УДК 541.49
SYNTHESES, CRYSTAL STRUCTURES, AND FLUORESCENCE PROPERTIES OF ZINC(II) COMPLEXES WITH MULTI-DENTATE SCHIFF BASES
© 2013 S. S. Qian1, X. S. Cheng2, J. Q. Ren2, Z. L. You2, *, and H. L. Zhu1, *
1School of Life Sciences, Shandong University of Technology, ZiBo, 255049 P.R. China 2Department of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029 P.R. China
*E-mail: hailiang_zhu@163.com Received February 14, 2012
Two new structurally similar mononuclear Schiff base zinc(II) complexes, [ZnBr(ClMP)] (I) and [ZnCl(NMP)] (II) (ClMP = 4-chloro-2-[(3-morpholin-4-ylpropylimino)methyl]phenolate; NMP = 4-ni-tro-2-[(3-morpholin-4-ylpropylimino)methyl]phenolate), and two new dinuclear Schiff base zinc(II) complexes, [Zn2(EMP)2I2] (III), and [Zn2(MPA)(CH3OH)2(N3)2] (IV) (EMP = 5-diethylamino-2-[(2-dimeth-ylaminoethylimino)methyl]phenolate; MPA = N,N'-bis(3-methoxysalicylidene)propane-1,3-diamine), have been prepared and characterized mainly by single-cyrstal X-ray diffraction. Complex I crystallizes in the mono-clinic space group P21/n with unit cell dimensions: a = 15.116(3), b = 9.465(1), c = 23.714(4) Â, в = 104.358(2)°,
V = 3286.9(8) Â3, Z = 8, R1 = 0.0439, and wR2 = 0.0736. Complex II crystallizes in the monoclinic space group P21/c with unit cell dimensions: a = 7.253(2), b = 16.652(4), c = 13.568(3) Â, в = 96.600(2)°, V = = 1627.8(6) Â3, Z = 4, Ri = 0.0417, and wR2 = 0.0809. Complex III crystallizes in the monoclinic space group C2/c with unit cell dimensions: a = 27.962(2), b = 8.246(2), c = 31.605(3) Â, в = 90.343(2)°, V = 7287.4(15) Â3, Z = 8, R1 = 0.0721, and wR2 = 0.1709. Complex IV crystallizes in the monoclinic space group C2/c with unit
cell dimensions: a = 20.483(3), b = 11.344(2), c = 14.909(3) Â, в = 131.650(1)°, V = 2588.6(7) Â3, Z = 4, R1 = 0.0343, and wR2 = 0.0792. Each Zn atom in I and II are four-coordinated in a tetrahedral geometry by the NNO donor set of the Schiff base ligand and one halide atom. The Zn atoms in III are in square pyramidal coordination, and those in IV are in octahedral and tetrahedral coordination. Thermal stability and fluorescence properties of the complexes I and II have also been determined.
DOI: 10.7868/S0132344X1311008X
INTRODUCTION
Schiff base complexes have been received considerable attention for their importance in the fields of coordination chemistry related to catalysis and enzymatic reactions, magnetism and molecular architectures [1—5]. Zinc is an important element in biological systems, functions as the active site of hydrolytic enzymes, such as carboxypeptidase and carbonic anhy-drase where it is in a hard-donor coordination environment of nitrogen and oxygen atoms [6]. Schiff base zinc complexes have been proved to possess interesting fluorescence properties [7—10]. As a continuation of
our work on the Schiffbase complexes [11—13], we report in this paper the syntheses, crystal structures, thermal stability, and fluorescene properties of four new Schiff base zinc(II) complexes, [ZnBr(ClMP)] (I), [ZnCl(NMP)] (II), [Zn2(EMP)2I2] (III), and [Zn2(MPA)(CH3OH)2(N3)2] (IV) (ClMP = 4-chlo-ro-2-[(3-morpholin-4-ylpropylimino)methyl]phenola-te, NMP = 4-nitro-2-[(3-morpholin-4-ylpropylimi-no)methyl]phenolate, EMP = 5-diethylamino-2-[(2-di-methylaminoethylimino)methyl]phenolate, MPA=N,N'-èis(3-methoxysalicylidene)propane-1,3-diamine)
Cl
OH
HClMP
O
o2n
OH
HNMP
O
N OH HEMP
-N
O
O.
730
h2mpa
EXPERIMENTAL
Materials and measurements. Commercially available 5-chlorosalicylaldehyde, 5-nitrosalicylaldehyde, 4-diethylaminosalicylaldehyde, 3-methoxysalicylal-dehyde, N,N-dimethylethane-1,2-diamine, propane-1,3-diamine, and 3-morpholin-4-ylpropylamine were purchased from Aldrich and used without further purification. Other solvents and reagents were made in China and used as received. The Schiff base H2MPA was prepared according to the literature procedure [14]. C, H and N elemental analyses were performed with a PerkinElmer elemental analyser. Thermal stability analysis was performed on a PerkinElmer Pyris Diamond TG-DTA thermal analyses system. Fluorescence spectra were recorded with an F-2500 FL Spec-trophotometer analyzer.
Synthesis of the Schiff base HClMP. 5-Chlorosali-cylaldehyde (1.0 mmol, 0.156 g) and 3-morpholin-4-ylpropylamine (1.0 mmol, 0.144 g) were dissolved in EtOH (20 mL) with stirring. The mixture was stirred for about 30 min at room temperature to give a yellow solution. The solvent was evaporated to give yellow gummy product of HClMP.
For C14H19N2O2Cl
anal. calcd., %: C, 59.5; H, 6.8; N, 9.9. Found, %: C, 59.4; H, 6.7; N, 10.0.
Synthesis of the Schiff base HMP. 5-Nitrosalicyl-aldehyde (1.0 mmol, 0.167 g) and 3-morpholin-4-yl-propylamine (1.0 mmol, 0.144 g) were dissolved in EtOH (20 mL) with stirring. The mixture was stirred for about 30 min at room temperature to give a yellow solution. The solvent was evaporated to give yellow gummy product of HNMP.
For C14H19N3O4
anal. calcd., %: C, 57.3; H, 6.5; N, 14.3. Found, %: C, 57.1; H, 6.6; N, 14.5.
Synthesis of the Schiff base HEMP. 4-Diethylami-nosalicylaldehyde (1.0 mmol, 0.193 g) and N,N-di-methylethane-1,2-diamine (1.0 mmol, 0.088 g) were dissolved in EtOH (20 mL) with stirring. The mixture was stirred for about 30 min at room temperature to give an orange solution. The solvent was evaporated to give orange gummy product of HEMP.
For C15H25N3O
anal. calcd., %: C, 68.4; H, 9.6; N, 16.0. Found, %: C, 68.3; H, 9.6; N, 15.8.
Synthesis of I. A MeOH solution (5 mL) of ZnBr2 (0.1 mmol, 22.5 mg) was added to a MeOH solution (10 mL) of HClMP (0.1 mmol, 28.2 mg) with stirring. The mixture was stirred for 30 min to give a clear colourless solution. The resulting solution was allowed to
stand in air for a few days. Colourless block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with cold EtOH, and dried in a vacuum over anhydrous CaCl2. The yield was 15.5 mg (36% on the basis of HClMP).
For C14H18N2O2ClBrZn
anal. calcd., %: Found, %:
C, 39.4; C, 39.2;
H, 4.2; H, 4.3;
N, 6.6. N, 6.5.
Synthesis of II. A MeOH solution (5 mL) of ZnCl2 (0.1 mmol, 13.6 mg) was added to a MeOH solution (10 mL) of HNMP (0.1 mmol, 29.3 mg) with stirring. The mixture was stirred for 30 min to give a clear colourless solution. The resulting solution was allowed to stand in air for a few days. Colourless block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with cold EtOH, and dried in a vacuum over anhydrous CaCl2. The yield was 17.0 mg (43% on the basis of HNMP).
For C14H18N3O4ClZn
anal. calcd., %: C, 42.8; H, 4.6; N, 10.7. Found, %: C, 42.6; H, 4.6; N, 10.5.
Synthesis of III. A MeOH solution (5 mL) of ZnI2 (0.2 mmol, 62.0 mg) was added to a MeOH solution (10 mL) of HEMP (0.1 mmol, 26.3 mg) with stirring. The mixture was stirred for 30 min to give a clear light yellow solution. The resulting solution was allowed to stand in air for a few days. Light yellow block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with cold EtOH, and dried in a vacuum over anhydrous CaCl2. The yield was 41.0 mg (45% on the basis of HEMP).
For C30H47N6O2I2Zn2
anal. calcd., %: C, 39.7; H, 5.2; N, 9.3. Found, %: C, 39.5; H, 5.3; N, 9.2.
Synthesis of IV. A MeOH solution (5 mL) of Zn(NO3)2 • 6H2O (0.2 mmol, 54.3 mg) was added to the mixture of a MeOH solution (10 mL) of H2MPA (0.1 mmol, 34.2 mg) and sodium azide (0.2 mmol, 13.0 mg) with stirring. The mixture was stirred for 30 min to give a clear colourless solution. The resulting solution was allowed to stand in air for a few days. Colourless block-shaped crystals suitable for X-ray single crystal analysis were formed at the bottom of the vessel. The isolated product was washed three times with
Table 1. Crystallographic and experimental data for the complexes I—IV
Parameter Value
I II III IV
Fw 427.0 393.1 908.3 619.2
Crystal shape/color Block/colourless Block/colourless Block/colourless Block/colourless
Crystal system Monoclinic Monoclinic Monoclinic Monoclinic
Space group P21/n P21/c C2/c C2/c
a, A 15.116(3) 7.253(2) 27.962(2) 20.483(3)
b, A 9.465(1) 16.652(4) 8.246(2) 11.344(2)
c, A 23.714(4) 13.568(3) 31.605(3) 14.909(3)
P, deg 104.358(2) 96.600(2) 90.343(2) 131.650(1)
V, A3 3286.9(8) 1627.8(6) 7287.4(15) 2588.6(7)
Z 8 4 8 4
T, K 298(2) 298(2) 298(2) 298(2)
^(MoJa), mm-1 4.092 1.695 3.045 1.905
P calcd g cm-3 1.726 1.604 1.656 1.589
F(000) 1712 808 3608 1272
Crystal size, mm 0.17 x 0.15 x 0.15 0.27 x 0.23 x 0.23 0.27 x 0.23 x 0.23 0.28 x 0.27 x 0.23
T J min 0.5430 0.6575 0.4936 0.6175
T J max 0.5788 0.6965 0.5410 0.6684
Reflections collected 7005 3556 7919 2958
Observed reflections (I > 2ct(i)) 3627 2479 5377 2039
Parameters 379 208 387 188
Restraints 0 0 0 8
Goodness of fit on F 2 0.952 1.007 1.095 1.022
R1, wR2 (I> 2ct(i))* 0.0439, 0.0736 0.0417, 0.0809 0.0721, 0.1709 0.0343, 0.0792
R1, wR2 (all data)* 0.1207, 0.0923 0.0747, 0.0911 0.1077, 0.1916 0.0599, 0.0899
* Ri = ZilFoi - !^c!!/E|/oi, wR2 = [Ew(/o2 - F2)2/Ew(Fo2)2]^2.
cold EtOH and dried in a vacuum over anhydrous CaCl2. The yield was 33.5 mg (54% on the basis of HMPA).
For C2iH28NsO6Zn2
anal. calcd., %: C, 40.7; H, 4.6; N, 18.1. Found, %: C, 40.8; H, 4.5; N, 18.0.
X-ray structure determination. Diffraction intensities for the complexes I-IV were collected at 298(2) K using a Bruker SMART 1K area-detector with Mo^a radiation (X = 0.71073 Â). The collected data were reduced using the SAINT program [15], and multi-scan
absorption corrections were performed using the SADABS program [16]. The structures were solved by direct methods and refined against F2 by full-matrix least-squares methods using the SHELXTL version 5.1 [17]. All of the non-hydrogen atoms were refined
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