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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]

In this work, fluorescent β- cyclodextrin (β-CD) based probes containing naphthalimide group were synthesized to realize the specific recognition of Hg2+/Hg+ in aqueous system. Firstly, three small fluorescent molecules (N1, N2 and N3) with -NH 2 groups were synthesized from 4-bromo-1, 8-naphthalene anhydride. Secondly, CH CCH 2 - group was introduced into β-CD by Williamson ether formation reaction. Finally, the target probes (β-CD-PI, β-CD-PY and β-CD-TP) were obtained by Amino-Yne click reaction. These probes can efficiently recognize Hg2+/Hg+. β-CD-PI emits bright yellow fluorescence after binding with Hg2+/Hg+, which is a turn-on fluorescent probe. When the Hg2+/Hg+ concentration exceeds 26 μM, the fluorescence intensity amplifies sharply (20 folds). The hydrophobic parts of the probes aggregated together to form a micelle-like structure due to complexation with Hg2+/Hg+, resulting in special micelle-sensitizing properties. Meanwhile, the HOMO-LUMO energy levels of the probes were calculated by cyclic voltammetry (CV). The probe is expected to be used for the detection of Hg2+/Hg+ in aqueous solutions without any organic solvents. [Display omitted] • Turn on fluorescent probes were prepared by a simple method. • Micellar sensitization effect leads to the amplifying fluorescence. • Specific identification of Hg2+/Hg+ ions. • Water solubility of the sensors was endowed by link of β-CD to the molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescence cellulose-based probes are synthesized. • The probes were sensitive and selective to explosives TNP and DNH. • Testing paper for TNP/DNH were obtained. 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenylhydrazine (DNH) are harmful to the environment and human beings. Trace detection of TNP and DNH is worth of developing facile methods. In this work, cellulose powder and filter paper based fluorescence sensor are synthesized. Firstly, NH 2 CH 2 CH 2 – was introduced into cellulose through etherification reaction, and at the same time, a small molecule BODIPY with –CHO was synthesized. Then BODIPY was incorporated into cellulose by Schiff base reaction to obtain fluorescent macromolecular probes. These fluorescent cellulose sensors can efficiently identify TNP and DNH, with the lowest detection limits of 2.8 × 10−7 M and 1.6 × 10−7 M, respectively. Fluorescent filter paper is obtained via the same route. They also exhibit TNP and DNH identification ability. The method developed in filter paper not only expands the application range of cellulose, but also can efficiently identify the pollutants TNP and DNH, which is of great significance in theory and practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent water-soluble polymer sensors were obtained by RAFT method. • Selective and sensitive recognition of Fe3+ and Fe2+. • Fluorophores could be incorporated as RAFT reagent and/or functional monomer. Fe3+ and Fe2+ are common metal ions in natural water environments and creatures. The development of water-soluble fluorescent sensors for detecting Fe2+/Fe3+ ions was of great significance. In this work, two kinds of boron fluoride dipyrrole (BODIPY) fluorescent small-molecules were synthesized firstly. One of the small molecules contains a thioester bond that can be used as a chain transfer agent to participate in the polymerization process, and the other contains an unsaturated C = C double bond at the meso position. Through the reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization method, methacrylic acid (MAA) and methacrylamide (MAM) were used as the main monomers, and small molecular fluorescent monomers were introduced to the end of the main chain. In this way, fluorescent macromolecules were obtained. The polymers were water soluble owing to the presence of long enough hydrophilic carboxyl and amide chains. These fluorescent probes exhibit high sensitivity to Fe2+/Fe3+, good selectivity, and anti-interference of other ions. The detection limit for Fe2+ was as low as 2.3 × 10−7 M, and the detection limit for Fe3+ can reach up to 4.5 × 10−7 M. The results show that these probes can be used as good sensors to identify Fe2+ and Fe3+. Moreover, the fluorophores could be incorporated into polymer chains as the RAFT reagents and/or functional monomers. [ABSTRACT FROM AUTHOR]