Multifunctional “Clickates” as Versatile Extended Heteroaromatic Building Blocks: Efficient Synthesis via Click Chemistry, Conformational Preferences, and Metal Coordination

TLDR: The extended heteroaromatic BTP scaffold should prove useful for the design of responsive foldamer backbones and the preparation of new magnetic and emissive materials.

Abstract: Click chemistry has been uti- lized to access 2,6-bis(1-aryl-1,2,3-tri- Anes (BTPs) as versatile extended heteroaromatic building blocks for their exploitation in supra- molecular chemistry, in particular fol- damer and ligand design. In addition to their high-yielding synthesis using Cu I - catalyzed Huisgen-type 1,3-dipolar cy- cloaddition reactions the formed tri- A moieties constitute an integral part of the BTP framework and encode both its pronounced conformational preferences as well as its chelating abil- ity. A diverse set of symmetrical and non-symmetrical BTPs carrying elec- tron-donating and -withdrawing sub- stituents at both terminal aryl and the central pyridine moieties has efficiently been synthesized and could further- more readily be postfunctionalized with amphiphilic side chains and por- phyrin chromophores. In both solution and solid state, the BTP scaffold adopts a highly conserved horseshoe- like anti-anti conformation. Upon pro- tonation or metal coordination, the BTP scaffold switches to the chelating syn-syn conformation. Iron and europi- um complexes have been prepared, successfully characterized by single- crystal X-ray diffraction analysis, and investigated with regard to their spin state and luminescent properties. The extended heteroaromatic BTP scaffold should prove useful for the design of responsive foldamer backbones and the preparation of new magnetic and emis- sive materials.