title: Synthesis, X-ray and Fluorescence Characteristics of Pyrimido[5,4-e]thiazolo[3,2-a]pyrimidine as a Novel Heterocyclic System.
abstract: Derivatives of a new heterocyclic system, pyrimido[5,4-e]thiazolo[3,2-a]pyrimidine 3, were prepared by sequential treatment of ethyl 4-chloro-2-(methylthio)pyrimidine-5-carboxylate 1 with 4,5-dihydrothiazol-2-amine 2 and various secondary amines. Single crystal X-ray analysis confirmed the structure of the regioisomer 3. The photophysical characterization of these new compounds was performed by UV/VIS absorption and fluorescence emission spectroscopy. Out of six derivatives studied, only four products 4a-d showed relatively strong fluorescence intensity. The relevant photophysical parameters for all derivatives in this series, including quantum yields and Stokes shifts for the best fluorophores are given.
authors.affiliation: Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Ebrahimpour
authors.affiliation: Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran. mbakavoli@um.ac.ir.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Bakavoli
authors.affiliation: Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Shiri
authors.affiliation: Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Seyedi
authors.affiliation: Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 91775-1436, Iran.
authors.forename: Tayebe
authors.initials: T
authors.lastname: Asghari
authors.affiliation: Department of Chemistry, Tulane University, New Orleans, LA, 70118, USA.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Mague
keywords: Fluorescence spectroscopy; Heterocyclization; Pyrimidothiazolopyrimidine; X-ray