Tuning the gas phase redox properties of copper(II) ternary complexes of terpyridines to control the formation of nucleobase radical cations.

摘要: Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary copper(II) complexes [Cu(terpyX)(M)]2+ (where terpyX = is a substituted 2,2′:6′,2″-terpyridine ligand; M the nucleobases: adenine, guanine, thymine and cytosine) was examined as means forming radical cations nucleobases in gas phase. The following substituents were examined: 4′-NMe2-2,2′:6′,6″-terpyridine; 4′-OH-2,2′:6′,6″-terpyridine; 4′-F-2,2′:6′,6″-terpyridine; 2,2′:6′,6″-terpyridine; 4′-Cl-2,2′:6′,6″-terpyridine; 4′-Br-2,2′:6′,6″-terpyridine; 4′-CO2H-2,2′:6′,6″-terpyridine; 4′-NO2-2,2′:6′,6″-terpyridine 6,6″-dibromo-2′,2:6′,2″-terpyridine. Each selected subjected to collision induced dissociation (CID) quadrupole ion trap. types fragmentation reactions observed for these depend on nature substituent terpyridine ligand, while yields follow order their energies (IEs): G (lowest IE) > A C T (highest IE). In general, cation formation favoured electron withdrawing (e.g. NO2) loss neutral nucleobase donating NMe2). Loss protonated major pathway OH system, consistent with its ability bind metal centre deprotonated ligand. Crystal structure determinations (6,6″-dibromo-2′,2:6′,2″-terpyridine)bis(nitrato)copper(II) diaqua(4′-oxo-2,2′:6′,6″-terpyridine)copper(II) nitrate monohydrate performed correlated ESI results.