Gas phase supramolecular cluster ions of deoxyguanosine induced by binding to (2,2′:6′2″-terpyridine)-platinum(II) and (diethylenetriamine)-platinum(II)

Abstract

Electrospray ionization (ESI) of solutions containing deoxyguanosine (dG) and tridentate platinum chloride complexes yields clusters of general formula [Pt^II(L)(dG)_n]²⁺, where L = 2,2′:6′,2″ terpyridine (terpy), or diethyltriamine (dien). When these clusters were mass selected and subjected to collision induced dissociation (CID), the primary fragmentation channels arise from loss of dG and protonated dG to yield the fragment ions [Pt^II(L)(dG)_n−x]²⁺ and [Pt^II(L)(dG)_n−x-H]⁺ respectively. The relative abundances of the [Pt^II(L)(dG)_n−x]²⁺ fragments depend on the nature of the ligand, L. The most abundant peaks observed were: n−x = 5 for terpy and n−x = 4 for dien. In order to further understand these gas phase reactions, molecular dynamics calculations were carried out. These simulated collision calculations not only predict with fidelity the experimental profiles for the relative abundances for the [Pt^II(L)(dG)_n−x]²⁺ fragments, for both terpy and dien ligand systems, but they also provide structural insights into the complex interplay of hydrogen bonding and stacking interactions within these clusters.