Functionalization of microcrystalline cellulose (MCC) with EDTA dianhydride (EDTAD) was first achieved using an esterification reaction. N-Hydroxysuccinimide-activated MCC-EDTAD ester (MEN), a novel macromolecule crosslinker based on MCC, was synthesized for the modification of gelatin films. The reaction between gelatin and MEN was verified by the residual free amino test, FTIR and XRD spectra. The introduction of MEN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance and water uptake ability. Additionally, SEM images proved the successful surface grafting reaction and degradation phenomenon. This unique gelatin film material with advanced properties broke the limitation of the blending method for modification of gelatin with macromolecules and broadened its application as a novel sustained-release material.
A three-dimensional hyperbranched polymer (3D-HP) with σ–π conjugated PDMPS (poly(dichloromethylphenylsilane)s) units covalently bonded to a polyhedral oligosilsesquioxane (POSS) scaffold was prepared by a one-step “thiol–ene click chemistry” reaction. Compared with POSS-based organic polymers, the 3D-HP with a flexible Si–Si chain showed enhanced solubility. This 3D hyperbranched polymer exhibited outstanding thermal stability and optimal photophysical properties. For probing nitroaromatics (NACs), the 3D-HP showed excellent sensitivity (Ksv = 2.83 × 104 M−1) against the presence of a tetrahydrofuran (THF) solution of 2,4,6-trinitrotoluene (TNT). In addition, the 3D-HP coated on glass films exposed to saturated DNT vapor exhibited a high quenching efficiency (ηEP) of the fluorescence of 3D-HP film, which was drastically suppressed (82%) for 300 s. The excellent fluorescent quenching performance of the 3D-HP can be attributed to the following points: (i) hyperbranched conjugated polymers afford multi-dimensional transport pathways for excitons migration; (ii) there exists in the polymer high electron affinity and rapid electron delocalization of σ–π conjugated polysilanes; (iii) noncovalent interactions between the electropositive δ+ Si atoms of σ–π conjugated polysilanes and N and/or O atoms of electron-deficient nitroaromatics (NACs) facilitate the adsorption of NACs. Furthermore, the bulky octathiol-POSS units in the 3D-HP can improve the permeability of the film sensor. This 3D hyperbranched σ–π conjugated polymer 3D-HP has the potential to be used to prepare sensitive, selective, and stable sensors for the detection of NACs explosives.
Four barbituric derivatives (1–4), were synthesized with obvious aggregation induced emission (AIE) or aggregation induced emission enhancement (AIEE) behaviors. The optical properties in different states and the mechanisms of the enhanced emission of 1–4 were investigated. We found that there were a large number of globular or blocky nanoparticles with average diameters from 229 to 394 nm in tetrahydrofuran (THF)/water solutions when the water fraction (fw) was 90%. The single crystal data of 2 and 4 reveal that multiple intermolecular interactions restrict the intramolecular motions, and promote the formation of a herringbone arrangement (4), thus permitting intense emission in the aggregate state. In addition, the frontier molecular orbital energy and band gap calculated by density functional theory (DFT) are consistent with the experimental results. Compound 4 is cell-permeable: upon entering the live cells, the dye molecules can accumulate in the lysosomes and turn on the fluorescence.
A new dibenzothiophene-based barbituric acid derivative ( DTB ) with an aggregation induced emission (AIE) effect was synthesized as a naked-eye colorimetric and fluorescent probe for CN − .
1 November 2019 in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy