Distinguishment of Weak Interactions of Hydrogen Atoms Bound to Carbon Atoms: X-Ray Crystal Structural and Hirshfeld Surface Analyses of 2- Hydroxy-7-methoxy-3-(2,4,6-trimethylbenzoyl)naphthalene with the 2- Methoxylated Homologue

Title:Distinguishment of Weak Interactions of Hydrogen Atoms Bound to Carbon Atoms: X-Ray Crystal Structural and Hirshfeld Surface Analyses of 2- Hydroxy-7-methoxy-3-(2,4,6-trimethylbenzoyl)naphthalene with the 2- Methoxylated Homologue

Volume: 19 Issue: 9

Author(s): Kikuko Iida, Toyokazu Muto, Miyuki Kobayashi, Hiroaki Iitsuka, Kun Li, Noriyuki Yonezawa*Akiko Okamoto*

Affiliation:

• Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology, 2-24-16, Nakamachi, Koganei, Tokyo 184-8588, Japan
• Japan Association for Working Environment Measurement, 6th floor, Mita Roudou Kijun Kyoukai Bldg, 4-4-5, Shiba, Minato-ku, Tokyo 108-0014, Japan

• Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology, 2-24-16, Nakamachi, Koganei, Tokyo 184-8588, Japan

Keywords: Non-coplanarly accumulated aromatic rings, weak interactions, Hirshfeld surface analysis, classical hydrogen bonds, nonclassical hydrogen bonds, H…H interactions.

Abstract: X-ray crystal and Hirshfeld surface analyses of 2-hydroxy-7-methoxy-3-(2,4,6- trimethylbenzoyl)naphthalene and its 2-methoxylated homologue show quantitatively and visually distinct molecular contacts in crystals and minute differences in the weak intermolecular interactions. The title compound has a helical tubular packing, where molecules are piled in a two-folded head-to-tail fashion. The homologue has a tight zigzag molecular string lined up behind each other via nonclassical intermolecular hydrogen bonds between the carbonyl oxygen atom and the hydrogen atom of the naphthalene ring. The d_norm index obtained from the Hirshfeld surface analysis quantitatively demonstrates stronger molecular contacts in the homologue, an ethereal compound, than in the title compound, an alcohol, which is consistent with the higher melting temperature of the former than the latter. Stabilization through the significantly weak intermolecular nonclassical hydrogen bonding interactions in the homologue surpasses the stability imparted by the intramolecular C=O…H–O classical hydrogen bonds in the title compound. The classical hydrogen bond places the six-membered ring in the concave of the title molecule. The hydroxy group opposingly disturbs the molecular aggregation of the title compound, as demonstrated by the distorted H…H interactions covering the molecular surface, owing to the rigid molecular conformation. The position of effective interactions predominate over the strength of the classical/nonclassical hydrogen bonds in the two compounds.

Cite this article as:

Iida Kikuko, Muto Toyokazu, Kobayashi Miyuki, Iitsuka Hiroaki, Li Kun, Yonezawa Noriyuki*, Okamoto Akiko*, Distinguishment of Weak Interactions of Hydrogen Atoms Bound to Carbon Atoms: X-Ray Crystal Structural and Hirshfeld Surface Analyses of 2- Hydroxy-7-methoxy-3-(2,4,6-trimethylbenzoyl)naphthalene with the 2- Methoxylated Homologue, Letters in Organic Chemistry 2022; 19 (9) . https://dx.doi.org/10.2174/1570178619666211231105233