научная статья по теме SYNTHESIS AND CRYSTAL STRUCTURES OF COBALT(III) AND ZINC(II) COMPLEXES DERIVED FROM 4-CHLORO-2-[(2-MORPHOLIN-4-YLETHYLIMINO)METHYL]PHENOL WITH UREASE INHIBITORY ACTIVITY Химия

КООРДИНАЦИОННАЯ ХИМИЯ, 2010, том 36, № 3, с. 179-184

УДК 541.49

SYNTHESIS AND CRYSTAL STRUCTURES OF COBALT(III) AND ZINC(II) COMPLEXES DERIVED FROM 4-CHLORO-2-[(2-MORPHOLIN-4-YLETHYLIMINO)METHYL]PHENOL WITH UREASE INHIBITORY ACTIVITY

© 2010 C. Y. Wang

Department of Chemistry, Huzhou University, Huzhou 313000, P.R. China E-mail: chenyi_wang@163.com Received August 6, 2009

A new mononuclear cobalt(III) complex, [CoL2(N3)]2 • CH3OH (I), and a new mononuclear zinc(II) complex, [ZnLCl(CH3OH)] (II) (HL = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. The crystal of I is monoclinic: space group P2x/c, a = 18.742(2), b = 15.197(2), c = 25.646(2) A, в = 125.996(3)°, V = 5909.8(11) A3, Z = 4. The crystal of II is monoclinic: space group P2l/c, a = 7.257(1), b = 24.707(2), c = 9.637(1) A, в = 101.557(2)°, V = 1692.9(3) A3, Z = 4. The Co atom in I is in an octahedral coordination, and the Zn atom in II is in a trigonal-bipyramidal coordination. The urease inhibitory test shows that complex I has strong urease inhibitory activity, while complex II has no activity.

INTRODUCTION

EXPERIMENTAL

Cobalt and zinc complexes with Schiff bases have been attracted much attention in coordination chemistry and bioinorganic chemistry due to their versatile structures and biological properties [1—6]. Ureases are an important class of enzymes involved in the degradative processing of urea [7—9]. They are ubiquitous in nature and directly associated with the formation of infection stones and contribute to the pathogenesis of pyelonephritis, urolithiasis, ammonia encephalopathy, hepatic coma, and urinary catheter encrustation. High concentration of ammonia arising from these reactions, as well as accompanying pH elevation, has important implications in medicine and agriculture [10, 11]. Therefore, urease inhibitors have recently been attracted much attention as potential new anti-ulcer drugs. A recent research indicated that the Schiff base complexes had potent urease inhibitory activity [12]. Schiff bases derived from the condensation of salicylaldehyde and its derivatives with primary amines represent an important class of chelating ligands, the metal complexes of which have been widely studied. However, no complexes with the Schiff base 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phe-nol (HL) have been reported. In this paper, a new mononuclear cobalt(III) complex, [CoL2(N3)]2 • CH3OH (I), and a new mononuclear zinc(II) complex, [ZnLCl(CH3OH)] (II), were prepared and structurally characterized. The urease inhibitory activities of the complexes were determined.

Cl

O

OH

(HL)

Materials and measurements. All chemicals and reagents used for the preparation of the ligands and complexes were commercial products (Lancaster) and used without fUrther purification. Jack bean urease was obtained from Sigma-Aldrich Co. (St. Louis, MO, USA). C, H, and N analyses were performed with a PerkinElmer 2400 series II analyzer. The infrared spectra (KBr pellet) were recorded using a FTS165 Bio-Rad FTIR spectrophotometer in the range 4000—400 cm-1.

Synthesis of HL. A methanolic solution (10 ml) of 2-morpholin-4-ylethylamine (130.2 mg) was added with stirring to a methanolic solution (20 ml) of 5-chlorosali-cylaldehyde (1.0 mmol, 156.6 mg). The mixture was stirred at reflux for 30 min to give a yellow solution. The solution was evaporated to give a yellow powder, which was washed with methanol and dried in air. The yield was 93%.

For C13H17ClN2O2

anal. calcd, %: C, 58.1; H, 6.4; N, 10.4. Found, %: C, 58.5; H, 6.3; N, 10.6.

Synthesis of [CoL2(N3)] • CH3OH (I). A methanolic solution (5 ml) of Co(ClO4)2 • 6H2O (0.1 mmol, 36.6 mg) was added with stirring to a methanolic solution (10 ml) of HL (0.1 mmol, 26.8 mg) and sodium azide (0.1 mmol, 6.5 mg). The mixture was stirred for 30 min at room temperature and filtered. Upon keeping the filtrate in air for a few days, red block-shaped crystals ofl, suitable for X-ray single-crystal diffraction, were formed on the bottom of the vessel. The crystals were collected by filtration, washed

Table 1. Crystallographic parameters and summary of data collection and refinement for the complexes I and II

washed three times with cold methanol, and dried in air. The yield was 62% based on HL.

Parameter Value

I II

M 1304.9 400.6

Crystal shape/color Block/red Block/colorless

Crystal size, mm 0.18 x 0.17 x 0.15 0.23 x 0.20 x 0.20

Crystal system Monoclinic Monoclinic

Space group P2/ P21/c

a, A 18.742(2) 7.257(1)

b, A 15.197(2) 24.707(2)

c, A 25.646(2) 9.637(1)

P, deg 125.996(3) 101.557(2)

V, A3 5909.8(11) 1692.9(3)

Z 4 4

^ mm-1 0.809 1.778

T J min 0.868 0.685

T J max 0.888 0.717

Reflections/parameters 12699/741 3666/203

Independent reflections 6278 3151

F(000) 2712 824

Goodness-of-fit on F2 1.019 1.044

R1, wR2 (I> 2a(I))* 0.0551, 0.1295 0.0298, 0.0749

R1, wR2 (all data)* 0.1347, 0.1849 0.0366, 0.0780

For Ci4H2oCl2N2Ü3Zn

anal. calcd, %: Found, %:

C, 42.0; C, 41.5;

H, 5.0; H, 5.1;

N, 7.0. N, 6.7.

*R1 = Sji^oi - |iC!!/^oi, wR2 = fO - F2)2/2w(F0)2]1/2.

Crystal structure determination. A suitable single crystal of each complex was mounted on a glass fiber. The diffraction experiments were carried out on a Bruker AXS SMART CCD diffractometer. The program SMART was used for collecting frames of data, indexing reflections, and determination oflattice parameters [13]. SAINT was used for integration ofthe intensity ofreflections and scaling [13], SADABS was used for absorption correction [14], and SHELXTL was applied for space group and structure determination and least-squares refinements on F2 [15]. All non-hydrogen atoms were refined anisotropi-cally. The H(3^) atom attached to O(3) in II was located from a difference Fourier map and refined isotropically with O—H distance restrained to 0.85(1) A. Other hydrogen atoms were placed in idealized positions and allowed to ride on the connecting atoms. The crystallographic data for the complexes are summarized in Table 1. Selected bond lengths and angles are listed in Table 2. Hydrogen bonds are listed in Table 3.

Atomic coordinates and other structural parameters of the complexes have been deposited with the Cambridge Crystallographic Data Center (nos. 740909 (I) and 740910 (II); deposit@ccdc.cam.ac.uk).

Measurement of urease. The assay mixture containing 25 |l ofjack bean urease and 25 |l (100 |g) ofthe test compound was preincubated for 0.5 or 3 h at room temperature in a 96-well assay plate. After preincubation, 0.2 ml of 100 mM phosphate buffer (pH 6.8) containing 500 mM urea and 0.002% phenol red were added and incubated at room temperature. The reaction time was measured by a microplate reader (570 nm), which was required for enough ammonium carbonate to form to raise the pH of a phosphate buffer from 6.8 to 7.7 [16].

three times with cold methanol, and dried in air. The yield was 37% based on HL.

For C53H68CI4C02N14O9

anal. calcd, %: Found, %:

C, 48.8; C, 48.3;

H, 5.3; H, 5.5;

N, 15.0. N, 15.3.

Synthesis of [ZnLCl(CH3OH)] (II). A methanolic solution (10 ml) of HL (0.1 mmol, 26.8 mg) was added with stirring to a methanolic solution (5 ml) ofZnCl2 (0.1 mmol, 13.6 mg). The mixture was stirred for 30 min at room temperature and filtered. Upon keeping the filtrate in air for a few days, colorless block-shaped crystals of II, suitable for X-ray single-crystal diffraction, were formed on the bottom of the vessel. The crystals were collected by filtration,

RESULTS AND DISCUSSION

The Schiff base HL was readily synthesized via Schiff base condensation using equimolar quantities of 5-chlo-rosalicylaldehyde with 2-morpholin-4-ylethylamine. Complex I was synthesized by mixing equimolar quantities of HL, NaN3, and Co(ClO4)2 • 6H2O in a methanolic solution, yielding an azide-coordinated octahedral co-balt(III) complex. It is notable that the Co atom was oxidized during the process. Complex II was synthesized by a similar procedure as that described for I, but with Co(ClO4)2 • 6H2O replaced by ZnCl2, yielding a chloride-coordinated trigonal bipyramidal zinc(II) complex.

The Schiff base HL is soluble in DMF, DMSO, methanol, ethanol, chloroform, and acetonitrile. The elemental analyses are in good agreement with the chemical formula proposed for the compound. Both complexes are

SYNTHESIS AND CRYSTAL STRUCTURES OF COBALT(ni) AND ZINC(II)

181

Table 2. Selected bond lengths and bond angles for the complexes

Bond

d, A

Bond

d, A

Co(1)- O(1) 1.894(3) Co(1)- O(3) 1.880(3)

Co(1)- -N(1) 1.958(4) Co(1)- N(3) 1.901(4)

Co(1)- -N(4) 2.074(4) Co(1)- N(5) 1.927(4)

Co(2)- O(5) 1.910(3) Co(2)- O(7) 1.888(3)

Co(2)- -N(8) 1.953(4) Co(2)- -N(10) 1.895(4)

Co(2)- -N(11) 2.067(4) Co(2)- N(12) 1.927(4)

II

Zn(1)-O(1) Zn(1)-N(1) Zn(1)-Cl(2) 2.070(2) 2.017(2) 2.219(1) Zn(1)-O(3) Zn(1)-N(2) 2.026(2) 2.515(2)

Angle ю, deg Angle ю, deg

N(1)Zn(1)O(3) O(3)Zn(1)O(1) O(3)Zn(1)Cl(2) N(1)Zn(1)N(2) O(1)Zn(1)N(2) I 114.3(1) 89.7(1) 114.6(1) 76.9(1) 165.7(1) N(1)Zn(1)O(1) N(1)Zn(1)Cl(2) O(1)Zn(1)Cl(2) O(3)Zn(1)N(2) Cl(2)Zn(1)N(2) 89.4(1) 130.3(1) 98.5(1) 92.1(1) 93.6(1)

II

O(3)Co(1)O(1) 90.0(2) O(3)Co(1)N(3) 94.4(2

O(1)Co(1)N(3) 85.7(2) O(3)Co(1)N(5) 91.0(2

O(1)Co(1)N(5) 172.4(2) N(3)Co(1)N(5) 86.7(2

O(3)Co(1)N(1) 86.2(2) O(1)Co(1)N(1) 94.7(2

N(3)Co(1)N(1) 179.3(2) N(5)Co(1)N(1) 92.9(2

O(3)Co(1)N(4) 178.6(2) O(1)Co(1)N(4) 88.6(2

N(3)Co(1)N(4) 85.4(2) N(5)Co(1)N(4) 90.4(2

N(1)Co(1)N(4) 94.0(2) O(7)Co(2)N(10) 93.2(2

O(7)Co(2)O(5) 89.8(2) N(10)Co(2)O(5) 84.7(2

O(7)Co(2)N(12) 92.8(2) N(10)Co(2)N(12) 88.5(2

O(5)Co(2)N(12) 172.8(2) O(7)Co(2)N(8) 85.6(2

N(10)Co(2)N(8) 178.6(2) O(5)Co(2)N(8) 94.4(2

N(12)Co(2)N(8) 92.4(2) O(7)Co(2)N(11) 179.0(2

N(10)Co(2)N(11) 86.3(2) O(5)Co(2)N(11) 90.9(2

N(12)Co(2)N(11) 86.3(2) N(8)Co(2)N(11) 94.9(2

stable in air at room temperature. They are soluble in DMF, DMSO, methanol, ethanol, and a

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