bluuebunny/crossref_metadata_2025 huggingface dataset:
TheC. elegansMELK ortholog PIG-1 regulates cell size asymmetry and daughter cell fate in asymmetric neuroblast divisions
Authors: Cordes Shaun , Frank C. Andrew , Garriga Gian
Published: June 2006

In the nematode Caenorhabditis elegans, neurons are generated from asymmetric divisions in which a mother cell divides to produce daughters that differ in fate. Here, we demonstrate that the gene pig-1 regulates the asymmetric divisions of neuroblasts that divide to produce an apoptotic cell and either a neural precursor or a neuron. In pig-1 mutants,these neuroblasts divide to produce daughters that are more equal in size, and their apoptotic daughters are transformed into their sisters, leading to the production of extra neurons. PIG-1 is orthologous to MELK, a conserved member of the polarity-regulating PAR-1/Kin1/SAD-1 family of serine/threonine kinases. Although MELK has been implicated in regulating the cell cycle, our data suggest that PIG-1, like other PAR-1 family members, regulates cell polarity.
Theoretical Explanation of the Hydrogen Wave on a Platinum Single Crystal Electrode
Authors: Narumi Hideyuki
Published: June 2006

Voltammograms observed on basal planes of a Pt single crystal electrode in 0.1 M HClO4 were analyzed theoretically. Adsorbed hydrogen atoms were assumed to form 2-dimensional (111), (100), and (110) lattices. These lattices were treated by applying the Hückel method to an elementary domain consisting of 400 × 200 lattice points with periodic boundary conditions. Results explained the essential aspects of the butterfly at Pt(111) and the hydrogen waves at Pt(100) and Pt(110). The lateral interactions of the adsorbed hydrogen atoms were attractive in all cases and their values were estimated. The value at Pt(110) reproduced the previous one derived from the adsorption isotherm analysis. The square-shaped wave observed at Pt(111) in a potential range of 0.05—0.35 V was explained by an entirely different model for a freely moving particle. The analysis suggested that the square wave is due to electrons which move freely in the adsorption layer. The Hückel method was further applied to 3-dimensional lattices having 2 to 3 layers. Results suggested a striking effect of the absorbed hydrogen beneath the surface on the hydrogen wave.
Equation of State of Acetic Acid Derived by Molecular-Dynamics Simulations on a Rigid-Molecule Model
Authors: Kataoka Yosuke , Matsumoto Mitsuhiro
Published: June 2006

The equation of state of an acetic acid fluid was derived by molecular-dynamics simulations on a rigid-molecule model. The optimized potential for liquid simulations (OPLS) given by Briggs, Nguyen, and Jorgensen was assumed. Only the Z form was adopted in the two conformers in order to save central processing unit (CPU) time to perform the molecular-dynamics simulation at many state points. Microcanonical simulations were performed for 729 states. The system had 256 molecules in the cubic basic cell. The equation of state was obtained by a least-squares fitting. The critical point and liquid-vapor phase boundary were compared with the observed values. Dimerization was also observed by 27 long runs in the gaseous phase around the liquid–vapor phase boundary. The main structure is hydrogen-bonded chains in the liquid phase. The excess entropy after subtracting the ideal gas term is −10R at low temperatures. This is compared with −8R in liquid water. These comparisons show that the present model can be used to simulate the hydrogen-bonded fluid of acetic acid.
Relationship between the π-Electron Distribution and the Symmetry of Cyclic C6H6 Systems
Authors: Ichikawa Hiroshi , Kagawa Hirotaka
Published: June 2006

In an attempt to comfirm the role of π electrons in benzene, the relationship between the π-electron distribution and the preferred symmetry in C6H6 systems was examined. It was shown that under the restriction of being planar, the C6H66+ system has a D6h geometry, which is fragile towards shrinking as well as a distortion, and is also fragile at saddle points towards bending. When π electrons are added to such a system, the π electrons distribute in the way of either D6h or D2h symmetry according to the number of electrons. When the π-electron distribution is D6h-symmetric, non-distortive (i.e., those along the A1g coordinate) forces are produced; when it is D2h-symmetric, distortive forces, i.e., those that break the D6h symmetry, appear. Optimization leads to a symmetry which is pre-determined by the π-electron distribution. In this way, it was elucidated that π electrons in benzene have a tendency to form a uniform distribution.
Organic Metal with a High Oxidation State (+5/3), (TTM–TTP)(I3)5/3
Authors: Mori Takehiko , Misaki Yohji , Yamabe Tokio
Published: June 2006

The crystal structure of the title compound, where TTM–TTP is 2,5-bis [4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene, has been determined by X-ray analysis. The donors form a uniform stack, which is responsible for metallic conduction down to TMI = 20 K. The anions are composed of discrete I3− and an infinite chain of I3−. Each donor has anomalously large positive charge of +5/3.
Theoretical Study of Water-Exchange Reactions of Hexahydrated Divalent Cations in the First Transition Series: Relationship between Reaction Mechanism and Stability of Heptacoordinated Species
Authors: Tsutsui Yuko , Wasada Hiroaki , Funahashi Shigenobu
Published: June 2006

We studied the characteristics of model intermediary species on reaction pathways using the ab initio molecular orbital method in order to explain a change in the mechanistic behavior of the water-exchange reaction of hexahydrated divalent cations when the central elements were changed in the first transition series. Calculations show that the hexacoordinated species binding to the entering water in the second shell, the dissociative pentacoordinated species of scandium(II) and copper(II) ions, and the associative heptacoordinated species of scandium(II) ion are at local minima, whereas the heptacoordinated species of copper(II) ion is at a second-order saddle point. We also considered calcium(II) and zinc(II) ions in order to examine the correlation between the intermediary species and the reaction mechanisms. All of the intermediary species for calcium(II) and zinc(II) ions resemble those of scandium(II) and copper(II) ions, respectively. The dissociative mechanism can operate for both the calcium(II) and zinc(II) ions. The associative mechanism, however, can operate only for the calcium(II) ion, and the zinc(II) ion has no meaningful stationary point on the reaction path. We also considered the effect of the electronic structures on the reaction mechanisms. We conclude as the following: The dissociative mechanism is operative for a water exchange of all members of the first transition series. An associative mechanism is expected for the water-exchange reaction of the earlier members, which have stable heptacoordinated species. The possibility of the operation of the associative mechanism depends on the existence of appropriate associative heptacoordinated species.
Electron Transfer from Tetrathiafulvalenes to Photoexcited C70 Studied by Observing Transient Absorption in the Near-IR Region
Authors: Alam Maksudul M , Watanabe Akira , Ito Osamu
Published: June 2006

The photoinduced electron transfer between C70 and tetrathiafulvalene or bis(ethylenedithio)tetrathiafulvalene in polar and nonpolar solvents and their mixture has been investigated by nanosecond laser photolysis/transient absorption spectroscopy in the visible and near-IR regions. The transient absorption bands of the triplet state of C70 observed in polar solvents decayed upon addition of tetrathiafulvalenes accompanied by the appearance of the transient absorption bands of the radical anion of C70. In benzene, the quenching of the triplet state of C70 was observed without the appearance of the radical anion of C70 within a nanosecond laser pulse, suggesting a collisional quenching of the triplet state of C70 with tetrathiafulvalenes. The quantum yield for the formation of the radical anion via the triplet state of C70 was about 1 for tetrathiafulvalene in benzonitrile. The quantum yield decreased in less polar solvents. The back electron transfer rates were also evaluated in polar solvents.
A Resonance Light-Scattering Analysis of the Suprahelical Helixes of Nucleic Acids Induced by 5,10,15,20-Tetrakis[4-(trimethyammonio)phenyl]porphine
Authors: Huang Cheng Zhi , Li Ke An , Tong Shen Yang
Published: June 2006

This paper discusses the usefulness of resonance light-scattering spectroscopy (RLSS), which can be obtained by using an ordinary spectrofluorimeter, for the analysis of the suprahelical helixes of nucleic acids induced by 5,10,15,20-tetrakis[4-(trimethyammonio)phenyl]porphine (H2tapp). Depending on the acidity of the aqueous solution, the titled porphyrin has two species, [H2tapp]4+ and [H4tapp]6+. Both species can stack on appropriate conditions along the surface of nucleic acids in the mode of long-range assembly; and this leads to the formation of suprahelical helixes of nucleic acids. Enhanced resonance light-scattering signals can be observed for the porphyrin-induced suprahelical helixes of nucleic acids with the maximal resonance light scattering near to 432 nm for [H2tapp]4+ and near to 452 nm for [H4tapp]6+. The exciton splitting signals, which are generally associated with the aggregation of porphyrins, as described by molecular-exciton theory, are observed at 428 nm in the RLS spectra, analogous to the circular dichroism spectra when the molar ratio of [H2tapp]4+ to nucleic acids (R) is greater than 0.89. These results indicate that porphyrin–porphyrin interactions occur in the suprahelical helixes of nucleic acids.
Solvent Extraction of Anionic Silver(I) Thiocyanate Complex as Ion-Pairs with Tetrabutylammonium Ions into Chloroform and 4-Methyl-2-pentanone
Authors: Ohmiya Yasunobu , Dung Nguyen Thi Kim , Sekine Tatsuya
Published: June 2006

Solvent extraction of silver(I) from aqueous 1 mol dm−3 Na(SCN, NO3) solutions, where the thiocyanate ion concentration was higher than 1 × 10−3 mol dm−3 and pH was 3, into chloroform and into 4-methyl-2-pentanone (MIBK) was studied in the presence of tetrabutylammonium ions (tba+) at 298 K. The extraction equilibria of the ion-pairs, tba+SCN− and tba+NO3− into these solvents were also determined. The experimental data were well explained by extraction of tba+Ag(SCN)2− into chloroform and both tba+Ag(SCN)2− and Na+Ag(SCN)2− into MIBK and by formation of Ag(SCN)n1−n, where n was 2 to 4 in the aqueous phase. More than half of the initial amount of tba+ in the aqueous phase was extracted as tba+SCN− and tba+NO3−. The analysis of the extraction data of silver(I) should be made by taking the decrease in the tba+ concentration due to these extractions into account. No dissociation of the ion-pairs was found in chloroform but the extracted ion-pairs were partially dissociated in MIBK. In the presence of 1 × 10−3 mol dm−3 tba+ in the initial aqueous phase, the extraction of silver(I) was much better into MIBK than into chloroform under otherwise identical conditions. The extraction and dissociation constants of the above species and the stability constants of the anionic thiocyanate complexes of silver(I) in the aqueous phase were calculated.
The Photolyses of 2,6- and 2,4-Difluorohalobenzenes
Authors: Song Yong-Qi , Yuzuri Tomoaki , Suezawa Hiroko , Sakakibara Kazuhisa , Hirota Minoru , Nakada Masahiro
Published: June 2006

Photolyses of 2,6- and 2,4-difluorobromobenzenes in acetonitrile gave isomerized and brominated products in addition to 1,3-difluorobenzene produced by the dehalogenation. The reactions were compared with similar reactions of the corresponding chloro- and iodoarenes. In general, photolytic cleavage of the C–X bond of 2,6-difluorohalo(X)benzene was shown to proceed more easily than the corresponding 2,4-difluorohalo compound.
Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
Authors: Okano Tamon , Satou Yoshikazu , Tamura Motoshi , Kiji Jitsuo
Published: June 2006

Lanthanoid triisopropoxides are active catalysts for aldol reactions. Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures. Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields. The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation. In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide. Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
Conformational Behavior of Methyl (3R)-3-{[(3′R)-3′ -Hydroxybutanoyl]oxy}butanoate in Solutions: Effect of Intramolecular Hydrogen Bond
Authors: Li Jun , Uzawa Jun , Doi Yoshiharu
Published: June 2006

Methyl (3R)-3-{[(3′R)-3′-hydroxybutanoyl]oxy}butanoate (MHBOB) has been prepared as a model compound of the hydroxy terminal part of poly[(R)-3-hydroxybutanoate] [P(3-HB)]; the NMR assignments and conformational analyses of the compound are reported. The NMR assignments of MHBOB were made by means of two-dimensional pulsed field gradient 1H–1H COSY and 1H–13C HMBC (heteronuclear multiple-bond correlation) spectroscopy. The conformational behavior of MHBOB generated by rotation about two CH2–CH bonds was investigated in chloroform and in aqueous solution at various temperatures by analysis of vicinal coupling in the 500-MHz 1H NMR spectra. In both chloroform and aqueous solution, the monomer unit adjacent to the methoxy group was found to adopt a similar conformational distribution to that of the P(3-HB) polymer backbone, in which the trans and gauche conformers were predominant, while the another gauche conformer was suppressed to almost zero. On the other hand, the monomer unit adjacent to the hydroxy group had a different conformational distribution relative to that of the other monomer unit, due to the formation of an intramolecular hydrogen bond between hydroxy and carbonyl groups. In chloroform, only the gauche conformer was predominant at temperatures between −60 and 57 °C, and even the fraction of another gauche conformer was higher than that of trans conformer at low temperatures below 0 °C. In aqueous solution, the fraction of gauche conformer was also higher than that of trans conformer, suggesting the formation of the intramolecular hydrogen bond. However, the formation of the intramolecular hydrogen bond in aqueous solution was not so strong as that in chloroform.
New Kemp’s Diacid Derivatives Give Efficient Transport and Modifiable Selectivity for Alkaline Earth and Transition Metal Ions
Authors: Baldwin Bruce W , Hirose Takuji , Wang Zhen-He , Uchimaru Tadafumi , Yliniemelä Ari
Published: June 2006

New derivatives of 1,3,5-trimethyl-r-1, c-3, c-5-cyclohexanetricarboxylic acid (Kemp’s triacid) showed high efficiency for alkaline earth and transition metal ion transport through a chloroform liquid membrane. Simple syntheses from Kemp’s triacid or its geometric isomer provided chelating agents with a tripodal binding site for metal cations. The tripodal binding site consisted of r-1, c-3-diaxial carboxyl group and a c-5-amide, ester, or C-methyl group. Alkaline earth metal transport was quite variable and sensitive to c-5-group changes. For transition metal transport, c-5-amide diacids gave high total transport efficiency. For c-5-ester or C-methyl diacids, complexation of smaller divalent cations was decreased, resulting in increased selectivity for large cations.
A Theoretical Study of Dioxygen Activation on the Dicopper Enzyme Model
Authors: Yoshizawa Kazunari , Ohta Takehiro , Yamabe Tokio
Published: June 2006

Dioxygen activation on the dicopper enzyme model was studied using fragment molecular orbital (FMO), Walsh-diagram, and molecular orbital overlap population (MOOP) analyses within the framework of the extended Hückel method. A dicopper peroxo model complex with a μ-η2 : η2-O2 binding mode is distorted to a corresponding dioxo complex with a Cu2(μ-O)2 diamond core along an assumed reaction coordinate describing O–O bond cleavage. FMO and Walsh-diagram analyses have clarified the bonding and orbital interactions between the dicopper active site and dioxygen. While the πg* orbitals of dioxygen begin with two electrons, in the early O2 binding stages two other electrons are effectively transferred from the copper d-block orbitals to O2. Qualitative calculations show that O–O bond cleavage should proceed with no cost of activation energy on the dicopper active site of actual enzyme systems.
Rearrangement Approaches to Cyclic Skeletons. XII. Acid-Catalyzed Isomerization of Bicyclo[3.2.1]oct-6-en-2-ones into Bicyclo[3.2.1]oct-3-en-2-ones without Racemization
Authors: Uyehara Tadao , Inayama Toshihiro , Kobari Takanobu , Kimura Yuuko , Yoneta Noriko
Published: June 2006

The treatment of a bicyclo[3.2.1]oct-6-en-2-one (3) with Amberlyst® (H-15) in boiling benzene gave a mixture of bicyclo[3.2.1]oct-3-en-2-one (5) and bicyclo[2.2.2]oct-5-en-2-one (6). The ratio of 5 to 6 was influenced by the substituent at the C-1 position of the ketone 3. Chiral ketones 3 were transformed into the chiral α,β-unsaturated ketones 5 without racemization.
Synthesis and Structure of [6](1,4)Naphthalenophane and [6](1,4)Anthracenophane and Their Peri-Substituted Derivatives
Authors: Tobe Yoshito , Saiki Shinji , Minami Hirokazu , Naemura Koichiro
Published: June 2006

[6](1,4)Naphthalenophane (1a), [6](1,4)anthracenophane (2a), and their peri-substituted derivatives 1b, 1c, and 2b were synthesized from 8-bromo[6]paracyclophane (4) by a benzoannelation method. The 1H NMR spectral properties of 1b, 1c, and 2b as well as the X-ray crystallographic structure analysis of 1b indicate that their bridged aromatic rings are more distorted than those of the corresponding parent systems, 1a and 2a. Thermally reversible photochemical isomerization of 1b and 2b took place readily, giving the corresponding Dewar valence isomers, 10b and 11b.
Syntheses and Structures of Synthetic Carboxylic Ionophores Containing 2,3-Naphthylene Groups
Authors: Chikaraishi-Kasuga Noriko , Onoue Ken-ichi , Osawa Yutaka , Nakahama Seiichi , Ohashi Yuji , Yamaguchi Kazuo
Published: June 2006

Two derivatives of ω-hydroxy carboxylic ionophore 2-[[2-[2-[2-[2-[2-[2-[2-(2-hydroxyethoxy)phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]ethoxy]phenoxy]methyl]benzoic acid 1, 2-[[3-[2-[2-[2-[2-[2-[3-(2-hydroxyethoxy)-2-naphthyloxy]ethoxy]phenoxy]ethoxy]phenoxy]ethoxy]-2-naphthyloxy]methyl]benzoic acid 2 and 2-[[3-[2-[2-[2-[3-[2-[2-(2-hydroxyethoxy)phenoxy]ethoxy]-2-naphthyloxy]ethoxy]phenoxy]ethoxy]-2-naphthyloxy]methyl]benzoic acid 3, were prepared. Both compounds exhibited high K+ selectivity over Na+, as did 1. The structures of the Rb salt of 2 and the K salt of 3 were determined by single-crystal X-ray analyses. Both ionophores formed psuedocycles by a head-to-tail hydrogen bond between the hydroxy and carboxylato groups and enclosed each cation like the seam of a tennis ball to make lipophilic complexes. However, the three-dimensional structures of the two hydrophobic salts differed from each other in spite of the similarity of the primary structures, which might be due to the interaction of the aromatic rings.
Chiral Discrimination by 4-Chloro- and 4-Bromophenylcarbamates of Maltooligosaccharides in HPLC, NMR, and CD
Authors: Yashima Eiji , Sahavattanapong Pennapa , Yamamoto Chiyo , Okamoto Yoshio
Published: June 2006

4-Chloro- and 4-bromophenylcarbamates of maltooligosaccharides (n = 5, 6, and 7) were prepared and their chiral recognition abilities as a chiral stationary phase for HPLC were evaluated. The maltooligosaccharides carbamates exhibited a characteristic chiral recognition depending on the racemates and resolved several racemates in HPLC. The enantioselectivity as well as elution order of enantiomers on the maltooligosaccharide derivatives were similar to those on the corresponding amylose phenylcarbamte derivatives. The maltooligosaccharides also showed chiral discrimination for some racemates in NMR; the proton resonances of racemates, such as trans-stilbene oxide, benzoin, and 1,2,2,2-tetraphenylethanol were split into a pair of peaks due to the enantiomers. A good correlation between the NMR results and the chromatographic elution order was observed for most racemates. An enantiomeric guest, bilirubin, was also chirally discriminated by the maltooligosaccharides in chloroform to show an induced CD. The structures of the maltohexaose derivatives were examined by molecular mechanics and molecular dynamics simulations.
Formation of Glyoxylic Acid by Oxidative Dehydrogenation of Glycolic Acid
Authors: Ai Mamoru , Ohdan Kyoji
Published: June 2006

Iron phosphates with a P/Fe atomic ratio of 1.2 were found to be effective as catalysts for a vapor-phase oxidative dehydrogenation of glycolic acid to glyoxylic acid. The effects of the reaction variables on the conversion and selectivity were studied. The optimum reaction temperature was around 240 °C and the optimum feed rate of oxygen was in the range of 10 to 25 mmol h−1 when the feed rate of glycolic acid was 12.3 mmol h−1. The reaction was not affected by a variation in the feed rate of water vapor in the range of 86 to 480 mmol h−1. The selectivity to glyoxylic acid remained unchanged at 74 mol% with an increase in the conversion of glycolic acid up to 70%; the highest yield of glyoxylic acid was 56.5 mol% at the conversion of 80%.
Synthetic Studies on Polypropionate-Derived 4-Pyrone-Containing Marine Natural Products
Authors: Yamamura Shosuke , Nishiyama Shigeru
Published: June 2006

Synthesis of 4-pyrone derivatives by employing the mild cyclization is described. The DMSO–(COCl)2 and Ph3P–CCl4 conditions were appeared to accommodate a synthetic potential as proton equivalents. This study established the absolute configurations, and provided revisions of formerly proposed structures of highly oxygenated propionate derived 4-pyrones, such as ilikonapyrone, peroniatriols I and II, and onchitriols I and II.
The Mechanisms of Photochemical Reactions of o-Sulfobenzoic Imides
Authors: Ono Isao , Sato Shohei , Fukuda Kiyoshi , Inayoshi Tomoko
Published: June 2006

The photochemical processes of N-propyl-o-sulfobenzoic imide to the amides were investigated in ethanol and monocyclic aromatics, such as benzene, anisole, toluene, polymethylbenzenes, and benzonitrile. It was clarified that although both the S1 and T1 states took part in those photochemical reactions, the mechanisms were different in ethanol and those aromatics. The mechanism in ethanol is thought to involve hydrogen-atom abstraction from ethanol by a diradical formed after the extrusion of sulfur dioxide. The mechanism in aromatics involved an energy transfer from the singlet excited aromatic molecules to the sulfobenzoic imide and the addition of the resulting diradicals to the partner aromatics. Although the sulfobenzoic imide sensitized to a triplet state by acetophenone in benzene resulted as well in the formation of the arylated benzamide, this process was minor in comparison with the process via the S1 state. This was attributed to the triplet multiplicity of the diradical. The reactions of the sulfobenzoic imide with p-xylene and mesitylene were less predominant than those with toluene and anisole, which was attributable to a steric effect of plural methyl groups on the ring. The fact that no formation of the arylated benzamides took place in the case of benzonitrile could be explained by a strong inductitive effect of a cyano group of benzonitrile.
Ab Initio Study of the Isomers: HNNSi, HSiNN, and HNSiN
Authors: Ornellas Fernando R , Iwata Suehiro
Published: June 2006

We report on new structural, energetics, and vibrational frequency data for three isomers on the potential energy surface [H, Si, N, N] calculated at the UHF, MP2, and CCSD(T)/6-311G(2d) levels of theory. Similarly to SiNN, conventional methods fail to predict a thermodynamic stability for the isomer HSiNN. However, at the CCSD(T) level, the species HSiNN was found to lie 13.63 kcal mol−1 lower in energy than HNNSi; the isomer HNSiN was located 47.62 kcal mol−1 above the global minimum. After including the zero-point energy corrections, the isomer HSiNN becomes almost isoenergetic with its dissociation products HSi and N2; its detection might be likely only at low temperatures.
Semiconductor Photocatalysis. Part 22. Visible-Light Induced Photoreduction of CO2 with CdS Nanocrystallites — Importance of the Morphology and Surface Structures Controlled through Solvation by N,N-Dimethylformamide
Authors: Yanagida Shozo , Kanemoto Masashi , Ishihara Ken-ichi , Wada Yuji , Sakata Takao , Mori Hirotaro
Published: June 2006

Carbon dioxide (CO2) is reduced to CO on hexagonal CdS nanocrystallites (mean diameter of 4 nm) prepared in N,N-dimethylformamide (DMF) under visible-light irradiation with a quantum yield of 0.098 at λ = 405 nm in the presence of TEA as an electron donor. Solvation of the surface of CdS nanocrystallites by DMF or a related amide molecules should control the crystalline growth and stabilize the favorable morphology with a size quantization-effect. The effect of Cd2+ or H2S on CO production and the emission behavior, and the effect of electron donors suggest an important role of the surface structures of CdS–DMF for photo-induced electron transfer to CO2. The scope and limitation of the photoreduction of CO2 with semiconductor nanoparticles are discussed.
Structures of Tetrakis(t-butylammonium) Diperoxotetramolybdate(4−) and -tungstate(4−)
Authors: Ozeki Tomoji , Yamase Toshihiro
Published: June 2006

Hydrogen-bonded columnar structures have been observed in tetrakis(t-butylammonium) diperoxotetramolybdate(4−) (1) and -tungstate(4−) (2). 1, [(CH3)3CNH3]4[Mo4O12(O2)2], crystallizes in the tetragonal space group with a = 16.312(2), c = 6.352(1) Å, V = 1690.2(5) Å3, Z = 2. 2, [(CH3)3CNH3]4[W4O12(O2)2], crystallizes in the tetragonal form, , with a = 16.488(3), c = 6.349(2) Å, V = 1725.9(9) Å3, Z = 2. In each crystal, four t-butylammonium cations bridge two [M4O12(O2)2]4− (M = Mo, W) anions through hydrogen bonds to terminal and bridging oxo-ligands to make a columnar structure along the c axis.
Structure and NMR Behavior of Cobalt(III) Polyamine Complexes of α,ω-Alkylenediamine-N,N,N′,N′-tetramethylenetetraphosphonate in Aqueous Solution
Authors: Ichikawa Tomohide , Sawada Kiyoshi
Published: June 2006

The complex formation of α,ω-diaminopolyphosphonates (ethylenediamine- [H8edtmp], trimethylenediamine- [H8tdtmp] and hexamethylenediamine-N,N,N′,N′-tetramethylenetetraphosphonate [H8hdtmp]) with cobalt(III) polyamine complexes has been investigated by means of 31P NMR spectroscopy. The formation and protonation constants of the complexes and the 31P NMR chemical shifts of each protonated species were determined from the pH dependence of the 31P NMR signals. In any complexes, the nitrogen atom of the ligand is not coordinated to CoIII. The complex cis-[CoCl(en)2(NH3)]2+ forms a mononuclear O-monodentate complex and two types of binuclear bis(O-monodentate) complexes by a reaction with edtmp and tdtmp, and forms a mononuclear O-monodentate complex and a dinuclear bis(O-monodentate) complex with hdtmp. The complex cis-[CoCl2(en)2]+ forms a mononuclear O-monodentate complex and a mononuclear O,O-bidentate complex having an eight-membered chelate ring with edtmp and tdtmp, and forms a mononuclear O,O-bidentate complex and dinuclear bis(O-monodentate) complexes with hdtmp. In the case of the edtmp complexes, two iminodiphosphonate groups interact with each other: 1) an interaction between the nitrogen atoms of two imino fragments by a hydrogen bond (NH+···N) in a monoprotonated species and 2) an intramolecular interaction between the protonated nitrogen atom and phosphonate O− of another imino group (NH+···−OP) in triprotonated and tetraprotonated species.
Synthesis, Structure, and Properties of 2,2-Bis(2-pyrimidinylthio)-4,4,6,6-tetrachlorocyclotri(λ5-phosphazene)s. Insight into Bonding Mode
Authors: Jung Ok-Sang , Kim Yong Tae , Lee Hyun , Kim Kwan Mook , Chae Hee Kwon , Sohn Youn Soo
Published: June 2006

The reaction of hexachlorocyclotri(λ5-phosphazene), N3P3Cl6, with a series of pyrimidine-2-thiol in the presence of triethylamine in boiling tetrahydrofuran solution affords only a geminal isomer, N3P3(N–S)2Cl4 (N–S = 2-pyrimidinylthio (pms), 4,6-dimethyl-2-pyrimidinylthio (dmpms), and trifluoromethyl-2-pyrimidinylthio (fmpms)) in high yield. The molecular structures of N3P3(pms)2Cl4 (monoclinic P21/n, a = 7.686(2), b = 28.236(7), c = 8.760(2) Å, β = 99.87(2)°, V = 1873.2(8) Å3, Z = 4, R = 0.052) and N3P3(dmpms)2Cl4 (triclinic , a = 8.698(3), b = 9.630(3), c = 14.179(6) Å, α = 100.88(3), β = 92.83(3), γ = 103.84(3)°, V = 1126.9(7) Å3, Z = 2, R = 0.049) have been solved. The crystal structures disclose that the nitrogen atom of the 2-pyrimidinylthiol group significantly interacts with the phosphorus atom of the cyclotri(phosphazene) ring within the sum of the van der Waals radii (3.40 Å). The P…N intramolecular interaction of N3P3(dmpms)2Cl4 (P(1)–N(5), 3.109(4); P(1)–N(7), 3.126(4) Å) is considerably longer than that of N3P3(pms)2Cl4 (2.965(7), 2.986(7) Å). Although such a unique intramolecular interaction does not seem to be exactly retained in solution, the steric effects of the geminal bis-substituted ligands seem to hinder further substitution at other untouched phosphorus atoms. The formation of only a geminal isomer and its structure seem to be involved in the mechanism of the substitution reaction.
An Important Role of the One-Electron Reduction Nitrosyl Coordinated to Ruthenium. A Redox-Induced Oxygen Atom Transfer Reaction between the Nitrosyl and Adjacent Nitrite Moieties of {RuNO}7-Type Nitrosyl Complex
Authors: Ooyama Dai , Nagao Hirotaka , Ito Kyoko , Nagao Noriharu , Howell F Scott , Mukaida Masao
Published: June 2006

A facile redox-induced nitrito-to-nitro isomerization occurs in cis-[Ru(NO)(ONO)(bpy)2]2+ ({RuNO}6-type nitrosyl, bpy = 2,2′-bipyridine). At room temperature, the one-electron reduction species (cis-[Ru(NO·)(ONO)(bpy)2]+({RuNO}7)) changes immediately to cis-[Ru(NO·)(NO2)(bpy)2]+ ({RuNO}7), which can be converted to cis-[Ru(NO)(NO2)(bpy)2]2+ ({RuNO}6) by one-electron oxidation. The nitro species is an isomeric twin of the original nitrito species. A mechanistic investigation has established that, during the nitrito–nitro redox-induced rearrangement, an oxygen-atom transfer reaction proceeded between the nitrosyl and the adjacent nitrite ligands. Such a behavior could not be found in the thermally-induced nitrito–nitro rearrangement of the {RuNO}6-type nitrosyl complex mentioned above. The {RuNO}7-type nitrosyl complex appears to behave as a key intermediate species of the oxygen-atom transfer reaction.
Preparation, Characterization, and X-Ray Crystal Structures of μ-2,6-Dimethylpyridine-α,α′-diyl Iridium(III)–Rhodium(III) Complexes and the Structure of [Rh2Cl4(μ-CH2-py-CH2)(PPh3)2](CH2-py-CH2 = 2,6-Dimethylpyridine-α,α′-diyl) Reinvestigated
Authors: Yamasaki Kazuyuki , Saito Hiroaki , Tadokoro Makoto , Matsumoto Keiji , Miyajima Seiichi , Nakamura Yukio
Published: June 2006

2,6-Bis(chloromethyl)pyridine was oxidatively added to [IrCl(PPh3)3] to give cis(P,P)-[IrCl2(ClCH2-py-CH2-C,N)(PPh3)2] (ClCH2-py-CH2 = {2-(6-chloromethyl)pyridyl}methyl) (1a), of which the cycloiridated structure has been established by an X-ray analysis. Complex 1a further reacts with [RhCl(PPh3)3] to afford an Ir(III)–Rh(III) complex [IrRhCl2(μ-Cl)2(μ-CH2-py-CH2-C,N,C′)(PPh3)3](CH2-py-CH2 = 2,6-dimethylpyridine-α,α′-diyl) (3). Upon prolonged heating in toluene, 3 liberates one triphenylphosphine ligand and [IrRhCl2(μ-Cl)2(μ-CH2-py-CH2-C,N,C′)(PPh3)2] (4) is formed. X-Ray crystal structure determinations of 3 and 4 have revealed their dinuclear structures, in which the metals are connected by two Cl atoms and a CH2-py-CH2 group acting, in 3, as a κC (for Ir) : κC,κN (for Rh)-bridging ligand, while, in 4, as a κC (for Rh) : κC,κN (for Ir)-bridging ligand. The structure of the corresponding Rh(III)–Rh(III) complex, [Rh2Cl4(μ-CH2-py-CH2)(PPh3)2] (6), which was incorrectly assigned based on its NMR spectral data alone [Bull. Chem. Soc.Jpn., 68, 183 (1995)], has been revised by an X-ray analysis to be analogous to that of 4. Pseudooctahedral geometries at the κC-bonded Rh(III) centers of 4 and 6 are completed by unusually close Rh···HC(aryl) contacts of 2.79 and 2.75 Å, respectively. Complex 4 is static but 3 as well as 6 are fluxional in haloalkane solvents. Such a solution behavior of 3 is discussed in the light of the solid structures of 3 and 4.
Magneto-Structural Correlations in Phenoxo-Bridged Copper(II) Compounds
Authors: Emori Shuji , Orimoto Kenichi , Ohtsuka Yasunobu
Published: June 2006

The magnetic susceptibilities of compounds [Cu(4-XPhO)2(L)] (4-XPhOH = phenol, 4-nitrophenol, 4-chlorophenol; L = 1,2-diaminoethane, N,N,N′,N′-tetramethylethylenediamine) and [Cu(salaz)(RCOO)] (Hsalaz = 8-(2-hydroxyphenyl)-1,5- diazabicyclo[3.2.1]octane; R = CH3–, C2H5–, (CH3)3C–) were determined over the temperature range of 77—300 K, and compared with those for salicylideneaminato-bridged compounds. The correlation between their structures and exchange-coupling strength were formulated to indicate that the exchange couplings for phenoxo-bridged copper(II) systems were affected not only by the p character of the hybrid orbitals on the bridging oxygen atom, but also by the electronic effects of the substituents on the aromatic ring.
Additive Effect of Palladium on the Catalytic Activity of In/TiO2–ZrO2 for the Selective Reduction of Nitrogen Monoxide in the Presence of Water Vapor
Authors: Haneda Masaaki , Kintaichi Yoshiaki , Inaba Megumu , Hamada Hideaki
Published: June 2006

The additive effect of noble metals (Pt, Pd, Rh, and Ir) on the catalytic activity of In/TiO2–ZrO2 for the selective reduction of NO with propene in the presence of water vapor was investigated. Although NO reduction activity of In/TiO2–ZrO2 was inhibited drastically by coexisting water vapor, the addition of palladium was capable of depressing the retarding effect. The presence of both indium and palladium was necessary for the enhancement of NO reduction activity, and this was accounted for by a synergistic effect between palladium and indium. Optimum indium and palladium loadings were at 2—5 wt% and 0.005 wt%, respectively. It is suggested that the NO reduction on Pd/In/TiO2–ZrO2 by propene proceeds via the following consecutive steps: the formation of oxygenated intermediates by the reaction of propene with oxygen on palladium, a spillover of the intermediates from palladium to indium and reaction between the intermediates and NO2 to form N2 on indium.
Activation of a Gold Electrode for the Oxidation of l-Ascorbic Acid. Adsorbed Substrate as a Catalyst
Authors: Ando Isao , Chofuku Hiroshi , Ujimoto Kikujiro , Kurihara Hirondo
Published: June 2006

The simple electrochemical activation of a gold electrode for the oxidation of l-ascorbic acid was examined. A polycrystalline gold electrode was activated for the oxidation of l-ascorbic acid by positive sweeps within a narrow potential range in a sample solution. The activation mechanism was investigated by voltammetry and in situ electrochemical STM. The activation is ascribed to the coordinative adsorption of l-ascorbic acid on the gold electrode, where it behaves as a catalyst for the oxidation of l-ascorbic acid in bulk.
A Convenient Synthesis of 1,2-Dihydro-1,2,4-triazolo[3,2-b]quinazolin-9(1H)-ones and Their 1,2,4-Triazolo Derivatives
Authors: El-Hiti Gamal Abdel-Rahman
Published: June 2006

A range of 1,2-dihydro-1,2,4-triazolo[3,2-b]quinazolin-9(1H)-ones (3) has been synthesized in very good yields by the reaction of 3-amino-2-anilino-4(3H)-quinazolinone (1) with aromatics aldehydes in the presence of excess piperidine as a base. The 1,2,4-triazolo[3,2-b]quinazolin-9(1H)-ones could be obtained in very good yields by dehydrogenation of compounds 3 with thionyl chloride. Reaction of 1 with active methylene compounds (diethyl malonate and acetylacetone) resulted in the production of condensed products. These condensed products could be cyclized to 1,2,4-triazolo[3,2-b]quinazolin-9(1H)-one by heating above the melting point. Acetylation of 1 by acetic anhydride was found to be dependent on the reaction conditions. The acetyl derivative 3-acetamido-2-anilino-4(3H)-quinazolinone formed under mild conditions, while dimerization took place under strong conditions to give a pentacyclic compound in very good yield.
Laser Flash Photolysis in High Speed Photopolymer Coating Layers. II: Sensitization Mechanisms of Aminochalcone-Type Dyes with a Radical-Generating Reagent
Authors: Itoh Hiroki , Takada Akiomi , Kudo Hideaki , Yokoyama Hideki , Senda Yasuhisa , Urano Toshiyuki , Nagasaka Hideki
Published: June 2006

The sensitization mechanisms of three aminochalcone-type dyes with a radical-generating reagent: (E)-3-(9-Julolidinyl)-1-phenyl-2-propen-1-one (A), (E)-2-(9-julolidinyl)methylene-1-indanone (B), and (E)-2-(9-julolidinyl)methylene-1-tetralone (C) with 2,4,6-tris(trichloromethyl)-1,3,5-triazine (TRI), in poly(methyl methacrylate) film have been investigated by laser flash photolysis using a total reflection cell. The fluorescences of the dyes were efficiently quenched by TRI with static quenching distances, (RS)S, of 1.5, 1.4, and 1.3 nm for A, B, and C, respectively. The observed static quenching distances of the initial triplet absorptions of the dyes, (RS)T, were similar to those of the fluorescences. The values of (RS)T for A, B, and C, are 1.6, 1.6, and 1.5 nm, respectively. The triplet decay times of the dyes were inefficiently quenched with the rate, (kq)T, less than 106 mol−1 dm3 s−1. The results suggested that a static singlet sensitization is predominant in the photoinitiation systems.
Carbon–Hydrogen Bond Activation by Triruthenium Carbonyl Species during Carbon Monoxide Promoted Elimination of 4,5-Dihydroacenaphthylene from [(μ2 : η1 : η5-C12H10)Ru3H2(CO)7]: Implication of Reaction Intermediates
Authors: Nagashima Hideo , Suzuki Akihiro , Nobata Mitsuharu , Aoki Katsuyuki , Itoh Kenji
Published: June 2006

Oxidative addition of a vinylic C–H bond occurred during the CO-promoted elimination of 4,5-dihydroacenaphthylene (3) from [(μ2 : η1 : η5-C12H10)Ru3H2(CO)7] (2) in CH2Cl2. The product, [(μ3 : η1 : η2 : η2-C12H9)Ru3H(CO)9 ] (4), was isolated and characterized by spectroscopy and crystallography. The carbonylation of a deuterium-labelled complex, [(μ2 : η1 : η5-C12H8D2)Ru3D2(CO)7] (2-d4), under the same conditions as that from 2 to 3 in CH2Cl2 afforded 4,5-dideuterioacenaphthylene (3-d2) and [(μ3 : η1 : η2 : η2-C12H7D2)Ru3H(CO)9] (4-d2). The lack of incorporation of deuterium atoms into the ruthenium hydride in 4-d2 suggested that dissociation of D2 from the triruthenium moiety in 2-d4 induced the oxidative addition of the vinylic C–H bond. Further carbonylation of 4 did not occur under the same conditions as the reaction from 2 to 4, but gave 3 in moderate yields under higher CO pressure (8 atm) at 50—100 °C. These results suggest that 4 was not directly involved in the CO promoted elimination of 3 from 2, but was closely related to the actual intermediates. Possible reaction mechanisms are discussed.
NMR and UV Study of 1,1′-(α,ω-Alkanediyl)bis[thymine] and 1,1′-(α,ω-Alkanediyl)bis[uracil]
Authors: Itahara Toshio
Published: June 2006

Treatment of thymine or uracil with Br(CH2)nBr (n = 3—10) in the presence of t-BuOK gave 1,1′-(α,ω-alkanediyl)bis[thymine] or 1,1′-(α,ω-alkanediyl)bis[uracil] together with 1-(ω-bromoalkyl)thymine or 1-(ω-bromoalkyl)uracil. The structures of these products were determined on the basis of the coupling constants between 5- and 3-positions of uracil ring on the 1H NMR spectra. Molecular aggregation of the thymine and uracil rings of these compounds in aqueous solution was studied on the basis of their 1H NMR and UV spectra. A stacking interaction of the two thymine rings linked by shorter polymethylene chains such as trimethylene and tetramenthylene groups was observed.
Facile Preparation of Vicinal Allylsiloxy- and Vinylsiloxyhaloalkanes and Their Radical Cyclization Reaction
Authors: Shinokubo Hiroshi , Oshima Koichiro , Utimoto Kiitiro
Published: June 2006

Treatment of 2-(allyldimethylsiloxy)-1,1-dibromoalkane, which was easily prepared by an addition of aldehyde to an ethereal solution of (allyldimethylsilyl)dibromomethyllithium, with tributyltin hydride in the presence of catalytic amount of triethylborane afforded 1-oxa-2-silacycloheptane derivative selectively in good yield. On the other hand, cyclization of vinyldimethylsiloxy derivative resulted in a formation of 3-methyl-1-oxa-2-silacyclopentane. An addition of allyldiphenylsilanol to ethyl vinyl ether in the presence of N-iodosuccinimide provided 1-(allyldiphenylsiloxy)-1-ethoxy-2-iodoethane, which was also converted into a seven-membered ring product upon treatment with tributyltin hydride.
A Grignard-Type Addition of Allyl Unit to Carbonyl Compounds Containing a Carboxyl Group by Using BiCl3–Zn(0)–Allyl Bromide
Authors: Wada Makoto , Honna Munekazu , Kuramoto Yoshihiro , Miyoshi Norikazu
Published: June 2006

In the presence of BiCl3–Zn(0), nearly equimolar amounts of allyl bromide reacted with carbonyl compounds containing a carboxyl group to afford the corresponding homoallylic alcohols having a carboxyl group or the intramolecular dehydrated lactones in good yields.
Biscyanines Linked by a 1,8-Naphthylene Skeleton: Models of Polymethine Dye Aggregates
Authors: Katoh Takashi , Ogawa Keizo , Inagaki Yoshio , Okazaki Renji
Published: June 2006

Biscyanines linked by a 1,8-naphthylene skeleton (1), suitable model compounds for a study on polymethine dye aggregates, were prepared. Biscyanines, 1b and 1c, having methoxy and chloro substituents on the benzothiazole nuclei, respectively, were identified to be in syn conformation based upon X-ray crystallographic analysis and NMR spectroscopy. Their absorption maxima were found to be hypsochromically shifted compared to those of the 1-naphthyl substituted monocyanines (2). Only a biscyanine 1e having negatively charged sulfonato groups on the benzothiazole nuclei showed a bathochromic shift and was found to exist as an anti conformer. These spectral shifts were reproduced by the calculations with the INDO/S-CI method and are in agreement with those based upon the molecular exciton theory. The positive shifts of the reduction potentials of 1 compared to those of 2 are explained by the Coulombic and orbital interactions between the two cyanine moieties.
Asymmetric Allylation of Carbonyl Compounds with Tartrate-Modified Chiral Allylic Tin Reagents
Authors: Yamada Koji , Tozawa Takashi , Nishida Minoru , Mukaiyama Teruaki
Published: June 2006

Chiral allylating reagents, readily generated in situ from tin(II) catecholate [SnII(O2C6H4)], allyl halides, chiral dialkyl tartrates, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), reacted smoothly with aldehydes or reactive ketones at −78 °C in the presence of a catalytic amount of copper salts to afford the corresponding optically active homoallyl alcohols. Allylation of aromatic aldehydes and pyruvates by the present chiral tin reagents proceeded in high yields (81—99%) with high enantioselectivities (89—94%ee). In addition, both enantiomers of dimethyl citramalate were prepared from the allylation products of benzyl pyruvate.
Imidazolyl-Tailed Tetrakis(pivalamidophenyl)porphyrinatocobalt (II): An Efficient Oxygen Adsorbent Molecule
Authors: Nishide Hiroyuki , Suzuki Ayako , Tsuchida Eishun
Published: June 2006

A meso-tetrakis(α,α,α,α-o-pivalamidophenyl)porphyrinatocobalt(II) derivative bearing covalently-bound imidazole (Scheme 1, CoPim) was synthesized. Oxygen-binding to CoPim was rapid and reversible. The CoPim in the solid state chemically adsorbed oxygen (20 ml O2/g CoPim), which was ca. 40-times greater than the physical adsorption amount. The oxygen-binding lifetime of CoPim was longer than that for the corresponding porphyrinatocobalt(II) with an externally added imidazole. The efficiency of CoPim as an oxygen carrier was demonstrated by oxygen-enrichment from air using a pressure-swing adsorption experiment.
A Newly Designed Adsorbent Prepared from Hydroxyapatite Originating from Cattle-Bones for Chromatographic Separation of Albumin and Lysozyme
Authors: Akazawa Toshiyuki , Kobayashi Masayoshi , Kodaira Kohei
Published: June 2006

Functional spherical particles 5—30 μm in size were prepared by a spray-drying method with ultrasonic dispersion from hydroxyapatite (r-HAp) which was derived from bones of cattle. The liquid chromatographic characteristics for the separation of bovine serum albumin (BSA) and lysozyme from egg white (LSZ) on the r-HAp particles were investigated in comparison with those of stoichiometric hydroxyapatite (s-HAp) derived from reagents. The specific surface area (SAD), the crystallite size (CS), and the microstructure of the HAp’s particles were strongly influenced by the heat-treatment at 273—1073 K (designated by HAp(273—1073)) in a stream of water vapor. In liquid chromatography (LC) analysis with columns packed with the HAp powders, for r-HAp, mixed solutions of 0.5—2.0 mg cm−3 BSA and LSZ were sufficiently eluted using a linear molarity gradient of sodium phosphate buffers at 313 K. The resolutions (RS) of the proteins and the widths for each half of the chromatographic curves (WHB for BSA or WHL for LSZ) were sensitively varied in connection with SAD and CS. The optimal values of the LC operating parameters for all the HAp’s were evaluated as RS of r-HAp(673) and WHB and WHL of r-HAp(873).
Chemical Shift, Chemical Shift Anisotropy, and Spin-Lattice Relaxation Time in 89Y-MAS and -Static NMR of Yttrium Compounds
Authors: Harazono Toshie , Watanabe Tokuko
Published: June 2006

The chemical shift, the range of chemical shift anisotropy, and the spin-lattice relaxation times (T1) in Y2O3, Y3Al5O12, and Y2O2S have been measured by solid state 89Y (nuclear spin 1/2)-MAS and -static NMR. The static NMR data and T1 are reported for the first time. The range of chemical shift anisotropy was 1500—2400 Hz. This range was influenced more by the nature of the atom bound to Y than by the coordination number or the crystallographic symmetry of Y. Very long T1 values were obtained for Y2O2S (6.61 h) and Y2O3 (3.92 h at 24d site and 3.81 h at 8b site). On the other hand, the T1 value (1.10 h) of Y3Al5O12 is much shorter compared with those of Y2O2S and Y2O3. The next-nearest neighboring atom of Y in Y3Al5O12 is identified as Al, which has the nuclear spin 5/2 of 100% natural abundance. The most likely origin of significantly shorter T1 of Y3Al5O12 is a dipole–dipole interaction between 89Y and 27Al.
Cation Diffusion in MGaBr4 (M = Li, Cu, and Ag) Studied by 7Li, 63Cu, and 71Ga NMR, 81Br NQR, and Conductivity
Authors: Tomita Yasumasa , Yamada Koji , Ohki Hiroshi , Okuda Tsutomu
Published: June 2006

Cation diffusion in MGaBr4 (M = Li, Cu) was confirmed by measuring the temperature dependence of the 7Li and 63Cu NMR linewidths. The activation energies for the cation diffusion were determined to be 36 and 44 kJ mol−1 for LiGaBr4 and CuGaBr4, respectively. The activation energy for the reorientation of the GaBr4− anion in CuGaBr4 was evaluated to be 62 kJ mol−1 from 71Ga NMR. The cation diffusion was also confirmed for MGaBr4 (M = Cu, Ag) by observing a modulation effect on the 81Br NQR T1. As expected from the modulation effect of NQR, the ionic conductivity of AgGaBr4 was one order higher than that of CuGaBr4.