| Abstract
| - 10-(2-Deoxy-β-d-ribofuranosyl)pyrimido[4‘,5‘:4,5]pyrimido[1,6-a]indole-6,9(7H)-dione (dCPPI) and itsderivatives were synthesized via the Suzuki−Miyaura coupling reaction of 5-iododeoxycytidine with5-substituted N-Boc-indole-2-borates and characterized by UV−vis and fluorescence spectroscopy. Thenew fluorescent nucleosides showed rather large Stokes shifts (116−139 nm) in an aqueous buffer. Thefluorescent intensities were dependent on the nature of the substituents on the indole rings. The electron-withdrawing groups increased the fluorescent intensity while the electron-donating groups having lonepairs decreased it. Among the substituted dCPPI derivatives tested, the trimethylammonium derivative ofdCPPI was found to emit the brightest fluorescent light. The solvatochromism of dCPPI and its derivativeswas also studied. Some of the dCPPI derivatives showed interesting solvent-dependent fluorescenceenhancement and could be useful as new fluorescent structural probes for nucleic acids. The Lippert−Mataga analyses of the Stokes shift were also carried out to obtain estimated values of the dipole momentof the excited states of some of the derivatives.
|
