bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of Dipeptidyl Carboxypeptidase Activity of Thermolysin
Authors: Fukuda Mitsuhiro , Kunugi Shigeru 
Published: July 2006

Abstract
Steady state and presteady state kinetic analyses were performed for thermolysin-catalyzed hydrolysis of chromophoric tripeptide substrates with free carboxyl terminal. The pH dependence of kcat showed fairly higher pKa (\simeq7) than that of the second-order rate parameter(kcat⁄Km)(\simeq5) and the pH-dependence of Km resembled that of Ki for N-blocked dipeptidyl inhibitor observed before (S. Kunugi et al., Eur. J. Biochem. 124, 157 (1982)). These findings indicated that the reaction with this type of substrate involves a nonproductive binding mode. In a presteady state kinetic study by stopped-flow method, a burst process of 10–20 ms order was observed before the linear steady state at a relatively low pH and temperature. This process showed moderate pH dependence. Considering these experimental results coupled with those accumulated so far on this enzyme, a unified mechanism including a nonproductive binding and an isomerization process in prior to the cleavage of the peptide bond was proposed for the dipeptidyl carboxypeptidase activity of this enzyme.
Formation of Aluminosilicate by Adsorption of Silicic Acid on Aluminium Hydroxide
Authors: Yokoyama Takushi , Nakamura Osamu , Tarutani Toshikazu 
Published: July 2006

Abstract
When monosilicic acid was adsorbed on aluminium hydroxide, allophane-like compound rapidly formed and the monosilicic acid adsorbed was consumed by the formation of the allophane-like compound until the Si/Al mole ratio of the sample reached 0.33–0.39. Above these ratio, the formation of polysilicic acid occured.
Studies of Bitter Peptides from Casein Hydrolyzate. V. Bitterness of the Synthetic N-Terminal Analogs of des-Gly2–BPIa (Arg–Pro–Pro–Phe–Ile–Val)
Authors: Kanehisa Hidenori , Okai Hideo 
Published: July 2006

Abstract
In order to investigate how the basic amino acid residue in the N-terminal contributes to the bitter taste exhibited by BPIa (Arg–Gly–Pro–Pro–Phe–Ile–Val), we synthesized several kinds of N-terminal analogs of des-Gly2–BPIa (Arg–Pro–Pro–Phe–Ile–Val). The basic amino acid residue of BPIa was found to play an important role in its bitter taste.
The Alkylation of 1-Hydroxyanthraquinone with Visible-light Irradiation
Authors: Tajima Masahiro , Inoue Haruo , Hida Mitsuhiko 
Published: July 2006

Abstract
The 2-position of 1-hydroxyanthraquinone was alkylated by the use of tertiary amine or methanol with visible-light irradiation (λ&gt;400 nm).
Kinetic Study of Excited Diatomic Molecules of Krypton and Xenon
Authors: Ito Yoshiro , Arai Shigeyoshi 
Published: July 2006

Abstract
Excited diatomic molecules of krypton and xenon in 13Σu+ states, Kr2* and Xe2*, were produced by irradiating krypton and xenon in the presence of an excess of argon with short electron-beam pulses. The kinetic behaviors of Kr2* and Xe2* (monitored by near-IR absorption spectrophotometry) are explained quantitatively in terms of mechanisms involving three-body association and radiative decay. The rate constants were found to be (6.5±0.8)×10−33 cm6s−1 for Kr*+Kr+Ar→Kr2*+Ar and (1.6±0.3)×10−32 cm6 s−1 for Xe*+Xe+Ar→Xe2*+Ar. The rate constants for the quenching reactions of Kr2* were determined for Xe, H2, O2, N2, CO, and NO.
Photocatalytic Reactions of Azide Ions on Platinized Titanium Dioxide Powders in Solutions
Authors: Nosaka Yoshio , Ishizuka Yutaka , Norimatsu Kohji , Miyama Hajime 
Published: July 2006

Abstract
Ammonia was formed photocatalytically from an aqueous solution of azide ion by using illuminated Pt/TiO2 semiconductor powder. The reaction products, NH3, N2, and small amounts of N2O and NO3−, were detected. Hydrogen, O2 and N2H4 were not formed in the primary reaction products. From these results, together with photoelectrochemical measurements, a mechanism of the ammonia formation from azide ion and water is presented.
The Crystal Structure of 3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide and Hydrogen Bonding Scheme of Anticonvulsant Drugs with Adenine
Authors: Takimoto Midori , Takenaka Akio , Sasada Yoshio 
Published: July 2006

Abstract
3-(Adenin-9-yl)-N-(2-succinimidyl)propionamide has been synthesized as a model for studying the interaction between cyclic ureide and adenine, and its crystal structure examined. The crystals are monoclinic, the space group P21/c, with unit-cell dimensions of a=10.861(1), b=12.766(1), c=9.753(1) Å, β=91.10(1)°, and Z=4. The ureide moiety is hydrogen bonded to adenine with NH···N(1) (2.903(3) Å) and O···HN(6) (2.955(3) Å). A comparison of the hydrogen bonding patterns of the related compounds with adenine suggests that cyclic ureide anticonvulsant drugs possess the capability of interacting with N(1) and N(6) sites of adenine.
Preparation of {N-(2-Aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) Complex, and Separation and Optical Resolution of the Isomers
Authors: Ishii Minoru 
Published: July 2006

Abstract
The mixed ligand complex {N-(2-aminoethyl)-1,3-propanediamine}(diethylenetriamine)cobalt(III) was prepared. Of the five possible geometrical isomers, two were isolated by column chromatography; their formation ratio was ca. 6:4. Both isomers were completely resolved by chromatography. Their configurations were assigned to the meridional type on the basis of electronic, infrared, and circular dichroism spectroscopy, and the X-ray analysis data.
Formation of an N,N-Bidentate Chelate, Bis[4-(4-methyl-2-pyridylazo)resorcinol]nickel(II) Perchlorate, in Dioxane
Authors: Kudo Yoshihiro , Yoshida Noboru , Imamura Taira , Fujimoto Masatoshi 
Published: July 2006

Abstract
The formation of a new N,N-bidentate complex of nickel(II) perchlorate with an N,N,O-terdentate ligand, 4-(4-methyl-2-pyridylazo)resorcinol (4-MePAR), was first detected in dioxane spectrophotometrically. The stability of the N,N-bidentate species in dioxane is strongly affected by the presence of a proton acceptor such as water, ethanol, imidazole, and Cl−, which promote the coordination of the ortho phenolic oxygen in the ligand to form the N,N,O-terdentate complex. The new complex was isolated from dioxane solution and identified to be an N,N-bidentate complex salt, [Ni(4-mepar)2](ClO4)2, having two counter ions, ClO4−. A distortedplanar configuration of the complex was suggested on the basis of IR, X-ray photoelectron spectroscopic, and magnetic measurements.
Viscosity of the Quaternary Gaseous Mixture He–N2–O2–CO2
Authors: Boushehri Ali , Rahmansetayesh Shahrbanoo 
Published: July 2006

Abstract
The kinetic theory expressions for multicomponent gas mixtures are used in conjunction with the law of corresponding states formulated by Kestin, Ro and Wakeham to generate the viscosities of the quaternary gaseous mixture He–N2–O2–CO2. The calculated viscosities are compared with direct measurements performed in a capillary flow apparatus.
Chemical Effects on the X-ray K Emission Spectra of Phosphorus in Organic Compounds
Authors: Yasuda Seiji 
Published: July 2006

Abstract
Spectral changes in the P Kα and P Kβ X-ray emission lines of solid organic phosphorus compounds were measured with a two-crystal X-ray spectrometer. The P Kα line shifted to higher energies with an increasing number of oxygen atoms attached directly to a phosphorus atom. Similar shifts were found in the P Kα satellites, which were always 1.5–2.0 times larger than those of the parent Kα line. There was no simple correlation for relating the P Kβ1 shift to the phosphorus form. The P Kβ profiles of organic phosphorus seemed to be characterized by the surrounding atoms or groups. The appearance of the Kβ′ band offered possible evidence for the existence of phosphorus-oxygen bonding in the samples.
Preparation, and Thermal and Electronic Properties of Double Complex Salts and Cyanide-bridged Complexes Containing Cationic Copper(II) Complexes and Hexacyanoferrate(II) Ion
Authors: Suzuki Masatatsu , Uehara Akira 
Published: July 2006

Abstract
Reaction of copper(II) ion with hexacyanoferrate(II) ion, [Fe(CN)6]4−, in an aqueous solution containing such an amine as en (1,2-ethanediamine), tn (1,3-propanediamine), dien (bis(2-aminoethyl)amine), or dpt (bis(3-aminopropyl)amine), gave two types of complexes: Double complex salts, [Cu(en or tn)2]2[Fe(CN)6]·nH2O(n=5–8), and cyanide-bridged complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O. The infrared spectra of the complexes in the νCN region revealed that the complexes, [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, contain cyanide bridges, while in [Cu(en or tn)2]2[Fe(CN)6]·nH2O, no cyanide bridge is present. The thermal reactions of the complexes in the solid state were investigated by means of derivatography under dynamic conditions (D conditions). It was found that dehydration from [Cu(en)2Fe(CN)6]·nH2O resulted in formation of cyanide bridge in the apical position of square planer [Cu(en)2]2+. For [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O, dehydration resulted in the formation of additional cyanide bridges. All the complexes showed metal to metal (iron(II) to copper(II)) charge-transfer transitions (MMCT) in the near ultraviolet or visible region. The complexes, [Cu(en or tn)2]2[Fe(CN)6]·nH2O, exhibited the outer sphere iron(II) to copper(II) charge-transfer bands (OSMMCT) in the near ultra-violet region. [(Cu(dien or dpt))2(NC)2Fe(CN)4]·4H2O and the dehydrated complexes prepared by thermal reaction showed the inner-sphere iron(II) to copper(II) charge transfer bands (ISMMCT) in the visible region. A good correlation was observed between the energies of the MMCT and the d-d band maxima of copper(II) ions.
Desulfurization of N,N′-Diarylthioureas by Lead Tetraacetate Oxidation
Authors: Debroy Abhijit , Nandy Mazumdar Sujit , Barua Parag D , Mahajan Mahinder P 
Published: July 2006

Abstract
Lead tetraacetate oxidation of N,N′-diarylthioureas in refluxing dichloromethane and pyridine gave the corresponding N,N′-diarylureas. Sulfur was isolated during each oxidation reaction.
Electrochemical Reduction of Cyclic and Acyclic Sulfates
Authors: Nonaka Tsutomu , Kihara Shuta , Fuchigami Toshio , Baizer Manuel M 
Published: July 2006

Abstract
It was confirmed that cyclic and acyclic sulfates of diols and monoalcohols could be reduced at cathodes in nonaqueous solvents. The reduction products were greatly affected by the molecular structures of the sulfates. The reduction of the cyclic sulfates of 1,2-diols yielded the corresponding alkenes and disulfate dianions of the parent diols in high yields and current efficiencies were based on one-electron reduction. On the other hand, the cyclic sulfates of 1,3- and 1,4-diols were also reduced by one-electron transfer under similar conditions, but the cycloalkanes expected were not formed and the products were cyclic ethers along with acyclic alkane or unsaturated alcohol. The reduction of the cyclic sulfate of hydrated formaldehyde, which is regarded as a 1,1-diol, did not give any identified products except for a small amount of methane. Finally, acyclic dialkyl sulfates were reduced by one-electron transfer to give complicated mixtures consisting of monomeric alkanes and alkenes, dimeric alkanes, ethers, and/or alkyl metals. Based on the results obtained, the mechanism of reduction of sulfates (mainly cyclic sulfates of 1,2-diols) is discussed.
Studies on the Mechanism of Zeolite X Crystallization. II. Effect of Silica Sources of Starting Materials on the Gas-phase Adsorption at Solid Phases
Authors: Hino Ryozi , Aoi Hiroyasu , Toki Kenzi 
Published: July 2006

Abstract
The mechanism of zeolite X crystallization was studied by using two kinds of silica sources, tetraethyl orthosilicate and silica sol. The adsorption of benzene and cyclohexane was subjected to a measurement to clarify the distribution of cation Na+ and the change in the pore structure and surface of solid phases with reaction progress. The relation between specific surface area and reaction time has been revealed by means of adsorption of nitrogen gas, benzene, and cyclohexane as follows: 1) In the early stage of reaction or in the amorphous solid state, N2≈C6H6≈C6H12 for tetraethyl orthosilicate and N2≈C6H6&gt;C6H12 for silica sol; 2) for crystals in the early stage, N2&gt;C6H12&gt;C6H6 for tetraethyl orthosilicate and N2&gt;C6H12≈C6H6 for silica sol; 3) for crystals in a sufficiently developed stage, N2&gt;&gt;C6H12&gt;C6H6 for tetraethyl orthosilicate and N2≈C6H6&gt;C6H12 for silica sol. In the case of silica sol, the crystallization mechanism is based on inhomogeneous nucleation; a number of critical nuclei may be generated but their dimension is small. In the case of tetraethyl orthosilicate critical nuclei are fewer in number and larger in size than in the case of silica sol; the mechanism of crystallization is based on homogeneous nucleation.
Liquid Crystal Materials with Sulfur Atoms Incorporated in the Principal Structure 2. New Liquid Crystal Compounds; 2-Substituted-5-(p-substituted phenyl)-1,3-dithianes
Authors: Haramoto Yuichiro , Akazawa Koji , Kamogawa Hiroyoshi 
Published: July 2006

Abstract
2-Substituted-5-(p-substituted phenyl)-1,3-dithianes (8), new liquid crystals, were synthesized. The mesomorphic properties of these compounds were compared with those of the corresponding 2-(p-substituted phenyl)-5-alkyl-1,3-dithianes (9). The main difference found between these two liquid-crystal compounds was that some of 8 exhibited both monotropic nematic and smectic liquid-crystal phases but 9 exhibited only the monotropic nematic phase. This difference seems to originate in somewhat increased lateral interactions between molecules. Even for the three-ring compounds, many of them exhibited the monotropic liquid-crystal behavior. This should mean that these 1,3-dithiane compounds strongly tend to exhibit the monotropic liquid-crystal behavior.
Cross Diene-transmissive Diels-Alder Cycloaddition Reaction of Bis(silyloxy) Cross-conjugated Trienes
Authors: Tsuge Otohiko , Kanemasa Shuji , Sakoh Hirohiko , Wada Eiji 
Published: July 2006

Abstract
Cross type of diene-transmissive Diels-Alder cycloaddition has been demonstrated by using two bis-silyloxy cross-conjugated trienes. The first cycloaddition stage of cross reaction, which has to be highly selective in the formation of mono-cycloadducts, has been performed by the reactions of an activated triene with cyclic olefins or those of trienes with acyclic olefins.The secod cycloadditions with a variety of dienophiles provide cross types of bis-adducts. The characteristics of these cross reactios are discussed.
Reformatsky Type Reaction with New Aluminium Reagents Containing Al–Sn or Al–Pb Linkage
Authors: Matsubara Seijiro , Tsuboniwa Noriyuki , Morizawa Yoshitomi , Oshima Koichiro , Nozaki Hitosi 
Published: July 2006

Abstract
Treatment of α-bromo carbonyl compounds with the reagent prepared from n-Bu3SnLi and Et2AlCl or from SnCl2 and Et2AlCl affords enolates which react with ketone or aldehyde to give β-hydroxy carbonyl compounds in good to excellent yields. The reactions proceed similarly with the reagents which are generated from R3PbLi (R=Ph, n-Bu) and Et2AlCl. Catalysis by the added Pd(PPh3)4 complex promotes the reduction effectively and improves the yields of the desired adducts. The regio- and stereoselectivities are disclosed.
The Molecular Structure of Trimethylamine-Borane as Studied from Gas Electron Diffraction and Spectroscopic Data
Authors: Iijima Kinya , Adachi Nobuhiro , Shibata Shuzo 
Published: July 2006

Abstract
The molecular structure of trimethylamine–borane (CH3)3N·BH3 has been determined from gas electron-diffraction data with spectroscopic data. The molecular parameter values and their uncertainties are rg(B–H)=1.261±0.006 Å, rg(N–B)=1.656±0.002 Å, rg(C–N)=1.485±0.001 Å, rg(C–H)=1.108±0.002 Å, ∠HBH=112.8±0.4°, and ∠CNC=109.2±0.2°. The potential barrier around the N–B bond has been estimated to be larger than 5 kcal mol−1 (1 cal=4.183 J). The isotope effects on the B–D bond distance and the DBD angle have also been estimated to be −0.006 Å and 0.4°, respectively, in rα0 parameters.
Synthesis and Characterization of Iron(III) Complexes with Unsymmetrical Quadridentate Schiff Bases, and Spin Equilibrium Behavior in Solution
Authors: Matsumoto Naohide , Kimoto Kazuhiro , Ohyoshi Akira , Maeda Yonezo 
Published: July 2006

Abstract
Several iron(III) complexes with planar unsymmetrical quadridentate Schiff bases composed of 1:1:1 condensation products of acetylacetone, ethylenediamine, and each of salicylaldehyde and o-hydroxyacetophenone have been prepared and characterized, where the Schiff bases are abbreviated as [H2salacen] and [H2hapacen], respectively. The effective magnetic moment of [FeCl(hapacen)] increases gradually from 3.46 BM at 80 K to 5.31 BM at 301 K, and was interpreted by a spin-spin interaction model based on a binuclear structure with an antiferromagnetic interaction parameter of J=−10 cm−1 (S1=S2=5⁄2), while the magnetic moment for [FeCl(salacen)] is 5.86 BM at 80 K and 5.96 BM at 302 K, indicating that the complex is a monomeric species of high-spin type. The bis(imidazole)iron(III) complexes [Fe(im)2(salacen)]BPh4·CH3OH and [Fe(im)2(hapacen)]BPh4·2CH3OH showed a striking thermochromic behavior in various organic solvents, changing from dark red to green with decrease of the temperature. The complexes are essentially of low-spin type in solids, where im and BPh4 denote imidazole and tetraphenylborate, respectively. Electronic, 1H NMR (Evans method), and ESR spectra confirmed that the thermochromism is caused by spin-equilibrium between high-spin(S=5⁄2) and low-spin(S=1⁄2) states of iron(III).
Studies of Polystyrene-based Ion Exchange Fiber. II. A Novel Fiber-form Catalyst for Sucrose Inversion and Methyl Acetate Hydrolysis
Authors: Yoshioka Toshio , Shimamura Masaharu 
Published: July 2006

Abstract
To obtain a novel acid-base catalyst of high activity and easy treatment, we have prepared polystyrene-based fibrous ion exchange catalysts which have large surface areas per unit of weight and which can be utilized in various forms. They are excellent in chemical stability and mechanical strength due to their composite structures, reinforced with polypropyrene. The reactions of sucrose inversion and methyl acetate hydrolysis were carried out by using these cation exchange fibers and ordinary cation exchange resins. The fiber has about sixteen times as high a catalytic activity per equivalent acid as the resin in the case of sucrose inversion. The intrinsic rate constant in the fiber phase is evaluated to be 2.4 times larger than that in the resin phase in terms of the solid-catalysis theory considering the catalytic effectiveness factor and the absorption coefficient. On the other hand, the catalytic activity per equivalent acid of the fiber is almost equal to that of the resin in the case of methyl acetate hydrolysis. It is suggested that this different behavior is attributable to the different molecular sizes of the reactants.
Reaction of Allene with Water Catalyzed by Palladium(0) in the Presence of Carbon Dioxide
Authors: Inoue Yoshio , Ohtsuka Yukihiro , Hashimoto Harukichi 
Published: July 2006

Abstract
A novel reaction involving allene and water took place using palladium(0)–triphenylphosphine as a catalyst in the presence of carbon dioxide to yield 3-methyl-2-methylene-3-buten-1-ol, selectively. A related reaction of allene with methanol or ethanol was found to occur without carbon dioxide.
Alkoxylation of Ferrocene by Photolysis of Haloferrocenes in Aqueous Alcohols
Authors: Shibata Katsuyoshi , Saito Yoshiyuki , Matsui Masaki , Takase Yoshimi 
Published: July 2006

Abstract
The UV irradiation of haloferrocenes in aqueous alcohols resulted in an alcoholysis with the formation of the corresponding alkoxyferrocenes accompanied by the formation of ferrocence. The order of the reactivities of haloferrocenes was I&gt;Br&gt;Cl.
Determination of the Vapor Pressures of Lithium Iodide and Potassium Chloride by Molecular Beam Surface Ionization
Authors: Kawano Hiroyuki , Kenp\={o} Tsutomu 
Published: July 2006

Abstract
Combined techniques of molecular beam effusion from a Knudsen cell and of positive surface ionization on a heated polycrystalline rhenium filament were employed to determine the vapor pressures P (in atm) of LiI and KCl as a function of cell temperature T (in K), thereby yielding the equations:
log10P(LiI)=(7.498±0.046)−(9254±30)⁄T for 583–717 K,
log10P(KCl)=(7.210±0.058)−(11135±45)⁄T for 687–877 K.
The present data on the pressure and on both entropy and enthalpy of sublimation are compared with others in literature.
Magnetic Circular Dichroism Studies of Bipyridyls
Authors: Uchimura Hiroyuki , Tajiri Akio , Hatano Masahiro 
Published: July 2006

Abstract
The magnetic circular dichroism (MCD) and UV absorption spectra of 2,2′- and 4,4′-bipyridyl in cyclohexane and sulfuric acid were measured at room temperature. The MCD spectrum of 2,2′-bipyridyl is different from that of 4,4′-bipyridyl, reflecting the difference in molecular symmetry between them. The absorption and MCD spectral profiles of 2,2′-bipyridyl in cyclohexane are different from those of 2,2′-bipyridyl in mineral acids, in this system protonation taking place on the nitrogen atoms to give a mono- or di-cation with low symmetry. On the contrary, the MCD spectra of 4,4′-bipyridyl in cyclohexane and in acidic media at pH 0.98 exhibit a similar spectral profile to each other due to the D2 symmetry being retained in 4,4′-bipyridyl. Theoretical calculations were carried out on the basis of the PPP-SCF-CI method to get a reasonable explanation for the observed MCD spectra. The assignments of the MCD bands of these compounds are given and their dihedral angles are estimated.
Studies of the Metal Complexes of Cyclohexane Derivatives. VIII. Preparation and Properties of Platinum(II) and Cobalt(III) Complexes Containing (1R,2S,3S)- or (1S,2R,3R)-3-Methyl-1,2-cyclohexanediamine
Authors: Saito Reiko , Kidani Yoshinori 
Published: July 2006

Abstract
(1RS,2SR,3SR)-3-Methyl-1,2-cyclohexanediamine (3m-chxn), a methyl derivative of cis-1,2-cyclohexanediamine, was prepared and optically resolved. The absolute configurations of the enantiomers obtained were assigned on the basis of the Cotton effect of the trans-dichlorobis(diamine) complexes, each containing active 3m-chxn. The complexes of the [Pt(NH3)2L]2+, [Pt(en)L]2+, and [CoL3]3+ types (en=1,2-ethanediamine, L=R,S,S- or S,R,R-3m-chxn) were also synthesized and characterized on the basis of their absorption, CD, and 13C NMR spectra. It has been found that the chelate rings adopted by R,S,S- and S,R,R-3m-chxn predominantly take the δ and λ conformations respectively, because of the preferred equatorial orientation of the C2–C3 bond of the cyclohexane ring. The four diastereomers of [Co(R,S,S-3m-chxn)3]3+ were chromatographically isolated and assigned to fac-Λ(lel3), mer-Λ(lel3), fac-Δ(ob3), and mer-Δ(ob3).
Effects and Role of the Substituents upon 2-Pyridone-catalyzed Mutarotation of 2,3,4,6-Tetra-O-methyl-d-glucose
Authors: Kuzuya Masayuki , Noguchi Akihiro , Okuda Takachiyo 
Published: July 2006

Abstract
We have studied the catalytic activities of various substituted 2-pyridones on the mutarotation of 2,3,4,6-tetra-O-methyl-d-glucose (TMG). The results in an acetone solution at 37 °C showed that an introduction of the polar substituents into the 5- or 6-position, regardless of the nature of the substituents, retarded the relative rate of the mutarotation as compared to a parent compound, while that of alkyl substituents accelerated such rates. Further striking rate enhancements were observed in 5,6-dimethyl-substituted derivatives. Based on experimental results, we concluded that the 2-pyridones which can act as an effective catalyst are such that the 2-pyridone tautomeric form predominantly exists in solution due to its greater association ability and that the 2-pyridinol tautomeric form is energetically more stable for a lower activation energy of the double-proton transfer process in the 2-pyridone-TMG complex.