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Novel bithienyl-benzimidazoles: one-pot synthesis and optical and solvatochromic studies
1, 2 , 3 , * 3
1  Physics Centers of the Universities of Minho and Porto, Campus de Gualtar, 4710-057 Braga, Portugal
2  Center of Chemistry, University of Minho, Campus de Gualtar 4710-057 Braga, Portugal
3  Centro de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal


Benzimidazoles are a group of heterocyclic compounds which have been applied in numerous aspects of science and technology. As a result of their interesting electronic and optical properties when incorporated in push-pull systems, benzimidazole derivatives found application as solvatochromic and fluorescent probes, chemosensors, organic light emitting diodes (OLEDs) and non-linear optical (NLO) chromophores.[1]

In the last decade our research group has reported experimental and theoretical results regarding the auxiliary donor/acceptor effect of electron deficient benz-X-azole derivatives in push-pull systems.[1b-c, 1e, 1g-i] In this work we describe the synthesis, UV-visible absorption, fluorescence and solvatochromic studies of a series of heterocyclic chromophores of the benzimidazole type. These new bithienyl-benzimidazoles were synthesised in good to excellent yields, by metal-free one-step reaction of o-nitroanilines in the presence of formyl-bithiophenes, via a reductive cyclization, and their optical and solvatochromic properties were evaluated in solvents of different character.


  1. (a) Esteves, C. I. C.; Batista, R. M. F.; Raposo, M. M. M.; Costa, S. P. G. Dyes Pigments 2016, 135, 134-142; (b) Baptista, R. M. F.; Isakov, D.; Raposo, M. M. M.; Belsley, M.; Bdikin, I.; Kholkin, A. L.; Costa, S. P. G.; Gomes, E. D. J. Nanopart. Res. 2014, 16 (7); (c) Garcia-Amorós, J.; Reig, M.; Castro, M. C. R.; Cuadrado, A.; Raposo, M. M. M.; Velasco, D. Chem. Commun. 2014, 50 (51), 6704-6706; (d) Pina, J.; Seixas de Melo, J. S.; Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. J. Org. Chem. 2013, 78 (22), 11389-11395; (e) Garcia-Amorós, J.; Castro, M. C. R.; Coelho, P.; Raposo, M. M. M.; Velasco, D. Chem. Commun. 2013, 49 (97), 11427-11429; (f) Batista, R. M. F.; Ferreira, R. C. M.; Raposo, M. M. M.; Costa, S. P. G. Tetrahedron 2012, 68 (36), 7322-7330; (g) Coelho, P. J.; Castro, M. C. R.; Fonseca, A. M. C.; Raposo, M. M. M. Dyes Pigments 2012, 92 (1), 745-748; (h) Raposo, M. M. M.; Castro, M. C. R.; Belsley, M.; Fonseca, A. M. C. Dyes Pigments 2011, 91 (3), 454-465; (i) Batista, R. M. F.; Costa, S. P. G.; Belsley, M.; Raposo, M. M. M. Tetrahedron 2007, 63 (39), 9842-9849.


Thanks are due to Fundação para a Ciência e Tecnologia (Portugal) for financial support through project FEDER-COMPETE for financial support through the CQ/UM PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302) and a post-doctoral grant to R.M.F. Batista (SFRH/BPD/79333/2011). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network, and was purchased with funds from POCI2010 (FEDER) and FCT.

Keywords: Bithiophenes; Benzimidazoles ; UV-visible spectroscopy; Solvatochromism ; Fluorescence