Synthesis and characterisation of novel 3′-O- and 5′-O- modified azobenzene-thymidine phosphoramidites and their oligonucleotide conjugates as colorimeter DNA probes and FRET quenchers

The synthesis of two new ‘first generation’ azobenzene based thymidine phosphoramidites 1 and 2 having the chromophore (DABCYL) covalently incorporated as an ester in the 3′-O- and 5′-O-positions of the deoxyribose, and the incorporation of these molecules into 16-mer Chronic Myeloid Leukaemia (CML) antisense oligonucleotides, giving 7 and 8, respectively, is described. These compounds were designed as highly coloured probes, and to participate in a Fluorescence Resonance Energy Transfer (FRET) mechanism in the design of novel molecular beacons.