Diversifying the luminescence of phenanthro-diimine ligands in zinc complexes

Temerova, Diana; Kisel, Kristina S.; Eskelinen, Toni; Melnikov, Andrei G.; Kinnunen, Niko M.; Hirva, Pipsa; Shakirova, Julia R.; Tunik, Sergey P.; Grachova, Elena V.; Koshevoy, Igor O.

doi:10.1039/d1qi00149c

Cited by 18 publications

(18 citation statements)

References 76 publications

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“…It is known that the presence of various chromophores at the coordination centre can lead to secondary interactions between chromophores π system and produce aggregates with dynamic optical properties and interligand charge-transfer processes. 44 We also observed different behaviors of our compounds in dependence on the type of anion coordinated to the metal centre and also on the groups connected to the salicylaldehyde rings.…”

Section: Resultsmentioning

confidence: 66%

New dinuclear zinc(ii) complexes with Schiff bases obtained from o-phenylenediamine and their application as fluorescent materials in spin coating deposition

et al. 2021

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Section: Resultsmentioning

confidence: 66%

New dinuclear zinc(ii) complexes with Schiff bases obtained from o-phenylenediamine and their application as fluorescent materials in spin coating deposition

et al. 2021

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“…One of the most recent fundamental developments concerning photoactive Zn II compounds pursues the idea to introduce other emission types than ligand-based fluorescence, for example, states with triplet and/or charge-transfer character in halide complexes. − To date, this specific research thrust seems to concentrate largely on the solid state, presumably because phosphorescence and charge-transfer emission are trickier to obtain in fluid solution at room temperature. The solution phase is however very relevant for photoactive triplet and charge-transfer excited states, due to possible applications in triplet energy-transfer catalysis, triplet–triplet annihilation upconversion, photoinduced electron transfer, and photoredox catalysis, including perspectives for solar energy conversion .…”

Section: Introductionmentioning

confidence: 99%

Zinc(II) Complexes with Triplet Charge-Transfer Excited States Enabling Energy-Transfer Catalysis, Photoinduced Electron Transfer, and Upconversion

Kübler

Pfund

Wenger

2022

JACS Au

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Many CuI complexes have luminescent triplet charge-transfer excited states with diverse applications in photophysics and photochemistry, but for isoelectronic ZnII compounds, this behavior is much less common, and they typically only show ligand-based fluorescence from singlet π–π* states. We report two closely related tetrahedral ZnII compounds, in which intersystem crossing occurs with appreciable quantum yields and leads to the population of triplet excited states with intraligand charge-transfer (ILCT) character. In addition to showing fluorescence from their initially excited 1ILCT states, these new compounds therefore undergo triplet–triplet energy transfer (TTET) from their 3ILCT states and consequently can act as sensitizers for photo-isomerization reactions and triplet–triplet annihilation upconversion from the blue to the ultraviolet spectral range. The photoactive 3ILCT state furthermore facilitates photoinduced electron transfer. Collectively, our findings demonstrate that mononuclear ZnII compounds with photophysical and photochemical properties reminiscent of well-known CuI complexes are accessible with suitable ligands and that they are potentially amenable to many different applications. Our insights seem relevant in the greater context of obtaining photoactive compounds based on abundant transition metals, complementing well-known precious-metal-based luminophores and photosensitizers.

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“…Interestingly, despite the d 10 electron configuration of Zn II and its high abundance (~75 ppm in the Earth's crust), only few triplet emitters have been developed so far, but a large number of purely fluorescent Zn II complexes is known. [18][19][20][21][22][23][24][25][26][27][28] This may be due to the fact that MLCT states cannot be formed due to the much higher ionization energy of Zn II compared to Cu I , which precludes the metal d-orbitals to be involved in the excited states and mediate SOC. Thus, predominantly intra-ligand CT (ILCT) or LC states have been studied for phosphorescence or TADF.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐Long Lived Luminescent Triplet Excited States in Cyclic (Alkyl)(amino)carbene Complexes of Zn(II) Halides

Mrózek

Gernert

Belyaev

et al. 2022

Chemistry A European J

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The high element abundance and d10 electron configuration make ZnII‐based compounds attractive candidates for the development of novel photoactive molecules. Although a large library of purely fluorescent compounds exists, emission involving triplet excited states is a rare phenomenon for zinc complexes. We have investigated the photophysical and ‐chemical properties of a series of dimeric and monomeric ZnII halide complexes bearing a cyclic (alkyl)(amino)carbene (cAAC) as chromophore unit. Specifically, [(cAAC)XZn(μ‐X)2ZnX(cAAC)] (X=Cl (1), Br (2), I (3)) and [ZnX2(cAAC)(NCMe)] (X=Br (4), I (5)) were isolated and fully characterized, showing intense visible light photoluminescence under UV irradiation at 297 K and fast photo‐induced transformation. At 77 K, the compounds exhibit improved stability allowing to record ultra‐long lifetimes in the millisecond regime. DFT/MRCI calculations confirm that the emission stems from 3XCT/LEcAAC states and indicate the phototransformation to be related to asymmetric distortion of the complexes by cAAC ligand rotation. This study enhances our understanding of the excited state properties for future development and application of new classes of ZnII phosphorescent complexes.

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Diversifying the luminescence of phenanthro-diimine ligands in zinc complexes

Abstract: Strongly blue fluorescent 1-phenyl-2-(pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole (L1) is a facile block for the construction of multichromophore organic molecules, and simultaneously serves as a chelating diimine ligand.

Cited by 18 publications

References 76 publications

New dinuclear zinc(ii) complexes with Schiff bases obtained from o-phenylenediamine and their application as fluorescent materials in spin coating deposition

New dinuclear zinc(ii) complexes with Schiff bases obtained from o-phenylenediamine and their application as fluorescent materials in spin coating deposition

Zinc(II) Complexes with Triplet Charge-Transfer Excited States Enabling Energy-Transfer Catalysis, Photoinduced Electron Transfer, and Upconversion

Ultra‐Long Lived Luminescent Triplet Excited States in Cyclic (Alkyl)(amino)carbene Complexes of Zn(II) Halides

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