Luminescence from diplatinum(III) tetraphosphate complexes: dynamics of emissive d.sigma.* excited states

Shin, Yeung Gyo K.; Miskowski, Vincent M.; Nocera, Daniel G.

doi:10.1021/ic00337a024

Cited by 27 publications

(33 citation statements)

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“…It is consequently inefficiently orientated for overlap with the Ow component of the 8b 3u orbital, which lies along the Pt−Pt axis, and the resultant oscillator strength is very low. A very weak transition is observed at ∼22 500 cm -1 , which we assign to the corresponding spin−triplet transition which is expected to be some 3000−5000 cm -1 lower in energy than the spin−singlet transition …”

Section: Electronic Spectramentioning

confidence: 73%

“…The electronic spectra of Pt(III) lantern complexes [Pt 2 (pop) 4 L 2 ] n- (pop = H 2 P 2 O 5 2- ) have been extensively investigated. − More recently, detailed electronic spectroscopy studies of the sulfate [Pt 2 (SO 4 ) 4 L 2 ] n - and hydrogen phosphate complexes [Pt 2 (HPO 4 ) 4 L 2 ] n - have been reported. − We have also reported the electronic spectra of the Pt(III) complexes [Pt 2 (O 2 CCH 3 ) 4 L 2 ] n - (L = Cl, Br, OAc, H 2 O) 4 and found their spectra to be very similar to the sulfate and hydrogen phosphate bridged counterparts. The analysis and assignment of the electronic spectra of all of these Pt(III) complexes has relied heavily on the electronic structure determined for the isoelectronic rhodium(II) complexes Rh(O 2 CH 3 ) 4 L 2 (L = H 2 O, PH 3 ) from Xα−SW calculations. , However, the very recent MCD analysis of the [Pt 2 (SO 4 ) 4 L 2 ] 4- and [Pt 2 (HPO 4 ) 4 L 2 ] 4- (L = H 2 O, Cl, Br) complexes 14 is in conflict with certain of these assignments, in particular, the location of the intense σ(Pt 2 ,L) → σ*(Pt 2 ) transition.…”

Section: Introductionmentioning

confidence: 99%

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Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂

et al. 1996

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The electronic structure and metal-metal bonding in the classic d(7)d(7) tetra-bridged lantern dimer [Pt(2)(O(2)CCH(3))(4)(H(2)O)(2)](2+) has been investigated by performing quasi-relativistic Xalpha-SW molecular orbital calculations on the analogous formate-bridged complex. From the calculations, the highest occupied and lowest unoccupied metal-based levels are delta(Pt(2)) and sigma(Pt(2)), respectively, indicating a metal-metal single bond analogous to the isoelectronic Rh(II) complex. The energetic ordering of the main metal-metal bonding levels is, however, quite different from that found for the Rh(II) complex, and the upper metal-metal bonding and antibonding levels have significantly more ligand character. As found for the related complex [W(2)(O(2)CH)(4)], the inclusion of relativistic effects leads to a further strengthening of the metal-metal sigma bond as a result of the increased involvement of the higher-lying platinum 6s orbital. The low-temperature absorption spectrum of [Pt(2)(O(2)CCH(3))(4)(H(2)O)(2)](2+) is assigned on the basis of Xalpha-SW calculated transition energies and oscillator strengths. Unlike the analogous Rh(II) spectrum, the visible and near-UV absorption spectrum is dominated by charge transfer (CT) transitions. The weak, visible bands at 27 500 and 31 500 cm(-)(1) are assigned to Ow --> sigma(Pt(2)) and OAc --> sigma(Pt(2)) CT transitions, respectively, although the donor orbital in the latter transition has around 25% pi(Pt(2)) character. The intense near-UV band around 37 500 cm(-)(1) displays the typical lower energy shift as the axial substituents are changed from H(2)O to Cl and Br, indicative of significant charge transfer character. From the calculated oscillator strengths, a number of transitions, mostly OAc --> sigma(Pt-O) CT in nature, are predicted to contribute to this band, including the metal-based sigma(Pt(2)) --> sigma(Pt(2)) transition. The close similarity in the absorption spectra of the CH(3)COO(-), SO(4)(2)(-), and HPO(4)(2)(-) bridged Pt(III) complexes suggests that analogous spectral assignments should apply to [Pt(2)(SO(4))(4)(H(2)O)(2)](2)(-) and [Pt(2)(HPO(4))(4)(H(2)O)(2)](2)(-). Consequently, the anomalous MCD spectra reported recently for the intense near-UV band in the SO(4)(2)(-) and HPO(4)(2)(-) bridged Pt(III) complexes can be rationalized on the basis of contributions from either SO(4) --> sigma(Pt-O) or HPO(4) --> sigma(Pt-O) CT transitions. The electronic absorption spectrum of [Rh(2)(O(2)CCH(3))(4)(H(2)O)(2)] has been re-examined on the basis of Xalpha-SW calculated transition energies and oscillator strengths. The intense UV band at approximately 45 000 cm(-)(1) is predicted to arise from several excitations, both metal-centered and CT in origin. The lower energy shoulder at approximately 40 000 cm(-)(1) is largely attributed to the metal-based sigma(Rh(2)) --> sigma(Rh(2)) transition.

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Section: Electronic Spectramentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂

et al. 1996

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“…Emission spectra were recorded on a high-resolution instrument . The luminescence produced upon excitation with the 266-nm wavelength light from a Hg−Xe lamp was captured with a R943-02 Hamamatsu photomultiplier tube as the detector.…”

Section: Methodsmentioning

confidence: 99%

Mechanism for the Sensitized Luminescence of a Lanthanide Ion Macrocycle Appended to a Cyclodextrin

et al. 1998

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Aromatic hydrocarbons trigger a green luminescence on their association to a β-cyclodextrin (CD) modified with a Tb3+ diethylenetriaminepentaacetic acid (DTPA) macrocycle strapped across the bottom of the CD cup, [β-CD∪2(Tb⊂DTPA)]. The mechanism of this enhanced luminescence response is investigated with biphenyl as the aromatic hydrocarbon. Time-resolved emission spectroscopy reveals that excitation energy at the Tb3+ ion appears 12 μs after light is absorbed by biphenyl included within the CD cup. Excitation spectra are consistent with a photophysical mechanism comprising absorption-energy transfer-emission (AETE) from the aromatic hydrocarbon bound to the cavity of CD to the DTPA-encapsulated Tb3+ ion. A comparison of the luminescence decay kinetics for biphenyl associated to [β-CD∪2(Tb⊂DTPA)] and [β-CD∪2(Gd⊂DTPA)] complexes indicates that the pathway for the AETE process is absorption to the singlet excited state followed by intersystem crossing to the triplet, from which energy is transferred to the lanthanide ion.

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“…Methods and Instrumentation. Rate constants for the quenching of the Ru II diimine excited states by cyt c were obtained by lifetime and transient absorption measurements using laser instrumentation that has previously been described. , Stock solutions (25 or 50 mL) containing 6 × 10 -5 M of Ru II complex were prepared in μ = 0.1 M, pH = 7.4 phosphate buffer. The protein was dissolved in 200 μL of stock solution and placed in a 1 mm path length cuvette equipped with a stopcock.…”

Section: Methodsmentioning

confidence: 99%

Bimolecular Electron Transfer in the Marcus Inverted Region

et al. 1996

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The rates for the photoinduced bimolecular reactions of a homologous series of RuII diimines with cytochrome (cyt) c in its oxidized and reduced forms have been measured. The electronic coupling and reorganization energy of the system have been adjusted such that the inverted region may be accessed at reasonable driving forces. The electron transfer (ET) rate constants for *RuII diimine/FeIIcyt c reaction increase monotonically and approach the diffusion limit of 8.8 × 108 M-1 s-1 at ΔG° = −0.7 V. At a higher driving force, which may be accessed with the powerfully oxidizing *Ru(diCF3-bpy)3 2+, the rate for ET is observed to drop off. Similarly, the high driving forces achieved with *RuII diimine/FeIIIcyt c (−ΔG ≥ 1.12 V) are manifested in a decrease of the ET rate constant with increasing exergonicity. The observed ET rates for both systems are well described by a bimolecular model for ET occurring over an equilibrium distribution of reactant separation distances, each having a different formation probability and weighted by the first-order ET rate constant. The unique observation of bimolecular ET in the inverted region is not due to a peculiar reaction pathway engendered by the RuII diimines, which react as do other small-molecule cations at the solvent-exposed edge of the heme. The inherent ET properties of cyt c engender a Marcus curve that is displaced below the diffusion limit and shifted to smaller driving forces.

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Luminescence from diplatinum(III) tetraphosphate complexes: dynamics of emissive d.sigma.* excited states

Cited by 27 publications

References 2 publications

Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂

Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂

Mechanism for the Sensitized Luminescence of a Lanthanide Ion Macrocycle Appended to a Cyclodextrin

Bimolecular Electron Transfer in the Marcus Inverted Region

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Luminescence from diplatinum(III) tetraphosphate complexes: dynamics of emissive d.sigma.* excited states

Cited by 27 publications

References 2 publications

Electronic Structure of [Pt2(μ-O2CCH3)4(H2O)2]2+ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh2(μ-O2CCH3)4(H2O)2

Electronic Structure of [Pt2(μ-O2CCH3)4(H2O)2]2+ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh2(μ-O2CCH3)4(H2O)2

Mechanism for the Sensitized Luminescence of a Lanthanide Ion Macrocycle Appended to a Cyclodextrin

Bimolecular Electron Transfer in the Marcus Inverted Region

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Product

Resources

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Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂

Electronic Structure of [Pt₂(μ-O₂CCH₃)₄(H₂O)₂]²⁺ Using the Quasi-Relativistic Xα−SW Method: Analysis of Metal−Metal Bonding, Assignment of Electronic Spectra, and Comparison with Rh₂(μ-O₂CCH₃)₄(H₂O)₂