The population imbalance between nuclear singlet states and triplet of strongly coupled spin-1/2 pairs, also known as order, is well protected against several common relaxation mechanisms. We study the 13C pairs in aqueous solutions 1,2-13C2 squarate over a range pH values. order accessed by introducing 18O nuclei to break chemical equivalence. dianion equilibrium with hydrogen-squarate (SqH?) ...

Chemical exchange phenomena in NMR spectra can be quantitatively interpreted to measure the rates of ligand binding, as well as conformational and chemical rearrangements. In macromolecules, processes that occur slowly on the chemical shift time scale are frequently studied using 2D heteronuclear ZZ or N(z)-exchange spectroscopy. However, to successfully apply this method, peaks arising from ea...

the ir and nmr spectra were coupled with quantum chemical calculations in dft approach usingthe hybrid b3lyp exchange-correlation functional to confirm the structure of 2-methoxycarbonyl-7-methyl-1,3-thiazino[3,2-b][1,2,4]triazine-4,8-dione 2d.

The static magnetic field dependence of chemical exchange linebroadening in NMR spectroscopy is investigated theoretically and experimentally. Two-site exchange (A / B) is considered with site A more highly populated than site B (pa > pb), a shift difference between sites equal to ∆ω, and an exchange rate constant given by kex. The exchange contribution to the transverse relaxation rate constan...

Ceria is an interesting material for high temperature redox applications like solar-thermal splitting of CO2 and H2O. Technical implementation and reactor design for solar-thermal redox-based fuel generation requires reliable data for the chemical surface exchange coefficient and the chemical diffusivity of oxygen. The results of thermogravimetric relaxation experiments and equilibrium oxygen i...

The nuclear magnetic resonance (NMR) spin relaxation rate constant in the rotating frame of reference R1 provides information on microsecond to millisecond ( s-ms) timescale kinetic processes that stochastically modulate the resonance frequencies of nuclear spins in molecules. Expressions for R1 are presented for two-site chemical exchange using both the conventional perturbation approach for e...

A salt metathesis reaction is a chemical process involving the exchange of bonds between two reacting chemical species, which results in the creation of products with similar or identical bonding affiliations. Hyperstructure theory is studied from the theoretical point of view and for its applications. In this paper, we provide some examples of hyperstructures associated with salt m...

Two-dimensional exchange spectroscopy (1-4) has become a very popular tool for the study of dynamic processes in liquids. Originally, chemical exchange (1,5) and cross-relaxation (6,7) were considered to be separate processes. Interference between the two processes (chemical exchange and cross-relaxation) was recognized early (7), but active treatment of the problem (8) was possible only follow...