Theoretical design and rotational conformation analysis of molecular bevel gear with triptycene as rotator

Abstract

A molecular bevel gear with triptycene as the rotator and naphtha[2,1,8-def]isoquinoline as the stator was designed, and the rotational process and conformational transformation of the gear were calculated and analyzed by density functional theory. To be specific, the rotational potential energy surface was investigated via scanning the dihedral angle θ (H71‒N67‒C1‒C5). The geometry optimization was performed at the M06-2X level in conjunction with def-TZVP basis set. According to the correlation between the two rotors, the rotation mode of gear can be defined as gear rotation and gear slippage. And the rotational energy barrier indicated that the gear rotation was easier than gear slippage. For transition-state and ground-state structures, the single-point energy and thermodynamic correction were calculated at M06-2X/def2-TZVP levels. The C2 conformations in ground state achieved its stable structure owing to intramolecular hydrogen bonding, C‒H···π, and π···π stacking interactions. In order to gain insight into the intramolecular interaction, the noncovalent interactions based on the reduced density gradient method and Bader’s atoms in molecules theory were analyzed in detail.