Reduction of 2-(BMes2)pyrene (B1) and 2,7-bis(BMes2)pyrene (B2) gives rise to anions with extensive delocalization over the pyrenylene bridge and between the boron centers at the 2- and 2,7-positions, the typically unconjugated sites in the pyrene framework. One-electron reduction of B2 gives a radical anion with a centrosymmetric semiquinoidal structure, while two-electron reduction produces a quinoidal singlet dianion with biradicaloid character and a relatively large S0-T1 gap. These results have been confirmed by cyclic voltammetry, X-ray crystallography, DFT/CASSCF calculations, NMR, EPR, and UV-vis-NIR spectroscopy.

R–Ph–B(FMes)2 compounds exhibit low reduction potentials, bright emission, a TICT state and unusual long-lived phosphorescence at low temperature.

Abstract:Three water-soluble tetracationic quadrupolar chromophores comprising two three-coordinate boron -acceptor groups bridged by thiophene-containing moieties were synthesised for biological imaging applications. The derivative 3 containing the bulkier 5-(3,5-Me2C6H2)-2,2′-(C4H2S)2-5′-(3,5-Me2C6H2) bridge is stable over a long period of time, exhibits a high fluorescence quantum yield and strong one-(OPA) and two-photon absorption (TPA), with a TPA cross-section of 268 GM at 800 nm in water. Confocal laser scanning fluorescence microscopy studies in live cells indicate localisation of the chromophore at the mitochondria; moreover, cytotoxicity measurements prove biocompatibilty. Thus, chromophore 3 has excellent potential for one-and two-photon excited fluorescence imaging of mitochondrial function in cells.

. (2015) 'DA triarylboron compounds with tunable pushpull character achieved by modication of both the donor and acceptor moieties.', Chemistry : a European journal., 21 (1). pp. 177-190. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

Boroles with a fluoromesityl group on the B atom have greatly improved air stability compared to their mesityl analogues.

We report a general and selective method to synthesize 2,7-disubstituted pyrene derivatives containing two different substituents by sequential Ir-catalyzed borylation and substitution chemistry. To demonstrate the utility of our approach, we synthesized 2-cyano-7-(N,N-diethylamino)pyrene (3), a pyrene analogue of the widely studied chromophore 4-(N,N-dimethylamino)benzonitrile (DMABN). Compound 3 and the monosubstituted compounds 2-(N,N-diethylamino)pyrene (1) and 2-cyanopyrene (2) have been structurally characterized. Their electronic and optical properties have been studied by a combination of absorption and emission spectroscopies, lifetime and quantum yield measurements, and modeling by DFT and TD-DFT. The photophysical properties of 3 are compared to those of DMABN and 2-cyano-7-(N,N-dimethylamino)-4,5,9,10-tetrahydropyrene, and we show that 2,7-disubstituted pyrene is a moderately effective π-bridge for the construction of donor-acceptor compounds. It is also shown that donor or acceptor groups are only effective at the 2,7-positions of pyrene if they are suitably strong, leading to a switch in the energetic ordering of the HOMO-1 and HOMO or the LUMO and LUMO+1 of pyrene, respectively.

The importance of the directional dependence of magnetic susceptibility in magnetic resonance and of electric susceptibility in the optical spectroscopy of lanthanide coordination complexes is assessed. A body of more reliable shift, relaxation and optical emission data is emerging for well-defined isostructural series of complexes, allowing detailed comparative analyses to be undertaken. Such work is highlighting the limitations of the current NMR shift and relaxation theories, as well as emphasising the absence of a compelling theoretical framework to explain optical emission phenomena.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. [a,b] Robert M. Edkins, [a,b] Laura J. Sewell, [a] Andrew Beeby, [a] Andrei S. Batsanov, [a] Katharina Fucke, [b,c]