Indeno–furan based colorimetric and on–off fluorescent pH sensors

•Two novel indeno–furan derivatives have been synthesized.•pH dependent absorption and emission properties of these sensors were investigated.•Both the sensors 3a and 3b showed visible color change also.

In this study, pH on–off fluorescent chemosensors based on indeno–furan derivatives have been designed, synthesized and characterized. The designed sensors were based on the change in structure of phenazine/ quinoxaline unit and keeping indeno–furan as common unit. These compounds exhibit pH dependent on/off fluorescence and thus act as fluorescent pH sensors. The change in fluorescence of 3a and 3b is reversible within the wide pH range of 2–11. The color change of these sensors could also be detected by naked eyes thus making them promising candidates as colorimetric pH indicators also.

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