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.

TADF and X-ray Radioluminescence of New Cu(I) Halide Complexes: Different Halide Effects on These Processes

A series of complexes [Cu2X2(Pic3PO)2] (X = Cl, Br, I) based on tris(pyridin-2-ylmethyl)phosphine oxide (Pic3PO) has been synthesized. At 298 K, these compounds exhibit thermally activated delayed fluorescence (TADF) of 1(M+X)LCT type with λmax varying from 485 to 545 nm, and quantum efficiency up to 54%. In the TADF process, the halide effect appears as the emission intensification and bathochromic shift of λmax in the following order X = I < Br < Cl. Upon X-ray irradiation, the title compounds emit radioluminescence, the emission bands of which have the same shape as those at TADF, thereby meaning a similar radiative excited state. By contrast to TADF, the halide effect in the radioluminescence is reversed: its intensity grows in the order X = Cl < Br < I, since heavier atoms absorb X-rays more efficiently. These findings essentially contribute to our knowledge about the halide effect in the photo- and radioluminescent Cu(I) halide emitters.

Tris(2-Pyridyl)Arsine as a New Platform for Design of Luminescent Cu(I) and Ag(I) Complexes

The coordination behavior of tris(2-pyridyl)arsine (Py₃As) has been studied for the first time on the example of the reactions with CuI, CuBr and AgClO₄. When treated with CuI in CH₂Cl₂ medium, Py₃As unexpectedly affords the scorpionate complex [Cu(Py₃As)I]∙CH₂Cl₂ only, while this reaction in MeCN selectively leads to the dimer [Cu₂(Py₃As)₂I₂]. At the same time, the interaction of CuBr with Py₃As exclusively gives the dimer [Cu₂(Py₃As)₂Br₂]. It is interesting to note that the scorpionate [Cu(Py₃As)I]∙CH₂Cl₂, upon fuming with a MeCN vapor (r.t., 1 h), undergoes quantitative dimerization into the dimer [Cu₂(Py₃As)₂I₂]. The reaction of Py₃As with AgClO₄ produces complex [Ag@Ag₄(Py₃As)₄](CIO₄)₅ featuring a Ag-centered Ag₄ tetrahedral kernel. At ambient temperature, the obtained Cu(I) complexes exhibit an unusually short-lived photoluminescence, which can be tentatively assigned to the thermally activated delayed fluorescence of (M + X) LCT type (M = Cu, L = Py₃As; X = halogen). For the title Ag(I) complexes, QTAIM calculations reveal the pronounced argentophilic interactions for all short Ag∙∙∙Ag contacts (3.209–3.313 Å).

Structural characterization and luminescence properties of trigonal Cu(i) iodine/bromine complexes comprising cation–π interactions

Trigonal copper(i) complexes comprising cation–π interactions achieve satisfactory photoluminescence properties.

Pyridylarsine-based Cu(I) complexes showing TADF mixed with fast phosphorescence: a speeding-up emission rate using arsine ligands

Can arsine ligands be preferred over similar phosphines to design Cu(I)-based TADF materials? The present study reveals that arsines can indeed be superior to reach shorter decay times of Cu(I) emitters. This has been exemplified on a series of bis(2-pyridyl)phenylarsine-based complexes [Cu₂(Py₂AsPh)₂X₂] (X = Cl, Br, and I), the emission decay times of which are significantly shorter (2-9 μs at 300 K) than those of their phosphine analogs [Cu₂(Py₂PPh)₂X₂] (5-33 μs). This effect is caused by two factors: (i) large ΔE(S₁-T₁) gaps of the arsine complexes (1100-1345 cm^-1), thereby phosphorescence is admixed with TADF at 300 K, thus reducing the total emission decay time compared to the TADF-only process by 5-28%; (ii) higher SOC strength of arsenic (ζ_l = 1202 cm^-1) against phosphorus (ζ_l = 230 cm^-1) makes the k_r(T₁ → S₀) rate of the Cu(I)-arsine complexes by 1.3 to 4.2 times faster than that of their phosphine analogs. It is also noteworthy that the TADF/phosphorescence ratio for [Cu₂(Py₂AsPh)₂X₂] at 300 K is halogen-regulated and varies in the order: Cl (1 : 1) < Br (3 : 1) ≈ I (3.5 : 1). These findings provide a new insight into the future design of dual-mode (TADF + phosphorescence) emissive materials with reduced lifetimes.

Coordination-driven supramolecular syntheses of new homo- and hetero-polymetallic Cu(i) assemblies: solid-state and solution characterization

New luminescent Cu(i) discrete assemblies D and FM and 1D coordination polymer E are reported. Deep insights of self-assembly processes based on flexible Cu(i) precursors are highlighted together with the preservation in solution of Cu(i) assemblies.