臺灣博碩士論文加值系統

本篇論文的主旨在於提出新的離子團簇光譜學的研究方法，以振動預解離式紅外光譜分析結合高階理論計算的方式，用於研究複合離子團簇氣相中的結構和動力學行為。研究主題包含了分子間疏水性作用力（hydrophobic interaction），二元溶劑中質子競爭機制（competitive proton solvation by solvents），含Peptide鍵分子的水合及水解機制（hydrolysis/hydration of the peptide analogue），以及離子分子的氣相泛頻光譜研究（the first overtone spectroscopy of ionic cluster）。
研究中所使用的儀器條件，雷射系統，及所使用的理論計算參數，我們在論文的第一章有清楚的描述，其他各個章節中，我分別用來敘述前段摘要所提到的各項研究主題。第二章中我們提出了四個例子，藉由電荷增強作用來觀察到分子間疏水性作用力對結構的影響。此外我們也發現分子團簇的內能，對於預解離式紅外光譜有極關鍵性的影響。第三章中我們專注於討論二元溶劑中質子轉移及質子競爭機制。由紅外光光譜的結果中，我們推論出除了離子團簇的大小，離子團簇的結構也會影響質子在二元溶劑溶劑中行為表現。第四章中我們藉由研究formamide分子的質子化過程，來討論含Peptide鍵分子的質子化機制。紅外光光譜及理論計算的結果都證實Peptide鍵上的氧原子是質子化的優先位置，而不是氮原子。水合作用於團簇的結果也證實了氧原子是質子化的優先位置，團簇中水分子的數量大於等於三時，質子開始有機會由氧原子轉移到水分子上。在第五章中我們延續上章的主題，我們另外探討了水合作用是如何地改變多Peptide分子的結構。我們選擇含有兩組官能基的鍊狀分子為研究目標，利用理論計算及光譜來分析水分子在結構變化上所扮演的角色。最後一章中我們發表第一次氣相中離子分子團簇的泛頻紅外光光譜的研究結果。由於分子位於泛頻紅外光波長的吸收強度較基頻弱100倍，到目前為止只有發表了少數的光譜結果。我們成功的得到H+(H2O)n及H+(CH3OH)m的遠紅外光波長範圍的光譜，並推導出各分子的簡諧頻率及非簡諧係數。

This thesis depicts new experimental investigations of mass-selected mixed cluster ions, produced under supersonic expansion conditions of using a vibrational predissociation ion trap spectrometer equipped with a corona discharge ion source and coupled with an infrared laser system. Density functional theory calculations are performed at B3LYP/6-31+G* level to assist interpretation of the spectra. The combined investigation provides information on structure and proton transfer dynamics of ionic clusters in the gas phase. Subjects studied include hydrophobic interactions, competitive proton solvation by solvents, hydrolysis/hydration of the peptide analogue, and the first overtone spectroscopy of ionic clusters.
The experimental layout of the vibrational predissociation ion trap (VPIT) spectrometer and involved parameters in the calculations using density functional theory (DFT) are described in Chapter One. A description of the notations used throughout this work is given therein. Chapter Two illustrates proton assisted hydrophobic interactions in the gas phase. Four modeling coumpounds, (CH3)2O dimer, (CH3)(C2H5)O dimer, CH3C(O)CH3 dimer, and CH3C(O)H dimer, with single protonated water molecule are investigated by infrared spectroscopy under various beam conditions.
In Chapter Three, the behavior of the excess proton (H+) in binary solvent is closely examined. Proton competition between methanol and water sheds insight into anomalous high proton conductivity in solution. Chapter Four characterizes the hydration/hydrolysis of peptide-containing molecule (formamide) by both infrared and mass spectroscopy. First infrared spectroscopic evidence of O-protonation rather than N-protonation of protonated mixed formamide clusters is found, which is in line with the prediction from the amide resonance model. Acid-assisted hydration of CH3C(O)CH2C(O)CH3 , the peptide chain analogue, is inspected in Chapter Five. Water-bridged conformation, either H3O+-bridged or H5O2+-bridged structure, is produced under various supersonic beam conditions. In all the mixed water cluster ions, both the sample-centered and the H3O+-centered isomers are identified on the basis of both experimental observations and theoretical calculations. Proton pulling effects have been discussed in these modeling systems.
The first overtone spectroscopy of protonated water and methanol complexes is demonstrated in Chapter Six. Although there have been a number of publications for overtone spectroscopy of single molecule and neutral complexes, there are only few investigations on overtone spectroscopy of ionic clusters. We present in this chapter the first spectroscopic identifications and derive harmonic frequencies and anharmonic coefficients of the OH stretches in H+(H2O)3-5, and H+(CH3OH)4 from their first overtone and combination bands in the near infrared region using a tunable optical parametric oscillator (OPO) laser system.

Table of Contents
Abstract……………………………………………………………………1
Acknowledgments……………………………………………………………4
Chapter One
Studies of Cluster Ions: An Overview
I. Introduction……………………………………………………………5
II. Methodologies…………………………………………………………6
A. Vibrational predissociation spectroscopy
B. Ab initio Calculations
C. Vibrational predissociation ion trap (VPIT) spectrometer
III. Abbreviations and assignments…………………………………14
References…………………………………………………………………16
Figures……………………………………………………………………17
Chapter Two
Proton-Assisted Hydration at the Hydrophobic Sites of Ether and Ketone Dimer
I. Introduction…………………………………………………………22
II. Results and analysis: …………………………………………23
A. H+[(CH3)2O]2H2O & H+[(CH3)(C2H5)O]2H2O
B. H+[(CH3C(O)CH3)]2H2O & H+[(CH3C(O)H)]2H2O
III. Discussion…………………………………………………………26
IV. Summary………………………………………………………………28
References………………………………………………………………29
Figures……………………………………………………………………32
Chapter Three
Behavior of the Excess Proton in H+(CH3OH)m(H2O)n
I. Introduction…………………………………………………………43
II. Theoretical analysis……………………………………………45
III. Results and discussion………………………………………45
A.Hydration of protonated methanol monomer
B.Competitive proton solvation by binary solvents
IV. Summary………………………………………………………………57
References………………………………………………………………59
Figures……………………………………………………………………66
Chapter Four
Characterization of Protonated Formamide-Containing Clusters
I. Introduction……………………………………………………………79
II. Results and analysis………………………………………………81
A. Protonation site of formamide
B. Hydration of protonated formamide
III. Summary………………………………………………………………89
References…………………………………………………………………91
Figures……………………………………………………………………102
Chapter Five
Hydration-Induced Conformational Change of a Bifunctional Ion
I. Introduction…………………………………………………………114
II. Results and analysis……………………………………………115
III. Summary……………………………………………………………122
References………………………………………………………………124
Figures……………………………………………………………………129
Chapter Six
The First Overtone Spectroscopy of Ionic Clusters in the Gas Phase
I. Introduction…………………………………………………………135
II. Results and analysis……………………………………………137
(1) H+(H2O)n , n=3-5
(2) H+(CH2OH)4
III. Discussion…………………………………………………………140
IV. Summary………………………………………………………………143
References………………………………………………………………145
Figures……………………………………………………………………152

References
1, Calvin, M. Chemical Evolution. Clarendon Press, Oxford. 1969.; Miller, S. L. J. Amer. Chem. Soc. 1954, 77, 2351-2361.: Alberts, B.; Bray, D.; Lewis, J. Molecular Biology of the Cell. 3rd ed. Garland Publishing, New York and London. 1994.
2, Wakisaka, A.; Abdoul-Carime, H. Yamamoto, Y.; Kiyozumi, Y. J. Chem. Soc., Faraday Trans. 1998, 94, 369.
3, See, for example, Vollhardt, K. P.; Schore, N. E. Organic Chemistry, Freeman, New York, 1995, pp. 277-286.
4, Hunter, E. P. L.; Lias, S. G. J. Phys. Chem. Ref. Data, 1998, 27, 413 .
5, Chang, H.-C.; Jiang, J. C.; Hanhndorf, I; Lin, S. H.; Lee, Y. T.; Chang, H.-C. J. Am. Chem. Soc., 1999, 121, 4443 .
6, Soper, A. K.; Finney, J. L. Phys. Rev. Lett., 1993, 71, 4346
7, Kebarle, P.; Haynes, R. N.; Collins, J. G. J. Am. Chem. Soc., 1967, 89, 5753
8, Hernández-Cobos, J.; Ortega-Blake, I. J. Chem. Phys.,1995, 103, 9261
9, Wu, C.-C.; Jiang, J. C.; Boo, D. W.; Lin, S. H.; Lee, Y. T.; Chang, H.-C. J. Chem.Phys., 2000, 112, 176.
10, Price, J.M., Ph.D. Thesis, University of California, Berkeley, CA, 1990. Chapter 2.
11, Meot-Ner, M., J. Am. Chem. Soc., 1986, 108, 6189-6197.
12, Jiang, J.C., Wang, Y.S., Chang, H.-C., Lin, S.H., Lee, Y.T., Niedner-Schatteburg, G., and Chang, H.-C., J. Am. Chem. Soc., 2000, 122 (7), 1398-1410
13, Chang, H.-C., Jiang, J. C., Chang, H.-C., Wang, L. R., and Lee, Y. T., Israel J. Chem., 1999, 39 (3-4), 231-243.
14, Jordan, K. D., and Christie, R. A., J. Phys. Chem. B., 2002,106, 8376-8381.
15, Marcus, Y., Ion solvation; A Wiley-Interscience publication: New York, 1985.
16, Chang, H.-C., Wang, Y. S., Lee, Y. T., and Chang, H.-C. Int. J. Mass. Spectrom., 1998,1781, 4443-4450
17, Chang, H.-C., Jiang, J.C., Lin, S.H., Lee, Y. T. and Chang, H.-C. J. Phys. Chem. A, 1999, 103 (16), 2941-2944.
18, Moet-Ner, M., J. Am. Chem. Soc., 1984, 106, 1265.