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Constructing the hetrostructure is a feasible strategy to enhance the performances of photocatalysts. However, there are still some fundamental details and mechanisms for the specific design of photocatalysts with heterostructure, which need further confirming and explain. In this work, g-C3N4-based heterostructures are constructed with TiO2 in different ways, and their intrinsic factors to improve the photocatalytic activity are systematically studied by density functional theory (DFT). When g-C3N4 combines horizontally with TiO2 to form a heterostructure, the interaction between them is dominated by van der Waals interaction. Although the recombination of photo-generated electron–hole pair cannot be inhibited significantly, this van der Waals interaction can regulate the electronic structures of the two components, which is conducive to the participation of photo-generated electrons and holes in the photocatalytic reaction. When the g-C3N4 combines vertically with TiO2 to form a heterostructure, their interface states show obvious covalent features, which is very beneficial for the photo-generated electrons’ and holes’ transport along the opposite directions on both sides of the interface. Furthermore, the built-in electric field of g-C3N4/TiO2 heterostructure is directed from TiO2 layer to g-C3N4 layer under equilibrium, so the photo-generated electron–hole pairs can be spatially separated from each other. These calculated results show that no matter how g-C3N4 and TiO2 are combined together, the g-C3N4/TiO2 heterostructure can enhance the photocatalytic performance through corresponding ways.

Several 2-heteroaryl-, 2-heteroarylcarbonylmethyl-, 2-arylcarbonylmethyl, and 2-arylethyl derivatives of S-dihydro(alkyloxy)benzyloxypyrimidines have been synthesized and the anti-HIV activities of these compounds were tested in C8166 cell and against RT enzyme. It was found that some of these compounds showed good activity against HIV-1 (EC 50 = 0.014–0.8 μM) with low toxicity (CC 50 value of 222–564 μM) and high selectivity (SI value of 278–37743). The structure-activity relationships (SAR) of these compounds have also been discussed.

The crystal structure, electronic structure and optical properties of N-doped [Formula: see text] with different N impurity concentrations were calculated by density function theory within GGA[Formula: see text]+[Formula: see text]U method. The crystal distortion, impurity formation energy, band gap, band width and optical parameter of N-doped [Formula: see text] are closely related with N impurity concentration. Based on the calculated results, there are three new impurity energy levels emerging in the band gap of N-doped [Formula: see text], which determine the electronic structure and optical properties. The variations of optical properties induced by N doping are predominately determined by the unsaturated impurity states, which are more obvious at higher N impurity concentration. In addition, all the doping effects of N in both [Formula: see text]-quartz [Formula: see text] and [Formula: see text]-quartz [Formula: see text] are very similar. According to these findings, one could understand the relationship between nitrogen concentration and optical parameter of [Formula: see text] materials, and design new optoelectrionic Si–O–N compounds.

The title compound, C22H22N2O2S, shows remarkable activity against HIV-1. The benzoyl and benzyl rings form dihedral angles of 85.7 (2) and 77.4 (3)°, respectively, with the pyrimidine ring. The dihedral angle between the two phenyl rings is 19.3 (3)°. Intra­molecular C—H⋯N and C—H⋯O hydrogen bonds stabilize the mol­ecular structure. Centrosymmetrically related mol­ecules are linked by N—H⋯O hydrogen bonds into a dimer. In addition, inter­molecular C—H⋯O hydrogen bonds are observed

The title compound, C19H18N2O3S, shows favourable activity against HIV-1. The phenyl ring is twisted with respect to the pyrimidine ring by 61.56 (9)°. Inter­molecular N—H⋯O and C—H⋯O hydrogen bonding links the mol­ecules into a supra­molecular chain structure and stabilizes the crystal structure of the compound.