A series of pyridine and bipyridine molecules combining dual fluorescent (dansyl)
and magnetic (free radical) probes has been prepared by a linear multistep protocol
from the corresponding monodansylated derivatives. The grafting of the flexible aliphatic
radical is realized by the use of a chloromethylnitronyl nitroxide derivative under
basic conditions and with KI as a mediator. The synthetic potential of 2-[(5-dimethylamino-1-naphthalenesulfon-amide)methyl]-6-formylpyridine
is assessed by the construction, in a first step, of an aliphatic nitroxide radical
and subsequently of an additional aromatic radical. The synthetic methods reported
herein provide a practical approach to the rational design of ligands bearing various
kinds of functionalities such as chromogenic and spin-labeled fragments. A significant
merit of this method is that it allows the introduction of the fluorescent substituent
onto the pyridine or bipyridine framework at the beginning of the synthetic protocol.
pyridine - bipyridine - dansyl - nitroxide radicals - absorption spectrum