Synthesis, Structures, and Sorption Properties of Two New Metal–Organic Frameworks Constructed by the Polycarboxylate Ligand Derived from Cyclotriphosphazene

Solvothermal reactions of hexakis(4-carboxyphenoxy)cyclotriphospazene (H 6 L1) with copper ions in DMF/H 2 O produced one complex, {[Cu 6 (L1) 2 (OH)(H 2 O) 3 ]·guest} n ( 1 ), but with copper ions and auxiliary rigid 4,4-bipyridine (bpy) produced another new complex, namely, {[Cu 3 (L1)(bpy)(H 2 O) 6 ]·guest} n ( 2 ). These complexes had been characterized by IR spectroscopy, elemental analysis, and X-ray structural determination. 1 exhibits a 3D anionic structure with the binodal 4,8-connected network with Schläfli symbol {4 6 } 2 {4 9 ·6 18 ·8}, consisting of Cu 6 clusters and L1 ligands. In contrast, complex 2 possesses a different 3D network with trinodal 3,4,6-c topology with Schläfli symbol {4·6 2 } 2 {4 2 ·6 6 ·8 5 ·10 2 }{6 4 ·8·10}. In these two complexes, the semirigid hexacarboxylate ligands adopt distinct conformations to connect metal ions/clusters, which must be ascribed to the addition of the auxiliary rigid ligand in reaction systems. In addition, gas absorption properties of 1 and 2 including CO 2 and N 2 were further investigated.