Electronic Structure of Triplet States of Zinc(II) Tetraphenylporphyrins

Walters, Valerie A.; Paula, Julio C. de; Jackson, Brian P.; Nutaitis, Charles; Hall, Kelly; Lind, Jeffrey; Cardozo, Kevin; Chandran, Kartik; Raible, Duane; Phillips, Charles M.

doi:10.1021/j100004a016

Cited by 48 publications

(55 citation statements)

References 9 publications

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“…This solvent was selected as a suitable polar solvent to stabilize a charge-separated state if an electron transfer process took place, which turned out not to be the case. After 2 ps, the resulting transient spectrum is practically identical to that of ZnTPP, tetraphenylporphyrin zinc(II) [35][36][37][38], indicating that donor 2 in its S 1 excited state has been generated. The latter transient species relaxes slowly with a rate of (~1.5 ns) -1 (analyzed as a single exponential).…”

Section: Energy Transfer Dynamicsmentioning

confidence: 80%

Decoupling the artificial special pair to slow down the rate of singlet energy transfer

Harvey

Langlois

Filatov

et al. 2012

J. Porphyrins Phthalocyanines

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Nature has designed efficient photosystems allowing microorganisms such as photo-bacteria to survive under particularly difficult environment due to scarcity of light [1]. In the photosynthetic membranes of these organisms, exciton (energy excitation migration), energy and electron transfers occur with impressing rates [1], and numerous research groups around the world attempted to design chemical models, which were recently reviewed by us [2]. One of the key components in both the natural and synthetic systems is the special pair [3,4]. Moreover, the various parameters controlling the rates for singlet energy transfer, k ET , in a general sense, was detailed ABSTRACT: Trimer 2, composed of a cofacial heterobismacrocycle, octamethyl-porphyrin zinc(II) and bisarylporphyrin zinc(II) held by an anthracenyl spacer, and a flanking acceptor, bisarylporphyrin free-base (Ar = -3,5-(tBu) 2 C 6 H 3 ), has been studied by means of absorption spectroscopy, "steady state and time-resolved fluorescence" and fs transient absorption spectroscopy, and density functional theory (DFT) in order to assess the effect of decoupling the chromophores' low energy MOs on the rate of the singlet, S 1 , energy transfer, k ET , compared to a recently reported work on a heavily coupled trimeric system, Trimer 1, [biphenylenebis(n-nonyl)porphyrin zinc(II)]-bisarylporphyrin free-base (Ar = -3,5-(tBu) 2 C 6 H 3 ). The position of the 0-0 peaks of the absorption and fluorescence spectra of Trimer 2 indicates that these porphyrin units are respectively energy donor 1, donor 2, and acceptor. The DFT computations confirm that the MOs of the cofacial donor 1-donor 2 dyad are decoupled, but significant MO coupling between donor 2 and acceptor 1 is still present despite the strong dihedral angle between their respective average planes (77.5°: geometry optimization by DFT). The fs transient absorption spectra exhibit a clear S 1 -S n fingerprint of the bisarylporphyrin zinc(II) chromophore and the kinetic trace exhibits a slow rise time of 87 ps, due to a S 1 donor 1 → donor 2 ET. The transient species donor 2 and acceptor decay respectively in the short (~1.5) ns and 6 ns time scale.

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Section: Energy Transfer Dynamicsmentioning

confidence: 80%

Decoupling the artificial special pair to slow down the rate of singlet energy transfer

Harvey

Langlois

Filatov

et al. 2012

J. Porphyrins Phthalocyanines

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“…The triplet state absorption spectrum of Zn(II)porphyrin is generally composed of two bands; one lies in the visible region and the other in the nearinfrared (IR) region. 25,26 While the near-infrared absorption in the triplet state corresponds to the transition between two states with singly excited configurations [a 1u (π),e g (π 26- 28 We have measured the triplet state absorption spectra of Zn(II) 5,15-bis(3,5-dioctyloxyphenyl) porphyrin monomer (Z1) and its mesomeso linked array compounds (Z2, Z3, Z6, and Z12) to investigate the change in the triplet state absorption spectra and their dynamics along with the increase of porphyrin moieties in the arrays.…”

Section: Resultsmentioning

confidence: 99%

Energy Relaxation Dynamics of Excited Triplet States of Directly Linked Zn(II)Porphyrin Arrays

Song

Cho

Yoon

et al. 2002

Bulletin of the Korean Chemical Society

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The energy relaxation dynamics of the lowest excited singlet and triplet states of the Zn(II)porphyrin monomer and its directly linked arrays were comparatively investigated with increasing the number of porphyrin moieties. While the fluorescence decay rates and quantum yields of the porphyrin arrays increased with the increase of porphyrin units, their triplet-triplet (T-T) absorption spectra and decay times remained almost the same. The difference in the trends of energy relaxation dynamics between the excited singlet and triplet states has been discussed in view of the electronic orbital configurations.

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“…The latter is, however, to some extent masked by the much stronger ZnP triplet excited state as well as C 60 triplet excited state features. 55,56 Careful analyses of the absorption time profiles in the 600-700 nm and 900-1100 nm region enables the analysis of the chargetransfer rates of the ZnP radical cation and the C 60 radical anion, respectively. The charge separation lifetimes in anisole are 25 ps for C 60 -pyr·ZnP, 2 ps for C 60 -PPV1-pyr·ZnP, and 23 ps for C 60 -PPV3-pyr·ZnP.…”

Section: Time-resolved Photophysical Characterizationmentioning

confidence: 99%

Tuning the reorganization energy of electron transfer in supramolecular ensembles – metalloporphyrin, oligophenylenevinylenes, and fullerene – and the impact on electron transfer kinetics

et al. 2015

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Oligo(p-phenylenevinylene) (oPPV) wires of various lengths featuring pyridyls at one terminal and C 60 moieties at the other, have been used as molecular building blocks in combination with porphyrins to construct a novel class of electron donor-acceptor architectures. These architectures, which are based on non-covalent, directional interactions between the zinc centers of the porphyrins and the pyridyls, have been characterized by nuclear magnetic resonance spectroscopy and mass spectrometry. Complementary physico-chemical assays focused on the interactions between electron donors and acceptors in the ground and excited states. No appreciable electron interactions were noted in the ground state, which was being probed by electrochemistry, absorption spectroscopy, etc.; the electron acceptors are sufficiently decoupled from the electron donors. In the excited state, a different picture evolved. In particular, steady-state and time-resolved fluorescence and transient absorption measurements revealed substantial electron donor-acceptor interactions. These led, upon photoexcitation of the porphyrins, to tunable intramolecular electron-transfer processes, that is, the oxidation of porphyrin and the reduction of C 60 . In this regard, the largest impact stems from a rather strong distance dependence of the total reorganization energy in stark contrast to the distance independence seen for covalently linked conjugates.

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Electronic Structure of Triplet States of Zinc(II) Tetraphenylporphyrins

Cited by 48 publications

References 9 publications

Decoupling the artificial special pair to slow down the rate of singlet energy transfer

Decoupling the artificial special pair to slow down the rate of singlet energy transfer

Energy Relaxation Dynamics of Excited Triplet States of Directly Linked Zn(II)Porphyrin Arrays

Tuning the reorganization energy of electron transfer in supramolecular ensembles – metalloporphyrin, oligophenylenevinylenes, and fullerene – and the impact on electron transfer kinetics

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