The first example of a 3-alkene polymerization has been successfully achieved with 3-heptene in the presence of phenyl-substituted α- diimine nickel precatalysts activated by dMMAO, and compared with the corresponding linear alkenes, i.e., 1-pentene, 2-hexene and 4-octene polymerizations. The microstructures of the produced poly(3-heptene), which consists of ethyl , propyl and butyl branches indicated the 3,4- and 4,3-insertion, followed by chain-walking, with incorporation of a small fraction of long methylene sequences of 1,7-enchainment via monomer-isomerization. Late-transition metal catalyzed polymerization reactions of internal alkenes to synthesize novel polyolefin materials are highly important and also highly challenging. Upon activation with dried modified methylaluminoxane (dMMAO), the first example of a 3-alkene polymerization has been successfully achieved for 3-heptene catalyzed by phenyl-substituted α- diimine nickel complexes in comparison, and compared with the polymerizations of the corresponding linear alkenes, i.e., 1-pentene, 2-hexene and 4-octene. The results indicate that the polymerization of 3-heptene was achieved via chain-walking to generate branched amorphous polymers with glass transition temperature of ca. −68 °C. The microstructures of the produced poly(3-heptene) indicated the 3,4- and 4,3-insertion followed by chain-walking, the latter being predominant. The NMR analyses of the polymers showed that the obtained poly(3-heptene) possessed ethyl, propyl and butyl branches and a small amount of the long methylene sequence of 1,7-enchainment via monomer-isomerization. The branches structures were significantly dependent on the polymerization temperature, and the content of propyl branches derived from 3,4-insertion decreased with an increase in the polymerization temperature.
The antifungal activity of six microbial-derived volatile organic compounds (VOCs) [ 3-hepten-2-one (Hep), cis-3-octen-1-ol, 3-methylvalerate, isovalerate, 1-octen-3-ol (Oct), and 2-methylbutyrate] against Aspergillus flavus was investigated by determining the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI). The results demonstrated that all 15 binary combinations of the VOCs presented additive effects against A. flavus . Among them, the combination of Hep and Oct, refers to C OH , with concentrations of 2 μL L −1 and 2.5 μL L −1 , respectively, displayed the most potent antifungal effect with the lowest concentration, in contrast to the individual MIC of Hep or Oct, which were reduced to 1/8 and 1/2. C OH can induce membrane lipid peroxidation, enhance cell membrane permeability, and cause leakage of nucleic acids and proteins within the cell, and 1-octen-3-ol might play a leading role. Finally, applying C OH at a concentration of 1/2 MIC Oct + 1/4 MIC Hep could effectively restrain the spread of A. flavus on wolfberries and exhibit excellent preservation effects. This study validates the antifungal effect of C OH and may serve as a natural alternative to antimicrobial agents for post-harvest agricultural products.
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