An ultra-robust luminescent CAU-10 MOF acting as a fluorescent turn-off sensor for Cr2O72- in aqueous medium

For public health and environmental safety, the detection of heavily poisonous Cr2O72- ion from aqueous medium is a highly demanding task. A highly robust and reusable porous material can address this job. In this work, an aldehyde functionalized Al(III)-based luminescent metal-organic framework (MOF) denoted as CAU-10-CHO (1, CAU stands for Christian-Albrechts-University) was employed for the detection of toxic Cr2O72- ion in aqueous medium. The compound was synthesized solvothermally and thoroughly characterized. The desolvated compound showed ultra-fast, specific and sensitive detection behavior towards Cr2O72- in HEPES buffer (10 mM, pH = 7.4). Moreover, the material could retain its specificity for Cr2O72- even in co-existence of possibly disturbing anionic species. In addition, the material showed efficient sensing properties in wide pH range (2-12) without losing its structural integrity. Moreover, the material could be reusable up to 5 cycles. The material has the ability to detect Cr2O72- in real water specimens. Furthermore, MOF-coated paper test strips were utilized for the on-site fluorimetric detection of Cr2O72-. The limit of detection of the material for Cr2O72- was found to be 0.69 mu M. The mechanism of the detection event was also investigated in detail.