A novel type of cyclic P,N-ligands, pyridyl containing phospholanes, has been synthesized in a moderate yield by the reaction of primary phosphines with 1,4-dichlorobutane in a superbasic medium. A series of homo tetranuclear octahedral Cu₄I₄L₂, dinuclear tetrahedral Cu₂I₂L₃, and dinuclear “head-to-tail” Cu₂I₂L₂ luminescent complexes with these ligands were obtained. All the compounds were characterized using a range of spectroscopic and computational techniques, and in the case of some Cu₄I₄L₂ and Cu₂I₂L₃ complexes, by single crystal X-ray diffraction. The structural diversity of the obtained complexes was reflected in their photophysical properties: phosphorescence spectra of the compounds display emission in broad spectral range of 471–615 nm. TD-DFT computations allow the assignment of a single emission band around 550 nm for Cu₂I₂L₃ complexes and 471 nm for Cu₂I₂L₂ complex to a vertical triplet–singlet transition from a metal-to-ligand and halide-to-ligand charge-transfer ³(M + X)LCT excited state, whereas a second band at around 600 nm in the spectra of octahedral Cu₄I₄L₂ complexes was assigned predominantly to Cu₄I₄ cluster-centered (³CC) excited state.

Tertiary diethylpyridylphosphine was synthesized by the reaction of pyridylphosphine with bromoethane in a suberbasic medium. The reaction of phosphine with the copper(I) iodide led to the formation of a copper(I) coordination polymer, which, according to the X-ray diffraction data, has an intermediate structure with a copper-halide core between the octahedral and stairstep geometries of the Cu₄I₄ clusters. The obtained coordination polymer exhibits a green emission in the solid state, which is caused by the ³(M+X)LCT transitions. The heating up of the copper(I) coordination polymer to 138.5 °C results in its monomerization and the formation of a new solid-state phase. The new phase exhibits a red emission, with the emission band maximum at 725 nm. According to the experimental data and quantum chemical computations, it was concluded that depolymerization probably leads to a complex that is formed with the octahedral structure of the copper-halide core. The resulting solid-state phase can be backward-converted to the polymer phase via recrystallization from the acetone or DMF. Therefore, the obtained coordination polymer can be considered a sensor or detector for the overheating of processes that should be maintained at temperatures below 138 °C (e.g., engines, boiling liquids, solar heat systems, etc.).

A family of helical dinuclear copper(I) pyridylphospholane complexes [Cu₂L₃X]X (X = BF₄ ⁻, Cl⁻ and Br⁻) was prepared. The family includes the first examples of this type of complex based on copper(I) chloride and copper(I) bromide. The two isomers typical of this class of compounds, namely head-to-head and head-to-tail complexes, were studied in solution by spectroscopic and optical methods, and in the solid state by X-ray diffraction. Furthermore, the solid-state luminescence of the complexes at different temperatures was studied, and the results were interpreted using quantum-chemical calculations. It was shown that the luminescence of the complexes is attributed to the ³(M + X)LCT transitions.