Boron‐Doped Tri(9,10‐anthrylene)s: Synthesis, Structural Characterization, and Optoelectronic Properties

Abstract

The reaction of 9,10-dibromo-9,10-dihydro-9,10-diboraanthracene (9,10-dibromo-DBA, 3) with two equivalents of 9-lithio-2,6- or 9-lithio-2,7-di-tert-butylanthracene gave the corresponding 9,10-dianthryl-DBAs featuring two (4) or four (5) inward-pointing tert-butyl groups. Compound 4 exists as two atropisomers, 4 and 4', due to hindered rotation about the exocyclic B-C bonds. X-ray crystallography of 5 suggests that the overall interactions between facing tert-butyl groups are attractive rather than repulsive. Even in solution, 4/4' and 5 are stable toward air and moisture for several hours. Treatment of 3 with 10-lithio-9-R-2,7-di-tert-butylanthracenes carrying phenyl (R=Ph), dimesitylboryl (R=Mes(2)B), or N,N-di(p-tolyl)amino (R=Tol(2)N) groups gave the corresponding 9,10-dianthryl-DBA derivatives 9-11 in moderate to good yields. In these molecules, all four solubilizing tert-butyl groups are outward pointing. The solid-state structures of 4, 5, 9, and 10 reveal twisted conformations about the exocyclic B-C bonds with dihedral angles of 70-90°. A significant electron-withdrawing character was proven for the Mes(2)B moiety, but no appreciable +M effect was evident for Tol(2)N. Compounds 5, 9, and 11 show two reversible DBA-centered reduction waves in the cyclic voltammogram. In the case of 10, a third reversible redox transition can be assigned to the Mes(2)B-anthryl substituents. The UV/Vis absorption spectrum of 5 is characterized by a very broad band at λ(max)=510 nm, attributable to a twisted intramolecular charge-transfer interaction from the anthryl donors to the DBA acceptor. The corresponding emission band shows pronounced positive solvatochromism (λ(em)=567 nm, C(6)H(12); 680 nm, CH(2)Cl(2)) in line with a highly polar excited state. The charge-transfer bands of 10 and 11, as well as the emission bands of 9 and 10, are redshifted relative to those of 5. The Tol(2)N derivative 11 is essentially nonfluorescent in solution, but emits bright wine-red light in the solid state.

Synthesis of Silicon‐Functionalized Dibenzosilaborins by Intramolecular BH/CH Dehydrogenative Cyclization and Their Tunable Photophysical and Chemical Properties by Silyl Groups

“…The absorption can be attributed to twisted intramolecular charge transfer (TICT) from the electron‐rich mesityl group to the electron‐poor dibenzosilaborin unit 2f. h…”

How Boron Doping Shapes the Optoelectronic Properties of Canonical and Phenylene‐Containing Oligoacenes: A Combined Experimental and Theoretical Investigation

“…The parent compound (R=R′=H) can readily be derivatized through hydroboration reactions to furnish brightly luminescent, yet air‐ and moisture‐sensitive products . 9,10‐Dimesityl‐9,10‐dihydro‐9,10‐diboraanthracene ( DBA ; Figure ) is long‐term stable, even under ambient conditions; a similarly stabilizing effect can be achieved through the introduction of 9‐anthryl substituents at the boron centers or by applying the concept of structural constraint . As a downside of these approaches, functionalization is now largely restricted to variations of the phenylene substituents R′.…”

Push–pull type porphyrin based sensitizers: The effect of donor structure on the light-harvesting ability and photovoltaic performance

“…The dyes WW-7 and WW-8 are green solid and soluble in normal solvents such as dichloromethane (DCM), chloroform and tetrahydrofuran (THF). They were thoroughly characterized by 1 H NMR, 13 C NMR, and high resolution mass spectrometry (HR MS) (ESI †).…”

“…The reference porphyrin dye 21 and the intermediate compounds 1 [11], 4 [4] and 5 [12] were synthesized as previously reported. Compound 2 was synthesized in 98% yield by bromination of 1 with N-bromosuccinimide (NBS) catalyzed by FeCl 3 [13]. Sonogashira coupling of 2 with trimethylsilylacetylene followed…”