Twisted carbazoles and shallow dihedral angles provide a defence against dimer formation that adversely affects OLED performance.

Three related aromatic [22] heteroporphyrins have been synthesized and characterized, with the target of achieving NIR absorption. The propensity of these smallest π-conjugated macrocycles to absorb in the NIR region is benefitted from the fusion/annelation of the precursor heterocycles.

The synthesis of a new class of functionalized organophosphates, potential building units in materials and zeolite chemistry, has been reported.

The balance between strain relief and aromatic stabilization dictates the form and function of non-planar π-aromatics. Overcrowded systems are known to undergo geometric deformations, but the energetically favourable π-electron delocalization of their aromatic ring(s) is typically preserved. In this study we incremented the strain energy of an aromatic system beyond its aromatic stabilization energy, causing it to rearrange and its aromaticity to be ruptured. We noted that increasing the steric bulk around the periphery of π-extended tropylium rings leads them to deviate from planarity to form contorted conformations in which aromatic stabilization and strain are close in energy. Under increasing strain, the aromatic π-electron delocalization of the system is broken, leading to the formation of a non-aromatic, bicyclic analogue referred to as ‘Dewar tropylium’. The aromatic and non-aromatic isomers have been found to exist in rapid equilibrium with one another. This investigation demarcates the extent of steric deformation tolerated by an aromatic carbocycle and thus provides direct experimental insights into the fundamental nature of aromaticity.