Symmetric spirenes: promising building blocks for new generation opto-electronic materials

Spiroconjugated hydrocarbons, and in particular spirenes, show unique properties among the numerous π-conjugated materials; they are quite rigid systems, with a subsequently small excitation reorganization energy, and hence are excellent hole transporting materials. Furthermore they show chiroptical properties and an efficient intramolecular through-space charge transport capability, leading to thermally-activated delayed fluorescence. In this work an efficient protocol for computing different properties of spirenes is described and validated. This protocol is then employed to investigate the structural properties, intra- and inter-ring interactions, vibrational and optical spectra of a series of symmetric spirenes, whose properties are compared with the corresponding non-spiroconjugated cyclic hydrocarbons. The effect of oxidation and reduction is analysed in detail.