Salt effect on the ultrafast proton transfer in niosome.
Excited state proton transfer (ESPT) of pyranine (8-hydroxypyranine-1,3,6-trisulfonate, HPTS) in a niosome is studied by fluorescence correlation spectroscopy (FCS) and femtosecond up-conversion. The niosome consists of a neutral surfactant triton X-100 (TX-100) and cholesterol. FCS studies suggest that in the presence of niosome almost all of the HPTS is transferred to the niosome and the amount of free HPTS present in bulk water is negligible. The time constant of initial proton transfer (τ(PT)) in niosome (40 ps) is ∼8 times slower than that (5 ps) in bulk water, while the time constants of recombination (τ(rec)) and dissociation (τ(diss)) are ∼4 times and ∼1.5 times slower in niosome, respectively. On addition of NaCl, the rate of ESPT is markedly retarded both in free water and in niosome. In the niosome, τ(PT) slows down to 80 ps in 1 M NaCl and 225 ps in 4 M NaCl.
Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Tridib
T
Mondal
Shirsendu
S
Ghosh
Atanu Kumar
AK
Das
Amit Kumar
AK
Mandal
Kankan
K
Bhattacharyya
D001190:Arylsulfonates / Q000737:chemistry; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry*; D015394:Molecular Structure; D011522:Protons; D012965:Sodium Chloride / Q000737:chemistry; D014867:Water / Q000737:chemistry
D001190:Arylsulfonates; D008081:Liposomes; D011522:Protons; D014867:Water; D012965:Sodium Chloride; C005047:pyranine