MULTIFARENES: NEW MODULAR CAVITANDS FOR HOST-GUEST CHEMISTRY

Most macrocyclic host molecules are formed by cyclooligomerization of a specific building block, which dictates their binding properties, substitution patterns, functionalization and solubility. We reasoned that the design of modular cavitands containing multiple building blocks would offer interesting opportunities in supramolecular architecture, catalysis, surface chemistry, chemical analysis, molecular labeling and separation technologies.

Our multifarenes[m,n] (MFs) represent a new family of modular cavitands, which are based on two different building blocks, with m and n representing the number of repeating subunits.¹ The multifarenes are conveniently prepared by three alternative synthetic approaches that provide modularity, generality and scalability. The simplest members of this family bind metals at their heteroatom portals, but their cavity is too flexible and too small to bind organic guest molecules. Our second generation of more rigid MFs were achieved via condensation reactions between substituted bis-formyl-phenols and aromatic 1,2-diamines. The new compounds are capable of induced fit to guest molecules. Other related macrocycles include polyimino-phenols and their partially or fully reduced analogs. We also show that the exchange of different functional groups at the molecular rim alters their positions under kinetic control. Finally, we present here an interesting interconversion between cyclic (thio)carbamate and cyclic (thio)urea derivatives of MF[2,2].

1. Parvari, G.; Annamalai, S.; Borovoi, I.; Chechik, H.; Botoshansky, M.; Pappo, D.; Ehud Keinan, E. Chem. Commun. 2014, 50, 2494-2497.