Triphenylamine derivatives useful as fluorophores in biology, in particular for two-photon microscopy; andcompositions comprising these derivatives, to the use of these compositions and of the derivatives themselves for labelling biological molecules (or “biomolecules”) such as nucleic acids, oligonucleotides, proteins, polypeptides, plasmids, and the like, for their examination in particular by two-photon microscopy, and to biomolecules labelled with the said derivatives.