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Nitro compounds are widely used in modern industries. Among them, 2, 4-dinitrophenylhydrazine (DNH) is extremely harmful. It is of great significance to develop methods for the detection of DNH. In this work, chitosan was used as the substrate material, and fluoroborondipyrrole (BODIPY) was used as the fluorophore. Chitosan was endowed with the fluorescence sensing ability by the introduction of BODIPY units. First, BODIPY derivatives (NO-3 and BO-1) with an alkynyl group (C≡C) were synthesized. Second, small molecules NO-4 and BO-2 with an aldehyde group (–CHO) were obtained. Finally, the –NH2 groups on chitosan underwent a click reaction (–NH2/C≡C) and a Schiff base formation reaction occurred (–NH2/–CHO) to form three polymer probes C1, C2 and C3. C＝C formed in the click reaction can interact with DNH and can be used as recognizing sites for DNH. These chitosan probes have good thermal stability and could selectively recognize DNH, showing notable fluorescence quenching effects, which are visible to the naked eye. DNH is a typical electron-deficient compound, and the polymer fluorescent probe contains electron-rich groups, which makes it easier for the two species to combine and cause fluorescence changes. C1 is flexibly cross-linked, C3 is rigidly cross-linked, and C2 has a non-crosslinked structure, and they show different rheological properties. This work expands the application of chitosan. [ABSTRACT FROM AUTHOR]

Multi-component polymers (MCPs) incorporate multiple components into the main chain or pendant group and have special functions. In this work, the small-molecule fluorescent boron-dipyrromethene (BODIPY), with ester groups and/or alkoxyl long chains, was synthesized first. Then, this small-molecule BODIPY and the components containing C＝C bonds (HD and PD) were reacted via the Heck coupling reaction to obtain macromolecular probes that perform different functions. With the help of ester groups and alkoxyl "tail", polymers MCP1 and MCP2 were soluble in a variety of water-miscible organic solvents. Moreover, MCP3 and MCP4 were completely soluble in water. These macromolecular probes showed sensitive and selective recognition toward Hg2+/Hg+ because of the introduced components (HD and PD) containing C＝C bonds. After binding to Hg2+/Hg+, MCP1 and MCP2 demonstrated fluorescence quenching and color changes, which allowed the dual-channel specific detection of Hg2+/Hg+. Compared with the probes containing HD, the probes containing PD showed higher sensitivity, and the good recognition ability caused the detection limit to be as low as 0.32 μM, which may be due to the "molecular wire" mechanism. The small-molecule components with different functional groups were polymerized into fluorescent polymer materials. This methodology endows the polymer probe with good solubility and high sensitivity, and the as-prepared polymers could sense metal ions in aqueous environments. [ABSTRACT FROM AUTHOR]

Fifteen azomethine compounds based on different rigid cores and soft aliphatic tails have been designed and synthesized to generate variable supramolecular architectures with distinct thermotropic, photophysical and electrochemical properties. Ten out of the fifteen imines were grown as single crystals and their molecular structures and supramolecular architectures were determined by single-crystal X-ray diffraction. Thermotropic behavior was monitored by polarized-light microscopy and differential scanning calorimetry. Photophysical properties were studied by UV-vis and photoluminescence spectroscopy and electrochemical properties by cyclic voltammetry. It was demonstrated that all supramolecular architectures were mostly generated via weak π–π or van der Waals interactions between the rigid cores, which prompts the synthesis of molecular glasses, further giving rise to large crystals displaying an aggregation-induced emission (AIE) effect. We conclude that there is a close relationship between the molecular structures of the imines and their ability to promote favorable properties for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Betulin is a naturally originating terpenoid, which attracted the attention of researchers due to its bioactive properties, including antitumor activity. This paper reports new betulin-imine derivatives, their synthesis, structural characterization and investigation of their antioxidant and anticancer activities. To this aim, a betulin aldehyde has been firstly prepared via an oxidation reaction using a Tempo reagent, which was further reacted with a series of aliphatic amines via an acid condensation reaction. The proposed chemical structures were confirmed using 1H-NMR and FTIR spectroscopy and single crystal X-ray diffraction, and characterized by solubility tests, ultraviolet-visible (UV-Vis) and photoluminescence spectroscopy, thermogravimetric analysis and polarized light microscopy. All the compounds were easily soluble in common organic solvents, and showed good thermal stability. They showed strong birefringence under polarized light indicating their crystalline nature, which was attributed to single crystal diffraction and they belong to the Sohnke P212121 space groups. The investigation of optical properties using photoluminescence spectroscopy revealed that all the imines emitted blue light in solution and in the solid state. The DPPH radical scavenging test showed that the antioxidant activity of betulin was significantly improved by imination with the increase of the aliphatic chain length. The antitumor activity investigated in vitro using the MTS assay on human breast cancer cell line MCF-7 (adenocarcinoma) and on non-tumorigenic epithelial cell line MCF-10A showed that the betulin-imine derivatives have improved antitumor activity and selectivity compared to neat betulin, suggesting that a medium length of the alkyl chain is favorable for the antiproliferative activity. [ABSTRACT FROM AUTHOR]

Detection of heavy metals with high sensitivity and selectivity is of vital importance. In this study, we report the synthesis of small molecular chemosensors and the fabrication of corresponding macromolecular fluorescent chemosensors. Boron dipyrrole methane (BODIPY)-derived chemosensors, BE and BB, were designed and synthesized first. Then, they were incorporated into polymeric derivatives to prepare macromolecular fluorescent chemosensors. The small molecular sensors were highly sensitive and selective to Hg2+. Other ions and albumin did not exhibit clear interference to the sensing of Hg2+ ions. Once the macromolecular chemosensors were formed, the recognition ability was preserved; moreover, the sensitivity was even enhanced by the “molecular wire” mechanism. The minimum detection limits of four macromolecular chemosensors, PBEP, PBEB, PBBP and PBBB, for Hg2+ reached 2.05 μM, 0.23 μM, 4.23 μM, and 0.15 μM, respectively. Under natural light, the addition of Hg2+ led to significant color changes; also, they can be used as Hg2+-sensitive “naked eye” indicators in the natural environment. [ABSTRACT FROM AUTHOR]