Transformation of homonuclear two-dimensional NMR techniques into one-dimensional techniques using Gaussian pulses

Abstract

A general procedure is proposed, which allows the transtormation of most of the homonuclear two-dimensional NMR techniques into one-dimensional sequences by using semiselective Gaussian pulses. These techniques are particularly advantageous in cases where a limited amount of information is required for solving a chemical problem, e.g., a few connectivities, coupling constants, or NOE values. Applications of 1D COSY, 1D NOESY, 1D homonuclear relayed techniques, and 1D TOCSY are demonstrated. Furthermore, a variant of the ID COSY, the refocused ID COSY with z filter is suggested, which in combination with 1 D COSY allows the application of DISCO for the determination of coupling constants from multiplets in crowded regions. The 1 D NOESY sequence allows the measurement of NOES for very short mixing times and thus provides reliable values for buildup rates of transient NOEs. Selective excitation of a certain resonance may be impossible by conventional techniques, because it lies in a crowded region. In such cases by exploiting the J dependence of transfer functions (directed magnetization transfer) magnetization can be transferred selectively from a coupled nucleus to the one of interest. Its NMR parameters (J coupling, NOE) are then accessible via relayed COSY or relayed NOESY.