Nonconventional Luminescence Enhanced by Silicone‐Induced Aggregation

Abstract

Nonconventional organic luminogens have attracted ag reat deal of interestso wing to their intriguing properties (e.g.,unusualfluorescence emission) and promising applications. According to previous studies, it was found that introduction of Si-O could enhancet he fluorescence emission of the luminogens. Herein, we have synthesized somefluorescent siloxanederivatives and similar moleculesw ithout Si-O units by simple and efficient modificationt oi nvestigate the role of Si-O units in the emission. It was found that the strong emission could be observed in dilute solutions of siloxane derivatives, but not in the carbon compounds. UV/Vis absorption, fluorescence spectra, nuclear magnetic resonance spectra,a nd theoreticalc alculations indicated that the heteroatom and the Si-Ou nit formed the coordination bond in the siloxane derivatives, resulting in enhanced fluorescencee mission.Recently,o rganic luminogens have rapidlyd eveloped in the fields of organic light-emitting diodes (OLEDs), biological materials, sensors, and drug delivery.[1] However,c onventionalo rganic luminogens have an obvious disadvantage,c oncentration quenching, also called aggregation-caused quenching (ACQ) effect, limiting their applications. To overcome this drawback, one effective strategyi sd eveloping, aggregation-induced emission (AIE) or aggregation-enhanced emission (AEE), which was proposed by Ta ng and co-workersin2 001.[2] Instead of an ACQ effect, AIE luminogens can emit unexpected bright fluorescencei nc oncentrated solutionso re ven in solid states. [3] For example, tetraphenylethene (TPE)-based derivatives, as at ypicalc lass of AIE luminogens,a re non-emissive in molecularly dissolved state buth ighlye missive in aggregated state, because the ACQ effect can be inhibited by the propellershaped structure.[4] Moreover,t heir optical properties can be fine-tuned by modifying the aryl rings with various multiple functional groups.[5] Another effective strategy is developing nonconventional luminogens only containing nonconventional chromophores such as an aliphatic tertiary amine, [6] amide, [7] nitrile,[10] C = C, [11] epoxy, [12] or heteroatoms.[13]Generally,n onconventional luminogens are not composed of traditional aromatic units or constructed by bulky conjugation. Compared to AIE luminogens, these compounds possess specific advantages including facile synthesis, low toxicitya nd biocompatibility,w hich can lead to applicationsi nm aterial science, biology, chemistry and optic materials. Therefore, designing nonconventional luminescentm aterials with improved performance becomes an impending task and has attracted ag reat deal of interest. [8,10, 14] Since the unexpected luminescence from archetypal poly(amidoamine)s (PAMAM) was reported, more and more nonconventional fluorescent polymers have been designed and synthesized. The nonconventional organic luminogens always exist as dendrimers, [15] hyperbranched polymers, [16] or even linear polymers, [17] such as polyurea dendrimers, [9] poly(aminoester)s (PAE), [8]...

Multiring-induced multicolour emission: hyperbranched polysiloxane with silicon bridge for data encryption

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Clustering-Triggered Emission of Carboxymethylated Nanocellulose

“…Most clustering-triggered emission (CTE) luminogens have been fabricated by precipitation of precursor organic molecules and polymers (Mohamed et al, 2015; Li et al, 2017; Lu et al, 2017). However, few works have explored the luminescence of natural products with low cost and good biocompatibility (Zhao et al, 2016).…”

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