Methyl Cinnamate-Derived Fluorescent Rigid Organogels Based on Cooperative π–π Stacking and CO···π Interactions Instead of H‑Bonding and Alkyl Chains

A new class of rigid low-molecular-mass organic gelators (LMOGs) was synthesized by McMurry and Heck reactions, and their gels and photophysical properties were investigated. The LMOGs lacked alkyl chain and H-bonding units and produced good gelation ability in selected mixed organic solvents facilitated by cooperative π–π stacking and CO···π interactions. Sensitive gel–sol transformation by molecular aggregation and disaggregation was easily achieved upon heating and cooling. H–H 2D NOESY and X-ray diffraction (XRD) patterns showed the π–π stacking and CO···π interactions between tiny methyl acrylate groups as “tails”. Importantly, this soft interaction model offers a useful tool for the future design and construction of supramolecular structures. At present, the LMOGs reported herein offer a sensitive gel-formation ability and aggregation-induced emission (AIE) property and thus have promising application potentials as functional soft matter in amorphous materials, photoelectric materials, and so on

Positively Charged Hyperbranched Polymers with Tunable Fluorescence and Cell Imaging Application

Fluorescence-tunable materials are becoming increasingly attractive because of their potential applications in optics, electronics, and biomedical technology. Herein, a multicolor molecular pixel system is realized using a simple copolymerization method. Bleeding of two complementary colors from blue and yellow fluorescence segments reproduced serious multicolor fluorescence materials. Interestingly, the emission colors of the polymers can be fine-tuned in the solid state, solution phase, and in hydrogel state. More importantly, the positive fluorescent polymers exhibited cell-membrane permeable ability and were found to accumulate on the cell nucleus, exhibiting remarkable selectivity to give bright fluorescence. The DNA/RNA selectivity experiments in vitro and in vivo verified that [tris­(4-(pyridin-4-yl)­phenyl)­amine]-[1,8-dibromooctane] has prominent selectivity to DNA over RNA inside cells

AIE-Active Tetraphenylethylene Cross-Linked <i>N</i>‑Isopropylacrylamide Polymer: A Long-Term Fluorescent Cellular Tracker

There is a great demand to understand cell transplantation, migration, division, fusion, and lysis. Correspondingly, illuminant object-labeled bioprobes have been employed as long-term cellular tracers, which could provide valuable insights into detecting these biological processes. In this work, we designed and synthesized a fluorescent polymer, which was comprised of hydrophilic <i>N</i>-isopropylacrylamide polymers as matrix and a hydrophobic tetraphenylethene (TPE) unit as AIE-active cross-linkers (DDBV). It was found that when the feed molar ratio of <i>N</i>-isopropylacrylamides to cross-linkers was 22:1, the produced polymers demonstrated the desirable LCST at 37.5 °C. And also, the temperature sensitivity of polymers could induce phase transfer within a narrow window (32–38 °C). Meanwhile, phase transfer was able to lead the florescent response. And thus, we concluded that two responses occur when one stimulus is input. Therefore, the new cross-linker of DDBV rendered a new performance from PNIPAm and a new chance to create new materials. Moreover, the resulted polymers demonstrated very good biocompatibility with living A549 human lung adenocarcinoma cells and L929 mouse fibroblast cells, respectively. Both of these cells retained very active viabilities in the concentration range of 7.8–125 μL/mg of polymers. Notably, P­[(NIPAm)₂₂–(DDBV)₁] (P6) could be readily internalized by living cells with a noninvasive manner. The cellular staining by the fluorescent polymer is so indelible that it enables cell tracing for at least 10 passages

Various Tetraphenylethene-Based AIEgens with Four Functional Polymer Arms: Versatile Synthetic Approach and Photophysical Properties

There are a lot of demands to develop abundant superior properties of aggregation-induced emission (AIE) polymers used in the aggregation state. Here we report a practical and versatile approach for the preparation of AIE polymers by conventional free radical polymerization. As an initiator, TPE-AZO has an excellent ability to initiate polymerization of various kinds of vinyl monomers to obtain AIE functional materials. It was found that TPE polymers emit multiple colors with wavelengths ranging from 370 to 482 nm, and they also exhibit the advantages of combining the AIE characteristic with unique properties of polymers. The fluorescence properties of temperature-sensitive TPE-PNIPAM, pH-sensitive TPE-PMAA, and counterion-sensitive TPE-PMETAC were investigated, and the results indicated that all of the responsive behaviors of the three TPE polymers were related to the change in fluorescence. Our versatile approach would provide a platform to fabricate AIE polymers with various superior properties using the azo-based AIE molecular initiator under mild conditions