DFT study of stability and electronic properties of cyclic tetramer involving dinucleobase monomers, comprising acetylene central block substituted at both edges with guanine and cytosine nucleobases

Abstract

The dinucleobase molecule comprising acetylene central block substituted at both edges with guanine and cytosine nucleobases has previously been synthesised. In this manuscript, the stability and electronic properties of cyclic tetramer involving this ethynylene-linked molecule are theoretically investigated at B3LYP/6-311++G(d,p) level. In addition to gas phase, the influence of aprotic solvents on the stability and electronic properties of cyclic tetramer is also investigated with a focus on its dielectric constant. Here, toluene, diethyl ether, tetrahydrofuran, dichloromethane, acetophenone, acetone, benzonitrile, propanonitrile and acetonitrile are chosen as aprotic solvent. It is observed that the stability of cyclic tetramer is diminished by increasing the dielectric constant of solvent. Whereas the cyclic tetramer is stabilised by hydrogen bonds, the strength and nature of hydrogen bonds are examined using AIM analysis. The relationships between dielectric constant of solvent and some electronic properties of cyclic tetramer such as band gap, electron affinity, electrophilicity index, first ionisation energy, electronic chemical potential, chemical softness and hardness are also investigated.