Influence of the Bridging Elements on the Optical Properties of Linked 9,10-Dihydro-9,10-diboraanthracenes

Abstract

Starting from the monofunctionalized 9,10-dihydro-9,10-diboraanthracene derivatives MesB(C 6 H 4 ) 2 BX (X = H, Br), the bridged systems MesB(C 6 H 4 ) 2 B–L–B(C 6 H 4 ) 2 BMes have been synthesized with L = −C(H)═C(H)( p -C 6 Me 4 )C(H)═C(H)– ( 5 ), −C≡C( p -C 6 Me 4 )C≡C– ( 6 ), and −( p -C 6 H 4 )( p -C 6 Me 4 )( p -C 6 H 4 )– ( 7 ). The compounds were characterized by NMR, IR, UV/vis, and fluorescence spectroscopy. The vinyl- and phenylboranes 5 and 7 are pale yellow solids, whereas the alkynylborane 6 possesses a bright yellow color. The emission maxima of 5 – 7 in toluene are λ max (em) 477, 460, and 461 nm with quantum yields ϕ f of 0.02, 0.30, and 0.04, respectively. Alkynylborane 6 was found to be the least air- and moisture-sensitive of the three derivatives.