Phenyl group interactions

The observed enantioface differentiation in the reduction of the phenyl alkyl ketones was rationalized by postulating a 6-membered ring transition state for hydride transfer (Scheme 10). The transition state leading to the (S)-carbinol has an axial phenyl group interacting sterically with the binaphthoxy oxygen. 

Different types of van der Waals interactions are observed in the complexes. Hydrogen bonds formed between the ammonium Hn atoms and the crown ether O atoms. The strongest Hj jO bonds in complexes of dibenzo-18-crown-6 ether with ammonium cation have a CE of 0.9 eV per bond [7] and bond distances of 1.8 A. The H atoms of the methylene and/or the phenyl group interact with the O atoms of ethers. The weakest interactions observed are between H atoms and phenyl groups as well as between two phenyl groups. In addition, the interactions are not always 1... 

The two atactic polymers just cited may be unusual for different reasons phenyl group interaction in the case of ar-PS (see Section VI) and hydrogen bonding plus chain stiffness for the poly(methacrylic acid) system. But gelation behavior is likely general to most, if not all, atactic polymers. 

The effect of an o>-phenyl group as a function of the alkyl chain length has been studied in 3-(through-space interaction has been evidenced on the reactivity of the thiocarbonyl group. 

In Rhodamine 6G, also sold as Rhodamine F5G [989-38-8] (15), the caiboxy estei gioup prevents fiee rotation of the lower phenyl group. Its position is roughly perpendicular to the plane of the other three rings. Retention of color strength is good because there is less electronic interaction between the lower ring and the rest of the molecule. 

From studies reported in the references in Table 5 (Section 4.04.1.3.1) the dihedral angle between a phenyl and a pyrazole ring in the crystalline state, falls between 4° and 22° when the phenyl group is in the 3- or 4-position. The planar conformation of C-formylpyrazoles (57) and the resonance interaction between them (87) has already been discussed in connection with H NMR (Section 4.04.1.3.3(i)) and IR studies (Section 4.04.1.3.7(iii)). 

Two hydrophobized polymers, MA-DP-A20 (phenyl group grafted in 20 mol%) and MA-DP-H68 (hexyl group grafted in 68 mol%), were selected for the evaluation of the interaction between polymers and cell membranes... 

Variable-temperature HNMR spectroscopic studies on l-phenyl-3/7-naphtho[l,2-c]azepine and the isomeric l-phenyl-37/-naphtho[2,l-c]azepine indicate that in the [l,2-c]-isomer severe steric interactions between the phenyl group and the adjacent naphthalene ring prevent ring inversion at room temperature.39... 

The consequences with respect to the corresponding thietane dioxides are straightforward in the trans-isomer, 187a, one phenyl group (i.e. R1) is necessarily axial, whereas in the isomer 187b both substituents are equatorial (equation 76). Clearly these preferred conformations minimize the potential repulsive interaction between 1,3-diaxial substituents66. 

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