Making triplets from photo-generated charges: observations, mechanisms and theory

Gibbons, Dáire; Farawar, Aram; Mazzella, Paul; Leroy‐Lhez, Stéphanie; Williams, René M.

doi:10.1039/c9pp00399a

Cited by 98 publications

(134 citation statements)

References 73 publications

(92 reference statements)

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“…Triplet‐state formation quantum yields of SF1 – 3 were determined to be relatively high in cyclohexane (Table 1) and comparable to those reported for good triplet sensitizers [6, 26, 30, 38, 39] . The triplet quantum yield of SF2 decreased from 67 % to 43 % in 2‐MeTHF and decreased further to 16 % in DMSO.…”

Section: Resultssupporting

confidence: 78%

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Sandoval‐Salinas

et al. 2020

Angew Chem Int Ed

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Spiro conjugation has been proposed to dictate the efficiency of charge transfer,w hich could directly affect the spin-orbit charge transfer intersystem crossing (SOCT-ISC) process.H owever,t his process has yet to be exemplified. Herein, we prepared three spirobis[anthracene]diones,i n which two benzophenone moieties are locked in close proximity and differentially functionalized to fine-tune the charge transfer state.I ts feasibility for SOCT-ISC was theoretically predicted, then experimentally evaluated. Through fine-tuning the spiro conjugation coupling and varying the solvent dielectric constants,ISC rate constants were engineered to vary in ad ynamic range of three orders of magnitude,f rom 7.8 10 8 s À1 to 1.0 10 11 s À1 ,w hich is the highest ISC rate reported for SOCT-ISC system to our knowledge.O ur findings substantiate the key factors for effective SOCT-ISC and offer anew avenue for the rational design of heavy atom free triplet sensitizers.

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Section: Resultssupporting

confidence: 78%

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Sandoval‐Salinas

et al. 2020

Angew Chem Int Ed

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“…[18] Another design strategy consists in coupling the carbazole electron-donating (D) group to an electron-accepting (A) group into at wisted (D-A) system to favor at wisted intramolecular charge-transfer (TICT), [19,20] one of the ways to generate triplet states via charge transfer states. [21] Indeed, such atwisted structure is well known in the field of molecules exhibiting thermally activated delayed fluorescence (TADF) for promoting as patial separation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), that leads to as mall DE ST and an increase of the ISC rate. [22] Ultimately,b yc ontrolling the intramolecular energy transfer between triplet excited states of the Dand Agroups and introducing aheavy atom such as bromine,t he twisted phosphors approach allows to reach phosphorescence quantum yield and lifetime up to 41 %a nd 0.54 s, respectively.…”

Section: Introductionmentioning

confidence: 99%

σ‐Conjugation and H‐Bond‐Directed Supramolecular Self‐Assembly: Key Features for Efficient Long‐Lived Room Temperature Phosphorescent Organic Molecular Crystals

Demangeat

Dou

et al. 2020

Angew Chem Int Ed

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Long‐lived room temperature phosphorescence from organic molecular crystals attracts great attention. Persistent luminescence depends on the electronic properties of the molecular components, mainly π‐conjugated donor–acceptor (D‐A) chromophores, and their molecular packing. Here, a strategy is developed by designing two isomeric molecular phosphors incorporating and combining a bridge for σ‐conjugation between the D and A units and a structure‐directing unit for H‐bond‐directed supramolecular self‐assembly. Calculations highlight the critical role played by the two degrees of freedom of the σ‐conjugated bridge on the chromophore optical properties. The molecular crystals exhibit RTP quantum yields up to 20 % and lifetimes up to 520 ms. The crystal structures of the efficient phosphorescent materials establish the existence of an unprecedented well‐organization of the emitters into 2D rectangular columnar‐like supramolecular structure stabilized by intermolecular H‐bonding.

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“…Tr iplet-state formation quantum yields of SF1-3 were determined to be relatively high in cyclohexane (Table 1) and comparable to those reported for good triplet sensitizers. [6,26,30,38,39] Thet riplet quantum yield of SF2 decreased from 67 %to43%in 2-MeTHF and decreased further to 16 % in DMSO.T he same trend is seen in SF3.…”

Section: Angewandte Chemiementioning

confidence: 57%

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Sandoval‐Salinas

et al. 2020

Angewandte Chemie

View full text Add to dashboard Cite

Spiro conjugation has been proposed to dictate the efficiency of charge transfer,w hich could directly affect the spin-orbit charge transfer intersystem crossing (SOCT-ISC) process.H owever,t his process has yet to be exemplified. Herein, we prepared three spirobis[anthracene]diones,i nw hich two benzophenone moieties are locked in close proximity and differentially functionalizedt of ine-tune the charge transfer state.I ts feasibility for SOCT-ISC was theoretically predicted, then experimentally evaluated. Through fine-tuning the spiro conjugation coupling and varying the solvent dielectric constants,ISC rate constants were engineered to vary in adynamic range of three orders of magnitude,f rom 7.8 10 8 s À1 to 1.0 10 11 s À1 ,w hichi st he highest ISC rate reported for SOCT-ISC system to our knowledge.O ur findings substantiate the key factors for effective SOCT-ISC and offer anew avenue for the rational design of heavy atom free triplet sensitizers.

show abstract

Making triplets from photo-generated charges: observations, mechanisms and theory

Abstract: Photo-excitation of electron donor–acceptor systems can lead to the generation of a charge separated state (CT). Sometimes the charge recombination occurs mainly to the local triplet excited state (T1). How does the spin flip?

Cited by 98 publications

References 73 publications

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

σ‐Conjugation and H‐Bond‐Directed Supramolecular Self‐Assembly: Key Features for Efficient Long‐Lived Room Temperature Phosphorescent Organic Molecular Crystals

Engineering the Charge‐Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

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