Computational Analysis of Vinylbenzoic Acid Isomers for Predicting Remineralization Potential

Abstract

The conformations of stable calcium (Ca) ion complexes of three vinylbenzoic acid isomers (i.e., p-VBA, m-VBA, and o-VBA) and their reactivity toward Ca ion were investigated by computational approaches to investigate the remineralization potential of VBAs. The quantum chemistry CAChe software package was used for benchtop molecular design. Molecular mechanics (MM) calculations were used to determine the lowest steric energy structures of the VBAs and the VBA-Ca ion complexes. The steric energy of the m-VBA-Ca ion complex is larger than those obtained for complexes with p-VBA and o-VBA. The steric energy difference between the VBA-Ca ion complexes and the corresponding VBA (ΔE*) was obtained. The ΔE* of m-VBA was approximately 3–5 times higher than those of p-VBA and o-VBA. The energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of each VBA was obtained by molecular orbital (MO) calculations. p-VBA showed the lowest LUMO and HOMO energy levels, and their energy difference was very small compared with m-VBA and o-VBA. Comparing the energy differences between the LUMO of the Ca ion and the HOMO of the VBAs (ΔE**), p-VBA showed a slightly larger ΔE** than both m-VBA and o-VBA. Although no correlation was found between the ΔE* and ΔE**, it is suggested that o-VBA has a higher reactivity toward Ca ion due to its smaller ΔE* and ΔE**. Overall, it is suggested that the reactivity of VBAs toward Ca ion and their remineralization potential are influenced by the specific isomer of VBAs.