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The case of 13C-labeledchloroform exchanging betweena free site in solution and the encaged site within the cryptophane-Dcavity is investigated using the measurements of longitudinal cross-correlatedrelaxation rates, involving the interference of the dipole–dipoleand chemical shielding anisotropy interactions. A compact theoreticalexpression is provided, along with an experimental protocol, basedon INEPT (insensitive nuclei enhanced by polarization)-enhanced double-quantum-filteredinversion recovery measurements. The analysis of the build-up curvesresults in a set of cross-correlated relaxation rates for both the 13C and 1H spins at the two sites. It is demonstratedthat the results can be given a consistent interpretation in termsof molecular-level properties, such as rotational correlation times,the Lipari–Szabo order parameter, and interaction strengthconstants. The analysis yields the bound-site carbon-13 chemical shieldinganisotropy, ΔσC= −58 ± 8 ppm,in good agreement with most recent liquid-crystal measurements andthe corresponding proton shielding anisotropy, ΔσH= 14 ± 2 ppm. [ABSTRACT FROM AUTHOR]

Enantiopure cryptophane derivatives 1and 2, possessing linkers of different nature(ethylenedioxy and propylenedioxy)connecting the two cyclotribenzylenes (CTB) units, were separatedby HPLC using chiral stationary phases. X-ray crystallographic structuresof the four enantiomers (+)-1, (−)-1, (+)-2, and (−)-2have been obtained,allowing the unambiguous determination of their absolute configuration(AC) in the solid state. The chiroptical properties of compounds 1and 2were determined from polarimetry, electroniccircular dichroism (ECD), vibrational circular dichroism (VCD), andRaman optical activity (ROA) experiments and were compared to thoseof cryptophane-A (3) derivative. VCD, ROA and ECD spectraof 1and 2were calculated by density functionaltheory (DFT) and time-dependent density functional theory (TDDFT)calculations, respectively, to confirm the AC of the cryptophane derivativesin solution. The (+)-PPand (−)-MMconfigurations were established for compounds 1and 2in chloroform solution, as already reported for the twoenantiomers of 3. This result is in agreement with theX-ray structures of the two enantiomers of 1and 2. [ABSTRACT FROM AUTHOR]