하나의 asymmetric unit에 2개의 분자가 들어있는 결정구조에서 파이-파이 스태킹 효과 분석 = Effect of p-p stacking interactions in the crystal packing of the molecules with two molecules in asymmetric unit

다국어 초록 (Multilingual Abstract)

DNA is one of the most stable molecule in the living system. One of the main contributions of this stability
is from the p-p stacking interactions between heterocyclic bases with aromatic characters. We recently
determined the co-crystal structure of 2-(2-(4-hydroxy-3-methoxyphenyl)vinyl)-1,3-dimethyl benzimidazolium
with naphthalene-2-sulfonate(HMB-NS) which interacts with the benzimidazolium cation by O–H…O hydrogen
bonding to form an ionic pair. It has two molecules in asymmetric unit, and the difference of two structure
is on the dihedral angle between phenyl and benzimidazolium ring. The crystal packing of this structure
shows alternative stacking conformation between phenyl and benzimidazolium ring, which indicate that the
main determinant of two different configured molecules in asymmetric unit is the crystal packing effect with p-p stacking interactions. We investigate Cambridge Crystallographic Database for supporting the determinant
of two different molecules in asymmetric unit with methoxyphenyl-vinyl moiety and benzimidazolium moiety.
We found 14 related crystal structures with two molecules in asymmetric unit and most of cases show
strong p-p intermolecular stacking interactions in the crystal packing by the Hershfeld analysis. These
results indicate that the p-p stacking interactions are very important determinant in crystal packing for two
molecules in asymmetric unit