Artigo_Zn_2

Prévia do material em texto

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/257616165
Synthesis, thermal analysis, and spectroscopic and structural
characterizations of zinc(II) complexes with salicylaldehydes
Article  in  Journal of Thermal Analysis and Calorimetry · April 2012
DOI: 10.1007/s10973-012-2719-2
CITATIONS
23
READS
148
6 authors, including:
Some of the authors of this publication are also working on these related projects:
Complex Co(II) View project
competition between vaporization and decomposition in ionic liquids View project
Stefano Vecchio
Sapienza University of Rome
118 PUBLICATIONS   1,261 CITATIONS   
SEE PROFILE
Maria Gdaniec
Adam Mickiewicz University
267 PUBLICATIONS   2,378 CITATIONS   
SEE PROFILE
Agnieszka Czapik
Adam Mickiewicz University
47 PUBLICATIONS   216 CITATIONS   
SEE PROFILE
Maria Lalia-Kantouri
Aristotle University of Thessaloniki
93 PUBLICATIONS   750 CITATIONS   
SEE PROFILE
All content following this page was uploaded by Stefano Vecchio on 15 October 2014.
The user has requested enhancement of the downloaded file.
https://www.researchgate.net/publication/257616165_Synthesis_thermal_analysis_and_spectroscopic_and_structural_characterizations_of_zincII_complexes_with_salicylaldehydes?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_2&_esc=publicationCoverPdf
https://www.researchgate.net/publication/257616165_Synthesis_thermal_analysis_and_spectroscopic_and_structural_characterizations_of_zincII_complexes_with_salicylaldehydes?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_3&_esc=publicationCoverPdf
https://www.researchgate.net/project/Complex-CoII?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_9&_esc=publicationCoverPdf
https://www.researchgate.net/project/competition-between-vaporization-and-decomposition-in-ionic-liquids?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_9&_esc=publicationCoverPdf
https://www.researchgate.net/?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_1&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Stefano_Vecchio?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_4&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Stefano_Vecchio?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_5&_esc=publicationCoverPdf
https://www.researchgate.net/institution/Sapienza_University_of_Rome?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_6&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Stefano_Vecchio?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_7&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Gdaniec?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_4&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Gdaniec?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_5&_esc=publicationCoverPdf
https://www.researchgate.net/institution/Adam_Mickiewicz_University?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_6&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Gdaniec?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_7&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Agnieszka_Czapik?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_4&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Agnieszka_Czapik?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_5&_esc=publicationCoverPdf
https://www.researchgate.net/institution/Adam_Mickiewicz_University?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_6&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Agnieszka_Czapik?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_7&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Lalia-Kantouri?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_4&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Lalia-Kantouri?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_5&_esc=publicationCoverPdf
https://www.researchgate.net/institution/Aristotle_University_of_Thessaloniki?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_6&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Maria_Lalia-Kantouri?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_7&_esc=publicationCoverPdf
https://www.researchgate.net/profile/Stefano_Vecchio?enrichId=rgreq-0cad45e808661fbc9bef761c9bb04b40-XXX&enrichSource=Y292ZXJQYWdlOzI1NzYxNjE2NTtBUzoxNTI0NTc0NjQyNTg1NjFAMTQxMzM2MDEwMDA1Nw%3D%3D&el=1_x_10&_esc=publicationCoverPdf
Synthesis, thermal analysis, and spectroscopic and structural
characterizations of zinc(II) complexes with salicylaldehydes
Ariadni Zianna • Stefano Vecchio • Maria Gdaniec •
Agnieszka Czapik • Antonis Hatzidimitriou •
Maria Lalia-Kantouri
Italian Special Issue
! Akadémiai Kiadó, Budapest, Hungary 2012
Abstract In this study, three new zinc(II) complexes with
5-substituted salicylaldehyde ligands (X-saloH) (X =
5-chloro, 5-nitro and 5-methyl) with the general formula
[Zn(X-salo)2(CH3OH)n], (n = 0 or 2) were synthesized.
An octahedral geometry was found for both the complexes
[Zn(5-NO2-salo)2(CH3OH)2] and [Zn(5-Cl-salo)2(CH3OH)2]
by single-crystal X-ray diffraction analysis. These complexes
were characterized also by spectroscopy (IR and 1H-NMR).
Simultaneous TG/DTG–DTA techniques were used to ana-
lyze their thermal behavior under inert atmosphere, with
particular attention to determine their thermal degradation
pathways, which was found to be a multi-step decomposition
accompanied by the release of the ligand molecules. Finally,
the kinetic analysis of the decomposition processes was per-
formed by applying both the isoconversional Ozawa–Flynn–
Wall (OFW) and the Kissinger–Akahira–Sunose (KAS)
methods.
Keywords Crystal structure ! TG/DTG–DTA ! Zinc(II)
complexes ! Salicylaldehydes ! Ozawa–Flynn–Wall
method ! Kissinger–Akahira–Sunose method
Introduction
Zinc ion is an essential trace element for growth and devel-
opment in all forms of life, as it has been proposed to have
beneficialtherapeutic and preventive effects on infectious
diseases and it tends to be tightly boundwithinmore than 300
metalloenzymes [1]. On the other hand, the strong coordi-
nating properties of 2-hydroxy-benzaldehydes (salicylalde-
hyde, saloH) and their derivatives with 3d transition metals
have stimulated research on these compounds, which find
applications in both pure [2] and applied chemistry fields,
such as in extractive metallurgy as analytic reagents [3].
These ligands are known to coordinate in a bidentate manner
with transition metals in the mono-anionic form, adopting
variant geometries from square-planar [4] to square pyra-
midal [5] and octahedral [6]. It has recently been found,
however, by us that under proper conditions, 3-OCH3-sali-
cylaldehyde with Fe(III) ion can coordinate with two dif-
ferent modes, and as bridging ligand, forming polynuclear
complexes [Fe2(3-OCH3-salo)8Na5]3OH!8H2O [7], while
2-OH-benzophenones give the simple complexes [Fe(2-OH-
benzophenone)3] [8]. Recently, there has been an increased
interest in the thermal behaviors of Zn complexes with
oxygen donor ligands like 4-bromobenzoato and 2-chloro-
benzoato complexes with bioactive ligands [9, 10] or
5-chlorosalicylate and acetylsalicylate [11, 12], and in this
respect, we prepared analogous compounds.
The aim of this study was to synthesize new Zn com-
plexes with salicylaldehydes and to characterize their
molecular structure by different techniques. Hence, three
new zinc(II) complexes formulated as [Zn(5-Cl-salo)2
(CH3OH)2] (1), [Zn(5-NO2-salo)2(CH3OH)2] (2), and
[Zn(5-CH3-salo)2 (3), where salo = anion of the salicyl-
aldehyde, were prepared and characterized by spectro-
scopic methods (IR and 1H-NMR). The crystal structure of
A. Zianna ! A. Hatzidimitriou ! M. Lalia-Kantouri (&)
Laboratory of Inorganic Chemistry, Department of Chemistry,
Aristotle University of Thessaloniki, 54 124 Thessaloniki,
Greece
e-mail: lalia@chem.auth.gr
S. Vecchio
Dipartimento S.B.A.I., Sapienza, Università di Roma,
Via del Castro Laurenziano 7, 00161 Rome, Italy
M. Gdaniec ! A. Czapik
Faculty of Chemistry, Adam Mickiewicz University,
60780 Poznan, Poland
123
J Therm Anal Calorim (2013) 112:455–464
DOI 10.1007/s10973-012-2719-2
both the complexes, [Zn(5-Cl-salo)2(CH3OH)2] and [Zn(5-
NO2-salo)2(CH3OH)2], verified by the single-crystal X-ray
diffraction analysis, is reported in this study. Moreover, the
thermal behaviors of these new complexes were investi-
gated by the simultaneous TG/DTG–DTA technique in
nitrogen atmosphere in the temperature range from room
temperature (R.T.) to 600 "C, and kinetic analysis of their
thermal decomposition processes was carried out.
In order to confirm the stability scale provided on the
basis of the onset decomposition temperature, we decided
to follow the same approach used in some articles recently
published [13, 14]: a kinetic analysis of the thermal
decomposition stages using multi-heating kinetic methods
is recommended for kinetic computations by the ICTAC
Kinetic Committee [15], in particular the isoconversional
methods of Ozawa–Flynn–Wall (OFW) [16, 17] and Kis-
singer–Akahira–Sunose (KAS) [18].
Experimental
Materials and synthesis of the complexes
[Zn(X-salo)2(CH3OH)n]
The ligands, 2-hydroxy-5-chlorobenzaldehyde (5-Cl-sali-
cylaldehyde, 5-Cl-saloH), 2-hydroxy-5-nitrobenzaldehyde
(5-NO2-salicylaldehyde, 5-NO2-saloH), and 2-hydroxy-5-
methylbenzaldehyde (5-CH3-salicylaldehyde, 5-CH3-sa-
loH), and the metal salt Zn(NO3)2!6H2O were obtained as
reagent grade from Aldrich and used as received. Sol-
vents for preparation and physical measurements of ‘‘extra
pure’’ grade were obtained from Fluka without further
purification.
The title complexes were prepared by adding dropwise
a methanolic solution of 1 mmol substituted salicylalde-
hyde and 1 mmol CH3ONa to a methanolic solution of
Zn(NO3)2!6H2O (0.5 mmol) at R.T. The solution was stirred
for 2 h, which then turned yellowish. The solid was formed
after several days, and then it was filtered, washed with
water, and dried in vacuo. Conductivities inDMSO solutions
were found to have values between 5.0 and 15.7 lS cm-1,
denoting the neutral character of the compounds.
1. [Zn(5-Cl-salo)2(CH3OH)2]: yellow microcrystalline
solid, yield 65.0 %. Stoichiometry calculated for C16H16
ZnCl2O6: C 43.62, H 3.66, Zn 14.84; Found: C 43.58,
H 3.62, Zn 14.65; infrared (IR) spectrum (KBr): selected
peaks in cm-1: 3,432 m(O–H) of coordinated methanol,
1638 s m(C=O), 1316 s m(C–O ? Zn), 780 m m(C–Cl),
513 m (Zn–O); 1H-NMR spectrum (DMSO), peaks (d) in
ppm: 9.73 s (H–C=O), 8.19, 7.32, 6.73 (Ph).
2. [Zn(5-NO2-salo)2(CH3OH)2]: yellow solid, yield
63.0 %. C16H16 ZnN2O10: C 41.62, H 3.49, N 6.07, Zn
14.16; Found: C 41.15, H 3.54, N 5.93, Zn 13.86; IR
spectrum (KBr): selected peaks in cm-1: 3,507 m(O–H) of
coordinated methanol, 1647 and 1602 s m(C=O), 1330 s
m(C–O ? Zn), 1547 and 1330 s m(C–NO2), 504 m (Zn–O);
1H-NMR spectrum (DMSO), peaks (d) in ppm: 9.77
(H–C=O), and 8.38, 7.97, 6.46 (Ph).
3. [Zn(5-CH3-salo)2]: yellow solid, yield 57.0 %.
C16H14ZnO4: C 57.25, H 4.20, Zn 19.48; Found: C 56.05,
H 4.03, Zn 19.24; IR spectrum (KBr): selected peaks in
cm-1: 2854, 1460 s and 1396 m m(C–H) of the CH3, 1645
and 1589 s m(C=O), 1315 s v(C–O ? Zn), 539 m (Zn–O);
1H-NMR spectrum (DMSO), peaks (d) in ppm: 9.75
(H–C=O), and 8.38, 7.97, 6.46 (Ph) and 3.3 s (CH3).
Instruments and methods
Microanalyses were carried out using a Perkin-Elmer 240
B CHN microanalyzer and Perkin-Elmer 5100 PC Atomic
Absorption Spectrophotometer for evaluating the metal
content. Infrared spectra in the region of 4,000–400 cm-1
were obtained in KBr disks with a Nicolet FT-IR 6700
spectrophotometer. Molar conductivities were measured in
DMSO solutions, employing a WTW conductivity bridge
and a calibrated dip type cell. 1H-NMR spectra in DMSO
solutions were recorded on a Bruker 300 MHz apparatus.
The simultaneous TG/DTG–DTA curves were obtained on
a SETARAM thermal analyzer, model SETSYS TG-DTA
1200. Samples (10.0 ± 0.2 mg) were placed in platinum
crucibles, and as reference was used an empty platinum
crucible. The compounds were heated from ambient tem-
perature to 600 "C under a flow rate of 80 ml min-1 of N2,
with several heating rates (5, 10, 15, and 20 "C min-1).
X-ray crystal structure determination
Single crystals of (1) [Zn(5-Cl-salo)2(CH3OH)2] were
obtained from the reaction mixture after slow evaporation.
Diffraction data were collected at 130 K with an Oxford
Diffraction Xcalibur E single-crystal diffractometer
equipped with an Oxford Cryostream device. Data col-
lection and reduction were performed with CrysAlis PRO
[19]. The structure was solved by direct methods with the
SHELXS–97 program [20] and refined by full-matrix
least-squares method on F2 with SHELXL-97 [20].
C-bound hydrogen atoms were generated geometrically in
idealized positions, and their displacement parameters
were set equal to 1.5Ueq(C) for the methyl groups, and
1.2Ueq(C) for the remaining H atoms. Hydrogen atom
from the O–H group was located in a different Fourier
map and freely refined.
Single crystals of (2) [Zn(5-NO2-salo)2(CH3OH)2] were
obtained from the reaction mixture after slow evaporation.
For the structural determination, a single crystal of the
compound was mounted on a Bruker Kappa APEX II
456 A. Zianna et al.
123
diffractometer. A total of 1,080 frames were collected. The
total exposure time was 1.50 h. The integration of the data
using a triclinic unit cell yielded a total of 3,960 reflections
to a maximum h angle of 25.09" (0.84 Å resolution), of
which 1,608 were independent [average redundancy 2.463
and 1,567 (97.45 %) were greater than 2r(F2)]. The final
cell constants were based on the refinement of the XYZ-
centroids of 3193 reflections above 20 r(I) with
5.633"\ 2h\ 50.10". The ratio of minimum to maximum
apparent transmission was 0.773. The structure was solved
using SUPERFLIP package and refined by full-matrixleast-squares method on F2 using the CRYSTALS package
version 14.00 [21]. All the non-hydrogen atoms have been
refined anisotropically. All the hydrogen atoms were found
at expected positions and refined using soft constraints. By
the end of the refinement, they were positioned using riding
constraints. The crystal data and some details of the data
collection and structure refinement for both compounds are
given in Table 1.
Theory for kinetic analysis
Solid-state kinetics is usually described by the explicit
dependence of the reaction rate by both the absolute
temperature and the extent of conversion a, according to
the following general equation:
da
dt
¼ kðTÞ ! f ðaÞ ð1Þ
where da/dt is the reaction rate, and k(T) is the rate
constant, temperature dependence (commonly assumed to
have the form of the Arrhenius equation) of which enables
us to re-write Eq. (1) in the following form:
da
dt
¼ A ! exp %E
RT
! "
! f ðaÞ ð2Þ
where A is the pre-exponential factor, E is the activation
energy, and f(a) is the differential model function.
Thermal analysis instruments under non-isothermal
conditions are commonly used to monitor decomposi-
tion of a solid substance by heating a powdered sample
of the tested compound under constant rate b. As a
result, with b = dT/dt, Eq. (2) can be written byelicit-
ing the temperature dependence of the reaction rate as
follows:
da
dt
¼ dT
dt
! da
dT
¼ b ! da
dT
¼ A ! exp%E
RT
! f ðaÞ ð3Þ
By rearranging Eq. (3) as
Table 1 Crystal data and structure refinement details for [Zn(5-Cl-salo)2(CH3OH)2] and [Zn(5-NO2-salo)2(CH3OH)2]
Empirical formula [Zn(C8H8ClO3)2] [Zn(C8H8NO5)2]
Formula weight 440.56 461.69
Crystal system Triclinic Triclinic
Temperature 120 K 295 K
Radiation Mo Ka Mo Ka
Space group P-1 P-1
Unit cell dimensions a = 5.0497(5) Å a = 5.1301(4) Å
b = 8.3861(10) Å b = 7.4131(6) Å
c = 11.1481(10) Å c = 12.3330(9) Å
a = 111.193(10)" a = 94.550(5)"
b = 96.253(8)" b = 95.650(6)"
c = 91.438(9)" c = 101.339(6)"
Volume 436.48(8) Å3 455.29(6) Å3
Z, Z0 1, 0.5 1, 0.5
Absorption coefficient (l) 1.742 1.410 mm-1
Reflections collected 3,630 3,945
Independent reflections 1,518 1,607
Completeness up to theta (max) 99.4 % 99.3 %
Data/restraints/parameters 1,518/0/120 1,559/0/133
Goodness-of-fit on F2 1.078 0.996
Final R indices [I[ 2r(I)] R1 = 0.0385, wR1 = 0.0969 R1 = 0.0213, wR1 = 0.0580
R indices (all data) R2 = 0.0420, wR2 = 0.1004 R2 = 0.0220, wR2 = 0.0589
Largest diff. peak and hole 0.56, -0.76 0.24 eÅ-3 - 0.24 Å-3
Characterizations of zinc(II) complexes with salicylaldehydes 457
123
da
f ðaÞ ¼
A
b
! exp %E
RT
! "
dt; ð4Þ
the integrals of both the left- and right-hand sides of Eq. (4)
yields
Zq
0
da
f ðaÞ
¼ gðaÞ ¼ A
b
ZT
0
exp
%E
RT
! "
dt ð5Þ
Unfortunately, Eq. (5) does not have exact analytic but
approximate solutions [15]. Nevertheless, the development
of modern computer software enabled us to overcome this
problem by means of numerical integration of the right-
hand side of Eq. (5) [15], providing us with very accurate
solutions.
One of the main aims of kinetic study regarding a
thermally activated process is to determine the so-called
kinetic triplet. A and E values representing the frequency of
vibrations and the energy barrier of the activated complex,
and differential or integral model function [f(a) or g(a),
respectively], which represent the reaction mechanism.
This goal is a very difficult task for processes, like thermal
decompositions, which have often a complex multi-step
nature, more easily describable in terms of several kinetic
triplets (one per each step).
Among the multi-heating kinetic methods that ICTAC
Kinetics Committee recommended for kinetic computa-
tions [15], isoconversional ones seem to provide more
reliable results. These methods are based on the assumption
that at constant extent of conversion reaction rate depends
only on temperature [f(a) or g(a) is constant].
In this non-isothermal study, two isoconversional
(integral) methods were considered, which are based on
two different approximations of the temperature integral of
Eq. (5), providing, for each fixed extent of conversion, a
linear equation of general form:
ln
b
TB
a
! "
¼ Const% C
Ea
R
! "
! 1
Ta;b
ð6Þ
where B and C are adjustable parameters, values of which
depend on the approximation made. For the former method
considered, the OFW method [16, 17], based on the
Doyle’s approximation [22], the following values are
replaced in Eq. (6): B = 0 and C = 1.052. For the latter
one, to get more accurate results, the KAS method [18] was
applied, by considering Eq. (6) in which B = 2 and C = 1.
The value of activation energy at each given extent of
conversion is calculated from the slope of the regression
line obtained by plotting the left-hand side of Eq. (6)
against the reciprocal temperature Ta,b
-1.
Pre-exponential factor and model function can be
accurately determined only in the case of processes that
follow approximately a single-step kinetics [15], for which
it can be expected that activation energy does not vary
appreciably over the entire range of the extent of conver-
sion a.
Results and discussion
General considerations and spectroscopic
characterization
The reaction of the Zn(NO3)2!6H2O with three substituted
salicylaldehydes (X-saloH) in methanol afforded solid
compounds in good yield. The characterization of their
molecular structure was made by elemental analyses and
conductivity measurements, as well as by spectroscopy (IR,
1H-NMR). The obtained zinc(II) compounds are neutral
and possess 1:2 metal-to-ligand composition, as it is indi-
cated from elemental analyses and the absence of electrical
conductivities in DMSO solutions. The complexes are
formulated as [Zn(5-Cl-salo)2(CH3OH)2], [Zn(5-NO2-sal-
o)2(CH3OH)2] and [Zn(5-CH3-salo)2], evidence also arisen
from the interpretation of the IR and 1H-NMR data of the
salicylaldehyde ligands and the complexes. In these com-
pounds, the salicylaldehydes behave as bidentate mono-
anionic ligands, through the carbonyl and the phenolic
oxygen atom [23, 24]. This knowledge provides a useful
basis, for predicting the structure of the yet unknown
analogous complexes. An IR spectrum is given for the
complex [Zn(5-NO2-salo)2(CH3OH)2] in Fig. 1, where it is
obvious that the evident peak at 3,507 cm-1 is clearly
attributable to the stretching vibration of the (O–H)
because of the coordinated molecules of methanol, while
selected IR peaks for all the compounds are given in
Table 2.
The 1H-NMR spectra of the title complexes give the
protons, attributable to the carbonyl group at about
9.80 ppm and the protons due to the benzene ring at the
area 8.4–6.5 ppm. The deprotonation of the phenolic
hydrogen can be easily seen from the absence of the –OH
signal, which is obvious to the 1H-NMR spectrum of the
ligand, appearing as broad peak at *12 ppm. Represen-
tative 1H-NMR spectra are given in Fig. 2 for the ligand
5-NO2-salicylaldehydeH (Fig. 2a) and for its complex
(Fig. 2b). Similar results have been referred for the Schiff
base ligand 2-hydroxy-3-methoxybenzaldehyde semicar-
bazone and its zinc complex [25].
Crystal structure of [Zn(5-Cl-salo)2(CH3OH)2]
The molecular structure of [Zn(5-Cl-salo)2(CH3OH)2] with
the atom numbering scheme is shown in Fig. 3. In the
crystal, the molecule exhibits crystallographic Ci symmetry
with the Zn(II) atom located on an inversion center. The
458 A. Zianna et al.
123
crystal structure clearly indicates that the Zn(II) atom is
chelated by two trans-positioned 5-chloro-salo ligands via
the phenolate and carbonyl oxygen atoms that occupy an
equatorial plane. A slightly distorted octahedral coordina-
tion geometry of Zn(II) is completed by two methanol
molecules in axial positions. The geometry of the metal
center (Table 3) is similar to those of the earlier reported
zinc(II) complexes with substituted salicylaldehyde ligands
[26, 27]. The six-membered chelate ring is ina sofa con-
formation resulting in a dihedral angle of 23.4" between the
equatorial plane and the plane of the 5-Cl-salo ligand. The
complex molecules are connected via O–H!!!O hydrogen
bonds between the methanol hydroxy group and the phe-
nolate O atom into one-dimensional polymeric structures
extending along the a axes.
Crystal structure of [Zn(5-NO2-salo)2(CH3OH)2]
The molecular structure of [Zn(5-NO2-salo)2(CH3OH)2],
shown with the atom numbering scheme in Fig. 4, clearly
indicates that the Zn(II) atom is chelated by two 5-nitro-salo
ligands via the phenolate and carbonyl oxygen atoms, while
two molecules of methanol are coordinated in trans posi-
tions, resulting in a distorted octahedral coordination
geometry. The Zn ion is again situated at the inversion
center. The geometry around the metal ion can be described
as an axially elongated octahedron as the four coordinated
oxygen atoms coming from the 5-nitro-salo ligand as bonded
to the zinc atom with nearly equal distances forming the
equatorial coordination plane, while the two oxygen atoms
coming from the coordinated methanol molecules lie at
longer distance from the metal ion (Table 4).
Thermal decomposition
TG/DTG–DTA in nitrogen
The TG/DTG–DTA curves of the complexes [Zn(5-Cl-
salo)2(CH3OH)2], [Zn(5-NO2-salo)2(CH3OH)2], and [Zn(5-
CH3-salo)2] at 5 "C min-1 under nitrogen atmosphere are
4000 3500 3000 2500 2000 1500 1000 500
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
35
06
.8
9
16
47
.3
3
16
02
.4
7
15
47
.8
5
13
30
.6
0
11
01
.2
3
93
8.
26 50
4.
49
Wavenumbers/cm–1
%
T
Fig. 1 IR spectrum of the compound [Zn(5-NO2-salo)2(CH3OH)2]
Table 2 Vibrational frequencies (m/cm-1) for selected absorption bands in the IR spectra of Zn compounds
Compound m (O–H) m (C–X)* m (C=O) m (C–O ? Zn) m (Zn–O)
[Zn(5-Cl-salo)2(CH3OH)2] 3,432 780 1,638 1,316 513
[Zn(5-NO2-salo)2(CH3OH)2] 3,507 1547, 1330 1647, 1602 1,330 504
[Zn(5-CH3-salo)2] 2845, 1460, 1396 1645, 1589 1,315 539
* X = Cl, NO2 or CH3
12 11 10 9 8 7 6 5 4 10 9 8 7 6 5 4
δ /p.p.m δ /p.p.m
a bFig. 2 1H-NMR spectra in
DMSO of: a the ligand
5-NO2-salicylaldehydeH and
b its complex [Zn(5-NO2-
salo)2(CH3OH)2]
Characterizations of zinc(II) complexes with salicylaldehydes 459
123
given in Figs. 5, 6, 7, respectively The decomposition
patterns of [Zn(5-Cl-salo)2(CH3OH)2] and [Zn(5-NO2-
salo)2(CH3OH)2] (as revealed by the shapes of the TG/
DTG–DTA curves) are quite similar, while some signifi-
cant differences are visible for the [Zn(5-CH3-salo)2].
Based on the mass loss and derivative mass loss plots (TG/
DTG), we can conclude that, under nitrogen, in the first
stage (ambient—100 "C), the compound [Zn(5-Cl-salo)2
(CH3OH)2] (Fig. 5) shows sudden mass loss (DTG peak
at 98 "C) of 9.0 %, with expected release of 2 mol of
coordinated methanol, compared with a theoretical mass
loss of 14.5 %, however. The DTA curve shows one sharp
endothermic peak at 98 "C, which is attributed to melting
followed by decomposition. The melting points of the
studied compounds were also determined by automated
melting point capillary tube system in static air, confirming
the melting points found on the DTA curves.
In the IR spectrum of the solid intermediate at 200 "C,
the peak at 3,432 cm-1, due to the stretching vibration of
the bond O–H of the coordinated methanol, is apparent
with much lower intensity compared with the IR spectrum
of the starting compound at R.T., while the profile of the
rest peaks is the same.
Upon increasing the temperature, the intermediate
undergoes further decomposition with sudden mass loss
during the second and third stages as follows: second stage
(100–300 "C, DTG peak at 276 "C, DTA exothermic peak
at 288 "C, and mass loss of 15.5 %), and third stage
(300–460 "C, DTG peak at 425 "C, DTA exothermic peak
at 427 "C, and mass loss of 20.0 %). The second stage is
attributed to the release of {H2CO ? Cl}, with calculated
value of 14.87 %, while the third one to one PhO group
with calculated value 20.88 %. The fourth stage
(460–600 "C) gives gradually mass loss of 3.5 % which
cannot be attributed to any particular species, because of
uncompleted pyrolysis at 600 "C.
The thermal decomposition of the compound [Zn(5-
NO2-salo)2(CH3OH)2] (Fig. 6) shows in the first stage
(ambient–130 "C) sudden mass loss (DTG peak at 130 "C)
of 15.0 %, with expected release of 2 mol of coordinated
methanol with a theoretical mass loss of 13.8 %. The DTA
curve shows one sharp endothermic peak at 130 "C, which
is attributed to melting followed by decomposition.
In the IR spectrum of the solid intermediate at 170 "C, the
peak at 3,507 cm-1, due to the stretching vibration of the
bond O–H of the coordinated methanol, is absent, while
the profiles of the rest peaks remain the same, confirming the
elimination of the methanol from the starting compound.
Upon increasing the temperature, the intermediates
undergo further decomposition with sudden mass loss
during the second and third stages as follows: second stage
(130–320 "C, DTG peak at 317 "C, DTA peak exothermic
at 319 "C, and mass loss of 11.0 %) and third stage
(320–380 "C, DTG peak at 350 "C, DTA peak exothermic
at 349 "C, and mass loss of 15.5 %). The second stage
coincides with the release of a NO2 group with calculated
value of 9.9 %, while the third one to the elimination of the
species {H2CO ? NO2}, with calculated value of 16.40 %.
The fourth stage (380–600 "C) gives gradually a mass loss
of 9.5 % which cannot be attributed to any particular
species, because of uncompleted pyrolysis at 600 "C.
The thermal decomposition profile of the compound
[Zn(5-CH3-salo)2] (Fig. 7) is quite different from those of
Cl1
C4 C3
C2
C5
C6 C1
C7
C8
O1
O2
O3
Zn1
Fig. 3 Molecular structure of [Zn(5-Cl-salo)2(CH3OH)2] with the
displacement ellipsoids shown at the 50 % probability level. Only
asymmetric part of the molecule is labeled
Table 3 Selected bond lengths and angles for [Zn(5-Cl-salo)2
(CH3OH)2]
Bond lengths/Å Bond angles/"
Zn(1)–O(1) 2.0105(17) O(1)–Zn(1)–O1i 180.00
Zn(1)–O(2) 2.093(2) O(1)–Zn(1)–O2 88.70(8)
Zn(1)–O(3) 2.140(2) O(1)–Zn(1)–O2i 91.30(8)
O(2)–Zn(1)–O2i 180.00
O(1)–Zn(1)–O3 89.21(8)
O(1)–Zn(1)–O3i 90.79(8)
O(2)–Zn(1)–O3 85.80(8)
O(2)–Zn(1)–O3i 94.20(8)
O(3)–Zn(1)–O3 180.00
Symmetry code: (i) 1 - x, 1 - y, -z
O3a
O4a
C4a
C3aC2a
C5a C6a
C1a
O1a
O102
O2
O1
O5
C8
C1
C7
C6 C5
C2 C3
C4
O5a
C8a
C7a
N101
Zn1
O4
O3
N1
Fig. 4 Molecular structure of [Zn(5-NO2-salo)2(CH3OH)2] with the
displacement ellipsoids shown at the 50 % probability level
460 A. Zianna et al.
123
the other two complexes, showing only two decomposition
stages accompanied by the release of distinguished moie-
ties: in the first stage (ambient–330 "C), the observed
sudden mass loss (DTG peak at 250 "C) of 39.0 % coin-
cides well with the release of one salicylaldehyde ligand
{L} with theoretical mass loss of 40.23 %. The melting or
decomposition point of the compound (251–256 "C),
measured with a capillary tube apparatus in air, coincides
with the decomposition maximum at the DTG curve,
although it is not so obvious on the DTA curve. In the
second stage (330–380 "C, DTG peak at 375 "C), mass
loss of 4.5 %, is attributable to the elimination of the CH3
group with calculated value of 4.47 %. The third stage
(380–600 "C) gives gradually a mass loss of 9.0 % which
cannot be attributed to any particular species, because of
uncompleted pyrolysis at 600 "C.
The total mass loss is the same for all the studied com-
pounds (*50 %), and the black solid (residue) at 600 "C is
attributed to carbonaceous zinc oxide (ZnO ? C). The the-
oretical values for the ZnO are 18.0, 17.2, and 23.7 % for the
complexes (1), (2), and (3), respectively. This kind of residue
(ZnO and unpyrolized compounds as organic part) has been
observed in analogous zinc complexes with the Schiff base
5-bromosalycilaldehyde isonicotinoylhydrazone, even at
higher temperatures [28].
Kinetic analyses
Inorder to determine the kinetic mechanisms of decom-
position for the studied materials, the TG curves were
carried out at the four heating rates (5, 10, 15, and
20 "C min-1), confirming that (as expected) for all the
steps of mass loss occurring in the three complexes
investigated, the onset decomposition temperatures shifted
toward higher temperatures with increasing b.
In each TG experiment (carried out at constant heating
rate) for each single step of mass loss at a given temper-
ature T, the extent of conversion value is obtained from the
relation:
a Tð Þ ¼ mi % m Tð Þ½ '= mf % mið Þ ð7Þ
where, mi and mf are the initial and final sample masses,
respectively, while m(T) is the sample mass at a given
temperature. From the plots, the values of a(T) versus
temperature at each of the four heating rates considered
(not shown), the temperatures at which a given sample
reaches a given extent of conversion at a fixed heating rate
(Ta,b) are calculated. From the slope of each regression line
obtained by plotting the left-hand side of Eq. (6), against
Table 4 Selected bond lengths and angles for [Zn(5-NO2-salo)2
(CH3OH)2]
Bond lengths/Å Bond angles/"
Zn(1)–O(1) 2.0394(11) O(1)–Zn(1)–O(1a) 180.00
Zn(1)–O(2) 2.0508(12) O(1)–Zn(1)–O(2) 89.59(5)
Zn(1)–O(3) 2.1749(13) O(1)–Zn(1)–O(2a) 90.41(5)
C(1)–C(2) 1.423(2) O(2)–Zn(1)–O(2a) 180.00
C(1)–C(6) 1.437(2) O(1)–Zn(1)–O(5) 89.89(5)
C(1)–O(1) 1.292(2) O(1)–Zn(1)–O(5a) 90.11(5)
C(2)–C(3) 1.367(3) O(2)–Zn(1)–O(5) 87.22(5)
C(3)–C(4) 1.404(3) O(2)–Zn(1)–O(5a) 92.78(5)
C(4)–C(5) 1.362(3) O(5)–Zn(1)–O(5a) 180.00
C(4)–N(1) 1.458(2)
C(5)–C(6) 1.406(2)
C(6)–C(7) 1.441(2)
C(7)–O(2) 1.232(2)
C(8)–O(5) 1.426(3)
O(3)–N(1) 1.219(2)
O(4)–N(1) 1.227(2)
0 100 200 300 400 500 600
80
40
0
0
–10
–20
–30
–40
–50
DTG
TG
Exo
DTA
Endo
0
–1
–2
–3
Temperature/°C
M
as
s 
lo
ss
/%
D
T
G
/%
m
in
–1
H
ea
t f
lo
w
/
V µ
Fig. 5 TG/DTG–DTA curves of [Zn(5-Cl-salo)2(CH3OH)2] in nitro-
gen at 5 "C min-1
0
–10
–20
–30
–40
–50
–60
M
as
s 
lo
ss
/%
0 100 200 300 400 500 600
Temperature/°C
DTG
TG
Exo
DTA
Endo
0
–2
–4
–6
D
T
G
/%
m
in
–1
80
120
40
0
H
ea
t f
lo
w
/
Vµ
Fig. 6 TG/DTG–DTA curves of [Zn(5-NO2-salo)2(CH3OH)2] in
nitrogen at 5 "C min-1
Characterizations of zinc(II) complexes with salicylaldehydes 461
123
the reciprocal temperature at given extent of conversion at
a fixed heating rate b, Ta,b
-1, the corresponding Ea value at
each extent of conversion a is calculated using both the
OFW [where B = 0 and C = 1.052 in Eq. (6)] and the
KAS approaches [where B = 2 and C = 1 in Eq. (6)].
As it is recognized that the results derived by the KAS
method should be more reliable [15], a comparison of
results was made by plotting EKAS versus EOFW at each
extent of conversion for each decomposition step of [Zn(5-
CH3-salo)2].
1st step: EKAS/kJ mol-1 = (0.991 ± 0.005) EOFW/kJ
mol-1 - (5.1 ± 0.5);
2nd step: EKAS/kJ mol-1 = (0.9975 ± 0.0005) EOFW/kJ
mol-1 - (7.8 ± 0.2); and
3rd step: EKAS/kJ mol-1 = (0.999 ± 0.002) EOFW/kJ
mol-1 - (11.4 ± 0.5).
The goodness of the three linear fits is always excellent,
as well as the closeness of the slopes to unity: The null
hypothesis confirmed (at a confidence level of 95 %) that
the slopes of the three regression lines do not differ from 1.
On the contrary, using the same statistical criterion at the
same confidence level, it was found that intercepts are
always significantly different from 0.
These results demonstrated that the two kinetic methods
provided the same dependence of activation energy from
the extent of conversion, and the slight differences found
between the EKAS and the EOFW values (at each extent of
conversion) are, however, within the associated uncer-
tainties (around 6–7 % of relative deviation). As a result,
the reliability of E data obtained by the two methods being
comparable, the expected variations of activation energy
with the extent of conversion a, for each decomposition
step of the three complexes tested as reported in Fig. 8a–c,
are related to the results obtained with OFW method only.
The trends confirm that activation energies associated to all
decomposition processes cannot be considered constant in
the whole range of values a, thus revealing the expected
complex nature of the decomposition process. Slight vari-
ations are observed only in the first step in the range of a
between 0.15 and 0.90 and, in the third step in the range of
a between 0.10 and 0.60. However, although activation
energies associated to decomposition steps often vary
remarkably with the increasing degree of conversion, no
evident intersections are clearly found in these trends.
These results enabled us to conclude that for the whole
range of extent of conversion, the following scales of
activation energies, and to a certain extent, of thermal
stability, can be assessed:
First step: Cl\NO2\CH3, Second step: Cl\CH3
\NO2, Third step: NO2\CH3\Cl
0
–10
–20
–30
–40
–50
M
as
s 
lo
ss
/%
0 100 200 300 400 500 600
Temperature/°C
0
–2
–4
–6
D
T
G
/%
m
in
–1
80
60
100
120
40
20
0
H
ea
t f
lo
w
/
V
DTG
DTG
TG
Exo
DTA
Endo
µ
Fig. 7 TG/DTG–DTA curves of [Zn(5-CH3-salo)2] in nitrogen at
5 "C min-1
120
140
100
80
60
700
500
300
300
100
500
100
0.0 0.2 0.4 0.6 0.8 1.0
Cl
CH3
NO2
Cl
CH3
NO2
Cl
CH3
NO2
E
/k
J 
m
ol
–1
E
/k
J 
m
ol
–1
E
/k
J 
m
ol
–1
a
b
c
α
Fig. 8 Conversion dependence of activation energy for the decom-
position of all complexes tested using the OFW method: a first
decomposition step, b second step, and c third step
462 A. Zianna et al.
123
In this case, these ‘‘kinetic’’ stability scales are in a very
good agreement with those obtained using the onset TG
temperature. On the other hand, the first step (at lower
temperatures) is the most important in assessing a stability
scale to a homologous series of compounds. According to
this, it can be stated that [Zn(5-CH3-salo)2], which is the
complex in which methanol is absent, seem to have the
highest thermal stability. The data collected at this moment
are not sufficient to establish clearly if the absence of
methanol plays a fundamental role in the stability of this
class of complexes, and hence, further investigation is
needed.
Conclusions
Three new neutral complexes, with the formulae [Zn(X-
salo)2(CH3OH)n], (n = 0 or 2), were prepared and char-
acterized. Their IR and 1H-NMR spectra suggested a
bidentate anionic coordination mode of the salicylaldehyde
ligand through the carbonyl and the phenolic oxygen
atoms. The octahedral arrangement of the ligands around
zinc(II) metal ion was verified by the single-crystal X-ray
diffraction analysis for two of the three.
Their thermal decomposition profiles (by simultaneous
TG/DTG–DTA technique) are similar, presenting sudden
mass loss attributable to the elimination of the coordinated
methanol in the first stage at around 100 "C, followed by
the elimination of the salicylaldehyde or its fragments at
higher temperatures. The decomposition of the complexes
is not completed in nitrogen atmosphere up to 600 "C, and
the solid material found at this temperature is a mixture of
carbonaceous zinc oxide.
Finally, the kinetic analysis of the decomposition processes
was performed by applying both the isoconversional OFW
and theKASmethods.The remarkablevariationsof activation
energy with the extent of conversion associated to each
decomposition process confirms its complex nature, avoiding
the determination of average values of Arrhenius parameters
(activation energy and pre-exponential factor) as well as a
simple way to select a proper model function (and conse-
quently an algorithm describing the reaction mechanism).
Furthermore, although activation energy varies significantly
with the extent of conversion, no evident intersections are
clearly found among the E(a) curves of all the decomposition
steps investigated for the three complexes tested.
Supplementarydata
Detailed crystal data and structure refinement for com-
plexes [Zn(5-Cl-salo)2(CH3OH)2] (1) and [Zn(5-NO2-salo)2
(CH3OH)2] (2) have been deposited with the Cambridge
Crystallographic Data Centre under No CCDC 891356 (1)
and No CCDC 892558 (2).
Copies of this information may be obtained free of
charge from the Director, CCDC, 12 Union Road, Cam-
bridge, CB2 IEZ, UK (fax: ?44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
References
1. Vallee BL, Auld DS. New perspective on zinc biochemistry: co-
catalytic sites in multi-zinc enzyme. Biochemistry. 1993;32(26):
6493–500.
2. Prasad RN, Agrawal A. Synthesis and spectroscopic studies
of mixed ligand complexes of cobalt(II) with salicylaldehyde,
hydroxyarylketones and beta-diketones. J Indian Chem Soc.
2006; 83(1):75–7.
3. Hussain ST, Ahmad H, Atta MA, Afzal M, Saleem M. High
performance liquidchromatography (HPLC), atomic absorption
spectroscopy (AAS) and infrared spectroscopy determination and
solvent extraction of uranium, using bis(salicylaldehyde) pro-
pylene diamine as complexing agent. J Trace Microprobe Tech.
1998;16(2):139–49.
4. Yang Y-M, Lu P-C, Zhu T-T, Liu C-H. Bis(2-formylphenolato-
j2 O, O0)iron(II). Acta Crystallogr. 2007;E63(6):m1613.
5. Wang Q, Wang D-Q. Aquabis(o-vanillinato-j2O, O0)nickel(II).
Acta Crystallogr. 2008;E64:m298.
6. Pessoa JC, Cavaco I, Correira I, Tomaz I, Duarte T, Matias PM.
Oxovanadium(IV) complexes with aromatic aldehydes. J Inorg
Biochem. 2000;80(1):35–9.
7. Lalia-Kantouri M, Papadopoulos CD, Hatzidimitriou AG, Skou-
lika S. Hetero-heptanuclear (Fe–Na) complexes of salicylalde-
hydes: crystal and molecular structure of [Fe2(3-OCH3-salo)8Na5]
3OH!8H2O. Struct Chem. 2009;20(2):177–84.
8. Lalia-Kantouri M, Dimitriadis T, Papadopoulos CD, Gdaniec M,
Czapik A, Hatzidimitriou AG. Synthesis and structural charac-
terization of iron(III) complexes with 2-hydroxyphenones.
Z Anorg Allg Chem. 2009;635(13):2185–90.
9. Krajnı0kova0 A, Györyova0 K, Kova0 řova0 J, Huba0čkova J,
Hudecova0 D, Huba0čkova0 J, El-Dien FN, Koman M. Thermo-
analytical, spectral and biological study of 4-bromobenzoato
zinc(II) complexes containing bioactive organic ligands. J Therm
Anal Calorim. 2012. doi:10.1007/s10973-012-2299-1.
10. Findora0kova0 L, Györyova0 K, Hudecova0 D, Mudroňova0 D,
Kova0 řova0 J, Homzova0 K, Nour El-Dien FA. Thermal decom-
position study and biological characterization of zinc(II) 2-chlo-
robenzoate complexes with bioactive ligands. J Therm Anal
Calorim. 2012; doi:10.1007/s10973-012-2275-9
11. Bujdošová Z, Györyová K, Kovářová J, Hudecová D, Halás L.
Synthesis, biological and physicochemical properties of zinc(II)
salicylate and 5-chlorosalicylate complexes with theophylline and
urea. J Therm Anal Calorim. 2009;98:151–9.
12. Lambi JN, Nsehyuka AT, Ebbewatt N, Cafferata LFR, Arvia AJ.
Synthesis, spectral properties and thermal behaviour of zinc(II)
acetylsalicylate. Thermochim Acta. 2003;398:145–51.
13. Papadopoulos C, Kantiranis N, Vecchio S, Lalia-Kantouri M.
Lanthanide complexes of 3-methoxy-salicylaldehyde: thermal
investigation by simultaneous TG/DTG–DTA coupled with MS;
Thermal decomposition kinetics. J Therm Anal Calorim. 2010;
99:931–8.
Characterizations of zinc(II) complexes with salicylaldehydes 463
123
http://www.ccdc.cam.ac.uk
http://dx.doi.org/10.1007/s10973-012-2299-1
http://dx.doi.org/10.1007/s10973-012-2275-9
14. Materazzi S, Vecchio S, Wo LW, De Angelis Curtis S. Ther-
moanalytical studies of imidazole-substituted coordination com-
pounds. Mn(II)-complexes of bis(1-methylimidazol-2-yl)ketone.
J Therm Anal Calorim. 2011;103:59–64.
15. Vyazovkin S, Burnham AK, Criado JM, Pérez-Maqueda LA,
Popescu C, Sbirrazzuoli N. ICTAC kinetic committee recom-
mendations for performing kinetic computations on thermal
analysis data. Thermochim Acta. 2011;520:1–19.
16. Ozawa T. A new method of analyzing thermogravimetric data.
Bull Chem Soc Japan. 1965;38:1881–6.
17. Flynn JH, Wall LA. A quick direct method for the determination
of activation energy from thermogravimetric data. J Polym Sci B
Polym Lett. 1966;4(5):323–8.
18. Akahira T, Sunose T. Paper no. 246, 1969 Research report, Trans.
joint convention of four electrical institutes. Chiba Inst Technol
(Sci. Technol.) 1971;16:22–31.
19. Agilent Technologies, program CrysAlis PRO ver.1.171.35.
Yarnton, Oxfordshire, England. 2011.
20. Sheldrick GM. A short history of SHELX. Acta Crystallogr.
2008;A64:112–22.
21. Betteridge PW, Carruthers JR, Cooper RI, Prout K, Watkin DJ.
CRYSTALS version 12: software for guided crystal structure
analysis. J Appl Crystallogr. 2003;36:1487.
22. Doyle CD. Estimating isothermal life from thermogravimetric
data. J Appl Polym Sci. 1962;6(24):639–42.
23. Silverstein RM, Bassler GC, Morvill G. Spectrometric identifi-
cation of organic compounds. 6th ed. New York: Wiley; 1998.
24. Nakamoto K. Infrared and Raman spectra of inorganic and
coordination compounds. 5th ed. New York: Wiley; 1997.
25. Binil PS, Anoop MR, Suma S, Sudarsanakumar MR. Growth,
spectral, and thermal characterization of 2-hydroxy-3-methox-
ybenzaldehyde semicarbazon. J Therm Anal Calorim. 2012;. doi:
10.1007/s10973-012-2601-2.
26. Watanabe Y, Aritake Y, Akitsu T. Diaquabis(2,4-dichloro-6-
formylphenolato)zinc(II)-bis(l-2,4-dichloro-6-for-
mylphenolato)bis[aqua(2,4-dichloro-6-formylphenolato)zinc(II)]
(2/1). Acta Crystallogr. 2009;E65:m1640–1.
27. Chen X-M, Zhang S-H, Jin L-X, Z Liu, Yan Y. Diaquabis(2,4-
dibromo-6-formylphenolato- j2 N,N’)zinc(II). Acta Cryst. 2007;
E63: m1321.
28. Dianu LM, Kriza A, Musuc AM. Synthesis, spectral character-
ization, and thermal behavior of mononuclear Cu(II), Co(II),
Ni(II), Mn(II), and Zn(II) complexes with 5-bromosalycilalde-
hyde isonicotinoylhydrazone. J Therm Anal Calorim. 2012;. doi:
10.1007/s10973-012-2578-x.
464 A. Zianna et al.
123
View publication statsView publication stats
http://dx.doi.org/10.1007/s10973-012-2601-2
http://dx.doi.org/10.1007/s10973-012-2578-x
https://www.researchgate.net/publication/257616165
	Synthesis, thermal analysis, and spectroscopic and structural characterizations of zinc(II) complexes with salicylaldehydes
	Abstract
	Introduction
	Experimental
	Materials and synthesis of the complexes [Zn(X-salo)2(CH3OH)n]
	Instruments and methods
	X-ray crystal structure determination
	Theory for kinetic analysis
	Results and discussion
	General considerations and spectroscopic characterization
	Crystal structure of [Zn(5-Cl-salo)2(CH3OH)2]
	Crystal structure of [Zn(5-NO2-salo)2(CH3OH)2]
	Thermal decomposition
	TG/DTG--DTA in nitrogen
	Kinetic analyses
	Conclusions
	Supplementary data
	References