Abstract:Three synthetic methods towards semi‐planar triarylboranes with two aryl rings connected by a methylene bridge have been developed. The fine‐tuning of their stereoelectronic properties and Lewis acidities was achieved by introducing fluorine, methyl, methoxy, n‐butyl and phenyl groups either at their exocyclic or bridged aryl rings. X‐ray diffraction analysis and quantum‐chemical calculations provided quantitative information on the structural distortion experienced by the near planar hydro‐boraanthracene skel… Show more
“…[25][26][27][28] On the other hand, incorporation of an electron-deficient atom such as boron atom into a π-electron conjugated system results in a significant lowering of the LUMO level which leads to electron-deficient characteristics. [29][30][31][32][33][34][35][36][37][38] Fused triarylboranes are thus commonly used as dopants for electron-transporting materials, [39][40][41][42][43] anion-receptors, [44][45][46][47][48] Lewis acid catalysts, [49][50][51][52][53][54][55][56][57][58][59][60] and light-emitting materials. [61][62][63][64][65][66][67] From the known structures of boracyclic compounds, [44,68] boron-containing thiophene-fused systems are an especially fascinating class of functional materials thanks to their unique optical properties derived from the electron-accepting character of boron atom combined with electron-conduct...…”
Section: Introductionmentioning
confidence: 99%
“…On the other hand, incorporation of an electron‐deficient atom such as boron atom into a π‐electron conjugated system results in a significant lowering of the LUMO level which leads to electron‐deficient characteristics [29–38] . Fused triarylboranes are thus commonly used as dopants for electron‐transporting materials, [39–43] anion‐receptors, [44–48] Lewis acid catalysts, [49–60] and light‐emitting materials [61–67] .…”
A synthetic approach to two regioisomeric πelectron extended [1,4]thiaborins annulated with two benzothiophene units has been developed. The central thiaborin rings of the boracycles obtained exhibit different electronic properties; this is reflected in their different aromatic characters, boron Lewis acidity and UV-vis spectroscopic behavior. Thiaborins were converted to boron dipyrromethene (BODIPY) complexes. Their emission spectra exhibit two distinct bands resulting from 1 LE and 1 CT transitions. Strong near-infrared phosphorescence in Zeonex thin films at 77 K indicates efficient intersystem crossing and the formation of triplet states. Separation of HOMO and LUMO orbitals between boracyclic and BODIPY moieties facilitates electron transfer to a 1 CT state followed by a transition to the 3 LE triplet state located on the ligand. These unique properties of spiro thiaborin-BODIPY complexes were explored for their application as singlet-oxygen photosensitizers. They show excellent photocatalytic performance with singlet oxygen quantum yields reaching 77 % and full conversion of the model organic substrate achieved after 1.5 h with only 0.05 % mol catalyst load.
“…[25][26][27][28] On the other hand, incorporation of an electron-deficient atom such as boron atom into a π-electron conjugated system results in a significant lowering of the LUMO level which leads to electron-deficient characteristics. [29][30][31][32][33][34][35][36][37][38] Fused triarylboranes are thus commonly used as dopants for electron-transporting materials, [39][40][41][42][43] anion-receptors, [44][45][46][47][48] Lewis acid catalysts, [49][50][51][52][53][54][55][56][57][58][59][60] and light-emitting materials. [61][62][63][64][65][66][67] From the known structures of boracyclic compounds, [44,68] boron-containing thiophene-fused systems are an especially fascinating class of functional materials thanks to their unique optical properties derived from the electron-accepting character of boron atom combined with electron-conduct...…”
Section: Introductionmentioning
confidence: 99%
“…On the other hand, incorporation of an electron‐deficient atom such as boron atom into a π‐electron conjugated system results in a significant lowering of the LUMO level which leads to electron‐deficient characteristics [29–38] . Fused triarylboranes are thus commonly used as dopants for electron‐transporting materials, [39–43] anion‐receptors, [44–48] Lewis acid catalysts, [49–60] and light‐emitting materials [61–67] .…”
A synthetic approach to two regioisomeric πelectron extended [1,4]thiaborins annulated with two benzothiophene units has been developed. The central thiaborin rings of the boracycles obtained exhibit different electronic properties; this is reflected in their different aromatic characters, boron Lewis acidity and UV-vis spectroscopic behavior. Thiaborins were converted to boron dipyrromethene (BODIPY) complexes. Their emission spectra exhibit two distinct bands resulting from 1 LE and 1 CT transitions. Strong near-infrared phosphorescence in Zeonex thin films at 77 K indicates efficient intersystem crossing and the formation of triplet states. Separation of HOMO and LUMO orbitals between boracyclic and BODIPY moieties facilitates electron transfer to a 1 CT state followed by a transition to the 3 LE triplet state located on the ligand. These unique properties of spiro thiaborin-BODIPY complexes were explored for their application as singlet-oxygen photosensitizers. They show excellent photocatalytic performance with singlet oxygen quantum yields reaching 77 % and full conversion of the model organic substrate achieved after 1.5 h with only 0.05 % mol catalyst load.
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