Two unprecedented NLO-active coordination polymers constructed by a semi-rigid tetrahedral linker

The assemblies of tetrahedral linker tetrakis[4-(carboxyphenyl)oxamethyl]methane acid (H(4)L) with ZnCl(2) and CdBr(2) yield two noncentrosymmetric, NLO-active coordination polymers [Zn(4)(L(2))(H(2)O)(3)(DMA)].2H(2)O (1) and [Cd(2)L(DMA)(2)(H(2)O)(2)] (2), respectively. 1 has an unprecedented 2-fold interpenetrating sxa topology with ferroelectric properties, while 2 has a 7-fold interpenetrating dia network.