. 11 DTA curves of complexes I–V. Black [DMFNiLCu(NO )  Fig. 13 DTA curves of complexes VI–IX. Black [DMFNiLH2 2
 H H HNiL DMF] (I), Red {[DMFNiLCu(NO3)2NiLDMF]DMF} (II), Cu(NO2)2NiL DMF] (VI), Red [DMFNiL Cu(NO3)2NiL DMF]
Blue [DMFNiL H HNi(NO2)2NiLDMF] (III), Green {[DMFNiL (VII), Blue [DMFNiL Ni(NO2)2NiL DMF] (VIII), Green
H H
Ni(NO ) NiLDMF]2DMF} (IV), Pink {[DMFNiLACCu(NO )  [DMFNiL Ni(NO3)2NiL DMF] (IX). (Color figure online)3 2 3 2
NiLACDMF]DMF}. (Color figure online)
KAS:
equations; isothermal calculations were done according to      b AEa Ea
Coats–Redfern (CR) equations from non-isothermal methods. In ¼ In 
T2 RgðaÞ RT
Equations used in these calculations are given as follows:
Ozawa: Coats–Redfern:
         
¼ AEa   Ea gðaÞ AR Ealog b log ð Þ 2:315 0:4567 In ¼ In Rg a RT T2 bEa RT
OFW:
where b is a heating speed as C min-1, R universal gas
    constant, Ea thermal disintegration activation energy, A
¼ 0:0048AEb a EaIn In  1:0516 Arrhenius pre-exponential factor, T temperature in K, g(a)
RgðaÞ RT fractional completed fraction of thermal fracture reaction.
123
endo DTA/µV exo Mass loss/%
endo DTA/µV exo Mass loss/%
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1331
These equations were generated considering reaction order
n = 1 and realized as mentioned above.
Asolid ! Bsolid þ Cgas
For Coats–Redfern equation, b = 10 C min-1 and
g(a) value were calculated between 0.1 and 0.9 and cal-
culations were made by graphic assistance. In application
of non-isothermal methods, b value changed in the range
of 5, 10, 15, 20, 25 C min-1 and graphical results were
obtained. On software of TG device, there is extra software
for Ozawa method; for that reason, Ozawa results were
calculated from software of device (TA Workstation,
TA60 kinetic analysis Program, version 2.01, Shimadzu
Corp.). But software gave error signal for nitrite and nitrate
ion explosions.
FOW and KAS methods were performed by manipu-
lation. But since temperature change showed anomaly for
explosion reactions of nitrite and nitrate ions, g(a) calcu-
lation was able to be done by taking the values between
0.05–0.18 and 0.85–0.95. Results calculated according to
four methods are given in Tables 6 and 7. As shown in
Fig. 10 and Table 3 for complexes prepared from Schiff
bases (I–IV), there are two thermal reactions: First reaction
is the separation of coordinative DMF molecules and
second reaction is the explosion reaction of nitrite and
nitrate. These values were calculated for both reactions.
From the above equation, Ea and A values could be cal-
culated. Thermodynamic parameters in thermal reaction
could be calculated by using these values.
 
¼ AhDS 2:303 log R
kT
DH ¼ Ea  RT
DG ¼ DH  TDS
Separation of coordinative DMF molecules reaction
only exists for I–IV-numbered complexes as it is shown in
Fig. 10 as well. The results found by the above equations
for the DMF thermal separation reaction are given in
Table 4. According to the method, Ea and A values were
calculated different for this DMF separation reaction. By
the way, three Arrhenius pre-exponential constant value
(A) is significantly different compared to others; A value
calculated with OFW method for complex I, A value cal-
culated with KAS method for complex II and A value
calculated with CR equation for complex IV are also found
significantly different; other values are in comparable sizes.
As shown in Table 4, Ozawa software gave no results
for complex II, IV and VII. Only two of results, complex I
and Complex VI (respectively, 123 and 113.35 kJ mol-1,
1.76.1011 min-1), obtained from Coast–Redfern equation
could be comparable with other results for Ea and A values.
Other values calculated by Coats–Redfern equation are
123
Table 3 Thermoanalytical data of the complex I–IX
Complexes First thermal reaction solvate Second thermal reaction coordinative Third thermal reaction mass
DMF mass loss endothermic DMF mass loss, endothermic loss of detonation, exothermic
Temperature Mass loss % Temperature Mass loss % Temperature Mass loss
range/C Exp./% found range Exp./% found range/C % found
[DMFNiLCu (NO2)2DMF]1/2DMF complex I 55–92/DTA peak:74 4.52/4.58 ± 0.08 176–211/DTA peak:199 14.37/9.07 ± 0.07 256–291/DTA peak:274 8.06 ± 0.83
[DMFNiLCu (NO3)2DMF]DMF complex II 66–112/DTA peak:90 6.73/10.30 ± 0.16 161–193/DTA peak:188 13.47/13.45 ± 0.17 325–342/DTA peak:333 21.38 ± 3.26
[DMFNiLNi (NO2)2DMF]complex III 180–206/DTA peak:200 14.98/14.04 ± 1.02 273–295/DTA peak:283 9.37 ± 1.03
{[DMFNiLNi(NO3)2NiLDMF]2DMF} complex IV 73–122/DTA peak:98 12./12.40 ± 0.28 168–202/DTA peak:185 12.97/12.81 ± 0.12 325–342/DTA peak:332 19.73 ± 2.78
{[DMFNiLACCu(NO3)2NiLACDMF]DMF} complex V 48–97/DTA peak:70.08 6.40/5.84 ± 0.95 125–179/DTA peak:145 12.81/10.97 ± 1.29 185–247/DTA peak:185 14.48 ± 0.91
[DMFNiLHCu(NO2)2NiLHDMF] complex VI 222–254/DTA peak:229 13.39 ± 1.89
[DMFNiLHCu(NO3)2NiLHDMF] complex VII 233–267/DTA peak:242 27.97 ± 0.79
[DMFNiLHNi(NO2)2NiLHDMF] complex VIII 222–269/DTA peak:264 34.23 ± 2.48
[DMFNiLHNi(NO3)2NiLHDMF] complex IX 267–288/DTA peak:279 30.70 ± 0.22
1332 N. Acar et al.
significantly higher; Ea and A values were calculated
higher, and as a result, other thermodynamic parameters
are calculated different. In explosion reaction of nitrate and
nitrite ions, Ozawa method and OFW methods gave quite
similar results. Only if Ea values are compared, OFW and
Ozawa obtained from KAS method is similar, but A value
calculated with KAS is as small as not comparable.
Values specified in Table 5 are the rates which were
calculated for explosion reaction of nitrite and nitrate ions
with an organic substance. Ozawa software did not give
any result for three complexes. These are complexes con-
taining nitrate. As it is known nitrate and nitrite ions are
oxidizing ions, they oxidize organic substance with organic
substance rapidly and cause rapid explosive reaction. First
explosive substance black powder contains nitrate salt,
coal dust and elemental dust sulfur in [45]. Nitrate includes
more oxygen atom, and for that reason, mass loss and
liberated energy in nitrated complexes are more in explo-
sion reaction and this situation is shown in Figs. 10, 11 and
Table 3. Gas product amount is expected to be excessive in
nitrate complex explosion reactions, since it is a rapid
reaction during the diffusion of these gas products, tem-
perature distribution around pan is contrary to expectation.
Temperature increases in a short time during explosion.
But gas product amount is high, and during the diffusion of
gas molecules around pan, temperature is decreased again
which is a result of heat transfer of these gas molecules.
This situation creates an anomaly in TG curve. Figure 14
shows TG curve of {[DMFNiLNi(NO3)2NiLDMF]
2DMF}, complex IV, and Fig. 15 shows DTA curve in
detail. Here, there can be seen three reactions, first reaction
is a mass loss belonging to DMF’s which exist as solvate
separation; it has been occured between 73 and 122 C.
Second thermal reaction belongs to coordinative DMF’s
loss and occured between 168 and 202 C. Third thermal
reaction is explosion reaction. This explosion reaction was
occured between 325 and 342 C. Mass loss at the
beginning of explosion reaction shows a negative slope as
expected. But as long as the reaction forwards, slope goes
through positive side because temperature does not
increase but decreases in contrary, because the gases
generated during the explosion and move away quickly and
this generated gases carry out the reaction heat from Pt
pan. For this reason, the temperature decreases during
explosion reaction. In DTA curve, extraordinary cycle is
observed instead a Gaussian-type signal. This situation is
clearly shown in Figs. 14 and 15. Two thermal reactions
were proceeded as expected. The mass loss increased with
temperature increases and expected TG curves were cal-
culated, but it is seen that mass loss and temperature
decreased in third thermal reaction. In parallel to this,
signals of first two thermal reactions are normal
endothermic signals in Fig. 15, but there is an anomaly in
123
Table 4 Thermokinetic results of complex I–IV for DMF removal reaction (first thermal reaction)
Complex Methods
Ozawa Coats–Redfern OFW KAS
Ea/kJ mol
-1 Arrhenius pre- E /kJ mol-1a )/R
2 Arrhenius pre- E /kJ mol-1)/R2 Arrhenius pre- E /kJ mol-1 2a a )/R Arrhenius pre-
exponential factor/ (regression value) exponential factor/ (regression value) exponential factor/ (regression value) exponential factor/
min-1 min-1 min-1 min-1
I 159.36 ± 4.12 1.40 9 1012 134.03 ± 3.49/0.9864 2.56 9 1014 258.89 ± 9.22/0.9495 3.43 9 1019 249.92 ± 8.84/0.9430 1.48 9 1018
II 106.53 ± 7.50 8.71 9 1010 167.79 ± 7.64/0.9182 2.11 9 1012 83.63 ± 0.30/0.9960 1.49 9 109 81.19 ± 0.29/0.9958 4.65
III 169.27 ± 14.10 2.72 9 1012 141.49 ± 8.05/0.8408 2.91 9 1015 117.28 ± 2.43/0.9493 2.81 9 1012 115.73 ± 2.34/0.9451 8.93 9 103
IV 113.51 ± 5.02 2.33 9 108 177.83 ± 3.80/0.9480 1.09 9 1020 83.12 ± 0.79/0.9723 2.36 9 109 75.16 ± 0.76/0.9642 1.31 9 109
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1333
25
20
15
10
5
0
0 100 200 300 400 500 600
Temperature/°C
Fig. 14 TG curve of the complex IV ({[DMFNiLNi(NO3)2NiL
DMF]2DMF})
350
250
200
150
100
50
0
–50
0 100 200 300 400 500 600
Temperature/°C
Fig. 15 DTA curve of the complex IV ({[DMFNiLNi(NO3)2NiL
DMF]2DMF})
third thermal reaction signal. In this situation, according to
Ozawa, OFW or KAS method, graphics drawn between
g(a)’s proper values (0.2–0.8), the lines deviate from lin-
earity. For that reason, Ozawa software is failed. In spite of
this in graphics which were drawn according to another
methods, g(a) values were calculated by taking relatively
closer to limit values.
Our general remarks were summarized in results given
in Tables 4 and 5
1. As mentioned before, coordinative DMF loss was
occurred as expected manner and observed as
endothermic reaction. Results which were found
according to four different methods for this thermal
reaction are comparable values to each other. There
are differences between the results calculated by these
methods, but this is a common situation for these semi-
experimental methods in the literature [32, 35]. Only
123
Table 5 Thermokinetic results of complex I–IV, VI–IX for explosion reaction of nitrite or nitrate ions (second thermal reaction)
Complexes Methods
Ozawa Coats–Redfern OFW KAS
E /kJ mol-1a Arrhenius pre- Ea/kJ mol
-1)/R2 Arrhenius pre- E /kJ mol-1 Arrhenius pre- E /kJ mol-1a a )/R
2 Arrhenius pre-
exponential factor/ (regression value) exponential factor/ exponential factor/ (regression value) exponential factor/
min-1 min-1 min-1 min-1
I 137.62 ± 12.99 5.92 9 1011 123.49 ± 3.45/0.9740 2.36 9 1011 135.95 ± 5.16/0.969 9.39 9 1013 128.82 ± 2.32/0.963 244.41
II Could not calc. 484.37 ± 23.78/0.9867 4.14 9 1041 158.52 ± 3.08/0.983 2.67 9 1011 165.22 ± 3.04/0.9814 4.28 9 105
III 131.56 ± 1.47 8.27 9 108 284.35 ± 13.64/0.9864 2.43 9 1026 142.78 ± 3.79/0.9379 7.97 9 1011 138.88 ± 4.79/0.9977 21.34
IV Could not calc. 232.83 ± 9.37/0.9881 1.38 9 1019 111.47 ± 1.13/0.9890 1.53 9 109 107.83 ± 1.09/0.9872 2.87
VI 129.59 ± 4.51 1.02 9 1015 113.35 ± 0.84/0.9390 1.76 9 1011 118.45 ± 1.87/0.9743 2.47 9 1014 115.56 ± 1.98/0.9690 6194.76
VII Could not calc. 515.44 ± 9.28/0.9776 1.76 9 1045 125.31 ± 1.97/0.9703 5.02 9 1010 122.88 ± 1.96/0.9656 1177.53
VIII 124.28 ± 8.18 1.84 9 109 369.54 ± 10.72/0.8948 1.38 9 1036 125.36 ± 1.12/0.9887 1.55 9 1011 116.29 ± 1.34/0.9867 338.32
IX Could not calc. 519.84 ± 11.44/0.9729 1.27 9 1050 131.47 ± 4.53/0.9389 5.50 9 1012 128.86 ± 4.09/0.9211 1125.17
endo DTA/µV exo Mass/mg
1334 N. Acar et al.
Table 6 Calculated thermodynamic parameters for DMF removal reaction (first thermal reaction)
Complex Methods
Ozawa Coats–Redfern OFW KAS
DH/ DS/ DG/ DH/ DS/ DG/ DH*/ DS/ DG/ DH/ DS/ DG/
kJ mol-1 J K-1 kJ mol-1 kJ mol-1 J K-1 kJ mol-1 kJ mol-1 J K-1 kJ mol-1 kJ mol-1 J K-1 kJ mol-1
I 155.26 -16.57 163.93 130.01 26.90 116.75 254.79 266.67 123.32 245.82 98.78 197.12
II 101.35 -41.60 127.67 163.44 99.04 101.74 78.45 -75.43 125.44 76.01 -238.29 224.46
III 169.92 -11.53 175.95 137.14 46.47 112.84 112.93 -11.26 118.82 113.38 -173.97 204.36
IV 109.16 -89.41 155.92 151.71 134.04 85.60 78.66 -70.16 115.35 111.00 -75.05 150.25
Table 7 Calculated thermodynamic parameters for explosion reactions of nitrite or nitrate ions (second thermal reaction)
Complex Methods
Ozawa Coats–Redfern OFW KAS
DH/ DS/ DG/ DH/ DH/ DS/ DG/ DH/ DH/ DS/ DG/ DH/
kJ mol-1 J K-1 kJ mol-1 kJ mol-1 kJ mol-1 J K-1 kJ mol-1 kJ mol-1 kJ mol-1 J K-1 kJ mol-1 kJ mol-1
I 137.62 -25.26 152.59 118.56 -32.90 138.07 131.89 18.47 122.86 114.75 -203.33 214.18
II 478.44 546.18 154.55 154.50 -30.17 169.07 161.20 -141.13 240.66
III 126.63 -79.92 173.42 279.42 254.54 128.47 138.66 -21.28 149.19 104.76 -223.71 215.49
IV 228.15 115.81 159.47 107.44 -73.11 142.82 103.81 -240.21 220.07
VI 124.91 37.13 104.00 108.67 -34.91 129.37 114.03 28.82 98.69 111.14 -177.16 205.39
VII 510.67 615.66 145.58 120.63 -44.17 145.49 118.19 -191.43 225.96
VIII 119.52 -72.98 161.33 364.77 441.31 103.07 120.58 -36.14 141.61 111.45 -202.08 229.06
IX 141.12 1.89 139.99 514.91 708.68 94.66 126.64 -6.54 130.78 123.61 -192.77 243.44
Arrhenius pre-exponential factor values that were calculated by thermokinetic methods is expected to be
calculated by KAS method are different from others. lower. Study was carried out in order to support this
Due to loss of DMF was observed on Schiff base suggestion. But due to explosion reactions did not give
complexes (complexes I–IV), it is not possible to expected TG curve, robust comparison results were not
compare these results with reduced Schiff base results. calculated. However, Ea values which were calculated with
2. Explosion reaction caused by nitrate and nitrite ions Ozawa, OFW and KAS method supports this suggestion.
was seen at all eight complexes too. As mentioned Average Ea values in Schiff base complex explosion
before, due to explosion is severe in complexes containing reactions were, respectively, according to Ozawa method
nitrate and TG curves showed anomaly, calculations were 134.59, OFW method 137.18 ± 19.57 kJ mol-1 and KAS
performed only at higher g(a) values. As shown in method 135.16 ± 23.84 kJ mol-1; however, these values
Table 5 according to Coats–Redfern equation, calculated in reduced Schiff base complexes were calculated, respec-
values are higher than others, Arrhenius pre-exponential tively, Ozawa method 126.94 kJ mol-1, OFW method
constant values are at unacceptable sizes. Ozawa and 125.15 ± 5.11 kJ mol-1 and KAS method 120.89 ±
OFW results are overlapped; in Ea, results obtained by 6.22 kJ mol
-1. Standard deviations are higher, and Ea
KAS method are comparable sizes with these values, but values which were calculated in reduced Schiff
Arrhenius pre-exponential constant values that were base complexes are lower as expected. But it is not
calculated by KAS are not acceptable again. Purpose of possible to calculate this on explosion reactions clearly
this study was to determine the strains of two different with these methods because TG curve shows anomaly.
species by comparison. Because while NiL has been able Tables 6 and 7 show the calculated thermodynamic
to synthesized and isolated, it was not possible to isolate parameters using the Ea and A values.
NiLH and still trinuclear complexes of both mononuclear
It was also considered that these complexes exhibit
complexes have been able to prepare. If NiLH had a
antimicrobial activity. To investigate the difference in
strain, this instability should have been in trinuclear
biological activities for two different complex types, we
complexes. In this situation, Ea value which was
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1335
Fig. 16 Biological activity of E. coli
the complexes prepared, C1, 1.5
complex I; C2, complex II; C3, 5 mg1
complex III; C4, complex IV; C5, 2.5 mg
0.5
complex VI; C6, complex VII 1.25 mg
and C8, complex IX 0
C1 C2 C3 C4 C5 C6 C8 0.625 mg
Compounds (C) 0.312 mg
P. aureginosa
1.5
5 mg
1
2.5 mg
0.5
0 1.25 mg
C1 C2 C3 C4 C5 C6 C8 0.625 mg
Compounds (C) 0.312 mg
S. aureus
1.5
5 mg
1
2.5 mg
0.5
1.25 mg
0
C1 C2 C3 C4 C5 C6 C8 0.625 mg
Compounds (C) 0.312 mg
E. feacalis
2
5 mg
1
2.5 mg
0
C1 C2 C3 C4 C5 C6 C8 1.25 mg
Compounds (C) 0.625 mg
1.5 5 mg
1
2.5 mg
0.5
1.25 mg
0
C1 C2 C3 C4 C5 C6 C8 0.625 mg
Compounds (C) 0.312 mg
performed antibacterial and antifungal activity experi- antifungal effects of both group of complexes. Thermoki-
ments. As mentioned above, inhibitory effects of these netic results show that there is a small difference between
complexes analyzed against two gram-negative bacteria two groups of complexes. But reaction that was examined
(E. coli and P. aureginosa), two gram-positive bacteria (S. with kinetic analysis is an explosion reaction. No doubt TG
aureus and E. feacalis) and one fungus (C. albicans). curve in explosion reactions was not good enough.
Results belonging to eight complexes against above-men- Therefore, not observing a big difference in biological
tioned microorganisms are given in Fig. 16. activity should be expected. If this study could be repeated
As shown in Fig. 16, there has been inhibitory effects with anions other than nitrate and nitrite anions, result
observed against bacterial species and a fungus yet there is would show clear comparison with respect to antimicrobial
no significant difference between antibacterial and activity.
123
 Biological activity 
 Biological activity    of compounds  Biological activity  Biological activity 
 Biological activity 
   of compounds (absent or present)    of compounds    of compounds 
   of compounds 
(absent or present) (absent or present) (absent or present) (absent or present)
1336 N. Acar et al.
Conclusion 14. Biswas S, Ghosh A. Use of Cu(II)-di-Schiff bases as metalloli-
gands in the formation of complexes with Cu(II), Ni(II) and
Zn(II) perchlorate. Polyhedron. 2013;65:322–31.
Totally eight trinuclear complexes were prepared from two 15. Arıcı C, Ülkü D, Atakol O. Bis{(N,N0-dimethylformamide) (l-
different groups where nitrate and nitrite ions exist as l- formato)[l-bis(salicylidene)-1,3-propanediaminato)] nickel(II)}-
bridge and thermokinetic parameters were determined by cobalt(II). Anal Sci. 2002;18:959–60.
four different methods isothermally and non-isothermally. 16. Ercan F, Ateş BM, Durmuş S, Atakol O. Structural analysis of
bis{(B,N’-dimethylformamide)(l-formato)[l-bis(salicylidene)-
Obtained data compared and stability among groups was 1,3-propanediaminato]nickel(II)}copper(II) and zinc(II) mono-
researched. Small difference was determined between hydrate hetero-trinuclear complexes. Cryst Res Tecnol.
activation energies, but this difference was not calculated 2004;39:470–6.
at biological activities. As a result, it was concluded that 17. Chen YN, Ge YY, Zhou W, Fang L, Gu ZG, Ma GM, Li WS. The
first Mn–Zn heterometallic dinuclear compound based on Schiff
trinuclear complexes in some cases are more stable than base ligand N,N0-bis(salicylidene)-1,3-propanediamine. Inorg
mononuclear units. Chem Commun. 2011;14:1228–32.
18. Akay A, Arıcı C, Atakol O, Fuess H, Svoboda I. Synthesis,
crystal structure and thermoanalysis of bis {[l-bis-N,N0(2-hy-
droxybenzoyl)-1,3-propandiaminato](N,N0-dimethylformamide)
(l-benzoato) nickel(II)} nickel(II). J Coord Chem. 2006;59:
References 933–8.
19. Atakol O, Tatar L, Akay MA, Ülkü D. Crystal structure of trin-
1. Fukuhara C, Tsuneyoshi K, Matsumoto N, Kida S, Mikuriya M, uclear complex, Bis[l-N,N0-bis(salicylidene)1,3-propanediami-
Mori M. Synthesis and characterization of trinuclear Schiff-base nato(dimethylformamide)(l-nitrito)nickel(II)]cobalt(II). Anal
complexes containing sulphur dioxide or hydrogensulphite ions Sci. 1999;15:101–2.
as bridging groups. J Chem Soc Dalton Trans. 1990. doi:10.1039/ 20. Atakol O, Arıcı C, Tahir MN, Kurtaran R, Ülkü D. Crystal
DT9900003473. structure of Bis[l-N,N0-bis(salicylidene)1,3-propanediami-
2. Gerli A, Hagen KS, Marzilli LG. Nuclearity and formulation of nato(dimethylformamide)(l-nitrato)nickel(II)]nickel(II). Dimethyl
SALPN2- complexes formed from M(O2CCH3)2. Inorg Chem. formamide solvate. Anal Sci. 1999;15:933–4.
1991;30:4673–6. 21. Yıldırım LT, Atakol O. Crystal structure analysis of Bis {(N,N0-
3. Ülkü D, Tahir MN, Atakol O, Nazir H. Bis{(l-acetato) dimethylformamide)-[l-bis-N,N0(2-oxybenzyl)-1,3-propanediami-
[l-bis(salicylidene)-1,3-propanediaminato)](N,N0-dimethylfor- nato](l-acetato) nickel(II)}nickel(II). Cryst Res Technol.
mamide)nickel(II)}cadmium(II). Acta Cryst. 1997;C53:872–4. 2002;37:1352–9.
4. Ülkü D, Ercan F, Atakol O, Dinçer FN. Bis{(l-acetato) 22. Reglinski J, Taylor MK, Kennedy AR. Hydrogenated Schiff base
[l-bis(salicylidene)-1,3-propanediaminato)](dimethylsulphoxide) ligands. Inorg Chem Commun. 2006;9:736–9.
nickel(II)}nickel(II). Acta Cryst. 1997;C53:1056–7. 23. Kurtaran R, Yıldırım LT, Azaz AD, Namlı H, Atakol O. Syn-
5. Uhlenbrock S, Wegner R, Krebs B. Syntheses and characteriza- thesis, characterization, crystal structure and biological activity of
tion of novel tri- and hexa-nuclear zinc complexes with biomi- a novel heterotetranuclear complex. J Inorg Biochem. 2005;
metic chelate ligands. J Chem Soc Dalton Trans. 1996. doi:10. 99:1937–44.
1039/DT9960003731. 24. Mustapha A, Busche C, Reglinski J, Kennedy AR. The use of
6. Atakol O, Nazir H, Aksu M, Arıcı C, Ercan F, Çiçek B. Some Di- hydrogenated Schiff base ligands in the synthesis of multi
and trinuclear zinc complexes: anion ınduced complex formation. metallic compounds II. Polyhedron. 2011;30:1530–7.
Synth React Inorg Met Org Chem. 2000;30:709–18. 25. Song Y, Gamez P, Roubeay O, Mutikainen I, Turpeinen U,
7. Ercan F, Atakol O. A linear trinuclear NiII–MnII–NiII complex Reedijk J. Structure and magnetism of two new linear trinuclear
with a l-acetato bridge. Acta Cryst. 1998;C54:1268–70. copper(II) clusters obtained from the tetradentate N2O2 ligand
8. Ercan F, Atakol O, Arıcı C, Svoboda I, Fuess H. Tgree bis(2-hydroxybenzyl)-1,3-diaminopropane. Inorg Chim Acta.
heteronuclear Schiff base complexes of nickel(II), with cobal- 2005;358:109–15.
t(II), copper(II) and manganese(II). Acta Cryst. 2002;C58: 26. Aksu M, Durmuş S, Sarı M, Emregül KC, Svoboda I, Fuess H,
m193–6. Atakol O. Investigation on the thermal decomposition some
9. Sanmartin J, Bermejo MR, Garia-Deibe AM, Maneiro M, Lage heterodiniclear NiII–MII complexes prepared from ONNO type
C, Costa-Filho AJ. Mono and polynuclear complexes of Fe(II), reduced Schiff Base compounds (MII=ZnII–CdII). J Therm Anal
Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with N,N0-bis(salicyli- Calorim. 2007;90:541–7.
dene)-1,3-dianino-2propanol. Polyhedron. 2000;19:185–92. 27. Öz S, Titiš J, Nazır H, Atakol O, Boca R, Svoboda I, Fuess H.
10. Shi DH, You ZL, Xu C, Zhang Q, Zhu HL. Synthesis, crystal Synthesis, structure and magnetic properties of Ni(II)–Co(II)
structure and urease inhibitory activities of Schiff base metal heterodinuclear complexes with ONNO type Schiff bases as
complexes. Inorg Chem Commun. 2007;10:404–6. ligands. Polyhedron. 2013;59:1–7.
11. Saha S, Sasmal A, Choudhury CR, Gomez-Garcia CJ, Garribba 28. Durmuş S, Ergun Ü, Jaud JC, Emregül KC, Fuess H, Atakol O.
E, Mitra S. A new linear double bridged trinuclear Cu(II) Schiff Thermal decomposition of some linear trinuclear Schiff base com-
base complex. Polyhedron. 2014;69:262–9. plexes with acetate bridges. J Therm Anal Calorim. 2006;86:337–46.
12. Das LK, Kadam RM, Bauza A, Frontera A. Differences in 29. Ozawa T. Kinetic analysis of derivative curves in thermal anal-
nuclearity shapes and coordination modes of azide in the com- ysis. J Therm Anal. 1970;2:301–24.
plexes of Cd(II) and Hg(II) with a metalloligand [CuL] (H2L= 30. Koga N. Ozawa’s kinetic method for analysing thermoanalytical
N,N0-bis(salicylidene)-1,3-propanediamine). Inorg Chem. 2012; curves. J Therm Anal Calorim. 2013;113:1527–41.
51:12407–18. 31. Ledeti I, Fuliaş A, Vlase G, Vlase T, Bercean V, Doca N.
13. Hazari H, Ghosh A. Trinuclear complexes of [CuL] (H2L=N,N
0- Thermal behaviour and kinetic study of some triazoles as
bis(salicylidene)-1,4-butanediamine with HgX2 (X=N -3 and potential anti-inflammatory agents. J Therm Anal Calorim.
NCO-). Polyhedron. 2015;87:403–10. 2013;114:1295–305.
123
The investigations of thermal behavior, kinetic analysis, and biological activity of trinuclear... 1337
32. Abdel-Kader NS, Amin RM, El-Ensary AL. Complexes of Schiff 39. Soliman AA, Linert W. Investigations on new transition matal
base of benzopyran-4-one derivative. J Therm Anal Calorim. chelates of 3-methoxy-salicylidene-2-aminothiophenol Schiff
2016;123:1695–706. base. Thermochim Acta. 1999;338:67–75.
33. Zziana A, Vecchio S, Gdaniee M, Czapik A, Hadzidimitriou A, 40. Oxford Diffraction CrysAlis CCD and CrysAlis RED. Version
Lalia-Kantouri M. Synthesis, thermal analysis, and spectroscopic 1.170.14. Oxfordshire: Oxford Diffraction; 2002.
and structural characterizations of zinc(II) complexes with sali- 41. Sheldrick GM. SHELXS_97 and SHEXL_97, program for crystal
cylaldehydes. J Therm Anal Calorim. 2013;112:455–64. structure solution and refinement. Göttingen: University of
34. Kullyakool S, Danvirutai C, Siriwong K, Noisong P. Determi- Göttingen; 1997.
nation of kinetic triplet of the synthesized Ni3(PO4)2.8H2O by 42. Farrugia LJ. WinGX suite for small-molecule single-crystal
non-isothermal and isothermal kinetic methods. J Therm Anal crystallography. J Appl Cryst. 1999;32:837–8.
Calorim. 2015;115:1497–507. 43. Atakol O, Nazir H, Arıcı C, Durmuş S, Svoboda I, Fuess H. Some
35. Koyundereli-Çılgı G, Çetişli H, Donat R. Thermal kinetic anal- new Ni–Zn heterodinuclear complexes: square-pyramidal nick-
ysis of uranium salts. J Therm Anal Calorim. 2014;115:2007–20. el(II) coordination. Inorg Chim Acta. 2003;342:295–300.
36. Krajnikova A, Rotaru A, Györyova K, Homzova K, Manolea HO, 44. Öz S, Arıcı C, Emregül KC, Ergun Ü, Atakol O, Kenar A.
Kovarova J, Hudecova D. Thermal behaviour and antimicrobial Heteronuclear Ni(II)–Sn(II) complexes from reduced ONNO type
assay of some new zinc(II) 2-aminobenzoate complex compound Schiff base compounds. Z Kristallogr. 2007;222:249–54.
with bioactive ligands. J Therm Anal Calorim. 2015;120:73–83. 45. Klapötke TM. Chemistry of high-energy materials. Berlin: Walter
37. Sarada K, Muraleedharam K. Effect of addition of silver on the de Gruyter; 2011. p. 38.
thermal decomposition kineticsw of copper oxalate. J Therm
Anal Calorim. 2016;123:643–51.
38. Ebrahimi HP, Hadi JS, Abdulnabi ZA, Bolandnazar Z. Spectro-
scopic, thermal analysis and DFT computational studies of Salen
type Schiff base complexes. Spectrochim Acta A. 2014;117:
485–92.
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