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

The reaction of CdCl 2 · 2.5H 2 O with 1,1′‐bis(3‐carboxybenzyl)‐4,4′‐bipyridinium dichloride (H 2 L1 · Cl 2 ) or 4,4′‐bis[(3‐carboxypyridino)methyl]‐biphenyl dichloride (H 2 L2 · Cl 2 ) in a dimethylformamide/methanol mixed‐solvent system at room temperature, affording the complexes [(CdCl 2 ) 3 (L1) 3 ] n ( 1 ) and {[CdCl 2 (L2)(H 2 O) 2 ] · 2H 2 O} 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 H 2 L1 · Cl 2 and H 2 L2 · Cl 2 ligands.