научная статья по теме SYNTHESIS, STRUCTURE, AND ANTIMICROBIAL ACTIVITY OF A CADMIUM(II) COMPLEX DERIVED FROM N,N-BIS(5-CHLOROSALICYLIDENE)PROPANE-1,3-DIAMINE Химия

Текст научной статьи на тему «SYNTHESIS, STRUCTURE, AND ANTIMICROBIAL ACTIVITY OF A CADMIUM(II) COMPLEX DERIVED FROM N,N-BIS(5-CHLOROSALICYLIDENE)PROPANE-1,3-DIAMINE»

КООРДИНАЦИОННАЯ ХИМИЯ, 2012, том 38, № 1, с. 26-30

УДК 41.49

SYNTHESIS, STRUCTURE, AND ANTIMICROBIAL ACTIVITY OF A CADMIUM(II) COMPLEX DERIVED FROM N,N'-£/s(5-CHLOROSALICYLIDENE)PROPANE-1,3-DIAMINE

© 2012 L. W. Xue*, Y. J. Han, G. Q. Zhao, and Y. X. Feng

College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan Henan 467000, P.R. China

*E-mail: pdsuchemistry@163.com Received February 11, 2011

The Schiff base, N,N'-bis(5-chlorosalicylidene)propane-1,3-diamine (H2L) derived from 5-chlorosalicylalde-hyde and propane-1,3-diamine, and its cadmium(II) complex, bis(p.2-acetato)bis(p.2-N,N'-bis(5-chlorosali-cylidene)-1,3-propanediamine)tricadmium(II) Cd[Cd(CH3COO)L]2 (I), have been prepared and characterized by elemental analyses, IR, and single-crystal X-ray difdfraction analysis. The crystal of H2L is monoclinic: space group P21/n, a = 11.252(4), b = 8.972(3), c = 16.981(6) А, в = 96.005(4)°, V = 1705.0(10) A3, Z = 4. The crystal of complex I is monoclinic: space group P2j/c, a = 11.056(1), b = 22.284(2), c = 8.398(1) A, в = 91.779(1)°, V = 2068.0(3) A3, Z = 2. Complex I is a centrosymmetric trinuclear cadmium(II) complex. The deprotonated Schiff base ligand coordinates to the Cd atoms through the phenolate O and imine N atoms. The effect of the Schiff base ligand and the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.

INTRODUCTION

Schiff bases are a kind of versatile ligands in coordination chemistry [1—3]. In recent years, metal complexes of Schiff bases have attracted considerable attention due to their remarkable biological activity, such as antifungal, antibacterial, and antitumor [4—6]. It has been shown that the Schiff base complexes derived from salicylaldehyde and its derivatives with primary amines have interesting biological activity [6—8]. The Schiff base H2L has been first reported by Shi and coworkers [9]; however, the search in the Cambridge Crystallo-graphic Database (version 5.31 with addenda up to August, 2010) [10] has revealed that there only four Mn [11-14], one Cu [15], two Ni [16], one Co [17], and one Cr [18] complexes derived from H2L have been reported, and no cadmium(II) complexes with L have been reported so far.

Cl

Cl

(H2L)

In the present paper, the preparation, characterization, and antimicrobial activity of a new cadmium(II) complex derived from H2L are reported.

N) analyses were made on a PerkinElmer Model 240B automatic analyzer. Cadmium analysis was carried out by EDTA titration. IR spectra were recorded on an IR-408 Shimadzu 568 spectrophotometer. X-ray diffraction was carried out on a Bruker SMART 1000 CCD area diffractometer. The Schiff base H2L was prepared according to the literature method [9].

Synthesis of Cd[Cd(CH3COO)L]2 (I).The Schiff base H2L (0.35 g, 1 mmol) was dissolved in methanol (30 ml) to which a methanol solution (20 ml) of Cd(CH3COO)2 • 2H2O (0.27 g, 1 mmol) was added with stirring. The mixture was stirred for 1 h at ambient temperature to give a colorless solution. Colorless block-shaped single crystals suitable for X-ray diffraction were formed by slow evaporation of the solution in air for a few days. The yield was 54% (based on the metal salt used).

IR spectrum (v, cm-1): 1620 s, 1529 m, 1456 s, 1383 m, 1310 m, 1281 m, 1168 m, 1103 w, 1037 w, 975 w, 906 w, 868 w, 821 m, 790 w, 707 m, 647 w, 550 w, 509 w, 474 w, 449 w.

For C38H34Cd3Cl4N4O8

anal. calcd., %: C, 39.56; H, 2.97; N, 4.86; Cd, 29.23. Found, %: C, 39.37; H, 3.03; N, 4.95; Cd, 28.91.

EXPERIMENTAL

Material and methods. 5-Chlorosalicylaldehyde and propane-1,3-diamine were purchased from Fluka. Other reagents and solvents were analytical grade and used without further purification. Elemental (C, H, and

X-ray crystal determination. Data were collected from selected crystals mounted on glass fibers. The data for the Schiff base and the cadmium complex were processed with SAINT [19] and corrected for absorption using SADABS [20]. Semiempirical absorption corrections were applied with y scans [21]. The structures

Table 1. Crystallographic data and structure refinement summary for H2L and complex I

Parameter Value

h2l I

Habit, color Block, yellow Block, colorless

Formula weight 351.2 1153.7

Temperature, K 298(2) 298(2)

Crystal size, mm 0.20 x 0.20 x 0.18 0.32 x 0.30 x 0.30

Radiation (K, Â) Moo (0.71073) Mo^a (0.71073)

Crystal system Monoclinic Monoclinic

Space group P2x/n P2\/c

Unit cell dimensions:

a, Â 11.252(4) 11.056(1)

b, Â 8.972(3) 22.284(2)

c, Â 16.981(6) 8.398(1)

ß, deg 96.005(4) 91.779(1)

V, Â3 1705.0(10) 2068.0(3)

Z 4 2

Pcalcd mg cm-3 1.368 1.853

F(000) 728 1132

Absorption coefficient, mm-1 0.391 1.842

9 Range for data collection, deg 2.08-25.97 2.06-27.00

Index ranges -13 < h < 13, -10 < k < 11, -20 < l < 13 -13 < h < 14,-28 < k < 23, -10 < l < 10

Reflections collected 8969 12006

Independent reflections 3322 4490

Data (I > 2a(I))/parameters 1914/210 3487/260

Final R indices (I > 2a(I)) 0.0419 0.0311

R indices (all data) 0.0987 0.0608

Goodness-of-fit 1.026 1.029

APmax, APmin e â\-3 0.141, -0.213 0.565, -0.409

were solved by direct methods using the SHELXS-97 program and refined by full-matrix least-squares techniques on F2 using anisotropic displacement parameters [22]. Hydrogen atoms were placed at the calculated positions. Idealized H atoms were refined with isotropic displacement parameters set to 1.2 (1.5 for hydroxy and methyl groups) times the equivalent isotropic U values of the parent carbon and nitrogen atoms. The crystallographic data for the Schiff base H2L and complex I are listed in Table 1. Supplementary materials have been deposited with the Cambridge Crystallographic Data Centre (nos. 812227 (H2L) and 812228 (I); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam. ac.uk).

RESULTS AND DISCUSSION

The yellow Schiff base ligand H2L in this paper was prepared by the condensation of 2 : 1 molar ratio of

5-chlorosalicylaldehyde with propane-1,3-diamine in methanol at ambient temperature. The Schiff base prepared in this way was formed in a nearly quantitative yield and was of high purity. Cadmium complex I was readily synthesized by the reaction of the Schiff base ligand and cadmium acetate in methanol at ambient temperature. Both the Schiff base and the cadmium complex are very stable at room temperature in the solid state and are soluble in common organic solvents, such as methanol, ethanol, chloroform, and acetonitrile. The results of elemental analyses are in accord with the composition suggested for the ligand and complex I.

The IR spectra of the Schiff base ligand H2L and cadmium(II) complex I provide information about the metal—ligand bonding. Assignments are based on typical group frequencies. The weak and broad band centered at 3382 cm-1 of the Schiff base is assigned to the v(O-H) vibration, which is absent in complex I, indicating the coordination through the deprotonated form

KOOP,3HHAUHOHHAH XHMH3 tom 38 № 1 2012

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XUE et al.

of the hydroxy groups of the Schiff base ligand. The strong band at 1635 cm-1 in the Schiff base ligand is assigned to the azomethine groups, which is observed at the lower frequency (1620 cm-1) in the complex, indicating the coordination of the azomethine N atoms to the Cd atoms. The bands observed at 1529 and 1456 cm-1 are assigned to the asymmetric and symmetric vibrations of the carboxy groups of the actetate ligands. The bands indicative of the Cd-O and Cd-N vibrations are in the range 440-550 cm-1.

Table 2. Coordinate bond distances (A) and angles (deg) for H2L and complex I

Bond

d, Á

Bond

d, Á

H2L

N(1)-C(7)

N(2)-C(11)

O(1)-C(2)

1.260(3) 1.271(3) 1.340(3)

N(1)—C(8)

N(2)—C(10)

O(2)—C(13)

1.460(3) 1.454(3) 1.344(3)

I

Cd(1)-O(1) 2.239(2) Cd(1)-O(2) 2.217(2)

Cd(1)-O(3) 2.163(3) Cd(1)-N(1) 2.234(3)

Cd(1)-N(2) 2.259(3) Cd(2)-O(1) 2.276(2)

Cd(2)-O(2) 2.274(2) Cd(2)-O(4) 2.335(3)

N(1)-C(7) 1.268(4) N(1)-C(8) 1.467(4)

N(2)-C(11) 1.276(4) N(2)-C(10) 1.479(4)

O(1)-C(2) 1.319(4) O(2)-C(13) 1.313(4)

Angle ro, deg Angle ro, deg

O(3)Cd(1)O(2) 102.89(11) I O(3)Cd(1)N(1) 114.30(11)

O(2)Cd(1)N(1) 142.72(10) O(3)Cd(1)O(1) 112.34(10)

O(2)Cd(1)O(1) 80.41(9) N(1)Cd(1)O(1) 83.07(9)

O(3)Cd(1)N(2) 105.28(11) O(2)Cd(1)N(2) 83.61(9)

N(1)Cd(1)N(2) 89.03(10) O(1)Cd(1)N(2) 141.48(10)

O(2)Cd(2)O(U) 101.60(9) O(2)Cd(2)O(1) 78.40(9)

O(2)Cd(2)O(4) 83.49(9) O(2)Cd(2)O(4^) 96.51(9)

O(1)Cd(2)O(4) 80.53(10) O(1)Cd(2)O(4A) 99.47(10)

The molecular structures of the Schiff base H2L and cadmium(II) complex I are shown in Figs. 1 and 2, respectively. Selected bond distances and angles are listed in Table 2.

There are two intramolecular O—H—N hydrogen bonds in the Schiff base H2L, and the dihedral angle between the two benzene rings is 68.3(3)°. Cadmium complex I derived from the Schiff base ligand H2L is an acetato-bridged centrosymmetric trinuclear cadmi-um(II) compound, which contains two CdL units connected to each other by the completely encapsulated central Cd atom. The Schiff base ligand coordinates to the Cd atom through the phenolate O and imine N atoms. The bond lengths of N(1)=C(7) 1.268(4) and N(2)=C(11) 1.276(4) Á in complex I are slightly longer than those (1.260(3) and 1.271(3) Á) in the Schiff base ligand H2L. The bond lengths of O(1)-C(2) 1.319(4) and O(2)-C(13) 1.313(4) Á in complex I are a little shorter than those 1.340(2) and 1.344(3) Á in the Schiff base ligand.

The central Cd atom is coordinated by four phenolate O and two acetate O atoms, forming a slightly distorted octahedral geometry. The coordinate bond lengths related to Cd(2) atom are in the range 2.274(2)-2.335(3) Á. The greatest deviation of the coordinate bond angles from those expected for an ideal octahedral geometry is found for O(1)Cd(2)O(2) 78.4(1)°, which is caused by the strain created by the four-membered chelate ring Cd(1)O(1)Cd(2)O(2). The coordination around the inversion-related terminal Cd atoms are distorte

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