Enhancing the Circularly Polarized Luminescence of Self-assembled Cyanostilbenes through Extended π-Conjugation

Chiral supramolecular assembly of π-conjugated luminophores provides a promising avenue for enhancing circularly polarized luminescence.In this study,we shed light on the impact of π-conjugation length on circularly polarized luminescent performance of the resulting supramolecular assemblies,by designing a tetra-cyanostilbene monomeric compound alongside two dicyanostilbene control compounds.These cyanostilbene-based compounds possess the ability to form chiral supramolecular polymers in toluene,driven by a synergistic combination of intermolecular hydrogen bonding and π-stacking interactions.The extended π π-aromatic skeleton brings bathochromic-shifted fluorescence and enhanced intermolecular stacking capability for the tetra-cyanostilbene compound.Consequently,chiral supramolecular assemblies formed by the tetra-cyanostilbene compound demonstrate a remarkable two-fold increase in g_(lum) values relative to the assemblies formed by the dicyanostilbene compounds.Overall,this study provides valuable insights into the relationship between-conjugation length and the circularly polarized luminescent performance of π-conjugatedsupramolecularassemblies.

Merging non-covalent and covalent crosslinking:En route to single chain nanoparticles

Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm.Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters complex energy landscapes,leading to the potential occurrence of misfolding issues.While noncovalent crosslinking can circumvent this issue,the resulting single-chain nanoparticles exhibit lower structural stability compared to their covalently crosslinked counterparts.In this study,we present a novel approach for the synthesis of single-chain nanoparticles,achieved through the combination of non-covalent and covalent intramolecular crosslinking.Cyanostilbenes grafted onto the linear polymer form intrachain non-covalent stacks aided by hydrogen bonds,leading to the formation of non-covalently crosslinked single-chain nanoparticles.These nanoparticles undergo conversion to covalently crosslinked nanostructures through subsequent photo-irradiation using[2+2]photocycloaddition,a process facilitated by the supramolecular confinement effect.Consequently,the resulting single-chain nanoparticles demonstrate both intrachain folding efficiency and substantial stability,offering significant potential for advancing applications across diverse fields.

White light emission from AIE-active luminescent organic materials

Fluorescent organic materials that exhibit unique aggregation-induced emission have been utilized for various applications,including white light emission(WLE).The materials typically rely on composite designs involving a mixture of compounds emitting at different wavelengths of light.To overcome the limitations offered by the design of such composite mixtures,tremendous efforts were also emphasized in developing single-molecule substrates that emit white light.The white light by either method is typically controlled by the solvent polarity,energy and charge transfer,host-guest interactions,gelation,or embedding in the polymer or organic frameworks.This article briefly reviews various molecules exhibiting aggregation-induced emission behavior and emitting white light.

π-Conjugated cyanostilbene-based optoelectric functional materials

π-Conjugated organic luminescent materials are essential components for modern optical and photoelectric research.This review mainly probes into the recent work in the progress of smart π-conjugated organic systems in the form of cyanostilbene and its derivatives,which can regulate its excellent features in response to a variety of physical or chemical stimuli（e.g.viscosity,light,magnetism,electric field,polarity,pH and solvent environment）.As a result of its extensive applicability and adaptability,cyanostilbene and its derivatives have been planted into different structural architectures such as polymers,functional nanoparticles,solid membranes,supramolecular systems and so on.This review will first give a general description of the preparation and characterization of cyanostilbenebased optoelectric luminophores and then focus on their peculiar functional properties in the need for advanced material applications,such as AIEE（aggregation-induced enhanced emission effect）,solidstate emission,photovoltaics,photolithography and photochromism to be further processed afterwards.The purpose of this review is to give a platform of practical organic materials,mostly cyanostilbene and its derivatives,based on stable aromatic derivatives,to contribute to the booming of modern π-conjugated photoelectric materials that integrate with contemporary physics,material chemistry,bioengineering,medical science and aerospace altogether.

Newπ-conjugated cyanostilbene derivatives:Synthesis,characterization and aggregation-induced emission

Two novel Jr-conjugated cyanostilbene derivatives, FLU-CNPH and TPE-CNPH, were designed aria synthesized by introducing the strong electron donor 1, 4-dihydropyrro[3,2-b]indole and AIE electron donor tetraphenylethylene （TPE） to the （3＇,5＇-bis（trifluoromethyl）-biphenyl-4-yl）-acetonitrile, respec- tively, Both of them were fully characterized and their AIE behaviors were investigated using fluorescence spectroscopy and FE-SEM images. Their optimized structures and frontier molecular orbitals were calculated with the DFT by using Materials Studio 7,0 software to study the relationship between the structure and properties.

A cyanostilbene-based molecule with aggregation-induced emission properties: amplified spontaneous emission, protonation effect and electroluminescence

A terpyridine-substituted cyanostilbene derivative(Z)-2-(4′-([2,2′:6′,2″-terpyridin]-4′-yl)-[1,1′-biphenyl]-4-yl)-3-phenylacrylonitrile(CNSTPy) was synthesized and characterized. The compound exhibits remarkable aggregation-induced emission phenomenon and its single crystal shows a blue emission with fluorescent efficiency as high as 45%. Based on its aggregation state behavior, multiple applications towards exploring its lasing, fluorescence switching and electroluminescence properties were realized. Amplified spontaneous emission(ASE) was observed from the crystal and verified by the variable pump strip method, with a threshold value of ～1.5 m J cm^(-2). The protonation/deprotonation processes accompanied by the formation of different molecular aggregation structure result in the distinct blue and yellow emissions. Additionally, the molecule also shows a moderate electroluminescence performance.