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Amino-borane functionalization is the key for isolating rare air-stable dihydrophenanthrene intermediates in stilbene photocyclization., The key intermediate, 4a,4b-dihydrophenanthrene (DPH), involved in the photocyclization of stilbene and derivatives is known to be unstable, and is therefore poorly characterized/understood. We have found that functionalising stilbenes with NMe2 and BMes2 groups can greatly enhance the stability of 4a,4b-DPHs, allowing quantitative isolation and full characterization of these rare species. Furthermore, we discovered that the new amino-borane decorated 4a,4b-DPHs can undergo thermal [1,5] H sigmatropic shift, forming isomers 4a,10a-DPHs. Both 4a,4b-DHPs and 4a,10a-DHPs are stable towards air and moisture, while only the former were found to undergo oxidative dehydrogenation upon irradiation at 365 nm under air, yielding brightly blue/green fluorescent NMe2 and BMes2 functionalised phenanthrene analogues. Control studies established that the trans-Mes2B–Ph–NMe2 unit is responsible for the stability of these isolated 4a,4b-DHPs and their [1,5]-H shift isomers.

Conjugated molecules have been explored as an important class of organic materials that are of paramount interest in organic electronics, such as organic light emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic solar cells. Although current studies frequently concentrate on conjugated polymers, small molecules areattractive in that they allow for facile fine-tuning of the HOMO and LUMO energy levels, which is crucial for enhancement of the overall performance of organic devices. Functionalization of conjugated organic systems with main group elements represents an active research area of current interest in the chemistry and matarial science community. One of the most often employed elements is the electron-deficient boron that features anempty p orbital that opens up a pathway to overlap with π orbitals of attached aryl groups. This interaction leads to unusual optical and electronic properties for organoborane compounds. The focus of this thesis is on the investigation of well-defined organoboraneoligomers and macrocycles.