Showing papers in "Annual reports on NMR spectroscopy in 1983"
TL;DR: In this paper, rotational correlation times in nuclear magnetic relaxation are investigated. But rotational motion of molecules in the gas phase is well represented by the equipartition of energy theorem and the laws of statistical mechanics, both of which are premised on the view that, except during instantaneous collisions, the molecules move independently of one another.
Abstract: Publisher Summary This chapter focuses on rotational correlation times in nuclear magnetic relaxation The rotational motion of molecules in the gas phase is well represented by the equipartition of energy theorem and the laws of statistical mechanics, both of which are premised on the view that, except during instantaneous collisions, the molecules move independently of one another Between collisions, the angular velocity is uniform and is determined solely by the molecule's moment of inertia and the temperature For most molecules in the liquid phase, the rotation rate depends upon the viscosity and is independent of the moment of inertia, indicating that intermolecular frictional forces rather than inertial factors are paramount During its brief lifespan, nuclear magnetic resonance (NMR) spectroscopy has quickly become the most powerful method for investigating the intimate details of this relationship
79 citations
TL;DR: In this paper, the authors present the Fluorine-19 NMR data presented in the literature between January 1979 and the end of June 1981, and the major part of this chapter consists of tables containing chemical shift and spin-spin coupling constant information for compounds in the liquid state or in solution.
Abstract: Publisher Summary This chapter presents the Fluorine-19 Nuclear Magnetic Resonance Spectroscopy data present in the literature between January 1979 and the end of June 1981. The major part of this chapter consists of tables containing chemical shift and spin-spin coupling constant information for compounds in the liquid state or in solution. The remaining part covers studies in solids and liquid crystals, together with biological applications and theoretical studies involving F-19 NMR. The tables are arranged according to the type of carbon (or element) to which the fluorine nucleus is bound. The appearance of a compound, with more than one type of fluorine-bonded carbon, in a particular table is according to which fluorine has its chemical shift reported and/or comes higher in the list of tables. Similarly where only coupling constant information is reported the same priority exists. Chemical shift information takes priority over coupling constant information. The only exception is where an attempt has been made to include all the data for carbonium ions and carbanions irrespective of whether fluorine is directly attached to the charged carbon or not. Most of the table consists of (a) the molecular formula of the compound, (b) the structure of the compound, (c) the F-19 chemical shift data, (d) the F-19 spin-spin coupling constant data, and (e) the literature reference number with the reference compound index, given in parentheses, where applicable. Each table is arranged according to the index of the molecular formulae, and the convention adopted for priority of the elements is C, F, H, and then the other elements in alphabetical order.
23 citations
TL;DR: In this paper, the authors describe characteristic features of the NMR spectra of alkaloids, illustrated by examples taken predominantly from papers published during the period January 1969-June 1972.
Abstract: Publisher Summary This chapter describes characteristic features of the nuclear magnetic resonance (NMR) spectra of alkaloids, illustrated by examples taken predominantly from papers published during the period January 1969–June 1972. In many of these papers, alkaloid structures have been assigned using NMR structure correlations established prior to the period under review and in some cases this work has been included. The classification of the alkaloids into groups follows that adopted in the Chemical Society specialist report on alkaloids. The classification occasionally differs from that in alkaloid texts on the basis of the volume of NMR data available, a relatively small alkaloid group may be allotted a full sub-section and an important family incorporated into a related group. In addition, if NMR spectral similarities between certain alkaloids are great enough then these alkaloids are discussed together even though this necessitates removal of the alkaloid from its “natural” section. S0066410308603282
17 citations