1H-, 13C-, and 15N-NMR and ESI-TOF+ MS studies of a supramolecular complex of silver(I) and a cholaphane

Multinuclear magnetic resonance, electrospray ionization time‐of‐flight mass spectral and molecular modelling characterization of lithocholic acid amide esters with various nitrogen heterocycles

“…This indicates that the conformational preferences of the tail are changed when the cyclic structure is formed, as also happened in the cases of terephthalic-and thiophene-2,5-dicarboxylates of lithocholic acid piperazine diamides. 23,25 Furthermore, the cyclization caused broadening of some of the 13 C NMR signals of the bile acid moieties in 5, implying that the At 303 K, the 1 H NMR resonances of piperazine in 5 appeared unsymmetrical, resembling the piperazine pattern of 4 at lower temperatures (223 K; see Fig. 1).…”

“…This was believed to be due to the reduced flexibility and slower dynamics of the cholaphane ring observed also in the 13 C NMR chemical shifts as described above and found before also for thiophene-2,5-dicarboxylate and pyridine-2,6-and -3,5-dicarboxylate-closed cholaphanes. 24,25 Therefore, VT 1 H NMR runs at 223, 233 and 243 K were also performed for 5. As the temperature was lowered, the fine structure of the pattern became more apparent, indicating a slow exchange regime.…”

“…This also explains why the metal cations tend to complex outside the cavity, as observed in this work and by us before. 25 In order to obtain a guest molecule inside the molecular cavity, more rigid linkers than piperazine are needed. Alternatively, the synthesis could be performed in the presence of a guest acting as a template.…”

“…21 We have previously reported syntheses and spectral characterizations of several bile acid-based open dimers and cholaphanes. 22 -28 We have also investigated their alkali metal 24 and Ag(I) cation 23,25,27 binding properties. Recently, Dukh et al 29 reported studies on novel deep cavity calix [4]pyrroles derived from steroidal ketones (prepared from cholic acid), which have enantiomeric recognition potency towards some carboxylate anions.…”

Synthesis of Nitrogen‐ and Oxygen‐Containing Macrocycles—Derivatives of Lithocholic Acid

“…[14,15] Introduction of various functional groups makes them ideal compounds for molecular recognition. [16] The first synthetic cholaphanes were constructed by using the formation of cyclic amides as a key step. [15,17,18] To improve the flexibility of the macrocycle, ester groups were used for the cyclization.…”