Fluorescent indicators of metal ions based on dipyrromethene platform

This review highlights recent advances in new high sensitive and selective fluorescent chemosensors for metal ions based on the dipyrromethene platform with the advantages of bright color, significant fluorescence changes and simple structural functionalization. The most interesting results from studies on cationic sensors' structure and properties in organic, aqueous-organic, physiological media, and in cells are presented. The review includes a description of the main characteristics of fluorescent sensors which have been recently synthesized for a number of alkali, alkaline earth and mainly transition metal cations on the basis of open-chain oligopyrrole ligands such as dipyrromethenes, tripyrrins (prodigiosintype), bis(dipyrromethene)s and boron(III) dipyrromethene (BODIPY). It was shown that the hybrid molecules, built from BODIPY and other similar chelating ligands, are effective fluorescent chemosensors on various metal cations, depending on the receptor fragment' nature, but are very difficult to obtain. Dipyrromethene ligands and their tri- and tetrapyrrole analogues combine the functions of both a chelating agent and a selective fluorescent sensor of zinc ions compared to other metal ions. Dipyrrornethenes and their derivatives demonstrate weak fluorescence whereas metal coordination improves the systems rigidity, which results in fluorescence enhancement. The action of dipyrromethene sensors based on fluorescence buildup effects upon complexation (chelation enhanced fluorescence, CHEF). Fluorescent response of dipyrromethene dye complexation reactions with metal ions can be observed with naked eye. Moreover, the sensors with emissions in the IR region (>650 nm) may be suitable for biochemical applications. (C) 2016 Published by Elsevier Ltd.