An introduction to distance geometry applied to molecular geometry

摘要

The most common way of determining the structures of molecules in a solution is nuclear magnetic resonance (NMR). The signals measured are caused by the flipping of the spins of paramagnetic nuclei in a magnetic field. The strengths of the signals depend on the proximity of the nuclei to each other. The interactions are short range, within 0.5 nanometers (nm). NMR is used as a sensitive tool to investigate how close atoms are to each other, which in turn provides information about the angles, especially dihedral angles, whose twists can change the molecule from one conformation to another. The most commonly used paramagnetic isotope is the simple hydrogen-1 isotope that has two spin states—up and down. It is plentiful in the functional groups of biologically interesting molecules.