Synthesis and characterization of new mannich base ligand ...

Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
CODEN (USA): AJBPAD

A J B P Rsian ournal of iochemical and harmaceutical esearch

Synthesis and characterization of new mannich base ligand (sap) and Co (II), Ni(II),
Cu(II) AND Zn(II) metal complexes

M. Paul Johnpeter1, A. Paulraj1*, M. Yosuva Suvaikin2 and S.R. Bheeter1

1 Department of Chemistry, St. Joseph’s College, Tiruchirappalli-620 002, Tamil Nadu, India.
2 Department of Chemistry, Arignar Anna Government Arts College, Namakkal-637 002, Tamil Nadu, India

Received: 01 December 2015; Revised: 14 December 2015; Accepted: 22 December 2015

Abstract: A new mannich base of 2-hydroxy (phenyl amino methyl) isoindoline-1,3-dione (SAP) and
its some metal complexes (Co(II), Ni(II), Cu(II) and Zn(II)) have been synthesized and characterized.
Their structural data have been established on the basis of analytical, molar conductance, magnetic,
infrared, ultra-violet, mass, 1H and 13C NMR. The TGA/DTA patterns of a selected few compounds
were recorded and discussed. On the basis of colour, magnetic moments and electronic spectral data,
the geometries of Co(II), Ni(II), Cu(II) and Zn(II) complexes have been assigned.

Key words: Mannich base, 1H & 13C NMR, Mass, Metal complexes, Thermal analysis.

INTRODUCTION:

Synthesis of coordination compounds using organic ligand is one of the most developing,
expanding and successful branches of science. Synthetic organic chemistry has been attaining
enormous growth, not only in terms of carbon-carbon and carbon-hetero atom bonds but also in terms
of development of new strategies, reagents, catalysts, transformations and technologies for the past 15
years. Mannich bases have played a vital role in the development of synthetic organic chemistry [1-6].
The compounds containing aldehyde, amine and amide moiety as a functional group have been found
to possess donor properties and exhibit a wide range of biological activities[7-9]. Having these facts in
mind and continuing efforts on mannich base, in the present work mannich base was derived from the
condensation of salicylaldehyde, aniline and phthalimide and its metal complexes of Co(II), Ni(II),
Cu(II) and Zn(II) were synthesized and characterized using different analytical and spectral
techniques.

EXPERIMENTAL

Chemicals and methods: All chemicals like salicylaldehyde, aniline, phthalimide and various metal
salts and solvents used were analytical grade (AR) Merck products and were used as such without
further purification. The elemental analyses of carbon, hydrogen, nitrogen and oxygen (C,H,N,O) were
carried out at the elemental analyzer namely elemental model ratio EL(III), CECRI - Karaikudi. Metal
analysis had been done using atomic absorption spectrophotometer, Varian model SPECTRAA 220,
CECRI - Karaikudi. Infrared spectra were measured using KBr pellets with Perkin Elmer RX1
Spectrophotometer in the conventional range of 4000 - 400cm-1. The electronic absorption spectra of
the complexes were recorded using a Perkin Elmer Lambda 35 Spectrophotometer in the range of 400
- 800nm. Magnetic susceptibility measurement on powder samples were carried out by the Guoy

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Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
CODEN (USA): AJBPAD

method [10]. The mass spectral study of the ligand was carried out using JEOL D - 300(EI) mass
spectrometer. 1H and 13C NMR spectra of the free ligand and its Zinc (II) complex in DMSO - d6
were recorded in a BRUKER, Switzerland Avance 400 MHz NMR Spectrometer using
tetramethylsilane as internal standard [11].

Synthesis of mannich base: 2 - hydroxy (phenyl amino methyl) isoindoline - 1,3 - dione (SAP) is
commonly known as N - hydroxy (phenyl amino methyl) phthalimide. It was prepared by the mannich
condensation of phthalimide, salicylaldehyde and aniline. Phthalimide (1.471g) was dissolved in
ethanol and aniline (0.9115mL), salicylaldehyde (1.066mL) were added with constant stirring at room
temperature. The oily solution was solidified within an hour and the yellow colour solid product was
formed. It was washed with diethyl ether and recrystallized from ethanol (yield 78%). It melts at 90C.
The formation of the new mannish base (SAP) is shown in Scheme - 1.

Synthesis of metal complexes : Hot ethanolic solution (20mL) of the mannich base ligand (0.01M)
was added to a hot ethanolic solution (20mL) of the metal salt (0.01M) taken in a 100ml beaker with
constant stirring. The reaction mixture was refluxed for 5 - 6 hours. The resulting solution was
concentrated and the complex was recrystalized. The solid product obtained was filtered, washed with
ethanol and dried under vacuum over anhydrous CaCl2 (yield : 65-75%).

RESULTS AND DISCUSSION:

Elemental analysis, colour, molar conductance, electronic spectra and magnetic susceptibility of
the ligand and the complexes: The synthesized ligand and all the metal complexes are quite air
stable, non hygroscopic and insoluble in water but are readily soluble in ethanol, DMF and DMSO.
The colour, analytical data, molar conductance, magnetic moments and electronic spectral value of the
new ligand and metal complexes are given in Table - 1.

Infrared spectra of ligand (SAP) and metal complexes: The characteristic IR absorption bands of
the free ligand (SAP) have been compared with those of the metal complexes in order to get
information regarding the actual donor atom sites of the coordinated ligand molecules. The significant
IR absorption frequencies measured for the metal complexes are provided in Table - 2. The sharp
absorption band observed at 3367cm-1 in the spectrum of the free ligand is ascribed to the aniline
moiety another absorption band observed at 1618cm-1 in the spectrum of the free ligand is ascribed to
the presence of carboxyl (C=O) group in the amide moiety. The shift of both frequency to lower level
confirmed the coordination of the aniline nitrogen (N-H) and carbonyl oxygen of amide (C=O) part of
the ligand respectively. The new bands around at 750,700 and 540cm-1 in the spectra of the metal
complexes were assigned to M-O ,M-N and M-X stretching vibrations respectively.

1H and 13C NMR spectral studies of ligand (SAP) and Zn (II) complex: Evidence for the bonding
mode of the ligand is also provided by the 1H and 13C NMR spectra of the mannich base and Zn(II)
complex in DMSO - d6 which were recorded in a BRUKER, Switzerland Avance 400 MHz. The
following signals are given in Tables - 3 and 4.

The peak at 6 ppm is attributed to the N-H group present in aniline. The shift in the position
of the N-H proton in the Zn (II) complex confirms that nitrogen of the aniline part is coordinated to the
metal ion. The signal due to phthalimide carbonyl carbon (C=O) was also shifted slightly to downfield.

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Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
CODEN (USA): AJBPAD

Therefore, it is concluded that the mannich base behaves as a neutral bidentate ligand in all the
complexes.

Mass fragmentation pattern: Mass (m/z): 334 and (M+ peak),Further fragmentation pattern of the
molecular ions structure of the ligand confirms in Scheme - 2.

Thermal analysis:The Thermo Gravimetric Analysis was done using mass spectrometer in the
temperatures ranging 0-600C at the rate of 10C/min. The thermal decomposition of the material at
different temperatures was studied using Differential Thermal Analysis (DTA). TGA and DTA data of
synthesized complex of SAP.CoCl2 are shown in Fig. 4. The SAP.CoCl2 complex is stable up to
151C. The weight loss between150 - 400C signifies the elimination of organic ligand to form
intermediate of CoCl2. The CoCl2 intermediate undergoes decomposition above 480C. When heated
above 500C the CoCl2 can be decomposed to CoO. The elimination of organic molecule is supported
by the appearance of an endothermic DTA peak at 217C.

CONCLUSION:

The synthesized various substituted compounds of 2-hydroxy (phenyl amino methyl)
isoindoline-1,3-dione (SAP) and Co(II), Ni(II), Cu(II) and Zn(II) metal complexes were synthesized
and characterized. The structural data established on the basis of elemental analysis (C,H,N,O), infra
red, ultra violet, 1H & 13C NMR, mass, magnetic susceptibility and TGA & DTA patterns of
complexes were recorded and discussed.

ACKNOWLEDGEMENT:

The author M. PAUL JOHNPETER acknowledges the Principal and Management of St.
Joseph’s College, Trichirappalli and is very much thankful to Dr. S.R. Bheeter, Dr. A. Paulraj and Dr.

M. Yosuva Suvaikin for their support and encouragement. The author also thank SJC (ACIC), IIT
Madras, CECRI - Karaikudi for the use of their instrumentation facilities.

NH2

CHO O

HN

OH - H2O

O

O

NH
CN
H

OH O

Scheme - 1: Formation of mannich base (SAP)

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Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
CODEN (USA): AJBPAD

NH O m/z = 344
CH N

OH O

NH O m/z = 297
CH
N
OH CH2+

O

O m/z = 251
NH m/z = 198
+CH N

O

NH
+CH
OH

CH+ m/z = 95
OH

CH+

m/z =79

Scheme - 2: Mass fragmentation paAtCtIeCrn of ligand (SAP)
St.Joseph's College ( Autonomous)
T r ic h y- 2

Spectrum Name: IR-SAP-L.sp

100.0

95

90 1885.30
3878.16 1847.94

85 1953.50

80 439.04

75

70 978.37
1027.30 895.57
65
2362.97

60

1073.95

55 522.03
566.88
812.06

50 2890.08
%T 2788.62

45 3314.87
3147.93
40

35 1185.27
1144.82

30 1449.75

25 1485.98 754.97
689.88
1275.71 629.22

20 1661.32 1402.38

1581.87

15 1615.72

10

5

0.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
4000.0

cm -1

Fig. 1: Infrared spectrum of ligand (SAP)
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CODEN (USA): AJBPAD

Fig. 2: 1H NMR spectrum of ligand (SAP)

Fig. 3: 13C NMR spectrum of ligand (SAP)
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Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
CODEN (USA): AJBPAD

Fig. 4: TGA/DTA pattern of SAP.CoCl2.

H2O

Cl Cl Cl Cl
M M

NH O NH O
CH N
H2O

CH N

OH O OH O

Fig. 5: Structure of SAP.MCl2 Fig. 6: Structure of SAP.MCl2
M = Co
M = Ni, Cu, Zn

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Asian Journal of Biochemical and Pharmaceutical Research Issue 4 (Vol. 5) 2015 ISSN: 2231-2560
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Table - 1. Elemental analysis, colour, molar conductance, electronic spectra and magnetic susceptibility
of the ligand and the complexes

Mol. Absorption Transition Calculated / (Founded) µ eff Molar
Weight Maxima Assignment (BM) Cond.
Compound Mol. Formula Yield Colour

C HN O M Cl

73.2 4.7 8.1 13.9

SAP C21H16N2O3 344 - - 78 - - Yellow - -
46
15320 (73.4) (4.5) (8.0) (13.8)
16448
SAP.CoCl2 C24H28Cl2CoN2O5 554 4T1g(F)4T1g(P) 52 5.1 5.1 14.4 10.6 12.8 4.7
4T1g(F)4A2g 65 Violet

(52.5) (5.0) (5.1) (14.1) (10.3) (12.6)

SAP.NiCl2 C24H28Cl2N2NiO5 553 16324 3A2g3T1g(F) 67 52 5.1 5.0 14.4 10.6 12.8 Pale 2.8 21
27920 3A2g3T1g(P) (52.1) (4.9) (5.1) (14.2) (10.5) (12.7) green 28

SAP.CuCl2 C24H28Cl2CuN2O5 559 19663 2Eg2T2g 51.5 5.0 5.0 14.3 11.3 12.7 1.7
24064 68 Block
Charge Transfer
(51.8) (4.9) (5.0) (14.2) (11.5) (12.8)

SAP.ZnCl2 C24H28Cl2N2O5Zn 561 - - 67 51.4 5.0 5.0 14.2 11.6 12.6 Pale Dia 36
(51.7) (5.0) (5.0) (14.0) (11.5) (12.6) yellow

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Table - 2. IR spectral data of ligand (SAP) and metal complexes

Compound C=O N-H O-H M-O M-N M-X

SAP 1618 3367 3172 - - -

SAP.CoCl2 1610 3320 3187 764-754 687-707 525-542
SAP.NiCl2 1611 3353 - 764-753 687-691 525-539
SAP.CuCl2 1607 3335 764-755 687-714 525-534
SAP.ZnCl2 1615 3334 3172 764-754 687-709 525-536
3157

Table - 3. 1H NMR spectral data of ligand (SAP) and Zn(II) complex

Compound Aliphatic Aromatic O-H N-H
C-H (ppm) C-H (ppm) (ppm) (ppm)

SAP 2.5 6.9-8 8.9 6
5.7
SAP.ZnCl2 2.5 6.9-8 8.9

Table - 4. 13C NMR spectral data of ligand (SAP) and Zn(II) complex

Compound Aliphatic Carbon Aromatic Carbonyl Carbon
(ppm) Carbons (ppm) (ppm)

SAP 55 110-140 171

SAP.ZnCl2 55 110-140 165

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Corresponding Author: A. Paulraj, Department of Chemistry, St. Joseph’s College, Tiruchirappalli-620
002, Tamil Nadu, INDIA.

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