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Some rodlike organic molecules exhibit exceptionally high layered crystallinity when composed of a link between π‐conjugated backbone (head) and alkyl chain (tail). These molecules are aligned side‐by‐side unidirectionally to form self‐organized polar monomolecular layers, providing promising 2D materials and devices. However, their interlayer stacking arrangements have never been tunable, preventing the unidirectional arrangements of molecules in whole crystals. Here, it is demonstrated that polar/antipolar interlayer stacking can be systematically controlled by the alkyl carbon number n, when the molecules are designed to involve effectively weakened head‐to‐head affinity. They exhibit remarkable odd–even effect in the interlayer stacking: alternating head‐to‐head and tail‐to‐tail (antipolar) arrangement in odd‐n crystals, and uniform head‐to‐tail (polar) arrangement in even‐n crystals. The films show excellent field‐effect transistor characteristics presenting unique polar/antipolar dependence and considerably improved subthreshold swing in the polar films. Additionally, the polar films present enhanced second‐order nonlinear optical response along normal to the film plane. These findings are key for creating polarity‐controlled optoelectronic materials and devices. [ABSTRACT FROM AUTHOR]

Solvate ionic liquids (SILs) composed of glymes and Li salts are potential electrolyte materials for Li ion batteries. Safety and durability of SIL‐based batteries can be realized by competing characters of solvate cations. Solvate structure of Li+ should be stable in the bulk to be nonvolatile, and its desolvation should occur rapidly on electrode surfaces which is considered as a rate‐limiting step in charging or discharging. To investigate such characters, potential‐dependent interfacial structure of [Li(G4)][TFSA], equimolar mixture of tetraglyme and lithium bis(trifluoromethanesulfonyl)amide, on an Au electrode has been investigated at the molecular scale by using surface‐enhanced infrared absorption spectroscopy. Despite discrete solvate ion [Li(G4)]+ is stable in the bulk, partial desolvation of Li+ on the electrode was observed at around the potential of zero charge, much more positive than Li+ reduction reactions. The driving force of the partial desolvation can be ascribed to the breaking of isotropic dielectric environment in the vicinity of the electrode, where image charge induced on the electrode surface stabilizes the partially desolvated structure enabling shorter Li+‐electrode distance. [ABSTRACT FROM AUTHOR]

A series of donor-acceptor p-nitro-p'-alkoxy (OR) substituted (E,E,E)-1,6-diphenyl-1,3,5-hexatrienes were prepared and their properties and crystal structures investigated. The flouresence spectra of these crystals were red-shifted relative to those for the solutions in low polar solvents, which can be attributed to the planarization of molecules in the solid state and to the strong intermolecular interactions in crystals.

The quantitative information on the formation on ionic aggregates in room-temperature Ionic Liquids (RTILs) based on the ratios of molar conductivity values ([A.sub.imp]/[A.sub.NMR], where [A.sub.imp] is the molar conductivity obtained by electrochemical impedance measurements and [A.sub.NMR] is that calculated from the pulse-field-gradient spin-echo NMR (PGSE-NMR) ionic self-diffusion coefficients and the Nernst-Einstein equation is reported. A decrease in ([C.sub.eff]) effective ionic concentration of the RTILs is well correlated with the normal boiling point and distillation rate, whereas the liquid-state dynamics is controlled by a subtle balance between the electrostatic and other intermolecular forces.

The CCSD(T) level interaction energies of CH/pi complexes at the basis set limit are estimated. The weak directionality has indicated that the hydrogen atom of the interacting C-H bond is not essential for the attraction and that the typical CH/pi interaction does not play a key role in determining the molecular orientation in molecular assemblies.

A series of room-temperature ionic liquids (RTILs) were prepared with different cationic structures, combined with an anion and the thermal property, density, self-diffusion coefficients of the cation and anion, viscosity, ionic conductivity were measured over a wide temperature range. It was found that the relative cationic and anionic self-diffusion coefficients for the RTILs appear to be influenced by the shape of cationic structure and that the microscopic ion dynamics and ionic state significantly contributes to the macroscopic physicochemical properties of the ionic liquids.

The ARS-E model was used for calculating the intermolecular interaction energy of hexafluorobenzene-benzene. The largest and most negative energy of -5.38 kcal/mol was observed in the slipped-parallel complex.

Single crystal of a series of (Z,E,Z)-1,6-diphenylhexa-1,3,5-triene 4,4'-dicarboxylic acid dialkyl esters that were prepared and their crystal structures and photoisomerization behaviors that were systematically investigated is described. The conformational flexibility of the alkyl chains made the large change in the trienegeometry in the lattice possible, leading to the enhancement of the photoreactivity in the crystalline state.

The interaction energies of the alkaline-earth-metal dication/benzene complexes were calculated at the MP2 level using the 6-311G-basis set. The calculations of benzene under an electric field show that the electric field produced by the diction is a cause of the C-C bond elongation in the alkaline-earth-metal dication/benzene complexes.

Calculation of intermolecular interaction energies of 14 orientation CHF3 dimers is done with electron correlation correction by the MP2 method. Electron correlation correction increases the attraction considerably, which indicates that the dispersion interaction is important for the attraction.

High-level ab initio calculations have been used to investigate the torsional potentials of methoxy and hydroxyl groups of omichron-hydroxyanisole. It was established that the intramolecular bond significantly stabilizes the energy minimum structure.

Estimation of the intermolecular interaction energies has been carried out by means of ab initio calculations of C (sub)2 H (sub)4 - CH (sub)4 and C (sub)2 H (sub)6 - CH (sub)4 dimer orientations. The role of the electrostatic, dispersion and charge transfer interactions between aliphatic C-H bond and pi-system has been discussed.

Two medium-size basis sets, aug(d,p)-6-311G** and aug(df,pd)-6-311G**, are developed to analyze the dispersion interactions of hydrocarbon molecules. Intermolecular interaction energies of methane, ethane, propane, ethylene, acetylene and benzene dimers calculated with the basis sets are compared with those from the Sadlej's basis set and Dunning's correlation-consistent basis sets. Results show that the aug(d,p)-6-311G** set is more effective than Sadlej's basis set in evaluating dispersion energy. The aug(df,pd)-6-311G** basis set is also smaller than Dunning's basis sets.

Ab initio methods using basis sets of up to 6-311G(2d) quality, with MP2 level electron correlation energy correction were used to examine the intermolecular interaction potential of the corannulene dimer in a parallel (D5h) orientation. Results indicate that the dispersion interaction is the dominant principle in the interaction of the corannulene dimer. Findings also suggest that the intermolecular interaction potential obtained from the corannulene dimer will outperform atom-atom potentials for molecular dynamics studies of the bulk properties of fullerenes.

The role of neutral species and metal coordination in the enzymatic cleavage of RNA have been investigated. The results showed that the cleavage occurs via a cyclic pentacoordinate oxyphosphane intermediate/transition state. The metal coordination produces an electrostatic field that allows in-line attack and departure process. This also prevents pseudorotations for the positional exchanges of ligands of pentacoordinate oxyphosphorane intermediate/transition state.

Studies of oxyphosphoranes such as neutral pentahydroxyphosphorane, dianionic trihydroxyphosphorane and trimethoxyphosphorane suggest that conformation of the P-O3 bond and its effect on reactivity are in accord with stereoelectronic effect-based predictions. The 'n-sigma asterisk interaction' is not crucial for the stereoelectronic control of the oxyphosphorane system.