Control of the Emission Behaviors of Trifunctional o‐Carborane Dyes

Abstract

A series of organic dyes were synthesized that contain an o‐carborane unit in combination with phenanthrene, tolane, and BODIPY moieties. In solution, compound 7 a, which has phenanthrene and tolane units, does not emit as a result of an intramolecular charge transfer (ICT) from the emitters to the C1C2 bond of the o‐carborane cage, whereas, in the aggregate and solid state, 7 a emits intense green light through aggregation‐induced emission (AIE). In solution, compound 7 b, which has phenanthrene, tolane, and BODIPY units, emits green light from the BODIPY moiety, whereas, in both the aggregate and solid state, it does not emit as a result of the energy transfer from the phenanthrene and tolanes to the neighboring BODIPY units and the successive aggregation‐caused quenching (ACQ) mechanism. This work shows that the emission behaviors, the ICT, AIE, energy transfer, and ACQ, of these dyes can be controlled by the substituents at the o‐carborane core.

Highly Deformedo‐Carborane Functionalised Non‐linear Polycyclic Aromatics with Exceptionally Long C−C Bonds

“…Whenever molecular motion is restricted, however, carboranyl ICT states become more radiative. This often occurs upon aggregation, in a process known as aggregation induced emission (AIE) [7, 17, 18, 20–39] . o ‐Carborane is therefore considered an ‘AIE‐active element block’ [40]…”

“…This often occurs upon aggregation,i naprocess knowna sa ggregationi nduced emission (AIE). [7,17,18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] o-Carborane is therefore considered an 'AIE-active element block'. [40] The AIE efficiency in carborane-containing fluorophores is enhanced when the rotation of the carboranei ss tructurally restricted around the ICT geometry (i.e.,w hen the C C ÀC C bond is approximately perpendicular to plane of the fluorophore).…”

Single-Electron Oxidation/Alterable C3- and C10-Arylation of 9-MeO-phenanthrene

“…With these functional groups, together with −OMe and −NMe 2 , which were readily demethylated as −OH and −NH 2 groups, product 5 could serve as an important building block for the design and synthesis of functional materials such as antioxidants, 43 PEEKs, 44 poly aryl esters, 45 and optoelectronic materials. 46,47 In the final step, a mechanistic investigation was performed to clarify the unique regioselectivity of 1 in its C3-arylation process, as well as the alterable regioselectivity in C10-site. Based on the oxidation potentials of 1 and 3a, both of the two substrates could undergo single-electron oxidation in the presence of S 2 O 8 2− under neutral conditions, giving the corresponding radical cations 1 +• and 3a +• .…”

“…In these entries, the reaction was proved tolerant to a series of substituents, including phenyl, tolyl, biphenyl, chloro, methoxyl, fluoro, and bromo groups. With these functional groups, together with −OMe and −NMe 2 , which were readily demethylated as −OH and −NH 2 groups, product 5 could serve as an important building block for the design and synthesis of functional materials such as antioxidants, PEEKs, poly aryl esters, and optoelectronic materials. , …”

Effects of Multi‐Carborane Substitution on the Photophysical and Electron‐Accepting Properties of o‐Carboranylbenzene Compounds

“…To date, to induce fascinating photophysical properties, structural modifications have been made through the incorporation of o ‐carborane groups into transition‐metal complexes or organic luminophores . In particular, o ‐carborane‐incorporated organic luminophores often exhibit unusual multiple‐emission behavior, derived from discrete intramolecular charge‐transfer (ICT) and locally excited (LE) states . These features have been mainly observed in the donor–acceptor dyad systems in which the o ‐carborane group acts as an acceptor.…”