In this study, all-inorganic copper halide salt K₂Cu₂Cl₆ single-crystal and thin films were prepared. The single-crystal diffraction data belonged to the monoclinic K₂Cu₂Cl₆ (space group = P₂(1)/C, unit cell parameters of a = 4.0340 Å, b = 13.7987 Å, c = 8.7445 Å, α = 90.000, β = 97.123, and γ = 90.000). As far as we know, this is the first study of the copper halide salt K₂Cu₂Cl₆ for optoelectronic applications. The band gap of K₂Cu₂Cl₆ is calculated to be approximately 1.85 eV. A low-cost photodetector based on the K₂Cu₂Cl₆ thin film was efficient under different monochromatic light from 330 to 390 nm with different chopping frequencies (1.33–30 Hz). Density functional theory (DFT) computational results indicate that the valence bands (VBs) and conduction bands (CBs) are shifted up in energy using the orbital-dependent correction to the DFT energy. Partial density of states reveals that the VBs and narrow CBs are derived from the hybrid orbitals of Cu²⁺ 3d and Cl^– p, respectively.

Excited state hydrogen-bonding dynamics of coumarin in ethanol solvent has been studied using TDDFT/6-311++G(d,p) and a conductor-like polarizable continuum model. The geometry, hydrogen bond binding energy and frequency analysis indicate that the intermolecular hydrogen bond between C102 and ethanol is strengthened in the excited state. The binding energy is increased from 27.81 kJ mol−1 in the ground state to 32.36 kJ mol−1 in the S1 state. The CO and O–H stretching bands in C102–EtOH are strongly red-shifted due to the formation of the intermolecular hydrogen bond. In the excited state, redshift occurs for the CO and O–H in the C102–EtOH complex. The excitation energy and frontier molecular orbital analysis indicate that S1 of the C102–EtOH complex is the locally excited state. S1 corresponds to the orbital transition from the HOMO to the LUMO with the ππ* character. Furthermore, the internal conversion from the excited to ground state is enhanced by hydrogen bond strengthening.

The oxidative dehydrogenation (ODH) reaction mechanism of ethane and propane catalyzed by two kinds of oxygen-species-terminated BN materials, namely BN nanotubes and h-BN, was studied by the B3LYP-D3 functional with the 6-31G(d,p) basis set. On the atomic-oxygen-species-terminated active sites, two hydrogen atoms of the alkane were abstracted to form an alkene in a concerted way, which was more favourable than the stepwise mechanism from kinetic and thermodynamic viewpoints. The concerted way could lead to excellent selectivity to alkenes because without intermediate to side-product. The steric structural match between the alkane and oxygen species was thought to be the major effect factor to determine the ODH mechanism. Active oxygen species were recovered through the hydroxyl coupling into water with an activation energy (238.17 kJ mol⁻¹) close to experimental data (253 kJ mol⁻¹). By investigating the transformation kinetics from hydroxyl-terminated species to active-oxygen-terminated species, the active-site regeneration was speculated to be the rate-limiting step of ODH. Stepwise oxidative dehydrogenation happening in a rebound mechanism could explain the formation of CO_x side-product, although its activation energy was much larger than that for the concerted way. The propyl intermediate kinetically favourably proceeded through a second hydrogen abstraction to form propylene rather than C–C bond cleavage to form ethylene. These results would provide helpful information to precisely design oxygen-functionalized BN catalysts for ODH.