56930-39-3Relevant articles and documents
Molecular motion in crown ethers. Application of 13C and 2H NMR to the study of 4-carboxybenzo-24-crown-8 ether and its KNCS complex in solution and in the solid phase
Buchanan,Moghimi,Ratcliffe
, p. 1437 - 1446 (1996)
Large-amplitude solid phase molecular motion has been detected in the macrocyclic ring of the title crown either via 13C CPMAS NMR. To study the details of the dynamic processes, two selectively deuterated d4 derivatives have been prepared and examined via 2H NMR as a function of temperature. A phase change occurring around 277 K has been verified by differential scanning calorimetry (DSC) and a model for the motional processes has been developed involving equivalent two-site flips of the CD2 groups. The amplitude of the CD2 motions apparently decreases the closer the group is to the aromatic ring. The influence of KNCS complexation on the 13C CPMAS spectrum and on 13C spin lattice relaxation times in solution has been explored.
Conductance study of alkali metal complexes with 4′-carboxy-benzo-24-crown-8 and 4′-amido-benzo-24-crown-8 in nitromethane, acetonitrile and dimethylformamide solutions
Ganjali,Rouhollahi,Moghimi,Shamsipur
, p. 1172 - 1181 (2007/10/03)
Synthetic procedures have been developed for the preparation of two new crown ethers 4′-carboxy-benzo-24-crown-8 (COOH-B24C8) and 4′-amido-benzo-24-crown-8 (CONH2-B24C8). The formation of alkali metal complexes with the two crown ethers was investigated in nitromethane, acetonitrile and dimethylformamide solutions conductometrically at 25.0°C. Stability constants of the resulting 1:1 complexes were determined by the molar conductance-mole ratio data. In all cases, CONH2-B24C8 was found to form a more stable alkali complex than does COOH-B24C8. For both crown ethers, and in all three solvents used, the stability of the resulting alkali complexes was found to vary in the sequence K+ > Rb+ > Cs+ > Na+ > Li+. The stabilities of the complexes varied inversely with the Gutmann donicity of the solvents.