Spin Label Investigation of the Crown Eher. Complex Formation between the Veratrole Analogue of Phenoxyl-labeled Benzo-15-crown-5 and Alkali and Alkaline Earth Metal Salts in Frozen Solution

Article abstract of DOI:10.1246/bcsj.58.322

A stable "phenoxyl-veratrole" (2), a veratrole analogue of "phenoxyl-benzo-15-crown-5" (1), was prepared and the complex formation between 2 and the alkali and alkaline earth metal salts has been studied by the ESR technique.Existence of the 2:1 complex of 2 with K+,Rb+ and Cs+ salts was confirmed by the observation of the triplet ESR spectra in ethanol rigid matrix at 77 K.Essentially the same g- and D-tensor values were observed for all the 2:1 complexes, indicating similar conformation of the ligand molecule 2.By comparing the observed D and E parameters with those of the 2:1 complexes reported for the alkali and alkaline earth metal complexes of 1 in a previous paper (Ref.10), the structure of the 2:1 complex in ethanol rigid matrix was discussed.On the other hand the results of the ESR measurements of the Li+,Na+, and alkaline earth metal complexes suggested a 1:1 complex formation between 2 and the metal salts.