title: Pressure effect on the nonradiative process of thioflavin-T.
abstract: Time-resolved emission techniques were employed to study the nonradiative process of thioflavin-T (ThT) in 1-propanol, 1-butanol, and 1-pentanol as a function of the hydrostatic pressure. Elevated hydrostatic pressure increases the alcohol viscosity, which in turn strongly influences the nonradiative rate of ThT. A diamond-anvil cell was used to increase the pressure up to 2.4 GPa. We found that the nonradiative rate constant, k(nr), decreases with pressure. We further found a remarkable linear correlation between a decrease in k(nr) (increase in the nonradiative lifetime, τ(nr)) and an increase in the solvent viscosity. The viscosity was varied by a factor of 1000 and k(nr) was measured at high pressures, at which the nonradiative rate constant of the molecules decreased from (7 ps)(-1) to (13 ns)(-1), (13 ps)(-1) to (17 ns)(-1) and (17 ps)(-1) to (15 ns)(-1) for 1-propanol, 1-butanol, and 1-pentanol, respectively. The viscosity-dependence of k(nr) is explained by the excited-state rotation rate of the two-ring systems, with respect to each other.
authors.affiliation: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Nadav
authors.initials: N
authors.lastname: Amdursky
authors.forename: Rinat
authors.initials: R
authors.lastname: Gepshtein
authors.forename: Yuval
authors.initials: Y
authors.lastname: Erez
authors.forename: Naum
authors.initials: N
authors.lastname: Koifman
authors.forename: Dan
authors.initials: D
authors.lastname: Huppert
mesh_terms: D020001:1-Butanol / Q000737:chemistry; D000433:1-Propanol / Q000737:chemistry; D052160:Benzothiazoles; D005453:Fluorescence; D015394:Molecular Structure; D000439:Pentanols / Q000737:chemistry; D011312:Pressure; D013844:Thiazoles / Q000737:chemistry*; D013997:Time Factors; D014783:Viscosity
chemical_list: D052160:Benzothiazoles; D000439:Pentanols; D013844:Thiazoles; C009462:thioflavin T; D020001:1-Butanol; D000433:1-Propanol; C024999:n-pentanol