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Room temperature ionic liquids (RT-ILs) are promising electrolytes for electrocatalysis. Understanding the effects of the electrode–electrolyte interface structure on electrocatalysis in RT-ILs is important. Ultrafast mass transport of redox species in N-methyl-N-ethyl-pyrrolidinium polybromide (MEPBr2n+1) enabled evaluation of the reorganization energy (λ), which reflects the solvation structure in the inner Helmholtz plane (IHP). λ was achieved by fitting the electron transfer rate-limited voltammogram at a Pt ultramicroelectrode (UME) to the Marcus–Hush–Chidsey model for heterogeneous electron transfer kinetics. However, it is time-consuming or even impossible to prepare electrode materials, including alloys of numerous compositions in the form of UME, for each experiment. Herein, we report a method to evaluate the λ of MEPBr2n+1 by scanning electrochemical cell microscopy (SECCM), which allows high throughput electrochemical measurements using a single electrode with high spatial resolution. Fast mass transport in the nanosized SECCM tip is critical for achieving heterogeneous electron transfer-limited voltammograms. Furthermore, investigating λ on a high-entropy alloy materials library composed of Pt, Pd, Ru, Ir, and Ag suggests a negative correlation between λ and the work function. Given that the potential of zero charge correlates with the work function of electrodes, this can be attributed to the surface-charge sensitive ionic structure in the IHP of MEPBr2n+1, modulating the solvation energy of the redox-active species in the IHP. [ABSTRACT FROM AUTHOR]

Understanding and predicting the charge transport properties of π-conjugated materials is an important challenge for designing new organic electronic devices, such as solar cells, plastic transistors, light-emitting devices, and chemical sensors. A key component of the hopping mechanism of charge transfer in these materials is the Marcus reorganization energy which serves as an activation barrier to hole or electron transfer. While modern density functional methods have proven to accurately predict trends in intramolecular reorganization energy, such calculations are computationally expensive. In this work, we outline active machine learning methods to predict computed intramolecular reorganization energies of a wide range of polythiophenes and their use toward screening new compounds with low internal reorganization energies. Our models have an overall root mean square error (RMSE) of ±0.113 eV, but a much smaller RMSE of only ±0.036 eV on the new screening set. Since the larger error derives from high-reorganization energy compounds, the new method is highly effective to screen for compounds with potentially efficient charge transport parameters. [ABSTRACT FROM AUTHOR]

Electron transfer in electrocatalysis involves strong short-range electronic interactions and occurs in an electrochemical double layer. Describing the two elements on an equal footing is an essential but challenging task for theoretical electrocatalysis. This work addresses this challenge using a mixed quantum–classical treatment. This treatment features the combination of chemisorption theory, electron transfer theory, and double layer theory in a unifying framework. Electrostatic free energy terms and solvent reorganization energy, key parameters modulating the electron transfer process, are calculated from a three-dimensional continuum double layer model that considers the reactant structure, steric effect, and solvent orientational polarization. The presented model is reduced back to the Marcus theory by neglecting electronic interactions and to the Schmickler theory of electrocatalysis by neglecting double layer effects. Emphasis is placed on understanding the multifaceted double layer effects in electrocatalysis. Apart from modifying the driving force and reactant concentration that are considered in the Frumkin corrections, double layer effects also modulate the interfacial solvent reorganization energy, thus adding a new term to the transfer coefficient. An additional level of intricacy comes into play if the reactant zone needs to replace solvent molecules originally adsorbed on the metal surface when it approaches the metal surface. The resulting free energy penalty shifts the transition state away from the metal surface and thus increases the activation barrier. Understanding how the metal surface charging condition modulates the interfacial stiffness opens an additional channel of deciphering electrolyte effects in electrocatalysis. [ABSTRACT FROM AUTHOR]

The kinetics for interfacial electron transfer (ET) from a transparent conductive oxide (tin-doped indium oxide, ITO, Sn:In2O3) to molecular acceptors 4-[N,N-di(p-tolyl)amino]benzylphosphonic acid, TPA, and [RuII(bpy)2(4,4′-(PO3H2)2-bpy)]2+, RuP, positioned at variable distances within and beyond the electric double layer (EDL), were quantified in benzonitrile and methanol by nanosecond absorption spectroscopy as a function of the thermodynamic driving force, −ΔG°. Relevant ET parameters such as the rate constant, ket, reorganization energy, λ, and electronic coupling, Hab, were extracted from the kinetic data. Overall, ket increased as the distance between the molecular acceptor and the conductor decreased. For redox active molecules within the Helmholtz planes of the EDL, ket was nearly independent of −ΔG°, consistent with a negligibly small λ value. Rips–Jortner analysis revealed a non-adiabatic electron transfer mechanism consistent with Hab < 1 cm−1. The data indicate that the barrier for electron transfer is greatly diminished at the conductor–electrolyte interface. [ABSTRACT FROM AUTHOR]

Improving the efficiency of photo-electrocatalytic cells depends on controlling the rates of interfacial electron transfer to promote the formation of long-lived charge separated states. Ultimately, for efficient catalytic assemblies to see widespread implementation, repeated electron transfer in the absence of charge recombination needs to be realized. In this study, a series of manganese-based transition metal complexes known to undergo charge transfer-induced spin crossover are employed to study how significant increases in inner-sphere reorganization energy affect the rates of interfacial electron transfer. Each complex is characterized by transient spectroscopic and electrochemical methods to calculate the rate of electron transfer to a model chromophore anchored to the surface of a TiO2 film. Likewise, open-circuit voltage decay measurements were used to determine the voltage-dependent lifetime of injected electrons in TiO2 in the presence of each complex. To further characterize the rates of electronic recombination, density functional theory was used to calculate the inner-sphere and outer-sphere reorganization energy for each complex. These calculations were then combined with classical Marcus theory to determine the theoretical rate of back-electron transfer from the TiO2 conduction band. These results show that, in model complexes, a significant reduction in the recombination rate constant is achieved for complexes possessing a significant inner-sphere reorganization energy. [ABSTRACT FROM AUTHOR]

Visible light excitation of the neutral complex [RuII(phen)2(bps)]0 (phen = 1,10-phenanthroline, bps = 4,7-biphenylsulfonate-1,10-phenanthroline) results in the formation of a triplet metal-to-ligand charge transfer excited state with a lifetime, τo, of 4.6 µs, where the promoted electron is localized on the bps ligand, 3*[RuIII(phen)2(bps•−)]0. The complex is dynamically quenched by di-n-heptyl-viologen, C7C7V2+, in solution and when the acceptor is embedded into negatively charged and neutral micelles. Addition of NaCl to solutions containing C7C7V2+ bound to negatively charged dodecyl sulfate sodium dodecyl sulfate micelles results in a monotonic increase in the quenching rate constant from kq = 6.0 × 107 to 1.7 × 109 M−1 s−1. In contrast, kq was independent of [NaCl] and diffusion limited in water and neutral micellar solution. Activated rate constants, kact, revealed that electron transfer was slowed by a factor of 450 when occurring in negatively charged micelle solution relative to neutral octaethylene glycol monododecyl ether (C12E8) micelles. In the 3*[RuIII(phen)2(bps•−)]0 excited state, the bps ligand is oriented away from the anionic micelle surface potential, −141 ≤ ψ ≤ −67 mV, due to a Frumkin effect operative in the deceleration of kact. Frumkin corrected rate constants were within a factor of three of those measured in C12E8 solution. Distance-dependent reorganization energies resulting from the orientation vary from 0.47 eV to 0.35 eV, while electronic coupling decreases by a factor of 10. The collective data show that orientation control over bimolecular rate constants in micellar solution can be achieved by screening micellar surface charges. [ABSTRACT FROM AUTHOR]

In this manuscript, we examine the role of image charge effects on the electrostatic potential fluctuations experienced by ionic species in the vicinity of an electrode surface. We combine simulation and theory to quantify these fluctuations and how they vary with distance from the electrode surface. We observe that the potential distribution narrows significantly for species within a few electrolyte screening lengths of the electrode. We attribute this narrowing to the effects of image charge fluctuations originating from the polarization response of the electrode. We show that the physical consequences of these image charge effects can be captured in the context of a simple analytical field theory with anti-symmetric boundary conditions. We contextualize these results by discussing their implications for rates of Marcus-like outer-sphere interfacial electron transfer. [ABSTRACT FROM AUTHOR]

Using a very recently proposed theoretical model, electron transfer rates in solution are calculated from first principles for different donor-acceptor pairs in tetrahydrofuran. We show that this approach, which integrates tunneling effects into a classical treatment of solvent motion, is able to provide reliable rate constants and their temperature dependence, even in the case of highly exergonic reactions, where Marcus' theory usually fails. [ABSTRACT FROM AUTHOR]

Many specific features of ultrafast electron transfer (ET) reactions in macromolecular compounds can be attributed to nonequilibrium configurations of intramolecular vibrational degrees of freedom and the environment. In photoinduced ET, nonequilibrium nuclear configurations are often produced at the stage of optical excitation, but they can also be the result of electron tunneling itself, i.e., fast redistribution of charges within the macromolecule. A consistent theoretical description of ultrafast ET requires an explicit consideration of the nuclear subsystem, including its evolution between electron jumps. In this paper, the effect of the multi-timescale nuclear reorganization on ET transitions in macromolecular compounds is studied, and a general theory of ultrafast ET in non-Debye polar environments with a multi-component relaxation function is developed. Particular attention is paid to designing the multidimensional space of nonequilibrium nuclear configurations, as well as constructing the diabatic free energy surfaces for the ET states. The reorganization energies of individual ET transitions, the equilibrium energies of ET states, and the relaxation properties of the environment are used as input data for the theory. The effect of the system-environment interaction on the ET kinetics is discussed, and mechanisms for enhancing the efficiency of charge separation in macromolecular compounds are analyzed. [ABSTRACT FROM AUTHOR]

Organic semiconductors have gained substantial interest as active materials in electronic devices due to their advantages over conventional semiconductors. We first designed four Schiff base compounds, then the effect of electron donor/acceptor groups (methyl/nitro) was studied on the compounds' electronic and transport nature. The absorption spectra (λabs) were computed by time-dependent DFT at TD-B3LYP/6-31+G** level. The effect of different solvents (ethanol, DMF, DMSO, and acetone) was investigated on the λabs. The substitution of the -NO2 group to the furan moiety at the 5th position in Compound 3 leads to a red-shift in the absorption spectrum. A smaller hole reorganization energy value in Compound 3 would be beneficial to get the hole's intrinsic mobility. In contrast, a reduced-electron reorganization energy value of Compound 4 than hole may result in enhanced electron charge transfer capabilities. The reorganization energies of compounds 1 and 2 exposed balanced hole/electron transport probability. The optical, electronic, and charge transport properties at the molecular level indicate that Compound 3 is suitable for organic electronic device applications. [ABSTRACT FROM AUTHOR]

Porphyrinoids are considered perfect candidates for their incorporation into electron donor–acceptor (D–A) arrays due to their remarkable optoelectronic properties and low reorganization energies. For the first time, a series of subphthalocyanine (SubPc) and corrole (Cor) were covalently connected through a short‐range linkage. SubPc axial substitution strategies were employed, which allowed the synthesis of the target molecules in decent yields. In this context, a qualitative synthetic approach was performed to reverse the expected direction of the different electronic events. Consequently, in‐depth absorption, fluorescence, and electrochemical assays enabled the study of electronic and photophysical properties. Charge separation was observed in cases of electron‐donating Cors, whereas a quantitative energy transfer from the Cor to the SubPc was detected in the case of electron accepting Cors. [ABSTRACT FROM AUTHOR]

Phenochalcogenazines such as phenoxazines and phenothiazines have been widely employed as photoredox catalysts (PCs) in small molecule and polymer synthesis. However, the effect of the chalcogenide in these catalysts has not been fully investigated. In this work, a series of four phenochalcogenazines is synthesized to understand how the chalcogenide impacts catalyst properties and performance. Increasing the size of the chalcogenide is found to distort the PC structure, ultimately impacting the properties of each PC. For example, larger chalcogenides destabilize the PC radical cation, possibly resulting in catalyst degradation. In addition, PCs with larger chalcogenides experience increased reorganization during electron transfer, leading to slower electron transfer. Ultimately, catalyst performance is evaluated in organocatalyzed atom transfer radical polymerization and a photooxidation reaction for C(sp2)−N coupling. Results from these experiments highlight that a balance of PC properties is most beneficial for catalysis, including a long‐lived excited state, a stable radical cation, and a low reorganization energy. [ABSTRACT FROM AUTHOR]

Since the key role of charge transfers (CT) states has been identified for organic solar cells (OSCs), research into their properties is a timely topic. Conventionally, their absorption and emission spectra are described in terms of Marcus' electron transfer theory. This is a single site approach with the essential parameter being the reorganization energy. Thus, it ignores ensemble effects, notably the role of static disorder that is inevitably present in a spin‐coated OSC film. Here time dependent photoluminescence spectroscopy is applied on blends of the polymeric donor MeLPPP with either the non‐fullerene acceptor SF‐PDI2 or with PC61BM within a temperature range from 295 to 5 K. The authors monitor how initially excited singlet states are converted to emissive CT states. Concomitantly, emission from residual singlets on the acceptor is observed rather than hybrid CT‐states. The role of spectral diffusion in this process is discussed. From the temperature and time dependent linewidths of absorption, fluorescence, and CT emission, the static and dynamic contributions to the total disorder are inferred. In both blends, at 295 K, the contribution of static disorder is comparable to the dynamic disorder. [ABSTRACT FROM AUTHOR]

In this contribution, a 1 : 2 mixed stack (⋯DADA⋯ arrangement) donor acceptor cocrystal comprising the hole transport material CBP (4,4′-bis(9H-carbazole-9-yl)biphenyl) as the donor (D) and TCNQ (7,7′,8,8′-tetracyano-1,4-quinodimethane) as the acceptor (A) was synthesized by the green method of mechano-chemical cocrystallization. Theoretical calculations predict n-type nature in the CBP:(TCNQ)2 cocrystal, which possesses a low band-gap (0.94 eV) with a stable LUMO energy (−4.49 eV), while the predominant hole transport nature of the donor CBP possessing a HOMO level (−5.31 eV) is reported. The switching of the p-type semiconductor nature of the donor CBP to the n-type nature in the CBP:(TCNQ)2 cocrystal has been elucidated in terms of two parameters of the charge transfer process, viz., charge transfer integral and reorganization energy, along with the frontier MO energy level. The role of the molecular structure of CBP, as well as the crystal packing to dictate the charge carrier property, is studied. Thus, the mechano-chemical charge transfer cocrystallization can be compared with heteroatom doping in silicon-based semiconductors to attain a switching of the polarity. [ABSTRACT FROM AUTHOR]

Graphene and graphene-derived materials have sparked a lot of interest because of their unique physico-chemical features, that have positioned graphene as a promising material for future opto-electronics, and energy-harvesting devices. Graphene possesses outstanding mechanical characteristics and chemical inertness, as well as great mobility and optical transparency. Single-layer graphene has a high optical transmissivity that allows it to pass through a wide variety of light wavelengths, making it a popular material for optically conducting windows. Graphene-based metal and metal oxide nanocomposites require substantial investigations to understand the fundamental interactions between nanostructures and the graphene surface in DSSC, for understanding the characteristic features of such nanocomposites. In the present study different donor-π-acceptor, systems were used, which are different in the type of the π –spacer units only. This D-π-A system was then decorated on a (TiO 2) 9 semiconductor leading to shifting of the absorption wavelength, the absorbed wavelength was further shifted upon interaction with tellurium–oxide@graphene, thereby exploring its application in solar energy harvesting devices. The result of such substitution was assessed in terms of various parameters such as highest occupied molecular orbital (HOMO), least unoccupied molecular orbital (LUMO), energy gap (E gap), maximum wavelength (λ max), the free energy of electron injection efficiency (ΔG inject), open-circuit voltage (V oc), reorganization energy (Δ reorg), etc by the DFT method with Gaussian 09 set of codes. The study can prove beneficial for understanding the mechanism of high optical absorption over a broad spectrum in such multijunction systems, the feature which makes them promising materials for efficient optical, electronic, and light-harvesting devices. [Display omitted] • D-π-A system was decorated on a (TiO 2) 9 semiconductor leading to shifting of the absorption wavelength • The absorbed wavelength was further shifted upon interaction with tellurium–oxide@graphene thereby exploring its application in solar energy harvesting devices. • The result of substitution was assessed in terms of various parameters like highest occupied molecular orbital (HOMO), least unoccupied molecular orbital (LUMO), energy gap (E gap), maximum wavelength (λ max), the free energy of electron injection efficiency (ΔG inject), open-circuit voltage (V oc), reorganization energy (Δ reorg), • DFT method with Gaussian 09 set of codes was used throughout the study. • From the study, it can be proven beneficial for understanding the high optical transmittance which allows a broad absorption of wavelength that refines its property designing as promising materials for efficient optical, electronic, and light-harvesting devices. [ABSTRACT FROM AUTHOR]

The multiredox reactivity of bioinorganic cofactors is often coupled to proton transfers. Here we investigate the structural, thermochemical, and electronic structure of ruthenium‐amino/amido complexes with multi‐ proton‐coupled electron transfer reactivity. The bis(amino)ruthenium(II) and bis(amido)ruthenium(IV) complexes [RuII(bpy)(en*)2]2+ (RuII‐H0) and [RuIV(bpy)(en*‐H2)2]2+ (RuIV‐H2) interconvert reversibly with the transfer of 2e−/2H+ (bpy=2,2'‐bipyridine, en*=2,3‐diamino‐2,3‐dimethylbutane). X‐ray structures allow correlations between the structural and electronic parameters, and the thermochemical data of the 2e−/2H+ multi‐square grid scheme. Redox potentials, acidity constants and DFT calculations reveal potential intermediates implicated in 2e−/2H+ reactivity with organic reagents in non‐protic solvents, which shows a strong inverted redox potential favoring 2e−/2H+ transfer. This is suggested to be an attractive system for potential one‐step (concerted) transfer of 2e−and 2H+ due to the small changes of the pseudo‐octahedral geometries and the absence of charge change, indicating a relatively small overall reorganization energy. [ABSTRACT FROM AUTHOR]

Using field-theoretic techniques, we develop a molecularly based dipolar self-consistent-field theory (DSCFT) for charge solvation in pure solvents under equilibrium and nonequilibrium conditions and apply it to the reorganization energy of electron transfer reactions. The DSCFT uses a set of molecular parameters, such as the solvent molecule's permanent dipole moment and polarizability, thus avoiding approximations that are inherent in treating the solvent as a linear dielectric medium. A simple, analytical expression for the free energy is obtained in terms of the equilibrium and nonequilibrium electrostatic potential profiles and electric susceptibilities, which are obtained by solving a set of self-consistent equations. With no adjustable parameters, the DSCFT predicts activation energies and reorganization energies in good agreement with previous experiments and calculations for the electron transfer between metallic ions. Because the DSCFT is able to describe the properties of the solvent in the immediate vicinity of the charges, it is unnecessary to distinguish between the inner-sphere and outer-sphere solvent molecules in the calculation of the reorganization energy as in previous work. Furthermore, examining the nonequilibrium free energy surfaces of electron transfer, we find that the nonequilibrium free energy is well approximated by a double parabola for self-exchange reactions, but the curvature of the nonequilibrium free energy surface depends on the charges of the electron-transferring species, contrary to the prediction by the linear dielectric theory. [ABSTRACT FROM AUTHOR]

Based on the quantum-mechanical theory of electron transfer (ET), the parameter was proposed to describe the electrochemical activity of doped graphenes. The parameter is calculated using the density of states (DOS), local density of state (LDOS) values, which are in turn obtained from the density functional theory (DFT) calculations and reorganization energies of redox system. DOS describes the contribution of the electronic structure of the electrode to the ET process, while the LDOS describes the electron density contribution of the atoms at some distance from the surface electrode. Reorganization energy corresponds to the restriction of solvation shell and bonds in redox system due to ET process. The overall contribution of these parameters enables a comprehensive assessment of the activity that is acceptable for semi-quantitative analysis. Calculations have shown that the proposed activity parameter correlates well with the calculated ET rate constants. Theoretical study of the oxygen reduction reaction (ORR) on graphene doped with p-elements in the framework of quantum-mechanical theory showed that ET activity decreases in series P-Gr > S-Gr > N-Gr > B-Gr > O-Gr > Gr. According to our estimates, the mixed or adiabatic regime of ET is probably observed on doped graphenes for all steps of ORR. Using N- and B-graphenes as an example and activity parameter, the influence of the applied potential and the atomic fraction of the doped element on the ET activity are studied. Image 1 • ET for O-, B-, N-Gr will proceed in mixed regime, while for S-, P-Gr ET is adiabatic. • ET activity will decrease in the order P-Gr > S-Gr > N-Gr > B-Gr > O-Gr > Gr. • Heteroatom and its first nearest neighbors will make the main contribution to the ET. • Shift of the Fermi level at the applied potential of Gr and B-, N-Gr is 0.1–0.2 eV/V. • Linear increase of ET activity from the atomic fraction of 1.4–4% B, N is observed. [ABSTRACT FROM AUTHOR]

Three linear dimers with two redox‐active planarized triphenylamines were synthesized and their structures verified by X‐ray crystallography. Their radical cations, which exhibit electron self‐exchange between the two redox centers, are of great interest. This process was thoroughly investigated by means of electron paramagnetic resonance spectroscopy, absorption spectroscopy, and (time‐dependent) density functional theory calculations. A comparison of the key parameters of electron transfer with non‐planarized nitrogen‐centered building blocks emphasizes the impact of using redox centers with low internal reorganization energies. However, the distance‐dependence attenuation factor of the super‐exchange mechanisms remains similar. [ABSTRACT FROM AUTHOR]

This study reports a long-lived 2 E photoexcited state (τ = 21 µs) of metal-oxo complex composed of only earth-abundant elements, which oxidizes toluene by the two-photon four-electron oxidation process with ∼200% quantum efficiency that is the highest value ever reported. [Display omitted] • A long-lived photoexcited state of a MnIV-oxo complex binding an acid. • Utilizing the high oxidizing power of a long-lived photoexcited state of acid-bound high valent metal-oxo complexes with the maximum quantum efficiency. • A photoinduced electron transfer from electron donors to the long-lived 2E excited state with a small reorganization energy. • A new way to achieve a photochemical oxidation of thermally inert substrates. The photoexcited state of high-valent metal-oxo complexes binding protons would show the much enhanced oxidizing reactivity, providing a new way to achieve a photochemical oxidation of thermally inert substrates. However, there has been only one example for the long-lived photoexcited state of a MnIV-oxo complex binding scandium ion that is a rare-earth metal element. We report herein the formation of a long-lived photoexcited state of a MnIV-oxo complex binding triflic acid, composed of only earth-abundant elements, which exhibits the highest oxidizing reactivity among the high-valent metal-oxo species, including the excited state, reported so far. Photoexcitation of a triflic acid-bound MnIV-oxo complex (1 , [(N4Py)MnIV(O)]2+–(HOTf) 2) in a deaerated trifluoroethanol/acetonitrile resulted in the formation of a long-lived photoexcited state with a lifetime of 21 μs, which oxidized toluene to produce benzyl alcohol that was further oxidized to benzaldehyde. The driving force dependence of the rate constant of the photoinduced electron transfer from electron donors to the long-lived 2 E excited state of 1 afforded a small reorganization energy of electron transfer (λ = 0.53 eV), since the 2 E excited state of 1 may be composed of the ligand-to-metal charge-transfer (LMCT) state and the efficient electron transfer to the excited sate of 1 occurs at the ligand center. The quantum efficiency of 200% was achieved for the photochemical four-electron oxidation of toluene by 1 , being the highest among various photooxidation reactions reported so far. The photodynamics were measured by laser-induced transient absorption spectroscopy to clarify the photooxidation mechanism of 1. [ABSTRACT FROM AUTHOR]

Five di‐ and tetracyano‐substituted pyrene‐fused pyrazaacenes were synthesized and studied as potential electron acceptors in the solid state. Single crystals of all compounds were grown and the crystal packing studied by DFT calculations (transfer integrals and reorganization energies) to get insight into possible use for semiconducting charge transport. [ABSTRACT FROM AUTHOR]

Biological electron transfer (ET) is one of the most studied biochemical processes due to its immense importance in biology. For many years, biological ET was explained using the classical incoherent transport mechanism, i.e. sequential hopping. One of the relatively recent major observations in this field is long-range extracellular ET (EET), where some bacteria were shown to mediate electrons for extremely long distances on the micrometer length scales across individual nanowires. This fascinating finding has resulted in several suggested mechanisms that might explain this intriguing EET. More recently, the structure of a conductive G. sulfurreducens nanowire has been solved, which showed a highly ordered quasi-1D wire of a hexaheme cytochrome protein, named OmcS. Based on this new structure, we suggest here several electron diffusion models for EET, involving either purely hopping or several degrees of mixed hopping and coherent transport, in which the coherent part is due to a local rigidification of the protein structure, associated with a decrease in the local reorganization energy. The effect is demonstrated for two closely packed heme sites as well as for longer chains containing up to several dozens porphyrins. We show that the pure hopping model probably cannot explain the reported conductivity values of the G. sulfurreducens nanowire using conventional values of reorganization energy and electronic coupling. On the other hand, we show that for a wide range of the latter energy values, the mixed hopping-coherent model results in superior electron diffusion compared to the pure hopping model, and especially for long-range coherent transport, involving multiple porphyrin sites. [ABSTRACT FROM AUTHOR]

A series of DMABN‐related compounds with two‐band fluorescence was studied by steady‐state absorption and fluorescence spectroscopy, time‐resolved absorption spectroscopy upon excitation with a 30‐fs laser pulse, and by TDDFT and xMCQDPT2 quantum chemical methods. The efficiency of the intramolecular electron transfer was found to depend on the excitation wavelength in MeCN. The reaction is described by a two‐state scheme (LE↔CT); the Stevens‐Ban method gives underestimated values for the reaction enthalpy ΔH (SB). The spectral luminescence and kinetic parameters, rate constants, and barriers for the forward (k1, Ea) and reverse (k−1, Ed) electron transfer were calculated. The Marcus plot for k1 versus the driving force (−ΔG) and the total reorganization energy (λ) were calculated for six compounds. It was shown that without a barrier, the 1/k1 value (267 fs) is close to the mean solvation time in MeCN (260 fs), ie, the reaction rate is completely determined by the solvent. The results of conformational analysis for all studied compounds are consistent with the twisted intramolecular charge transfer model of structural relaxation. [ABSTRACT FROM AUTHOR]

Possible electron transfer mechanisms have been studied for the reaction of 2,2′-diphenyl-1-picrylhydrazyl with a number of natural hydroxybenzenes in aqueous buffer solutions at pH = 2–9 using the methods of spectrophotometry and quantum chemical calculations. In acidic media, electron transfer occurs from the molecular form of hydroxybenzene to the radical with subsequent loss of proton, whereas in alkaline media the electron is transferred from the phenolate ion to the radical, preceded by the proton elimination step. Realization of a specific mechanism is indicated by the dependence of the reaction rate constant on the pH of the media and by the presence of correlation between the Gibbs free activation energy, calculated using the Marcus equation and that determined experimentally. [ABSTRACT FROM AUTHOR]

In the present work neuromuscular blocking rocuronium drugs were studied theoretically using the HF and B3LYP methods with the 3-21G, 6-31G, 6-311G, 6-31G (d, p) and CEP-31G basis sets. The transfer integrals (t) and the reorganization energies (λ) are calculated by applying the Marcus theory. The molecular and electronic properties such as molecular electrostatic potential (MEP) maps, partial state density (PDOS) spectrum and molecular orbitals (HOMO and LUMO) were presented. Molecular docking studies of rocuronium derivatives were performed for provided insights into the mechanism of action on ion channels that mediate rapid chemical neurotransmission at the neuromuscular junction. For the first time, it was found that the rocuronium molecule could be a good electron transfer material with respect to electron and hole reorganization energy values. The forbidden energy values of the rocuronium derivatives are at the range of −1.34 to −9.94 eV and in good agreement with the results for other signalling central nervous drugs. Image 1 • Electron and hole reorganization energies are calculated. • Transfer integrals and the reorganization energies are obtained by using Marcus theory. • It was found that, for the first time, the rocuronium molecule could be a good electron transfer material. [ABSTRACT FROM AUTHOR]

Quantum chemical modeling of Fe(III), Fe(II), and Fe(I) aqua-, aqua-hydroxo-, and aquadihydroxocomplexes is presented. The mechanism of a consecutive transfer of two electrons is studied as these forms are electrochemically reduced from an aqueous solution. The reorganization energy of the solvent and the inner sphere of studied reagents is calculated, standard redox potentials are estimated. Based on Marcus theory, the activation energy of two steps of Fe(III) reduction is estimated and the second electron transfer is shown to be rate controlling, while the energy barrier is increased due to the products of Fe(III) hydrolysis. The model predictions are in qualitative agreement with previously reported experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • Uses frontier molecular orbital energies as the source domain in transfer learning. • Utilizes reorganization energies as the target domain, minimizing data required. • Effective at predicting low reorganization energies. • Provides a convenient method for studying compound reorganization energies. • Accelerates research on material optical properties using this method. Reorganization energy, a crucial factor in quantum chemistry, plays an integral role in the research of optoelectronic and electrical devices such as organic field-effect transistors and organic light-emitting diodes. Currently, the calculation of reorganization energy predominantly depends on density functional theory, which poses significant computational costs. Traditional machine learning, commonly employed to predict reorganization energy necessitates a substantial volume of data for model training, a process that can be time-consuming due to difficulties in collecting sufficient data. This study proposes a novel solution by employing transfer learning. This method involves the pre-trained model using publicly accessible large-scale data on frontier molecular orbital energy, and then transfers this model to predict the reorganization energy. The experimental results indicate that the proposed method requires approximately 28% less data compared to traditional machine learning while maintaining equivalent accuracy. Moreover, this method achieved a median error of less than 0.02 eV when predicting low reorganization energy. Consequently, the need for reorganization energy data in model construction is significantly reduced, thus facilitating research into reorganization energy and expediting research into the optical properties of materials. [ABSTRACT FROM AUTHOR]

The concept of reorganization energy is well established for molecular systems where the electron transfer from a donor to an acceptor is accompanied by the reorganization of environment. It is not the case for bulk semiconductors with translational symmetry. However, in the presence of additional confinement, like in the quantum dots, the electron–phonon interaction is modified. We show that when the dots are not identical, the phonon reorganization energy can be determined. We calculate it for a realistic case of GaAs quantum dots. [ABSTRACT FROM AUTHOR]

The electron transfer (ET) rate in quantum dot (QD)-molecular acceptor systems is dependent upon system reorganization energy (RE, λ), which comprises contributions from solvent (λ 0) and reactants (λ i). However, to date, the effect of λ i on ET rate has been largely ignored. Herein, the ET from CdSe/ZnS QDs to 1-chloroanthraquinone (1-CAQ) in different solvents was investigated using ultrafa s t transient absorption spectroscopy as a means to evaluate the effect of λ i on ET rate. The results revealed that ET rate is strongly solvent dependent. Amazingly, the ET rate in carbon disulfide is 300-times higher than that in n -dodecane. Theoretical calculations indicated that the λ i contribution from 1-CAQ alone accounts for a large proportion of system RE and varies greatly in different solvents. Furthermore, the ET rate increases first and, then, decreases with the λ value in different solvents. This trend was interpreted consistently in terms of Marcus theory by adding λ i to λ for different solvents. Thus, our present work demonstrates that the RE of the acceptor molecule has a non-negligible effect on ET rate, providing new insight into the mechanisms of ET process and for the development of QD-based devices. Unlabelled Image • ET process was investigated between CdSe/ZnS and AQ by TA spectroscopy. • The ET rate exists an obvious distinction in different solvents. • The inner-sphere RE contribution is demonstrated to be an important influence on ET rate. • Changes of the inner-sphere RE induced by different solvent lead to the difference of ET rate. [ABSTRACT FROM AUTHOR]

The net electrostatic charge (Z) of a folded protein in solution represents a bird's eye view of its surface potentials—including contributions from tightly bound metal, solvent, buffer, and cosolvent ions—and remains one of its most enigmatic properties. Few tools are available to the average biochemist to rapidly and accurately measure Z at pH≠pI. Tools that have been developed more recently seem to go unnoticed. Most scientists are content with this void and estimate the net charge of a protein from its amino acid sequence, using textbook values of pKa. Thus, Z remains unmeasured for nearly all folded proteins at pH≠pI. When marveling at all that has been learned from accurately measuring the other fundamental property of a protein—its mass—one wonders: what are we missing by not measuring the net charge of folded, solvated proteins? A few big questions immediately emerge in bioinorganic chemistry. When a single electron is transferred to a metalloprotein, does the net charge of the protein change by approximately one elementary unit of charge or does charge regulation dominate, that is, do the pKa values of most ionizable residues (or just a few residues) adjust in response to (or in concert with) electron transfer? Would the free energy of charge regulation (ΔΔGz) account for most of the outer sphere reorganization energy associated with electron transfer? Or would ΔΔGz contribute more to the redox potential? And what about metal binding itself? When an apo‐metalloprotein, bearing minimal net negative charge (e.g., Z=−2.0) binds one or more metal cations, is the net charge abolished or inverted to positive? Or do metalloproteins regulate net charge when coordinating metal ions? The author's group has recently dusted off a relatively obscure tool—the "protein charge ladder"—and used it to begin to answer these basic questions. [ABSTRACT FROM AUTHOR]

We combine experimental and computational methods to address the anomalous kinetics of long-range electron transfer (ET) in mutants of Pseudomonas aeruginosa azurin. ET rates and driving forces for wild type (WT) and three N47X mutants (X = L, S, and D) of Ru(2,20-bipyridine)2 (imidazole)(His83) azurin are reported. An enhanced ET rate for the N47L mutant suggests either an increase of the donor–acceptor (DA) electronic coupling or a decrease in the reorganization energy for the reaction. The underlying atomistic features are investigated using a recently developed nonadiabatic molecular dynamics method to simulate ET in each of the azurin mutants, revealing unexpected aspects of DA electronic coupling. In particular, WT azurin and all studied mutants exhibit more DA compression during ET (>2 Å ) than previously recognized. Moreover, it is found that DA compression involves an extended network of hydrogen bonds, the fluctuations of which gate the ET reaction, such that DA compression is facilitated by transiently rupturing hydrogen bonds. It is found that the N47L mutant intrinsically disrupts this hydrogen-bond network, enabling particularly facile DA compression. This work, which reveals the surprisingly fluctional nature of ET in azurin, suggests that hydrogenbond networks can modulate the efficiency of long-range biological ET. [ABSTRACT FROM AUTHOR]

Discotic liquid crystal (DLC) materials have attracted considerable attention mainly due to their high charge carrier mobilities in quasi‐one‐dimensional columns. In this article, five hexaazatrinaphthylene‐based DLC molecules were investigated theoretically, and their frontier molecular orbital energy levels, crystal structures, and electron/hole drift mobilities were calculated by combination of density functional theory (DFT) and semiclassical Marcus charge transfer theory. The systems studied in this work include three experimentally reported molecules (1, 2, and 3) and two theoretically designed molecules (4 and 5). Compared with the 1–3 compounds, 4 and 5 have three more extended benzene rings in the π‐conjugated core. The present results show that the orders of the frontier molecular orbital energy levels and electron drift mobilities agree very well with the experiment. For 4 and 5, the electron/hole reorganization energies are lower than those of compounds 1–3. Furthermore, the calculated electron/hole transfer integral of 5 is the largest among all the five systems, leading to the highest electron and hole mobilities. In addition, the hydrophobicity and solubility were also evaluated by DFT, indicating that compound 5 has good hydrophobicity and good solubility in trichloromethane. As a result, it is expected that compound 5 can be a potential charge transport material in electronic and optoelectronic devices. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Intramolecular reorganization energy (RE) of molecules derived from the diketopyrrolopyrrole (DPP) unit has been studied using B3LYP/6-31G(d,p) theory. It was found that the replacement of the oxygen atoms with sulfur in the DPP unit led to a smaller RE for both the hole and electron transfer processes. One disadvantage of the sulfur replacement is the twist of the conjugated backbone, which might impair the π-π interactions in the solid state. The RE calculated from the adiabatic potential energy surfaces and that derived from the normal mode analysis agreed well for both systems. Electronic structure data showed that the replacement of oxygen atoms with sulfur in the DPP unit might lead to the development of ambipolar compounds with low RE. [ABSTRACT FROM AUTHOR]

Direct experimental determination of redox properties of superoxo (O2.−) and peroxo (O22−) embedded in dicopper complexes bearing an unsymmetrical binucleating ligand was achieved using cryo-electrochemistry and cryo-spectroelectrochemistry in dichloromethane. Cyclic voltammetry for dicopper(I) (1+) oxidation to a CuICuII mixed-valent species (12+) under inert atmosphere at 193 K reveals slow heterogeneous electron-transfer kinetics, indicative of a large reorganization energy. Oxygenation of the dicuprous complex 1+ gives the bridged peroxo dicopper(II) species 3+, which is reversibly oxidized to the superoxo complex 22+ at E0=0.11 V (vs. SCE) with a small inner sphere electron-transfer reorganization energy, λi=0.54 eV, determined from variable temperature electrochemical impedance spectroscopy. The data suggest that the O2.−/O22− redox process occurs directly on the O2-derived core. [ABSTRACT FROM AUTHOR]

Neuroglobin (Ngb) was the first vertebrate nerve globin to be identified. Since then, different physiological roles have been hypothesised for this hexa-coordinated globin, but its function is far from being unambiguously assigned. In a previous work, we collected first evidences of Ngb potentially taking part to electron transfer (ET) processesin vivo, investigating the redox thermodynamics of this globin. Here, we perform a computational investigation on the complex between Ngb and its putativein vivopartner cytcand on the ET process between the two species. The simulated structure of the complex is amenable for ET in terms of distance and relative protein orientation. Moreover, the redox-dependent stability of the predicted Ngb-cytcadduct and the very good agreement between calculated determinants to the ET rate and those of paradigmatic metalloproteins acting as electron shuttles all support a potential role of neuroglobin as an electron transfer species. [ABSTRACT FROM AUTHOR]

Proton-coupled electron transfer (PCET) at metal-oxide nanoparticle interfaces plays a critical role in many photocatalytic reactions and energy conversion processes. Recent experimental studies have shown that photoreduced ZnO nanocrystals react by PCET with organic hydrogen atom acceptors such as the nitroxyl radical TEMPO. Herein, the interfacial PCET rate constant is calculated in the framework of vibronically nonadiabatic PCET theory, which treats the electrons and transferring proton quantum mechanically. The input quantities to the PCET rate constant, including the electronic couplings, are calculated with density functional theory. The computed interfacial PCET rate constant is consistent with the experimentally measured value for this system, providing validation for this PCET theory. In this model, the electron transfers from the conduction band of the ZnO nanocrystal to TEMPO concertedly with proton transfer from a surface oxygen of the ZnO nanocrystal to the oxygen of TEMPO. Moreover, the proton tunneling at the interface is gated by the relatively low-frequency proton donor-acceptor motion between the TEMPO radical and the ZnO nanocrystal. The ZnO nanocrystal and TEMPO are found to contribute similar amounts to the inner-sphere reorganization energy, implicating structural reorganization at the nanocrystal surface. These fundamental mechanistic insights may guide the design of metal-oxide nanocatalysts for a wide range of energy conversion processes. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were performed to study the effect of shell encapsulation on the geometrical and electronic properties of pure and hybrid core-shell CdSe nanoclusters. The CdSe cores are distorted by the shells, and the shells exhibit distinct surface activity from the cores, which leads to remarkable changes in their electron transition behaviors. Although the electron and hole reorganization energies, which are related to the formation and recombination of electron-hole pairs, vary in a complicated way, their itemized contributions, potentials of electron extraction, ionization and affinity, and hole extraction ( HEP ), are dependent on the cluster size, shell composition and/or solvent. Our calculations suggest that the behaviors of charge carriers, free electrons and holes, in the semiconductor core-shell nanoclusters can be modulated by selecting appropriate cluster size and controlling the chemical composition of the shells. [ABSTRACT FROM AUTHOR]

Eight molecules with D-π-D molecular motifs coded HTM (1-4)a,b were designed as efficient symmetric hole transporting materials for perovskite solar cells. These HTMs are composed of different core moieties, such as spiro [fluorene-9,9′-xanthene]-diol (SFO), spiro [fluorene-9,9′-xanthene]-dimethoxy (SFM), benzo [c][1,2,5]thiadiazole (BTD), and biphenyl (BP) and are gaining lot of attention because of their low-cost, reproducible electrical and optical properties in device performance. Detailed information about the energetic of molecular levels (GSOP/ESOP), first singlet excitation energy (E 0-0), equilibrium molecular geometry, charge separation, charge transfer, reorganization energies, polarizability and hyperpolarizability, density of states (DOS), solubility and stability of these molecules was attained by systematically performing molecular modeling calculations using density functional theory (DFT) and time dependent-DFT calculations utilizing hybrid density functional B3LYP using the basis set 6–31g(d,p) level of theory as a successful method for predicting the photophysical and photovoltaic properties of these conjugated systems. The results showed that not only the core moieties, but also Schiff-base linkage extended conjugation, have an effect on the photophysical and photovoltaic properties of the proposed HTMs. It was demonstrated that HTMs incorporating SFO (HTM 1a,b), SFM (HTM 2a,b), and BP (HTM 4a,b) achieved better charge transport, high stability values (η a = 2.11–2.40 eV), low electron-hole binding energy (E b = 0.16–0.21 eV) than HTM 3a,b with BTD core, which improves hole mobility and decreases recombination, all of which improved device photocurrent, which can be attributed to the extended π-conjugation in SFO, SFM and BP cores. These findings are strikingly similar to those of Spiro-OMeTAD (η a = 2.45 eV, E b = 0.16 eV), indicating that these HTMs are promising candidates for efficient and cost-effective PSCs. Interestingly, when the stability of HTM (1-4)a and HTM (1-4)b was compared, it was clear that HTM (1-4)a has lower stability than HTM (1-4)b , which could be attributed to the presence of Schiff base C N bonds in HTM (1-4)b , which reduces the molecules stability when compared to HTM (1-4)b , owing to a strong C–C linkage. Meanwhile, HTM (1-4)a outperforms HTM (1-4)b in terms of electronic performance and hole mobility. Graphical abstract showing the schematic diagram of a fabricated perovskite solar cell based on HTM (1-4)a,b with various core structures and Spiro-OMeTAD. [Display omitted] • Novel hole transporting materials coded HTM (1-4)a,b were designed for commercialization of low-cost PSCs. • Structure optimization, GSOP/ESOP, charge density distribution and photovoltaics properties were predicted via DFT/TD-DFT calculations. • HTM (1,2,4)a,b achieved a comparable stability to the benchmark Spiro-OMeTAD. • The outstanding photophysical and optoelectronic properties of HTM (1-4)a,b making them a promising candidate for efficient, and cheap PSCs. [ABSTRACT FROM AUTHOR]

Neuroglobin (Ngb) is a recently identified hexa-coordinated globin, expressed in the nervous system of humans. Its physiological role is still debated: one hypothesis is that Ngb serves as an electron transfer (ET) species, possibly by reducing cytochrome c and preventing it to initiate the apoptotic cascade. Here, we use the perturbed matrix method (PMM), a mixed quantum mechanics/molecular dynamics approach, to investigate the redox thermodynamics of two neuroglobins, namely the human Ngb and GLB-6 from invertebrate Caenorhabditis elegans. In particular, we calculate the reduction potential of the two globins, resulting in an excellent agreement with the experimental values, and we predict the reorganization energies, λ, which have not been determined experimentally yet. The calculated λ values match well those reported for known ET proteins and thereby support a potential involvement in vivo of the two globins in ET processes. [ABSTRACT FROM AUTHOR]

A combination of experimental data and theoretical analysis provides evidence of a bell-shaped kinetics of electron transfer in the Arrhenius coordinates ln k vs 1/T. This kinetic law is a temperature analogue of the familiar Marcus bell-shaped dependence based on ln k vs the reaction free energy. These results were obtained for reactions of intramolecular charge shift between the donor and acceptor separated by a rigid spacer studied experimentally by Miller and co-workers. The non-Arrhenius kinetic law is a direct consequence of the solvent reorganization energy and reaction driving force changing approximately as hyperbolic functions with temperature. The reorganization energy decreases and the driving force increases when temperature is increased. The point of equality between them marks the maximum of the activationless reaction rate. Reaching the consistency between the kinetic and thermodynamic experimental data requires the non-Gaussian statistics of the donor-acceptor energy gap described by the Q-model of electron transfer. The theoretical formalism combines the vibrational envelope of quantum vibronic transitions with the Q-model describing the classical component of the Franck-Condon factor and a microscopic solvation model of the solvent reorganization energy and the reaction free energy. [ABSTRACT FROM AUTHOR]

Six donor-acceptor systems with styrene based 9-phenyl carbazole, 4,4’-di(hydro, methyl, methoxy or octyloxy) triphenylamine and 4-methylphenyl indoline derivatives as donors, and s-triazine group as the acceptor were synthesized and characterized. The charge-separated states of these donor-acceptor systems were generated through the effective photoinduced electron transfers from excited donor modules to acceptor modules and had lifetimes ranging from 57 ns to 215 ns. These donor-acceptor systems are capable of fast charge separation, but have extremely slow charge recombination. The back electron transfer processes of these donor-acceptor systems occur in the inverted region of the Marcus curve. The driving forces of back electron transfer and the reorganization energies of electron transfer decrease in the order of 9-phenyl carbazole derivative, 4,4’-di(hydro, methyl, methoxy or octyloxy) triphenylamine derivative and 4-methylphenyl indoline derivative. These two factors work together to determine the different lifetimes of charge-separated states in these donor-acceptor systems. [ABSTRACT FROM AUTHOR]

Electron transfer rate constant decreases gradually for a Fe 2+/3+ redox system as platinum deposition covers a gold surface. This effect is assumed to be conditioned by reconstruction of double electric layer on a platinum deposit which increases reorganization energy and decreases the redox reaction rate constant. [ABSTRACT FROM AUTHOR]

Peptidylglycine a-hydroxylating monooxygenase (PHM) and dopamine β-monooxygenase (DβM) are copper-dependent enzymes that are vital for neurotransmitter regulation and hormone biosynthesis. These enzymes feature a unique active site consisting of two spatially separated (by 11 Å in PHM) and magnetically noncoupled copper centers that enables 1e- activation of O2 for hydrogen atom abstraction (HAA) of substrate C-H bonds and subsequent hydroxylation. Although the structures of the resting enzymes are known, details of the hydroxylation mechanism and timing of long-range electron transfer (ET) are not clear. This study presents density-functional calculations of the full reaction coordinate, which demonstrate: (i) the importance of the end-on coordination of superoxide to Cu for HAA along the triplet spin surface; (ii) substrate radical rebound to a CuII hydroperoxide favors the proximal, nonprotonated oxygen; and (iii) long-range ET can only occur at a late step with a large driving force, which serves to inhibit deleterious Fenton chemistry. The large inner-sphere reorganization energy at the ET site is used as a control mechanism to arrest premature ET and dictate the correct timing of ET. [ABSTRACT FROM AUTHOR]

Poly(3-hexylthiophene) (P3HT) is a common material used as electron donor element in active layers of organic solar cells. Previous studies have shown that is possible to improve the electronic properties of the P3HT through chemical substitutions in the empty beta-position of the thiophene rings; however, up to now it was not reported the effect of chemical substitutions in the charge transport properties of the P3HT. In this work we theoretically investigate the reorganization energy related to the transport of holes and electrons of P3HT and 19 derivatives, employing a combination of density functional theory to calculate the electronic structure and a semiempirical method to optimize the geometry. Our results show that the chemical substitutions are able to improve the charge carrier transfer rate, but certain substituents tend to favour a greater transport of electrons than holes, which is not desirable for polymeric electron donor materials. [ABSTRACT FROM AUTHOR]

The Marcus theory of electron transfer predicts a bell-shaped dependence of the reaction rate on the reaction free energy. The top of the "inverted parabola" corresponds to zero activation barrier when the electron-transfer reorganization energy and the reaction free energy add up to zero. Although this point has traditionally been reached by altering the chemical structures of donors and acceptors, the theory suggests that it can also be reached by varying other parameters of the system including temperature. We find here dramatic evidence of this phenomenon from experiments on a fullerene--porphyrin dyad. Following photoinduced electron transfer, the rate of charge recombination shows a bell-shaped dependence on the inverse temperature, first increasing with cooling and then decreasing at still lower temperatures. This non-Arrhenius rate law is a result of a strong, approximately hyperbolic temperature variation of the reorganization energy and the reaction free energy. Our results provide potentially the cleanest confirmation of the Marcus energy gap law so far since no modification of the chemical structure is involved. [ABSTRACT FROM AUTHOR]

Using statistical-field techniques, we develop a molecular-based dipolar self-consistent-field theory (DSCFT) for charge solvation in liquid mixtures under equilibrium and nonequilibrium conditions, and apply it to compute the solvent reorganization energy of electron-transfer reactions. In addition to the nonequilibrium orientational polarization, the reorganization energy in liquid mixtures is also determined by the out-of-equilibrium solvent composition around the reacting species due to preferential solvation. Using molecular parameters that are readily available, the DSCFT naturally accounts for the dielectric saturation effect and the spatially varying solvent composition in the vicinity of the reacting species. We identify three general categories of binary solvent mixtures, classified by the relative optical and static dielectric permittivities of the solvent components. Each category of mixture is shown to produce a characteristic local solvent composition profile in the vicinity of the reacting species, which gives rise to the distinctive composition dependence of the reorganization energy that cannot be predicted using the dielectric permittivities of the homogeneous solvent mixtures. [ABSTRACT FROM AUTHOR]

Electron transfer (ET) is the key process in light-driven charge separation reactions in organic solar cells. The current review summarizes the progress in theoretical modelling of ET in these materials. First we give an account of ET, with a description originating from Marcus theory. We systematically go through all the relevant parameters and show how they depend on different material properties, and discuss the consequences such dependencies have for the performance of the devices. Finally, we present a set of visualization methods which have proven to be very useful in analyzing the elementary processes in absorption and charge separation events. Such visualization tools help us to understand the properties of the photochemical and photobiological systems in solar cells. [ABSTRACT FROM AUTHOR]

Some general characteristics of the rate constant of the non-adiabatic heterogeneous electron transfer are considered and the ways of the extensions of the Marcus approximation are studied. A number of the approximate formulas suggested earlier for the rate constant are examined critically with the emphasis on that obtained by Y. Zeng et al. [J. Electroanal. Chem. 735 (2014) 77–83]. We suggest the more accurate analytical formulas for the rate constant which can have applications in the practical calculations because they also permit avoiding the calculation of the improper integral over the Fermi distribution function. These approximate formulas are based on the integration by parts of the improper integral in the explicit expression for the rate constant without the use of any asymptotic matching and have ≤ 1% error for all reaction free energies and realistic reorganization energies. [ABSTRACT FROM AUTHOR]

We employed single-particle photoluminescence (PL) measurements to investigate the interfacial electron transfer between single Au nanorods (NRs) and TiO2 coated by ALD. Analyzing the energy relaxation path of plasmon-generated hot electrons as well as the PL intensities allowed for the detection and study of the interfacial electron transfer process spatially. [ABSTRACT FROM AUTHOR]