Fluorescent Chemosensors Based on Polyamine Ligands: A Review

Abstract

Polyamine ligands are water-soluble receptors that are able to coordinate, depending on their protonation degree, either metal ions, anionic, or neutral species. Furthermore, the presence of fluorescent signaling units allows an immediate visual response/signal. For these reasons, they can find applications in a wide variety of fields, mainly those where aqueous media is necessary, such as biological studies, wastewater analysis, soil contamination, etc. This review provides an overview of the recent developments in the research of chemosensors based on polyamine ligands functionalized with fluorescent signaling units. The discussion focuses on the design, synthesis, and physicochemical properties of this type of fluorescent chemosensors in order to analyze the applications associated to the sensing of metal ions, anions, and neutral molecules of environmental and/or biological interest. To facilitate a quick access and overview of all the chemosensors covered in this review, a summary table of the chemosensor structures and analytes, with all the corresponding references, is also presented.

Converting pH probes into “turn-on” fluorescent receptors for anions

“…In 2006 Garćia-Espańa observed the fluorescence enhancement with macrocyclic receptor 2 and citrate at pH 6. 28 The macrocycle design is similar to one reported by Czarnik. In both cases, the fluorescence of receptors are pH- and anion-sensitive, which precludes the supramolecular shift of the p K a s of amine groups in the presence of anions.…”

A novel 2,6-bis(benzoxazolyl)phenol macrocyclic chemosensor with enhanced fluorophore properties by photoinduced intramolecular proton transfer

“…[1][2][3] Among the systems useful for this purpose, chemosensors based on polyazamacrocycles are of particular relevance. [4][5][6] These molecules contain a macrocyclic polyamine capable of binding an analyte and a fluorophore acting as the signaling unit, which could be linked to the macrocyclic scaffold as a side arm or integrated into the macrocyclic structure; the interaction of the analyte with the receptor leads to a change in the emission properties of the fluorophore (namely, signal transduction) constituting the output response of the system. 7 In the design of fluorescence sensors, particular attention must be devoted to the comprehension of the signal transduction mechanism, which is regulated by specific physical-chemical processes occurring when a ligand interacts with an analyte.…”

Sequential Nitrile Amidination–Reduction as a Straightforward Procedure to Selective Linear Polyamine Preparation

“…11−14 Such short, linear polyamines, which are mostly made by the linear combination of a small number (1 to 5) of ethylenimine and/or propyleneimine units, can provide effective antiviral treatments, including that for the recent SARS-CoV. 15 These and other technical applications (ion scavengers, 16 self-healing polymers, 17,18 molecular sensors, 19 among others) of linear, short-chain polyamines make these structures interesting targets from a synthetic point of view. However, despite the apparent structural simplicity of these molecules, their syntheses remain far from easy.…”

“…These and other technical applications (ion scavengers, self-healing polymers, , molecular sensors, among others) of linear, short-chain polyamines make these structures interesting targets from a synthetic point of view. However, despite the apparent structural simplicity of these molecules, their syntheses remain far from easy.…”