title: Bright, fluorescent dyes based on imidazo[1,2-a]pyridines that are capable of two-photon absorption.
abstract: A library of imidazo[1,2-a]pyridines was synthesized by using the Gevorgyan method and their linear and non-linear optical properties were studied. Derivatives that contained both electron-donating and electron-withdrawing groups at the 2 position were comprehensively investigated. Their emission quantum yield ranged between 0.2-0.7 and it was shown to depend on the substitution pattern, most notably that on the phenyl ring. Electron-donating substituents improved the luminescence performance of these compounds, whereas electron-withdrawing substituents led to a more erratic behavior. Substitution on the six-membered ring had less effect on the fluorescence properties. Extension of the delocalization increased the luminescence quantum yield. A new quadrupolar system was designed that contained two imidazo[1,2-a]pyridine units on its periphery and a 1,4-dicyanobenzene unit at its center. This system exhibited a large Stokes-shifted luminescence that was affected by the polarity and rigidity of the solvent, which was ascribed to emission from an excited state with strong charge-transfer character. This quadrupolar feature also led to an acceptable two-photon absorption response in the NIR region.
authors.affiliation: Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, 00-664 Warsaw, Poland.
authors.forename: Dikhi
authors.initials: D
authors.lastname: Firmansyah
authors.forename: Adina I
authors.initials: AI
authors.lastname: Ciuciu
authors.forename: Vincent
authors.initials: V
authors.lastname: Hugues
authors.forename: Mireille
authors.initials: M
authors.lastname: Blanchard-Desce
authors.forename: Lucia
authors.initials: L
authors.lastname: Flamigni
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Gryko
mesh_terms: D000042:Absorption; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D015394:Molecular Structure; D017785:Photons; D011725:Pyridines / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D005456:Fluorescent Dyes; D007093:Imidazoles; D011725:Pyridines