Oligothiophene phosphoramidites for oligonucleotide labelling

We report the synthesis and characterization of two oligonucleotides (a tetramer and a 19-mer) labelled with a fluorescent oligothiophene and obtained by means of the phosphoramidite of the fluorophore. The conjugate compounds were synthesized in solid phase and characterized by means of mass spectrometry, multinuclear NMR, UV–vis and photoluminescence spectroscopies. The results show that this approach is suitable as a general route for the preparation of oligonucleotides labelled with oligothiophene-based fluorophores.