Two zinc coordination polymers with photochromic behaviors and photo-controlled luminescence properties

Abstract

Two new coordination polymers, [Zn(3-NDI)_0.5(NDC)(DMF)]_n (1) and {[Zn_1.5(3-NDI)_0.5(BDC)_1.5]·2.5DMF}_n (2), were synthesized based on naphthalenediimide and aromatic dicarboxylic acids (3-NDI = N,N′-bis (3-pyridine methyl)-1,4,5,8-naphthalenediimide, H₂NDC = 1,4-naphthalenedicarboxylic acid, H₂BDC = terephthalic acid, and DMF = N,N′-dimethylformamide). Complex 1 is a two-dimensional structure, whereas complex 2 is a three-dimensional structure with a hex topology. Both complexes feature photochromic behaviors, which are proved by single-crystal X-ray diffraction, UV-vis spectroscopy and EPR characterization. Furthermore, both complexes have obvious fluorescence quenching behaviors upon irradiation by using a xenon lamp.