Synthesis and structural characterization of different topological coordination polymers based on tunable Cu4Br4−mIm secondary building units and macrocyclic azacalixaromatics

The coordination self-assembly between the macrocyclic ligand tetraazacalix4]pyrimidine (TAPM) with cubane-like copper halides (Cu₄X₄) produced five coordination polymers 1-5 {Cu₄Br_4−mI_m(TAPM)}_n (m=0 (1), 1 (2), 2 (3), 3 (4) and 4 (5)). X-ray single crystal analysis revealed that the Br:I ratio in the Cu₄X₄ cores serves as a controlling factor to fine-tune the geometries of Cu₄X₄ and therefore induce the conformation variation of tetraazacalix4]pyrimidine. Consequently, two different topological nets, dia and lcs, were successfully constructed based on tetrahedrally coordinated Cu₄X₄ secondary building units and the flexible macrocyclic quadridentate ligand TAPM. The structure details of 1-5 as porous materials are analyzed, which shows a solvent accessible volume within the range of 27−35%. Compounds 1-5 exhibit luminescence properties with the peak maximum at around 476−488 nm.