Circular dichroism in excited triplet states. 2. Chiral dimer-like molecules in the binaphthyl and spirobifluorene series

Tétreau, Catherine; Lavalette, Daniel; Cabaret, D.; Geraghty, Niall W. A.; Welvart, Z.

doi:10.1021/j100240a014

Cited by 14 publications

(13 citation statements)

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“…As its precursor 1,1 0 -binaphthol, 1 has an axial chirality due to the fact that the molecule is not planar. This molecule assembles the following advantages: (i) compared to its precursor, bridging the hydroxy of 1,1 0 -binaphthol forces the molecule in a helical conformation resulting in a dramatic increase of the molecular optical rotation from 45 ml dm À1 g À1 for 1,1 0 -binaphthol to 800 ml dm À1 g À1 for 1, 18 (ii) it is easily accessible in one step and in an enantiopure form from commercial R-(+)-1,1 0 -binaphthol or S-(À)-1, 1 0 -binaphthol, 16 and (iii) bridging the hydroxy also results in an increase of the molecule stability toward the racemisation that may occur for 1,1 0 -binaphthol by rotation around the binaphthyl bond. 19 Thin films were made in a vacuum chamber by focusing a laser beam from a KrF laser (l ¼ 248 nm) on a polycrystalline powder target of 1 and collecting the evaporated species on a glass substrate.…”

Section: Resultsmentioning

confidence: 99%

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Pure chiral organic thin films with high isotropic optical activity synthesized by UV pulsed laser deposition

Guy

Bensalah‐Ledoux

et al. 2009

J. Mater. Chem.

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Section: Resultsmentioning

confidence: 99%

“…an inversion of the molecule's dihedral angle by a thermal and/or photochemical process. 19,22 For the high fluence regime, namely higher than 32 mJ cm À2 (zone III in Fig. 4), degradation occurs leading to a dramatic decrease of the OA and to a yellowish coloration of the films.…”

Section: Resultsmentioning

confidence: 99%

Pure chiral organic thin films with high isotropic optical activity synthesized by UV pulsed laser deposition

Guy

Bensalah‐Ledoux

et al. 2009

J. Mater. Chem.

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“…The success story of the spiro-type optoelectronic materials should be started from the SBF fragment, which was first synthesized by Clarkson and Gomberg in 1930 . The early research of SBF was mainly around the synthesis of chiral molecules functionalized from the unsymmetrical C2, C2′ sites on the two fluorene segments . Now, the SBF platform offers various design options for the prosperous organic optoelectronic study. − In 2007, Salbeck et al had demonstrated a comprehensive overview of the basic physicochemical properties of spiro compounds and their applications in thin-film devices .…”

Section: The Functionalization Of the Spiro Compoundsmentioning

confidence: 99%

Spiro Compounds for Organic Light-Emitting Diodes

Zheng

Fan

et al. 2021

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS:The development of cutting-edge optoelectronic devices is rapidly changing science and technology. The organic light-emitting diodes (OLEDs), as one of the most applicable techniques of organic electronics, are experiencing the process of materials' upgrade. Among all the organic units to construct OLED materials, the spiro structure and its derived compounds have been widely studied due to the good thermal stability and unique orthogonally rigid structure. It had shown great potential in first generation fluorescent OLEDs (FOLEDs) and second generation phosphorescent OLEDs (PhOLEDs). Recently, it has achieved outstanding performance in third generation thermally activated delayed fluorescence (TADF) OLEDs, which is attributed to its orthogonal structure caused by the spiro atom; thus the spiro compound can innately separate the hole and electron which is beneficial for minimizing the singlet−triplet splitting energy (ΔE ST ). The most classic aromatic spiro unit is 9,9′-spriobifluorene (SBF), which was first reported in 1930. The study of aromatic spiro compounds is closely related to the development of organic semiconductors; now, the structure−property relationship of spiro compounds is getting clearer and attracting wide attention from the material community.In this Account, we briefly summarize the efforts on the functionalization and application of spiro compounds in OLEDs. The functionalization of spiro compounds in our group mainly focuses on the development of electron-rich spiro backbone and the adjustment of different substitution positions. In this regard, we have systematically studied the electron-rich spiro backbones which could greatly facilitate the carrier injection/transport and the new derivation positions (C1, C3, and C4 at fluorene moiety) can markedly affect the energy levels of triplet excitons, which is crucial for host materials in OLEDs, especially for the blue ones. The two main methods, i.e., backbone modification and position engineering, can cooperate to construct a rigid scaffold to realize spatial donor/acceptor intramolecular interaction, which confines the donor/acceptor distance. Afterward, the application of spiro compounds in OLEDs is elucidated from FOLEDs to PhOLEDs, then to TADF OLEDs. The spiro[acridine-9,9′-fluorene] (SAF) unit is our first example to enhance the performance of blue and violet fluorescent emitters, which have reached the theoretical upper limit of FOLEDs. For PhOLEDs, the spiro-type compounds are mainly used as host materials. The substitution positions of the SBF unit are thus thoroughly investigated to afford host materials with high triplet energy. And the SAF unit is modified to form ambipolar host materials to balance hole/electron injection for better white PhOLEDs. During this research, we understood the importance of the orthogonal arrangement in the spiro structure for ambipolar material design. Finally, TADF materials based on the spiro compounds are also presented. The spiro materials used in TA...

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“…Ru(bvy)~ +. While CD spectra of some very long-lived excited states of chiral organic molecules had previously been measured with modifications of standard methods for obtaining CD spectra [32][33][34], the use of the TRCD technique to measure the CD spectrum of the luminescent state of Ru(bpy)~ + was the first example of a true time-resolved measurement of a CD spectrum of a molecular excited state [16].…”

Section: B Studies Of Transition Metal Complexesmentioning

confidence: 99%