Increasing Structure Dimensionality of Copper(I) Complexes by Varying the Flexible Thioether Ligand Geometry and Counteranions

This work focuses on the systematic investigation of the influences of pyrimidine-based thioether ligand geometries and counteranions on the overall molecular architectures. A N-containing heterocyclic dithioether ligand 2,6-bis(2-pyrimidinesulfanylmethyl)pyridine (L1) and three structurally related isomeric bis(2-pyrimidinesulfanylmethyl)benzene (L2−L4) ligands have been prepared. On the basis of the self-assembly of CuX (X = I, Br, Cl, SCN, or CN) and the four structurally related flexible dithioether ligands, we have synthesized and characterized 10 new metal−organic entities, Cu₄(L1)₂I₄ 1, Cu₄(L1)₂Br₄ 2, [Cu₂(L2)₂I₂·CH₃CN]_n 3, [Cu(L3)I]_n 4, [Cu(L3)Br]_n 5, [Cu(L3)CN]_n 6, [Cu(L4)CN]_n 7, [Cu₂(L4)I₂]_n 8, [Cu₂(L4)(SCN)₂]_n 9, and {[Cu₆I₅(L4)₃](BF₄)·H₂O}_n 10, by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that the 10 Cu(I) complexes possess an increasing dimensionality from 0D (1 and 2) to 1D (3−5) to 2D (6−9) to 3D (10), which indicates that the ligand geometry takes an essential role in the framework formation of the Cu(I) complexes. The influence of counteranions and π−π weak interactions on the formation and dimensionality of these coordination polymers has also been explored. In addition, the photoluminescence properties of Cu(I) coordination polymers 4−10 in the solid state have been studied.