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SYNTHESES, STRUCTURE, AND LUMINESCENCE OF TWO NEW 1D Cd(II) COMPLEXES
© 2015 Y. Wu1, 2 *, J. Wang1, 2, W. P. Wu1, 2, B. Xie2, and X. L. Zhang1, 2
1College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science & Engineering, Zigong, 643000 P.R. China 2Institute of Functional Materials, Sichuan University of Science & Engineering, Zigong, 643000 P.R. China
*E-mail: wuyuhlj@163.com Received January 20, 2015
Two Cd-based complexes with chemical formulae {[Cd(L)(2,2'-Bipy)] • 0.5H20}n (I) and [Cd(L)(3-Mp)2]n (II) (H2L = 3,5-dibromosalicylaldehyde salicylhydrazone; 2,2'-Bipy = 2,2'-pyridine, 3-Mp = 3-methylpyri-dine), have been synthesized and structurally characterized by X-ray single-crystal diffraction (CIF files CCDC nos. 1044341 (I), 1044342 (II)). Furthermore, the luminescence properties of compounds I and II have been investigated.
DOI: 10.7868/S0132344X15080083
INTRODUCTION
Hydrazone complexes are of interest for their various applications in analytical chemistry, catalysis, nonlinear optical materials and biochemistry. In a variety of synthetic fluorescent chemosensors, acylhy-drazone Schiff base [1—6], which contains the group —CONHN=CH—, have been proved to be good fluorescent receptor. The formation of complexes with a coplanar structure is conducive to the production of fluorescence: the reaction of a metal ion with a chelating agent induces rigidity in the resulting molecule and tends to produce fluorescence [7, 8]. From the viewpoint of structure, the ligands with the necessary NNS coordination sites can play an important role in assembling different coordination structures and even interesting supramolecular frameworks [9—13]. Our strategy is to explore the linking of multidentate hydrazone ligand with aromatic systems in cadmium coordination chemistry, and investigate the effect of chelating N-donor ligands on the resulting motifs. In this paper, 3,5-dibromosalicylaldehyde salicylhydrazone (H2L), which acts as a good fluorescent and colorimetric detector for d10 Cd(II) system. We choose the L as the flu-orophore base on the fact that it possesses desirable pho-tophysical properties, such as a large Stocks Shift, visible excitation and emission wavelength. Herein, we report two complexes {[Cd(L)(2,2'-Bipy)] • 0.5H2O}„ (I) and [Cd(L)(3-Mp)2]„ (II), where 2,2'-Bipy = 2,2'-pyri-dine, 3-Mp = 3-methylpyridine, Their structures have been characterized by X-ray single-crystal diffraction, FTIR and elemental analysis. The thermal and luminescence of properties were also investigated of complexes I and II.
EXPERIMENTAL
Materials and method. All reagents were purchased from commercial sources and used as received. IR spectra were recorded with a PerkinElmer Spectrum One spectrometer in the region 4000—400 cm-1 using KBr pellets. TGA was carried out with a Metter-Toledo TA 50 in dry dinitrogen (60 mL min-1) at a heating rate of 5°C min-1. X-ray powder diffraction (PXRD) data were recorded on a Rigaku RU200 diffractometer at 60 kV, 300 mA for CuKa radiation (X = 1.5406 A) with a scan speed of 2°C/min and a step size of 0.013° in 29.
X-ray crystallography. Single crystal X-ray diffraction analysis of compounds I and II was carried out on a Bruker SMART APEX II CCD diffractometer equipped with a graphite monochromated MoKa radiation (X = 0.71073 A) by using scan technique at room temperature. Data were processed using the Bruker SAINT package and the structures solution and the refinement procedure was performed using SHELX-97 [14]. The structure was solved by direct methods and refined by full-matrix least-squares fitting on F2. The hydrogen atoms of organic ligands were placed in calculated positions and refined using a riding on attached atoms with isotropic thermal parameters 1.2 times those of their carrier atoms. The hydrogen atoms of lattice water molecule in compound I were not located using the different Fourier method. Crystallographic data of I and II are given in Table 1. Selected bond distances and bond angles are listed in Table 2.
Supplementary material for structures I and II has been deposited with the Cambridge Crystallographic Data Centre (nos. CCDC 1044341 (I), 1044342 (II); de-posit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
SYNTHESES, STRUCTURE, AND LUMINESCENCE Table 1. Crystallographic data and structural refinement details of complexes I and II
Parameter Value
I II
Formula weight 1379.27 710.70
Crystal system Monoclinic Monoclinic
Space group P2i/c P21/C1
Crystal color Yellow Yellow
a, A 12.359(7) 9.164(5)
b, A 9.262(5) 24.512(13)
c, A 22.460(11) 13.395(6)
P 100.290(9) 116.05(3)
V, A3 2530(2) 2703(2)
Z 2 4
P calcd g/cm3 1.811 1.746
p., mm-1 4.057 3.798
F(000) 1340 1392
9 Range, deg 2.38-25.43 2.32-22.78
Index ranges hkl -14 < h < 14, -10 < k < 11, -27 < l< 23 -11 < h < 10, -29 < k < 28, -9 < l < 16
Reflection collected 12806 13956
Independent reflections (Rint) 0.0452 0.0529
Reflections with I > 2a(I) 4592 4903
Number of parameters 308 327
GOOF 1.161 0.815
R1, wR2 (I> 2ct(I))* 0.0495, 0.1494 0.0386, 0.1007
R1, wR2 (all data)** 0.0721, 0.1635 0.0779, 0.1283
APma« APmin e A.-3 1.773, -1.050 0.455, -0.699
R = S(F0 - FC)/S(F0), ** wRj = {S[w(F0 - Fc )2]/S(F0 )2}1/2.
Synthesis of complex I. A DMF solution (15 mL) of
the Schiff base (1 mmol) and 2,2'-Bipy (1.5 mmol) were added with stirring to a DMF solution (15 mL) of Cd(Ac)2 (1 mmol). After adding two drops of triethy-lamine, the reaction solution were stirred at room temperature for 2 h. X-ray quality single crystals were formed by slow evaporation of the solutions in air after a few days.
For C48H34N8O7Br4Cd2 (M = 1379.27)
anal. calcd., %: C, 41.80; H, 2.48; N, 8.12.
Found, %: C, 41.39; H, 2.37; N, 8.44.
IR (KBr; v, cm-1): 3421 v.s, 2842 m, 1682 v, 1609 m, 1440 v.s, 1142 v, 1012 m, 759 v.s, 697 v.s, 562 m.
КООРДИНАЦИОННАЯ ХИМИЯ том 41 № 8 2015
Synthesis of complex II was carried out by the same synthetic method used for the preparation of I except that 2,2'-Bipy was replaced by 3-Mp (1.5 mmol).
For C26H22N4O3Br2Cd (M = 710.70)
anal. calcd., %: C, 43.94; H, 3.12; N, 7.88.
Found, %: C, 43.56; H, 3.10; N, 7.59.
IR (KBr; v, cm-1): 3043 m, 2881 v, 1609 m, 1485 v.s, 1424 m, 1333 m, 1131 m, 759 m, 703 v.s, 578 v.
RESULTS AND DISCUSSION
The results of crystallographic analysis revealed that the asymmetric unit of complex I contains one
3*
484 WU et al.
Table 2. Selected bond distances (A) and angles (deg) of structure I and II
Bond d, Â Bond d, Â
Cd(1)-O(3) Cd(1)—N(1) Cd(1)—N(2) Cd(1)-O(1) Cd(1)—O(2) Cd(1)—N(4) 2.198(5) 2.306(5) 2.346(6) I 2.190(4) 2.328(4) 2.366(4) Cd(1)-O(1) Cd(1)—N(3) Cd(1)—O(2) I Cd(1)-O(3) Cd(1)—N(1) Cd(1)—N(3) 2.216(4) 2.307(5) 2.349(5) 2.201(4) 2.348(5) 2.370(5)
Angle ro, deg Angle ro, deg
O(3)Cd(1)O(1) O(1)Cd(1)N(1) O(1)Cd(1)N(3) O(3)Cd(1)N(2) N(1)Cd(1)N(2) O(3)Cd(1)O(2) 104.63(18) 100.07(18) 78.37(17) 157.57(18) 70.1(2) 85.44(17) O(3)Cd(1)N(1) O(3)Cd(1)N(3) N(1)Cd(1)N(3) O(1)Cd(1)N(2) N(3)Cd(1)N(2) O(1)Cd(1)O(2) 91.48(19) 105.77(18) 162.6(2) 91.5(2) 92.55(19) 148.11(17)
II
O(1)Cd(1)O(3) 119.97(14) O(1)Cd(1)O(2) 147.80(14)
O(3)Cd(1)O(2) 91.36(13) O(1)Cd(1)N(1) 78.50(14)
O(3)Cd(1)N(1) 161.27(14) O(2)Cd(1)N(1) 69.93(13)
O(1)Cd(1)N(4) 90.13(16) O(3)Cd(1)N(4) 86.12(16)
O(2)Cd(1)N(4) 84.37(15) N(1)Cd(1)N(4) 91.01(16)
O(1)Cd(1)N(3) 95.18(18) O(3)Cd(1)N(3) 89.96(16)
O(2)Cd(1)N(3) 91.87(17) N(4)Cd(1)N(3) 174.49(18)
Cd(II) atom, one L ligand, one 2,2'-Bipy ligand and half lattice water molecule (Fig. 1a). The Cd2+ ion in compound I is surrounded by two phenol oxygen atom, a salicyloyl oxygen atom and a hydrazine nitrogen atom from one L ligand, and two nitrogen atoms from one chelating 2,2'-Bipy ligand, forming a distorted CdN3O3 octahedral configuration. In the equatorial plane, one N(2) (2,2'-Bipy) atom and one O(2) (Acyl) atom, and two hydroxyl oxygen atoms of O(1) and O(3) are coordinated to the Cd center in trans arrangement. The Cd(II)—N/O distances are 2.346(6) and 2.349(5) Â, respectively. The axial positions are occupied by two N atoms (N(1) and N(3)) with the large distance of 2.307(5) Â to the Cd center. Hence, the octahedron is obviously elongated in the axial direction due to Jahn—Tellar distortion. In addition, the
carbonyl-O of the L ligand enolizes during complexation and deprotonates to bond through carbonylate-O. So, phenolate-O bridges between adjacent metal atoms result into a 1D chain structure in I (Fig. 2a).
The results of crystallographic analysis revealed that the asymmetric unit of complex II contains one Cd(II) atom, one L ligand, two 3-Mp ligands (Fig. 1b). The Cd2+ ion is coordinated to one bi-anionic ligand through a carbonyl-O, azomethine-N and two pheno-late-O of a L ligand, and two N atoms from two 3-Mp ligands. The molecular structure shows a distorted octahedral geometry around metal ion.
The Cd—O(2) (carbonyl-O), Cd-O(3)/Cd-O(1) (phenolate-O), Cd-N(1) (azomethine-N) bond lengths are 2.328(4), 2.201(4), 2.190(4) and 2.348(5) Â,
respectively [15]. The bond distances of Cd-N(3)/Cd-N(4) are 2.370(5), 2.366(4) A, respectively. These bond lengths fall in the normal range of many octahedral Cd(II) complexes with N,O-donor ligands. The shorter Cd-O(3) bond length as compared to Cd-O(2) indicates that the phenolate-O bond is more stronger than the carbonyl oxygen [16]. The observed bond angles of O(2)Cd(1)O(1), 147.80(14)°, N(1)Cd(1)O(1), 78.50(14)°, N(3)Cd(1)N(4) 174.49(18)° indicate that the octahedral geometry is slightly distorted due to chelation effect [17]. The phenolate-O bridges between adjacent metal atoms also result into a 1D chain structure in II (Fig. 2b).
In the FTIR spectra, v(N-H) observed at 3249 cm-1 in the IR spectrum of free ligand [18], occurs nearly at the same or at a slightly shifted position in the Cd(II)-based complexes, indicating the non-involvement of NH group in bonding. The v(C=O) band observed at 1638 cm-1 in
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