Benzene expansion Janus GC base analogues: A detailed theoretical study

Abstract

Density Functional Theory (B3LYP) and Time Dependent Density Functional Theory (TD-B3LYP) computations have been used to investigate the electronic structural and optical properties of the newly designed benzene expansion Janus GC bases (J-GC1, J-GC2 and J-GC3), and the effect of water solution and base pairing also has been considered. The results show that the benzene expansion J-GC bases can pair with G and C simultaneously to form stable H-bonded WC base pairs. The lowest absorption and emission wavelengths of J-GC1¡¢J-GC2 and J-GC3 are red shifted compared with J-GC due to the increase of effective conjugation length with the introduction of benzene. The oscillator strengths of J-GC1¡¢J-GC2 and J-GC3 are similar. The water solution greatly influences the properties of the excited states and the first excitation and emission wavelength changes in the range of 16–65nm. The water solution can increase the oscillator strengths of the absorption and emission spectra. The TD-B3LYP method predicts that the lowest excitation of J-GC3:C and J-GC2:G are charge transfer states, while the other base pairs present local transitions on the J-GC base moieties. The first excitation wavelengths of these local transition base pairs change in the range of 6–18nm indicating that H-bonding interaction can influence the first excitation energy.