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 ((3)CC) excited state.

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A series of Cu(i) halide complexes showing thermally activated delayed fluorescence (TADF) combined with room temperature phosphorescence are reported.

The unique L 2 Cu 6 I 6 complexes containing two Cu 3 I 3 units have been obtained via reaction of 1,5-diaza-3,7-diphosphacyclooctanes bearing ethylpyridyl substituents at phosphorus atoms with an excess of copper iodide. The structure of one of the complexes was confirmed by X-ray diffraction. It was shown that the complexes can exist in two crystalline phases with different parameters of the unit cell, which were detected by the PXRD data analyses. The solvent-free crystalline phases of the complexes display rare solid-state white emission at room temperature, which is observed due to the presence of two broad bands in the emission spectra with maxima at 464 and 610 nm. Quantum chemical computations show that the high-energy band has 3 (M+X)LCT origin, whereas the low-energy band is interpreted as 3 CC. The quantum yields of white luminescence of complexes reach 15−20%.

We report on the potential application of NIR–to–NIR Nd3+-doped yttrium vanadate nanoparticles with both emission and excitation operating within biological windows as thermal sensors in 123–873 K temperature range. It was demonstrated that thermal sensing could be based on three temperature dependent luminescence parameters: the luminescence intensity ratio, the spectral line position and the line bandwidth. Advantages and limitations of each sensing parameter as well as thermal sensitivity and thermal uncertainty were calculated and discussed. The influence of Nd3+ doping concentration on the sensitivity of luminescent thermometers was also studied.

Development of new approaches to the noncontact optical thermometry is of great importance for modern science and technology. In the current work, single-phase YVO 4 :Eu 3+ nanoparticles prepared via the modified Pechini technique were studied as luminescence thermometers. Thermal sensing was performed using two different ratiometric approaches: utilizing the luminescence intensity ratio between transitions emitted from two thermally coupled excited levels (emission spectrum) and between transitions originating from different thermally coupled low-lying levels (excitation spectrum). The first technique allows determining temperature within the 298−873 K range, whereas the second one allows determining temperature within 298−473 K. The spectral position of the 5 D 0 (1)− 7 F 1 (2) band was also suggested as a temperaturedependent parameter. Thermometric performance of YVO 4 :Eu 3+ nanophosphors including absolute and relative sensitivities, minimum temperature uncertainty, and repeatability was obtained and discussed.

The position of activator ions in the lattice has a fundamental effect on the luminescent properties of phosphors.