Syntheses, characterization and sensitized lanthanide luminescence of heteronuclear Pt–Ln (Ln=Eu, Nd, Yb) complexes with 2,2′-bipyridyl ethynyl ligands

Ni, Jun; Zhang, Liyi; Chen, Xiaoming

doi:10.1016/j.jorganchem.2008.10.051

Cited by 25 publications

(1 citation statement)

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“…The excited state properties of Pt(II) acetylides continue to inspire both fundamental and applied interdisciplinary research in photonics. − Of particular interest are square planar bipyridyl and terpyridyl charge transfer (CT) acetylide chromophores which produce an array of photophysical responses, tunable through both the electronic structure of the ligand framework and/or solvent medium. − Such flexibility results in the ability to finely tune absorption/emission spectra, excited state lifetimes, emission quantum yields, and transient absorption features. − These criteria are of the utmost importance as they present a unique opportunity for the development of systematic structure−property relationships, − potentially exploitable in broadband optical limiting chromophore design. − We note that a variety of Pt(II) terpyridyl acetylide molecules have been shown to exhibit strong reverse saturable absorption (RSA), ,,− resulting from the fact that these chromophores generally produce large absorption transients throughout the visible and near-IR in the CT excited state. Interested in the origin of these strong transients, we pu...…”

Section: Introductionmentioning

confidence: 99%

Excited State Absorption Properties of Pt(II) Terpyridyl Complexes Bearing π-Conjugated Arylacetylides

Wang

Goeb

et al. 2010

J. Phys. Chem. B

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The synthesis, photophysics, and excited state absorption properties of three platinum(II) terpyridyl acetylide charge transfer (CT) complexes possessing a lone ancillary ligand systematically varied in phenylacetylide (PA) π-conjugation length, [Pt((t)Bu(3)tpy)([C≡C-C(6)H(4)](n)-H)]ClO(4) (n = 1, 2, 3), are described. Density functional theory (DFT) calculations performed on the ground states of complexes 1, 2, and 3 reveal that their HOMOs reside mainly on the ancillary π-conjugated PA moiety, ranging from 86 to 97%, with LUMOs predominantly centered on the terpyridyl acceptor ligand (91-92%). This electronic structure leads to the production of a triplet ligand-to-ligand CT ((3)LLCT) excited state upon visible light excitation with minor contributions from the corresponding triplet metal-to-ligand CT ((3)MLCT) excited state. Unusually strong red-to-near-IR transient absorptions are produced in the excited states of these molecules following selective long wavelength visible excitation of the low energy CT bands that do not emanate from the terpyridyl radical anion produced in the CT excited state or from an arylacetylide-based triplet intraligand ((3)IL) excited state. The extinction coefficients of these low energy absorption transients were determined using the energy transfer method with anthracene serving as the triplet acceptor. A detailed theoretical investigation using DFT and TDDFT methods reveals that these intense near-IR transient absorptions involve transitions resulting from transient oxidation of the PA subunit. In essence, the production of the (3)LLCT excited state transiently oxidizes the PA moiety by one electron, producing the corresponding highly absorbing radical cation-like species, analogous to that experienced in related intramolecular photoinduced electron transfer reactions. The computational work successfully predicts the oscillator strength and peak wavelength of the measured excited state absorption transients across this series of molecules. In the present effort, there is a convergence of theory and experiment given that the excited state absorption properties of these Pt(II) chromophores are determined by localized transitions that resemble open shell radical cation species.

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Section: Introductionmentioning

confidence: 99%

Excited State Absorption Properties of Pt(II) Terpyridyl Complexes Bearing π-Conjugated Arylacetylides

Wang

Goeb

et al. 2010

J. Phys. Chem. B

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Near‐Infrared (NIR) Luminescence from Lanthanide(III) Complexes

Chen

2010

Rare Earth Coordination Chemistry

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Elucidating the Mechanism of Efficient Eu(III) and Yb(III) Sensitisation from a Re(I) Tetrazolato Triangular Assembly

Wright,

Pfrunder,

Etchells

et al. 2024

Chemistry A European J

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The reaction of Re(CO)5Br with deprotonated 1H‐(5‐(2,2':6',2''‐terpyridine)pyrid‐2‐yl)tetrazole yields a triangular assembly formed by tricarbonyl Re(I) vertices. Photophysical measurements reveal blue‐green emission with a maximum at 520 nm, 32% quantum yield, and 2430 ns long‐lived excited state decay lifetime in deaerated dichloromethane solution. Coordination of lanthanoid ions to the terpyridine units red‐shifts the emission to 570 nm and also reveals efficient (90%) and fast sensitisation to both Eu(III) and Yb(III) at room temperature, with a similar rate constant kET of the order of 107 s‐1. Efficient sensitisation of Eu(III) from Re(I) is unprecedented, especially when considering the close proximity in energy between the donor and acceptor excited states. On the other hand, comparative measurements at 77 K reveal that energy transfer to Yb(III) is two orders of magnitude slower than that to Eu(III). A two‐step mechanism of sensitisation is therefore proposed, whereby the rate‐determining step is a thermally activated energy transfer step between the Re(I) centre and the terpyridine functionality, followed by rapid energy transfer to the respective Ln(III) excited states. At 77 K, the direct Re(I) to Eu(III) energy transfer seems to proceed via a ligand‐mediated superexchange Dexter‐type mechanism.

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Syntheses, characterization and sensitized lanthanide luminescence of heteronuclear Pt–Ln (Ln=Eu, Nd, Yb) complexes with 2,2′-bipyridyl ethynyl ligands

Cited by 25 publications

References 38 publications

Excited State Absorption Properties of Pt(II) Terpyridyl Complexes Bearing π-Conjugated Arylacetylides

Excited State Absorption Properties of Pt(II) Terpyridyl Complexes Bearing π-Conjugated Arylacetylides

Near‐Infrared (NIR) Luminescence from Lanthanide(III) Complexes

Elucidating the Mechanism of Efficient Eu(III) and Yb(III) Sensitisation from a Re(I) Tetrazolato Triangular Assembly

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