NMR spectroscopic detection of chirality and enantiopurity in referenced systems without formation of diastereomers

Enantiomeric excess of chiral compounds is a key parameter that determines their activity or therapeutic action. The current paradigm for rapid measurement of enantiomeric excess using NMR is based on the formation of diastereomeric complexes between the chiral analyte and a chiral resolving agent, leading to (at least) two species with no symmetry relationship. Here we report an effective method of enantiomeric excess determination using a symmetrical achiral molecule as the resolving agent, which is based on the complexation with analyte (in the fast exchange regime) without the formation of diastereomers. The use of N,N′-disubstituted oxoporphyrinogen as the resolving agent makes this novel method extremely versatile, and appropriate for various chiral analytes including carboxylic acids, esters, alcohols and protected amino acids using the same achiral molecule. The model of sensing mechanism exhibits a fundamental linear response between enantiomeric excess and the observed magnitude of induced chemical shift non-equivalence in the 1H NMR spectra

Apelin, Omentin-1, and Vaspin in patients with essential hypertension: association of adipokines with trace elements, inflammatory cytokines, and oxidative damage markers

PMID = 3258331

A cyclic porphyrin trimer as a receptor for fullerenes.

A cyclic porphyrin trimer has been synthesized which has a high affinity for fullerenes. It forms 1:1 complexes with C(60) and C(70) with association constants of 2 x 10(6) and 2 x 10(8) M(-1), respectively, in toluene. Its affinities for C(86) and La@C(82) are too strong to measure by fluorescence titration. The solvent dependence of the association constants shows that solvation of both the guest and the host influence the binding strength