In this study, we present a simple synthetic route for the preparation of narrowly distributed silver nanoparticles by using a phenolic hydroxyl modified chitosan as both reducing and capping agent. The effects of factors such as temperature and the concentration of both chitosan derivative and AgNO₃ were systematically investigated and optimized. It was shown that narrowly distributed silver nanoparticles with an average diameter of 4–5 nm were successfully prepared under the optimal conditions in just few minutes. The structure, morphology and physicochemical properties of the prepared silver nanoparticles were characterized in detail by a series of techniques. The roles of phenolic hydroxyl groups linked by Schiff base in the reduction and stabilization of silver nanoparticles were studied by comparison with a series of chitosan derivatives and the possible mechanism was proposed. These chitosan derivative stabilized silver nanoparticles, combining the unique properties of silver and chitosan, exhibited broad spectrum and excellent antimicrobial performance against different categories of both bacteria and plant fungi.

An efficient synthesis of 2-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylates was carried out under solvent-free conditions in an oven or microwave oven via the Knoevenagel condensation of salicylaldehydes with ethyl trifluoroacetoacetate followed by intramolecular cyclization in the presence of silica-immobilized L-proline. The structures of the title compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, HRMS and X-ray single crystal diffraction. The improved method described herein is economical, easily-operated and environmentally friendly. Furthermore, the catalyst can be recovered conveniently and reused without obvious loss of activity.

A versatile and environmentally friendly method for the synthesis of various organophosphorus compounds have been developed under microware conditions. We have synthesized a series of the trifluoromethyl phosphonates via Phospha-Brook rearrangement between dialkylphosphite and 3-(trifluoroacetyl)coumarins using KF/Al₂O₃ as a highly efficient solid catalyst under solventless conditions. Catalyst reuse, ease of separation of the pure product, and high yields are some of the unique features of this process. In addition, the mycelial growth rate method was used to examine the in vitro antifungal activities of the phosphates 4a-o against Phytophthora capsici, Fusarium oxysporum vasinfectum, Bipolaris maydis and Alternaria solani at 500 µg/mL. The results showed that compound 4n exhibited significant anti-Phytophthora capsici activity with inhibitory index of 86%.