Phencyclone Diels-Alder adducts as a new crystalline host. Role of CH···π and CH···O interactions
摘要:
A series of crystalline host compounds, which have a bicyclo[2.2.1]heptene-7-one system, has been synthesized and their inclusion behavior has been investigated. The cycloadduct of phencyclone and N-naphthylmaleimide forms a 1:1 crystalline inclusion complex with 2-butanone. The crystal structure indicates the presence of weak lattice forces supported by C-H ...pi and C-H ... O interactions. (C) 1998 Elsevier Science Ltd. All rights reserved.
The D/H isotope effect for the CH-pi interaction was studied experimentally and computationally. First, a series of molecular balances that are very sensitive to changes in the strength of the CH-pi interactions in solution were designed. Balances with deuterated and non-deuterated alkyl groups were synthesized, and their intramolecular CH-pi interactions were compared. The geometries of their intramolecular CH-pi and CD-pi interactions were characterized in the solid state by X-ray analysis, and the strength of each interaction was characterized in solution by the folded/unfolded ratio as measured by H-1 NMR spectra. Second, the relative strengths of the CH-pi and CD-pi interactions were also assessed computationally using dispersion-corrected DFT (PDE-D2/6-31+G*). No significant differencee was observed in either the experimental or theoretical studies, indicating that the D/H isotope effect for the CH-pi interaction is either very small or nonexistent.
A series of non-hydroxylic crystalline host compounds, [4 + 2]Ï cycloadducts of phencyclone and N-arylmaleimides having a bicyclo[2.2.1]heptene-7-one system, was synthesized and their inclusion behavior investigated. X-Ray crystal analyses of the inclusion compounds of the N-(1-naphthyl) derivative with butan-2-one, the N-(m-tolyl) derivative with p-xylene, together with the guest-free host and the N-(p-tolyl) derivative with m-xylene indicate that the âspaceâ surrounded by the phenanthrene ring, two phenyl rings and bridge carbonyl of the 1,3-diphenyl-1,3-dihydrocyclopenta[l]phenanthren-2-one moiety plays an important role, not only in the formation of inclusion complexes with the aromatic guests but also in hostâhost interactions. In every case, the N-aryl succinimide assists complex formation with the guests, in which the weak lattice forces due to CâHâ¯Ï
and CâHâ¯O interactions are operative. Methyl-substituted benzenes are effectively recognized by the CâHâ¯Ï interactions between the guest molecules and the phenanthrene ring of the hosts.
dissected halogen–aryl π interactions experimentally using a bicyclic N-arylimide based moleculartorsionbalances system, which is based on the influence of the non-bonded interaction on the equilibria between folded and unfolded states. Through comparison of balances modulated by higher halogens with fluorinebalances, we determined the magnitude of the halogen–aryl π interactions in our unimolecular
Experimental Study of the Cooperativity of CH−π Interactions
作者:Chen Zhao、Ping Li、Mark D. Smith、Perry J. Pellechia、Ken D. Shimizu
DOI:10.1021/ol5014729
日期:2014.7.3
A series of new torsional molecular balances was designed to study the cooperativity of CH-pi interaction in the solid state and in solution. The measured interaction energies correlated better to the number of participating alkyl carbons than to the number of CH-pi contacts. The methyl and ethyl groups displayed additive interaction energies. However, the branched isopropyl group displayed strong positive cooperativity with higher than predicted interaction energies.