2,2 :6 ,2”-Terpyridine specific metals

The preparation of substituted terpyridine frameworks is well documented. Typical substitution patterns focus on functionahzation at the 4 -positions [26, 27]. Here, we will focus on preparations of terpyridines specifically modified at the 6- and 6 -positions, because substituents at these positions are positionally disposed to interact with metal-bound substrates. For clarity, this section will be limited to discussions of two common strategies for the synthesis of appended terpyridine ligands, namely early and late-stage ring assembly approaches. 

The single pyridine sites were designed with both a to- and a p-pyridine for varying metal specificity. Upon introduction of an iron(II) salt and subsequent binding of iron into two of the terpyridine-based sites, a square-shaped tetramer results with a metakligand ratio of 1 1 (Fig. 7.14). 

It should be noted that a number of SPC polymers which contain other heterocycles have been prepared, motivated by their promising optical or electrical properties. Examples include pyridine (65) [123], pyrrole (66) [124], oxadiazole (67) [125], selenophene (68) [126], benzo[2,l,3]thiadiazole (69) [127], benzo[2,l,3]selenadiazole (70) [126], perylene bisimide (71) [128], 1,4-diketo- pyrrolo[3,4-c]pyrrole-l,4-dione (72 and 73) [127,129], and triphenyleamine (74) [127] as part of the polymer backbone by SPC (Figure 19c). Specifically for metal complexation, porphyrin [130], difluoroboraindacene [131], bipyridine [132], phenanthroHne [113], terpyridine [133, 134], and the like [123] were embedded in the backbone. In this context, an interesting report was submitted by Rehahn et al., in which l,l -ferrocenyl units were incorporated into a PPP (Figure 22.20). Due to a low-energy barrier for rotation around the Cp-Fe-Cp axes (Cp = cyclopentadienyl), the obtained polymer 75 was assumed to take randomly coiled conformations [135]. 

We have described earlier the specific advantages of the 2,2 6, 2"-terpyridine (tpy) metalbinding domain over the related 2,2 -bipyridine or 1,10-phenanthroline domain [3]. Briefly, single stereo- and regio-isomers are formed when oligomers are assembled from the interaction of two tpy domains with a six-co-ordinate metal centre. In this article we will further explore the synthetic versatility of the tpy domain, and illustrate how this basic building block may be used to introduce almost any desired functionality into a metal complex. Specifically, we concentrate upon the introduction of a variety of functional types into the 4 -position of the ligand. 

The synthesis of homopolymers and block copolymers containing metal coordinating ligands is an important area of research due to the potential applications of these polymers in the fields of optics, electronics, and photonics. Specifically, the terpyridine group is very useful since it can act as a tridentate chelating ligand due to its strategically... 

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