Intramolecular Electron Transfer Reactions Research Articles

Simulating Cavity-Modified Electron Transfer Dynamics on NISQ Computers.

We present an algorithm based on the quantum-mechanically exact tensor-train thermo-field dynamics (TT-TFD) method for simulating cavity-modified electron transfer dynamics on noisy intermediate-scale quantum (NISQ) computers. The utility and accuracy of the proposed methodology is demonstrated on a model for the photoinduced intramolecular electron transfer reaction within the carotenoid-porphyrin-C60 molecular triad in tetrahydrofuran (THF) solution. The electron transfer rate is found to increase significantly with increasing coupling strength between the molecular system and the cavity. The rate process is also seen to shift from overdamped monotonic decay to under-damped oscillatory dynamics. The electron transfer rate is seen to be highly sensitive to the cavity frequency, with the emergence of a resonance cavity frequency for which the effect of coupling to the cavity is maximal. Finally, an implementation of the algorithm on the IBM Osaka quantum computer is used to demonstrate how TT-TFD-based electron transfer dynamics can be simulated accurately on NISQ computers.

Acridinedione-phthalimide conjugates: Intramolecular electron transfer and singlet oxygen generation studies for optical and photodynamic therapy applications

We reported herein the synthesis, characterization of hybrid conjugates composed of phthalimide (Phth) and acridine-1,8-diones (Acr) for optical and medical applications. For the synthetic procedure, a three-step synthetic strategy has been utilized. The optical properties of the examined 1,8-acridinedione–phthalimide connected molecules (AcrPhth 1–5) have been examined utilizing various spectroscopic techniques, e.g., steady-state absorption and fluorescence, and time-correlated single photon counting. The steady-state absorption studies showed that AcrPhth 1–5 absorbs the light in the UV and visible region. The fluorescence studies of AcrPhth 1–5 exhibited significant fluorescence quenching compared to the acridinedione control compounds (Acr 1–5) suggesting the occurrence of electron-transfer reactions from the electron donating acridinedione moiety (Acr) to the electron accepting phthalimide moiety (Phth). The rate and efficiency of the electron-transfer reactions were determined from the fluorescence lifetime measurements indicating the fast electron-transfer processes of the covalently connected AcrPhth 1–5 conjugates. Computational studies supported the intramolecular electron-transfer reaction of AcrPhth conjugates using ab initio B3LYP/6-311G methods. In the optimized structures, the HOMO was found to be entirely located on the Acr entity, while the LUMO was found to be entirely on the Phth entity. Further, the synthesized compounds were tested as photosensitizers for generating the singlet oxygen species, which is a key factor in the photodynamic therapy (PDT) applications. The nanosecond laser flash measurements enable us to detect the triplet-excited states of examined Acr and AcrPhth conjugates, determining the triplet quantum yields, and direct detecting the singlet oxygen in an accurate way. From this observation, the singlet quantum yields were found to be in the range of 0.12–0.27 (for Acr 1–5) and 0.07–0.19 (for AcrPhth 1–5 conjugates). The molecular docking studies revealed that compound AcrPhth 2 exhibited high binding affinity with for key genes (p53, TOP2B, p38, and EGFR) suggesting its potential as a targeted anticancer therapy.Graphical abstractEfficient intramolecular electron-transfer reaction for the light harvesting conjugates! In addition, the conjugates can be used as good photosensitizers for PDT

Entropy-Enthalpy Compensation in Electron-Transfer Processes.

Solvent reorganization energies, free energies, and entropies are obtained for photoexcitation of three molecules that exhibit strong solvatochromism [Nile red, 5-(dimethylamino)-5'-nitro-2,2-bisthiophene, and Reichardt's dye B30] by measuring their optical absorption spectra at temperatures between 150 and 300 K in solvents with a range of polarities. Energies, free energies, and entropies of solvent reorganization are also obtained from computer simulations of three intramolecular electron-transfer reactions (charge separation and recombination in Zn-porphyrin-quinone cyclophane and charge transfer in a bis-biphenylandrostane radical anion). Entropy-enthalpy compensation in the solvent reorganization free energy for photoexcitation or electron transfer is found to be essentially complete (having nearly equal and opposite contributions from entropic and enthalpic effects) for all of the processes with solvent reorganization energies less than about 0.1 eV. Compensation becomes less complete as the reorganization energy becomes larger. A semiclassical treatment of the solvent reorganization entropy can rationalize these results.

Exploring the effect of a pendent amine group poised over the secondary coordination sphere of a cobalt complex on the electrocatalytic hydrogen evolution reaction.

A CoIII complex (2) of a bispyridine-dioxime ligand (H2LNMe2) containing a tertiary amine group in the proximity of the Co center is synthesized and characterized. One of the oxime protons of the ligand is deprotonated, and the amine group remains protonated in the solid-state structure of the CoII complex (2a). The acid-base properties of 2 showed pKa values of 5.9, 8.4, and 9.6, which are assigned to the dissociation of two consecutive oxime protons and amine protons, respectively. The electrocatalytic proton reduction of 2 was investigated in an aqueous phosphate buffer solution (PBS), revealing a catalytic hydrogen evolution reaction (HER) at an Ecat/2 of -1.01 V vs. the SHE, with an overpotential of 673 mV and a kobs value of 2.6 × 103 s-1 at pH 7. For comparison, the HER of the Co complex (1) lacking the tert-amine group at the secondary sphere was investigated in PBS, which showed a kobs of 1.3 × 103 s-1 and an overpotential of 577 mV. At pH 4, however, 2 revealed a ∼3 times higher kobs value than 1, which suggests that the protonated amine group likely works as a proton relay site. Notably, no significant change in the reaction rate was observed at different pH values for 1, implying that oxime protons may not be involved in the intramolecular proton-coupled electron transfer reaction in the HER. The kobs values for Co complexes at pH 7.0 are significantly higher than those of the [Co(dmgH)2(pyridine)(Cl)] complex, implying that the primary coordination sphere around 1 or 2 enhances the HER and offers better catalyst stability in acidic buffer solutions.

Boosting Photon Emission from the Chemiluminescence of Luminol Based on Host-Guest Recognition for the Determination of Dopamine.

Modulating the photon emission of the luminophore for boosting chemiluminescence (CL) response is very crucial for the construction of highly sensitive sensors via the introduction of functionalized materials. Herein, the integration of the emitter and coreactant accelerator into one entity is realized by simply assembling cucurbit[7]uril (CB[7]) on the surface of gold nanoparticles (AuNPs) through simple assembly via a Au-O bond. The loaded CB[7] on the AuNPs improves their catalytic capacity for the generation of hydroxyl radicals(•OH). Moreover, the host-guest recognition interaction between luminol and CB[7] enables the capture of luminol on AuNPs efficiently. Also, the intramolecular electron-transfer reaction between the luminol and •OH enables the CL response more effectively in the entity, which greatly boosts photon emission ca 100 folds compared with the individual luminol/H2O2. The host-guest recognition between luminol and CB[7] is revealed by Fourier transform infrared spectroscopy, electrochemical, and thermogravimetric characterization. Moreover, the proposed CL system is successfully used for the sensitive and selective determination of dopamine (DA) based on a synergistic quenching mechanism including the competition quenching and radical-scavenging effect from DA. The present amplified strategy by integrating recognized and amplified elements within one entity simplifies the sensing process and holds great potential for sensitive analysis based on the self-enhanced strategies.

An electrochlorination process integrating enhanced oxidation of phosphonate to orthophosphate and elimination: Verification of matrix chloridion-induced oxidation mechanism

Phosphonate used as scale inhibitor is a non-negligible eutrophic contaminant in corresponding polluted waters. Besides, its conversion to orthophosphate (ortho-P) is a precondition for realizing bioavailable phosphorus recovery. Due to the feeble degradation efficiency with less than 30 % from classical Fenton commonly used in industrial wastewater treatment and itself vulnerable to strong inhibition interference of matrix chloride ions, we proposed an electrochemical approach to transform the native salt in the solution into oxidizing substances, sort of achieving beneficial utilization of matrix waste, and enhanced the ortho-P conversion rate of 1-Hydroxyethane-1,1-diphosphonic acid (HEDP) to 89.2 % (± 3.6 %). In electrochlorination system, it was found that HEDP rapidly complexed with Fe(II) and then coordinated in-situ Fe(III) to release free HEDP via intramolecular metal-ligand electron transfer reaction. The subsequent degradation mainly rooted in the oxidation of pivotal reactive species HClO, FeIVO2+ and 1O2, causing C-P and CC bonds to fracture in sequence. Eventually the organically bound phosphorus of HEDP was recovered as ortho-P. This study acquainted the audiences with the rare mechanism of chloridion-triggered HEDP degradation under electrochemical way, as well as offered a feasible technology for synchronous transformation of organically bound phosphorus to ortho-P and elimination from phosphonates.

Intramolecular Photoinduced Energy and Electron Transfer Reactions in Phenanthroimidazole-Boron Dipyromethane Donor-Acceptor Dyads.

Donor-acceptor systems in which a donor phenanthroimidazole (PhI) is directly connected to a BODIPY acceptor (Dyad1) and separated by an ethynyl bridge between PhI and BODIPY (Dyad2) have been designed, synthesized, and characterized by various spectroscopic and electrochemical techniques. Optical absorption and 1H NMR characteristics of both dyads with those of constituent individuals suggest that there exists a minimum π-π interaction between phenanthroimidazole and BODIPY. Quenched emission of both the dyads was observed when excited either at phenthaoimidazole absorption maxima or at BODIPY absorption maxima in all three investigated solvents. The detailed spectral analysis provided evidence for an intramolecular photoinduced excitation energy transfer (PEnT) from the singlet excited state of phenanthroimidazole to BODIPY and photoinduced electron transfer (PET) from the ground state of phenanthroimidazole to BODIPY. Transient absorption studies suggest that charge-separated species (PhI•+ - BODIPY•-) are generated at a rate constant of (1.16 ± 0.01) × 108 s-1 for the dyads Dyad1 and (5.15 ± 0.03) × 108 s-1 and for Dyad2 whereas energy transfer rate constants were much higher and were on the order of (1.1 ± 0.02) × 1010 s-1 and (1.6 ± 0.02) × 1010 s-1 for Dyad1 and Dyad2, respectively, signifying their usefulness in light energy harvesting applications.

Full theoretical protocol for the design of metal-free organic electron donor-spacer-acceptor systems.

A user-friendly (time-dependent) density functional theory based algorithm is proposed to design new donor-spacer-acceptor systems for electron transfer reactions. This algorithm is focused on metal-free organic compounds, most of which contain aromatic or alkene moieties. The oxidation and reduction potentials are calculated, together with the excited-state energy difference including the zero-point energy and the structural properties required to calculate an electron transfer Gibbs free energy change. The proposed algorithm has been tested on well-known systems, while two new compounds are suggested for photoinduced intramolecular electron transfer reactions using this scheme. The methodology here presented is intended to be a tool for synthetic physical-chemists, allowing them to evaluate the properties of hypothetical systems before the synthesis, enabling the study of limitless combinations of donor-spacer-acceptor arrangements.

Electron Transfer Rates in Polar and Non-Polar Environments: a Generalization of Marcus' Theory to Include an Effective Treatment of Tunneling Effects.

A multistep kinetic model in which solvent motion is treated in the framework of Marcus theory and the rates of the elementary electron transfer step are evaluated at full quantum mechanical level is proposed and applied to the calculation of the rates of intramolecular electron transfer reactions in rigidly spaced D–Br–A (D = 1,1′-biphenyl radical anion, Br = androstane) compounds, for five acceptors (A) in three organic solvents with different polarity. The calculated rates agree well with experimental ones, and their temperature dependence is almost quantitatively reproduced.

Site-Differentiated Iron-Sulfur Cluster Ligation Affects Flavin-Based Electron Bifurcation Activity.

Electron bifurcation is an elegant mechanism of biological energy conversion that effectively couples three different physiologically relevant substrates. As such, enzymes that perform this function often play critical roles in modulating cellular redox metabolism. One such enzyme is NADH-dependent reduced-ferredoxin: NADP+ oxidoreductase (NfnSL), which couples the thermodynamically favorable reduction of NAD+ to drive the unfavorable reduction of ferredoxin from NADPH. The interaction of NfnSL with its substrates is constrained to strict stoichiometric conditions, which ensures minimal energy losses from non-productive intramolecular electron transfer reactions. However, the determinants for this are not well understood. One curious feature of NfnSL is that both initial acceptors of bifurcated electrons are unique iron–sulfur (FeS) clusters containing one non-cysteinyl ligand each. The biochemical impact and mechanistic roles of site-differentiated FeS ligands are enigmatic, despite their incidence in many redox active enzymes. Herein, we describe the biochemical study of wild-type NfnSL and a variant in which one of the site-differentiated ligands has been replaced with a cysteine. Results of dye-based steady-state kinetics experiments, substrate-binding measurements, biochemical activity assays, and assessments of electron distribution across the enzyme indicate that this site-differentiated ligand in NfnSL plays a role in maintaining fidelity of the coordinated reactions performed by the two electron transfer pathways. Given the commonality of these cofactors, our findings have broad implications beyond electron bifurcation and mechanistic biochemistry and may inform on means of modulating the redox balance of the cell for targeted metabolic engineering approaches.

Intramolecular photoinduced electron transfer reactions of zinc(II) porphyrin dyads studied with a sub-ns time resolution

We report the dynamics of a intramolecular photoinduced electron transfer reaction of Zn(II)-porphyrin dyads that have a 2,2[Formula: see text]-bipyridine moiety at the periphery in the presence of Cu[Formula: see text] in methanol studied using laser flash photolysis with a sub-nanosecond time resolution. The photoinduced electron transfer reactions were observed from the excited [Formula: see text] and [Formula: see text] states of the Zn(II)-porphyrin to the Cu(II)-2,2[Formula: see text]-bipyridine moiety, and the structural dependence of the reactivity were discussed in terms of the distance between the electron donating and accepting centers.

Self-Enhanced Chemiluminescence of Tris(bipyridine) Ruthenium(II) Derivative Nanohybrids: Mechanism Insight and Application for Sensitive Silver Ions Detection.

In recent years, self-enhanced tris(bipyridine) ruthenium(II)-based luminescence systems have achieved great development in electrochemiluminescence (ECL) but are seldom mentioned in chemiluminescence (CL). Herein, a self-enhanced CL luminophore with excellent CL behavior was synthesized by covalently cross-linking tris(4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) dichloride ([Ru(dcbpy)3]Cl2) with branched polyethylenimine (BPEI) in one molecule (BPEI-Ru(II)), which then self-assembled into nanoparticles (BRuNPs). The nanoparticles exhibited stable and strong CL emission with potassium persulfate (K2S2O8) as the oxidant. After the redox reaction between K2S2O8 and BRuNPs, and the subsequent intramolecular electron-transfer reaction, excited state luminophores were generated to emit light. This self-enhanced CL system shortened the electron transfer distance and reduced energy loss, thus improving the luminous efficiency. In addition, the CL lifetime of BRuNPs/K2S2O8 was longer than classical luminophores such as N-(4-aminobutyl)-N-ethylisoluminol (ABEI), indicating the potential application of this system in CL imaging. Surprisingly, Ag+ was found to greatly improve the CL efficiency of BRuNPs/K2S2O8 by catalyzing the decomposition of K2S2O8 to generate SO4•-. On the basis of the enhancement effect of Ag+, a simple and rapid CL method was proposed for Ag+ detection. The chemosensor showed a wide linear range from 25 to 3000 nM and low detection limit of 9.03 nM, as well as good stability and excellent selectivity. More importantly, this result indicated that Ag+ can be used as a coreaction accelerator to develop a ternary self-enhanced CL system, BRuNPs/K2S2O8/Ag+.

Solvation heterogeneity in ionic liquids as demonstrated by photo-chemical reactions

Abstract It has been recognised that ionic liquids (ILs) with long alkyl-chains have a segregated structure due to the inhomogeneous distribution of polar parts and non-polar parts. This inhomogeneity of ILs brings about unique solvation phenomena of solute molecules dissolved in ILs. We have investigated various solvation-state selective phenomena by using laser spectroscopic techniques such as solvation state selective vibrational spectroscopy, translational and rotational dynamics of small molecules in ILs, and solvation state selective fundamental chemical reactions. In this paper, we have reviewed an intramolecular electron transfer (ET) reaction in the Marcus inverted region of N,N-dimethyl-p-nitroaniline and an intramolecular proton transfer (IPT) reaction in 4′-N,N-diethylamino-3-hydroxyflavone as examples of chemical reactions affected by unique solvation in ILs.

The conventional turns rather than irregular γ-/β-turn secondary structures accounting for the antitumor activities of cyclic peptide Phakellistatin 6 analogs

Cyclic peptides has become an attractive modality for drug development due to their excellent binding affinity, target selectivity and low toxicity, however significant activity difference between the synthetic and natural cyclic peptides such as Phakillestatins has puzzled chemists for years. In an effort to explore the bioactive secondary structures, three pairs of cyclic Phakellistatin 6 analogs with special constrained stereo-features were prepared by regioselectively controlled intramolecular photoinduced single electron transfer (SET) reactions in this paper. The spatial configurationally features were systematically investigated by ECD and NMR, together with detailed structural analysis based on theoretical calculations, which showed that conventional turns rather than irregular γ-/β-turn secondary structures played important roles for the antitumor activities. We also presented the in vitro bioactive assay, liposomal leakage assays and electron microscopy analyses, which indicated the prepared cyclopeptide analogs excellent antitumor activities, most showing greater growth inhibitory effects than that of the famous anticancer agent paclitaxel.

Photocatalytic hydrogen production from acidic aqueous solution in BODIPY-cobaloxime-ascorbic acid homogeneous system

Iodinated boron dipyrromethene (BODIPY) dyes with 8-hydroxyl-quinoline or phenylamine moiety at the meso-position on the BODIPY core were used as efficient photosensitizers (PSs) of three-component light-driven production of H2 system from acidic aqueous solution in conjunction with a cobaloxime [CoIII(dmgH)2PyCl] (dmgH=dimethylglyoximate, and py=pyridine) as proton-reducing catalyst and ascorbic acid (H2A) as sacrificial electron donor. This is the first example of BODIPYs as homogeneous hydrogen-generating PSs employed in the acidic aqueous conditions. That they are active in the acidic solutions and inactive in the basic conditions may indicate that the extent of competition between intramolecular and intermolecular electron transfer reactions exists. Efficient bimolecular electron transfer reaction between PS and molecular catalyst is needed to make H2 production, while the intramolecular electron transfer of PS may curb H2 production. The results underscore that the chemical modification of BODIPYs can be performed, thus allowing for the transformation of acid and base conditions for the light-driven H2 production.

Kinetics and Mechanism of the Autocatalytic Oxidation of Bis(terpyridine)iron(II) by Peroxomonosulfate Ion (Oxone) in Acidic Medium.

The autocatalytic oxidation of the bis(terpyridine)iron(II) complex, Fe(tpy)22+ by peroxomonosulfate ion (PMS) proceeds via the formation of the corresponding iron(III) complex (Fe(tpy)23+) as the primary oxidation product. The proton-assisted dissociation of Fe(tpy)22+ and subsequent oxidation of Fe2+ are side reactions in this system. In the initial stage of the reaction, a 1:1 adduct is formed between PMS and bis(terpyridine)iron(II), which decomposes in an intramolecular electron transfer reaction step. The autocatalytic role of Fe(tpy)23+ was also confirmed in the overall process. This effect is interpreted by considering the formation of an additional adduct between PMS and Fe(tpy)23+. The decomposition of the adduct yields two strong oxidizing intermediates, an Fe(IV) species and SO4-•, which consume the iron(II) complex in rapid reaction steps. A detailed kinetic model was postulated for the overall oxidation of Fe(tpy)22+ by PMS. The equilibrium constants for the formation of the adducts between PMS and complexes Fe(tpy)22+ and Fe(tpy)23+ were estimated as 129 ± 18 M-1 and 87 ± 10 M-1, respectively. In contrast to the closely related Fe(phen)32+-PMS reaction, the N-oxide derivative of the ligand (tpyO) does not have any kinetic role in the overall process because of the very slow formation of the N-oxide in the reaction.

Efficient Constrained Density Functional Theory Implementation for Simulation of Condensed Phase Electron Transfer Reactions.

Constrained density functional theory (CDFT) is a versatile tool for probing the kinetics of electron transfer (ET) reactions. In this work, we present a well-scaling parallel CDFT implementation relying on a mixed basis set of Gaussian functions and plane waves, which has been specifically tailored to investigate condensed phase ET reactions using an explicit, quantum chemical representation of the solvent. The accuracy of our implementation is validated against previous theoretical results for predicting electronic couplings and charge transfer energies. Subsequently, we demonstrate the efficiency of our method by studying the intramolecular ET reaction of an organic mixed-valence compound in water using a CDFT based molecular dynamics simulation.

Structure dependence of intramolecular electron transfer reactions of simple dyads of a zinc(ii) porphyrin complex bearing a peripheral bipyridine moiety.

New dyad systems based on a zinc(ii) porphyrin complex and a 2,2'-bipyridine moiety linked by amide bridges having various bridging groups were synthesized. The photochemical behavior was investigated using fluorescence spectroscopy and a time-resolved absorption technique. The singlet excited state of the porphyrin complex was found to be partially quenched by Cu2+ in methanol, and a photoinduced electron transfer from the excited state of the porphyrin moiety to the Cu(ii)-bipyridine moiety was observed using a transient absorption technique. The relatively long lifetime of the charge-separated state was ascribed to the slow electron-transfer reaction of the Cu(ii)/Cu(i) couple bound to the bipyridine moiety. The lifetime of the charge-separated state of dyads becomes longer with the increase of the distance between the porphyrin and bipyridine moieties, and these findings are discussed using an empirical formula for the relationship between the reactivity and molecular structure of dyads.

Electrospray ionization in the study of the interactions between cytotoxic phosphino Cu(I) complexes and selected amino acids and GlyGlyHis peptide model.

Tetrahedral [Cu(P)4][BF4]-type complexes (P = tertiary phosphine) are a class of monopositively charged compounds that have shown notable antitumor activity in both in vitro and in vivo tests. This biological property appears to be related to the peculiar physicochemical characteristics of these compounds. Although thermodynamically stable, they are labile at micromolar concentrations. Such a behavior allows the Cu(I) ion in [Cu(P)n]+ assemblies (n < 4) to interact with surrounding molecules, including the rich peptide/protein environment that metal complexes have to face in the physiological milieu on the way to tumor cells. The scope of this investigation was to study the interaction products that originate from the treatment in water/methanol mixtures of representative phosphino Cu(I) compounds with an excess of individual amino acids (AAs) selected on the basis of the donor atom likely involved in metal coordination (i.e. O-glycine, S-methionine and N-histidine). These interactions have been investigated in electrospray ionization mass spectrometry (ESI-MS), mainly in the positive ion mode [ESI(+)MS], and the interaction products have been characterized by sequential collisional experiments, performed by an ion trap instrument. Histidine and methionine, but not glycine, were able to mine Cu(I) from [Cu(P)n]+ assemblies through the formation of mixed [CuI(P)(AA)]+ and eventually [CuI(AA)2]+ adducts. The ability to substitute phosphine(s) by AAs and the strongest affinity for Cu(I) was proved by the study of the energetics of collisional-induced decomposition (CID) reactions [CuI(P)(AA)]+ → CuI(AA) + P]+. Among the investigated AAs, histidine displayed the strongest affinity for Cu(I). Transchelation of Cu(I) was similarly observed when [Cu(P)n]+ species were treated with the model tripeptide GlyGlyHis (GGH), the most investigated member of the amino terminal Cu(II) and Ni(II) (ATCUN) peptide family. GGH was able to form robust metal adducts not only with Cu(II) and the related divalent Zn(II) and Ni(II) ions, but also with monovalent ions, including Cu(I) and Ag(I). CID pathways of [CuI(GGH)]+ and [AgI(GGH)]+ were qualitatively superimposable and proceeded through losses of neutral fragments. Similar losses of neutral fragments were observed from [ZnII(GGH)] and [NiII(GGH)]. CID pathways of [CuII(GGH)]-/+ adducts instead took place mainly through intramolecular electron-transfer reactions comprising the reduction of Cu(II) to Cu(I) and the formation of fragment radical cations.

Dramatically enhanced aerobic Cr(VI) reduction with scrap zero-valent aluminum induced by oxalate

Abstract In the present study, the flexibility of utilizing scrap zero-valent aluminum (SZVAl) for Cr(VI) reduction mediated by oxalate was evaluated. Results show that the produced H 2 O 2 and the reactive electrons releasing from metal aluminum were the primary electron donors for the preferable Cr(VI) reduction in anaerobic SZVAl/Cr(VI)/oxalate system. The reduction rate of Cr(VI) decreased with the increase of both initial pH value of 1.5–4.5 and Cr(VI) initial concentration of 50–300 μM, increased with oxalate concentration from 0 to 4.0 mM, and markedly retarded under anaerobic condition due to the completely inhibited H 2 O 2 production. Notably, the accelerated Cr(VI) reduction induced by oxalate can be ascribed to the fact that the affinity of oxalate to Cr(VI)/Cr(V) species resulted in the expansion of Cr(VI)/Cr(V) coordination from tetrahedron to hexahedron, which was preferred for hexahedral Cr(III) species. Consequently, the presence of oxalate can significantly accelerate Cr(VI) reduction rate, and acted as an alternative electron donor simultaneously for Cr(VI) reduction through intramolecular electron transfer reaction. As compared with zero-valent aluminum (ZVAl), SZVAl exhibited superior reducing capacity for Cr(VI) reduction due to the presence of numerous galvanic cells in SZVAl corrosion process. The appreciable treatment efficiency of real chrome electroplating effluent indicates SZVAl/oxalate system presents as a preferable case of “waste control by waste” strategy. Moreover, the present study provided a new perspective on the role of oxalate in Cr(VI) reduction, which was significant in the detoxification of Cr(VI) process.