Some aspects of high‐pressure NMR

Abstract

Recent advances in the field of high-resolution NMR spectroscopy in both pure liquids and solutions, under high pressure, are reviewed. Experimental techniques employed for making the NMR measurements at high pressures are discussed. An overview of high-pressure NMR studies as applied to intramolecular dynamics, structures of liquids, molecular conformations and intermolecular interactions is presented.

High pressure in organic chemistry on the way to miniaturization

“…High pressure NMR techniques 59 have been reviewed by Jonas, 60 Merbach, 61 and Moore 62 and, recently, by Ando and Webb, 63 as well as by Damoense et al 64 for inorganic chemistry, and by Yonken and Linehan 65 for supercritical fluids. Such NMR probes must be nonmagnetic and of high mechanical strength: titanium and Be-Cu alloys, glass or quartz capillaries and sapphire give excellent results.…”

“…An electrochemical microreactor coupled to a continuous chromatographic separation process has been fabricated with a pressure resistance over 30 bar at flow rates of 10 ml min À1 . The electrochemical synthesis of 4-methoxybenzaldehyde (63), starting from 4-methoxytoluene (61) and proceeding via acetal (62), was chosen as a model reaction. The conversion and selectivity depend on the cell voltage (Scheme 17).…”

High-Pressure Raman Noncoincidence Effect and Conformation of Alkyl Side Chain in Alkyl Benzoates

“…High-pressure Raman experiments have been performed in our laboratory on many systems, examining effects such as collision-induced scattering, , vibrational dephasing, , reorientational correlation, , and noncoincidence. ,,,,, These experiments showed the importance of pressure as an experimental variable for the separation of the effects of internal energy and density and for modifying the intermolecular potential and relaxation processes. One of the important molecular level changes in liquids induced by external pressure is conformational changes in the molecules. , In fact, pressure is effective in perturbing the distribution of the conformers of hydrocarbon chain molecules. , Under the condition of high pressure, the conformational preferences are determined principally by the relative volume of the conformers, which is likely to be sensitive to the conformational changes due to folding of alkyl chain. Despite the relevance to understanding many important questions in functional fluids, polymers, and biomembrane lipids, , the pressure-induced conformational changes of hydrocarbon chains ,,, have not been extensively studied.…”

“…One of the important molecular level changes in liquids induced by external pressure is conformational changes in the molecules. 36,37 In fact, pressure is effective in perturbing the distribution of the conformers of hydrocarbon chain molecules. 38,39 Under the condition of high pressure, the conformational preferences are determined principally by the relative volume of the conformers, which is likely to be sensitive to the conformational changes due to folding of alkyl chain.…”