title: Trinuclear-based copper(I) pyrazolate polymers: effect of trimer π-acid···halide/pseudohalide interactions on the supramolecular structure and phosphorescence.
abstract: Under different situations, solvothermal reactions of 3,5-diethyl-4-(4-pyridyl)-pyrazole (HL) with CuX or CuX(2) (X = Cl, Br, I, and SCN) afforded five copper(I) coordination polymers, {CuX[CuL](3)·solvent}(n) (X = Cl, 1; Br, 2; I, 3; X = SCN and solvent = MeCN, 4) and {Cu(2)I(2)[CuL](3)}(n) (5). X-ray diffraction analyses show that all the complexes have trinuclear [CuL](3) (referred as Cu(3)) secondary building units featuring planar nine-membered Cu(3)N(6) metallocycles with three peripheral pyridyl groups as connectors, which are further linked by CuX or Cu(2)X(2) motifs to generate single- or double-strand chains. Interestingly, the Cu(I) atoms within the Cu(3) units in 1-5 behave as coordinatively unsaturated π-acid centers to contact soft halide/pseudohalide X atoms of CuX and Cu(2)X(2) motifs, which lead to novel sandwich substructures of [(Cu(3))(Cu(2)X(2))(Cu(3))] (X = Br, I, and SCN) in 2-4. In addition, both the π-acid [Cu(3)]···X contacts and intertrimer Cu···Cu interactions contribute to the one-dimensional (1D) double-strand and 2D/3D supramolecular structures of 1-5. All of these complexes exhibit high thermostability and bright solid-state phosphorescence upon exposure to UV radiation at room temperature. The emissions arise from the mixtures of metal-centered charge transfer, metal to ligand charge transfer, and halide-to-ligand charge transfer excited states, and can be tuned by intermolecular π-acid [Cu(3)]···halide/pseudohalide contacts.
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, P. R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Hou
authors.forename: Wen-Juan
authors.initials: WJ
authors.lastname: Shi
authors.forename: Yao-Yu
authors.initials: YY
authors.lastname: Wang
authors.forename: Hai-Hua
authors.initials: HH
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Cui
authors.forename: Peng-Xiang
authors.initials: PX
authors.lastname: Chen
authors.forename: Qi-Zhen
authors.initials: QZ
authors.lastname: Shi