We highlight recent developments in the synthesis, optical and electronic properties of 3-coordinate boron compounds and their applications in materials.

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.

The tetracationic diketopyrrolopyrrole compound 5M exhibits a σ2 value of 4560 GM at 740 nm.

The stability of tetracationic triarylboranes in dilute aqueous solution wasi nvestigated by tuning the steric demando ft he linker in a(