Rationally designed cationic phospha‐polyaromatic fluorophores were prepared through intramolecular cyclization of the tertiary ortho ‐(acene)phenylene‐phosphines mediated by Cu II triflate. As a result of phosphorus quaternization, heterocyclic phosphonium salts 1 c – 3 c , derived from naphthalene, phenanthrene, and anthracene cores, exhibited very intense blue to green fluorescence ( Φ em =0.38–0.99) and high photostability in aqueous medium. The structure–emission relationship was further investigated by tailoring the electron‐donating functions to the anthracene moiety to give dyes 4 c – 6 c with charge‐transfer character. The latter significantly decreases the emission energy to reach near‐IR region. Thus, the intramolecular phosphacyclization renders an ultra‐wide tuning of fluorescence from 420 nm ( 1 c ) to 780 nm ( 6 c ) in solution, extended to 825 nm for 6 c in the solid state with quantum efficiency of approximately 0.07. The physical behavior of these new dyes was studied spectroscopically, crystallographically, and electrochemically, whereas computational analysis was used to correlate the experimental data with molecular electronic structures. The excellent stability, water solubility, and attractive photophysical characteristics make these phosphonium heterocycles powerful tools in cell imaging.

The impact of integrating six-membered phosphorus heterocycles into a poly(hetero)aromatic materials is investigated. Mechanistic studies reveal the key synthetic requirements to embed the latter phosphorus heterocycles in polyaromatic molecules. DFT calculations indicate that introducing six-membered phosphorus rings into π-extended molecules induces a particular electron distribution over the π-extended system. Electrochemical investigations confirm that inserting six-membered phosphacycles into polyaromatics triggers ambipolar redox behavior. Steady-state spectroscopy reveals that fusing pyrroles with phosphorus-containing polyaromatic molecules induces fluorescence quantum yields as high as 0.8, whereas transient absorption spectroscopy demonstrates that fusing thiophenes promote the formation of non-emissive triplet-excited states. As a whole, the optoelectronic properties of fused phosphorus-containing materials give rise to promising performances in photoelectrochemical cells. Moreover, X-ray analyses confirm that the 3D arrangement in the solid state of polyaromatic systems containing six-membered phosphorus rings can be tailored through post-functionalization of the phosphorus center. Altogether, this investigation sets the bedrock for the design of a new generation of highly functional polyaromatic organophosphorus materials, keeping control over their electrochemical properties, fluorescence features, photo-induced excited states, and 3D molecular arrangement.

Oligoarenes are regarded as subunits of p-extended carbon nanoforms,s uch as graphene and nanotubes,w ith exceptional technological importance.F used arenes can thus providef undamental insight into the nature of the electronic properties of fused polyaromatic rings and pave the way for the design of extended graphene-like materials.However,large pextended arenes often show lowstability.Herein we report the straightforwardp reparation of linearly fused diphosphahexaarenes containing two six-membered phosphorus heterocycles. They are highly stable towards air,water,and light over months in both solution and the solid state.S ingle-crystal X-ray crystallography confirmed the molecular structure of all derivatives.I nvestigations of their optoelectronic properties revealed that the diphosphahexaarenes exhibit ambipolar redox behavior and high fluorescence quantum yields.Embedding six-membered phosphorus rings into large acenes thus opens up new opportunities for the investigation of polyaromatic systems. Angewandte ChemieCommunications

Under the conditions of dual activation catalysis with oxygen nucleophiles, β‐substituted naphthalenes were obtained from 1,2‐diethinyl arenes. Mechanistic studies, which include isotope labeling experiments, support that dual activation leads to β‐substituted naphthalenes, whereas α‐naphthalenes are formed by π activation only, and no gold acetylide or dual activation is involved in the formation of the α‐substituted products. Additional experiments on substrates that led to dibenzopentalenes support these mechanistic insights.

Oligoarenes are regarded as subunits of π‐extended carbon nanoforms, such as graphene and nanotubes, with exceptional technological importance. Fused arenes can thus provide fundamental insight into the nature of the electronic properties of fused polyaromatic rings and pave the way for the design of extended graphene‐like materials. However, large π‐extended arenes often show low stability. Herein we report the straightforward preparation of linearly fused diphosphahexaarenes containing two six‐membered phosphorus heterocycles. They are highly stable towards air, water, and light over months in both solution and the solid state. Single‐crystal X‐ray crystallography confirmed the molecular structure of all derivatives. Investigations of their optoelectronic properties revealed that the diphosphahexaarenes exhibit ambipolar redox behavior and high fluorescence quantum yields. Embedding six‐membered phosphorus rings into large acenes thus opens up new opportunities for the investigation of polyaromatic systems.

Diphosphahexaarenes are highly stable π‐extended frameworks containing two six‐membered phosphorus heterocycles that have emerged recently. Herein, we present a detailed investigation on the post‐functionalization reactions of their phosphorus centers with special emphasis on the selectivity of the processes and the impact of the phosphorus functionalizations into the physicochemical properties. These studies reveal that indeed the phosphorus atoms of the diphosphahexaarenes are readily available to be functionalized with quaternizing and oxidizing agents as well as borane groups without compromising the stability of the system. In addition, the optoelectronic properties of the diphosphahexaarenes are impacted by the phosphorus post‐modifications.

Soft and stretchable electronic devices are expected to offer technological advances in the field of robotics, human–machine interfacing, and healthcare. Employing biodegradable elastomers, hydrogels, and nontoxic conductors would add significant value to and minimize the ecological impact of such disposable and transient electronic applications. Here, the biodegradable and photo‐crosslinkable elastomer poly(glycerol sebacic) acrylate (PGSA) is characterized for its use in soft and stretchable electronics. Its mechanical properties are investigated in terms of their chemical composition and compared to commonly used gelatin hydrogels. Furthermore, these materials are combined with interconnects made of liquid Galinstan in order to create functional substrates with certified biodegradability under ISO standards. The combination of these materials produces elastic circuit boards that act as soft platforms for body‐mounted sensors or biodegradable stretchable light‐emitting devices. These soft platforms reveal linear elongations at a break of 130% to 350% and similar moduli to nondegradable elastomers and human tissue, without any decrease in conductivity. Advanced applications in biofriendly packaging, soft robotics, and healthcare will greatly benefit from these biodegradable devices.

The chemistry of linearly fused systems based on sixmembered phosphorus heterocycles is currently experiencing an astonishing evolution. Even though the phosphorus analogs of naphthalene and anthracene were first synthesized in the late 1960s, laterally fused phosphorus heterocycles have recently demonstrated outstanding performances as biomarkers, [a] Scheme 2. Synthetic route to afford diphosphahexaarenes: a) CsF, Pd(PPh 3 ) 4 , CuI, 50°C/(8-bromonaphthalen-1-yl)tributylstannane; b) 1. tBuLi, -78°C, 2. PhPCl 2 , 3. H 2 O 2 , 0°C.