Here, we report the synthesis of BN-doped graphenoid
nanoribbons,
in which peripheral carbon atoms at the zigzag edges have been selectively
replaced by boron and nitrogen atoms as BN and NBN motifs. This includes
high-yielding ring closure key steps that, through N-directed borylation reaction using solely BBr3, allow
the planarization of meta-oligoarylenyl precursors,
through the formation of B–N and B–C bonds, to give
ter-, quater-, quinque-, and sexi-arylenyl nanoribbons. X-ray single-crystal
diffraction studies confirmed the formation of the BN and NBN motifs
and the zigzag-edged topology of the regularly doped ribbons. Steady-state
absorption and emission investigations at room temperature showed
a systematic bathochromic shift of the UV–vis absorption and
emission envelopes upon elongation of the oligoarylenyl backbone,
with the nanoribbon emission featuring a TADF component. All derivatives
displayed phosphorescence at 77 K. Electrochemical studies showed
that the π-extension of the peri-acenoacene
framework provokes a lowering of the first oxidative event (from 0.83
to 0.40 V), making these nanoribbons optimal candidates to engineer p-type organic semiconductors.
2D materials attracted tremendous interest since the discovery of graphene, because of their unique optical/electronic/mechanical properties, and their manipulable bidimensional morphology. Since forthcoming technologies require a stringent yet faceted portfolio...
The Cover Feature shows the color changes achieved, upon oxidation, by newly synthesized electrochromic oxygen‐doped small molecules. The crucial moieties are furano and pyrano. Incorporation of these groups into other organic molecules can be used to greatly expand the library of electrochromic small molecules, giving very good control over color transition observed. Such controlled color changes could take electrochromism from the niche applications it currently occupies, to the wider world. Cover design by Adriana Lopez‐Biagi. More information can be found in the Full Paper by D. Bonifazi et al.
In this work, we report the synthesis of O‐doped naphthalene‐based electrochromes. Exploiting the CuO‐mediated Pummerer oxidative cycloetherification reaction, a series of 1,4‐ and 1,5‐disubstituted naphthalene‐cored dipyrano, difurano, and furano‐pyrano polycyclic aromatic hydrocarbons (PAHs) have been prepared. Steady‐state UV‐Vis absorption and emission investigations showed that the spectroscopic profile strongly depends on the O‐doping topology, with the dipyrano and the difurano derivatives demonstrating the most red‐shifted and blue‐shifted electronic transition, respectively. Computational investigations revealed that the cycloetherification reaction raises the HOMO energy level (while the LUMO remains largely unaffected), with the dipyrano derivatives displaying the highest values. Spectroelectrochemical measurements showed that, depending on the O‐topology and the type of O‐ring, different electrochromic responses could be obtained with colour transitions featuring high contrasts involving yellow, pink, orange or blue colours.
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