Bowl-shaped aromatic compounds, namely buckybowls constitute a family of curved polycyclic aromatic carbons along with fullerenes and carbon nanotubes. Doping of heteroatoms to the carbon frameworks ...of such aromatic compounds drastically modulates their physical and chemical properties. In contrast to nitrogen-doped azafullerenes or carbon nanotubes, synthesis of azabuckybowls, nitrogen-doped buckybowls, remains an unsolved challenging task. Here we report the first enantioselective synthesis of a chiral azabuckybowl, triazasumanene. X-ray crystallographic analysis confirmed that the doping of nitrogen induces a more curved and deeper bowl structure than in all-carbon buckybowls. As a result of the deeper bowl structure, the activation energy for the bowl inversion (thermal flipping of the bowl structure) reaches an extraordinarily high value (42.2 kcal per mol). As the bowl inversion corresponds to the racemization process for chiral buckybowls, this high bowl inversion energy leads to very stable chirality of triazasumanene.
The synthesis of an iodine-doped sumanene, which represents the first example of halogen-doped buckybowls, is described. Pristine trithiasumanene, trisilasumanene and the hitherto unknown parent ...triselenasumanene, three interesting heterobuckybowls with significant synthetic challenges, were efficiently prepared from the iodine-doped sumanene through non-pyrolytic conditions. This work demonstrates the high potential of hypervalent iodines embedded in extended π-conjugated systems for the synthesis of novel curved and planar polycyclic aromatic hydrocarbons.
A three-step synthesis of C 3-symmetric trisilasumanene and trigermasumanene, heteroanalogues of the π-bowl sumanene, was achieved using a threefold rhodium-catalyzed cyclodehydrogenation of Si/Ge–H ...and C–H bonds as the key step. Trigermasumanene was proven to adopt a planar geometry by single crystal X-ray diffraction for the first time. The optical properties were also investigated by UV–vis and fluorescence spectroscopy.
A palladium-catalyzed synthesis of dibenzothiophenes from 2-biphenylthiols is described. This highly efficient reaction employs a simple PdCl2/DMSO catalytic system, in which PdCl2 is the sole metal ...catalyst and DMSO functions as an oxidant and solvent. This transformation has broad substrate scope and operational simplicity and proceeds in high yield. The synthetic utility was demonstrated by the facile synthesis of helical dinapthothiophene 3 and an eminent organic semiconductor DBTDT 4. Importantly, highly strained trithiasumanene 5, a buckybowl of considerable synthetic challenge, was observed under this catalytic system.
Prostheses and orthoses are common assistive devices to meet the biomechanical needs of people with physical disabilities. The traditional fabrication approach for prostheses or orthoses is a ...material-wasting, time-consuming, and labor-intensive process. Additive manufacturing (AM) technology has advantages that can solve these problems. Many trials have been conducted in fabricating prostheses and orthoses. However, there is still a gap between the hype and the expected realities of AM in prosthetic and orthotic clinics. One of the key challenges is the lack of a systematic framework of integrated technologies with the AM procedure; another challenge is the need to design a prosthetic or orthotic product that can meet the requirements of both comfort and function. This study reviews the current state of application of AM technologies in prosthesis and orthosis fabrication, and discusses optimal design using computational methods and biomechanical evaluations of product performance. A systematic framework of the AM procedure is proposed, which covers the scanning of affected body parts through to the final designed adaptable product. A cycle of optimal design and biomechanical evaluation of products using finite-element analysis is included in the framework. A mature framework of the AM procedure and sufficient evidence that the resulting products show satisfactory biomechanical performance will promote the application of AM in prosthetic and orthotic clinics.
Unsymmetrical disulfides have been effectively prepared through thiol exchange with symmetrical disulfides employing a simple PdCl2/DMSO catalytic system. The given method features excellent ...functional group tolerance, a broad substrate scope, and operational simplicity. This reaction is especially useful for late-stage functionalization of bioactive scaffolds such as peptides and pharmaceuticals. Disulfide-containing organic dyes have also been prepared. This transformation could be extended to thiol–diselenide or thiol–ditelluride exchange affording RS–SeR′ or RS–TeR′.
A four-step synthesis of the C3-symmetric parent 1,5,9-triazacoronene (TAC) and its derivatives was achieved using a three-fold Bischler-Napieralski cyclization as the key step. The single-crystal ...X-ray diffraction of 1b (R = n-Bu) demonstrates that the azacoronene core is perfectly co-planar and the molecules adopt a favorable 2-D "brick-wall" arrangement with strong π-π interactions. The unique stacking, tunable photophysical and electronic properties, and high thermal stability should make them promising candidates for emissive and electron-transport materials.
A series of π-conjugated compounds ending with 9,9-diethyl-1-phenyl-1,9-dihydrofluoreno2,3-
d
imidazole were conveniently synthesized by condensation of the key intermediate 9,9-diethyl-N
2
...-phenyl-9H-fluorene-2,3-diamine with the corresponding symmetric aryl phthalaldehydes under very mild conditions. The structures of these compounds were confirmed by
1
H NMR,
13
C NMR, and HRMS. Their UV-Vis spectroscopy data, fluorescent spectroscopy data, and further details of the electronic properties from cyclic voltammetry measurements and theoretical calculations were studied. Most compounds possess good fluorescence-emitting ability with quantum yield of fluorescence values in the region of 0.36–0.92 and display emission within 449–513 nm depending on the molecular nature.
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