The triplet state of a platinum acetylide chromophore examined by time-resolved infrared spectroscopy and density functional theory

Cooper, Thomas M.; Blaudeau, Jean‐Philippe; Hall, Benjamin C.; Rogers, Joy E.; McLean, Daniel G.; Liu, Yonglin; Toscano, John P.

doi:10.1016/j.cplett.2004.10.132

Cited by 36 publications

(13 citation statements)

References 28 publications

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“…By analogy to DPP–Pt(acac) , the long wavelength band is essentially purely of HOMO → LUMO character; the MO plots reveal that Pt dπ orbitals contribute to the HOMO and to a lesser extent to the LUMO of the DPP chromophore. This observation is consistent with previous work on Pt–acetylide complexes featuring π-conjugated acetylide ligands, where it has been suggested that the long wavelength absorption may even have a small degree of Pt-to-ligand metal-to-ligand charge transfer (MLCT). − …”

Section: Resultssupporting

confidence: 92%

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

et al. 2014

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A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units.

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Section: Resultssupporting

confidence: 92%

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

et al. 2014

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“…The authors of this paper propose the intersystem crossing process occurs by coupling of S 1 state B 3u symmetry PtC⋮C antisymmetric stretch vibration to two uncoupled A 1 modes in the T 1 state. Similar spectroscopic behavior is observed in PE2 , where a cumulated CCC stretch vibration appears in the T 1 state vibration spectrum . Both of these experimental studies suggest, during intersystem crossing, conversion from aromatic ethynyl linkages to allene linkages occurs.…”

Section: Discussionsupporting

confidence: 71%

“…Time-resolved infrared spectra of the triplet state trans -Pt(PBu 3 ) 2 ((C⋮C−C 6 H 4 −C⋮CC 6 H 5 ) 2 give evidence the triplet state geometry has cumulene and quinone character. A related time-resolved infrared spectroscopy and theoretical study of trans -Pt(PBu 3 ) 2 (C⋮CC 6 H 5 ) 2 gives evidence the triplet exciton is confined to one ligand .…”

Section: Introductionmentioning

confidence: 99%

Asymmetry in Platinum Acetylide Complexes: Confinement of the Triplet Exciton to the Lowest Energy Ligand

et al. 2006

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To determine structure-optical property relationships in asymmetric platinum acetylide complexes, we synthesized the compounds trans-Pt(PBu3)2(C[triple bond]CC6H5)(C[triple bond]C-C6H4-C[triple bond]CC6H5) (PE1-2), trans-Pt(PBu3)2(C[triple bond]CC6H5)(C[triple bond]C-C6H4-C[triple bond]C-C6H4-C[triple bond]CC6H5) (PE1-3) and trans-Pt(PBu3)2(C[triple bond]C-C6H4-C[triple bond]CC6H5)(C[triple bond]C-C6H4-C[triple bond]C-C6H4-C[triple bond]CC6H5) (PE2-3) that have different ligands on either side of the platinum and compared their spectroscopic properties to the symmetrical compounds PE1, PE2 and PE3. We measured ground state absorption, fluorescence, phosphorescence and triplet state absorption spectra and performed density functional theory (DFT) calculations of frontier orbitals, lowest lying singlet states, triplet state geometries and energies. The absorption and emission spectra give evidence the singlet exciton is delocalized across the central platinum atom. The phosphorescence from the asymmetric complexes comes from the largest ligand. Time-dependent (TD) DFT calculations show the S1 state has mostly highest occupied molecular orbital (HOMO) --> lowest unoccupied molecular orbital (LUMO) character, with the LUMO delocalized over the chromophore. In the asymmetric chromophores, the LUMO resides on the larger ligand, suggesting the S1 state has interligand charge transfer character. The triplet state geometries obtained from the DFT calculations show distortion on the lowest energy ligand, whereas the other ligand has the ground state geometry. The calculated trend in the triplet state energies agrees very well with the experimental trend. Calculations of triplet state spin density also show the triplet exciton is confined to one ligand. In the asymmetric complexes the spin density is confined to the largest ligand. The results show Kasha's rule applies to these complexes, where the triplet exciton moves to the lowest energy ligand.

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“…There have been several reports of excited state infrared spectra for square-planar transition metal complexes of platinum involving phenylacetylide ligands that monitor the C ≡ C triple bond stretching wavenumber (22)(23)(24)(25). Of these, the most notable comparison to compounds II and II 0 is trans-Pt½ðCCPhÞ 2 ðPBu 3 Þ 2 in its 3 MLCT state (22).…”

Section: Resultsmentioning

confidence: 99%

Electron delocalization in the S ₁ and T ₁ metal-to-ligand charge transfer states of trans -substituted metal quadruply bonded complexes

Alberding

Chisholm

Gallucci

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Electron delocalization in the S 1 and T 1 metal-toligand charge transfer states of trans-substituted metal quadruply bonded complexes . These differences arise from consideration of the relative orbital energies of the M 2 δ or M 2 δ* and the ligand π Ã as well as the magnitudes of orbital overlap.excited state mixed valency | vibrational spectroscopy | potential energy surface | cyano group | ethynyl group C onjugated organic polymers have been intensely studied over the past two decades because of their fascinating optoelectronic properties. Aside from the sheer scientific curiosity that they aroused, it soon was recognized that a plastic electronics industry was possible and a good deal of this expectation has already been realized. Conjugated organic polymers find commercial applications as field-effect transistors (1), light emitting diodes (2), and photovoltaic devices (3, 4). As an extension of this field there is considerable interest in incorporating metal ions into conjugated organic systems and numerous reports are to be found in the literature concerning the role of metal ions in tailoring the optoelectronic properties of the organic conjugated systems. For example, the attachment of π-conjugated ligands to Ir(III) has allowed the luminescence to cover the entire region of the visible spectrum (5, 6) and the incorporation of Pt(II) into conjugated ethynylthiophenes has led to a significant enhancement of the efficiency of a bulk heterojunction photocell (7).Knowledge of electronic structure is key to the understanding of these properties and the ability to manipulate electronic structure by selection of metal-organic components holds the promise of custom design. The MM quadruply bonded unit (MM ¼ Mo 2 , MoW, or W 2 ) has many attractive features due to the tunability of the energy of the M 2 δ orbital by selection of the metal and its attendant ligands and due to M 2 δ to organic π-conjugation. In this report, we show how this can influence the charge dynamics and delocalization of singlet and triplet photo-excited states that may be delocalized or localized (valence trapped) metal-to-ligand charge transfer (MLCT) states or MMδδ* states. To achieve this we have prepared the trans-substituted compounds M 2 ðT i PBÞ 2 ðO 2 CC 6 H 4 -4-CNÞ 2 , where T i PB ¼ 2,4,6-triisopropylbenzoate and M ¼ Mo (I) or W (I 0 ), and M 2 ðO 2 CMeÞ 2 ððN½ i PrÞ 2 CC≡ CC 6 H 5 Þ 2 , where M ¼ Mo (II) or W (II 0 ), whose structures are shown in Fig. 1. Here, the bulky T i PB and amidinate ligands favor the trans-substitution and allow the extended conjugation of the two trans-ligands via Lπ-M 2 δ-Lπ conjugation. Evidence of this is seen in the molecular structures found in the solid-state that reveal the near coplanarity of the aryl groups of the p-cyanobenzoate and amidinate ligands in I and II 0 , respectively.The ground state geometry and symmetry of these discrete compounds presents a situation where added charge could reside on either of two interchangeable redox active ligand sites. This situation is, by definition,...

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The triplet state of a platinum acetylide chromophore examined by time-resolved infrared spectroscopy and density functional theory

Cited by 36 publications

References 28 publications

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

Asymmetry in Platinum Acetylide Complexes: Confinement of the Triplet Exciton to the Lowest Energy Ligand

Electron delocalization in the S ₁ and T ₁ metal-to-ligand charge transfer states of trans -substituted metal quadruply bonded complexes

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The triplet state of a platinum acetylide chromophore examined by time-resolved infrared spectroscopy and density functional theory

Cited by 36 publications

References 28 publications

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

Photophysics of Organometallic Platinum(II) Derivatives of the Diketopyrrolopyrrole Chromophore

Asymmetry in Platinum Acetylide Complexes: Confinement of the Triplet Exciton to the Lowest Energy Ligand

Electron delocalization in the S 1 and T 1 metal-to-ligand charge transfer states of trans -substituted metal quadruply bonded complexes

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Electron delocalization in the S ₁ and T ₁ metal-to-ligand charge transfer states of trans -substituted metal quadruply bonded complexes