Modified 26 and 28 pi hexaphyrins with five meso-links: optical, redox, and structural properties.

The syntheses of new aromatic 26pi and non-aromatic 28pi hexaphyrins through a [4+2] acid catalyzed condensation of easily available and air-stable precursors are reported. Both 26pi and 28pi hexaphyrins are reversibly transformed into one another by two-electron reduction with NaBH(4) or two-electron oxidation with dichlorodicyanobenzoquinone (DDQ) respectively. Detailed optical and NMR spectral studies suggests that the [26]hexaphyrin is aromatic and possesses a diatropic ring current, while [28]hexaphyrin exhibits non-aromatic characteristics.

Partial characterization of Mycobacterium fortuitum and Mycobacterium smegmatis auxotrophs by syntrophism using Bacillus subtilis.

Syntrophism (cross-feeding) could be demonstrated between mutants of Mycobacterium fortuitum and Mycobacterium smegmatis, and previously characterized mutants of Bacillus subtilis, auxotrophic for arginine, histidine, lysine or phenylalanine. Based on this cross-feeding data, the possible site of blockage in the biosynthetic pathways of the mutants could be inferred.