Carbon allotropes built from rings of two-coordinate atoms, known as cyclo[ n ]carbons, have fascinated chemists for many years, but until now they could not be isolated or structurally characterized because their high reactivity. We generated cyclo[18]carbon (C 18 ) using atom manipulation on bilayer NaCl Cu(111) at 5 kelvin by eliminating carbon monoxide a cyclocarbon oxide molecule, C 24 O 6 . Characterization high-resolution atomic force microscopy revealed polyynic structure with...

Cyclo[18]carbon (C18, a molecular carbon allotrope) can be synthesized by dehalogenation of bromocyclocarbon precursor, C18Br6, in 64% yield, atomic manipulation on sodium chloride bilayer Cu(111) at 5 K, and imaged high-resolution force microscopy. This method generating C18 gives higher yield than that reported previously from the cyclocarbon oxide C24O6. The experimental images were compared with simulated for four theoretical model geometries, including possible bond-angle alternation:...

The development of stable and tunable polycyclic aromatic compounds (PACs) is crucial for the advancement organic optoelectronics. Conventional PACs, such as acenes, often suffer from poor stability due to photooxidation oligomerization, which are linked their frontier molecular orbital energy levels. To address these limitations, we designed synthesized a new class π-expanded indoloindolizines by merging indole indolizine moieties into single framework. We developed scalable synthetic...

Thin films of 5,11-dicyano-6,12-diphenyltetracene (TcCN) have been studied for their ability to undergo singlet exciton fission (SF). Functionalization tetracene with cyano substituents yields a more stable chromophore favorable energetics exoergic SF (2E(T1)-E(S1)=-0.17 eV), where S1 and T1 are triplet excitons, respectively. As result tuning the triplet-state energy, is faster in TcCN relative corresponding endoergic process tetracene. proceeds two time constants film samples (τ=0.8±0.2 ps...

New strategies for synthesizing polyyne polyrotaxanes are being developed as an approach to stable carbyne "insulated molecular wires". Here we report active metal template route [3]rotaxanes, using dicobalt carbonyl masked alkyne equivalents. We synthesized two both with the same C28 dumbbell component, one a phenanthroline-based macrocycle and 2,6-pyridyl cycloparaphenylene nanohoop. The thermal stabilities of rotaxanes were compared that naked in decalin at 80 °C, nanohoop rotaxane was...

Triplet-triplet annihilation photon upconversion (TTA-UC) systems hold great promise for applications in energy, 3D printing, and photopharmacology. However, their optimization remains challenging due to the need precise tuning of sensitizer annihilator concentrations under oxygen-free conditions. This study presents an automated, high-throughput platform discovery TTA-UC systems. Capable performing 100 concentration scans just two hours, generates comprehensive maps critical parameters,...

A versatile, two-step synthesis of highly substituted, cyano-functionalized diaryltetracenes has been developed, starting from easily accessible tetraaryl[3]cumulenes. This unprecedented transformation is initiated by [2+2] cycloaddition tetracyanoethylene (TCNE) to the proacetylenic central double bond cumulenes give an intermediate zwitterion, which after electrocyclization cascade and dehydrogenation yields 5,5,11,11-tetracyano-5,11-dihydrotetracenes in a one-pot procedure. subsequent...

Pyropheophorbide-a methyl ester (PPa-OMe) has been modified by attaching electron-donor and -acceptor groups to alter its linear nonlinear optical properties. Regioselective bromination of the terminal vinyl position Suzuki coupling were used attach a 4-(N,N-diethylaminophenyl) group. The electron-acceptor dicyanomethylene was attached at cyclic ketone through Knoevenagel condensation. Four different derivatives PPa-OMe, containing either or groups, both, converted hydrophilic bis-TEG amides...

Singlet fission (SF) holds great promise for current photovoltaic technologies, where tetracenes, with their relatively high triplet energies, play a major role application in silicon-based solar cells. However, the SF efficiencies tetracene dimers are low due to unfavorable energetics of singlet and energy levels. In solid state, exhibits yields formation through SF, raising interest about underlying mechanisms. To address this discrepancy, we designed prepared novel molecular system based...

Cyano-substituted tetracenes (5,11-dicyano-6,12-diphenyltetracene, Tet) undergo exoergic singlet fission (SF), a spin-allowed photophysical process that generates pair of triplet excitons from one exciton. To elucidate substituent effects on SF, we have measured the SF dynamics and yields thin films, formed by Tet bearing hydrogen (H), methyl (Me), fluoro (F), trimethylsilyl (TMS) substituents p-phenyl positions 3 9 tetracene core, time-resolved spectroscopy in vis-NIR IR regions. The H-,...

Abstract A variety of asymmetrically donor–acceptor‐substituted [3]cumulenes (buta‐1,2,3‐trienes) were synthesized by developed procedures. The activation barriers to rotation Δ G ≠ measured variable temperature NMR spectroscopy and found be as low 11.8 kcal mol −1 , in the range for around sterically hindered single bonds. central CC bond push–pull‐substituted [3]cumulene moiety is shortened down 1.22 Å X‐ray crystallography, leading a substantial length alternation (BLA) up 0.17 Å. All...

Bulky photolabile masked alkyne equivalents (MAEs) are needed for the synthesis of polyyne polyrotaxanes, as insulated molecular wires and stabilized forms linear polymeric allotrope carbon, carbyne. We have synthesized a novel MAE based on phenanthrene compared it with an indane-based MAE. Photochemical unmasking model compounds was studied at different wavelengths (250 350 nm), key products were identified by NMR spectroscopy X-ray crystallography. UV irradiation 250 nm leads to both MAEs....

Abstract Polyyne polyrotaxanes, encapsulated cyclocarbon catenanes and other fascinating mechanically interlocked carbon‐rich architectures should become accessible if masked alkyne equivalents (MAEs) can be developed that are large enough to prevent unthreading of a macrocycle, cleanly unmasked under mild conditions. Herein, we report the synthesis new bulky MAE based on t ‐butylbicyclo[4.3.1]decatriene. This was used synthesize polyyne [2]rotaxane masked‐polyyne [3]rotaxane by...

Extended triisopropylsilyl end-capped polyynes have been prepared from the corresponding tetracobalt complexes by removing complexed dicobalt tetracarbonyldiphenylphosphinomethane (Co2(CO)4dppm) moieties. Unmasking of this "masked alkyne equivalent" was achieved under mild conditions with elemental iodine at room temperature, making it possible to obtain fragile up 20 contiguous sp-hybridized carbon atoms. The Co2(CO)4dppm moiety has a strong geometric and steric effect on polyyne but does...

Abstract Wir berichten über eine vielseitig anwendbare, zweistufige Synthese hochsubstituierter, cyanofunktionalisierter Diaryltetracene ausgehend von leicht zugänglichen Tetraaryl[3]cumulenen. Diese beispiellose Umsetzung beginnt mit der [2+2]‐Cycloaddition Tetracyanoethylen (TCNE) an die proacetylenische zentrale Doppelbindung Cumulene unter Bildung eines zwitterionischen Zwischenprodukts, welches Elektrocyclisierungskaskade und nachfolgende Dehydrierung in einer Eintopfreaktion...

Abstract Thin films of 5,11‐dicyano‐6,12‐diphenyltetracene ( TcCN ) have been studied for their ability to undergo singlet exciton fission (SF). Functionalization tetracene with cyano substituents yields a more stable chromophore favorable energetics exoergic SF (2E(T 1 )−E(S )=−0.17 eV), where S and T are triplet excitons, respectively. As result tuning the triplet‐state energy, is faster in relative corresponding endoergic process tetracene. proceeds two time constants film samples...

Abstract A four‐step synthesis of substituted 5,11‐dicyano‐6,12‐diaryltetracenes was developed, starting from readily available para ‐substituted benzophenones. The key step this straightforward route is the complex cascade reaction between tetraaryl[3]cumulenes and tetracyanoethene (TCNE) resulting in 5,5,11,11‐tetracyano‐5,11‐dihydrotetracenes. mechanism transformation reinvestigated by means theoretical calculations. target tetracenes were obtained a newly developed...

Abstract Singlet fission (SF) holds great promise for current photovoltaic technologies, where tetracenes, with their relatively high triplet energies, play a major role application in silicon‐based solar cells. However, the SF efficiencies tetracene dimers are low due to unfavorable energetics of singlet and energy levels. In solid state, exhibits yields formation through SF, raising interest about underlying mechanisms. To address this discrepancy, we designed prepared novel molecular...

The development of stable and tunable polycyclic aromatic compounds (PACs) is crucial for advancing organic optoelectronics. Conventional hydrocarbons (PAHs), such as acenes, often suffer from poor stability due to photooxidation oligomerization, which are linked their frontier molecular orbital energy levels. To address these limitations, we have designed synthesized a new class π-expanded indoloindolizines by merging indole indolizine moieties into single framework. Guided the...

Electronic absorption and magnetic circular dichroism were recorded for five cyclophanes with ethano bridges: [2.2]paracyclophane, (1,2,4)[2.2.2]cyclophane, (1,2,4;1,2,5)[2.2.2]cyclophane, (1,2,3,4,5,6)(1,2,3,4,5,6)cyclophane, trans-[2.2]metacyclophane. Spectral structural analyses based on geometry optimization calculations of transition energies, carried out using density functional theory methods. The assignments have been proposed several electronic transitions observed in the region...

We report visible color changes and new intense, bathochromically shifted bands in electronic absorption spectra that reach into the near‐infrared region (up to 862 nm) upon protonation of nine pentafulvene expanded pentafulvalene derivatives. This phenomenon can only be explained by formation carbocations with highly delocalized charges. Solution p K a values organic solvents were determined, making use method relative basicity measurements. All seven 6‐phenylpentafulvenes are weak bases,...

We have developed a one‐step synthesis of 5,6‐dicyano‐7‐(diphenylvinyl)‐7 H ‐benzo[ c ]fluorenes, starting from easily accessible tetraaryl[3]cumulenes and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). In the proposed mechanism, this transformation is initiated by single‐electron transfer cumulene to DDQ with subsequent ring closure. next step, [4+2] cycloaddition an additional molecule followed formed cycloadducts, which provides new 5,6‐dicyanobenzo[ ]fluorene derivatives in fair good...