Structure–Property Studies of Bichromophoric, PAH-Functionalized Dithieno[3,2-b:2′,3′-d]phospholes

Boundaries of the Hyperconjugation from π-Extended Six-Membered Phosphorus Heterocycles

In the context of materials science, six-membered phosphorus heterocycles are intriguing building blocks due to their tunable properties through phosphorus post-functionalization and their unique hyperconjugative effects arising from the phosphorus substituents that contribute to further tuning the optoelectronic properties of the system. Seeking for the discovery of improved materials, the latter features have triggered an astonishing evolution of molecular architectures based on phosphorus heterocycles. Theoretical calculations showed that the hyperconjugation causes a reduction in the S₀-S₁ gap, which strongly depends on the nature of both the P-substituent and the π-conjugated core, but where are the limits? Outlining the hyperconjugative effects of six-membered phosphorus heterocycles would allow scientists to know how to design next-generation organophosphorus systems with enhanced properties. Herein, we discovered that, in cationic six-membered phosphorus heterocycles, an increase in the hyperconjugation does not affect the S₀-S₁ gap anymore; i.e., quaternizing the phosphorus atoms leads to properties that go beyond those provoked by hyperconjugative effects. DFT calculations revealed that the latter is particularly marked in phosphaspiro derivatives. Our detailed investigations spotlight the potential of π-extended systems based on six-membered phosphorus spiroheterocycles for accessing properties beyond those achieved to date through hyperconjugative effects, thus laying the groundwork for new research possibilities toward improved organophosphorus systems.

Synthesis, Optical, and Redox Properties of Regioisomeric Benzoheterocycles-Fused Pyrene

A new synthetic route toward the synthesis of benzo[b]phospholes- and benzo[b]siloles-fused pyrenes using a transition metal-catalyzed C-H bond activation is described. The compounds were fully characterized including X-ray diffraction. A combined experimental and theoretical study shows that both the heteroatom and the substitution pattern impact the optical and redox properties.

On the reactivity of P-chloro dithieno[3,2-b:2′,3′-d]phosphole oxide

The P-functionalization of dithieno[3,2-b:2′,3′-d]phosphole oxides via reaction of a P-chloro derivative with aromatic amines and alcohols is reported. The reactions proceed rapidly and provide the products in good yields, highlighting the synthetic versatility of the P-chloro dithienophosphole oxide toward effectively modifying the molecular scaffold without the need for elaborate phosphorus precursor syntheses. The resulting phosphinic amide and ester products show interesting photophysics that strongly depend on the nature of the P-substituent such as high luminescence quantum yields for the ester derivatives, as well as aggregation-induced enhanced emission for the amide derivative. The phosphinic amide species also shows intriguing self-assembly in the solid state via hydrogen bonding.

Structure–property studies of P-triarylamine-substituted dithieno[3,2-b:2′,3′-d]phospholes

The photo-physical and theoretical investigation of 10 novel donor–acceptor materials sheds new light on charge transfer in dithienophosphole oxide derivatives.

Synthesis and derivatization of highly-functionalized λ5-phospholes

A variety of peripheral functionalities are present in λ⁵-phospholes prepared by regiospecific [3+2] cycloaddition reactions of diphosphinoketenimines with electron-poor alkenes.