Pendant fluorophores, complexes

If the fluorophore is part of a large flexible molecule, e.g., it is a co-monomer incorporated in a flexible polymer chain or a pendant group covalently attached to a polymer chain or to a large polymeric nanoparticle, its reorientation relaxation is a complex process, which includes (1) fairly slow rotation of the whole nano-object, (2) reorientation motion of the probe with respect to some specific parts of the chain or of the nanoparticle (e.g., with respect to nano-structured domains differing in flexibility or in other important properties), and (3) fairly fast motion of the polymer structural units and rotation of the fluorophore around one or more single bonds, if it is attached to the chain or to the nano-object by a linker. From the practical point of view, it is convenient to classify the molecules according to the ratio of the fast correlation time to the longest time, which describes the motion of the whole particle. 

---