Carborane‐Induced Excimer Emission of Severely Twisted Bis‐o‐Carboranyl Chrysene

Abstract

The synthesis of a highly twisted chrysene derivative incorporating two electron deficient o‐carboranyl groups is reported. The molecule exhibits a complex, excitation‐dependent photoluminescence, including aggregation‐induced emission (AIE) with good quantum efficiency and an exceptionally long singlet excited state lifetime. Through a combination of detailed optical studies and theoretical calculations, the excited state species are identified, including an unusual excimer induced by the presence of o‐carborane. This is the first time that o‐carborane has been shown to induce excimer formation ab initio, as well as the first observation of excimer emission by a chrysene‐based small molecule in solution. Bis‐o‐carboranyl chrysene is thus an initial member of a new family of o‐carboranyl phenacenes exhibiting a novel architecture for highly‐efficient multi‐luminescent fluorophores.

Solid‐State Photochromism by Molecular Assembly of Bis‐o‐carboranyl Siloles

“…It is well known that the optimum intermolecular distance for the excitonic coupling is about3-4 for many organic molecules. [58][59][60] However,r egarding Si-m-Cb,t he observed distances betweent wo neighboring units are 10.66 (for face-to-face interactions) and 13.88 (for head-to-tail interaction;s ee Figure S10 in the Supporting Information). As the dipole-dipolee xcitonici nteraction energy is inverselyp roportional to r 3 ,w here r denotes the distance between two transition dipoles, these values are too large to lead to redshifted emission by strong excitonic splitting.…”

Atomically Defined Monocarborane Copper(I) Acetylides with Structural and Luminescence Properties Tuned by Ligand Sterics

“…For 3 and 5,t he CCu nit is s-bonding to one [Cu(PR 3 ) 2 ] + fragment and side-on interacting with the second [CuPR 3 ] + fragment (5 displayed in Figure 2a). a) Solid-state structure of the anionic fragmento f2 (hydrogen atoms omitted for clarity;30% displacement ellipsoids); b) Cu 14 14 + core of 2 (Cu I ÀCu I interactions lie in the range of 2.4411(8)-2.8010 (7) ). Figure 1.…”

“…The solid state structure comprised a multinuclear [(C) 8 Cu 14 (NH 3 ) 4 (acetone) 4 ] 2À fragment and two [Cu(acetone) 2 ] + cations for chargec ompensation. The anionic moiety contains aC u 14 14 + core of distorted square antiprismatic geometry surrounded by eight dianionic carboranea cetylide ligands( Figure 1). Additional NH 3 and acetone ligandsc omplete the coordination sphere of eight of the Cu I centers.…”

“…Figure 1. a) Solid-state structure of the anionic fragmento f2 (hydrogen atoms omitted for clarity;30% displacement ellipsoids); b) Cu 14 14 + core of 2 (Cu I ÀCu I interactions lie in the range of 2.4411(8)-2.8010 (7) ).…”

Time‐Dependent Emission Enhancement of the Ethynylpyrene‐o‐Carborane Dyad and Its Application as a Luminescent Color Sensor for Evaluating Water Contents in Organic Solvents

“…[14][15][16][17][18][19][20][21][22][23] Furthermore, based on the solid-state emission enhanced by the ocarborane unit, variable luminescentp roperties such as aggre-gation-induced emission enhancement (AIEE) were also demonstrated from the aryl-modified o-carborane derivatives. [24][25][26][27][28][29][30][31][32][33][34][35] In the absence of structural restriction such in the solution state, intramolecular motions and subsequently excitationd eactivation critically occurred, leadingt oa nnihilation of the ICT emission. [36] By suppressing thesem otions, the deactivation process was restricted, and consequently intense emission was recovered.…”