1 research outputs found
Efficient Upconversion by Highly Water-Soluble Cationic Sensitizer and Emitter in Aqueous Solutions with DNA
Highly
water-soluble cationic palladium porphyrin as a sensitizer
and 9,10-bis(4-trimethylammoniumphenyl)anthracene as an emitter were
newly synthesized. They were shown to be bound and immobilized in
DNA double helix assembly from absorption, fluorescence, phosphorescence,
and circular dichroism spectra. Upon excitation at 532 nm in deaerated
aqueous solutions, they showed weak blue upconversion fluorescence,
the efficiency of which increased dramatically in the presence of
DNA. The threshold power density between the second-order and first-order
power dependence of upconversion fluorescence decreased to less than
a half upon addition of DNA. The emitter triplet lifetime estimated
from time dependences of upconversion fluorescence at low power ns
pulsed laser was found to considerably increase in the presence of
DNA. From these results, DNA was concluded to work effectively in
concentrating both sensitizer and emitter and in migrating excited
triplet states, resulting in efficient upconversion