Metathesis Reaction Research Articles

Acyclic Boryl Complexes of Copper(I).

Reaction of (6-Dipp)CuOtBu (6-Dipp=C{NDippCH2 }2 CH2 , Dipp=2,6-iPr2 C6 H3 ) with B2 (OMe)4 provided access to (6-Dipp)CuB(OMe)2 via σ-bond metathesis. (6-Dipp)CuB(OMe)2 was characterised by NMR spectroscopy and X-ray crystallography and shown to be a monomeric acyclic boryl of copper. (6-Dipp)CuB(OMe)2 reacted with ethylene and diphenylacetylene to provide insertion compounds into the Cu-B bond which were characterised by NMR spectroscopy in both cases and X-ray crystallography in the latter. It was also competent in the rapid catalytic deoxygenation of CO2 in the presence of excess B2 (OMe)4 . Alongside π-insertion, (6-Dipp)CuB(OMe)2 reacted with LiNMe2 to provide a salt metathesis reaction at boron, giving (6-Dipp)CuB(OMe)NMe2 , a second monomeric acyclic boryl, which also cuproborated diphenylacetylene. Computational interrogation validated these acyclic boryl species to be electronically similar to (6-Dipp)CuBpin.

Versatility of a diamidosilylether ligand supporting yttrium complexes: Synthesis, structure and reactivity

Yttrium alkyl complex [NONDippY(CH2SiMe3)(THF)], 1 (NONDipp = (DippNSiMe2)2O, Dipp = 2,6-iPr-C6H3) can be prepared in high yields by a σ-bond metathesis reaction between [Y(CH2SiMe3)3(THF)2] and the free bis(aminosilyl)ether. The reaction of 1 with one equivalent of PhSiH3 generates the hydride bridged yttrium dimer [μ-NONDippY(μ-H)(THF)]22, however, each diamidosilylether ligand does not chelate each yttrium centre but instead bridges to both yttrium atoms in a “flyover” fashion. This ligand rearrangement maybe reversed by the addition of a strong Lewis base to give the dimeric yttrium hydride [NONDippY(μ-H)(DMAP)]23, where each diamidosilylether ligand now chelate to each yttrium center respectively. The effect of the different diamidosilylether bonding modes on the reactivity of the yttrium complexes is examined with heterocumulenes.

A double decomposition based coevolutionary algorithm for distributed multi-objective OPF solution

Due to the vast and complex nature of the power systems, the study of distributed solution to multi-objective OPF (MO-OPF) problem is vital. However, the existing distributed MO-OPF approaches are based on mathematical programming techniques. The tedious repetition of algorithmic executions is inevitable. Moreover, they can hardly solve the non-differential problem. In this paper, the coevolutionary multi-objective evolutionary algorithm (MOEA), combining the idea of decomposition, is introduced to solve the distributed MO-OPF problem. The decomposition first occurs on decision variables. After segmenting, multiple subpopulations can coevolve in a distributed manner under the support of a new proposed distributed fitness evaluation method. Further, an objective decomposition (OBD) method is applied to the proposed distributed MO-OPF approach. The problem is decomposed again based on objective functions. By this OBD method, the fitness assignment problem is effectively alleviated and a more extensively covered pareto front can be obtained. The experimental results on two systems of different scales first show the effectiveness of the proposed distributed approach and then demonstrate the excellence of the OBD method in large-scale system.

Analysis of Perioperative Factor Replacement Therapy for Hemophilia

Background Hemophilia is a hereditary bleeding disorder, especially in severe hemophilia, that can lead to spontaneous bleeding. For hemophilia patients with inhibitors, even minor acute bleeding events or surgical procedures can have catastrophic consequences. Some hemophiliacs are forced to make surgical choices. There are many risks in perioperative period when hemophiliacs undergo major surgery. Seeking effective and safe perioperative clotting factor replacement therapy or bypass therapy is the basis of successful surgery. Aims To seek effective and safe perioperative coagulation factor replacement therapy or bypass therapy. Methods HA patients were treated with FVIII preparation during perioperative period. To calculate dosage, multiply the patient ' s weight in kilograms by the FVIII level in IU/dL desired, then multiply by 0.5. Example: 50 kg × 40 (IU/dL level desired) × 0.5 = 1000 IU of FVIII. HB patients were treated with PCC or FIX during perioperative period. To calculate dosage, multiply the patient ' s weight in kilograms by the FIX level in IU/dL desired. Example: 50 kg body weight × 40 (IU/dL level desired) = 2000 IU of plasma-derived FIX. For hemophilia patients with low titer inhibitors, estimate the amount of FVIII required as a neutralizing inhibitor loading dose as recommended by WFH. The following formula is used to estimate the amount of FVIII needed as a loading dose to neutralize the inhibitor: [body weight (kg) × 80 × [(1 − hematocrit) × antibody titer (BU)]. An additional 50 IU/kg above the calculated loading dose is added to achieve a measurable FVIII activity. Patients with hemophilia combined with high titer inhibitors were treated with rFVIIa combined with PCC SCBT regimen. Sequential use refers to alternating rFVIIa and aPCC every 3 hours. Results 69 patients with indications for surgery and/or desire for surgery who underwent different types of surgery with clotting factor replacement therapy or bypass therapy were evaluated (Table 1). There were 37 cases of severe hemophilia and 32 cases of non-severe hemophilia. There were 63 cases of HA, including 50 cases of negative inhibitor and 13 cases of positive inhibitor. After meeting the inclusion and exclusion criteria, 69 patients were evaluated for different types of surgery under clotting factor replacement therapy or bypass therapy during perioperative period. 59 cases underwent major operations, including: 49 cases underwent joint replacement, among which 34 cases underwent single joint replacement and 6 cases underwent double joint replacement and so on. 10 cases underwent minor operations. There were 14 cases of hemophilia with inhibitors, of which 13 were major operations with 175.38 (85.00-270.00) minutes of operation and 2 were minor operations with 45.00 minute of operation. In 12 patients with severe hemophilia and high titer inhibitors, the perioperative consumption of factor FVII was as follows: 447.62 (331.04-738.48)ug/kg on the day of surgery, and the total consumption was 2484.21 (1499.40-4500.00)ug/kg. The perioperative consumption of factor PCC was as follows: 126.10 (0-206.45)ug/kg on the day of surgery, and the total consumption was 1332.84 (529.20-1970.00)ug/kg. The mean preoperative FVIII:C level of the HA patients was 1.19 (0.00~6.00)%, the mean preoperative FIX:C level was 0.022 (0.01~0.07)% of the HB patients.The average intraoperative blood loss of the 69 patients was 537.98 (0-3000) ml. 20 patients received intraoperative transfusion of blood products (red blood cells or fresh frozen plasma) and 49 patients did not receive intraoperative transfusion of blood products. In 55 hemophiliacs without inhibitor, no inhibitor was found after surgery. Conclusion(s) It is safe and effective to adopt different schemes for perioperative alternative therapy for different hemophilia types.

Tuning the Latency by Anionic Ligand Exchange in Ruthenium Benzylidene Phosphite Complexes

Recently discovered cis-dichloro benzylidene phosphite complexes are latent catalysts at room temperature and exhibit exceptional thermal and photochemical activation behavior in olefin metathesis reactions. Most importantly, the study of these catalysts has allowed their introduction in efficient 3-D printing applications of ring-opening metathesis derived polymers and the control of chromatically orthogonal chemical processes. Moreover, their combination with plasmonic Au-nanoparticles has given rise to novel smart materials that are responsive to light. Given the importance of the ligand shell in the initiation and reactivity behavior of this family of complexes, we set out to investigate the effect of anionic ligand exchange. Thus, we report herein two new ruthenium benzylidene benzylphosphite complexes where the chloride anionic ligands have been replaced by bromide and iodide anions (cis-Ru-Phos-Br2 & cis-Ru-Phos-I2). The thermal and photochemical activations of these dormant catalysts in a variety of ring-closing and ring-opening metathesis polymerization (RCM and ROMP) reactions were thoroughly studied and compared with the previously known chloride precatalyst. Photochemical RCM studies provided similar results, especially in non-hindered reactions, with the UV-A wavelength being the best in all cases. On the other hand, the thermal activation profile exposed that the anionic ligand significantly affects reactivity. Notably, cis-Ru-Phos-I2 disclosed particularly impressive initiation efficiency compared to the other members of the family.

An attention mechanism based deep nonlinear ensemble paradigm of strengthened feature extraction method for wind power prediction

The inherent uncertainty of wind power always hampers difficulties in the development of wind energy and the smooth operation of power systems. Therefore, reliable ultra-short-term wind power prediction is crucial for the development of wind energy. In this research, a two-stage nonlinear ensemble paradigm based on double-layer decomposition technology, feature reconstruction, intelligent optimization algorithm, and deep learning is suggested to increase the prediction accuracy of ultra-short-term wind power. First, using two different signal decomposition techniques for processing can further filter out noise in the original signal and fully capture different features within it. Second, the multiple components obtained through double decomposition are reconstructed using sample entropy theory and reassembled into several feature subsequences with similar complexity to simplify the input variables of the prediction model. Finally, based on the idea of a two-stage prediction strategy, the cuckoo search algorithm and the attention mechanism optimized long- and short-term memory model are applied to the prediction of feature subsequences and nonlinear integration, respectively, to obtain the final prediction results. Two sets of data from wind farms in Liaoning Province, China are used for simulation experiments. The final empirical findings indicate that, in comparison to other models, the suggested wind power prediction model has a greater prediction accuracy.

Pediatric Hyperglycemic Hyperosmolar Syndrome: A Comprehensive Approach to Diagnosis, Management, and Complications Utilizing Novel Summarizing Acronyms.

This paper focuses on hyperglycemic hyperosmolar syndrome (HHS), a unique hyperglycemic state requiring divergent diagnosis and treatment approaches from diabetic ketoacidosis (DKA) despite some shared characteristics. We introduce the mnemonic DI-FF-ER-EN-CE-S to encapsulate unique HHS management and complications. 'DI' emphasizes the need to delay and decrease initial insulin therapy until serum glucose decline is managed by fluid resuscitation alone. 'FF' stresses the importance of double fluid replacement compared to DKA due to severe dehydration and 'ER' electrolyte replacement due to profound losses and imbalances. 'EN' denotes the potential for encephalopathy and the requirement for a controlled serum osmolality reduction. 'CE' indicates cerebral edema, a rare complication in HHS. 'S' signifies systemic multiorgan failure. We categorize the associated risks into three mnemonic groups: the 3Rs (renal failure, respiratory distress, rhabdomyolysis), the 3Hs (heart failure, hypercoagulation, hyperthermia), and AP (arrhythmias, pancreatitis) to facilitate awareness and screening of HHS.

Fractional diffusion equation with double and triple Laplace Adomian decomposition methods

Fractional diffusion equation with double and triple Laplace Adomian decomposition methods

Stable Perovskite Quantum Dots Light-Emitting Diodes with Efficiency Exceeding 24.

Perovskite nanocrystals for light-emitting diodes are often synthesized by uncontrollable metathesis reactions, suffering from low product yield, nonuniform growth, and poor stability. Herein, by controlling the nucleation kinetics with high dissociation constant (Ka or Kb) acids or bases, homogenous one-route nucleation of perovskite nanocrystals is achieved as the cluster intermediates are eliminated. The stable, shape uniform, and narrow size distribution green nanocrystals are synthesized. The perovskite nanocrystal film exhibites excellent stability in 80% humidity air with only a 10% photoluminescence intensity drop after 16h. Efficient and stable electroluminescence is demonstrated with an FWHM of 16nm at 517nm. The green devices shows a peak EQE of 24.13% with a lifetime T50 of 54min at 10 000cdm-2 .

Accessing Ta/Cu Architectures via Metal‐Metal Salt Metatheses: Heterobimetallic C−H Bond Activation Affords μ‐Hydrides

AbstractWe employ a metal‐metal salt metathesis strategy to access low‐valent tantalum‐copper heterometallic architectures (Ta−μ2‐H2−Cu and Ta−μ3‐H2−Cu3) that emulate structural elements proposed for surface alloyed nanomaterials. Whereas cluster assembly with carbonylmetalates is well precedented, the use of the corresponding polyarene transition metal anions is underexplored, despite recognition of these highly reactive fragments as storable sources of atomic Mn−. Our application of this strategy provides structurally unique early‐late bimetallic species. These complexes incorporate bridging hydride ligands during their syntheses, the origin of which is elucidated via detailed isotopic labelling studies. Modification of ancillary ligand sterics and electronics alters the mechanism of bimetallic assembly; a trinuclear complex resulting from dinuclear C−H activation is demonstrated as an intermediate en route to formation of the bimetallic. Further validating the promise of this rational, bottom‐up approach, a unique tetranuclear species was synthesized, featuring a Ta centre bearing three Ta−Cu interactions.

Accessing Ta/Cu Architectures via Metal-Metal Salt Metatheses: Heterobimetallic C-H Bond Activation Affords μ-Hydrides.

We employ a metal-metal salt metathesis strategy to access low-valent tantalum-copper heterometallic architectures (Ta-μ2 -H2 -Cu and Ta-μ3 -H2 -Cu3 ) that emulate structural elements proposed for surface alloyed nanomaterials. Whereas cluster assembly with carbonylmetalates is well precedented, the use of the corresponding polyarene transition metal anions is underexplored, despite recognition of these highly reactive fragments as storable sources of atomic Mn- . Our application of this strategy provides structurally unique early-late bimetallic species. These complexes incorporate bridging hydride ligands during their syntheses, the origin of which is elucidated via detailed isotopic labelling studies. Modification of ancillary ligand sterics and electronics alters the mechanism of bimetallic assembly; a trinuclear complex resulting from dinuclear C-H activation is demonstrated as an intermediate en route to formation of the bimetallic. Further validating the promise of this rational, bottom-up approach, a unique tetranuclear species was synthesized, featuring a Ta centre bearing three Ta-Cu interactions.

From an Isolable Bismolyl Anion to an Yttrium-Bismolyl Complex with μ-Bridging Bismuth(I) Centers and Polar Covalent Y-Bi Bonds.

The synthesis and first structural characterization of the [K(18-crown-6)] bismolyl Bitet (C4 Me4 Bi) contact ion pair (1) is presented. Notably, according to Natural Resonance Theory calculations, the Bitet anion of 1 features two types of leading mesomeric structures with localized anionic charge and two lone pairs of electrons at the BiI center, as well as delocalized anionic charge in the π-conjugated C4 Bi ring. The lone pairs at Bi enable a unique bridging coordination mode of the bismolyl ligand, as shown for the first rare earth metal bismolyl complex (Cptet 2 Y)2 (μ-η1 -Bitet )2 (2). The latter results from the salt metathesis reaction of KBitet with Cptet 2 Y(BPh4 ) (Cptet =C5 Me4 H). The Y-Bi bonding interaction in 2 of 16.6 % covalency at yttrium is remarkably large.

Non‐Classical Early Lanthanide(II) Tris(di‐tert‐butylcyclopentadienyl) Complexes**

AbstractWe report the synthesis of a series of temperature‐sensitive non‐classical early Ln(II) (Ln=lanthanide) complexes, [K(2.2.2‐cryptand)][Ln(Cptt)3] (Cptt=C5H3tBu2‐1,3; 1‐Ln; Ln=La−Nd). Complexes 1‐Ln were typically prepared using Schlenk line techniques rather than more common glove box protocols, by the reduction of the parent Ln(III) complexes [Ln(Cptt)3] (2‐Ln) with KC8 in THF in the presence of 2.2.2‐cryptand at −30 °C. The majority of the 2‐Ln series have been reported previously by the salt metathesis reactions of 3 eq. KCptt with parent LnCl3, and these methods were adapted here to afford 2‐Pr. Complexes 1‐Ln and 2‐Pr were characterized by single crystal XRD, elemental analysis, ATR‐IR and UV‐Vis‐NIR spectroscopy; 1‐La and 2‐Pr were additionally characterized by c.w. EPR spectroscopy, and variable temperature magnetic susceptibility measurements were performed on 2‐Pr. During attempts to synthesize 2‐Nd and 2‐Sm we also obtained small crops of crystals of [Nd(Cptt)2(μ‐I)]2 (3) and [Sm(Cptt)2(μ‐Cl)]2 ⋅ C7H8 (4 ⋅ C7H8), respectively; these complexes were also structurally authenticated, and magnetic data was collected for 4 ⋅ C7H8. The combination of data obtained indicate that the Ln(II) centers in 1‐Ln adopt 4fn5d1 electron configurations, in common with other literature examples of [Ln(CpR)3]− anions (CpR=substituted cyclopentadienyl) for these metals.

Iron(II) Complexes of P3 -Chain Ligands: Structural Diversity.

Iron(II) complexes containing ligands with a R2 P-P-PR2 unit were synthesized by metathesis reactions. With R=tBu, a mixture of two isomers is formed; in one of them, the terminal phosphorus binds to the Fe center (ylidic structure), while in the other one, the central P atom is linked to Fe. Starting from differently functionalized parent triphosphanes and corresponding functionalized Fe complexes, the ratio of isomers does not change. The outcome of the reaction and therefore the binding modes of the triphosphane ligands in the resulting compounds can be influenced by the size of the substituents. In the case of R=iPr a chelate complex is formed (both terminal P atoms are linked to the Fe center). Applying the mixed-substituted triphosphane, the ylidic structure of the resulting complex is preferred. The new compounds were characterized by NMR spectroscopy in solution and single-crystal X-ray diffraction in solid-state. The synthetic work was supported by DFT calculations.

Yttrium Complexes with Group 13 Heterobenzene-Type Ligands.

The yttrium gallabenzene complex [(1-Me-3,5-tBu2 -C5 H3 Ga)(μ-Me)Y(2,4-dtbp)] is accessible from Y(GaMe4 )3 and K(2,4-dtbp) via a tandem salt metathesis/methane elimination (2,4-dtbp=2,4-di-tert-butyl-pentadienyl). The pentadienyl ligand in [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(2,4-dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC5 Me5 and KTpMe,Me (TpMe,Me =tris(pyrazolyl-Me2 -3,5)borato) affording [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(TpMe,Me )] and [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(C5 Me5 )]. The yttrium center in [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(2,4-dtbp)] readily forms adducts with neutral Lewis bases like 4-DMAP (4-dimethylaminopyridine), PMe3 , DMPE (1,2-bis(dimethylphosphino)ethane), and DME (1,2-dimethoxyethane). In stark contrast, addition of TMEDA (N,N,N',N'-tetramethylethylenediamine) results in methyl/pentadienyl exchange between aluminum and yttrium resulting in [(1-(2,4-dtbp)-1-Me-3,5-tBu2 -C5 H3 Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single-crystal X-ray diffraction (SCXRD) and heteronuclear (89 Y, 31 P) NMR spectroscopy.

Development of Highly Enantio- and Z-Selective Grubbs Catalysts via Controllable C-H Bond Activation.

Asymmetric olefin metathesis is a powerful strategy for stereocontrolled synthesis that allows the formation of chiral elements in conjunction with carbon-carbon double bonds. Here, we report a new series of cyclometalated stereogenic-at-Ru catalysts that enable highly efficient asymmetric ring opening/cross-metathesis (AROCM) and asymmetric ring-closing metathesis (ARCM) reactions. Single enantiomers of these catalysts with either right-handed or left-handed configurations at the Ru center can be easily accessed via highly stereoselective C-H bond activation-based cyclometalation. Right-handed chiral Ru catalysts enabled the Z- and enantioselective AROCM of a wide range of norbornenes and terminal alkenes, generating densely functionalized cyclopentanes with excellent stereo- and enantioselectivities (99:1 Z/E, up to 99% ee). Left-handed chiral Ru catalysts enabled the facile ARCM of sterically unhindered, all-terminal prochiral trienes, which had not been achieved by previous Ru catalysts, providing simple cyclic ethers and amides with tertiary or quaternary carbon stereocenters with excellent enantioselectivities (up to 99% ee).

Influence of the Morphological and Chemical Properties of Nanosized Metal Oxides on Catalytic Efficiency for the Cycloaddition Reaction of CO<sub>2</sub> to Epoxides

Metal oxides represent “workhorse catalysts” for the chemical industry with multifarious applications in dehydrogenation, metathesis, transesterification, and combustion reactions. It is therefore crucial, for each given catalytic process, to investigate the impact of morphological and physicochemical properties on catalytic performance. Metal oxide materials are being increasingly applied as inexpensive catalytic materials for the cycloaddition of CO2 to epoxides but the correlation between the chemical properties of the metal oxides and their catalytic activity has not been systematically investigated. In this work, we prepared nanostructured tin (IV) oxide (SnO2) and zinc oxide (ZnO) materials with different morphologies such as quantum dots (QDs), nanowires (NWs), microdisks (µDs) and nanoplates (NPLs). Following characterization, these materials were investigated, in combination with low amounts of tetrabutylammonium iodide (TBAI) as a nucleophile, for the CO2 cycloaddition to styrene oxide (SO) yielding cyclic styrene carbonate (SC) under atmospheric pressure. The correlation between catalytic performance, surface area, acidity and basicity was investigated and discussed.

Graph regularized non-negative matrix factorization with L_{2,1} norm regularization terms for drug–target interactions prediction

BackgroundIdentifying drug–target interactions (DTIs) plays a key role in drug development. Traditional wet experiments to identify DTIs are costly and time consuming. Effective computational methods to predict DTIs are useful to speed up the process of drug discovery. A variety of non-negativity matrix factorization based methods are proposed to predict DTIs, but most of them overlooked the sparsity of feature matrices and the convergence of adopted matrix factorization algorithms, therefore their performances can be further improved.ResultsIn order to predict DTIs more accurately, we propose a novel method iPALM-DLMF. iPALM-DLMF models DTIs prediction as a problem of non-negative matrix factorization with graph dual regularization terms and L_{2,1} norm regularization terms. The graph dual regularization terms are used to integrate the information from the drug similarity matrix and the target similarity matrix, and L_{2,1} norm regularization terms are used to ensure the sparsity of the feature matrices obtained by non-negative matrix factorization. To solve the model, iPALM-DLMF adopts non-negative double singular value decomposition to initialize the nonnegative matrix factorization, and an inertial Proximal Alternating Linearized Minimization iterating process, which has been proved to converge to a KKT point, to obtain the final result of the matrix factorization. Extensive experimental results show that iPALM-DLMF has better performance than other state-of-the-art methods. In case studies, in 50 highest-scoring proteins targeted by the drug gabapentin predicted by iPALM-DLMF, 46 have been validated, and in 50 highest-scoring drugs targeting prostaglandin-endoperoxide synthase 2 predicted by iPALM-DLMF, 47 have been validated.

Convergent Total Synthesis of (-)-Cyclopamine.

A concise and enantioselective total synthesis of the Veratrum alkaloid cyclopamine is disclosed. This highly convergent synthesis with a 16-step longest linear sequence (LLS) was enabled by a de novo synthesis of the trans-6,5-heterobicycle via a strain-inducing halocyclization process, a key Tsuji-Trost cyclization to construct the fully substituted, spirocyclic THF motif with exquisite diastereocontrol, and a late-stage ring-closing metathesis (RCM) reaction to forge the central tetrasubstituted olefin.

Preorganized Internal Electric Field Promotes a Double-Displacement Mechanism for the Adenine Excision Reaction by Adenine DNA Glycosylase.

Adenine DNA glycosylase (MutY) is a monofunctional glycosylase, removing adenines (A) misinserted opposite 8-oxo-7,8-dihydroguanine (OG), a common product of oxidative damage to DNA. Through multiscale calculations, we decipher a detailed adenine excision mechanism of MutY that is consistent with all available experimental data, involving an initial protonation step and two nucleophilic displacement steps. During the first displacement step, N-glycosidic bond cleavage is accompanied by the attack of the carboxylate group of residue Asp144 at the anomeric carbon (C1'), forming a covalent glycosyl-enzyme intermediate to stabilize the fleeting oxocarbenium ion. After departure of the excised base, water nucleophiles can be recruited to displace Asp144, completing the catalytic cycle with retention of stereochemistry at the C1' position. The two displacement reactions are found to mostly involve the movement of the oxocarbenium ion, occurring with large charge reorganization and thus sensitive to the internal electric field (IEF) exerted by the polar protein environment. Intriguingly, we find that the negatively charged carboxylate group is a good nucleophile for the oxocarbenium ion, yet an unactivated water molecule is not, and that the electric field catalysis strategy is used by the enzyme to enable its unique double-displacement reaction mechanism. A strong IEF, pointing toward 5' direction of the substrate sugar ring, greatly facilitates the second displacement reaction at the expense of elevating the barrier of the first one, thereby allowing both reactions to occur. These findings not only increase our understanding of the strategies used by DNA glycosylases to repair DNA lesions, but also have important implications for how internal/external electric field can be applied to modulate chemical reactions.