Wei-Shan Yu

Spectroscopy and dynamics of excited-state intramolecular proton-transfer reaction in 5-hydroxyflavone

Abstract Spectroscopy and dynamics of excited-state intramolecular proton-transfer (ESIPT) in 5-hydroxyflavone (5HF) have been investigated. In cyclohexane dual fluorescence maxima at ∼420 and 700 nm were observed. The time scale for both proton and deuterium transfer in the excited state cannot be resolved under the response time of ca. 160 fs of our femtosecond fluorescence upconversion system. Following ESIPT the excited keto-tautomer undergoes an unusually fast relaxation rate of ∼1.2 ps −1 . Fast internal conversion is concluded to play a major role to account for the dominant radiationless deactivation.

Studies of the triplet state of the proton-transfer tautomer in salicylaldehydes

Abstract The spectroscopy and dynamics of the low-lying triplet state of the proton-transfer tautomer in salicylaldehydes have been studied via internal heavy-atom effects coupled with a sensitive near-IR detecting system. For 3,5-diiodosalicylaldehyde a weak proton-transfer keto-tautomer phosphorescence was resolved with a maximum at 710 nm ( τ p ∼1.8 μs , Φ obs ∼5.23×10 −4 ) in a 77 K methylcyclohexane glass. The results, in combination with the time-resolved thermal lensing experiment, further deduced the triplet-state population yield and radiative decay rate to be 0.20 (298 K) and 3.12×10 2 s −1 , respectively. Consequently, the energetics and dynamics of the triplet states during a proton transfer cycle are discussed in detail.

Syntheses and remarkable photophysical properties of 5-(2-pyridyl) pyrazolate boron complexes; photoinduced electron transfer

A new series of pyridyl pyrazolate boron complexes 2a-e have been synthesized, in which 2a-c exhibit remarkable dual fluorescence properties due to the photoinduced electron transfer reaction.

Photodissociation of I2 in solution: the observation of solvent-dependent near-infrared emission associated with I()–solvent interaction

Abstract The photolysis of molecular iodine in solution phase has been investigated by Fourier transform techniques coupled with an ultrasensitive near-infrared detecting system. The spectral features and relaxation dynamics of the resulting 1200–1600 nm emission revealed strong solvent dependence. Detailed analyses conclude that the emitting species are attributed to the iodine atom ( 2 P 1/2 → 2 P 3/2 ) magnetic dipole transition in the near infrared perturbed by iodine atom–solvent complexes.