Metallacycle-cored supramolecular assemblies with tunable fluorescence including white-light emission

Abstract

Control over the fluorescence of supramolecular assemblies is crucial for the development of chemosensors and light-emitting materials. Consequently, the postsynthetic modification of supramolecular structures via host-guest interactions has emerged as an efficient strategy in recent years that allows the facile tuning of the photophysical properties without requiring a tedious chemical synthesis. Herein, we used a phenanthrene-21-crown-7 (P21C7)-based 60° diplatinum(II) acceptor 8 in the construction of three exohedral P21C7 functionalized rhomboidal metallacycles 1-3 which display orange, cyan, and green emission colors, respectively. Although these colors originate from the dipyridyl precursors 10-12, containing triphenylamine-, tetraphenylethene-, and pyrene-based fluorophores, respectively, the metal-ligand coordination strongly influences their emission properties. The metallacycles were further linked into emissive supramolecular oligomers by the addition of a fluorescent bis-ammonium linker 4 that forms complementary host-guest interactions with the pendant P21C7 units. Notably, the final ensemble derived from a 1:1 mixture of 1 and 4 displays a concentration-dependent emission. At low concentration, i.e., <25 µM, it emits a blue color, whereas an orange emission was observed when the concentration exceeds >5 mM. Moreover, white-light emission was observed from the same sample at a concentration of 29 µM, representing a pathway to construct supramolecular assemblies with tunable fluorescence properties.

Molecular Engineering Approaches Towards All‐Organic White Light Emitting Materials

“…Supramolecular assembly, mostly based on host–guest interactions, is a promising approach for the development of solution processable luminescent materials . The environment (polarity, viscosity, concentration) as well as external stimuli (pH, heat, light, and ionic species) govern the tunable luminescence behavior of the host–guest assembly . In this context, cucurbit[8]uril (Q[8])‐based host–guest chemistry was demonstrated to achieve white light emission by Tao and co‐workers (Figure ) .…”

“…The quality and the quantum efficiency of the WLE materials are the predominant governing factors to transfer them from the laboratory to the marketplace. Considering the concept of additive mixing, enormous attention has been paid by different research groups on the fabrication of WLE materials employing organic, inorganic, and organic–inorganic hybrid scaffolds . We restrict our discussion to the recent development of all‐organic WLE materials .…”

A nano-cocktail of an NIR-II emissive fluorophore and organoplatinum(ii) metallacycle for efficient cancer imaging and therapy

“…[1][2][3] Considering their potential application in biomedicine, a series of metal-based SCCs especially organoplatinum(II)-based ones have been recently actively explored to serve as cell imaging and antitumor agents owing to their promising properties such as great efficacy in inhibiting tumor growth and low toxicity for normal tissues compared with clinical Pt(II) drugs. [4][5][6][7][8][9] Meanwhile, Pt(II)-based SCCs demonstrate interesting photo-physical properties including the ability to emit in the visible spectrum, allowing the delivery and release of organoplatinum(II) to be monitored at the cellular level. 5,[10][11][12][13] Despite these excellent properties, the potential decomposition of organoplatinum(II)-based SCCs in the presence of amino acids (histidine, lysine, arginine etc.)…”

“…[4][5][6][7][8][9] Meanwhile, Pt(II)-based SCCs demonstrate interesting photo-physical properties including the ability to emit in the visible spectrum, allowing the delivery and release of organoplatinum(II) to be monitored at the cellular level. 5,[10][11][12][13] Despite these excellent properties, the potential decomposition of organoplatinum(II)-based SCCs in the presence of amino acids (histidine, lysine, arginine etc.) is the major obstacle for successful in vivo applications.…”

Self-assembled sialyllactosyl probes with aggregation-enhanced properties for ratiometric detection and blocking of influenza viruses

“…Recently, a number of elegant supramolecular materials have been designed and constructed for biomedical uses [11][12][13]. These include fluorescent multilayer microcapsules and organic Janus microspheres formed by hydrogen bonding and electrostatic interactions [14][15][16][17], fluorescent J-aggregates formed by p-p stacking [18], chirality-driven self-sorting supramolecular materials [19], metallacycle-cored supramolecular assemblies [20], and other forms of nanoparticles [21,22] and nanospheres [23] based on host-guest supramolecular interactions. However, supramolecular materials suitable for IV detection and blocking remain exclusive.…”