Fluorescent Properties of three Zinc(II) Coordination Polymers derived from Flexible N ‐(4/3‐Carboxyphenyl)iminodiacetic Acids

Three polymers [Zn 2 ( p ‐CPIDA)(OH)] n ( 1 ), [Zn 2 ( p ‐HCPIDA) 2 (bipy)(H 2 O) 4 ] · 2H 2 O ( 2 ), and [Zn( m ‐HCPIDA)(bipy)] n ( 3 ) [ p / m ‐H 3 CPIDA = N ‐(4/3‐carboxyphenyl) iminodiacetic acid, bipy = 4, 4′‐bipyridine] were hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, X‐ray powder diffraction patterns (XPRD), FTIR spectroscopy, and fluorescence analyses. Compound 1 displays an interesting three‐dimensional framework consisting of novel paddle wheel Zn 8 O 10 C 2 units, which are further linked by p ‐CPIDA 3– ligands with versatile coordination modes. In 2 , the structural motifs formed by terminal p ‐HCPIDA 2– ligands and Zn II ions are bridged by ancillary bipy to give a zero‐dimensional Z‐shaped dimer. Compound 3 has an infinite zigzag chain linked by bipy, in which terminal m ‐HCPIDA 2– ligands alternately run along the chain like flags. Compounds 2 and 3 are further connected by hydrogen bonding and π ··· π stacking interactions to result in 3D supramolecular frameworks. Moreover, compounds 1 – 3 exhibit intense solid state fluorescent emissions at room temperature.