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A series of Ag( i ) and Cu( i ) complexes [Ag 3 (L 1 ) 2 ][PF 6 ] 3 ( 8 ), [Ag 3 (L 2 ) 2 ][PF 6 ] 3 ( 9 ), [Cu(L 1 )][PF 6 ] ( 10 ) and [Cu(L 2 )][PF 6 ] ( 11 ) have been synthesized by reactions of the tridentate amine-bis(N-heterocyclic carbene) ligand precursors [H 2 L 1 ][PF 6 ] 2 ( 6 ) and [H 2 L 2 ][PF 6 ] 2 ( 7 ) with Ag 2 O and Cu 2 O, respectively. Complexes 10 and 11 can also be obtained by transmetalation of 8 and 9 , respectively, with 3.0 equiv. of CuCl. A heterometallic Cu/Ag–NHC complex [Cu 2 Ag(L 1 ) 2 (CH 3 CN) 2 ][PF 6 ] 3 ( 12 ) is formed by the reaction of 8 with 2.0 equiv. of CuCl. All complexes have been characterized by NMR, electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffraction studies. The luminescence properties of 10–12 in solution and the solid state have been studied. At room temperature, 10–12 exhibit evident luminescence in solution and the solid state. The emission wavelengths are found to be identical at 483 nm in CH 3 CN, but they are 484, 480 and 592 nm in the solid state for 10–12 , respectively. These results suggest that 12 dissociates into two molecules of 10 and Ag( i ) ions in solution. Complex 12 is the first luminescent heterometallic Cu/Ag–NHC complex.
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This content will become publicly available on January 28, 2026
Increasing excited state lifetimes of Cu( i ) coordination complexes via strategic surface binding
Molecules undergo a structural change to minimize the energy of excited states generated via external stimuli such as light. This is particularly problematic for Cu(I) coordination complexes which are an intriguing alternative to the rare and expensive transition metal containing complexes (e.g., Pt, Ir, Ru, etc.) but suffer from short excited state lifetimes due to D2d to D2 distortion and solvent coordination. Here we investigate strategic surface binding as an approach to hinder this distortion and increase the excited state lifetime of Cu(I) polypyridyl complexes. Using transient absorption spectroscopy, we observe a more than 20-fold increase in excited state lifetime, relative to solution, for a Cu(I) complex that can coordinate to the ZrO2 via both carboxylated ligands. In contrast, the Cu(I) complex that coordinates via only one ligand has a less pronounced enhancement upon surface binding and exhibits greater sensitivity to coordinating solvents. A combination of ATR-IR and polarized visible ATR measurements as well as theoretical calculations suggest that the increased lifetime is due to surface binding which decreases the degrees of freedom for molecular distortion (e.g., D2d to D2), with the doubly bound complex exhibiting the most pronounced enhancement.
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- Award ID(s):
- 2246932
- PAR ID:
- 10590517
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Inorganic Chemistry Frontiers
- Volume:
- 12
- Issue:
- 3
- ISSN:
- 2052-1553
- Page Range / eLocation ID:
- 1295 to 1302
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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