Large transition state stabilization from a weak hydrogen bond
作者:Erik C. Vik、Ping Li、Josef M. Maier、Daniel O. Madukwe、Vitaly A. Rassolov、Perry J. Pellechia、Eric Masson、Ken D. Shimizu
DOI:10.1039/d0sc02806a
日期:——
A series of molecular rotors was designed to study and measure the rate accelerating effects of an intramolecular hydrogen bond. The rotors form a weak neutral O–H⋯OC hydrogen bond in the planar transition state (TS) of the bond rotation process. The rotationalbarrier of the hydrogen bonding rotors was dramatically lower (9.9 kcal mol−1) than control rotors which could not form hydrogen bonds. The
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
Transition-State Stabilization by n→π* Interactions Measured Using Molecular Rotors
作者:Erik C. Vik、Ping Li、Perry J. Pellechia、Ken D. Shimizu
DOI:10.1021/jacs.9b08542
日期:2019.10.23
A series of 16 molecular rotors were synthesized to investigate the ability of n→π* interactions to stabilize transition states (TS) of bond rotation. Steric contributions to the rotational barrier were isolated using control rotors, which could not form n→π* interactions. Rotors with strong acceptor π* orbitals such as ketones, aldehydes, and nitriles had greatly increased rates of rotation. The TS
作者:Ping Li、Erik C. Vik、Josef M. Maier、Ishwor Karki、Sharon M. S. Strickland、Jessica M. Umana、Mark D. Smith、Perry J. Pellechia、Ken D. Shimizu
DOI:10.1021/jacs.9b06363
日期:2019.8.14
carbonyl-aromatic (CO-π) interactions. Carbonyl oxygens were observed to form repulsive interactions with unsubstituted arenes and attractive interactions with electron-deficient arenes with multiple electron-withdrawing groups. The repulsive and attractive CO-π aromaticinteractions were well-correlated to electrostatic parameters, which allowed accurate predictions of the interaction energies based on the
Srivastav, Kamal K.; Srivastava, Vandana; Verma, Shiva M., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1999, vol. 38, # 6, p. 672 - 678
作者:Srivastav, Kamal K.、Srivastava, Vandana、Verma, Shiva M.、Bharadwaja