КООРДИНАЦИОННАЯ ХИМИЯ, 2013, том 39, № 12, с. 766-770
УДК 541.49
SYNTHESIS, STRUCTURES, AND ANTIMICROBIAL ACTIVITY OF NICKEL(II) AND ZINC(II) COMPLEXES WITH SCHIFF BASES DERIVED FROM 3-BROMOSALICYLALDEHYDE
© 2013 L. W. Xue*, X. W. Li, G. Q. Zhao, and W. C. Yang
College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan Henan, 467000 P.R. China
*E-mail: pdsuchemistry@163.com Received June 13, 2012
The Schiff bases 2-bromo-6-[(3-cyclohexylaminopropylimino)methyl]phenol (HCMP) and 2-bromo-6-[(3-dimethylaminopropylimino)methyl]phenol (HDMP) derived from 3-bromosalicylaldehyde with N-cy-clohexylpropane-1,3-diamine and N,N-dimethylpropane-1,3-diamine, respectively, and their nickel(II) and zinc(II) complexes [Ni(CMP)2] (I) and [ZnCl2(HDMP)] (II) have been prepared and characterized by elemental analyses, IR, and single crystal X-ray crystallographic determination. The crystal of I is monoclin-ic: space group P21/c, a = 12.0304(6), b = 13.1594(6), c = 10.2445(5) А, в = 101.019(1)°, V= 1591.9(1) A3, Z = 2. The crystal of II is monoclinic: space group C2/c, a = 22.286(5), b = 12.210(3), c = 14.513(3) А, в = = 124.118(3)°, V = 3269.5(13) A3, Z = 8. The Schiff base HCMP coordinates to the Ni atom through the phenolate O, imine N, and amine N atoms, while the Schiff base HDMP coordinates to the Zn atom through the phenolate O and imine N atoms. The effect of these complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied.
DOI: 10.7868/S0132344X13110091
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 de-
rivatives with primary amines, bearing the N2O, N2S, NO2 or NSO donor sets, have interesting biological activity [6—10]. To the best of our knowledge, no complexes have been reported with the Schiff bases 2-bromo-6-[(3-cyclohexylamino-propylimino)methyl]phenol (HCMP) and 2-bro-mo-6-[(3-dimethylaminopropylimino)methyl]phenol (HDMP):
In the present paper, the preparation, characterization and antimicrobial activity of new nickel(II) and zinc(II) complexes [Ni(CMP)2] (I) and [ZnCl2(HDMP)] (II) derived from the Schiff bases are reported.
EXPERIMENTAL
Material and methods. 3-Bromosalicylaldehyde, N-cyclohexylpropane-1,3-diamine, and N,N-dime-thylpropane-1,3-diamine were purchased from Fluka.
Other reagents and solvents were analytical grade and were used without further purification. Elemental (C, H, and N) analyses were made on a PerkinElmer Model 240B automatic analyser. Nickel and zinc analyses were carried out by EDTA titration. Infrared (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.
Synthesis of HCMP. The Schiff base ligand HCMP was prepared by the condensation of equimolar quantities of3-bromosalicylaldehyde (0.201 g, 1 mmol) with N-cyclohexylpropane-1,3-diamine (0.156 g, 1 mmol) in methanol (30 mL) at ambient temperature for 1 h. Then the methanol was evaporated by distillation, yielding yellow solid of the Schiff base.
For C16H23N2OBr
anal. calcd., %: C, 56.6; H, 6.8; N, 8.3.
Found, %: C, 56.8; H, 6.9; N, 8.2.
Synthesis of HDMP. The Schiff base ligand HDMP was prepared by the condensation of equimolar quantities of 3-bromosalicylaldehyde (0.201 g, 1 mmol) with N,N-dimethylpropane-1,3-diamine (0.285 g, 1 mmol) in methanol (30 mL) at ambient temperature for 1 h. Then the methanol was evaporated by distillation, yielding yellow solid of the Schiff base.
For C12H17N2OBr
anal. calcd., %: C, 50.5; H, 6.0; N, 9.8.
Found, %: C, 50.4; H, 6.1; N, 9.8.
Synthesis of complex I. The Schiff base HCMP (0.34 g, 1.0 mmol) was dissolved by methanol (20 mL), to which was added with stirring a methanol solution (10 mL) of Ni(CH3COO) • 4H2O (0.25 g, 1.0 mmol). The mixture was stirred for 1 h at ambient temperature to give a green solution. Green block-shaped single crystals suitable for X-ray diffraction were formed by slow evaporation of the solution in air for several days. The yield was 49% (based on HCMP). IR data (v, cm-1): 3272 w, 1625 s, 1539 s, 1475 m, 1438 m, 1423 w, 1387 m, 1254 s, 1225 m, 1113 m, 1083 m, 967 m, 831 m, 733 m, 573 w, 539 w, 462 w.
For C32H44N4O2Br2Ni
anal. calcd., %: C, 52.3; H, 6.0; N, 7.6; Ni, 8.0. Found, %: C, 52.1; H, 6.1; N, 7.7; Ni, 8.2.
Synthesis of complex II. The Schiff base HDMP (0.28 g, 1.0 mmol) was dissolved by methanol (20 mL), to which was added with stirring a methanol solution (10 mL) of ZnCl2 (0.14 g, 1.0 mmol). 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 several days. The yield was 63% (based on HDMP). IR data (v, cm-1): 3251 w, 1626 s, 1603 s, 1536 s, 1485 w, 1437 m, 1422 w, 1396 m, 1351 w, 1297 m, 1223 s, 1120 m, 973 w, 837 m, 735 w, 654 w, 628 w, 572 w, 543 w, 455 w.
For C12H17N2OCl2BrZn
anal. calcd., %: C, 34.2; H, 4.1; N, 6.6; Zn, 15.5. Found, %: C, 34.3; H, 4.0; N, 6.7; Zn, 15.7.
X-ray structure determination. Data were collected from selected crystals mounted on glass fibres. The data for the two complexes were processed with SAINT [11] and corrected for absorption using SADABS [12]. Multi-scan absorption corrections were applied with y-scans [13]. The structures were solved by direct methods using the program SHELXS-97 and were refined by full-matrix least-squares techniques on F2 using anisotropic displacement parameters [14]. The amino hydrogen atoms were located from difference Fourier map and refined isotropically with N-H distances restrained to 0.90(1) A. The remaining hydrogen atoms were placed at the calculated positions. Idealized H atoms were refined with isotropic displacement parameters set to 1.2 (1.5 for methyl groups) times the equivalent isotropic U values of the parent carbon and nitrogen atoms. The crystallographic data for the complexes are listed in Table 1, selected bond lengths and bond angles for I and II are given in Table 2.
A full detail of data collections and structure determinations has been deposited with the Cambridge Crystal-lographic Data Centre (nos. 885818 (I), 885819 (II); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
The Schiff bases HCMP and HDMP were prepared by the condensation of equimolar quantities of 3-bromosalicylaldehyde with N-cyclohexylpropane-1,3-diamine and N,N-dimethylpropane-1,3-di-amine, respectively, in methanol at ambient temperature [10]. The Schiff bases prepared in this way are formed in nearly quantitative yields and are of high purity. The complexes were readily synthesized by reaction of the corresponding Schiff base and metal salt in methanol at ambient temperature. All the compounds 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 the elemental analyses are in accord with the composition suggested for the ligands and the complexes.
768 XUE et al.
Table 1. Crystallographic data and refinement parameters for structures I and II
Parameter Value
I II
Habit, color Block, green Block, colorless
Formula weight 735.2 421.5
Temperature, K 298(2) 298(2)
Crystal size, mm 0.18 x 0.17 x 0.17 0.23 x 0.18 x 0.17
Radiation (Ä,, Â) MoO (0.71073) Mo^a (0.71073)
Crystal system Monoclinic Monoclinic
Space group P2x/c C2/c
Unit cell dimensions:
a, Â 12.0304(6) 22.286(5)
b, Â 13.1594(6) 12.210(3)
c, Â 10.2445(5) 14.513(3)
ß, deg 101.019(1) 124.118(3)
V, Â3 1591.9(1) 3269.5(13)
Z 2 8
Pcalcd g cm-3 1.534 1.712
F(000) 756 1680
Absorption coefficient, mm-1 3.155 4.266
9 Range for data collection, deg 2.5-27.6 2.2-25.0
Index ranges, h, k, l -12 < h < 14; -9 < k < 15; -12 < l < 12 -26 < h < 20; -13 < k < 14; -16 < l < 17
Reflections collected 8294 8294
Independent reflections 2964 3000
Data/parameters 2476/190 2104/177
Final R indices (I> 2a(I)) Ri = 0.0265, wR2 = 0.0608 R1 = 0.0344, wR2 = 0.0714
R indices (all data) R\ = 0.0353, wR2 = 0.0647 R1 = 0.0612, wR2 = 0.0810
Goodness-of-fit on F 2 1.044 1.034
APmaxMPmirn « Â~3 0.349/-0.478 0.430/-0.500
Table 2. Selected bond lengths (A) and bond angles (deg) for compounds for I and II
Bond d, Â Bond d, Â
Ni(1)-O(1) Ni(1)-N(2) Zn(1)-O(1) Zn(1)-Cl(1) 2.0245(13) 2.2527(17) 1.939(3) 2.2502(10) I Ni(1)-N(1) I Zn(1)-N(1) Zn(1)-Cl(2) 2.0500(16) 2.025(3) 2.2101(12)
Angle ro, deg Angle ro, deg
O(1)Ni(1)N(2) N(1)Ni(1)N(2) O(1)Zn(1)N(1) O(1)Zn(1)Cl(1) N(1)Zn(1)Cl(1) 93.63(6) 84.08(6) 95.64(12) 109.99(8) 106.44(8) I O(1)Ni(1)N(1) I O(1)Zn(1)Cl(2) N(1)Zn(1)Cl(2) Cl(2)Zn(1)Cl(1) 87.15(6) 110.63(8) 117.37(9) 115.02(5)
For the IR spectra of both complexes, the strong bands observed at 1625 cm-1 for I and 1626 cm-1 for II are assigned to the azomethine group vibration.
The molecular structure of complex I is shown in Fig. 1a. The complex is a centrosymmetric mononuclear nickel(II) compound. The Ni atom is coordinated by two phenolate O, two imine N, and two amine N atoms from two CMP ligands, forming an octahedral geometry. The Schiff base ligand CMP acts as a tridentate ligand, forming two six-membered chelate rings with the Ni atom. The two axial bonds (Ni(1) -N(2) and Ni(1)—N(2A), symmetry code for A: 1 — x, — y, 2 — z) are much longer than the basal bonds, which is caused by the Jahn—Teller effects. The bond distances subtended at the Ni atom are comparable to those observed in the similar nickel(II) complexes with Schiff bases [15—17].
Table 3. MIC values (p.g/mL) for the ant
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