RESUMO
MSpin-JCoupling is a modular program for the prediction of scalar couplings using a large variety of Karplus relationships. The program was specially designed for small molecule analysis and can be run in graphical or command-line mode. The architecture of the program is highly modular, and new equations can be rapidly implemented, through a complete C++ programming interface, and deployed as run-time loadable plugins.
RESUMO
A new DMSO-compatible aligning gel based on cross-linked poly(2-hydroxylethyl methacrylate) (poly-HEMA) has been developed. Due to a significant difference in bulk magnetic susceptibility between the DMSO inside and outside the gel, it is possible to simultaneously collect isotropic and anisotropic NMR data, such as residual dipolar couplings (RDC), in the same NMR tube. RDC-assisted structural analysis of menthol and the alkaloid retrorsine is reported as proof of concept.
RESUMO
The use of the cetylpyridinium chloride (CPCL)/NaCl/hexanol liquid crystal allowed the measurement of (1)D(CH) residual dipolar couplings of the isoquinoline alkaloid salsolidine in its protonated state. Populations of its two half-chair forms were determined by using the single alignment tensor approximation combined with global superposition of conformers. These populations were in good agreement with the DFT-computed energies for both conformers.
RESUMO
A procedure for the direct use of (1)D(CH) residual dipolar couplings (RDCs) from freely rotating groups in the structural analysis of small molecules was implemented. (1)D(CH) RDCs were used to determine both the preferred conformation and the stereochemical assignment of the diastereotopic geminal methyls of 8-phenylmenthol. Furthermore, a method was also set up to fit RDC data to a set of conformations in solution on the assumption that they all have the same alignment tensor.
