Host-guest interactions between cyclophane and arginine-methyl ester: A theoretical study

With the goal of understanding the supramolecular interactions between cyclophane and nitrogen-rich amino-acid with guanidinium group, we performed theoretical calculations in vacuum with neutral molecules. Since our future plans are to compare our theoretical results with the experiments, we designed a system composed of cyclophane with four pendant hexyl chains, which can dissolve in a nonaqueous media and arginine methyl ester, which has guanidinium group that can play an important role in the stabilization of the system. The conformational search and geometry optimizations were performed with the density functional theory functional B3LYP in conjunction with the 6-31G^∗ basis set. The results show that when the guanidinium group of the arginine methyl ester participates with a hydrogen bond or supramolecular interaction with the cycle, the dissociation energies tend to be lower than in the cases in which guanidinium group does not participate in the formation of the complex.