Zinc(II) complexes with 1,8-naphthyridine-based ligand: Crystal structures and luminescent properties |
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| Authors: | Yong Chen Xin Gan |
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| Institution: | a Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100080, PR China
b College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, PR China |
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| Abstract: | The reactions of 2,4-dimethyl-7-(2-pyridylamino)-1,8-naphthyridine (L1) with Zn(ClO4)2 · 6H2O, and bis(5,7-dimethyl-1,8-naphthyrid-2-yl)amine ligand (L2) with Zn(OAc)2 · 2H2O, ZnCl2 or Zn(ClO4)2 · 6H2O afforded four blue luminescent zinc(II) complexes, Zn(L1)2](ClO4)2 · 2CH2Cl2 (1), Zn(L2)(OAc)2] · CH2Cl2 (2), Zn(L2)2]ZnCl4] · 3.5CH2Cl2 (3) and Zn(L2)2](ClO4)2 (4), respectively. Crystal structures of complexes 1-3 have been determined by X-ray structural analyses as mononuclear complexes with pseudo-tetrahedral geometry. The crystal packing of 1 reveals the coordination cation which is self-assembled to stair chains through aromatic π-π interactions. The intermolecular N-H?O hydrogen bond in 2 generates a centrosymmetric H-bonded dimer. However, the crystal lattice of 3 shows that the molecules are linked by extensive intermolecular hydrogen bonds between the amino groups and the  anions, resulting in a one-dimensional zigzag chain. Furthermore, these molecular pairs or chains were self-assembled to two-dimensional sheets or three-dimensional networks through aromatic π-π interactions. All the zinc(II) complexes display intense intraligand 1(π-π∗) fluorescence with λmax at 380 and 393 nm for 1, 385 and 404 nm for 2-4 in methanol at room temperature, respectively. Emission quantum yields of these complexes are in the range from 0.41 to 0.57. The broad emission bands in their solid-state emission spectra are attributed to intraligand 1(π-π∗) transition and aromatic π-π interactions as well. |
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| Keywords: | Zinc(II) complex Naphthyridine Self-assemble Crystal structures Photoluminescence |
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