FT-IR and 1H NMR spectroscopic evidence of sugar ring conformational change in NH 4GpG on complexation to form cis-[Pt(NH 3) 2(GpG)] +

Abstract

The conformational change of the ribose ring in NH 4GpG and cis-[Pt(NH 3) 2(GpG)] + was confirmed by FT-IR spectroscopic evidence as being C2′- endo, C3′- endo, anti, gg sugar ring pucker in the solid state. These results were compared with 1H NMR spectral data in aqueous solution. The FT-IR spectrum of NH 4GpG shows marker bands at 802 cm −1 and 797 cm −1 which are assigned to the C3′- endo, anti, gg sugar-phosphate vibrations of ribose (−pG) and ribose (Gp−), respectively. The FT-IR spectrum of cis-[Pt(NH 3) 2(GpG)] + (with N7N7 chelation in the GpG sequence) shows a marker band at 800 cm −1 which is assigned to the C3′- endo, and a new shoulder band at 820 cm −1 related to a C2′- endo ring pucker. The ribose conformation of (−pG) moiety in NH 4-GpG, C3′- endo, anti, gg changes into C2′- endo, anti, gg when a platinum atom is chelated to N7N7 in the GpG sequence.