Highly symmetric Ln(III) boron-containing macrocycles as bright fluorophores for living cell imaging

Boron-assisted highly symmetric lanthanide (Ln) macrocycles, (eta(2)-catechol-mu-catecholborate)(3)Ln (Ph3PO)(2)center dot xC(7)H(8) (Ln = Dy, x = 0, Dy-B-Ph3PO; Ln = Yb, x = 1, Yb-B-Ph3PO) have been achieved by a one-pot reaction of Ln[N(TMS)(2)](3) (TMS = -SiMe3) with excess catecholborane (HBCat) in the presence of Ph3PO. Both macrocycles exhibit high brightness and long lifetimes benefitting from the combination of the rigid molecular backbone and the diminishing detrimental high energy X-H (X = C, N and O) vibrations. In particular, Dy-B-Ph3PO exhibited the longest F-4(9/2) lifetime beyond 200 mu s to date. When (4-(anthracen-9-yl)phenyl)diphenylphosphine oxide (AnPh(3)PO) was used as the antenna ligand, a highly luminescent NIR bioprobe, Yb-B-AnPh(3)PO, showing no apparent cell toxicity and high quality in vitro imaging, was obtained. Furthermore, the synthetic versatility of this system permits additional investigations of multifunctional Ln molecular materials in the future.

Automated summary

Boron-assisted synthesis of highly luminescent and long-lived lanthanide macrocycles has been achieved, which can serve as bioprobes with high-quality in vitro imaging and no apparent cell toxicity.