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Single phasic anatase titania with up to 10 mol % vanadium doping, having a particle size of about 12 nm, was synthesized by a sol-gel route and its photocatalytic behavior evaluated for the photo-oxidation of ethene using sunlight-type excitation. Incorporation of vanadia in the titania lattice was established using techniques like XRD, XPS, surface area analysis, TEM, DR-UV-visible spectroscopy, Raman spectroscopy, and FTIR. Vanadium doping led to a red shift in the UV-visible absorbance spectra compared to pristine titania, thus enhancing the absorption in the visible region. Synthesized nanotitania and vanadia-doped titania exhibit enhanced photocatalytic activity compared to the commercial bulk anatase TiO 2 , with maximum activity obtained for the 5 mol % vanadium-doped titania sample, which was attributed to an optimum concentration of V 4+ and V 5+ species. The role of these species in enhancement of catalytic activity and reaction mechanism has been discussed.

Interaction of bovine serum albumin (BSA) with two series of dipolar molecules having both rigid and flexible structures has been studied by monitoring the spectral and temporal behavior of the intramolecular charge transfer fluorescence of the systems. The binding sites of the molecular systems in BSA have been located with the help of docking studies. Three different sites of varying hydrophobicity have been identified where these molecules are located. Binding in the hydrophobic domains of BSA leads to a blue shift of the fluorescence spectra and an enhancement of fluorescence intensity and lifetime. This enhancement is found to be the largest for flexible systems in which internal motion serves as a nonradiative decay route. In the BSA-bound condition, some of the dipolar molecules exhibit not-so-common "dip-rise-dip" time-resolved fluorescence anisotropy profiles. It is shown that a large difference of the fluorescence lifetimes of the protein-bound and unbound molecules is one of the factors that contributes to this kind of anisotropy profiles. As internal motion is often responsible for the short fluorescence lifetime of the flexible dipolar molecules, a large increase in the fluorescence lifetime of these systems occurs if binding to BSA leads to disruption/prevention of this motion. It thus appears that it might be possible to obtain information on the prevention/disruption of nonradiative pathway on protein binding from the anisotropy profiles of the kind discussed above. However, since the present study reveals cases where a large change in fluorescence lifetime also occurs due to other reasons, one needs to be careful prior to making any conclusion.

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