A series of red-emissive {Cu₄I₆} clusters have been synthesized from alkyl-tris(2-pyridyl)phosphonium halides, [R-PPy₃]Hal, and CuI. The size of the alkyl substituent (R) has a dramatic impact on the structure of the clusters assembled. [Me-PPy₃]I salt reacts with CuI (1 : 2) to give the ionic [Cu(Me-PPy₃)I]₂Cu₂I₄ complex consisting of the scorpionate [Cu(N,N′,N′′-Me-PPy₃)I]⁺ cation. Under similar conditions, [Pr-PPy₃]I forms the zwitterionic [Cu₄I₆(Pr-TPP)₂] complex containing an unusual stepwise [Cu₄I₆] cluster core. The use of [Bu-PPy₃]I or [Bn-PPy₃]I in this reaction leads to zwitterionic [Cu₄I₆(R-TPP)₂] complexes, in which a linear-shaped [Cu₄I₆] module appears. Photophysical studies supported by TD-DFT computations have revealed that the title complexes in the solid state at 298 K exhibit a red photoluminescence (λ^em _max = 620–650 nm) with short lifetimes (0.04–2.10 μs), which are assigned to the thermally activated delayed fluorescence (TADF) mixed with the cluster centered (³CC) phosphorescence. The compounds synthesized are the first red-emitting representatives of the recently discovered family of zwitterionic CuI-based complexes (so-called “AIO” structures).

A series of isostructural 1D coordination polymers bearing stair-step [Cu₄X₄] modules is reported. At ambient temperature, they feature bright halogen-modulated colorful luminescence spanning from deep blue to green.

A family of brightly luminescent dinuclear complexes of [Cu(μ₂-X)(N^N)]₂ type (X = I or SCN) has been synthesized in 76–90% yields by the reaction of bis(2-pyridyl)phosphine oxides (N^N) with the corresponding Cu(I) salts. The X-ray diffraction study reveals that the Cu₂I₂ core of the [Cu(μ₂-I)(N^N)]₂ complexes has either a butterfly- or rhomboid-shaped structure, while the eighth-membered [Cu(^SCN _NCS)Cu] ring in the [Cu₂(SCN)₂(N^N)]₂ complexes is nearly planar. In the solid state, these compounds exhibit a strong green-to-yellow emission (λ^em _max = 536–592 nm) with high PLQYs (up to 63%) and short lifetimes (1.9–10.0 μs). The combined photophysical and DFT study indicates that the ambient-temperature emission of the complexes obtained can be assigned to the thermally activated-delayed fluorescence (TADF) from the ¹(M + X)LCT excited state, while at 77 K, phosphorescence from the ³(M + X)LCT state is likely observed.

Phosphine readily adds to 1-(tert-butyl)-4-vinylbenzene in the KOH–DMSO system (70–120 °C, 3 h, atmospheric pressure) to form bis[4-(tert-butyl)phenethyl]phosphine and tris[4-(tert-butyl)phenethyl]phosphine, which are further oxidized to corresponding phosphine oxides, sulfides and selenides.