Synthesis And Crystal Structure Of Metal Coordination Polymers 2-carboxyethyl Phenylphosphinic Acid And 4,4'-bipyridine Ligand Based

Metal phosphonates have received much attention in inorganic chemistry. Recently, we haveundertaken research work on the coordination and supramolecular chemistry of an asymmetricbifunctional ligand,（2-carboxyethyl）（phenyl）phosphinic acid. Such ligand features two formallyanalogous carboxylate and phosphinate moieties （i.e., both feature two potentinal O donors）separated by a flexible CH2CH2spacer, with the latter being further bonded to a phenyl group.thus lead to the formation of new structural types.In this work, we choose2-carboxyethyl)（phenyl）phosphinate （L2-） and4,4’-bipyridine （bipy）as ligands. Five novel metal phosphinates based on such ligands were obtained, which werefurther characterized by single crystal X-ray diffraction, powder X-ray diffraction, IRspectroscopy, thermogravimetric analysis, and fluorescence analysis.The five metal phosphinates are as follows:[Cd（L）（bipy）（H₂O）₂]（1）；[Cd（L）（bipy）]（2）；[Cd（L）（bipy）_0.5]·0.5H₂O （3）；[CO（L）（bipy）（H₂O）]·H₂O （4）；[Cu（L）（bipy）（H₂O）]（5）Among them,1can be converted to two new2D/3D varieties under hydrothermal treatmentsat different temperatures, namely,2and3, respectively. Compounds4and5both exhibittwo-dimensional netwok.The different structures in them are mainly due to the various coordination modes of the2-carboxyethyl)（phenyl）phosphinate ligand.