Kikuko Iida

Bio: Kikuko Iida is an academic researcher from Tokyo University of Agriculture and Technology. The author has contributed to research in topics: Hydrogen bond & Crystal structure. The author has an hindex of 1, co-authored 5 publications receiving 4 citations.

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

Abstract: 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 dnorm 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.

Crystal structure and Hirshfeld surface analysis of 2-hy-droxy-7-meth-oxy-1,8-bis-(2,4,6-tri-chloro-benzo-yl)naphthalene

Abstract: In the title compound, C25H12Cl6O4, the two carbonyl groups are oriented in a same direction with respect to the naphthalene ring system and are situated roughly parallel to each other, while the two 2,4,6-tri­chloro­benzene rings are orientated in opposite directions with respect to the naphthalene ring system: the carbonyl C—(C=O)—C planes subtend dihedral angles of 45.54 (15) and 30.02 (15)° to the naphthalene ring system are. The dihedral angles formed by the carbonyl groups and the benzene rings show larger differences, the C=O vectors being inclined to the benzene rings by 46.39 (16) and 79.78 (16)°. An intra­molecular O—H⋯O=C hydrogen bond forms an S(6) ring motif. In the crystal, no effective inter­molecular hydrogen bonds are found; instead, O⋯Cl and C⋯Cl close contacts are observed along the 21 helical-axis direction. The Hirshfeld surface analysis reveals several weak interactions, the major contributor being Cl⋯H/H⋯Cl contacts.

Crystal structure of 1,2-bis­(4-fluoro­phen­yl)-1-hy­droxy-2,3,8-tri­meth­oxy­acenaphthene: formation of a five-membered intra­molecular O—H⋯O hydrogen-bonded ring

Abstract: The structure of the title compound, C27H22F2O4, at 193 K has triclinic (P\overline{1}) symmetry. The hy­droxy and meth­oxy groups at the 1,2-positions of the acenaphthene core display a cis configuration. Both substituents are involved in the formation of a five-membered intra­molecular O—H⋯O hydrogen-bonded ring. The 4-fluoro­phenyl rings make dihedral angles of 87.02 (7) and 51.86 (8)° with the naphthalene ring system. In the crystal, a pair of non-classical C—H⋯O hydrogen bonds forms centrosymmetric dimeric structures. The dimeric aggregates are linked in the ac plane through non-classical C—H⋯F hydrogen bonds and C—H⋯π interactions.

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

Abstract: 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 dnorm 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.

Packing structure and non-classical hydrogen bonding interactions of the toluene solvate crystal of 1,8-bis(4-methylbenzoyl)naphthalene-2,7-diyl dibenzoate: Role of toluene molecule in determination of the spatial arrangement of the major constituent molecules

Abstract: Abstract The toluene solvate crystal of the titled highly congested aromatic ketone-ester compound has been subjected to crystal structural analysis from the viewpoints of the clarification of distribution feature of effective non-classical hydrogen bonds and the retention and perturbation of the symmetric nature. The two independent molecules of the title naphthalene derivative, which bears two aroyl groups at the adjacent inner positions and two benzoyloxy groups at the neighboring β-positions, and one disordered solvent toluene molecule are incorporated in the asymmetric unit of P21 /c (Z′= 2). In the packing of the solvate crystal, the solvent toluene molecule plays the multi roles of hydrogen donor/acceptor for C–H…π non-classical hydrogen bonds and hydrogen donor for C–H…O = C ones. On the other hand, the role of other benzene rings of the parts of the title compound molecules is confined. The 4-methylbenzoyl groups situated at the molecular inner positions mainly play the role of the hydrogen donor of C–H…π non-classical hydrogen bond. The benzoyloxy groups that extend outward from the molecular body mainly act as the hydrogen acceptors of C–H…O and C–H…π non-classical hydrogen bonds. The naphthalene ring moderately contributes as the hydrogen acceptor for C–H…π non-classical hydrogen bonds and as the hydrogen donor for C–H…O non-classical hydrogen bonds. The roles of the toluene molecule are not limited to a simple filler for the void among the major constituent molecules but proved to position at the pseudo-centrosymmetric center of the counter-configurated pair of molecules of the independent major component compounds to concentrate the effective non-classical hydrogen bonds.

Weak interaction based interpretation of crystal packing characteristics of aromatic rings accumulating molecules: Hirshfeld surface analyses reinforced X-ray crystal study on 1,8-dibenzoyl-7-ethoxynaphthalen-2- ol and its 2-ethoxylated homologue

Abstract: Abstract The molecular vicinity characteristics in the crystal of two dibenzoylnaphthalene derivatives having intimately similar molecular formula with solely one substituent difference, 2-hydroxy group or 2-ethoxy one, were comparatively investigated in relation to the types of weak interactions with the aid of X-ray crystal structural study reinforced by Hirshfeld surface analyses and two-dimensional plotting of the normalised interatomic distance crossing the molecular surface. The general X-ray crystal structural analysis has selected the effective non-covalent bonding intra/intermolecular interactions as the governing interactions for the molecular packing on the basis of short interatomic distances. The minute spatial structure around respective interaction demonstrates the characteristics of the non-covalent bonding interatomic interactions. The general X-ray crystal structural analysis also reveals the relationship between the whole crystalline symmetricity and the fashion of the interactions. The Hirshfeld surface analysis displays the location of the short contacts on the molecular surface. The two-dimensional plotting reveals the contribution of the interacting atomic pairs covering the molecular surfaces as the geometrical distribution of the effective intermolecular non-covalent bonding interactions. The difference in the revealed packing features and whole proximity for two compounds are rationally interpreted according to the strength categorization of the non-covalent bonding interactions especially in relation with the proportional/disproportional distribution of the molecular contact index. The comparison illustrates the superior intermolecular interaction concentrates the short interatomic distances and strain at the specified region of the molecular aggregate resulting in arise of satisfactory flexibility of the extroverted sides to realise highly symmetrical interactions.