Proton transfer reactions

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A TD-DFT/DFT study on the ESIPT and photophysical properties of symmetrical 2-hydroxybenzilidene1,3-diamines derivatives

The geometries and relative stabilities of 15 tautomeric forms and the corresponding isomers of the studied molecules have been identified and their relative stabilities are investigated. The potential energy profiles and intrinsic reaction coordinates (IRC) calculations along the proton transfer coordinates both in the ground and in the excited state are monitored as well. The impact of the donating (OMe) and withdrawing (NO2) groups on the single and double proton transfers are investigated both in the gas phase and solution.

9p dianmotminh02 03-05-2024 10 2 Download

Báo cáo khoa học: Proton transfer in the oxidative half-reaction of pentaerythritol tetranitrate reductase Structure of the reduced enzyme-progesterone complex and the roles of residues Tyr186, His181 and His184

The roles of His181, His184 and Tyr186 in PETN reductase have been examined by mutagenesis, spectroscopic and stopped-flow kinetics, and by determination of crystallographic structures for the Y186F PETN reductase and reduced wild-type enzyme—progesterone complex. Residues His181 and His184 are important in the binding of coenzyme, steroids, nitro-aromatic ligands and the substrate 2-cyclohexen-1-one.

12p fptmusic 12-04-2013 40 3 Download

Additional Aspects of Aqueous Equilibria

The solubility of a partially soluble salt is decreased when a common ion is added. Consider the equilibrium established when acetic acid, HC2H3O2, is added to water. At equilibrium H+ and C2H3O2- are constantly moving into and out of solution, but the concentrations of ions is constant and equal. If a common ion is added, e.g. C2H3O2- from NaC2H3O2 (which is a strong electrolyte) then [C2H3O2-] increases and the system is no longer at equilibrium. So, [H+] must decrease.

45p tranvtue 02-11-2012 58 3 Download
Acid-Base Equilibria

Acid: vị chua, làm thuốc nhuộm đổi màu Bases: vị đắng, cảm giác nhớt. Arrhenius: acids làm tăng [H+], bases làm tăng [OH-] trong dung dịch. Arrhenius: acid + base  salt + water. Problem: định nghĩa này chỉ áp dụng được trong dung dịch nước The H+ Ion in Water The H+(aq) ion is simply a proton with no electrons. (H has one proton, one electron, and no neutrons.) In water, the H+(aq) form clusters. The simplest cluster is H3O+(aq). Larger clusters are H5O2+ and H9O4+. Generally we use H+(aq) and H3O+(aq) interchangeably....

45p tranvtue 02-11-2012 57 3 Download