title: Photophysical characterization of a benzo-fused analogue of Brooker's merocyanine: solvent polarity and pH effects.
abstract: The photophysical properties of 4-[2-(6-hydroxy-2-naphthalenyl)-ethenyl]-1-methyl-pyridinium (HNEP(+)) and its deprotonated form (NEP), a benzofused derivative of Brooker's merocyanine (BM), were investigated through a combined spectroscopic and computational approach. Despite their structural similarities and similar pK(a) values, HNEP(+)/NEP and BMH(+)/BM differ in the extent of charge delocalization in the ground and excited states. NEP exhibits the spectral characteristics of a charge transfer species in solvents in which BM exists in a charge-delocalized quinoid; however, quantum chemical calculations show that the CT absorption of NEP is not necessarily a consequence of the zwitterionic character. HNEP(+) displays larger Stokes shifts than BMH(+), and NEP demonstrates enhanced solvatochromism relative to BM as a consequence of benzofusion.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States.
authors.forename: Edward
authors.initials: E
authors.lastname: Adjaye-Mensah
authors.forename: Walter G
authors.initials: WG
authors.lastname: Gonzalez
authors.forename: Jaroslava
authors.initials: J
authors.lastname: Miksovska
authors.forename: James N
authors.initials: JN
authors.lastname: Wilson
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008968:Molecular Conformation; D011522:Protons; D011725:Pyridines / Q000737:chemistry*; D011744:Pyrimidinones / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D004396:Coloring Agents; D011522:Protons; D011725:Pyridines; D011744:Pyrimidinones; D012997:Solvents; C003954:merocyanine dye