Preparation of polypseudorotaxanes composed of cyclodextrin and polymers in microspheres.

We prepared polypseudorotaxanes (PPRXs) composed of cyclodextrin (CyD) and polyethylene glycol (PEG) inside microspheres (MSs) by an emulsifying process using polypropylene glycol (PPG) that shows temperature-dependent hydrophilicity changes; PPG is hydrophobic at high temperatures but hydrophilic at low temperatures. An aqueous solution of CyD and PEG was dispersed as droplets in PPG at 60°C then cooled to 0°C to allow water of droplets to transfer into PPG. On removal of water in the droplets, CyD and PEG were left behind as a CyD/PEG PPRX inside the solid-state MSs.

Excited-state double-proton transfer in the 7-azaindole dimer in the gas phase. 3. Reaction mechanism studied by picosecond time-resolved REMPI spectroscopy.

The excited-state double-proton-transfer (ESDPT) reaction in the jet-cooled 7-azaindole dimer (7AI2) has been investigated with picosecond time-resolved resonance-enhanced multiphoton ionization spectroscopy. The observed decay profiles of 7AI2 by exciting the origin and the intermolecular stretch fundamental in the S1 state are well reproduced by single-exponential functions with time constants of 1.9 +/- 0.

Electronic spectra of hydrogen-bonded 2-fluoropyridine clusters with water in a supersonic free jet.

Fluorescence excitation, multiphoton ionization, and dispersed fluorescence spectra of bare and hydrogen-bonded 2-fluoropyridine with water were measured in a supersonic free jet. For bare 2-fluoropyridine, fluorescence quantum yield decrease in the higher vibronic levels was observed even under collision-free conditions. The inter-system crossing channel was probed experimentally by two color R2PI and found to be negligible.

Ultrafast excited-state dynamics in photochromic N-salicylideneaniline studied by femtosecond time-resolved REMPI spectroscopy.

Ultrafast processes in photoexcited N-salicylideneaniline have been investigated with femtosecond time-resolved resonance-enhanced multiphoton ionization spectroscopy. The ion signals via the S(1)(n,pi( *)) state of the enol form as well as the proton-transferred cis-keto form emerge within a few hundred femtoseconds after photoexcitation to the first S(1)(pi,pi( *)) state of the enol form. This reveals that two ultrafast processes, excited-state intramolecular proton transfer (ESIPT) reaction and an internal conversion (IC) to the S(1)(n,pi( *)) state, occur on a time scale less than a few hundred femtoseconds from the S(1)(pi,pi( *)) state of the enol form.