Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Dipartimento di Chimica, Università degli studi di Roma La Sapienza, P.le Aldo Moro 5, 00185, Roma, Italy.
Istituto di Struttura della Materia (ISM-CNR), Area della Ricerca di Roma 1, Via Salaria Km 29,300, 00016, Monterotondo Scalo (RM), Italy.
Chemphyschem. 2021 Dec 3;22(23):2387-2391. doi: 10.1002/cphc.202100629. Epub 2021 Oct 12.
Nitroimidazoles are a class of chemicals with a remarkable broad spectrum of applications from the production of explosives to the use as radiosensitizers in radiotherapy. The understanding of thedynamics of their fragmentation induced by ionizing sources is of fundamental interest. The goal of this work is to theoretically investigate the kinetic competition between the two most important decomposition channels of 2, 4 and 5-Nitroimidazole cations: the NO and NO losses. The calculated rate constants of the two processes are in very good agreement with the experimental Photoelectron-Photoion Coincidence (PEPICO) branching ratio. This study solves the intriguing and theoretically unexplained experimental observation that 2-Nitroimidazole, at variance with the other two regio-isomers is a source for only NO at low energies (<12.76 eV). This is a key point for biomedical application of the nitroimidazoles, because NO is the vasodilator that favors the reoxigenation of hypoxic tumor tissues.
硝咪唑类化合物是一类具有广泛应用的化学物质，从爆炸物的生产到放射治疗中的增敏剂。了解其在电离源作用下的碎裂动力学具有重要的理论意义。本工作的目的是从理论上研究 2-、4-和 5-硝咪唑阳离子两种最重要的分解通道：NO 和 NO 损失之间的动力学竞争。两种过程的计算速率常数与实验光电离-光电离符合（PEPICO）分支比非常吻合。该研究解决了一个有趣的、理论上尚未解释的实验观察结果，即 2-硝咪唑与其他两个区域异构体不同，在低能量（<12.76 eV）下仅为 NO 的来源。这对于硝咪唑类化合物在生物医学中的应用是一个关键点，因为 NO 是血管扩张剂，有利于缺氧肿瘤组织的再氧化。
