Deboronation-induced ratiometric emission sensing of fluoride by 1,3,5-tris-(o-carboranyl-methyl)benzene

Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing ‘turn-on’ emissive variation

“…In particular, the broad singlet peaks in the region of 3.5-2.3 ppm in the 1 H{ 11 B} NMR spectrum (assigned to 10H atoms in total) conrmed the presence of the -BH groups of the o-carborane cage. In addition, two distinct signals observed at 88 and 86 ppm in the 13 C NMR spectrum were attributed to the carbon atoms in o-carborane. The 1 H{ 11 B} NMR spectrum of nido-Cz exhibited upeld-shied peaks relative to those of closo-Cz due to the anionic nature of nido-o-carborane.…”

“…S1-S5 in the ESI †) and elemental analysis. The 1 H{ 11 B} and 13 C NMR spectra of closo-Cz displayed resonances corresponding to the 9methyl-9H-carbazole moiety. In particular, the broad singlet peaks in the region of 3.5-2.3 ppm in the 1 H{ 11 B} NMR spectrum (assigned to 10H atoms in total) conrmed the presence of the -BH groups of the o-carborane cage.…”

“…Among the icosahedral boron-cluster compounds, closo-orthocarborane (1,2-dicarba-closo-dodecaborane) has recently attracted extensive attention as a functional moiety for applied materials in the elds of optoelectronic devices [1][2][3][4] and chemodosimeter/sensors [5][6][7][8][9][10][11][12][13][14][15][16][17] because o-carborane-appended p-aromatic uorophores can exhibit unique photophysical properties [2][3][4] and have reasonable thermal and electrochemical stabilities. [1][2][3]26,66 Such intriguing features arise from the strong electron withdrawing nature attributable to the carbon atoms of the cluster, which originates from the high polarisability of their s-aromaticity.…”

“…This conversion to nido-o-carborane induces a severe counter-current ICT transition since its electronic role in the dyad system changes to a donor (D) due to the anionic nature of the nido-species. [5][6][7][8][9][10][11][12][13][14][15][16][73][74][75][76] Indeed, the photophysical characteristics of closo-o-carborane appended onto various organic luminophores have been found to change dramatically during conversion to the nido-species in the presence of nucleophilic anions, suggesting its potential as a functional unit applicable to visualised sensory materials. [5][6][7][8][9][10][11][12][13][14][15][16] Thus, to further investigate such changes in photophysical properties via the conversion of closo-o-carborane to the anionic nido-o-species by deboronation with a nucleophilic anion, we strategically designed and prepared two carbazole-based o-carboranyl compounds, in which closo-or nido-o-carborane is appended to the C3-position of 9-methyl-9H-carbazole (closo-Cz and nido-Cz, respectively, Scheme 1).…”

Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9H-carbazole-Based ortho-Carboranyl Luminophores

“…Recent research has shown that the ICT-based luminescence characteristics of D‒A dyads are dramatically affected by the electronic environment of the o -carborane cage. For example, the photophysical properties are drastically altered by the deboronation of a closo - o -carborane to give a nido - o -carborane (nest-like structure, where one boron atom is removed from the icosahedron) [ 33 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ], as the anionic character of the nido -type structure interrupts the ICT transition [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. The intrinsic differences between the electronic properties of closo - and nido - o -carboranes have been investigated, providing inspiration as novel molecular scaffolds for chemodosimeter materials.…”