title: Benzimidazole acrylonitriles as multifunctional push-pull chromophores: Spectral characterisation, protonation equilibria and nanoaggregation in aqueous solutions.
abstract: Heterocyclic donor-π-acceptor molecular systems based on an N,N-dimethylamino phenylacrylonitrile benzimidazole skeleton have been characterised and are proposed for potential use in sensing applications. The benzimidazole moiety introduces a broad spectrum of useful multifunctional properties to the system including electron accepting ability, pH sensitivity and compatibility with biomolecules. The photophysical characterisation of the prototropic forms of these chromophores has been carried out in both solution and on immobilisation in polymer films. The experimental results are further supported by computational determination of pKavalues. It is noticed that compound 3 forms nanoaggregates in aqueous solutions with aggregation-induced emission (AIE) at 600nm. All the systems demonstrate spectral pH sensitivity in acidic media which shifts towards near-neutral values upon immobilisation in polymer films or upon aggregation in an aqueous environment (compound 3). The structure-property relationships of these functional chromophores, involving their spectral characteristics, acid-base equilibria, pKavalues and aggregation effects have been determined. Potential applications of the molecules as pH and biomolecular sensors are proposed based on their pH sensitivity and AIE properties.
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, HR 10000 Zagreb, Croatia.
authors.forename: Ema
authors.initials: E
authors.lastname: Horak
authors.affiliation: Computational Organic Chemistry and Biochemistry Group, Ruđer Bošković Institute, Bijenička cesta 54, HR 10000 Zagreb, Croatia.
authors.forename: Robert
authors.initials: R
authors.lastname: Vianello
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR 10000 Zagreb, Croatia.
authors.forename: Marijana
authors.initials: M
authors.lastname: Hranjec
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, HR 10000 Zagreb, Croatia.
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Krištafor
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, HR 10000 Zagreb, Croatia.
authors.forename: Grace Karminski
authors.initials: GK
authors.lastname: Zamola
authors.affiliation: Department of General and Inorganic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, HR 10000 Zagreb, Croatia. Electronic address: ivana.murkovic@fkit.hr.
authors.forename: Ivana Murković
authors.initials: IM
authors.lastname: Steinberg
mesh_terms: D000181:Acrylonitrile / Q000737:chemistry*; D000818:Animals; D001562:Benzimidazoles / Q000138:chemical synthesis / Q000737:chemistry*; D002417:Cattle; D004247:DNA / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011108:Polymers / Q000737:chemistry; D011522:Protons; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry*
chemical_list: D001562:Benzimidazoles; D005456:Fluorescent Dyes; D011108:Polymers; D011522:Protons; D012996:Solutions; D014867:Water; D004247:DNA; C427203:calf thymus DNA; C031000:benzimidazole; D000181:Acrylonitrile
keywords: Aggregation induced emission (AIE); Benzimidazole; Prototropic equilibrium; Push-pull chromophores; pH sensitivity