A family of CuI-based 1D polymers showing colorful short-lived TADF and phosphorescence induced by photo- and X-ray irradiation

Exploiting 2-(alkylsulfonyl)pyridines as 1,3-N,S-ligands, herein we have constructed 1D CuI-based coordination polymers (CPs) bearing unprecedented (CuI)_n chains and possessing remarkable photophysical properties. At room temperature, these CPs show efficient TADF, phosphorescence or dual emission in the deep-blue to red range with outstandingly short decay times of 0.4-2.0 μs and good quantum performance. Owing to great structural diversity, the CPs demonstrate a variety of emissive mechanisms, spanning from TADF of ¹(M + X)LCT type to ³CC and ³(M + X)LCT phosphorescence. Moreover, the designed compounds emit strong X-ray radioluminescence with the quantum efficiency of up to an impressive 55% relative to all-inorganic BGO scintillators. The presented findings push the boundaries in designing TADF and triplet emitters with very short decay times.

Copper(i)–iodide cluster structures as functional and processable platform materials

This review provides a complete overview of the progress towards implementation of CuI-nanoclusters in functional materials and devices.

Structural Diversity of Copper(I) Cluster-Based Coordination Polymers with Pyrazine-2-thiol Ligand

Six novel copper(I) cluster-based coordination polymers (CPs) [Cu₉(pzt)₇Cl₂]_n (1), [Cu₂(pzt)Cl]_n (2), [Cu₄(pzt)₃Br]_n (3), [Cu(pzt)]_n (4), [Cu₄(pzt)₃I]_n (5), and [Cu₇(pzt)₆I]_n (6) were solvothermally synthesized using Hpzt (Hpzt = pyrazine-2-thiol) ligand and well-characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD). Six CPs exhibit either 2D (4 and 6) or 3D (1-3, and 5) network based on diverse multinuclear {Cu_xS_y} clusters. The structural evolutions of 1-6 are greatly influenced by types of metal halides and the ligand-to-metal molar ratio used in the reaction. Among them, compound 1 displays interesting temperature-dependent photoluminescence arising from triplet cluster-centered (³CC) excited state from the cluster metal core. Compounds 1-6 also exhibit photocurrent responses upon visible-light illumination (λ = 420 nm) in the order 6 > 5 > 3 > 1 > 4 > 2. This work not only shows the structural diversity of {Cu_xS_y} clusters-based CPs but also provides an interesting insight into structural modulation using crystal engineering concept.

Supramolecular Interactions Modulating Electrical Conductivity and Nanoprocessing of Copper-Iodine Double-Chain Coordination Polymers

Two coordination polymers (CPs), based on Cu(I)-I double zig-zag chains bearing isonicotinic acid or 3-chloroisonicotinic acid as terminal ligands with molecular recognition capabilities, have been synthesized and fully characterized. Both compounds present extended networks with supramolecular interactions directed by the formation of H-bonds between the complementary carboxylic groups, giving supramolecular sheets. The chloro substituent allows establishing additional Cl···Cl supramolecular interactions that reinforce the stability of the supramolecular sheets. These CPs are semiconductor materials; however, the presence of chlorine produces slight changes in the I-Cu-I chains, generating a worse overlap in the Cu-I orbitals, thus determining a decrease in its electrical conductivity value. These experimental results have also been corroborated by theoretical calculations using the study of the morphology of the density of states and 3D orbital isodensities, which determine that conductivity is mostly produced through the Cu-I skeleton and is less efficient in the case of the chloro derivative compound. A fast and efficient bottom-up approach based on the self-assembly of the initial building blocks and the low solutibility of these CPs has proved very useful for the production of nanostructures.

Reversible stimulus-responsive Cu(i) iodide pyridine coordination polymer

A coordination polymer based on CuI double chains with substituted pyrimidine is a dynamic and reversible material very sensible to both physical and chemical stimuli.

Relevant and unprecedented C-H/σ supramolecular interactions involving σ-aromatic M2X2 cores

A novel type of C-H/σ supramolecular interaction involving σ-aromatic M2X2 (M = Cu, Hg; X = Cl, Br, I, S) cores is reported for the first time. Three new polymeric coordination copper complexes, {[Cu(μ-Cl)(Cl)(μ-L)]2}n (1), {[Cu(μ-I)(μ-L)]2}n (2) and [Cu(Br)2(μ-L)(CH3CN)2]2 (3), have been synthesized with the organic ligand α,ω-bis(benzotriazoloxy)propane system (L) and halides as counterions. A very interesting C-H/σ supramolecular interaction has been observed in the solid state structure of compound 2, similar to a C-Hπ interaction, which has been confirmed by Bader's "atoms-in-molecules" AIM analysis. The Nucleus Independent Chemical Shift (NICs) method was used to evaluate the aromatic character of the different cores in this study. The influence of the nature of the metal ions, bridging atoms, oxidation states, and coordination environments around the metal centers on the strength of the aromaticity of the M2X2 cores was theoretically analyzed and explained. The binding ability of the 1-alkoxy-1,2,3-benzotriazole ring to establish π-π and C-H/π interactions and how its coordination to Cu(I) and Cu(II) ions affects the strength of the aforementioned interactions have been discussed. The electron deficient triazole ring and its π-acidity increases upon coordination of the Cu ion, leading to the formation of a lone pair (lp)-π interaction involving the five-membered ring of the ligand, which has also been analyzed. We have also analyzed the C-H/σ interactions of previously reported X-ray crystal structures of different coordination polymers based on a binuclear copper(I) complex and 2,3-dimethylpyrazine, dithioethers, and benzotriazol-1-yl-based pyridyl units as ligands using I- as a counter-ion. Complex 1 shows antiferromagnetic behavior with a magnetic coupling constant of J = -7.9 cm(-1). Moreover, photoluminescence and TGA studies of the complexes were also carried out.