Crystal structure, fluorescence spectroscopy, and electrochemical property of two neodymium coordination polymers with phenoxy acids

Abstract

Two nine-coordination coordination polymers of neodymium, [Nd2(p-C8H4O4)(o-C8H4O4)2 • 4H2O]n (I), [Nd2(C10H4O8)(C10H2O8) • 2H2O]n (II), have been prepared by hydrothermal reaction of Nd(NO3)3 • 6H2O with terephthalic acid and phthalic acid, or benzenetetracarboxylic anhydride and determined by means of IR, UV, fluorescence, TG-DTA, cyclic voltammetry (CV) and X-ray single-crystal diffraction methods (CIF files CCDC nos. 1006206 (I), 979309 (II)). Yellow-green luminescence could been observed at 391 nm (λex = 305 nm) for complex I and 370 nm (λex = 331 nm) for the complex II. The emission of complexes I and II may be due to the π* → n transition, which may be assigned to the ligand-to-metal charge-transfer bands. Compared with complex II, the complex I exhibits a stronger fluorescence intensity for the different coordinated environment. Cyclic voltammetric measurement of the two compounds reveal that the compounds both have a couple of irreversible redox peak, indicating that the two polymers were both corresponded to the unusual Nd(III)/Nd(V).