Dye Polymers Constructed from Chelating Pyridine Ligands

Dye Polymers Constructed from Chelating Pyridine Ligands 

2 -terpyridine (tpy) Hgand is ideally suited for the formation of coordination polymers due to its favorable structural properties. In contrast to the 2,2 -bipyridine ligand, octahedral tpy complexes can not form A and A isomers, and as the 4 -position can be easily functionahzed it allows the alignment of two residues in an exact 180° angle [82]. 

A red fluorescent coordination polymer (32) was obtained by our research group from a tpy-functionalized perylene bisimide chromophore by complexation with zinc triflate [85]. The polymer 32, which is readily soluble in chloroform/methanol mixtures and DMF, retains the excellent fluorescence properties of the free ligand and shows reversible binding, thus, the chain length decreases upon addition of an excess amount of Zn . The polymeric structure was estabhshed by NMR using a dimer model compound as reference as well as by DOSY NMR, UV/vis spectroscopy, fluorescence anisotropy measurements, and AFM [86]. Further superstructures were ob- 

This concept was extended by Che et al. for a series of terpyridine containing chromophores [88]. The respective zinc coordination polymers obtained thereby were investigated by optical spectroscopy, NMR and viscosimetry. These coordination polymers exhibit fluorescence ranging from violet to yellow and two such polymeric compoxmds coifld be successfully incorporated into an electroluminescent device. Whereas in polymer 33 the green fluorescence originates from the fluorene unit located between the tpy ligands, the blue fluorescence in polymer 34 stems from the 4 -phenyl-substituted tpy ligand itself, so that in the latter case tpy acts as both the structural and the functional unit. 

In a similar approach two tpy units attached to an oHgo(phenylene viny-lene) unit could be polymerized with Fe by Meijer and coworkers [30]. Formation of polymer 35 could easily be characterized by UV/vis titration 

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