<i>Nido</i>‐Carboranes: Donors for Thermally Activated Delayed Fluorescence

Nghĩa, Nguyễn Văn; Jana, Saibal; Sujith, S.; Ryu, Ji Yeon; Lee, Ji Min; Lee, Sang Uck; Lee, Min Hyung

doi:10.1002/ange.201806922

Cited by 26 publications

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“…Recently, organic TADF molecules that possess very small ΔE ST values have emerged as a new class of PSs. 25,71,72 Owing to the extremely small ΔE ST values, TADF molecules can efficiently undergo both intersystem crossing and reverse intersystem crossing processes under ambient conditions, leading to high triplet quantum yields and long-lived delayed fluorescence (∼μs). 27 Consequently, TADF molecules can work as potential photodynamic agents and in time-resolved luminescence imaging (TRLI) and biosensing.…”

Section: Heavy-atom-free Photosensitizers Based On Sulfur-substituted...mentioning

confidence: 99%

Heavy-Atom-Free Photosensitizers: From Molecular Design to Applications in the Photodynamic Therapy of Cancer

et al. 2020

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Section: Heavy-atom-free Photosensitizers Based On Sulfur-substituted...mentioning

confidence: 99%

Heavy-Atom-Free Photosensitizers: From Molecular Design to Applications in the Photodynamic Therapy of Cancer

et al. 2020

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“…Recent research has shown that the ICT-based luminescence characteristics of D‒A dyads are dramatically affected by the electronic environment of the o -carborane cage. For example, the photophysical properties are drastically altered by the deboronation of a closo - o -carborane to give a nido - o -carborane (nest-like structure, where one boron atom is removed from the icosahedron) [ 33 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ], as the anionic character of the nido -type structure interrupts the ICT transition [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. The intrinsic differences between the electronic properties of closo - and nido - o -carboranes have been investigated, providing inspiration as novel molecular scaffolds for chemodosimeter materials.…”

Section: Introductionmentioning

confidence: 99%

Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9H-carbazole-Based ortho-Carboranyl Luminophores

Lee

Mun

et al. 2021

Molecules

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The photophysical properties of closo-ortho-carboranyl-based donor–acceptor dyads are known to be affected by the electronic environment of the carborane cage but the influence of the electronic environment of the donor moiety remains unclear. Herein, four 9-phenyl-9H-carbazole-based closo-ortho-carboranyl compounds (1F, 2P, 3M, and 4T), in which an o-carborane cage was appended at the C3-position of a 9-phenyl-9H-carbazole moiety bearing various functional groups, were synthesized and fully characterized using multinuclear nuclear magnetic resonance spectroscopy and elemental analysis. Furthermore, the solid-state molecular structures of 1F and 4T were determined by X-ray diffraction crystallography. For all the compounds, the lowest-energy absorption band exhibited a tail extending to 350 nm, attributable to the spin-allowed π–π* transition of the 9-phenyl-9H-carbazole moiety and weak intramolecular charge transfer (ICT) between the o-carborane and the carbazole group. These compounds showed intense yellowish emission (λem = ~540 nm) in rigid states (in tetrahydrofuran (THF) at 77 K and in films), whereas considerably weak emission was observed in THF at 298 K. Theoretical calculations on the first excited states (S1) of the compounds suggested that the strong emission bands can be assigned to the ICT transition involving the o-carborane. Furthermore, photoluminescence experiments in THF‒water mixtures demonstrated that aggregation-induced emission was responsible for the emission in rigid states. Intriguingly, the quantum yields and radiative decay constants in the film state were gradually enhanced with the increasing electron-donating ability of the substituent on the 9-phenyl group (‒F for 1F < ‒H for 2P < ‒CH3 for 3M < ‒C(CH3)3 for 4T). These features indicate that the ICT-based radiative decay process in rigid states is affected by the electronic environment of the 9-phenyl-9H-carbazole group. Consequently, the efficient ICT-based radiative decay of o-carboranyl compounds can be achieved by appending the o-carborane cage with electron-rich aromatic systems.

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Aggregation‐Induced Electrochemiluminescence of Carboranyl Carbazoles in Aqueous Media

et al. 2019

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The aggregation‐induced electrochemiluminescence (AIECL) of carboranyl carbazoles in aqueous media was investigated for the first time. Quantum yields, morphologies, and particle sizes were observed to determine the electrochemiluminescence (ECL) performance of these aggregated organic dots (ODs). All compounds exhibit much higher ECL stability and intensity than the carborane‐free compound, demonstrating the essential role of the carboranyl motif. Moreover, the results of cyclic voltammetry (CV) suggest that oxidation/reduction reactions take place at the carboranyl motif. The excited states of ODs were proposed to be generated by the mechanism of surface state transitions. More importantly, these compounds show a reductive–oxidative mechanism in contrast to other organic materials that show oxidative–reductive mechanisms. Our experiments and data have established the relation between AIE organic structures and ECL properties that has a strong potential for biological and diagnostic applications.

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Nido‐Carboranes: Donors for Thermally Activated Delayed Fluorescence

Abstract: Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Cited by 26 publications

References 67 publications

Heavy-Atom-Free Photosensitizers: From Molecular Design to Applications in the Photodynamic Therapy of Cancer

Heavy-Atom-Free Photosensitizers: From Molecular Design to Applications in the Photodynamic Therapy of Cancer

Influence of Electronic Environment on the Radiative Efficiency of 9-Phenyl-9H-carbazole-Based ortho-Carboranyl Luminophores

Aggregation‐Induced Electrochemiluminescence of Carboranyl Carbazoles in Aqueous Media

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