1. ISSN (Print): 2328-3777, ISSN (Online): 2328-3785, ISSN (CD-ROM): 2328-3793
American International Journal of
Research in Formal, Applied
& Natural Sciences
AIJRFANS 14-271; © 2014, AIJRFANS All Rights Reserved Page 136
Available online at http://www.iasir.net
AIJRFANS is a refereed, indexed, peer-reviewed, multidisciplinary and open access journal published by
International Association of Scientific Innovation and Research (IASIR), USA
(An Association Unifying the Sciences, Engineering, and Applied Research)
Synthesis, Characterisation and Thermal studies of polymeric Cu(II),
Zn(II) and Cd(II) complexes with 4-{(E)-1-(pyrimidin-2-ylimino)ethyl}-6-
((z)-1-(pyrimidin-2-ylimino)ethyl)benzene-1,3-diol and 4-{(E)-1-(p-
tolylimino)ethyl}-6-((z)-1-(p-tolylimino)ethyl)benzene-1,3-diol
L. B. Roya
, Pragya Kumarib
, Madhu Bala*
a
Department of Civil Engineering, National Institute of Technology, Patna-800005,Bihar (INDIA)
b
Department of Life Science (Chemistry), United Institute of Technology, Industrial Area, Nainy, Allahabad,
U.P (INDIA)
*
Department of Chemistry, National Institute of Technology, Patna-800005, Bihar (INDIA)
I. INTRODUCTION
The design of polymeric architecture in coordination compounds by ligand assisted reaction have aroused
considerable interest due to multidimensional utility of polymers in industrial Technology and catalysis[1-3]
. An
additional interest arose when the polydentate bridging ligands possess relevant importance in biological
processes, because their coordination to metal serves as model of reference in Bioinorganic chemistry[4]
. The
most important stereochemical models for biological function and polydentate Schiff bases are considered to be
the important donor molecules for coordination chemistry[5-6]
. The Schiff base ligand containing nitrogen,
oxygen and sulphur donor sites are of prime importance due to their strong ability for formation of coordination
complexes of biological potentiality, catalytic activity and photochromic properties[7-8]
. In present investigation
we have designed quadridentate Schiff bases 4-{(E)-1-(p-tolylimino)ethyl}-6-((z)-1-(p-
tolylimino)ethyl)benzene-1,3-diol (H2bistdb) and 4-{(E)-1-(pyrimidin-2-ylimino)ethyl}-6-((z)-1-(pyrimidin-2-
ylimino)ethyl)benzene-1,3-diol (H2bispdb), capable of forming polymeric complexes with metal ions and
reported the synthesis and characterisation of their Cu(II), Zn(II) and Cd(II) complexes.
II. EXPERIMENTAL
These ligands were prepared by condensing 1,1’
-4,6-dihydroxy-1,3-phenylene)diethanone[8,9]
(acdp) with
appropriate amine, p-tolylamine and 2-aminopyrimidine in 1:2 molar proportion in ethanol containing a few
drops of acetic acid.
Abstract: Polymeric copper(II), zinc(II) and cadmium(II) complexes of polydentate ligand 1,5-bis(2-
pyrimidineaminoethylidene)-2,4-dihydroxy benzene (H2bispdb) and 1,5-bis(p-tolylaminoethylidene)-2,4-
dihydroxy benzene (H2bistdb) of compositions [CuL(H2O)2]n and [ML]n, (M= ZnII
or CdII
and H2L=
H2bispdb or H2bistdb) were synthesised and characterised by analytical results, magnetic susceptibility,
1
HNMR, IR and electronic absorption studies. The thermal stability of zinc(II) and copper(II) complexes
were studied and discussed.
Keywords: Synthesis, Characterisation Polymeric Metal Complexes1,1’
-4,6-dihydroxy-1,3-
phenylene)diethanone Schiff bases

2. L. B. Royet al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp. 136-140
AIJRFANS 14-271; © 2014, AIJRFANS All Rights Reserved Page 137
1,1’
-4,6-dihydroxy-1,3-phenylene)diethanone (acdp) was prepared by Fries rearrangement in anhydrous ZnCl2
on reacting dry acetic anhydride and resorcinol by reported method[8,9]
.
Preparation of Schiff bases
Preparation of H2bistdb and H2bispdb
About 19.5 gm (.01 mole) 1,1’
-4,6-dihydroxy-1,3-phenylene)diethanone was taken in 100 ml ethanol and
refluxed with (0.2 mole) of appropriate amines (p-toludine or 2-aminopyrimidine) for three to four hours on a
steam bath by adding 2 ml acetic acid. The cream yellow Schiff bases began to separate slowly. The refluxate
was concentrated and cooled to ice temperature. The product separated was collected on a filter, washed with
cold ethanol and dried in a dessicator over CaCl2. The dried samples were recrystallised from THF ethanol
mixture (1:1) and dried samples were analysed for carbon, hydrogen and nitrogen contents. The ligand H2bistdb
was found to contain C; 77.22%, H; 6.65%, N; 7.43% and it (C24H24N2O2) requires C; 77.42%, H; 6.45%, N;
7.52%. Melting point recorded 2430
c (uncorrected). The compound H2bispdb was found to contain C; 61.88%,
H; 4.68%, N; 23.96%. The compound H2bispdb (C18H16N6O2) requires C; 62.06%, H; 4.59% and N; 24.14%.
Melting point of H2bispdb recorded 2610
c.
Preparation of complexes [CuL(H2O)2] and [ML]n, (M= Zn2+
or Cd2+
and H2L= H2bistdb or H2bispdb)
About 0.05 mole of metal acetate was dissolved in 30 ml aqueous ethanol and added slowly with stirring to
appropriate ligand (0.05 mole) dissolved in hot THF and ethanol mixture, when tary product separated slowly.
The products were titurated with ether when fine powdered products were obtained. The products were collected
on filter, washed with methanol and ether and dried in a desiccators over CaCl2. The analytical results of
complexes are recorded in Table-A.
Materials and Physical measurements:
All solvents and chemicals used were E.Merck or BDH products. Metal acetates were E.Merck extra pure
chemicals. The magnetic susceptibility of the complexes were determined by Gouy method at room
temperature. The i.r spectra of ligands and their complexes were recorded as KBr optics in the range of 400-
4000cm-1
on Shimadzu 8201 FTIR spectrophotometer at IIT Patna. The electronic absorption spectra of ligands
and their complexes were recorded on Shimadzu U-V 2500 PC series spectrometers. 1
HNMR spectra of ligand
were recorded in DMSO-d6
solution with Brucker AV 300 NMR spectrometer. Mass spectra were recorded on
GEOL G.C Mate spectrometer at IIT Chennai. The results of C, H, N and TG, DTA analyses were obtained
from BIT Mesra, Ranchi.
Table-A: Elemental analysis and physical data of complexes (Molar electrical conductance value in DMF at
310
c)
Compound Colour % Elemental analysis Found (Calc.) Ωαohm-
1
mol-1
cm-2
Metal Carbon Hydrogen Nitrogen
[Cu(bistdb)(H2O)2]n Brick red 13.43(13.53) 61.19(61.33) 5.66(5.54) 6.01(5.96) 4
[Cu(bispdb)(H2O)2]n Brick red 14.17(14.26) 48.31(48.55) 3.82(4.04) 18.62(18.85) 6
[Zn(bistdb)]n Light cream 14.92(15.02) 66.01(66.14) 5.13(5.05) 6.51(6.43) 5
[Zn(bispdb)]n Light cream 15.73(15.89) 52.41(52.50) 3.48(3.40) 20.18(20.41) 3
[Cd2(bistdb)]n Creamyellow 23.18(23.30) 59.53(59.78) 4.69(4.56) 5.94(5.80) 3
[Cd2(bistdb)]n Creamyellow 24.38(24.52) 48.49(48.55) 3.27(3.14) 18.13(18.32) 4
III. RESULTS AND DISCUSSION
The proton NMR spectrum of 4-{(E)-1-(p-tolylimino) ethyl}-6-((z)-1-(p-tolylimino)ethyl)benzene-1,3-diol
(H2bistdb) shows two sharp singlet (1
HNMR-Fig I) located at δ= 2.527 ppm and δ= 4.282 ppm assigned as tolyl
CH3proton and ethylidene proton signals. The multiplets observed in 1
HNMR spectrum of
H2bistdb between (δ= 7.346-7.874 ppm) are assigned as phenyl ring proton signals. The proton signals at δ=
8.001 and 8.027 ppm are attributed to phenolic proton signals. The 1
HNMR spectrum of 4-{(E)-1-(pyrimidin-2-
ylimino)ethyl}-6-((z)-1-(pyrimidin-2-ylimino)ethyl)benzene-1,3-diol (H2bispdb) shows one strong singlet at δ=
4.268 ppm can be assigned to ethylidene CH3 proton signal. The multiplets between δ= 7.105 and 7.935 ppm are
assigned to phenyl and pyrimidine ring (CH) proton signals. The phenolic proton signals of H2bispdb were
observed at δ= 8.145 and 8.195 ppm. The mass determination of ligand H2bistdb shows molecular mass peak
(Fig-M-T-1) at 373 for M+
+1 peak supporting molecular mass 372 for ligand. The base peak at 105 indicated the
formation of toluidine fragment. The mass spectrum of ligand 4-{(E)-1-(pyrimidin-2-ylimino)ethyl}-6-((z)-1-
(pyrimidin-2-ylimino)ethyl)benzene-1,3-diol(H2bispdb) show M+
+1 peak at 349 supporting molecular mass to
be 348. The base peak at 79 indicated the formation of pyrimidine fragment. The mass and 1
HNMR spectra of
ligand H2bistdb and (H2bispdb) are consistent with their assigned structure.

3. L. B. Royet al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp. 136-140
AIJRFANS 14-271; © 2014, AIJRFANS All Rights Reserved Page 138
The ligands are potent quadridentate (N-O) donor coordinating molecules capable of forming bridging group in
polymeric complexes. The elemental analysis of the complexes correspond to composition [CuL(H2O)2]n, (H2L=
H2bistdb or H2bispdb) and [ML]n, (M= ZnII
or CdII
and H2L= H2bistdb or H2bispdb). The complexes are quite
stable in air at elevated temperature. The complexes are insoluble in water, methanol and ethanol but dissolve
appreciably in DMF and DMSO. The complexes partially dissolve in dioxan and THF. The DMF solutions of
complexes are almost non conducting (Ωα = 4-5 ohm-1
mol-1
cm2
) supporting their non ionic characters[10]
. As
expected zinc(II) and cadmium(II) complexes are diamagnetic and copper(II) complexes are paramagnetic. The
effective magnetic moment value of [Cu(bistdb)(H2O)2] and [Cu(bispdb)(H2O)2] at room temperature are 1.87
and 1.89 B.M respectively occur in the range of magnetically dilute distorted octahedral copper(II) complexes[11-
12]
. The electronic absorption spectrum of H2bistdb in ethanol shows electronic bands at 234, 262 and 330 nm
assigned as σ π *, ππ* and nπ* transitions. The ligand H2bispdb shows electronic transitions at 228, 256
and 305 nm assignable as σ π *, ππ* and nπ* transitions. These transitions are obscured in complexes
due to strong charge transfer transitions of complexes. The electronic absorption spectrum of DMF solutions of
zinc(II) and cadmium(II) complexes show strong absorption below 390 nm due to charge transfer absorption.
The Cu(II) complexes [Cu(bistdb)(H2O)2] shows a medium band at 520 nm and weak broad band at 680-690 nm
attributed to 2
B1g2
B2g and 2
B1g2
A1g , 2
Eg transitions. The brick red copper(II) complex [Cu(bispdb)(H2O)2]
shows strong absorption below 400 nm due to charge transfer transition. The medium band at 530-540 nm
observed has been attributed to 2
B1g2
B2g and a broad band at 670-700 nm to 2
B1g2
A1g , 2
Eg transitions.

4. L. B. Royet al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp. 136-140
AIJRFANS 14-271; © 2014, AIJRFANS All Rights Reserved Page 139
The i.r. spectra of ligands and their complexes display characteristic IR vibrations of phenolic OH and
ethylideneimino (C=N) groups. The i.r spectrum H2bistdb shows ν(OH) vibration at 3501 and broad band at
3190-2973 cm-1
due to hydrogen bonded phenolic OH group. The methyl (CH3) group stretching band can be
assigned to i.r. band at 2973 cm-1
. The phenolic group stretching band of ligand disappears in its complexes
supporting deprotonation of (OH) proton on coordination. The ligand (IR-Fig-A3) show ν(C=N) vibration at
1642 cm-1
which is shifted to lower vibrations and observed near 1600±5 cm-1
supporting coordination of ligand
through (C=N) nitrogen. A large number of i.r. bands in finger print region are assigned to phenyl group and
ethylidene part skeletal vibrations.
Diaquo copper(II) complex [Cu(bistdb)(H2O)2] shows a broad strong band at 3409 cm-1
for ν(H2O) vibration
and a medium band at 663 cm-1
for rocking band of coordinated H2O group. The ν(C=N) of ligand was shifted
to lower wave number and located at 1604 cm-1
supporting coordination of (C=N) nitrogen to copper (II).The
ligand H2bispdb shows phenolic group ν(OH) at 3388 cm-1
and broad band near 3195 cm-1
due to hydrogen
bonded phenolic group. The ν(C=N) of ligand (IR-Fig-M2) was observed 1634 cm-1
which is shifted to lower
frequency in almost all complexes and observed at 1600±5 cm-1
. The phenolic group ν(C-O) of H2bispdb was
assigned to a band at 1156 cm-1
which is shifted to higher wave number and observed near 1350±10 cm-1
supporting coordination of deprotonated phenolic oxygen atom.

5. L. B. Royet al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp. 136-140
AIJRFANS 14-271; © 2014, AIJRFANS All Rights Reserved Page 140
The TGA and DTA studies of complexes were performed in the range of 400
-7200
c in static air. The TG curve
of copper(II) complex [Cu(bistdb)(H2O)2] starts loss in weight at 1600
c giving DTA maxima at 1800
c and DTG
peak at the same temperature and give stable product at 2100
c. The weight loss corresponds to 2H2O per copper
atom supporting coordination of both H2O molecule for each copper(II) in complex. The product formed at
2100
c is very stable and remains stable upto 5400
c without loss in weight showing an exothermic DTA maxima
4800
c indicating phase change in complex. The complex started slow decomposition with weight loss and
showing DTG maxima at 5700
c and an exothermic DTA peak at 5750
c. The loss in weight continues upto 6100
c
giving stable product probably CuO. The weight of residue required is 16.94 and observed for formation of CuO
is 17.02%. The TG curve shows that the product [Cu(bispdb)(H2O)2] is also stable upto 1250
c and starts loss in
weight giving DTG maxima at 1700
c and an exothermic DTA peak at 1700
c. The loss in weight continues upto
1900
c giving stable product [Cu(bispdb)]n. The loss incurred is 8.24% and calculated for loss of two coordinated
water is 8.08%. The TG curve shows that product is stable upto 4900
c but shows an exothermic DTA maxima at
3800
c attributable to change in phase structure of complexes. The TG curve shows that on heating after 4900
c
the complex starts decomposes showing an exothermic peak at 5300
c and DTG maxima at 5250
c. The loss
continues giving stable metal oxide at 6000
c. The loss in weight corresponds to expected loss 82.15% for
formation of CuO. The Zn(II) complex, [Zn(bistdb)]n is stable upto 3300
c with an exothermic DTA maxima at
3500
c indicating a phase change forming octahedral environment around metal from tetrahedral one. TG curve
shows that complex starts decomposing slowly after 4400
c giving metal oxide at 520-5300
c. A broad DTA
maxima at 4900
c indicated burning and decomposition of complex between 440-5200
c. The cadmium(II)
complex [Cd(bistdb)]n is also stable to heat below 4200
c with phase change at 3800
c as indicated by an
exothermic DTA maxima. The complex starts decomposing at 4500
c as indicated by weight loss in TG curve.
The complex decomposes completely between 450-520 in static air giving stable metal oxide (CdO). The
observed weight of residue 26.82% corresponds to expected weight of CdO, 26.61%. The decomposition
process is exothermic, showing DTA maxima at 4800
c. The exceptionally high thermal stability of complexes
supported polymeric structure of complexes. The copper(II) complexes have higher stability than Zn(II) and
Cd(II) complexes indicating strong coordination of Cu(II) than that of Zn(II) and Cd(II) complexes. Thus from
the studies of molecular composition and physical data, the following polymeric structure is suggested for
H2bistdb or H2bispdb complexes of Cu(II), Zn(II) and Cd(II).
Conclusion
The ligand H2bistdb and H2bispdb forms thermally stable polymeric complexes with Cu(II), Zn(II) and Cd(II).
These ligand coordinates as N, O, donor chelating molecule forming bridge between metal atoms.
Acknowledgement:
Thanks are due to authority of IIT Patna for IR and UV spectral measurement and B.I.T Mesra for C, H, N
analysis, TG and DTA measurements.
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