Non‐Conjugated Polymer Dots with Crosslink‐Enhanced Emission in the Absence of Fluorophore Units

Abstract

A new type of fluorescent material is presented, which is called non-conjugated polymer dots (NCPDs). The NCPDs only possess sub-fluorophores (which are groups such as C=O, C=N, N=O) instead of typical conjugated fluorophore groups, and thus these materials should not have strong photoluminescence (PL) in the usual sense. Nevertheless, the PL of these sub-fluorophores can be enhanced by chemical crosslinking or physical immobilization of polymer chains, which is named the crosslink-enhanced emission (CEE) effect. The significant advances achieved by us and other groups on both experimental and theoretical aspects are discussed, and the covalent-bond CEE, rigidity-aggregated CEE, or supramolecular CEE in NCPDs is elaborated. Moreover, synthetic strategies, unique optical properties, and the promise of NCPDs in bio-related fields, such as bioimaging and drug delivery, are systematically discussed.

Facile, Quick, and Gram‐Scale Synthesis of Ultralong‐Lifetime Room‐Temperature‐Phosphorescent Carbon Dots by Microwave Irradiation

“…Accordingly,the DE ST value was calculated to be 0.62 eV (FL and phosphorescence emission wavelengths being taken under the excitation of 350 nm based on their excitation spectra, Figures S7-S9), and this small value is favorable for an effective ISC process to populate triplet excitons. [26,28,47,48] Thehigh-content of the doping elements Na nd Ph as also been confirmed, which would facilitate the ISC for effectively populating triplet excitons. First, the selected raw materials are important, because 1) ethanolamine could potentially serve both as carbon source for carbonization and aNsource for doping.…”

“…Moreover,l ow temperature (77 K) FL and phosphorescence spectra of the CDs were carried out to quantitatively evaluate energy gap between the lowest T 1 and S 1 (DE ST ). In addition amino groups have been demonstrated to be an effective sub-fluorophore that is responsible for FL emission of non-conjugated polymer CDs; [47,48] 2) phosphoric acid could also play multiple functions,s erving as an acid catalyst for boosting dehydration carbonization of ethanolamine,acrosslink agent for polymerization, and providing aP source for doping;3 )both of the two raw materials could provide possible sites for forming hydrogen bonds.T hen, crosslink polymerization, oxidation, and dehydration carbonization reactions could occur during the formation of the URTP CDs by the microwave-assisted heating treatment of the ethanolamine and phosphoric acid solution. [26] According to the above discussion, formation of the CDs and their URTP origins could be tentatively proposed as followed.…”

Piezochromic Carbon Dots with Two‐photon Fluorescence

“…[9] Optical properties of CDs are determined by the combination and competition of the effects of these factors. [11] In our previous work, we reported different systems for preparing intense blue,g reen, deep red, and white emissive CDs,w hich were obtained by ah ydrothermal route from small molecules. [11] In our previous work, we reported different systems for preparing intense blue,g reen, deep red, and white emissive CDs,w hich were obtained by ah ydrothermal route from small molecules.…”

Cross‐Linkable Liquid‐Crystalline Biopolyesteramide as a Multifunctional Polymeric Platform Designed from Corn Oil Side‐Stream Product of Bioethanol Industry

“…In certain cases, sub‐fluorophore groups, which usually presents very weak PL properties, such as heteroatomic double bonds or amino groups can be “immobilized” to design non‐conjugated polymer dots with high fluorescence properties. Motion restriction of these sub‐fluorophores by means of physical interaction or chemical cross‐linking allows great enhancement of the radiative transition and thus results in PL with a typical blue emission . For PCnO, it was previously hypothesized that a micelle or vesicle organization was present in the THF because of the low value of α obtained from the M‐H plot.…”