Versatile Design Principles for Facile Access to Unstrained Conjugated Organoborane Macrocycles

A facile and versatile approach was developed to access ambipolar boron-containing macrocycles. Two examples of new conjugated cyclic motifs are presented with carbazole moieties as donors and borane moieties as acceptors embedded into the ring system. They were first predicted using computational methods. Possible targets with appropriately shaped π-conjugated bridges that minimize the overall ring strain were identified and their geometry was optimized by DFT methods. The synthetic demonstration was then accomplished using organometallic condensation reactions under high dilution conditions. The resulting monodisperse macrocycles provide important insights into the design principles necessary for the preparation of new unstrained macrocycles with interesting optical and electronic characteristics. The current research also offers a more general approach to conjugated ambipolar B/N macrocycles as a promising new family of (opto)electronic materials.