Fluorescence enhancing and quenching of TiO2 by benzimidazole

2-(4-Fluorophenyl)-1-phenyl-1H-benzo[d]imidazole (FPPBI) has been synthesized and characterized by 1H NMR, 13C NMR, mass spectral and single crystal XRD studies. Absorption and fluorescence spectral studies have been employed to investigate the interaction of FPPBI with the TiO2 (A), TiO2 (H), TiO2 (P25) and TiO2 (R). The fluorescence of FPPBI is efficiently quenched by TiO2 (A), TiO2 (H) and TiO2 (P25) nanoparticles owing to charge injection from the excited singlet state of FPPBI to the conduction band of the TiO2 nanoparticles. Surprisingly TiO2 (R) enhances the fluorescence due to lowering of LUMO and HOMO levels of the FPPBI.