A series of four novel heteroleptic Cu(I) complexes, bearing bis(1H-indazol-1-yl)methane analogues as N,N ligands and DPEPhos as the P,P ligand, were synthesised in high yields under mild conditions and characterised by spectroscopic and spectrometric techniques. In addition, the position of the carboxymethyl substituent in the complexes and its effect on the electrochemical and photophysical behaviour was evaluated. As expected, the homoleptic copper (I) complexes with the N,N ligands showed air instability. In contrast, the obtained heteroleptic complexes were air- and water-stable in solid and solution. All complexes displayed green-yellow luminescence in CH₂Cl₂ at room temperature due to ligand-centred (LC) phosphorescence in the case of the Cu(I) complex with an unsubstituted N,N ligand and metal-to-ligand charge transfer (MLCT) phosphorescence for the carboxymethyl-substituted complexes. Interestingly, proper substitution of the bis(1H-indazol-1-yl)methane ligand enabled the achievement of a remarkable luminescent yield (2.5%) in solution, showcasing the great potential of this novel class of copper(I) complexes for potential applications in luminescent devices and/or photocatalysis.

Three new heteroleptic copper(I) complexes of the form [Cu(N,N)(XantPhos)]PF₆ were synthesized and characterized, where N,N refers to phenyl-substituted imidazo[4,5-f][1,10]phenanthroline. All complexes were obtained as yellow powders in yields ranging 82–95% and were fully characterized by NMR spectroscopy, FT-IR, and mass spectrometry. The complexes were also redox-optically characterized. Their absorption profiles display a lower-energy metal-to-ligand charge-transfer (MLCT) band at approximately 412 nm. In solution, weak dual emission is observed, combining ligand-centered and MLCT contributions, with oxygen-dependent quenching supporting the presence of triplet character in the latter. Temperature- and solvent-dependent studies reveal thermally coupled emissive states, in which a relaxed ³MLCT state dominates at low temperatures. In the solid state, intense orange-to-red emission arises from restricted molecular motion and stabilized ³MLCT states, with C3 showing the highest efficiency. Additionally, aggregation-induced emission (AIE) is observed in solvent mixtures. These results suggest that remote substitution can influence the excited-state dynamics and aggregation-driven emission in Cu(I) complexes.

In this work we have successfully synthesized five new heteroleptic copper(I) complexes (C1–5), bearing N,N ligands derived from dipyridylamine and S-BINAP as the P,P auxiliary ligand. All complexes were structurally characterized using NMR, FT-IR, and elemental analysis. Furthermore, the molecular structures of C1, C4, and C5 were determined via X-ray diffraction analysis. The photophysical properties of all complexes were assessed using UV-Vis spectroscopy and spectrofluorometric measurements in dichloromethane solution the solid state. All complexes displayed absorption bands at lower energies, attributed to spin-allowed MLCT transitions. In degassed dichloromethane solution at room temperature, all complexes exhibited broad luminescence in the visible spectrum, mainly assigned to MLCT/LLCT phosphorescence, with excited state lifetimes in the μs time regime. Besides, all complexes were assessed as photoredox catalysts in chlorosulfonylation and bromonitromethylation reactions of styrene, showing remarkable performances, thus highlighting the privileged role of the dpa ligand for the design of Earth-abundant metal photocatalysts.

In this study, we report the synthesis and characterization of three Cu(I) complexes bearing functionalized dipyridylamine ligands and DPEphos. Structural analysis confirms a distorted tetrahedral coordination environment around the metal center. Photophysical studies in DMSO show similar absorption profiles (λ_abs ≈ 341–343 nm) with ligand-centered and MLCT transitions, while emission spans the visible region (λ_emi = 410–483 nm) and is strongly influenced by ligand substitution, with the CF₃ derivative displaying a marked red shift. Emission is insensitive to oxygen and exhibits short lifetimes (τ ≈ 14.9–15.3 ns), suggesting short-lived ¹MLCT excited states. Biological evaluation in A375 melanoma cells reveals that all complexes exhibit low-micromolar cytotoxicity under dark conditions (IC₅₀ = 3.33–4.92 μM). Notably, only the CF₃-substituted complex shows a significant light-induced enhancement of activity upon irradiation at 390 nm (IC₅₀ = 1.18 μM), indicating photoactivation.