Here we describe the synthesis of electron-rich PXX derivatives in which the energy levels of the excited states have been rigidly shifted through the insertion of imide groups. This has allowed the development of a new series of oxygen-doped photoredox-active chromophores with improved oxidizing and reducing properties. Capitalizing on the dehalogenation of organic halides as a model reaction, we could investigate the photooxidative and photoreductive potential of these molecules in model chemical transformations. Depending on the substrate, solvent and dye the reaction mechanism can follow different paths. This prompted us to consider the first chemoselective transformation protocol, in which two different C-Br bonds could be chemoselectively reacted through the sequential photoactivation of two different colorants.
The synthesis of a zig-zag oxygen-doped molecular rhombic ribbon has been achieved. This includes oxidative C-C and C-O bond formations that allowed the stepwise elongation and planarization of an oxa-congener of 2,7-periacenoacene. X-ray diffraction analysis corroborated the flat structure and the zig-zag topology of the O-doped edges. Photophysical and electrochemical investigations showed that the extension of the peri-xanthenoxanthene (PXX) into the molecular ribbon induces a noticeable shrinking of the molecular band gap devised by a rising of the HOMO energy level, a desirable property for p-type organic semiconductors.
Development of purely organic materials displaying room-temperature phosphorescence (RTP) will expand the toolbox of inorganic phosphors for imaging, sensing or display applications. While molecular solids were found to suppress non-radiative...
In this work, ac omprehensive account of the authors' synthetic efforts to prepareb orazino-doped hexabenzocoronenes by using the Friedel-Crafts-type electrophilic aromatic substitution is reported. Hexafluoro-functionalized aryl borazines, bearing an ortho fluoride leaving group on each of the N-and B-aryl rings,w as shown to lead to cascade-type electrophilica romatic substitution events in the stepwise CÀCbond formation, giving higher yields of borazinocoronenes than those obtained with borazine precursors bearing fluoride leavingg roups at the ortho positions of the B-aryl substituents. By using this pathway,a nu nprecedented boroxadizine-doped PAHf eaturing ag ulf-type periphery could be isolated,a nd itss tructure proven by single-crystal X-ray diffraction analysis. Mechanistic studies on the stepwise Friedel-Crafts-type cyclization suggestt hat the mechanism of the planarizationr eactionp roceeds through extension of the p system. To appraise the doping effect of the boroxadizine unit on the optoelectronic properties of topology-equivalent molecular graphenes, the all-carbon and pyrylium PAHa nalogues, all featuring ag ulf-type periphery, were also prepared. As already shown for the borazinodoped hexabenzocoronene, the replacement of the central benzene ring by its B 3 N 2 Oc ongener widens the HOMO-LUMO gap and dramaticallye nhances the fluorescence quantum yield.[a] J. Scheme1.Synthetic planarizationp rotocols for preparing borazino-doped hexabenzocoronenes 1 and 2.Figure 7. ESP surfaces mapped on the vdW surface up to an electrondensity of 0.05 electronbohr À3 for a) 11 and b) 18.Side (up) and top (bottom) view of the packingo fc )11 and d) 18.Atom colors:pink B, blue N, red O, gray C. Spacegroups: P2 1 /c and P1.
The synthesis of azig-zag oxygen-doped molecular rhombic ribbon has been achieved.T his includes oxidative C À Ca nd C À Ob ond formations that allowed the stepwise elongation and planarization of an oxa-congener of 2,7periacenoacene.X -rayd iffraction analysis corroborated the flat structure and the zig-zag topology of the O-doped edges. Photophysical and electrochemical investigations showed that the extension of the peri-xanthenoxanthene (PXX) into the molecular ribbon induces an oticeable shrinking of the molecular band gap devised by ar ising of the HOMO energy level, ad esirable property for p-type organic semiconductors.
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