The Impact of Charge-Distribution on Photochromic Properties in 1D Coordination Polymers.

The reaction of CdCl2·2.5H2O with 1,1'-bis(3-carboxybenzyl)-4,4'-bipyridinium dichloride (H2L1·Cl2) or 4,4'-bis[(3-carboxypyridino)methyl]-biphenyl dichloride (H2L2·Cl2) in a dimethylformamide/methanol mixed-solvent system at room temperature, affording the complexes [(CdCl2)3(L1)3]n (1) and {[CdCl2(L2)(H2O)2]· 2H2O}n (2). They were characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. Both 1 and 2 exhibit 1D coordination networks, which further stack into a 3D supramolecular structure by hydrogen bonding and π-π interactions. Furthermore, these two complexes exhibit different photochromic behavior in the solid state, which may originate from different charge-distributions of H2L1·Cl2 and H2L2·Cl2 ligands. [ABSTRACT FROM AUTHOR]