Gas phase chemistry of some biologically relevant molecules

Mass spectrometers offer an ideal 'chemical laboratory' for the study of the intrinsic ionic reactions in the gas-phase. They provide a milieu where reactions can be studied without the interference of solvents and counterions usually present in solution. In the recent years, mass spectrometry (MS), in particular electrospray ionisation mass spectrometry (ESI/MS), was shown to be a powerful tool in the study of biomolecules and their non-covalent interactions. More recently, with the advancement in computing, theoretical chemistry calculations are playing a bigger role in studying the structures, energetic and mechanisms of reactions studied in the gas phase. These calculations are essential to help interpret and understand the observations made during mass spectrometry studies.

In this presentation, we will briefly introduce and emphasize the role and results of some electronic structure calculations used in our group. Thus, results from two projects will be presented: (i) DFT calculations on the structures and fragmentation reactions of the betaines (CH₂)₂S(CH₂)_nCO₂ (n =1,2); and (b) Molecular Dynamics simulation results used to gain insights into the observation of 'magic numbers' in the clusters of [Pt(L)(dG)_n]²⁺ (L = terpyridine or diethyltriamine) upon reaction of Pt(L)²⁺ with deoxyguanosine (dG).