[en] Short communication

No abstract available

[en] Long-range electron transfer investigations of hemoproteins, blue copper and iron-sulphur proteins frequently rest on electronically excited metal centres. When the excitation energy approaches the oxidation of reduction potentials of intermediate residues the super-exchange view normally used, however, fails and a variety of new dynamic features arise. These all involve population of intermediate cation or anion residue states which can be partially or wholly vibrationally relaxed. Suitable views and a new theoretical formalism for these phenomena are discussed. The authors also note some important implications for site-directed mutagenesis in long-range, strongly exothermic electron transfer processes. (author). 36 refs.; 4 figs

[en] The basic physical principles underlying electron transfer between metal ions and other well-localised centres are summarized. Recent experimental progress is reviewed, with particular reference to electron transfer in the gas phase-between large molecules; in solution - results of volume of activation studies; and in the solid phase-transfer between paramagnetic centres. The potential value of neutron scattering spectroscopy, as a probe of low-energy electronic transitions in mixed-value materials, and as a method of measuring rate processes in the range 10¹⁰-10¹² s^-1, is discussed. (author). 86 refs.; 6 figs

[en] This paper compares intramolecular long distance electron transfer (ET) and triplet energy transfer (TT using two similar series of model compounds in which the donor and acceptor distance is varied in an identical way by employing common rigid spacer groups with identical stereochemical attachments in both series. It is found that transfer rates in the two series are correlated in a quantitative way. The results support a simple model which views TT as a simultaneous two-electron two-site exchange. The model is discussed in terms of the corresponding HOMO and LUMO overlap integrals

[en] This response article aims to provide an overview of the literature highlighting experimental work that, in contrast to the account by Luque and Schmickler, evidences the non-adiabatic nature of the electron transfer process

[en] Salaniline, a condensation product of salicylaldehyde and aniline, shows “off–on” fluorescent behaviour with pH in 1:1 (v/v) CH₃CN:H₂O and when 3% (w/v) anionic sodium dodecylsulphate (SDS) surfactant is present. The fluorescent switch behaviour of salaniline is forced to “off–on–off” type by 3% (w/v) neutral triton X-100 (TX-100) and 3% (w/v) cationic cetyltrimethylammonium bromide (CTAB) surfactant. The fluorescent “on” window is observed in the pH range 8.0–12.5 for TX-100 and 7.0–11.0 for CTAB. Different charge nature of the surfactants affects the protonation/deprotonation behaviour of salaniline differently, hence the photoinduced electron transfer (PET) processes and the fluorescent switch behaviour. -- Highlights: • Salicylideneaniline act as pH dependent “off–on” fluorescent switch in 1:1 (v/v) CH₃CN:H₂O. • In surfactant micelles TX-100 (neutral) and CTAB (positive) make the fluorescent switch “off–on–off” type while in. • In surfactant micelle SDS (negative) the pH dependent fluorescent switch is “off–on” type

[en] Highlights: • Evaluating the antioxidant activities of C₆₀ flavonoid conjugates. • Validation of the performance of two layer ONIOM(ROB3LYP/6-311++G(2df,2p)/PM6). • Predicting the favored site of reaction between malonate flavonoid derivatives and C_60. • Effect of C₆₀ on the BDE(O–H)s and IEs of C₆₀ flavonoid conjugates. Antioxidant properties of C₆₀ flavonoid conjugates were computationally examined via their O–H bond dissociation enthalpies (BDEs) and ionization energies (IEs) using two-layer ONIOM and PM6 methods, respectively. Eight ONIOM((RO)B3LYP/6-311++G(2df,2p):PM6) models were evaluated by computing BDE(O–H)s of a series of polyphenol. Synthetic mechanism of C₆₀ flavonoid conjugates was also explored via the potential energy surfaces of reaction between C₆₀ and malonate flavonoid derivatives (chalcone, flavone and flavanone) at the B3LYP/6-31G(d)//PM6. Antioxidant activities of C₆₀ flavonoid conjugates were discussed via hydrogen atom transfer, single electron transfer mechanisms and the effect of C₆₀ on the BDE(O–H)s and IEs of these compounds.

[en] We study in this paper the dynamics induced by models for photochemical water cleavage systems, focusing on the spatial and temporal factors influencing electron transfer and charge separation processes in such systems. The reaction-diffusion theory is formulated in full generality and the consequences explored in a number of spatio-temporal regimes, viz. the spatially homogeneous system in the long-time limit (i.e. the steady state for a well-stirred system), the spatially homogeneous system in evolution, and the spatially inhomogeneous system in evolution (where, in the latter study, we consider electron transfer at the cluster surface to be governed by a rate constant that reflects the localized nature of such processes). The results of numerical simulations are presented for all three cases and used to highlight the importance of heterogeneous environments in enhancing the cage escape yield of charge separated species, and to demonstrate the dependence of the hydrogen yield on the localization of electron-transfer processes in the vicinity of the microcatalyst surface

[en] Outer sphere electron transfer reactions on pure metal electrodes are often adiabatic and hence independent of the electrode material. Since it is not clear, whether adiabatic electron transfer can also occur on a semi-metal like graphite, we have re-investigated experimental data presented in a recent communication by Nissim et al. [Chemical Communications 48 (2012) 3294] on the reactions of quinones on graphite. We have supplemented their work by DFT calculations and conclude, that these reactions are indeed adiabatic. This contradicts the assertion of Nissim et al. that the rates are proportional to the density of states at the Fermi level