Thyminoxetane als Ladungsfalle zum chemischen Nachweis des Nucleinsäure‐vermittelten Überschusselektronentransfers

Abstract

Die Wanderung von Elektronen nachweisen: Thyminoxetane ermöglichten es, dank ihres günstigen Redoxpotentials und der schnellen Cycloreversion den Transfer von Überschussladungen in Nucleinsäuren in außergewöhnlich hohen Quantenausbeuten zu verfolgen (siehe Schema; PNA=Peptidnucleinsäure). Untersucht wurde die Distanzabhängigkeit des Ladungstransfers, die typisch für einen Hopping‐Mechanismus ist.

Solid‐Phase Synthesis of Acid‐Sensitive N‐(2‐Aminoethyl)glycine‐PNA Oligomers by the Fmoc/Bhoc Strategy

“…A loss of about 20 % in yield was due to acid‐mediated hydrolysis of the oxetane moiety. The integrity of the oxetane moieties in oligomers 12 – 20 was confirmed by HR‐ESI‐MS (Table 2) and by subsequent excess electron transfer experiments, which are described elsewhere 4a…”

“…As part of our investigation of long‐distance excess electron transfer, (2‐aminoethyl)glycine‐PNA needed to be functionalized with both an electron donor and an acceptor group (Figure 1). 4a The PNA strand was used to address the PNA/DNA double or triple strands with the required modifications, since PNA/DNA complexes are known to be structural mimics for the corresponding oligonucleotide pairing complexes in the B‐DNA conformation 5. Our electron transfer studies required the synthesis of bis‐functionalized PNA oligomers containing a flavin moiety for “charge injection” and a highly acid‐sensitive thymine oxetane for “charge trapping”,4 and so a technique for the preparation of bis‐functionalized acid‐sensitive (2‐aminoethyl)glycine‐PNA oligomers based on the Fmoc/Bhoc solid‐phase peptide synthesis is presented, together with syntheses of the functionalized amino acid building blocks.…”