Molecular Rods Based on Oligo-spiro-thioketals.

We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers.

rac-1-[(2-Methoxyethyl)sulfanyl]-2-[(2-methoxyethyl)sulfinyl]benzene and its PdCl2 complex.

As an extension of recent findings on the recovery of palladium with dithioether extractants, single crystals of the chelating vicinal thioether sulfoxide ligand rac-1-[(2-methoxyethyl)sulfanyl]-2-[(2-methoxyethyl)sulfinyl]benzene, C(12)H(18)O(3)S(2), (I), and its square-planar dichloridopalladium complex, rac-dichlorido{1-[(2-methoxyethyl)sulfanyl]-2-[(2-methoxyethyl)sulfinyl]benzene-κ(2)S,S'}palladium(II), [PdCl(2)(C(12)H(18)O(3)S(2))], (II), have been synthesized and their structures analysed. The molecular structure of (II) is the first ever characterized involving a dihalogenide-Pd(II) complex in which the palladium is bonded to both a thioether and a sulfoxide functional group. The structural and stereochemical characteristics of the ligand are compared with those of the analogous dithioether compound [Traeger et al. (2012). Eur. J. Inorg. Chem. pp. 2341-2352]. The sulfinyl O atom suppresses the electron-pushing and mesomeric effect of the S-C-C-S unit in ligand (I), resulting in bond lengths significantly different than in the dithioether reference compound. In contrast, in complex (II), those bond lengths are nearly the same as in the analogous dithioether complex. As observed previously, there is an interaction between the central Pd(II) atom and the O atom that is situated above the plane.

A spectrophotometric assay for measuring the uptake of actinobolin by components of human enamel.

A spectrophotometric assay was developed for measuring the uptake of the antibiotic actinobolin by hydroxylapatite (HAP) or powdered human enamel. The assay is sufficiently sensitive to detect less than 2.0 mug actinobolin/ml of: 0.01 M sodium phosphate buffer at pH 5.5, 7.0, or 8.0; deionized water; deionized water containing 1% salivary supernatant; or each of the above indicated solvent systems containing 1-5 parts per million sodium fluoride. The utility of the assay system has been demonstrated by date which show that approximately 5-7 mug of actinobolin are bound per 10 mg of HAP or powdered enamel.