engleski

Benzimidazole acrylonitriles as multifunctional push-pull chromophores: spectral characterisation, protonation equilibria and nanoaggregation in aqueous solutions

Heterocyclic donor-π-acceptor molecular systems based on an N, N-dimethylamino phenylacrylonitrile benzimidazole skeleton have been designed and characterised. The benzimidazole moiety introduces a broad spectrum of useful multifunctional properties to the system including electron accepting ability, biocompatibility and pH sensitity. 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 pKa values. It is noticed that compound 3 forms nanoaggregates in aqueous solutions with aggregation-induced emission (AIE) at 600 nm. 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, pKa values and aggregation effects have been determined. Potential applications of the molecules are proposed based on their pH sensitivity and AIE properties.

push-pull chromophores ; benzimidazole ; aggregation induced emission (AIE) ; pH sensitivity ; prototropic equlibrium

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