A bis‐triarylborane tetracation (4‐Ar2B‐3,5‐Me2C6H2)‐C≡C−C≡C‐(3,5‐Me2C6H2‐4‐BAr2 [Ar=(2,6‐Me2‐4‐NMe3‐C6H2)+] (24+) shows distinctly different behaviour in its fluorimetric response than that of our recently published bis‐triarylborane 5‐(4‐Ar2B‐3,5‐Me2C6H2)‐2,2′‐(C4H2S)2–5′‐(3,5‐Me2C6H2‐4‐BAr2) (34+). Single‐crystal X‐ray diffraction data on the neutral bis‐triarylborane precursor 2 N confirm its rod‐like dumbbell structure, which is shown to be important for DNA/RNA targeting and also for BSA protein binding. Fluorimetric titrations with DNA/RNA/BSA revealed the very strong affinity of 24+ and indicated the importance of the properties of the linker connecting the two triarylboranes. Using the butadiyne rather than a bithiophene linker resulted in an opposite emission effect (quenching vs. enhancement), and 24+ bound to BSA 100 times stronger than 34+. Moreover, 24+ interacted strongly with ss‐RNA, and circular dichroism (CD) results suggest ss‐RNA chain‐wrapping around the rod‐like bis‐triarylborane dumbbell structure like a thread around a spindle, a very unusual mode of binding of ss‐RNA with small molecules. Furthermore, 24+ yielded strong Raman/SERS signals, allowing DNA or protein detection at ca. 10 nm concentrations. The above observations, combined with low cytotoxicity, efficient human cell uptake and organelle‐selective accumulation make such compounds intriguing novel lead structures for bio‐oriented, dual fluorescence/Raman‐based applications.

Three differentp erfluoroalkylated borafluorenes (F Bf)w ere prepared and their electronic and photophysical properties were investigated. The systemsh ave four trifluoromethyl moieties on the borafluorene moiety as well as two trifluoromethyl groups at the ortho positions of their exo-aryl moieties. They differ with regard to the para substituents on their exo-aryl moieties, being ap roton(F Xyl F Bf, F Xyl:2 ,6-bis(trifluoromethyl)phenyl), at rifluoromethyl group (F Mes F Bf, F Mes:2 ,4,6-tris(trifluoromethyl)phenyl) or ad imethylamino group (p-NMe 2-F Xyl F Bf, p-NMe 2-F Xyl:4-(dimethylamino)-2,6-bis(trifluoromethyl)phenyl), respectively.A ll derivatives exhibit extraordinarily low reduction potentials, comparable to those of perylenediimides. The most electron-deficient derivative F Mes F Bf wasa lso chemically reduced and its radicala nion isolated and characterized. Furthermore, all compounds exhibit very long fluorescent lifetimes of about 250 ns up to 1.6 ms; however, the underlying mechanismsresponsible for this differ.T he donor-substitutedd erivative p-NMe 2-F Xyl F Bf exhibitst hermally activated delayedf luorescence (TADF) from ac harge-transfer (CT) state, whereas the F Mes F Bf and F Xyl F Bf borafluorenese xhibit only weakly allowed locally excited (LE) transitions due to their symmetry and low transition-dipole moments.

Access to novel imine-substituted 1,2-azaborinines, as well as highly arylated boracyclohexa-3,5-dienes has been developed by ring expansion of boroles with diazoalkanes with varying degrees of steric bulk. The formation of a diazoalkane intermediate is also discussed for the reaction of ortho-brominated p-tolyl-azide with 1,2,3,4,5-pentaphenylborole. Structural details as well as UV/Vis spectroscopic and cyclic voltammetric data are provided. These boron-containing heterocycles have the potential to serve as building blocks for boron-containing materials.

In this combined experimental and theoretical study, a computational protocol is reported to predict the excited states in D‐π‐A compounds containing the B( F Xyl) 2 ( F Xyl = 2,6‐bis(trifluoromethyl)phenyl) acceptor group for the design of new thermally activated delayed fluorescence (TADF) emitters. To this end, the effect of different donor and π‐bridge moieties on the energy gaps between local and charge‐transfer singlet and triplet states is examined. To prove this computationally aided design concept, the D‐π‐B( F Xyl) 2 compounds 1 – 5 were synthesized and fully characterized. The photophysical properties of these compounds in various solvents, polymeric film, and in a frozen matrix were investigated in detail and show excellent agreement with the computationally obtained data. Furthermore, a simple structure–property relationship is presented on the basis of the molecular fragment orbitals of the donor and the π‐bridge, which minimize the relevant singlet–triplet gaps to achieve efficient TADF emitters.

Twod ifferentchromophores,n amely ad ipolar and an octupolar system,w ere prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and at riarylboranea st he acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar systeme xhibits a much higher two-photon brightness, and also better cell viability and enhanced selectivity for lysosomes comparedw ith the dipolar chromophore. Furthermore, both dyes were applied in two-photon excitedf luorescence( TPEF) live-cell imaging.[**] We are aware that the dipole moment m in our charged compounds is origin-dependenta nd not an observable quantity. [35] For simplification, we use the term dipole moment to describe the electron-density distribution in our chargedc ompounds. Thus,the terms dipole and octupole are used accordingly.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.org/10.

(Hetero)arene-fused boroles, ‘antiaromatic’ 2n-electron π-systems, more stable and more functionalizable than boroles, offer greater potential for a variety of applications.

We report four new luminescent tetracationic bis‐triarylborane DNA and RNA sensors that show high binding affinities, in several cases even in the nanomolar range. Three of the compounds contain substituted, highly emissive and structurally flexible bis(2,6‐dimethylphenyl‐4‐ethynyl)arene linkers (3: arene=5,5′‐2,2′‐bithiophene; 4: arene=1,4‐benzene; 5: arene=9,10‐anthracene) between the two boryl moieties and serve as efficient dual Raman and fluorescence chromophores. The shorter analogue 6 employs 9,10‐anthracene as the linker and demonstrates the importance of an adequate linker length with a certain level of flexibility by exhibiting generally lower binding affinities than 3–5. Pronounced aggregation–deaggregation processes are observed in fluorimetric titration experiments with DNA for compounds 3 and 5. Molecular modelling of complexes of 5 with AT‐DNA, suggest the minor groove as the dominant binding site for monomeric 5, but demonstrate that dimers of 5 can also be accommodated. Strong SERS responses for 3–5 versus a very weak response for 6, particularly the strong signals from anthracene itself observed for 5 but not for 6, demonstrate the importance of triple bonds for strong Raman activity in molecules of this compound class. The energy of the characteristic stretching vibration of the C≡C bonds is significantly dependent on the aromatic moiety between the triple bonds. The insertion of aromatic moieties between two C≡C bonds thus offers an alternative design for dual Raman and fluorescence chromophores, applicable in multiplex biological Raman imaging.

Narrow-band emission is essential for applicable circularly polarized luminescence (CPL) active materials in ultrahigh-definition CP-OLEDs. One of the most promising classes of CPL active molecules, helicenes, however, typically exhibit broad emission with a large Stokes shift. We present, herein, a design strategy capitalizing on intramolecular donor-acceptor interactions between nitrogen and boron atoms to address this issue. 1,4-B,N-embedded configurationally stable singleand double helicenes were synthesized straightforwardly. Both helicenes show unprecedentedly narrow fluorescence and CPL bands (full width at half maximum between 17-28 nm, 0.07-0.13 eV) along with high fluorescence quantum yields (72-85 %). Quantum chemical calculations revealed that the relative localization of the natural transition orbitals, mainly on the rigid core of the molecule, and small values of root-mean-square displacements between S 0 and S 1 state geometries, contribute to the narrower emission.