Optically active roof-shape amines were prepared and scanned as chiral solvating agents to study molecular recognition of acids by NMR analysis. Three types of amines were studied to establish a match-mismatch effect for structurally diverse acid analytes. Single-crystal X-ray diffraction analysis was performed on the diastereomeric salts of roof-shape amines and both isomers of mandelic acid to establish molecular conformation and correlate the absolute configuration with the observed NMR shift. The present system also recognizes the two isomers of weakly acidic BINOL and its derivatives.
Optically pure dicyano oxa[7]helicenes and helicene-like molecules have been prepared and investigated for their optical behavior. The isomers of the intermediate 4,4′-biphen-anthrene-3,3′-diol were resolved by physically separating their 1-menthyl carbonate derivatives. In this work a mild method was developed to cleave ArOMe in presence of a cyano group. The optical rotation of atropisomeric diol, helicenes-like compounds and the oxa[7]helicenes was observed to be in increasing order, while the molecules also showed good response to circularly polarized luminescence.
Optically active roof shape derivatives of benzyl amines were synthesized and screened as chiral solvating agents for the study of molecular recognition of chiral compounds by NMR and UV spectroscopy. The effect of substituents on the aromatic ring of benzyl unit is investigated to assess the binding ability with the analyte and an experimental correlation is observed. Altering the substituents on the ring of benzyl amine and the acidic substrates, significantly influence the CSA interactions. The supramolecular interactions between acid and amine in the single crystal X-ray analysis of the diastereomeric salts provide further insight of the mode of molecular recognition.
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