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.

Hexanuclear Copper(I) Hydride from the Reduction-Induced Decarboxylation of a Dicopper(II) Formate

“…The lifetime of this emission was determined to be 6.24 ns at room temperature (Figure S33). The observation of luminescence is quite typical for multinuclear coinage metal d 10 complexes with M 3 units. − …”

Synthesis, Photophysical Properties, and Computational Analysis of Di- and Tetranuclear Alkyne Complexes of Copper(I) Supported by a Highly Fluorinated Pyrazolate

“…The copper­(I) adduct {[3,5-(CF 3 ) 2 Pz]­Cu} 3 represents the most celebrated example reported by members of this team a few years ago. ,− It exhibits bright phosphorescent emissions both in the solid state and in solution under UV excitation that can be easily fine- and coarse-tuned to multiple visible colors by varying the solvent, copper adduct concentration, temperature, excitation wavelength, and/or medium rigidity. ,, Detailed studies on solid {[3,5-(CF 3 ) 2 Pz]­Cu} 3 samples suggest that these emissions originate from an excited state that modifies the intertrimer closed-shell cuprophilic interactions in the ground state to become covalent in the phosphorescent Cu–Cu centered excimer. − The mixed Cu–Au metal systems derived from {[3,5-(CF 3 ) 2 Pz]­Cu} 3 and trinuclear gold­(I) imidazolate complexes show near-unity photoluminescence quantum yields . Various other trinuclear copper pyrazolate adducts are also known for their interesting chemistry and remarkable photophysical features, including some showing luminescence responses due to mechanical action and pressure changes, acid–base chemistry, and volatile organic chemical detection. ,,,− …”

Complexes of Trinuclear Macrocyclic Copper(I) and Silver(I) 3,5‐Bis(Trifluoromethyl)Pyrazolates with Ketones

“…For example, [{3,5‐(CF 3 ) 2 Pz}Au] 3 is a π‐acid, whereas [{3,5‐(CH 3 ) 2 Pz}Au] 3 is a π‐base 8. Polymer complexes based on copper trimeric pyrazolates with halide/pseudohalide interactions were described in 2011 9. The ability of trinuclear metal pyrazolates to form interesting complexes with organic arenes as bases was shown 8.…”