The dinuclear Ag(I) complex has been designed to show thermally activated delayed fluorescence (TADF) of high efficiency. Strongly electron-donating terminal ligands are introduced to destabilize the d orbitals of the Ag ions. Consequently, the orbitals distinctly contribute to the HOMO, whereas the LUMO is localized on the bridging ligand. This ensures charge transfer character of the lowest excited singlet S and triplet T states. Accordingly, a small energy gap ΔE(S-T) is obtained, being essential for TADF behavior. Photophysical investigations show that at ambient temperature the complex exhibits TADF reaching a quantum yield of Φ = 70% with the decay time of only τ = 1.9 μs, manifesting one of the fastest TADF decays observed so far. Such an outstanding TADF efficiency is based on a small value of ΔE(S-T) = 480 cm combined with a large transition rate of k(S → S) = 2.2 × 10 s.
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http://dx.doi.org/10.1021/acs.jpclett.7b03160 | DOI Listing |
Chemistry
December 2024
Department of Chemistry, Central University of Punjab, Bathinda, 151401, India.
The heterometallic [Ag(I)/Fe(II)] molecular electrocatalysts for hydrogen production were introduced here to recognize the mutual role of metallic nuclearity and ligand engineering. A series of ferrocenyl dithiophosphonate stabilized mononuclear [Ag(PPh){SPFc(OR)}] {where R=Me (1), Et (2), Pr (3), Pr (4), Amyl (5); Fc=Fe (ɳ-CH) (ɳ-CH)} and dinuclear [Ag(PPh){SPFc(OR}] {where R=Et (2 a), and Pr (3 a)} complexes were synthesized and characterized by SCXRD, NMR (P and H), ESI-MS, UV-Vis, and FT-IR spectroscopy. The comparative electrocatalytic HER behavior of 1-5 and 2 a-3 a showed effective current density of 1 mA/cm with overpotentials ranging from 772 to 991 mV, demonstrating the influence of extended and branched carbon chains in dithiophosphonates and metallic (mono-/di-) nuclearity, which correlates with documented tetra-nuclear [Ag(SPFc(OPr)], 6.
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July 2024
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, Zurich, 8057, Switzerland.
The coordination of anionic donors is involved at various stages of catalytic cycles in transition-metal catalysis, but control over the spatial positioning of anions around a metal center is a challenge in coordination chemistry. Here we show that regioisomeric phosphine-carboxylate ligands provide spatial anion control on palladium(II) centers by favoring either κ, cis-κ, or trans-κ coordination of the carboxylate donor. Additionally, the palladium(II) carboxylates, which contain a methyl donor, upon protonation, deliver metal-alkyl complexes that feature a coordinated carboxylic acid.
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May 2024
Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
We have utilised the 4,6-di--butyl resorcinol bis(diphenylphosphinite) (POCOP) ligand for exploring its coordination ability towards group 11 metal centres. The treatment of the bidentate ligand 1 with various coinage metal precursors afforded a wide range of structurally diverse complexes 2-12, depending upon the metal precursors used. This furnishes several multinuclear Cu(I) complexes with dimeric (2) and tetrameric cores (3, 4, and 5).
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September 2022
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Str. 16/10, 117997 Moscow, Russia.
A benzothiazole-substituted derivative (X) of 1,3-diaza-2-oxophenoxazine was evaluated with respect to its ability to engage in Ag(I)-mediated homo base pair formation in two different DNA duplexes. The metal binding was determined by a combination of temperature-dependent UV spectroscopy, CD spectroscopy, and fluorescence spectroscopy, indicating the incorporation of two Ag(I) ions to generate a dinuclear X-Ag(I)-X base pair. Interestingly, a luminescence increase was observed upon metal binding.
View Article and Find Full Text PDFMaterials (Basel)
March 2022
Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Torun, Poland.
Two Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)benzene () and counterions BF () and PF () were synthesized in order to check their behavior in forming molecular/crystal structures. This allows comparison with the final products of analogous syntheses performed with similar bidentate ligands containing methyl substituents on the benzene ring, namely 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene () and 1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (). The Ag(I) complexes obtained with the methylated ligands mentioned above form isostructural pairs of waved 1D chains or dinuclear boxes, of general formula {[Ag()]X} and [Ag()]X, respectively (X = BF, PF), under the same reaction conditions.
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