Crystal Structure and Spectroscopic Analysis of Polypyridyl Quinoxaline with Ce(III) and Nd(III)

Two high coordination crystals were obtained by the interaction of Ce3+ and Nd3+ with polypyridyl quinoxaline ligand 2,3,6,7,10,11-hexakis(2-pyridyl)dipyrazino[2,3-f:20,30-h]quinoxaline (HPDQ), and they were characterized. Complex 1 exhibits a 0 dimensional three-nuclear structure, with the three Ce(III) atoms being ten-, eleven-and twelve-coordinated. Complex 2 is a 0 dimensional dual-core structure and the Nd(III) atom is ten-coordinated. Complex 1 is of monoclinic system, space group P2/c with a = 16.850(3), b = 16.617(3), c = 24.017(5) angstrom, beta = 100.94(3)degrees, V = 6602(2) angstrom(3), Z = 4, S = 1.062, F(000) = 3372, R = 0.0504 and wR = 0.1463 (I > 2 sigma(I)). Complex 2 adopts a monoclinic system, space group C2/c with a = 25.795(5), b = 20.166(4), c = 13.059(3) angstrom, beta = 112.29(3)degrees, V = 6286(2) angstrom(3), Z = 4, S = 1.004, F(000) = 2664, R = 0.0663 and wR = 0.1821 (I > 2 sigma(I)). Furthermore, the behaviors of HPDQ with Ce3+ and Nd3+ in the solution are also investigated. After the Ce3+ is added, the ultraviolet absorption of the solution is enhanced with a red shift compared with that of the HPDQ ligand. While after adding Nd3+, the ultraviolet absorption of the solution is weakened, and it has a red shift which is the same as Ce3+. However, after the respective addition of metal ions, the emission of all solutions is quenched and has a red shift compared with that of the HPDQ ligand.