Fluorescent Oligonucleotides Containing a 2-Ethynylfluorene- or 2-Ethynylfluorenone-labeled 2′-Deoxyguanosine Unit: Fluorescence Changes upon Duplex Formation.

Two new DNA probes bearing a fluorescent deoxyguanosine unit labeled with 2-ethynylfluorene ( GFL) or 2-ethynylfluorenone ( GFO) were synthesized and examined for their efficiency as quencher-free linear beacon probes. Oligodeoxynucleotides ( ODNs) containing a GFL or GFO unit exhibit low thermal selectivity and few distinctive fluorescence changes upon duplex formation due to the syn conformation about the glycosidic bond. An exciplex emission was observed when the GFL unit of ODNs bearing adenine flanking bases was positioned opposite to the adenine nucleobases. [ABSTRACT FROM AUTHOR]