Modular supramolecular dimerization of optically tunable extended aryl viologens.

Magdalena Olesińska, Guanglu Wu, Silvia Gómez-Coca, Daniel Antón-García, Istvan Szabó, Edina Rosta, Oren A Scherman

OAI: oai:www.repository.cam.ac.uk:1810/300467 • DOI: 10.17863/CAM.47539

Cucurbit[8]uril (CB[8]) mediated assembly of extended aryl viologens (EVs) into optically tunable dimers is reported for the first time. We show that the modular design and synthesis of a new class of π-conjugated viologen derivatives with rigid aromatic or heteroaromatic bridging units as well as electron donating molecular recognition motifs enable their self-assembly into 2 : 2 complexes with CB[8]. The quantitative dimerization process involving these two molecular components in an aqueous solution enables excimer-like interactions between closely packed charged guests giving rise to distinct spectroscopic behavior. The nature of these dimers (CB[8]2·(EV[X]R)2) in the ground and excited states was characterized by NMR, isothermal titration calorimetry, and steady-state spectroscopic measurements.