85337-90-2Relevant academic research and scientific papers
Circular Dichroism Studies on Three Isomeric Dimethylbenzo-15-crown-5 Ethers and Some of Their Complexes
Mack, Mark P.,Hendrixson, Richard R.,Palmer, Richard A.,Ghirardelli, Robert G.
, p. 2029 - 2035 (1983)
With ethyl lactate as an optically active precursor and with employment of Williamson reactions, three isomeric and axially symmetric dimethylbenzo-15-crown-5 ethers were prepared and characterized: (5R,15R)-5,15-dimethyl-5,6,8,9,11,12,14,15-octahydrobenzo-1,4,7,10,13-pentaoxacyclopentadecin and the (6S,14S)-6,14-dimethyl and (8S,12S)-8,12-dimethyl isomers, termed the α, β, and γ isomers, respectively.The circular dichroism spectra of the ethers and their complexes with Na+ in CH3OH have been determined and interpreted in terms of the gross overall orientationof the macrocycle in relation to the aromatic ring.The behavior of the γ-isomer with Ba2+ and with low ratios of K+ suggests dominance of 2:1 (sandwich) complexes.
Recognition by A New Chiral Dimethyl-substituted Phenanthrolino-18-Crown-6 Diester Ligand of the Enantiomers of Various Organic Ammonium Perchlorates
Wang, Tingmin,Bradshaw, Jerald S.,Huszthy, Peter,Kou, Xiaolan,Dalley, N. Kent,Izatt, Reed M.
, p. 1 - 10 (2007/10/02)
The new chiral dimethyl-substituted phenanthrolino-18-crown-6 diester ligands and (see Figure 1) were prepared through the reactions of 1,10-phenanthroline-2,9-dicarboxylyl dichloride with (S,S)-dimethyl-substituted triethylene glycol and (S,S)-dimethyl-substituted benzotriethylene glycol, respectively.The complexation of (S,S)-3 with the enantiomers of various organic ammonium perchlorates in various solvent systems was studied by 1H nmr spectral techniques and molecular mechanics.The degree of enantiomeric recognition was determined by the difference in the free energy of activation values (ΔΔGC) and the difference in log K values for these interactions.The extensive ? system in the ligand plays an important role for the strong interaction and recognition.The 1H nmr NOESY spectra and molecular mechanics calculations for the interactions of the new ligand with the organic ammonium salts further proved the existence of a ?-? interaction.
