Silver(I) Cation Complexation with 3α,3'α-Bis(pyridine-n-carboxy) Lithocholic Acid 1,2-Ethanediol Diesters (n = 2–4): 1H, 13C and 15N NMR Spectral Studies and Molecular Orbital Calculations
ABSTRACT Three isomeric molecular clefts: 3,3'-bis(pyridine-n-carboxy) lithocholic acid 1,2-ethanediol diesters (n = 2–4) 1–3 have been synthesized and their structures ascertained by 1H, 13C NMR and MALDI TOF MS. Their complex formation with Ag+-cation (added as AgO3 SCF3) have been investigated by means of NMR and molecular orbital calculations. The coordination behaviour of the silver(I) cation is dependent on the isomerism of the pyridine-n-carboxy moiety. In 1 (pyridine-2-carboxylato = picolinato) both NMR and theoretical calculations strongly suggest that the coordination occurs with the lone electron pairs of the pyridine nitrogen and carbonyl oxygen in both of the arms of the molecular cleft separately. In 2 and 3 (pyridine-3-carboxylato = nicotinato and pyridine-4-carboxylato = isonicotinato) where the distance between the pyridine nitrogen and carbonyl oxygen is too large to allow the same type of coordination as in 1, 3-complexation with the pyridine ring and carbonyl oxygen of the different arms of the molecular cleft simultaneously is suggested by molecular orbital calculations and supported also by NMR. No Ag+-cation coordination was observed with the 1,2-ethanediol oxygens in 1–3.
- SourceAvailable from: Radek Marek[Show abstract] [Hide abstract]
ABSTRACT: The implementation of both the directly and the inversely detected 15N NMR techniques at the natural abundance level of the 15N isotope is demonstrated for a diverse array of structural problems in organic chemistry. Following the application of 15N NMR to the elucidation of the structures of natural compounds and synthetic products, the 15N-detected electron distribution in such molecules and following their reactions with other molecules and ions is discussed. A significant part of the 15N structural analysis is devoted to the description of tautomers, rotamers, conformers, configurational isomers, and regioisomers. The changes in the 15N parameters induced in structurally related compounds are described briefly.At present, the optimum probe-tube-sample configuration makes it possible to acquire inverse-detected 1H-15N correlation spectra on samples, where the total available sample is limited to amounts of < 1 mg (for molecules <1000 Da and magnetic fields > 400 MHz). 15N NMR spectroscopy at the natural abundance level of 15N nuclei has become a powerful tool which has substantially extended the analytical arsenal of organic chemists.Current Organic Chemistry 01/2002; 6(1):35-66. · 2.54 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A review of the use of bile acid-based compounds as building blocks for designing novel supramolecular hosts for molecular recognition is presented. Pharmacological applications and the newest spectroscopic and computational studies of bile acid derivatives are also shortly considered.ChemInform 01/2001; 6(1).
- [Show abstract] [Hide abstract]
ABSTRACT: Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by1H, 13C and 15N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd2+-complexes (1+Cd and 2+Cd) in CD3OD solution have been detected by 1H,13C, 15N and 113Cd NMR. The 13C NMR chemical shift assignments of 1 and 2 and their Cd2+-complexes are based on DEPT-135 and z-GS 1H,13C HMQC experiments as well as comparison with the assignments of the related structures. The 15N NMR chemical shiftassignments of the ligands and theirCd2+-complexes are based on z-GS1H,15N HMBC experiments. 13C NMR chemical shift differences between 1and its 1:1 Cd2+-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd2+-complexation.Journal of inclusion phenomena and macrocyclic chemistry 01/2000; 37(1):121-130. · 1.17 Impact Factor