title: The fluorescence studies of the sol-gel transition by styrylpyridine derivative.
abstract: The gelation process of tetraethylorthosilanes in acid environment was monitored with the trans-4-(p-N,N-dimethylaminostyryl)-N-vinylbenzylopyridinium chloride (vbDMASP) fluorescent probe. The fluorescence steady-state and anisotropy measurements of material during sol-gel transition are reported. The results are compared with fluorescence studies of the probe in a modeled viscous system of water-glycerol mixtures. A strong increase of anisotropy, from 0.1 to 0.9, with gelation time as well with wavelength, was observed. Although the increase of anisotropy with wavelength is due to specificity of the compounds exhibiting charge transfer properties, the increase of the anisotropy with gelation time is due to an increase of microviscosity. On this basis, suitability of the applied fluorophore in recording of viscosity changes during sol-gel transition is discussed. The molecular structure of vbDMASP in the excited states in dependence on environmental polarity was optimized using the HyperChem and Amsol program. The dynamics of torsional angle C35-C34-N31-C28 of the multichromophore dye in correlation with micropolarity and microviscosity of the network formation during the sol-gel transition is discussed.
authors.affiliation: Institute of General Food Chemistry, Technical University of Łódź, ul. Stefanowskiego 4/10, Łódź 90-924, Poland. emiller@snack.p.lodz.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Miller
authors.forename: Barbara
authors.initials: B
authors.lastname: Wandelt
authors.forename: Stanisław
authors.initials: S
authors.lastname: Wysocki
authors.forename: Donata
authors.initials: D
authors.lastname: Jóźwik
authors.forename: Alina
authors.initials: A
authors.lastname: Mielniczak
mesh_terms: D000814:Aniline Compounds / Q000032:analysis / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000032:analysis / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry*; D044085:Microfluidics / Q000379:methods*; D008968:Molecular Conformation; D044367:Phase Transition; D011726:Pyridinium Compounds / Q000032:analysis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: C500828:4-(4-N,N-dimethylaminostyryl)-N-vinylbenzylopyridinium chloride; D000814:Aniline Compounds; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D014867:Water; D005990:Glycerol