Benzimidazole-based polyheterocycles from ninhydrin: Synthesis, X-ray crystal structure and photophysical property

Ninhydrin was successfully employed to develop two different benzimidazole-embedded heterocyclic skeletons via reaction of arylated ninhydrin and o-phenylenediamine under acidic condition. While ninhydrin adduct of 2-iodophenol consumed two equivalent of o-phenylenediamine to furnish benzimidazole linked quinoxaline skeleton, under same reaction conditions corresponding 2-methoxynaphthalene adduct afforded benzimidazo[2,1-a]isoquinolinone framework. The hybrid heterocycles were identified as 2-(3-(2-(1H-benzo[d]imidazole-2-yl)phenyl)quinoxalin-2-yI)-6-iodophenol 3 and 6-hydroxy-6-(2-methoxynaphthalen-l-yl)benzo [4,5]imidazo[2,1-alisoquinolin-5(6H)-one 4 by IR, NMR and single crystal X-ray diffraction studies. Fluorescence measurements reveal that compound 3 and 4 display differential fluorescence behaviour, particularly towards the presence of Zn2+ ion. (C) 2018 Elsevier B.V. All rights reserved.