Reversible and Turn-On Fluorescence Detection of Phosphate in Aqueous Solution and Living Cell Imaging by Supramolecular Metallacycles with AIE-Active Ligands

Abstract

Luminescent supramolecular metallacycles have attracted great interest as a new promising class of sensing substrates. In this work, two tetraphenylethene (TPE)-based diimidazole and dipyrazole ligands with the aggregation-induced emission (AIE) feature were designed for the construction of supramolecular tetragonal metallacycles 1–4 with two 90° mononuclear [(bpy)M]2+ or dinuclear [(bpy)2M2]4+ acceptors (bpy = 2,2′-dipyridine; M = Pd, Pt), in which the fluorescence can be quenched to an “off” state due to the ligand-to-metal charge transfer (LMCT). Metallacycle 1 was utilized as a fluorescence sensor for phosphate (PO4 3–) detection in aqueous solution by means of disassembly, leading to the release of the ligand. Additionally, the metallacycle can be regenerated through self-assembly via the introduction of Pd(II) acceptors. PO4 3– was detected using TPE-based metallacycles over a wide concentration range, with a detection limit as low as 2.1 × 10–8 M. Furthermore, sensor 1 also presented the semiquantitative visual detection ability for PO4 3– in the test paper mode via fluorescence changes. The aforementioned studies not only enhance the current research on fluorescent materials but also offer a strategy for the creation of stimuli-responsive supramolecular coordination complexes.

Chaotropic anion induced self-assembly of naphthalimide–glutathione nanohybrids: selective recognition of bisulphate anions in aqueous medium

“…Literature reports revealed that various types of promotors have been used in order to induce the self-assembly of organic-organic nanohybrids. [13][14][15][16][17][18][19][20][21][22][23] In particular extensive research has been carried out on anion induced selfassemblies of the peptide-based materials. Therefore, keeping in mind the importance of anions as promotors, we have analysed the effect of anions on fluorescence profiles of developed nanohybrids.…”

“…This AIEE mechanism has potential applications in chemical sensing, photonic devices, bio-sensing, bio-imaging and light harvesting. 20–22…”

“…This AIEE mechanism has potential applications in chemical sensing, photonic devices, bio-sensing, bio-imaging and light harvesting. [20][21][22] Nano-hybrids that exhibit various applications in chemical and environmental processes have been developed. [23][24][25] These nanohybrids are of great importance due to their large surface area, high volume ratio and water solubility.…”