Historical Perspectives in the Study of Ion Chemistry by Mass Spectrometry: From the Gas Phase to Solution

Abstract

Mass spectrometry (MS), originally developing from nineteenth-century physics, has a history dating back more than a hundred years. Since then, the technique has advanced enormously. The advent of new methods of ion production, novel mass analyzers, and new tools for data processing has made it possible to analyze almost all chemical entities, ranging from small organic compounds to large biological molecules and whole living cells/tissues. Today, mass spectrometry has become one of the most powerful and popular modern physical-chemical methods to study the details of elemental and molecular processes in nature. Because of its unparalleled capability of providing information on molecular weight, chemical structures, isotopic content, and even molecular dynamics, mass spectrometry is playing an increasingly significant role in the chemical and life sciences. As a traditional analytical tool and a booming technology for biomedicine, it has found extensive applications in nearly every discipline involving chemical analysis such as petroleum prospecting and refining, food processing, drug discovery, metablomics, genomics, proteomics and structural biology, as well as the environment, public safety, and industrial process monitoring. Along with the development of mass spectrometric technology, the chemistry of gaseous ions has been explored by the study of unimolecular and collision-induced dissociation (CID) [1][2][3][4] and by the study of ion/molecule reactions [2,[5][6][7][8][9][10][11][12][13][14][15][16][17] and ion/ion reactions [18][19][20][21][22][23][24][25][26] in the gas phase. The study of gas-phase ion chemistry has both fundamental and practical significance because it not only provides diverse information on ion reactivity, thermochemistry, and dynamics, but it also forms one basis for chemical analysis using mass spectrometry. In addition, the ion reactivity examined in the isolated gas-phase environment of mass spectrometers has a strong connection with reaction chemistry in solution, as well as contrasting with it. Many important ionic intermediates which are hard to probe in the condensed phase can be easily accessed in the gas phase. Therefore, mass spectrometry has also become an important and unique tool for the mechanistic investigation of organic reactions (particularly organometallic reactions), since soft electrospray ionization (ESI) technology [27, 28] became available. In this regard, there is a large body of work in the literature, which is reviewed in this book. j37This chapter will provide an overview of the history and the current state of the art of mass spectrometry-based study of ion chemistry, specifically of ion/molecule reactions. As this is a broad topic with an immense literature (over 15 000 papers), our emphasis will be placed on the applications of ESI-MS coupled with gas-phase ion/ molecule reactions and tandem mass spectrometry in organometallic chemistry, including probing key intermediates and reaction pathways of organometallic reactions in solution. We will start with...