Visible Light-induced Photoluminescence of a Zinc(Ⅱ)Complex of N-methyl-4,4-bipyridinium Cation

摘要

Compounds with visible-light-induced photoluminescence are particularly attractive in acting as the emitting components of light-emitting diodes and fluorescent probes for biological applications.A new complex [Zn(NCS)3(MQ)] (MQ+ =N-methyl-4,4'-bipyridinium) with an isolated molecular structure has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction,elemental analysis,IR spectroscopy and solid-state photoluminescent determination.Crystal data:C14H11NsS3Zn,Mr =410.83,monoclinic,space group P21/c,a =8.809(5),b =13.138(7),c =15.580(9) (A),β=104.433(10)°,V =1746.2(17) (A)3,Z =4,Dc =1.563 g.cm-3,μ =1.769 mm-1,F(000) =832,the final R =0.0376 and wR =0.1243 for 2850 observed reflections with I ＞ 2σ(I).In the crystal structure,the zinc atom is tetrahedrally coordinated by one MQ+ ligand and three NCS-groups to yield a tetrahedral configuration.The bond length of Zn-NMQ is clearly shorter than those found in reported Zn(Ⅱ) complexes of 4,4'-bipy.The isolated units are joined by C-H…S interactions to generate a 2D hydrogen-bonding network.This compound displays visible light-induced photoluminescence,which originates from both intraligand charge-transfer of the MQ+ligand and NCS-→ MQ+ charge-transfer according to a density of states (DOS) calculation.Moreover,its emission band shows a clear blue shift compared with those of halide compounds.