An Unusual(3,11)-Connected Network Constructed by Tri-nuclear Lanthanide Building Units and Mixed Ligands

Under hydrothermal conditions, a new lanthanide coordination polymer, [Er;（oba）;（na）]n(1, oba = 4,4’-oxybis（benzoate）, na = nicotinic acid) has been synthesized. Compound 1 shows a 3D framework by incorporating tri-nuclear [Er;（COO）;] unit and the mixed ligands of oba;and na;. It is interesting that decarboxylation occurred in the ortho position and 2,3-pyridinedicarboxylic acid was partially transformed into na under hydrothermal conditions. Compound 1 can be reduced into a（3,11）-connected net and displays weak second-harmonic generation response. Furthermore, the PXRD, TGA and IR spectra were also studied.