Orthogonal hydrogen and halogen bonding facilitate intermolecular charge transfer between barbaturic acid and molecular halogens over g-C 3 N 4 nanosheet: A comparative experimental and DFT calculations

Durable photogenerated Charge separation in nanomaterials is an essential parameter in semiconductors application. Here, we immobilized the orthogonal hydrogen bonding (HB) and halogen bonding (XB) stabilized complexes of barbaturic acid with molecular halogens (X 2 =I 2, Br 2, Cl 2, and F 2 ) on g-C 3 N 4 surface for the decreasing the photogenerated electron/hole recombination process. The BUX 2 /g-C 3 N 4 composite reveal lower band gap (2.65 eV) than the pristine g-C 3 N 4. Spectroscopic techniques such as UV–Vis, photoluminescence, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and energy dispersive X-ray fluorescence (EDXRF) were used to investigate the molecular complexes and BUX 2 /g-C 3 N 4 composites. Density Functional Theory calculations (rwb97xd/lanl2dz) were used to investigate the molecular interactions and explore the binding noncovalent forces. The cooperative orthogonal HB and XB stabilized the BUX 2 complexes in polar solvents. Noncovalent forces (vdW) were the dominant factors for the binding of BUX 2 on g-C 3 N 4 nanosheets. The quantative charge transfer from g-C 3 N 4 to BUX 2 increases in the order of I 2 > Br 2 > Cl 2 > F 2, which in accordance with the complexes stability.