Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Mohammed, Omar F.; Sarhan, Ahmed Aly Diaa Mohammed

doi:10.1016/j.chemphys.2010.04.014

Cited by 14 publications

(19 citation statements)

References 24 publications

(26 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This 0.5 ps time constant is ascribed to solvent reorganization based on the precedence of previously reported D−π−A complexes with Fc donors. 44 The observation that both the lifetimes for BET and the trend of lifetime vs ΔG°(though with a limited data set) are similar for the monoferrocenyl and diferrocenyl complexes suggests that excited-state Fe II /Fe III intervalence charge-transfer (IVCT) interactions in the Fe III −Ti III −Fe II excited state do not significantly affect the decay kinetics of the diferrocenyl complexes. Furthermore, our previous investigations showed no evidence of ground-state Fe III −Ti IV −Fe II IVCT in the one e − oxidized Cp 2 Ti(C 2 Fc) 2 CuBr complex.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

et al. 2019

View full text Add to dashboard Cite

Time-resolved transient absorption spectroscopy and computational analysis of D−π−A complexes comprising Fe II donors and Ti IV acceptors with the general formula R Cp 2 Ti(C 2 Fc) 2 (where R Cp = Cp*, Cp, and MeOOC Cp) and TMS Cp 2 Ti(C 2 Fc)(C 2 R) (where R = Ph or CF 3 ) are reported. The transient absorption spectra are consistent with an Fe III /Ti III metal-to-metal charge-transfer (MMCT) excited state for all complexes. Thus, excited-state decay is assigned to back-electron transfer (BET), the lifetime of which ranges from 18.8 to 41 ps. Though spectroscopic analysis suggests BET should fall into the Marcus inverted regime, the observed kinetics are not consistent with this assertion. TDDFT calculations reveal that the singlet metal-to-metal charge-transfer ( 1 MMCT) excited state for the Fe II /Ti IV complexes is not purely MMCT in nature but is contaminated with the higher-energy 1 Fc (d-d) state. For the diferrocenyl complexes, R Cp 2 Ti(C 2 Fc) 2 , the ratio of MMCT to Fc centered character ranges from 57:43 for the Cp* complex to 85:15 for the MeOOC Cp complex. For the diferrocenyl and monoferrocenyl complexes investigated herein, the excited-state lifetimes decrease with increased 1 Fc character. The effect of Cu I coordination was also analyzed by time-resolved transient absorption spectroscopy and reveals the elongation of the excited-state lifetime by 3 orders of magnitude to 63 ns. The transient spectra and TDDFT analysis suggest that the long-lived excited state in Cp 2 Ti(C 2 Fc) 2 •CuX (where X is Cl or Br) is a triplet iron species with an electron arrangement of Ti IV − 3 Fe II −Cu I .

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Previous reports on ferrocene-linked donor-accptor systems suggest that, such molecules tend to exhibit two lifetimes as the excited singlet (S 1 ) state has sufficient charge transfer (CT) character due to electron transfer from ferrocene unit to the acceptor unit. 32 This observation is in sync with the lower emission quantum yield of compound 5 due to ILCT, which facilitates nonradiative deactivation of the excited state. Furthermore, the lower quantum yields and short emission lifetimes for compounds 2, 3 and 5 suggest that other nonradiative decay processes (internal conversion and/or intersystem crossing from S 1 to T 1 ) might be more feasible in these compounds.…”

Section: Photophysical Studiesmentioning

confidence: 80%

Ferrocene and triphenylamine appended boranils

et al. 2018

View full text Add to dashboard Cite

Boranils containing ferrocene and triphenylamine groups were synthesized and well characterized by IR, 1 H, 13 C, 11 B and 19 F NMR and ESI-MS spectrometry. UV-Vis absorption, steady-state and time-resolved fluorescence techniques were employed to study their photophysical properties. The presence of electron rich substituents caused significant alterations in their absorption and emission spectra. As compared to the parent boranil compound (λ abs = 342 nm), boranil-triphenylamine and boranil-ferrocene conjugates exhibited red shifted absorption maxima (λ abs = 384, 375 nm, respectively). The boranil-triphenylamine and boranilferrocene conjugates displayed red shifted emission spectra (λ em = 524, 489 nm, respectively), as compared to the parent boranil (λ em = 471 nm). Also, large Stokes shifts (6217−6958 cm −1) were observed for both the conjugates in solution phase.

show abstract

“…Because we pumped the radical samples directly into the IV-CT band and all EADS1 present maxima in the same region as the respective EADS2, the former are attributed to the partially unrelaxed IV-CT states. 28,[99][100][101][102][103][104][105] These are the first states observed after excitation and their molecular geometry and/or solvation are similar to those of the ground state (see Fig. 11).…”

Section: Absorption Spectroscopymentioning

confidence: 81%

On the relation of energy and electron transfer in multidimensional chromophores based on polychlorinated triphenylmethyl radicals and triarylamines

Steeger¹,

Griesbeck²,

Schmiedel³

et al. 2015

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

A star-like compound consisting of a polychlorinated triphenylmethyl radical (PCTM) core linked to three triarylamines (TAA) and a symmetric and an asymmetric hexaarylbenzene (HAB) both substituted with three PCTMs and three TAAs were synthesised. In the star-like compound a strong communication between the redox centres was observed by electron paramagnetic resonance spectroscopy and UV/Vis/NIR absorption measurements, whereas in the HABs only a weak interaction could be detected. The temporal evolution of the excited states was monitored by ultrafast transient absorption measurements. Within the first picosecond stabilisation of the charge transfer state was observed induced by solvent rotation. Anisotropic transient absorption measurements revealed that within the lifetime of the excited state (τ = 1-4 ps) energy transfer does not occur in the HABs whereas in the star-like system ultrafast and possibly coherent energy redistribution is observed. Taken this information together we made the identity between energy transfer and electron transfer in the specific systems apparent.

show abstract

Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Cited by 14 publications

References 24 publications

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

Ferrocene and triphenylamine appended boranils

On the relation of energy and electron transfer in multidimensional chromophores based on polychlorinated triphenylmethyl radicals and triarylamines

Contact Info

Product

Resources

About

Ultrafast excited-state dynamics of ferrocene-bridge-acceptor system

Cited by 14 publications

References 24 publications

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an FeII to TiIV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an FeII to TiIV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

Ferrocene and triphenylamine appended boranils

On the relation of energy and electron transfer in multidimensional chromophores based on polychlorinated triphenylmethyl radicals and triarylamines

Contact Info

Product

Resources

About

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States

Picosecond to Nanosecond Manipulation of Excited-State Lifetimes in Complexes with an Fe^II to Ti^IV Metal-to-Metal Charge Transfer: The Role of Ferrocene Centered Excited States