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

Abstract

Five new cuprous halides formulated as [etpy][Cu(3)I(4)] 1, [mepy][Cu(2)Br(3)] 2, [mepy][Cu(2)I(3)] 3 [dmebpp][Cu(7)Br(9)] 4 and [dmeDABCO](4)[Cu(8)I(16)] 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 Cu(3)I(4)(-) constructed from trimeric Cu(3)I(8) units via sharing peripheral mu(3)-iodines; isostructural 2 and 3 contain infinite Cu(2)X(3)(-) chains in which the copper atoms are arranged into a ladder; 4 is composed of novel twofold helical cuprous halide chains Cu(7)Br(9)(2-) built up by CuBr(4) and CuBr(3); 5 contains an infinite edge-sharing tetrahedral chain with a periodic sequence of eight CuI(4) 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 1 of in order to understand the emission mechanism.