Photocatalytic C-H activation for C-C/C&z.dbd;N/C-S bond formation over CdS: effect of morphological regulation and S vacancies

The construction of C-X (X = C, N, S) bonds through C-H activation is one of the most challenging, important and rapidly developing fields in recent years. Herein, CdS with different morphologies (nanorods, nanospheres, nanosheets) was prepared by a thermal solvent method, and CdS enriched with S vacancies was constructed through simple calcination. The as-prepared heterogeneous CdS catalytic materials were utilized to fabricate C-C, C&z.dbd;N and CS bonds for the manufacture of drug intermediates or other value-added products through high bond energy, low polarity and strong inertia CH bond activation. For example, the direct activation of sp 3 CH chemical bonds of tetrahydrofuran (THF) to form THF free radical and the free radical addition with olefins/alkynes could be achieved with various CdS catalytic materials without a base additive and oxidant. The CdS morphology improved the photocatalytic performance through the effective photogenerated carrier separation and transformation enhancement caused by the formation of hexagonal-phase CdS along with a certain degree of lattice distortion induced polarization dipole moment and internal polarization electric field. Furthermore, the S-vacancy-enriched CdS nanorods provided more active sites for THF capture and tetrahydrofuran free radical generation, so that the THF sp 3 C-H direct activation to construct C-C bonds became more feasible. DMF and toluene sp 3 C-H could also be activated to form C-C bonds; benzylamine sp 3 C-H could be activated to construct C&z.dbd;N bonds accompanied by H 2 generation; benzyl mercaptan S-H bonds and phenylacetylene/styrene C-H bonds could be activated to build C-S bonds; and benzene/toluene C-H bonds could be activated in the presence of CO 2 to produce carboxylic acid. Compared with the method requiring a stoichiometric oxidant in previous studies, the C-H activation of THF and the construction of other inert chemical structures could be mildly realized over S-vacancy-enriched hexagonal CdS nanorods. CdS catalytic materials were utilized to fabricate C-C, C&z.dbd;N and C-S bonds for drug intermediates or other value-added products through the high bond energy, low polarity and strong inertia C-H bonds activation.