[Copper(phenanthroline)(bisisonitrile)]<sup>+</sup>-Complexes for the Visible-Light-Mediated Atom Transfer Radical Addition and Allylation Reactions

Knorn, Matthias; Rawner, Thomas; Czerwieniec, Rafał; Reiser, Oliver

doi:10.1021/acscatal.5b01071

Cited by 177 publications

(111 citation statements)

References 80 publications

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“…[4,9, Improvements were also stimulated in the fields of related functional materials based on metal complexes for sensing of oxygen or temperature [53][54][55][56][57][58][59] or for photocatalysis. [60][61][62][63][64][65][66] For luminescent materials to be applied in OLEDs, it is essential that all excitons generatedi nt he emission layer are harvesteda nd converted into photons. Since the statistic ratio of the formed excitons is one singlet to three triplets, [67,68] special mechanisms that allow to harvest all of them are required, as the two types of excitons show different relaxation properties.…”

Section: Introductionmentioning

confidence: 99%

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes

et al. 2017

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The development of organic light emitting diodes (OLEDs) and the use of emitting molecules have strongly stimulated scientific research of emitting compounds. In particular, for OLEDs it is required to harvest all singlet and triplet excitons that are generated in the emission layer. This can be achieved using the so-called triplet harvesting mechanism. However, the materials to be applied are based on high-cost rare metals and therefore, it has been proposed already more than one decade ago by our group to use the effect of thermally activated delayed fluorescence (TADF) to harvest all generated excitons in the lowest excited singlet state S . In this situation, the resulting emission is an S →S fluorescence, though a delayed one. Hence, this mechanism represents the singlet harvesting mechanism. Using this effect, high-cost and strong SOC-carrying rare metals are not required. This mechanism can very effectively be realized by use of Cu or Ag complexes and even by purely organic molecules. In this investigation, we focus on photoluminescence properties and on crucial requirements for designing Cu and Ag materials that exhibit short TADF decay times at high emission quantum yields. The decay times should be as short as possible to minimize non-radiative quenching and, in particular, chemical reactions that frequently occur in the excited state. Thus, a short TADF decay time can strongly increase the material's long-term stability. Here, we study crucial parameters and analyze their impact on the TADF decay time. For example, the energy separation ΔE(S -T ) between the lowest excited singlet state S and the triplet state T should be small. Accordingly, we present detailed photophysical properties of two case-study materials designed to exhibit a large ΔE(S -T ) value of 1000 cm (120 meV) and, for comparison, a small one of 370 cm (46 meV). From these studies-extended by investigations of many other Cu TADF compounds-we can conclude that just small ΔE(S -T ) is not a sufficient requirement for short TADF decay times. High allowedness of the transition from the emitting S state to the electronic ground state S , expressed by the radiative rate k (S →S ) or the oscillator strength f(S →S ), is also very important. However, mostly small ΔE(S -T ) is related to small k (S →S ). This relation results from an experimental investigation of a large number of Cu complexes and basic quantum mechanical considerations. As a consequence, a reduction of τ(TADF) to below a few μs might be problematic. However, new materials can be designed for which this disadvantage is not prevailing. A new TADF compound, Ag(dbp)(P -nCB) (with dbp=2,9-di-n-butyl-1,10-phenanthroline and P -nCB=bis-(diphenylphosphine)-nido-carborane) seems to represent such an example. Accordingly, this material shows TADF record properties, such as short TADF decay time at high emission quantum yield. These properties are based (i) on geometry optimizations of the Ag complex for a fast radiative S →S rate and (ii) on restricting the extent of geometry reorganiza...

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Section: Introductionmentioning

confidence: 99%

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes

et al. 2017

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“…[261] Neben homoleptischen Cu I -Komplexen sind auch heteroleptische Kupfer(I)-Komplexe leicht zugänglich, und es wurde gezeigt, dass Phenanthrolin/Bisisonitril-basierte Katalysatoren (Schema 72, rechts) [262] hinsichtlich Reduktionskraft und Lebensdauer des angeregten Zustandes überlegen sind (Cu I *( E 1/2 = À1.43 V für[Cu(dap) 2 ]Cl 258, t = 270 ns, E 1/2 = À1.88 Vfür[Cu(dpp)-(binc)]BF 4 259, t = 17 ns) (dpp = 2,9-Diphenyl-1,10-phenanthrolin, binc = Bis(2-isocyanophenyl)phenylphosphonat). [260,263] WiefürRu II oder Ir III diskutiert (Schema 82), kçnnten die Cu I -katalysierten, durch sichtbares Licht vermittelten ATRA-Prozesse sowohl einem Photoredoxzyklus als auch einem Radikalkettenmechanismus unterliegen. Darüber hinaus war es mçglich, Allylstannane und Allylsilane als Alken-Gegenstücke zu verwenden, wodurch Allylierungen von Alkylhalogeniden mçglich werden.…”

Section: [2+ +2]-cycloadditionenunclassified

“…Darüber hinaus war es mçglich, Allylstannane und Allylsilane als Alken-Gegenstücke zu verwenden, wodurch Allylierungen von Alkylhalogeniden mçglich werden. [260,263] WiefürRu II oder Ir III diskutiert (Schema 82), kçnnten die Cu I -katalysierten, durch sichtbares Licht vermittelten ATRA-Prozesse sowohl einem Photoredoxzyklus als auch einem Radikalkettenmechanismus unterliegen. Letzterer wurde fürd ie Kupfer(I)-katalysierten Azidierung von Toluolen vorgeschlagen.…”

Section: [2+ +2]-cycloadditionenunclassified

Photokatalyse mit sichtbarem Licht: Welche Bedeutung hat sie für die organische Synthese?

et al. 2018

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Die Photokatalyse mit sichtbarem Licht hat sich im letzten Jahrzehnt zu einer breit angewandten Methode in der organischen Synthese entwickelt. Für viele wichtige Reaktionen, wie Kreuzkupplungen, α‐Amino‐Funktionalisierungen, Cycloadditionen, ATRA‐Reaktionen oder Fluorierungen, wurden photokatalytische Varianten berichtet. Um Chemiker bei der Auswahl photokatalytischer Methoden für ihre Synthesen zu unterstützen, vergleichen wir in diesem Aufsatz klassische und photokatalytische Verfahren für ausgewählte Reaktionsklassen und zeigen deren Vorteile und Grenzen auf. In vielen Fällen verlaufen die photokatalytischen Reaktionen unter milderen Reaktionsbedingungen, typischerweise bei Raumtemperatur, und stöchiometrische Reagenzien werden durch einfache Oxidanzien oder Reduktionsmittel wie Luft, Sauerstoff oder Amine ersetzt. Beeinflusst die Photokatalyse mit sichtbarem Licht die organische Synthese? Die Aussicht, Elektronen zu Substraten und Zwischenprodukten hin‐ und herzuschieben oder Energie selektiv durch einen sichtbares Licht absorbierenden Photokatalysatoren zu übertragen, verspricht die aktuellen Verfahren in der Radikalchemie zu verbessern und neue Wege durch den Zugang zu reaktiven, bisher unbekannten Spezies zu erschließen, insbesondere durch das Zusammenspiel von Photokatalyse mit der Organo‐ oder Metallkatalyse.

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“…[22] Additionally,C uCl 2 undergoes irreversible chlorine-atom transfer with carbon-centered radicals;these features together made it asuitable candidate for this reaction. [23][24][25] We were pleased to find that the use of CuCl 2 in MeCN as ac hlorine-atom source afforded small amounts of the desired regioisomer,the yield of which could be improved to 62 %through the use of 2,2'-bipyridine (bpy) as as upporting ligand ( Table 1, entry 4).…”

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confidence: 99%

Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis

2017

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Halofunctionalization of alkenes is a classical method for olefin difunctionalization and give rise to adducts which are found in many natural products, biologically active molecules, and offer a synthetic handle for further manipulation. Classically, this reaction is performed with an electrophilic halogen source and gives rise to regioselective formation of the halofunctionalized adducts. In this work, we demonstrate a reversal of the native regioselectivity for alkene halofunctionalization reactions through the use of an acridinium photooxidant in conjunction with a copper cocatalyst.

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[Copper(phenanthroline)(bisisonitrile)]⁺-Complexes for the Visible-Light-Mediated Atom Transfer Radical Addition and Allylation Reactions

Cited by 177 publications

References 80 publications

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes

Photokatalyse mit sichtbarem Licht: Welche Bedeutung hat sie für die organische Synthese?

Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis

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[Copper(phenanthroline)(bisisonitrile)]+-Complexes for the Visible-Light-Mediated Atom Transfer Radical Addition and Allylation Reactions

Cited by 177 publications

References 80 publications

TADF Material Design: Photophysical Background and Case Studies Focusing on CuIand AgIComplexes

TADF Material Design: Photophysical Background and Case Studies Focusing on CuIand AgIComplexes

Photokatalyse mit sichtbarem Licht: Welche Bedeutung hat sie für die organische Synthese?

Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis

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[Copper(phenanthroline)(bisisonitrile)]⁺-Complexes for the Visible-Light-Mediated Atom Transfer Radical Addition and Allylation Reactions

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes

TADF Material Design: Photophysical Background and Case Studies Focusing on Cu^Iand Ag^IComplexes