Valadbeigi Younes, Ilbeigi Vahideh, Michalczuk Bartosz, Sabo Martin, Matejcik Stefan
Department of Chemistry, Faculty of Science , Imam Khomeini International University , Qazvin , Iran.
TOF Tech. Pars Company , Isfahan Science & Technology Town , Isfahan , Iran.
J Phys Chem A. 2019 Jan 10;123(1):313-322. doi: 10.1021/acs.jpca.8b11417. Epub 2018 Dec 20.
Ionization of 2-nonanone, cyclopentanone, acetophenone, pyridine, and di- tert-butylpyridine (DTBP) in a corona discharge (CD) atmospheric pressure chemical ionization (APCI) ion source was studied using ion mobility (IMS) and time-of-flight mass spectrometry (TOF-MS). The IMS and MS spectra were recorded in the absence and presence of ammonia dopant. Without NH dopant, the reactant ion (RI) was H(HO) , n = 3,4, and the MH(HO) clusters were produced as product ions. Modeling of hydration shows that the amount of hydration ( x) depends on basicity of M, temperature and water concentration of drift tube. In the presence of ammonia (NH(HO) as RI) two kinds of product ions, MH(HO) and MNH(HO) , were produced, depending on the basicity of M. With NH(HO) as RI, the product ions of pyridine and DTBP with higher basicity were MH(HO) while cyclopentanone, 2-nonanone, and acetophenone with lower basicity produce MNH(HO) . To interpret the formation of product ions, the interaction energies of M-H, H-NH, and H-OH in the M-H-NH and M-H-OH and M-H-M complexes were computed by B3LYP/6-311++G(d,p) method. It was found that for a molecule M with high basicity, the M-H interaction is strong leading in weakening of the H-NH, and H-OH interactions in the M-H-NH and M-H-OH complexes.
利用离子迁移率（IMS）和飞行时间质谱（TOF-MS）研究了在电晕放电（CD）大气压化学电离（APCI）离子源中2-壬酮、环戊酮、苯乙酮、吡啶和二叔丁基吡啶（DTBP）的电离情况。在不存在和存在氨掺杂剂的情况下记录了IMS和MS光谱。在没有NH掺杂剂时，反应物离子（RI）为H(HO) ，n = 3,4，并且生成MH(HO) 簇作为产物离子。水合作用建模表明水合量（x）取决于M的碱度、温度和漂移管中的水浓度。在存在氨（NH(HO) 作为RI）的情况下，根据M的碱度产生了两种产物离子，即MH(HO) 和MNH(HO) 。以NH(HO) 作为RI时，碱度较高的吡啶和DTBP的产物离子为MH(HO) ，而碱度较低的环戊酮、2-壬酮和苯乙酮则产生MNH(HO) 。为了解释产物离子的形成，通过B3LYP/6-311++G(d,p)方法计算了M-H-NH、M-H-OH和M-H-M络合物中M-H、H-NH和H-OH的相互作用能。结果发现，对于碱度高的分子M，M-H相互作用很强，导致M-H-NH和M-H-OH络合物中H-NH和H-OH相互作用减弱。
