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The density functional theory is employed to determine the efficiency of 11 exchange-correlation (XC) functionals to compute the 1 H and 13 C NMR chemical shifts of p -tert-butylcalix[4]arene (ptcx4, R 1 = C(CH 3 ) 3 ) and congeners using the 6-31G(d,p) basis set. The statistical analysis shows that B3LYP, B3PW91 and PBE1PBE are the best XC functionals for the calculation of 1 H chemical shifts. Moreover, the best results for the 13 C chemical shifts are obtained using the LC-WPBE, M06-2X and w B97X-D functionals. The performance of these XC functionals is tested for three other calix[4]arenes: p -sulfonic acid calix[4]arene ( sfxcx4 - R 1 = SO 3 H), p -nitro-calix[4]arene ( ncx4 , R 1 = NO 2 ) and calix[4]arene ( cx4 - R 1 = H). For 1 H chemical shifts B3LYP, B3PW91 and PBE1PBE yield similar results, although B3PW91 shows more consistency in the calculated error for the different structures. For 13 C NMR chemical shifts, the XC functional that stood out as best is LC-WPBE. Indeed, the three functionals selected for each of 1 H and 13 C show good accuracy and can be used in future studies involving the prediction of 1 H and 13 C chemical shifts for this type of compounds.

A mixture of the E and Z isomers of ethyl 2-cyano-3-((4-fluorophenyl)amino) acrylate was synthesized and characterized by elemental analysis, attenuated total reflectance-Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy. The structure of the Z isomer was determined by single crystal X-ray diffraction, which revealed a three-dimensional supramolecular network governed by C H⋯N, C H⋯O, and C H⋯F hydrogen bonds and π⋯π stacking interactions. The combination of these interactions plays an important role in stabilizing the self-assembly process and the molecular conformation. Hirshfeld surface analysis indicated the roles of the noncovalent interactions in the crystal packing, which were quantified by fingerprint plots and DFT calculations.

The single crystal structure of seven tri- and tetracyclic ozonides derived from 8-oxabicycle[3.2.1]oct-6-en-3-ones have been characterized by X-ray diffraction method. Five ozonides ( 4 , 5 , 6 , 7 and 8 ) crystallize in the monoclinic crystal system with P2 1 /c space group. Compound 3 crystallize in the unusual centrosymmetric space group R 3 ¯ m, which represents ∼0.04% of the total number of structures know. The supramolecular structure of 3 forms infinite channels in a hexagram fashion, resulting in a honeycomb-like structure. Semi-empirical (PM6) and density functional theory methods (DFT) with the B3LYP functional and the 6-31G(d) basis set were used to optimize the geometries and compute structural parameters (bond lengths, angles and dihedral angles) that could be compared to the refined crystal structure. The theoretical results show good agreements with the experimental structure.

Experimental 1 H chemical shift analysis for the camphor-based chiral γ-amino alcohol 2 shows a difference of 0.9 ppm for the two diastereotopic hydrogens H 11a and H 11b . In contrast, for the exo adduct ( 1 ) and its acetate ( 3 ) these hydrogens have very similar chemical shifts. DFT calculations followed by NBO analysis show that these differences in chemical shifts arise as a consequence of an intramolecular hydrogen bond O H⋯N in 2 , which restricts its conformational mobility. In the most stable conformer of 2 , the interaction of the nitrogen lone-pair with the vicinal σ * (C H 11a ) antibonding orbital shifts that hydrogen downfield by 0.9 ppm. This is confirmed by experimental NMR studies based on NULL.

In this work we describe a systematic and comparative study of the 17 O NMR and related parameters of 17 polycyclic compounds: bicyclic, tricyclic, tetracyclic ( endo–endo and endo–exo fusion ), pentacyclic compounds (ketone; endo and exo -alcohols), hexacyclic alcohol. Concentration, temperature and solvent effects on the 17 O NMR chemical shifts and the relaxation rate are also described. We compare all experimental 17 O NMR chemical shifts with chemical shifts calculated from gauge-independent atomic orbitals within density functional theory (GIAO-DFT). Correlations between calculated and experimental 17 O NMR chemical shifts for respective functional groups were carried out and linear equations for chemical shift predictions were generated.