Synthesis and spectroscopic studies of highly fluorescent, solvatochromic diastereomers with differentially stacked bithiophene-substituted quinoxaline rings

TETRAHEDRON

卷:73

Article

Ciufo, Ryan A.¹  Kreinbihl, John J.¹  Johnson, Sarah R.¹  Nadeau, Jocelyn M.¹ 

[1] Marist Coll, Dept Chem Biochem & Phys, 3399 North Rd, Poughkeepsie, NY 12601 USA

关键词: Quinoxaline;    Bithiophene;    Pi overlap;    Intramolecular excimer;    Charge transfer;    Solvatochromic;   

DOI  :  10.1016/j.tet.2016.11.044

来源: Elsevier

【 摘 要 】

Diastereomeric C-shaped molecules containing closely stacked bithiophene-substituted quinoxaline rings were synthesized and characterized by NMR, UV vis absorption, and fluorescence spectroscopy. The unique geometry of each diastereomer resulted in different degrees of it-overlap between the bithiophene-substituted quinoxaline ring chromophores, modulating their spectroscopic properties. The donor-acceptor nature of this chromophore gave rise to its positive solvatochromism. H-1 NMR and UV vis absorption spectroscopy confirmed the existence of pi-pi interactions in the ground state between the quinoxaline rings in both molecules but between the bithiophene rings only in the syn isomer. They exhibited significant emission maxima bathochromic shifts, a strong, positive solvatochromism, increased band broadening, and larger Stokes shifts when compared to a compound with an unstacked chromophore. Additionally, the syn isomer consistently showed lambda(max,em) value red-shifts and larger band broadening and Stokes shifts compared to the anti isomer due to the greater pi-overlap in the syn isomer. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

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