Major Isomer Research Articles

NMR and computational studies on tautomerism of 3-hydroxy-2-(2-thienylcarbonyl)cyclohex-2-en-1-one

The tautomeric system of 3-hydroxy-2-(2-thienylcarbonyl)cyclohex-2-en-1-one 1 has been investigated by NMR spectroscopy between 224 and 298K. At all temperatures an endocyclic enol tautomer was the major isomer; however, at low temperatures two other enol isomers were found. Conformational search of the potential energy surfaces of all tautomers of cyclohexenone 1 was also carried out. Extensive calculations were performed for two triketones and four cis-endocyclic double bond enol tautomers with the lowest energies. Syntheses of 3-methoxy-2-(2-thienylcarbonyl)cyclohex-2-en-1-one 2 and 2-benzoyl-3-hydroxycyclohex-2-en-1-one 3 were carried out to analyze the features of thienyl group rotation and structural differences with a symmetrical substituent, respectively.

Configurational Isomerization of Dinuclear Iridium and Rhodium Complexes with a Series of NPPN Ligands, 2-PyCH2(Ph)P(CH2)nP(Ph)CH2-2-Py (Py = Pyridyl, n = 2–4)

New heterodonor NPPN tetradentate ligands, 2-PyCH2(Ph)P(CH2)nP(Ph)CH2-2-Py (meso- and rac-Ln; n = 2–4, Py = pyridyl), were prepared and reacted with [Cp*MCl2]2 (M = Ir, Rh; Cp* is pentamethylcyclopentadienyl) in the presence of NH4BF4 to afford a series of dinuclear complexes [(Cp*MCl)2(meso-Ln)](BF4)2 (M = Ir, n = 2 (2a), 3 (3a), 4 (4a); M = Rh, n = 2 (2c), 3 (3c), 4 (4c)) and [(Cp*MCl)2(rac-Ln)](BF4)2 (M = Ir, n = 2 (2b), 3 (3b), 4 (4b); M = Rh, n = 2 (2d), 3 (3d), 4 (4d)), which were characterized by IR, 1H and 31P{1H} NMR, and ESI mass spectroscopic techniques and X-ray crystallography. The configurations around the two metal centers were controlled by the configuration of the coordinated P atoms so as to avoid repulsive interaction between the phenyl group on P and the chloride ligand, resulting in the formation of stereospecific isomers; a meso configuration of the metal centers is induced from meso-Ln (abbreviated as meso-P2/meso-M2), and in contrast, a rac configuration is induced from rac-Ln (rac-P2/rac-M2). Furthermore, inversion of metal centers for the Ir2 complexes occurred in DMSO at higher temperatures (60–100 °C), generating equilibrium mixtures of minor diastereomers (meso-P2/rac-M2 or rac-P2/meso-M2) in low ratios together with the major isomers (meso-P2/meso-M2 or rac-P2/rac-M2). The equilibrium constants, K = [minor isomer]/[major isomer], varied appreciably depending on the lengths of the methylene chains as well as configurations of the NPPN ligands; the overall propensity for the K values was observed to be L2 < L3 < L4 and meso-Ln < rac-Ln, while rac-L3, rac-L4, and meso-L4 showed almost identical equilibrium constants, presumably resulting from no steric influence between the two metal centers.

The First Synthesis of Uralenol, 5′-Prenylated Quercetin, via Palladium-Catalyzed­ O-Dimethylallylation Reaction with Concurrent Acetyl Migration

The first synthesis of uralenol, 5′-prenylated quercetin, is described. The key step is a palladium-catalyzed O-1,1-dimethylallylation reaction, with concurrent acetyl migration to afford the desired intermediate as a major isomer, which was purified by recrystallization. Finally, Claisen rearrangement, followed by deprotection of all phenolic protecting groups, afforded uralenol in excellent yield.

Characterization of a Novel α-Conotoxin TxID from Conus textile That Potently Blocks Rat α3β4 Nicotinic Acetylcholine Receptors

The α3β4 nAChRs are implicated in pain sensation in the PNS and addiction to nicotine in the CNS. We identified an α-4/6-conotoxin (CTx) TxID from Conus textile. The new toxin consists of 15 amino acid residues with two disulfide bonds. TxID was synthesized using solid phase methods, and the synthetic peptide was functionally tested on nAChRs heterologously expressed in Xenopus laevis oocytes. TxID blocked rat α3β4 nAChRs with a 12.5 nM IC50, which places it among the most potent α3β4 nAChR antagonists. TxID also blocked the closely related α6/α3β4 with a 94 nM IC50 but showed little activity on other nAChR subtypes. NMR analysis showed that two major structural isomers exist in solution, one of which adopts a regular α-CTx fold but with different surface charge distribution to other 4/6 family members. α-CTx TxID is a novel tool with which to probe the structure and function of α3β4 nAChRs.

One‐Pot Synthesis of (−)‐Oseltamivir and Mechanistic Insights into the Organocatalyzed Michael Reaction

The one-pot sequential synthesis of (-)-oseltamivir has been achieved without evaporation or solvent exchange in 36% yield over seven reactions. The key step was the asymmetric Michael reaction of pentan-3-yloxyacetaldehyde with (Z)-N-2-nitroethenylacetamide, catalyzed by a diphenylprolinol silyl ether. The use of a bulky O-silyl-substituted diphenylprolinol catalyst, chlorobenzene as a solvent, and HCO2 H as an acid additive, were key to produce the first Michael adduct in both excellent yield and excellent diastereo- and enantioselectivity. Investigation into the effect of acid demonstrated that an acid additive accelerates not only the E-Z isomerization of the enamines derived from pentan-3-yloxyacetaldehyde with diphenylprolinol silyl ether, but also ring opening of the cyclobutane intermediate and the addition reaction of the enamine to (Z)-N-2-nitroethenylacetamide. The transition-state model for the Michael reaction of pentan-3-yloxyacetaldehyde with (Z)-N-2-nitroethenylacetamide was proposed by consideration of the absolute configuration of the major and minor isomers of the Michael product with the results of the Michael reaction of pentan-3-yloxyacetaldehyde with phenylmaleimide and naphthoquinone.

Screening Tests for the Rapid Detection of Diarrhetic Shellfish Toxins in Washington State

The illness of three people due to diarrhetic shellfish poisoning (DSP) following their ingestion of recreationally harvested mussels from Sequim Bay State Park in the summer of 2011, resulted in intensified monitoring for diarrhetic shellfish toxins (DSTs) in Washington State. Rapid testing at remote sites was proposed as a means to provide early warning of DST events in order to protect human health and allow growers to test “pre-harvest” shellfish samples, thereby preventing harvest of toxic product that would later be destroyed or recalled. Tissue homogenates from several shellfish species collected from two sites in Sequim Bay, WA in the summer 2012, as well as other sites throughout Puget Sound, were analyzed using three rapid screening methods: a lateral flow antibody-based test strip (Jellett Rapid Test), an enzyme-linked immunosorbent assay (ELISA) and a protein phosphatase 2A inhibition assay (PP2A). The results were compared to the standard regulatory method of liquid chromatography coupled with tandem mass spectroscopy (LC-MS/MS). The Jellett Rapid Test for DSP gave an unacceptable number of false negatives due to incomplete extraction of DSTs using the manufacturer’s recommended method while the ELISA antibody had low cross-reactivity with dinophysistoxin-1, the major toxin isomer in shellfish from the region. The PP2A test showed the greatest promise as a screening tool for Washington State shellfish harvesters.

Crystal and electronic structures of tris[4,4,4-Trifluoro-1-(2-X)-1,3-butanedionato]iron(III) isomers (X = thienyl or furyl): An X-ray and computational study

DFT calculations showed that [Fe(acac)3] (where acac=acetylacetonato) is high-spin, with a negative D3 distortion from the octahedral ligand field. Calculations further showed that, although both the fac and mer isomers of complexes [Fe(CF3COCHCOR)3], where R=C4H3S or C4H3O, can exist, the mer isomers are energetically favoured in both complexes. The structure of the major mer isomer of [Fe(CF3COCHCOC4H3S)3] has been published previously, while the crystal structure of the minor fac isomer of [Fe(CF3COCHCOC4H3S)3] is presented in this study. The structure of the mer isomer of [Fe(CF3COCHCOC4H3O)3], in agreement with DFT calculations, showed that the furyl substituent pointed towards the CF3 group in a syn orientation.

Synthesis of the major isomers of Aprepitant and Fosaprepitant

Abstract The synthesis of two isomers of Aprepitant (APT) and three isomers of Fosaprepitant (FPT), crucial components for quality control in manufacturing, is described. Herein, three chiral centers in the isomers of Aprepitant are established in high yield by induced crystallization and chiral reduction. Additionally, the isomers of Aprepitant are utilized to synthesize the isomers of Fosaprepitant with the same stereochemistry. All the target compounds were confirmed by elemental analyses, IR, NMR and MS data analysis.

Synthesis and Small Molecule Reactivity oftrans-Dihydride Isomers of Ru(NHC)2(PPh3)2H2(NHC = N-Heterocyclic Carbene)

Addition of IMe4 (1,3,4,5-tetramethylimidazol-2-ylidene) to Ru(PPh3)3HCl (in the presence of H2) or Ru(PPh3)4H2 gave the all-trans isomer of Ru(IMe4)2(PPh3)2H2 (1a), whereas 1,3-diethyl-4,5-dimethylimidazol-2-ylidene (IEt2Me2) reacted with Ru(PPh3)4H2 to form cis,cis,trans-Ru(IEt2Me2)2(PPh3)2H2 (2b). H/D exchange of 1a with C6D6 (elevated temperature) or D2 (room temperature) gave Ru(IMe4)2(PPh3)2HD (1a-HD) and Ru(IMe4)2(PPh3)2D2 (1a-D2). CO reacted with 1a to give a mixture of Ru(IMe4)2(PPh3)(CO)H2 (3) and Ru(IMe4)2(CO)3 (4); 2b reacted in a similar manner, although more slowly, allowing isolation of the monocarbonyl species Ru(IEt2Me2)2(PPh3)(CO)H2 (5). Insertion of CO2 into one of the Ru–H bonds of 1a and 2b generated mixtures of major and minor isomers of the κ2-formate complexes Ru(IMe4)2(PPh3)(OCHO)H (7/8) and Ru(IEt2Me2)2(PPh3)(OCHO)H (9/10). The hydridic nature of 1a and 2b was apparent by their reactivity toward MeI, which gave [Ru(IMe4)2(PPh3)2H]I (11), Ru(IEt2Me2)2(PPh3)HI (12), [Ru(IEt2Me2)2(P...

Molecular Structure and Chemical Property of a Divalent Metallofullerene Yb@C2(13)-C84

Endohedral metallofullerenes (EMFs) encapsulating divalent metal ions have received limited attention because of their low production yields. Here, we report the results of structural determination and chemical functionalization of a typical divalent metallofullerene, Yb@C84(II). Single-crystal X-ray crystallographic studies of Yb@C84/Ni(II)(OEP) cocrystals (OEP is the dianion of octaethylporphyrin) unambiguously established the chiral C2(13)-C84 cage structure and revealed multiple sites for Yb(2+), indicating a moving metal ion inside the cage. The chemical property of Yb@C2(13)-C84 was probed with the electrophillic adamantylidene carbene (1). Three monoadduct isomers were isolated and characterized. Crystallographic results of the major isomer (2b) revealed that, although the cycloaddition breaks a [5,6]-bond on the cage, Yb(2+) is localized under a hexagonal ring distant from the sites of addition. Thus, it is proved that the dynamic motion of the divalent metal ion in Yb@C84 has been effectively halted by exohedral functionalization. Spectroscopic results show that the electronic property of Yb@C2(13)-C84 is pertained in the derivatives, although the addend exerts a mild reduction effect on the electrochemical behavior of the EMF. Computational works demonstrated that addition of 1 to Yb@C2(13)-C84 is mainly driven by releasing the local strains of cage carbons rather than charge recombination, which is always prominent to the affinity of typical trivalent EMFs such as M@C2v(9)-C82 (M = Sc, Y, La, Ce, Gd) toward 1. Accordingly, it is speculated that the chemical behaviors of divalent EMFs more likely resemble those of empty fullerenes because both are closed-shell compounds, but they differ from those of trivalent EMFs, which have open-shell electronic configurations instead.

Stereoselective Synthesis of New β-Lactams from 2-(1H-Pyrrol-1-yl)-1-propen-1-one as a Novel Ketene

New trans-β-lactams have been stereoselectively prepared by the reaction of N-pyrrolylpropanoic acid with 2-chloro-1-methylpyridinium iodide and aromatic imines in the presence of triethylamine as a base via in situ generation of methyl-2-(1H-pyrrol-1-yl)ketene as a novel heteroarylketene. The trans-β-lactam was formed either as a single isomer or as the major isomer.

The nitrite-oxidizing community in activated sludge from a municipal wastewater treatment plant determined by fatty acid methyl ester-stable isotope probing

Metabolically-active autotrophic nitrite oxidizers from activated sludge were labeled with 13C-bicarbonate under exposure to different temperatures and nitrite concentrations. The labeled samples were characterized by FAME-SIP (fatty acid methyl ester-stable isotope probing). The compound cis-11-palmitoleic acid, which is the major lipid of the most abundant nitrite oxidizer in activated sludge, Candidatus Nitrospira defluvii, showed 13C-incorporation in all samples exposed to 3mM nitrite. Subsequently, the lipid cis-7-palmitoleic acid was labeled, and it indicated the activity of a nitrite oxidizer that was different from the known Nitrospira taxa in activated sludge. The highest incorporation of cis-7-palmitoleic acid label was found after incubation with a nitrite concentration of 0.3mM at 17 and 22°C. While activity of Nitrobacter populations could not be detected by the FAME-SIP approach, an unknown nitrite oxidizer with the major lipid cis-9 isomer of palmitoleic acid exhibited 13C-incorporation at 28°C with 30mM nitrite. These results indicated flexibility of nitrite-oxidizing guilds in a complex community responding to different conditions. Labeled lipids so far not described for activated sludge-associated nitrifiers indicated the presence of unknown nitrite oxidizers in this habitat. The FAME-SIP-based information can be used to define appropriate conditions for the enrichment of nitrite-oxidizing guilds from complex samples.

Synthesis and antioxidant evaluation of (S,S)- and (R,R)-secoisolariciresinol diglucosides (SDGs)

Secoisolariciresinol diglucosides (SDGs) (S,S)-SDG-1 (major isomer in flaxseed) and (R,R)-SDG-2 (minor isomer in flaxseed) were synthesized from vanillin via secoisolariciresinol (6) and glucosyl donor 7 through a concise route that involved chromatographic separation of diastereomeric diglucoside derivatives (S,S)-8 and (R,R)-9. Synthetic (S,S)-SDG-1 and (R,R)-SDG-2 exhibited potent antioxidant properties (EC50=292.17±27.71μM and 331.94±21.21μM, respectively), which compared well with that of natural (S,S)-SDG-1 (EC50=275.24±13.15μM). These values are significantly lower than those of ascorbic acid (EC50=1129.32±88.79μM) and α-tocopherol (EC50=944.62±148.00μM). Compounds (S,S)-SDG-1 and (R,R)-SDG-2 also demonstrated powerful scavenging activities against hydroxyl [natural (S,S)-SDG-1: 3.68±0.27; synthetic (S,S)-SDG-1: 2.09±0.16; synthetic (R,R)-SDG-2: 1.96±0.27], peroxyl [natural (S,S)-SDG-1: 2.55±0.11; synthetic (S,S)-SDG-1: 2.20±0.10; synthetic (R,R)-SDG-2: 3.03±0.04] and DPPH [natural (S,S)-SDG-1: EC50=83.94±2.80μM; synthetic (S,S)-SDG-1: EC50=157.54±21.30 μM; synthetic (R,R)-SDG-2: EC50=123.63±8.67 μM] radicals. These results confirm previous studies with naturally occurring (S,S)-SDG-1 and establish both (S,S)-SDG-1 and (R,R)-SDG-2 as potent antioxidants and free radical scavengers for potential in vivo use.

The trans fatty acid content in human milk and its association with maternal diet among lactating mothers in Malaysia.

Excessive intake of trans fatty acids (TFA) could reduce the fat density of human milk and impair the desaturation of essential fatty acids. Because the mammary glands are unable to synthesize TFA, it is likely that the TFA in human milk come from dietary intake. Thus, the aim of this study was to investigate the sources of TFA intake for lactating mothers in one of the urban areas in Selangor. In this cross-sectional study, anthropometric measurements, FFQ including 7 food groups and dietary consumption data were collected from 101 lactating mothers. Five major TFA isomers (palmitoelaidic acid (16:1t9), petroselaidic acid (18:1t6), elaidic acid (18:1t9), vaccenic acid (18:1t11) and linoelaidic acid (18:2t9,12) in human milk were measured by gas chromatography (GC). The relationship between food consumption and TFA levels was assessed using the non-parametric Spearman's rho test. The TFA content in human milk was 2.94±0.96 (SEM) % fatty acid; this is considered low, as it is lower than 4%. The most abundant TFA isomer was linoelaidic acid (1.44±0.60% fatty acid). A sub-experiment (analyzing 3 days of composite food consumption) was conducted with 18 lactating mothers, and the results showed that linoelaidic acid was the most common TFA consumed (0.07±0.01 g/100 g food). Only 10 food items had an effect on the total TFA level and the isomers found in human milk. No association was found between TFA consumption and the TFA level in human milk.

Barrierless Inter and Intramolecular Proton Transfer; A DFT Study of Tautomerism in Microsolvated and Protonated Systems

DFT calculations were employed to study tautomers of 2,2-di(pyrimidin-2-yl)acetic acid (DPA) in the gas phase and in the presence of water, methanol, DMSO (microsolvation models), and proton (H(+)). In the gas phase, all three tautomers were in equilibrium with each other (T2 was slightly more favorable); but, in microsolvation with protic solvent, T3 was a major isomer. Moreover, unexpectedly enough, T1 (common form of DPA) was the least stable tautomer in the gas phase, while, in the water (as solvent), T1 was the most stable one. The calculated energy values indicated a very special barrierless tautomeric system between T2 and T3. In the gas phase, ΔG(#) for T2 → T3 was only 0.30 kcal/mol, while it was 56.4 and 44.8 kcal/mol for T2 → T1 and T3 → T1, respectively. Rate constants for conversion of T2 into T3 were high in all cases, and their values in the gas phase and in the presence of water, methanol, DMSO, and proton were 3.6 × 10(12), 3.3 × 10(9), 2.7 × 10(11), 2.3 × 10(12), and 2.3 × 10(12) s(-1), respectively. All types of microsolvation slightly decreased the rate constant of this conversion. The rate constant for conversion of T2 into T1 (1,3-H shift) in the gas phase and in the presence of water, methanol, DMSO, and proton was 3.0 × 10(-29), 2.2 × 10(5), 1.1 × 10(-34), 5.2 × 10(-40), and 4.2 × 10(-26) s(-1), respectively. These values showed that only microsolvation with water strongly increased rate constants of tautomerism for T2 → T1 and this type of tautomerism was impossible in the gas phase or other microsolvation models. Although using water as the solvent enhanced rate constants of all types of tautomeric interconversions, its enhancement was less than that of microsolvation with water.

Characterization of mycobacterial triacylglycerols and monomeromycolyl diacylglycerols from Mycobacterium smegmatis biofilm by electrospray ionization multiple-stage and high-resolution mass spectrometry

The storage of triacylglycerols (TAGs) is essential for non-replicating persistence relevant to survival and the re-growth of mycobacteria during their exit from non-replicating state stress conditions. However, the detailed structures of this lipid family in mycobacteria largely remain unexplored. In this contribution, we describe a multiple-stage linear ion-trap mass spectrometric approach with high resolution mass spectrometry toward direct structural analysis of the TAGs, including a novel lipid subclass previously defined as monomeromycolyl diacylglycerol (MMDAG) isolated from biofilm of Mycobacterium smegmatis, a rapidly growing, non-pathogenic mycobacterium that has been used as a tool for molecular analysis of mycobacteria. Our results demonstrate that the major isomer in each of the molecular species of TAGs and MMDAGs consists of the common structure in which Δ(9)18:1- and 16:0-fatty acyl substituents are exclusively located at sn-1 and sn-2, respectively. Several isomers were found for most of the molecular species, and thus hundreds of structures are present in this lipid family. More importantly, this study revealed the structures of MMDAG, a novel subclass of TAG that has not been previously reported by direct mass spectrometric approaches.

Computational and Experimental Investigations into the Conformations of Cyclic Tetra-α/β-peptides

We present a combined computational and experimental study of the energy landscapes of cyclic tetra-α/β-peptides. We have performed discrete path sampling calculations on a series of cyclic tetra-α/β-peptides to obtain the relative free energies and barriers to interconversion of their conformers. The most stable conformers of cyclo-[(β-Ala-Gly)2] contain all-trans peptide groups. The relative energies of the cis isomers and the cis-trans barriers are lower than in acyclic peptides but not as low as in the highly strained cyclic α-peptides. For cyclic tetra-α/β-peptides containing a single proline residue, of the type cyclo-[β-Ala-Xaa-β-Ala-Pro], the energy landscapes show that the most stable isomers containing cis and trans β-Ala-Pro have similar free energies and are separated by barriers of approximately 15 kcal mol(-1). We show that the underlying energy landscapes of cyclo-[β-Ala-Lys-β-Ala-Pro] and cyclo-[β-Ala-Ala-β-Ala-Pro] are similar, allowing the substitution of the flexible side chain of Lys with Ala to reduce the computational demand of our calculations. However, the steric bulk of the Val side chain in cyclo-[β-Ala-Val-β-Ala-Pro] affects the conformations of the ring, leading to significant differences between its energy landscape and that of cyclo-[β-Ala-Ala-β-Ala-Pro]. We have synthesized the cyclic peptide cyclo-[β-Ala-Lys-β-Ala-Pro], and NMR spectroscopy shows the presence of conformers that interconvert slowly on the NMR time scale at temperatures up to 80 °C. Calculated circular dichroism (CD) spectra for the proposed major isomer of cyclo-[β-Ala-Ala-β-Ala-Pro] are in good agreement with the experimental spectra of cyclo-[β-Ala-Lys-β-Ala-Pro], suggesting that the Ala cyclic tetrapeptide is a viable model for the Lys analogue.

A highly selective whole cell biocatalysis method for the production of two major bioactive conjugated linoleic acid isomers

Abstract Conjugated linoleic acid (CLA) is well known potential anticarcinogenic, antiatherogenic and a number of other therapeutic qualities bearing substance. In the present study we have isolated Lactobacillus plantarum from local dairy buffalo milk and used as a whole cell biocatalyst, for selective CLA isomer production from linoleic acid (LA). Quantitative analysis revealed that the cis-9, trans-11 CLA comprised of 51% (w/w), while trans-10, cis-12 CLA accounted for 49% (w/w) of total CLA produced by L. plantarum. The product formation and quantitation was monitored by the spectrophotometric method and the individual isomers separation was done with GC–FID. After optimization of biotransformation conditions such as pH, LA concentration, effect of preincubation, fermentation time; the highest CLA production (19.07% conversion) was achieved at 120 h in the presence of 1.62 mg ml−1 of LA. The results revealed that the bacterium is an efficient biocatalyst for the production of two major bioactive CLA isomers using LA as a substrate.

Levels and profiles of Dechlorane Plus in a major E-waste dismantling area in China

Dechlorane Plus (DP) is a high-production volume, chlorinated flame retardant comprising two major isomers, syn- and anti-DP. In this study, levels of DP were measured in soil and earthworm samples in farmland from a typical E-waste dismantling area in China. The concentrations of total DP ranged from 0.17 to 1,990ngg(-1)dw in soil samples and 3.43 to 89.2ngg(-1)lw in earthworm samples. Higher DP levels were found in some main E-waste dismantling sites than those in other sites. The ratios of anti-DP to total DP (f anti) ranged from 0.57 to 0.80 in soil samples and 0.47 to 0.81 in earthworm samples, respectively. The f anti in most samples in this study was in the range of the reported technical DP values. These results showed that improper E-waste dismantling activities could result in the emission of DP. Most earthworm samples showed very low BSAFs (biota-to-soil accumulation factors) for total DP. The values of BSAF were in the range of 0.0007-1.85, with an average value of 0.23. This study presents the first report of the DP in earthworms, which would be useful for ecological risk assessment of DP in terrestrial ecosystem.

C20H4(C4F8)3: A Fluorine‐Containing Annulated Corannulene that Is a Better Electron Acceptor Than C60

At sixes and sevens: The reaction of corannulene with 35 equivalents of 1,4-C4F8I2 is an efficient and a relatively selective process that yields two main products in which six H atoms are substituted with three C4F8 moieties that form six- and seven-membered rings. Low-temperature photoelectron spectroscopy showed the electron affinity of the major isomer (shown) exceeds that of C60 (2.74±0.02 and 2.689±0.008 eV, respectively).