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当前位置: 首页 > 技术文献 > 应用文献 > 碱性和结构对质子化分子水化,质子结合的二聚体和团簇形成的影响:离子迁移-飞行时间质谱和理论研究
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碱性和结构对质子化分子水化,质子结合的二聚体和团簇形成的影响:离子迁移-飞行时间质谱和理论研究

来源: Younes Valadbeigi et al  发布日期: 2019-10-08  访问量: 82


通过配备电晕放电离子源的IMS-TOFMS技术研究了氨,甲醛,甲酸,丙酮,丁酮,2-辛酮,2-壬酮,苯乙酮,乙醇,吡啶及其衍生物的质子化,水合和团簇形成。已发现质子化分子MH +参与水化或团簇形成的趋势取决于M的碱度。具有较高碱度的分子的水合程度低于具有较低碱度的分子的水合程度。低碱性分子(例如甲醛)的质谱表现出较大的M n H +(H 2 O)n簇,而对于高碱性的化合物(例如吡啶),只有MH + 和MH +观察到M个峰...
标签: 质子二聚体、团簇、离子迁移谱、飞行时间质谱
 

EFFECT OF BASICITY AND STRUCTURE ON THE HYDRATION OF PROTONATED MOLECULES, PROTON-BOUND DIMER AND CLUSTER FORMATION: AN ION MOBILITY-TIME OF FLIGHT MASS SPECTROMETRY AND THEORETICAL STUDY

碱性和结构对质子化分子水化,质子结合的二聚体和团簇形成的影响:离子迁移-飞行时间质谱和理论研究

Younes Valadbeigi,1 Vahideh Ilbeigi,2
Bartosz Michalczuk,3 Martin Sabo,3 Stefan Matejcik3
1Department of Chemistry, Faculty of Science, Imam Khomeini International University, Qazvin, Iran
2TOF Tech. Pars Company, Isfahan Science & Technology Town, Isfahan, Iran
3Department of Experimental Physics, Comenius University, Mlynska dolina F2, 84248, Bratislava, Slovak Republic

Abstract

Protonation, hydration, and cluster formation of ammonia, formaldehyde, formic acid, acetone, butanone, 2-ocatanone, 2-nonanone, acetophenone, ethanol, pyridine, and its derivatives were studied by IMS-TOFMS technique equipped with a corona discharge ion source. It was found that tendency of the protonated molecules, MH+, to participate in hydration or cluster formation depends on the basicity of M. The molecules with higher basicity were hydrated less than those with lower basicity. The mass spectra of the low basic molecules such as formaldehyde exhibited larger clusters of MnH+(H2O)n, while for compounds with high basicity such as pyridine, only MH+ and MH+M peaks were observed. The results of DFT calculations show that enthalpies of hydrations and cluster formation decrease as basicities of the molecules increases. Using comparison of mass spectra of formic acid, formaldehyde, and ethanol, effect of structure on the cluster formation was also investigated. Formation of symmetric (MH+M) and asymmetric proton-bound dimers (MH+N) was studied by ion mobility and mass spectrometry techniques. Both theoretical and experimental results show that asymmetric dimers are formed more easily between molecules (M and N) with comparable basicity. As the basicity difference between M and N increases, the enthalpy of MH+N formation decreases.

通过配备电晕放电离子源的IMS-TOFMS技术研究了氨,甲醛,甲酸,丙酮,丁酮,2-辛酮,2-壬酮,苯乙酮,乙醇,吡啶及其衍生物的质子化,水合和团簇形成。已发现质子化分子MH +参与水化或团簇形成的趋势取决于M的碱度。具有较高碱度的分子的水合程度低于具有较低碱度的分子的水合程度。低碱性分子(例如甲醛)的质谱表现出较大的M n H +(H 2 O)n簇,而对于高碱性的化合物(例如吡啶),只有MH +  和MH +观察到M个峰。DFT计算的结果表明,随着分子碱度的增加,水合焓和簇形成焓降低。通过比较甲酸,甲醛和乙醇的质谱,还研究了结构对团簇形成的影响。通过离子迁移率和质谱技术研究了对称的(MH + M)和不对称的质子结合二聚体(MH + N)的形成。理论和实验结果均表明,在具有相当碱性的分子(M和N)之间更容易形成不对称二聚体。随着M和N之间的碱度差增加,MH + N形成的焓降低。

Keywords: Proton affinity, Clustering, Hydration, Proton-bound dimer, Mass spectrometry

关键词:质子亲和力、团簇、水合作用、质子结合二聚体、质谱

 


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