The stability of the PNA (peptide nucleic acid) thymine monomer ¿N-[2-(thymin-1-ylacetyl)]-N-(2-aminoaminoethyl)glycine¿ and those of various PNA oligomers (5-8-mers) have been measured at room temperature (20 degrees C) as a function of pH. The thymine monomer undergoes N-acyl transfer rearrangement with a half-life of 34 days at pH 11 as analyzed by 1H NMR; and two reactions, the N-acyl transfer and a sequential degradation, are found by HPLC analysis to occur at measurable rates for the oligomers at pH 9 or above. Dependent on the amino-terminal sequence, half-lives of 350 h to 163 days were found at pH 9. At pH 12 the half-lives ranged from 1.5 h to 21 days. The results are discussed in terms of PNA as a gene therapeutic drug as well as a possible prebiotic genetic material.
Abstract On irradiation of solutions of anthryl‐substituted cobalt(III) cage complexes, [(l‐(anthryl‐9‐methylamino)‐8‐methyl‐3,6,10,13,16,19‐hexaazabicyclo [6.6.6] eicosane) cobalt(III)]3+ or [(l‐(4‐an‐thryl‐9)‐3‐aza‐butyl‐l‐amino)‐8‐methyl‐3,6,10,13,16,19‐hexaazabicyclo [6.6.6] eicosane)cobalt (III)]3* in the presence of ethylenediaminetetraacetic acid and platinum catalysts hydrogen was produced. These complexes act as coupled photosensitizers (anthracene moiety) and electron relays (cobalt cage) to produce H2via energy trapping and intramolecular electron transfer initially. The intensity of fluorescence and the photochemical reactivity favour the latter complex and the excited singlet state of the anthracene chromophore is invoked as the intermediate state leading to the reduction of Co(III) to Co(II).
