Assembly of CuBr and 1,6-bi(benzotriazole)hexane under solvothermal conditions modulated by alkali metal cations

The addition of alkali metal bromide effectively controlled the assembly processes of flexible 1,6-Bi(benzotriazole)hexane (BBTH) ligand and CuBr under solvothermal conditions, and led to four different crystalline solids, namely, {K[Cu6Br7](BBTH)}n (1), {[CuBr]4(BBTH)}n (2), {[CuBr]2(BBTH)}n (3), and Cs3Cu2Br5 (4). The cuprous bromide inorganic skeletons vary from [Cu4Br4] double chain (in 2), [Cu6Br7] zigzag ribbon (in 1), [Cu2Br2] single helix (in 3) to binuclear [Cu2Br5] cluster (in 4) with the alkali metal cations changing from Na+, K+, Rb+ to Cs+. Cisoid-BBTH ligands in 1 and 2 link adjacent inorganic chains to form 2D organic–inorganic hybrid layers, but transoid-BBTH in 3 connects cuprous bromide chain to give a 3D rod-packing framework.