DCDHFs are brighter
in rigid (left: liquid
vs. frozen) or more viscous (right: QY vs.
viscosity) environments. When the dicyano bond on the furan has a lower barrier to rotate, the fluorophore is able to
nonradiatively relax via a twisted intramolecular
charge transfer (TICT) state. This effect can help lower background from unbound copies in solution.
Willets,
Callis, Moerner. J. Phys. Chem. B 2004, 108, 10465–10473.
DCDHF Environment Sensitivity