In situ alkylation of N-heterocycles in organic templated cuprous halides

Five new cuprous halides formulated as [etpy][Cu3I4] 1, [mepy][Cu2Br3] 2, [mepy][Cu2I3] 3 [dmebpp][Cu7Br9] 4 and [dmeDABCO](4)[Cu8I16] 5 (etpy = N-ethylpyridyl; mepy = N-methylpyridyl; dmebpp = N, N'-dimethyl-1,3-bis(4-pyridyl) propane; dmeDABCO = N, N'-dimethyl-1,4-diazabicyclo-[2.2.2] octane) have been prepared by solvothermal reactions of a copper source, halides and N-heterocyclic ligands in alcoholic solution. 1 contains an unprecedented trigonal two-dimensional cuprous halide layer Cu3I4- constructed from trimeric Cu3I8 units via sharing peripheral mu(3)-iodines; isostructural 2 and 3 contain infinite Cu2X3- chains in which the copper atoms are arranged into a ladder; 4 is composed of novel twofold helical cuprous halide chains Cu7Br92- built up by CuBr4 and CuBr3; 5 contains an infinite edge-sharing tetrahedral chain with a periodic sequence of eight CuI4 tetrahedra. In situ alkylation reactions of N-heterocycles with alcohols generated organic cationic templates, which played an important role in the control of the structures of anionic cuprous halides. A possible alkylation mechanism of N-heterocycles in the system has been proposed. The fluorescence properties of 1 and 4 were investigated. Time-dependent density functional theory (TD-DFT) calculations were carried out on the excited electronic states of 1 in order to understand the emission mechanism.