title: Ultrafast excited state dynamics of trans-[4-(4'-dimethylaminostyryl)] pyridine N-oxide in solution: femtosecond fluorescence up-conversion and theoretical calculations.
abstract: The results of the steady-state and time-resolved fluorescence-spectroscopy measurements and DFT calculations for trans-[4-(4'-dimethylaminostyryl)] pyridine N-oxide (trans-DPO) in various solvents are presented. These results are similar to those reported in the literature for trans-4-(dimethylamino)-4'-cyanostilbene (DCS) where the S1 emissive state shows the charge-transfer (CT) nature. Alcohol solvents, however, have aroused our particular interest because hydrogen-bonded complexes are formed between them and the trans-DPO molecule. They demonstrate a stronger CT character of the lower lying excited state and a larger separation between the first and the second absorption band than in the free trans-DPO molecule. The different effects found in time-dependent femtosecond up-conversion (performed for several emission wavelengths in dioxane and methanol solution over the time range 0-40 ps) were assigned to the hydrogen bond assisted charge transfer process in trans-DPO in methanol, to the excited-state solvation dynamics and mainly to solvent relaxation of trans-DPO dissolved in dioxane and methanol.
authors.affiliation: Faculty of Chemistry, University of Wroclaw, Wrocław, Poland. anna.szemik@chem.uni.wroc.pl
authors.forename: Anna
authors.initials: A
authors.lastname: Szemik-Hojniak
authors.forename: Irena
authors.initials: I
authors.lastname: Deperasińska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Oberda
authors.forename: Yuval
authors.initials: Y
authors.lastname: Erez
authors.forename: Dan
authors.initials: D
authors.lastname: Huppert
authors.forename: Yakov P
authors.initials: YP
authors.lastname: Nizhnik
mesh_terms: D000438:Alcohols / Q000737:chemistry; D006860:Hydrogen Bonding; D007536:Isomerism; D008958:Models, Molecular; D009570:Nitriles / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013267:Stilbenes / Q000737:chemistry; D013343:Styrenes / Q000737:chemistry*; D013997:Time Factors
chemical_list: C116158:4-(dimethylamino)-4'-cyanostilbene; D000438:Alcohols; D009570:Nitriles; D011725:Pyridines; D012996:Solutions; D013267:Stilbenes; D013343:Styrenes; C585293:trans-(4-(4'-dimethylaminostyryl))pyridine N-oxide; C013229:pyridine N-oxide