Intramolecular charge transfer supercritical fluids

In another investigation, picosecond absorption studies were conducted on TPE singlet excited state in supercritical fluids. Studies were also carried out on ethyl-(Af,Af-dimethylamino)benzoate TICT (twisted intramolecular charge transfer) state for comparison with the TPE studies in supercritical fluids [62]. The decay rates of excited singlet of TPE were found to be correlatable with the solvent-induced changes. The results of this study indicated that the singlet excited state of TPE is twisted and is associated with a polar or zwitterionic character. 

Y-P Sun, TL Bowen, CE Bunker. Formation and decay of the ethyl p- N,N-diethylamino)benzoate twisted intramolecular charge-transfer state in the vapor phase, supercritical fluids, and room-temperature solutions. J Phys Chem 98 12486, 1994. 

O Kajimoto, K Yamasaki, K Houma. Intramolecular charge-transfer reactions studied in a supercritical fluid of varying densities and in a molecular beam. Faraday Disc Chem Soc 85 65, 1988. 

O Kajimoto, T Nayuki, T Kobayashi. Picosecond dynamics of the twisted intramolecular charge-transfer state formation of 4-(V,A-dimethylarnino)benxonitrile (DMABN) in supercritical fluid solvent. Chem Phys Lett 209 357, 1993. 

Y-P Sun, CE Bunker. Twisted intramolecular charge transfer of ethyl p-(N,N-diethylaminojbenzoate in the gas phase and in the low-density non-polar supercritical fluids, a quantitative spectral resolution using principal component analysis and self modeling. J Chem Soc, Chem Commun 5, 1994. 

Y-P Sun, G Beimett, KP Johnston, MA Fox. Quantitative resolution of dual fluorescence spectra in molecules forming twisted intramolecular charge-transfer states. Toward establishment of molecular probes for medium effects in supercritical fluids and mixtures. Anal Chem 64 1763, 1992. 

Steady-state fluorescence spectroscopy has also been used to study solvation processes in supercritical fluids. For example, Okada et al. (29) and Kajimoto and co-workers (30) studied intramolecular excited-state complexation (exciplex) and charge-transfer formation, respectively, in supercritical CHF3. In the latter studies, the observed spectral shift was more than expected based on the McRae theory (56,57), this was attributed to cluster formation. In other studies, Brennecke and Eckert (5,31,44,45) examined the fluorescence of pyrene in supercritical CO2, C2HSteady-state emission spectra were used to show density augmentation near the critical point. Additional studies investigated the formation of the pyrene excimer (i.e., the reaction of excited- and ground-state pyrene monomers to form the excited-state dimer). These authors concluded that the observance of the pyrene excimer in the supercritical fluid medium was a consequence of increased solute-solute interactions. 

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See also in sourсe #XX -- [ ]

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