Under different situations, solvothermal reactions of 3,5-diethyl-4-(4-pyridyl)-pyrazole (HL) with CuX or CuX2 (X = Cl, Br, I, and SCN) afforded five copper(I) coordination polymers, {CuX[CuL](3)center dot solvent}(n) (X = Cl, 1; Br, 2; l,3; X = SCN and solvent = MeCN, 4) and {Cu(2)l(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 Cu3N6 metallocycles with three peripheral pyridyl groups as connectors, which are further linked by CuX or Cu2X2 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 pi-acid centers to contact soft halide/pseudohalide X atoms of CuX and Cu2X2 motifs, which lead to novel sandwich substructures of [(Cu-3)(Cu2X2)(Cu-3)] (X = Br, 1, and SCN) in 2-4. In addition, both the pi-acid [Cu-3]center dot center dot center dot X contacts and intertrimer Cu center dot center dot center dot 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 pi-acid [Cu-3]center dot center dot center dot halide/pseudohalide contacts.