TY  - JOUR
A1  - Wu, Zhu
A1  - Dinkelbach, Fabian
A1  - Kerner, Florian
A1  - Friedrich, Alexandra
A1  - Ji, Lei
A1  - Stepanenko, Vladimir
A1  - Würthner, Frank
A1  - Marian, Christel M.
A1  - Marder, Todd B.
T1  - Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature
JF  - Chemistry—A European Journal
N2  - Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T\(^M_1\) state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T\(^A_1\) state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.
KW  - AIE
KW  - luminescence
KW  - phosphorescence
KW  - triarylborane
KW  - triplet
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318297
VL  - 28
IS  - 30
ER  - 
TY  - JOUR
A1  - Wu, Zhu
A1  - Roldao, Juan Carlos
A1  - Rauch, Florian
A1  - Friedrich, Alexandra
A1  - Ferger, Matthias
A1  - Würthner, Frank
A1  - Gierschner, Johannes
A1  - Marder, Todd B.
T1  - Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP)
JF  - Angewandte Chemie
N2  - Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)\(_{3}\) does not luminesce in the solid state when irradiated at 250–400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.
KW  - boric acid
KW  - room-temperature phosphorescence (RTP)
KW  - optical materials
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318308
VL  - 61
IS  - 15
ER  -