Method for the synthesis of nucleotide derivatives wherein molecules of interest are grafted on the oligonucleotide with the help of a "click chemistry" reaction between an azide function on the molecule of interest and an alkyne function on the oligonucleotide, or between an alkyne function on the molecule of interest and an azide function on the oligonucleotide. Intermediate molecules, notably alkyne functionalized oligonucleotides, grafted oligonucleotides, azide functionalized oligonucleotides, oligonucleotide micro arrays containing them and the use of those grafted oligonucleotides for biological investigation and for cell targeting.