Crystal structures and fluorescence property of rare earth complexes {La[o-C6H4(NO2)(CO2)]3•(DMF)2}2

The o-nitro-benzoic acid (C7H5O4N) and N, N-dimethylformamide (DMF) coordinate with La (III) to form a dinuclear complex La [o-C6H4 (NO2) (CO2)](3) . (DMF)(2) vertical bar(2). The complex resides on an inversion center. The structure of the complex is characterized by IR, H-1 NMR, C-13 NMR, UV and fluorescent emission spectra. The results show that the complex crystallizes in a triclinic system, space group PI, cell parameter a = 1. 902 (2) nm, b = 1. 245 0 (2) nm, c = 1. 298 7 (2) nm, alpha = 64. 555 (2)degrees, beta = 66. 348 (2)degrees, gamma = 71. 920 (2)degrees, V = 1. 569 5 (5) nm(3), D-c = 1. 658 Mg/m(3), Z = 2, mu = 1. 437 mm(-1), F (000) = 784. In the complex, two La(III) are bridged by four o-nitro-benzoic acids liganding with their carboxyl. The coordination number of La(III) is nine and the coordinated atoms are all oxygen from the carboxyl and carbonyl. Nine oxygen atoms(seven from a carboxyl of o-nitro-benzoic acid and two from DMF molecule) occupy the nine coordination sites around La(III), respectively. Hydrogen bonds and aromatic pi...pi stacking interactions assemble the title complex into a three dimensional network. Luminescence measurement shows that the complex emits fluorescence.