A Balance between van der Waals and Cation–π Interactions Stabilizes Hydrophobic Assemblies

Abstract

A thermally highly stable molecular self-assembly (nanocube) in water, the decomposition temperature of which is 415 K, was developed by designing a gear-shaped amphiphile (GSA) with an indented hydrophobic surface, even though the nanocube is stabilized only by van der Waals (vdW) and cation-π interactions as well as the hydrophobic effect. The introduction of an electron-donating substituent in one of the benzene rings of the GSA increased the decomposition temperature by 12 K, which is due to the stronger cation-π interactions between the benzene ring and positively charged pyridinium rings and tighter molecular meshing between the GSAs in the nanocube. The position of the substituent introduced in the benzene ring greatly affects the thermal stability of the nanocubes, and this indicates that both vdW (molecular meshing) and cation-π interactions are crucial for improving the thermal stability of the hydrophobic assemblies.

Studies of Halogen Bonding Induced by Pentafluorosulfanyl Aryl Iodides: A Potential Group of Halogen Bond Donors in a Rational Drug Design

“…In particular, aromatic iodides are of great interest due to the design of halogen bond donors activated by substitution with several electron-withdrawing substituents [6,7]; pentafluoro-iodobenzene [8,9] and 3,5-bis-nitro(NO 2 )-iodobenzene [10] are representative examples (Figure 1a). Besides, in these planar halogen bond donors, the intermolecular π−π charge-transfer [11], anion–π [12,13], cation–π [14,15], and lone pair–π [16,17,18,19] interactions are always competition for and/or form a combination with halogen bonding in molecular assemblies. These aspects make the design of halogen bond donors more elaborate, especially for applications in the rational design of drugs [20].…”

Recommended Values of the Viscosity in the Limit of Zero Density for R134a and Six Vapors of Aromatic Hydrocarbons as Well as of the Initial Density Dependence of Viscosity for R134a. Revisited from Experiment Between 297 K and 631 K

“…1b of Ref. [41], are not so different. In addition, the parameters of the 11-6-8 potential deduced from the measured viscosity coefficients (without extrapolation to the limit of zero density) and reported in 1982 (Ref.…”

“…The moment of inertia amounted to I = 503.0 g ⋅ mm 2 , whereas the upper and lower gaps b 1 and b 2 between oscillating and fixed disks were 1.10 mm. The quartz-glass suspension strands of the viscometers had a length and a diameter of 170 mm and about (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) μ m, respectively, resulting in a period in vacuo 0 at 298.15 K of 24.61 s and 24.33 s. The design principle for the viscometer was specified in Ref. [19].…”