title: Spectroscopic Studies of Dual Fluorescence in 2-((4-Fluorophenyl)amino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole.
abstract: The paper presents results of fluorescence analysis of ionic and nonionic 2-((4-fluorophenyl)amino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT) in monocrystals and solutions. We found a single fluorescence band in the case of FABT crystals grown in methanol and dual fluorescence for FABT crystals grown in an aqueous environment. The effect of dual fluorescence was preserved for FABT dissolved in aqueous solutions with pH ranging from 7.5 to 1. In contrast, FABT dissolved in methanol exhibited a single fluorescence band. The dual fluorescence effect is associated with conformational changes in the FABT molecule, which can be induced by aggregation effects. On the basis of crystallographic data, two types of FABT crystal molecule conformations were distinguished. In methanol, FABT molecules are in conformation "S" (the -OH group from the resorcyl ring oriented toward the sulfur atom from the 1,3,4-thiadiazole ring), which a gives single fluorescence band. In water, FABT in conformation "N" (the -OH group from the resorcyl ring oriented toward the nitrogen atom from the 1,3,4-thiadiazole ring due to 180° rotation) has two fluorescence bands. This significant finding implies the possibility of performing a rapid analysis of conformational changes in FABT molecules using fluorescence spectroscopy both in solutions and in biological samples.
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Matwijczuk
authors.forename: Daniel
authors.initials: D
authors.lastname: Kamiński
authors.affiliation: Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology of the Jagiellonian University , 31-007 Kraków, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Górecki
authors.affiliation: Chair and Department of Pharmacognosy with Medicinal Plant Unit, Medical University of Lublin , 1 Chodzki Str., 20-093 Lublin, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Ludwiczuk
authors.forename: Andrzej
authors.initials: A
authors.lastname: Niewiadomy
authors.affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , 87-100 Toruń, Poland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Maćkowski
authors.affiliation: Department of Cell Biology, Institute of Biology, Maria Curie-Skłodowska University , 20-033 Lublin, Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Gagoś
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D015394:Molecular Structure; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013844:Thiazoles / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: C520297:2-(4-fluorophenylamino)-5-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole; D005456:Fluorescent Dyes; D013844:Thiazoles