title: Anion Binding-Induced White Light Emission using a Water-Tolerant Fluorescent Molecular Tweezer.
abstract: A novel fluorescent molecular tweezer (FMT), built on the pyridine-2,6-bis-carboxamide framework, has been developed that, in presence of a red emitter, gives rise to white light emission in response to the addition of H2PO4-anions. The FMT incorporates two pyrene moieties as fluorescent reporter units and a strategically placed amine residue that imparts pH sensitivity to the fluorescence and offers additional electrostatic/hydrogen-bonding interactions to the anions. As a result, this FMT selectively binds monoanionic tetrahedral oxyanions such as H2PO4-and HSO4-that contain hydrogen bond donors and acceptors, and can sense their presence in aqueous acetonitrile through changes in fluorescence. Anion binding results in excimer formation by the pyrenes and a bluish-green emission from the FMT. Both amide and amine residues of the FMT interact with these anions. The binding stoichiometry with H2PO4-and HSO4-was found to be 1:1 and affinity of the FMT for these anions is of the order of 104m-1. The limit of detection for H2PO4-was found to be 13 nm. Addition of a perylene monoimide-based red emitter gives rise to panchromatic emission perceived as white light.
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Indore Bypass Road, Bhauri, Bhopal, 462066, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Indore Bypass Road, Bhauri, Bhopal, 462066, India. asri@iiserb.ac.in.
authors.forename: Aasheesh
authors.initials: A
authors.lastname: Srivastava
keywords: anion sensing; electron transfer; excimer formation; fluorescence; self-assembly