Synthesis, Structure, Luminescence and Theoretical Investigations on a New Tin Complex with (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic Acid

A new tin complex Sn(CH(3)HPPDA)Cl-4 (1) was prepared from SnCl4 center dot 5H(2)O with (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid (H(2)PPDA) by solvothermal reaction in methanol, and characterized by single-crystal X-ray difflaction analysis, optical absorption spectrum and photoluminescence. Compound 1 crystallizes in a monoclinic centrosymmetric space group of P2(1)/c with a = 12.418(2), b = 11.9467(12), c = 15.845(3) angstrom, beta = 107.948(7)degrees, V = 2236.2(6) angstrom(3), Z = 4, M-r = 594.78, D-c = 1.767 g/cm(3), mu = 1.651 mm(-1), F(000) = 1160, S = 1.023 and T = 293(2) K. The final R = 0.0847 and wR = 0.2431 for 3144 observed reflections with I > 2 sigma(I). The discrete mononuclear Sn(CH(3)HPPDA)Cl-4 complex is connected into a supramolecular network of 1 by intramolecular and intermolecular C-H center dot center dot center dot O and intermolecular C-H center dot center dot center dot Cl hydrogen bonding interactions. Compound 1 displays fluorescence with a lifetime value of about 7.58 ns in the visible region under visible-light excitation, and the origin of the luminescent emission is primarily assigned to the combination of intraligand charge-transfer of CH(3)HPPDA and Cl--to-CH(3)HPPDA charge-transfer mechanism which is probed by the density of states (DOS) calculations.