Junda Huo,Dongxu Zhang,Debin Ni,Shan Wang,Qianyou Wang,Li Yang
The crystal morphology of energetic materials significantly affects their sensitivity, initiation capability, and flowability, which directly determine the performance of weapons and equipment. Despite great efforts having been devoted to the morphological control of primary explosives, the mechanism insights into morphological modification are still in infancy stage. Herein, combining experimental results with theoretical calculations, we elucidated the morphological control process of a novel environmentally friendly lead-free primary explosive named bis-(ethylenediamine) copper (II) 5-nitrotetrazolate [Cu(EDA) 2 (NT) 2 ]. Through directional suppression/induction by different surfactants on crystal face growth, three completely different shaped crystals of Cu(EDA) 2 (NT) 2 (lamellar, hollow rhombic toroidal, and uniform rhombic block) were prepared, ultimately achieving precise control over the crystal morphology. Among them, the block-shaped crystals of CMC-Cu(EDA) 2 (NT) 2 , modified with carboxymethyl cellulose, exhibited significantly improved stacking density, thermal stability, and initiation capability. This work not only significantly optimized the modification of Cu(EDA) 2 (NT) 2 , but also revealed the complex interaction mechanism between surfactants and crystal surfaces, laying an important scientific foundation for tailoring morphology, and enhancing performance of primary explosives crystals.
He Wang,Yanjing Guo,Qing Liu,Jing Zhang,Qianlong Zhang,Mingying Yang,Qizhen Chen,Sheng Qiang,Bernal E. Valverde,Shiguo Chen
The tetramic acid moiety is a pivotal structural unit in numerous natural products. As an analogue of the simplest tetramic acid compound tenuazonic acid (TeA), sec-pentyl-TeA (S-TeA) exhibits double herbicidal activity of TeA. Here, this work identifies S-TeA as a novel natural product synthesized by Alternaria alternata and three other filamentous fungi. Chiral analysis confirm the absolute configuration of natural S-TeA as (5 S , 6 S ). Configuration-bioactivity studies reveal that natural (5 S , 6 S )-S-TeA is the eutomer and possesses the highest herbicidal activity among all tested diastereomers. Biosynthetic analyses demonstrate that threonine is the precursor to S-TeA, beginning with the production of 2-amino-3-methylhexanoic acid (AMHA) via eight enzymes from the branched-chain amino acid (BCAA) biosynthetic pathway, including threonine deaminase, 2-isopropylmalate synthase (IPMS), 3-isopropylmalate dehydratase (IPMDH), isopropylmalate dehydrogenase (ISMD), acetolactate synthase, ketol-acid reductoisomerase, dihydroxy acid dehydratase, and BCAA aminotransferase. Subsequently, AMHA undergoes acetylation and cyclization by non-ribosomal peptide synthetases to form S-TeA. Distinct differences in the biosynthetic pathways of S-TeA and TeA are identified. In vitro studies confirm the critical roles of three unique enzymes IPMS, IPMDH, and ISMD in S-TeA biosynthesis, which are absent in TeA biosynthesis. These findings provide a solid basis for developing S-TeA as a natural product herbicide.
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