bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of magnetically responsive neurons in the marine molluscTritonia diomedea
Authors: Wang John H. , Cain Shaun D. , Lohmann Kenneth J.
Published: December 2002

Behavioral experiments have demonstrated that the marine mollusc Tritonia diomedea can use the Earth's magnetic field as an orientation cue. Little is known, however, about the neural mechanisms that underlie magnetic orientation behavior in this or any other animal. In previous studies, two neurons in the brain of Tritonia, known as LPd5 and RPd5, were shown to respond with enhanced electrical activity to changes in earth-strength magnetic fields. We report evidence that two additional neurons, known as LPd6 and RPd6, also respond with increases in electrical activity when the magnetic field around the animal is altered.

Anatomical analyses revealed that prominent neurites from the Pd6 cells are located within two ipsilateral nerves, pedal nerves 1 and 2. These nerves extend to the periphery of the animal and innervate tissues of the anterior ipsilateral foot and body wall. Electrophysiological recordings demonstrated that action potentials generated by the Pd6 cells propagate from the central ganglia toward the periphery. These results imply that the Pd6 cells play an efferent role in the magnetic orientation circuitry. Given that these cells contain cilio-excitatory peptides and that Tritonia crawls using ciliary locomotion, the Pd6 neurons may control or modulate cilia used in crawling, turning, or both.
Copepod feeding currents: flow patterns, filtration rates and energetics
Authors: van Duren Luca A. , Stamhuis Eize J. , Videler John J.
Published: December 2002

Particle image velocimetry was used to construct a quasi 3-dimensional image of the flow generated by the feeding appendages of the calanoid copepod Temora longicornis. By scanning layers of flow, detailed information was obtained on flow velocity and velocity gradients.

The flow around feeding T. longicornis was laminar, and was symmetrical viewed dorsally, but highly asymmetrical viewed laterally, with high levels of vorticity on the ventral side. The flow rate through the feeding appendages varied between 77 and 220 ml day-1 per individual. The morphology of the flow field ensured that water was entrained over the full length of the first antennae. These were kept out of areas with high velocity gradients that could interfere with distant mechano- or chemoreception.

The volume of influence, i.e. the volume of water around the foraging copepod, where shear rates were significantly higher than background levels,was calculated. Implications for encounter probability and mechanoreception are discussed. The average rate of energy dissipation within the copepod's volume of influence is several times higher than the levels of turbulent energy dissipation these animals are likely to encounter in their environment. Even in highly turbulent environments, adult T. longicornis will not experience very significant effects of turbulence.

Within the volume of influence of the copepods the energy dissipation due to viscous friction varied between 6.6×10-11 and 2.3×10-10W. Taking mechanical efficiency and muscle efficiency into account, this results in a total energetic cost of the feeding current of 1.6×10-9W per copepod. This value represents only a small percentage of the total energy budget of small calanoid copepods.
Escape from viscosity: the kinematics and hydrodynamics of copepod foraging and escape swimming
Authors: van Duren Luca A. , Videler John J.
Published: December 2002

Feeding and escape swimming in adult females of the calanoid copepod Temora longicornis Müller were investigated and compared. Swimming velocities were calculated using a 3-D filming setup. Foraging velocities ranged between 2 and 6 mm s-1, while maximum velocities of up to 80 mm s-1 were reached during escape responses. Foraging took place at Reynolds numbers between 2 and 6, indicating that viscous forces are considerable during this swimming mode. Inertial forces are much more important during escape responses, when Reynolds numbers of more than 100 are reached.

High-speed film recordings at 500 frames s-1 of the motion pattern of the feeding appendages and the escape movement of the swimming legs revealed that the two swimming modes are essentially very different. While foraging, the first three mouth appendages (antennae, mandibular palps and maxillules) create a backwards motion of water with a metachronal beating pattern. During escape movements the mouth appendages stop moving and the swimming legs beat in a very fast metachronal rhythm, accelerating a jet of water backwards. The large antennules are folded backwards, resulting in a streamlined body shape.

Particle image velocimetry analysis of the flow around foraging and escaping copepods revealed that during foraging an asymmetrical vortex system is created on the ventral side of the animal. The feeding motion is steady over a long period of time. The rate of energy dissipation due to viscous friction relates directly to the energetic cost of the feeding current. During escape responses a vortex ring appears behind the animal, which dissipates over time. Several seconds after cessation of swimming leg movements, energy dissipation can still be measured. During escape responses the rate of energy dissipation due to viscous friction increases by up to two orders of magnitude compared to the rate when foraging.
Visualization of modulatory effects of serotonin in the silkmoth antennal lobe
Authors: Hill Evan S. , Okada Koutaroh , Kanzaki Ryohei
Published: December 2002

A unique serotonin-immunoreactive neuron innervates every glomerulus of the contralateral antennal lobe (AL), the primary olfactory center, of the male silkmoth Bombyx mori. In order to examine the possible modulatory effects of serotonin in the AL, we utilized high-speed optical imaging with a voltage-sensitive dye combined with bath application of serotonin. We found that serotonin at 10-4moll-1 caused significant and reversible increases in the optical responses in both the macroglomerular complex (MGC) and the ordinary glomeruli (Gs) evoked by electrical stimulation of the antennal nerve. Optical responses in both the MGC and Gs were also significantly longer lasting following serotonin application. Serotonin exerted a significantly greater enhancing effect in the toroid glomerulus of the MGC than in the cumulus, and the effects of serotonin were also non-homogenously distributed in the Gs. Our results are evidence that serotonin acts in both the MGC and Gs to modulate the responses of neuronal populations.
Endothermic heat production in honeybee winter clusters
Authors: Stabentheiner Anton , Pressl Helga , Papst Thomas , Hrassnigg Norbert , Crailsheim Karl
Published: December 2002

In order to survive cold northern winters, honeybees crowd tightly together in a winter cluster. Present models of winter cluster thermoregulation consider the insulation by the tightly packed mantle bees as the decisive factor for survival at low temperatures, mostly ignoring the possibility of endothermic heat production. We provide here direct evidence of endothermic heat production by `shivering' thermogenesis. The abundance of endothermic bees is highest in the core and decreases towards the surface. This shows that core bees play an active role in thermal control of winter clusters. We conclude that regulation of both the insulation by the mantle bees and endothermic heat production by the inner bees is necessary to achieve thermal stability in a winter cluster.
Freezing survival and cryoprotective dehydration as cold tolerance mechanisms in the Antarctic nematode Panagrolaimus davidi
Authors: Wharton David A. , Goodall Gordon , Marshall Craig J.
Published: December 2002

The relative importance of freezing tolerance and cryoprotective dehydration in the Antarctic nematode Panagrolaimus davidi has been investigated. If nucleation of the medium is initiated at a high subzero temperature (-1°C), the nematodes do not freeze but dehydrate. This effect occurs in deionised water, indicating that the loss of water is driven by the difference in vapour pressure of ice and supercooled water at the same temperature. If the nematodes are held above their nucleation temperature for a sufficient time, or are cooled slowly, enough water is lost to prevent freezing (cryoprotective dehydration). However, if the medium is nucleated at lower temperatures or if the sample is cooled at a faster cooling rate, the nematodes freeze and can survive intracellular ice formation. P. davidi thus has a variety of mechanisms that ensure its survival in its harsh terrestrial Antarctic habitat.
Adaptive color vision in Pullosquilla litoralis (Stomatopoda,Lysiosquilloidea) associated with spectral and intensity changes in light environment
Authors: Cheroske Alexander G. , Cronin Thomas W. , Caldwell Roy L.
Published: December 2002

Some stomatopod crustacean species that inhabit a range of habitat depths have color vision systems that adapt to changes in ambient light conditions. To date, this change in retinal function has been demonstrated in species within the superfamily Gonodactyloidea in response to varying the spectral range of light. Intrarhabdomal filters in certain ommatidia within the specialized midband of the eye change spectrally, modifying the sensitivity of underlying photoreceptors to match the spectrum of available light. In the present study, we utilized Pullosquilla litoralis, a member of the superfamily Lysiosquilloidea that also has a wide depth range. Individuals were placed within one of three light treatments: (1) full-spectrum,high-intensity `white' light, (2) narrow-spectrum `blue' light and (3)full-spectrum, reduced-intensity `gray' light. After 3 months, the intrarhabdomal filters in Row 3 ommatidia of the midband in blue- and gray-light-treated animals were short-wavelength shifted by 10-20 nm compared with homologous filters in animals in white-light treatments. These spectral changes increase the relative sensitivity of associated photoreceptors in animals that inhabit environments where light spectral range or intensity is reduced. The adaptable color vision system of stomatopods may allow animals to make the best use of the ambient light occurring at their habitat regardless of depth. The major controlling element of the plasticity in lysiosquilloid stomatopod color vision appears to be light intensity rather than spectral distribution.
Auditory encoding during the last moment of a moth's life
Authors: Fullard James H. , Dawson Jeff W. , Jacobs David S.
Published: December 2002

The simple auditory system of noctuoid moths has long been a model for anti-predator studies in neuroethology, although these ears have rarely been experimentally stimulated by the sounds they would encounter from naturally attacking bats. We exposed the ears of five noctuoid moth species to the pre-recorded echolocation calls of an attacking bat (Eptesicus fuscus) to observe the acoustic encoding of the receptors at this critical time in their defensive behaviour. The B cell is a non-tympanal receptor common to all moths that has been suggested to respond to sound, but we found no evidence of this and suggest that its acoustic responsiveness is an artifact arising from its proprioceptive function. The A1 cell, the most sensitive tympanal receptor in noctuid and arctiid moths and the only auditory receptor in notodontid moths, encodes the attack calls with a bursting firing pattern to a point approximately 150 ms from when the bat would have captured the moth. At this point, the firing of the A1 cell reduces to a non-bursting pattern with longer inter-spike periods, suggesting that the moth may no longer express the erratic flight used to escape very close bats. This may be simply due to the absence of selection pressure on moths for auditory tracking of bat echolocation calls beyond this point. Alternatively, the reduced firing may be due to the acoustic characteristics of attack calls in the terminal phase and an acoustic maneuver used by the bat to facilitate its capture of the moth. Although the role of less sensitive A2 cell remains uncertain in the evasive flight responses of moths it may act as a trigger in eliciting sound production, a close-range anti-bat behaviour in the tiger moth, Cycnia tenera.
Mussel MAP, a major gonad-duct esterase-like protein, is released into sea water as a dual constituent of the seminal fluid and the spermatozoon
Authors: Torrado Mario , Paz María , Korochkin Leonid I. , Mikhailov Alexander T.
Published: December 2002

Our interest in the comparative analysis of male reproductive-tract esterases in different animal groups has led us to undertake a detailed study of the Mytilus galloprovincialis male-associated polypeptide (MAP)throughout the mussel gonad-duct tract and at spawning. The results of this work indicate that MAP is a major protein in M. galloprovincialissemen, with dual presence in both sperm cells and cell-free seminal fluid. Shortly after spawning, the released sperm mass is subdivided in diffused cloudy-like and thread-shaped `clots', in which a soluble-phase MAP may persist as long as the clots keep their compact form. Additional experiments involving the incubation of spawned spermatozoa at increasing Triton X-100 concentrations demonstrated that MAP is also strongly associated with sperm cells. These results were further validated by immunofluorescent staining,which revealed that MAP is localized in the mid-piece region of spawned spermatozoa. This unexpected finding raises the possibility that MAP may play a role in sperm fertility in bivalves. Using whole-mount histology and micromanipulation techniques, we studied the structural patterning of the mantle gonad-duct network and assessed the sampling of luminal contents from the ducts. Of particular interest is the observation that MAP content in the luminal fluid increases from the lumen of the spermatogenic tubules to that of the collecting gonad ducts, where MAP is detected at a very high concentration. These high levels may lead to a significant presence of MAP in semen and consequently to a prolonged survival of sperm spawned at sea. In addition, data related to the potential structural similarity between mussel MAP and esterase S of the Drosophila virilis ejaculatory bulb are presented and discussed. Finally, we show that the 64kDa protein of human semen reveals positive cross-reactivity with antibodies directed against Mytilus MAP and Drosophila esterase S. Taken together, the results reveal mussel MAP as the only esterase-like protein described so far whose distribution in the gonad and semen can be specifically associated with maturation, transport, emission and survival of spermatozoa outside.
Muscle fine structure may maintain the function of oxidative fibres in haemoglobinless Antarctic fishes
Authors: O'Brien K. M. , Skilbeck C. , Sidell B. D. , Egginton S.
Published: December 2002

Muscle fine structure and metabolism were examined in four species of Antarctic fishes that vary in their expression of haemoglobin (Hb). To determine how locomotory pectoral muscles maintain function, metabolic capacity, capillary supply and fibre ultrastructure were examined in two nototheniid species that express Hb (Notothenia coriiceps and Gobionotothen gibberifrons) and two species of channichthyid icefish that lack Hb (Chaenocephalus aceratus and Chionodraco rastrospinosus). Surprisingly, icefish have higher densities of mitochondria than red-blooded species (C. aceratus, 53±3% of cell volume; C. rastrospinosus, 39±3%; N. coriiceps,29±3%; G. gibberifrons, 25±1%). Despite higher mitochondrial densities the aerobic metabolic capacities per g wet mass,estimated from measurements of maximal activities of key metabolic enzymes,are lower in icefish compared to red-blooded species. This apparent incongruity can be explained by the significantly lower mitochondrial cristae surface area per unit mitochondrion volume in icefishes (C. aceratus,20.8±1.6 μm-1; C. rastrospinosus,25.5±1.8 μm-1) compared to red-blooded species (N. coriiceps, 33.6±3.0 μm-1; G. gibberifrons,37.7±3.6 μm-1). Consequently, the cristae surface area per unit muscle mass is conserved at approximately 9 m2g-1. Although high mitochondrial densities in icefish muscle do not enhance aerobic metabolic capacity, they may facilitate intracellular oxygen movement because oxygen is more soluble in lipid,including the hydrocarbon core of intracellular membrane systems, than in aqueous cytoplasm. This may be particularly vital in icefish, which have larger oxidative muscle fibres compared to red-blooded nototheniods (C. aceratus, 2932±428 μm2; C. rastrospinosus,9352±318 μm2; N. coriiceps, 1843±312μm2; G. gibberifrons, 2103±194μm2). These large fibres contribute to a relatively low capillary density, which is partially compensated for in icefish by a high index of tortuosity in the capillary bed (C. aceratus=1.4, N. coriiceps=1.1).
Serotonin regulates repolarization of theC. eleganspharyngeal muscle
Authors: Niacaris Timothy , Avery Leon
Published: December 2002

Caenorhabditis elegans feeds by rhythmically contracting its pharynx to ingest bacteria. The rate of pharyngeal contraction is increased by serotonin and suppressed by octopamine. Using an electrophysiological assay,we show that serotonin and octopamine regulate two additional aspects of pharyngeal behavior. Serotonin decreases the duration of the pharyngeal action potential and enhances activity of the pharyngeal M3 motor neurons. Gramine, a competitive serotonin antagonist, and octopamine have effects opposite to those of serotonin: gramine and octopamine increase action potential duration and suppress M3 activity. The effects of serotonin, gramine and octopamine on action potential duration are dependent on the pharyngeal motor neurons MC and M3. When the MC and M3 motor neurons are functionally defective, serotonin and octopamine do not regulate the action potential. Our data suggest that serotonin alters pharyngeal physiology to allow for rapid contraction—relaxation cycles. Reciprocal regulation of pharyngeal behavior by serotonin and octopamine provides a mechanism for adapting to the presence and absence of food, respectively.
Quantitative changes in yolk protein and other components in the ovary and testis of the sea urchin Pseudocentrotus depressus
Authors: Unuma T. , Yamamoto T. , Akiyama T. , Shiraishi M. , Ohta H.
Published: December 2002

Both male and female sea urchins accumulate the major yolk protein (MYP;the most abundant yolk granule protein in sea urchin eggs) in the nutritive phagocytes of immature gonads before gametogenesis. In this study,quantitative changes in MYP as well as in other biochemical components in the ovary and testis were examined in the course of gametogenesis in Pseudocentrotus depressus. Before gametogenesis, both the ovary and testis contained large quantities of proteins, lipids and polysaccharides. MYP reached about 80% of total protein in both sexes. In the testis, MYP decreased rapidly as spermatogenesis proceeded, and the fully mature testis contained little MYP; the levels of lipids and polysaccharides also decreased. In contrast, the levels of nucleic acids and proteins other than MYP increased markedly. In the ovary, MYP decreased gradually as oogenesis proceeded, and the fully mature ovary contained less than half of the initial amount of MYP. Polysaccharides also decreased, whereas proteins other than MYP increased. These results, taken together with those from other studies, suggest that MYP serves as a protein reserve that accumulates before gametogenesis and is used as material for synthesizing new substances constituting gametes in both male and female sea urchins.
Tissue-specific expression of inducible and constitutive Hsp70 isoforms in the western painted turtle
Authors: Scott Michelle Anne , Locke Marius , Buck Leslie Thomas
Published: December 2002

Expression of Hsp73 and Hsp72 in four tissues of the naturally anoxia-tolerant western painted turtle (Chrysemys picta) was investigated in response to a 24 h forced dive and following 1 h recovery. Of the tissues examined, brain and liver displayed approximately threefold and sevenfold higher basal Hsp73 expression than heart and skeletal muscle. Basal Hsp72 expression was relatively low in all tissues examined. After the 24 h forced dive and 1 h recovery, Hsp73 expression did not differ significantly from basal expression with the exception of liver, where expression decreased significantly after 1 h recovery. Hsp72 expression was unchanged in liver following a 24 h dive; however, it increased twofold in brain and threefold in heart and skeletal muscle. Dive-induced Hsp72 expression was found to correlate inversely with basal Hsp73 expression. Following 1 h recovery, Hsp72 expression was significantly elevated in all tissues above levels in dived animals. These data indicate a tissue-specific pattern of Hsp73 and Hsp72 expression in the western painted turtle during both unstressed and stressed conditions.
Preferred temperature of juvenile Atlantic codGadus morhuawith different haemoglobin genotypes at normoxia and moderate hypoxia
Authors: Petersen Maria Faldborg , Steffensen John Fleng
Published: December 2002

Atlantic cod Gadus morhua has polymorphic haemoglobin, which can be separated into two homozygous types, HbI-1 and HbI-2, and one heterozygous type HbI-1/2. The geographical distribution of Atlantic cod with the different haemoglobin types varies, with the HbI2 allele occurring at high frequency in northern regions, and the HbI1 allele dominant in warmer areas. To determine if temperature is a selective parameter in the distribution of the haemoglobin types, the preferred temperature of the homozygous genotypes HbI-1 and HbI-2 was measured. We found that HbI-2 cod preferred a temperature of 8.2±1.5°C while HbI-1 cod preferred 15.4±1.1°C, and this preference was significant. The effect of hypoxia (35% oxygen saturation) on the preferred temperature was also measured. Previous studies showed that the preferred temperature of fish decreases during hypoxia, and this was the case for HbI-1 cod, which preferred 9.8±1.8°C during hypoxia, whereas HbI-2 cod did not show this effect. The results indicate that environmental temperature changes will lead to a distributional change in the different haemoglobin types of Atlantic cod,global warming providing an advantage for HbI-1 cod. However, since HbI-1 cod prefer a low temperature under hypoxic conditions, a combination of increased water temperature and hypoxia could be unfavourable for Atlantic cod stocks.
Site-Selective Activation of RNA Leading to Sequence-Selective RNA Cutters
Authors: Komiyama Makoto , Kuzuya Akinori , Mizoguchi Ryo
Published: December 2002

New types of RNA cutters for site-selective scission are prepared by combining metal ions with oligonucleotides bearing an acridine. Both lanthanide(III) ions and various divalent metal ions (e.g., Zn(II), Mn(II), and Mg(II)) are used without being bound to any sequence-recognizing moiety. The modified oligonucleotide forms a hetero-duplex with the RNA, and activates the phosphodiester linkages in front of the acridine. As a result, these linkages are preferentially hydrolyzed over the others, even though the metal ions are not fixed anywhere. The scission is efficient under physiological conditions, irrespective of the sequence at the target site. Site-selective RNA scission is also accomplished by combining an oligonucleotide bearing an acridine at its terminus, another unmodified oligonucleotide, and a metal ion. In the proposed mechanism, the acridine pushes the unpaired ribonucleotide out of the hetero-duplex and changes the conformation of RNA at the target site for the sequence-selective activation.
Ab Initio Direct Molecular Dynamics Simulations and QM/MM Computations in Search of Organic Reaction Mechanisms
Authors: Yamataka Hiroshi , Aida Misako
Published: December 2002

Ab initio direct-MD simulations and combined QM/MM computations are the theoretical methods that are expected to play an important role in the study of organic reaction mechanisms in the near future. This account reviews recent achievements with these methods in mechanistic studies of organic reactions. In particular the focus is placed on proton transfer, SN1, SN2, and SN2/ET borderline reactions as illustrative examples. The direct-MD simulations revealed the importance of dynamics in controlling the reaction path, which can often be different from the minimum energy path on the potential energy surface. It was also demonstrated that the QM/MM computations could be a promising method to analyze reactions in solution.
Synthesis, Structure, and Photochemistry of 2,3,5,6-Tetrasilyl-1,4-benzoquinones and Related Compounds
Authors: Tsutsui Shinobu , Sakamoto Kenkichi , Ebata Keisuke , Kabuto Chizuko , Sakurai Hideki
Published: December 2002

2,3,5,6-Tetrasilyl- and 2,3,5,6-tetragermyl-1,4-benzoquinones were obtained by oxidation of the corresponding 1,4-dimetaloxybenzene derivatives with pyridinium chlorochromate. X-ray crystallographic analysis revealed that the quinone ring of 2,3,5,6-tetrakis(trimethylsilyl)-1,4-benzoquinone (1a) was distorted into a chair form. The deformed quinone ring allowed a σ(Cquinone-Si)–π* electronic transition in 1a. Photolysis of 1a resulted in an isomerization, creating a ketene derivative, 4-carbonyl-2,3,5,5-tetrakis(trimethylsilyl)-2-cyclopenten-1-one.
Hydration Structure of the Urea Molecule in Highly Concentrated Aqueous Solutions
Authors: Kameda Yasuo , Naganuma Hisashi , Mochiduki Kazuhide , Imano Masahiro , Usuki Takeshi , Uemura Osamu
Published: December 2002

Neutron diffraction measurements with 14N/15N and H/D isotopic substitution methods have been carried out on aqueous 15 mol% urea solutions, in order to obtain information on the hydration structure of the amino group within the urea molecule in concentrated aqueous solutions. The observed first-order difference function, 0HΔN(Q), and the N–H partial structure factor, aNH(Q), were analyzed by the least squares fitting procedure. The nearest neighbor N···O and N···H distances were obtained to be 2.92(1) Å and 3.42(1) Å, respectively. The average hydration number per one amino group was determined to be 2.0(1). The tilt angle between the N–H···O axis and the molecular plane of the hydrogen bonded water molecule is estimated to be 51(5)°.
The Water Activity of Aqueous Solutions in Equilibrium with Ice
Authors: Koop Thomas
Published: December 2002

A thermodynamic derivation is presented to show that the water activity of aqueous solutions in equilibrium with ice is independent of the nature of the solute. In addition, recent data of ice nucleation in MgCl2 solutions are compared to water-activity-based ice nucleation theory.
Adsorption of Methylene Blue onto Aluminum-Containing Mesoporous Silica Films Prepared by Rapid Solvent Evaporation Method
Authors: Yoshikawa Takahiro , Nakamura Tomoyuki , Kuroda Kazuyuki , Ogawa Makoto
Published: December 2002

The adsorption of methylene blue onto aluminum-containing mesoporous silica films was investigated. The mesoporous silica films were synthesized by rapid solvent evaporation method using tetramethoxysilane, aluminum tri(s-butoxide), and trimethyloctadecylammonium chloride as a silica source, alumina source and supramolecular template, respectively. Methylene blue was adsorbed effectively on the mesoporous silica films from solutions. The adsorbed amount increased with the increase in the aluminum content of the films, indicating that the added aluminum generated the adsorption sites (probably acidic sites) for methylene blue adsorption. The mesopore surface is not strongly acidic because the protonation of methylene blue did not occur. Adsorbed methylene blue exists as monomers in the mesopore. The dehydration of the films resulted in the aggregation of methylene blue, as evidenced by the visible absorption spectra.
Alkoxo-Bridged Dinuclear and Tetranuclear Copper(II) Complexes with Schiff-Bases Derived from Benzoylacetone and 1,n-Diamino-n′-hydroxyalkanes (n, n′ = 3, 2; 4, 2; and 5, 3)
Authors: Mikuriya Masahiro , Minowa Kenichi , Nukada Ryoji
Published: December 2002

Alkoxo-bridged copper(II) complexes with N,N′-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,3-diamino-2-propanol (H3bzacpro), N,N′-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,4-diamino-2-butanol (H3bzacbu), and N,N′-bis(1-methyl-3-hydroxy-3-phenyl-2-propen-1-ylidene)-1,5-diamino-3-pentanol (H3bzacpen), [Cu2(bzacpro)(CH3CO2)] (1), [Cu4(bzacpro)2(C2H5O)2] (2), [Cu2(bzacbu)(CH3CO2)] (3), [Cu4(bzacbu)2(CH3O)2] (4), [Cu4(bzacpen)2(CH3CO2)2] (5), and [Cu4(bzacpen)2O]·H2O (6) have been synthesized and characterized by measurements of the infrared and electronic spectra, and the magnetic susceptibilities. Single-crystal X-ray analyses revealed that 1 and 3 are dinuclear copper(II) complexes having a dinuclear core bridged by an alkoxo-oxygen atom of bzacpro or bzacbu and acetato-oxygen atoms, whereas 2, 4, 5, and 6 are tetranuclear copper(II) complexes composed of μ-alkoxo(bzacpro)-μ-ethoxo-, μ-alkoxo(bzacbu)-μ-methoxo-, μ-alkoxo(bzacpen)-μ-acetato-, and μ-alkoxo(bzacpen)-μ-oxo-bridged units, respectively. Magnetic-susceptibility data show that an antiferromagnetic interaction is operative within the dinuclear or tetranuclear core in 1–3, 5 and 6, whereas a ferromagnetic coupling is operative in 4. The crystal structures of the three Schiff-base ligands have also been elucidated.
Polymeric Manganese Carboxylato Compounds [{Mn[m-C6H4(COO)2](C5H5N)2}n] and [{Mn(3-C5H4NCOO)2}n] with One- and Three-Dimensional Extended Structures
Authors: Wang Wenguo , Ma Chengbing , Zhang Xiaofeng , Chen Changneng , Liu Qiutian , Chen Feng , Liao Daizheng , Li Licun
Published: December 2002

Two catena manganese carboxylato complexes [{Mn[m-C6H4(COO)2](C5H5N)2}n] (1) and [{Mn(3-C5H4NCO-O)2}n] (2) were synthesized and structurally characterized. Isophthalate together with pyridine as a capping ligand leads to a 1-D alternating chain structure of complex 1, while 3-pyridinecarboxylate (also known as nicotinate) results in a 3-D network of complex 2, implying an effect of the ligand on the dimensionality of the extended structure. Stretching vibration differences, Δ(νas−νs) < 200 cm−1, for the COO− groups of both complexes were observed to be consistent with the bridging and chelating coordination modes. The variable-temperature conductance of 1 displays a semiconductor feature. Magnetic exchange interactions were analyzed using models composed of Mn2(μ-COO)2 and Mn2(μ-acidate)2 moieties, exhibiting an antiferromagnetic coupling behavior for each complex through Mn2(μ-COO)2 moieties. The magnetic interaction in the Mn2(μ-acidate)2 moieties is negligible.
Highly Selective Luminescence Determination of Terbium at the Sub-ppb Level with Sulfonylcalix[4]arene-p-tetrasulfonate
Authors: Horiuchi Takayuki , Iki Nobuhiko , Oka Hiromi , Miyano Sotaro
Published: December 2002

The energy-transfer luminescence of complexes of Tb3+ with calix- (CAS), thiacalix- (TCAS), and sulfonylcalix[4]arene-p-tetrasulfonates (SO2CAS), in which four p-phenolsulfonates are jointed by –CH2–, –S–, and –SO2–, respectively, was applied to an ultratrace determination of the Tb3+ ion. Based on the complexation behavior of each calix ligand, a determination procedure was established. A time-resolved measurement was conveniently employed to separate the background fluorescence from the luminescence of the calix-Tb3+ complexes. An improved sensitivity was attained by sulfur-bridged calixes, TCAS and SO2CAS, as compared to CAS, owing to the photophysical properties of the Tb3+-complexes. The detection limits for Tb3+ ion by CAS, TCAS, and SO2CAS ligands were estimated to be 8.2×10−10 mol dm−3 (131 ppt), 2.0 × 10−10 mol dm−3 (32 ppt), and 2.3 × 10−10 mol dm−3 (37 ppt) at S/N = 3, respectively. In terms of the selectivity, the effect of diverse coexisting ions on the luminescence intensity of the Tb3+ complexes was studied. The luminescence of the TCAS complex was interfered by the presence of a 5-fold amount of other lanthanide ions, while that of the SO2CAS complex was more tolerant for those metal ions, allowing the presence of as much as 50 to 100-fold amounts. Also, 10 to 1500-fold amounts of other common ions were tolerated by using SO2CAS. Thus, SO2CAS was proved to be a practical reagent for determining the Tb3+ ion at the sub-ppb level.
Preparation and Properties of Tin(IV) Complexes with the Sulfur-Rich Dithiolate C3S5 and C8H4S8 Ligands and Their Oxidation
Authors: Akasaka Tenpei , Nakano Motohiro , Tamura Hatsue , Matsubayashi Gen-etsu
Published: December 2002

[NMe4]2[Sn(C3S5)3], [NBun4]2[Sn(C3S5)3], [NBun4]2[Sn(C8H4S8)3], [NEt4][Sn(Bun)(C8H4S8)2] and [NBun4][Sn(Ph)(C8H4S8)2] [C3S52− = 4,5-disulfanyl-1,3-dithiole-2-thionate(2−) ; C8H4S82− = 2-{(4,5-ethylenedithio)-1,3-dithiole-2-ylidene}-1,3-dithiole-4,5-ditholate(2−)] were prepared by reactions of Na2[C3S5] or Na2[C8H4S8] with SnCl4·5H2O, Sn(Bun)Cl3 and Sn(Ph)Cl3 in EtOH. [NBun4]2[Sn(C8H4S8)3] was oxidized by iodine or TCNQ in DMF/CH2Cl2 to give [Sn(C8H4S8)3], which exhibited an electrical conductivity of 3.2 × 10−2 S cm−1 (compacted pellet at room temperature). [NBun4]2[Sn(C3S5)3], [NEt4][Sn(Bun)(C8H4S8)2] and [NBun4][Sn(Ph)(C8H4S8)2] were oxidized by iodine or TCNQ in acetone or in DMF to afford (C3S5)2 and (C8H4S8)n. Crystal structures of [NMe4]2[Sn(C3S5)3], [NBun4]2[Sn(C3S5)3], [NBun4][Sn(Ph)(C8H4S8)2] and (C3S5)2 were determined by X-ray crystallography.
UV-Visible and 1H NMR Spectroscopic Studies on Direct Chelate Formation between Alkaline Earth Metal Ions and 1-(2-Pyridylazo)-2-naphthol or 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol in Acetonitrile
Authors: Hojo Masashi , Ueda Tadaharu , Inoue Akihiko
Published: December 2002

In acetonitrile, chelate formation between alkaline earth metal ions and 1-(2-pyridylazo)-2-naphthol (PAN = Hpan) in both the absence and presence of CH3SO3H and 1,1,3,3-tetramethylguanidine (1,1,3,3-TMG) was examined by means of UV-visible absorption and 1H NMR spectroscopy at room temperature. Upon the addition of 0.01 mol dm−3 or more of Mg(ClO4)2 to a 5.0 × 10−4 mol dm−3 PAN–MeCN solution, the solution color turned from yellow to red. The appearance of a new absorption band with two peaks at 500 and 535 nm indicated 1 : 1 chelate formation between Mg2+ and PAN; the equilibrium constant was evaluated to be 2.5 × 10−3 for the following reaction: Hpan + Mg2+  →← Mg(pan)+ + H+. The presence of an equivalent amount of the base, 1,1,3,3-TMG, enhanced the chelate formation reaction, while that of the acid (CH3SO3H) depressed the reaction remarkably. The 1H NMR results verified the above reaction scheme for Mg2+ and PAN. The interaction between the metal ions and PAN in acetonitrile decreased as Mg2+ > Ca2+ ≅ Sr2+ >> Ba2+. In the absence of the base, strange to say, direct chelate formation between Mg2+ and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) was much less than that for PAN; however, conversely, it was greater in the presence of a ten-fold amount of the base. The additional interaction between the second Mg2+ and the N-atom of the diethylamino group in 5-Br-PADAP was concluded to depress the chelate formation of the first Mg2+. The enhancement of the acidity of CH3SO3H (considerably weak acid in MeCN) by the addition of Mg(ClO4)2 inhibited not only the chelation, but also another interaction between Mg2+ and 5-Br-PADAP.
BF3-Promoted Aromatic Substitution of N-Alkyl α-Trifluoromethylated Imine: Facile Synthesis of 1-Aryl-2,2,2-trifluoroethylamines
Authors: Gong Yuefa , Kato Katsuya , Kimoto Hiroshi
Published: December 2002

The aromatic substitution of three representative N-alkyl trifluoromethyl imines 1a–c (R: a, benzyl; b, benzhydryl; c, methyl), obtained from primary alkyl amines and trifluoroacetaldehyde ethyl hemiacetal, was used to investigate the preparation of 1-aryl-2,2,2-trifluoroethylamines. In the presence of BF3·OEt2, the reaction of imine 1 with various aromatic compounds proceeded smoothly at room temperature, giving N-alkyl-1-aryl-2,2,2-trifluoroethylamines in moderate-to-high yields. Moreover, successful regioselective removal of N-benzyl and N-benzhydryl groups was achieved by hydrolysis in hydrochloric acid or by palladium-catalyzed hydrogenolysis.
Preparation of Functionalized Thianthrenes and Their Higher Related Compounds by Photolysis of Benzotrithiole Derivatives
Authors: Kimura Takeshi , Mizusawa Susumu , Yoneshima Akira , Ito Shinya , Tsujimura Kazuhiko , Yamashita Tetsuro , Kawai Yasushi , Ogawa Satoshi , Sato Ryu
Published: December 2002

6,9-Diethyl-1,2,3,4,5-benzopentathiepin (1) and 4,7-diethyl-1,2,3-benzotrithiole (2) were photolyzed by a 100 W high-pressure mercury lamp in dichloromethane under an argon atmosphere. These reactions produced 1,4,6,9-tetraethylthianthrene (3) by way of desulfurization, dimerization, and ring contraction reactions. Application of the photolysis was possible to 4,8-diethylbenzo[1,2-d : 4,5-d′]di[1,2,3]trithiole (6) and 4,7-diethyl-5,6-ethylenedithio-1,2,3-benzotrithiole (7). These reactions provided 1,4,6,9-tetraethyl[4,5-b : 4′,5′-i]di[1,2,3]trithiolothianthrene (8) with two trithiole rings and 1,4,6,9-tetraethyl-2,3 : 7,8-bis(ethylenedithio)thianthrene (10) with two ethylenedithio groups on both sides of thianthrene, respectively. The photolysis of 1,4,6,9-tetraethyl-7,8-bis(octylthio)[1,2,3]trithiolo[4,5-b]thianthrene (12) and 1,4,6,9-tetraethyl-7,8-ethylenedithio[1,2,3]trithiolo[4,5-b]thianthrene (15) gave higher related derivatives of thianthrene, 1,4,6,8,10,13,15,17-octaethyl-2,3,11,12-tetrakis(octylthio)-5,7,9,14,16,18-hexathiaheptacene (14) and 1,4,6,8,10,13,15,17-octaethyl-2,3 : 11,12-bis(ethylenedithio)-5,7,9,14,16,18-hexathiaheptacene (16), respectively. The electrochemical property of each thianthrene derivative was verified by cyclic voltammetry using silver nitrate as a reference electrode.
Synthesis of meso-Substituted Trimethine Cyanine Dyes and Evaluation of Their Sensitivities in Sensitized Photo-Polymerization
Authors: Kimura Masaru , Mitekura Hirofumi , No Tomoko , Suzuki Kazuyoshi
Published: December 2002

In order to evaluate the role of a substituent in sensitivity enhancement of meso-substituted trimethine cyanine dyes as sensitizers for photo-polymerization, we prepared a series of cyanine dyes, 3-ethyl-2-{3-(3-ethyl-3H-2-benzothiazolylidene)-2-[2-(4 or 3-X-phenyl)ethenyl]-1-propenyl} benzothiazolium iodide, 1a–k (a: X = p-NMe2, b: X = p-OMe, c: X = p-CH3, d: X = H, e: X = p-Cl, f: X = p-CF3, g: X = p-CN, h: X = p-NO2, i: X = m-OMe, j: X = m-CH3, k: X = m-Cl). The sensitivity for the photo-polymerization tends to be greater for substituents with greater electron-donating ability. In the series, the sensitivity of dye 1a was 2.1 mJ/cm2 higher than the other sensitivities. The sensitivities of dye 2 having a 2-(9-julolidinyl)ethenyl group was high: 1.5 mJ/cm2 and that of dye 3 having a 2-(9-julolidinyl)-1-methylethenyl group was the highest: 0.7 mJ/cm2, among all dyes tested here.
Preparation, Structure, and Photochemistry of 2-Disilanyl-1,4-benzoquinones
Authors: Tsutsui Shinobu , Sakamoto Kenkichi , Ebata Keisuke , Kabuto Chizuko , Sakurai Hideki
Published: December 2002

We synthesized 5-chloro- and 5-bromo-substituted 2-(pentamethyldisilanyl)-1,4-benzoquinones 1a and 1b, respectively. Their electronic absorption spectra showed significant intramolecular charge-transfer interaction between disilane and 1,4-benzoquinone moieties. The intramolecular σ(SiSi)–π* transition energies of 1a and 1b were lower than that of 2-(pentamethyldisilanyl)-5-t-butyl-1,4-benzoquinone (1c). X-ray crystallographic analysis of chloro-substituted derivative 1a revealed that the angle between the Si–Si bond and the quinone ring was 74° and also that the structure of 1a in the solid state was also advantageous for CT interaction. Photoreaction of 1a and 1b gave α-sila-m-quinonemethide derivatives 3a and 3b, respectively, which were trapped by acetone. Matrix isolation of 3a, 3b, and their 2-methyltetrahydrofuran-complexes were accomplished in glass matrixes.
Intramolecular C=O···B Interactions in o-Boron Substituted Benzaldehyde, Acetophenone, and Benzophenone
Authors: Toyota Shinji , Asakura Mitsuhiro , Sakaue Tatsuya
Published: December 2002

The title carbonyl compounds bearing a 4,4-diphenyl-1,3,2-dioxaborolan-2-yl group at the ortho position were prepared to compare the Lewis basicity of carbonyl-oxygen atoms. In the benzoyl and formyl compounds, the intramolecular C=O···B interactions are so weak that no significant changes were observed in the 13C and 11B NMR and IR spectra compared with the reference compounds. For the acetyl compound, the C=O stretching absorption was shifted to lower wavenumber by 18 cm−1 in the IR spectrum because of the coordination. The interaction energy could be estimated to be ca. 27 kJ mol−1 by the variable temperature 1H NMR measurement. These substituent effects are discussed from the viewpoints of Lewis basicity and the conformational stability of the carbonyl moieties with the assistance of the DFT calculations.
Intramolecular Charge-Transfer Polymers between Dithiafulvene and Pyridinium Units: Conjugative Effect through Saturated Polymethylene Chains
Authors: Naka Kensuke , Uemura Takashi , Chujo Yoshiki
Published: December 2002

New polymers containing an intramolecular charge-transfer (ICT) structure (pyridinium–dithiafulvene–pyridinium) in the main chain were prepared. UV–vis measurements of the polymers suggested that conjugative effects occur through saturated polymethylene chains, and that such effects are enhanced as the length of the spacer polymethylene chain decreases. Polyviologens showed small but similar conjugations in their UV–vis measurements. A PM3 calculation of 1,1′-(1,2-ethanediyl)bis(pyridinium) suggested that low-lying LUMO resulting from an interaction between the σ* of the ethylene unit and π* of the pyridinium moiety affords the conjugative effect. The PM3 calculations and the UV–vis results show that the incorporation of the ICT moiety in the polymeric framework increases the conjugative effect through the polymethylene chains. The redox and conducting properties of the ICT polymers were also investigated. Both studies gave some implications of the conjugative effects of the polymers.
Resolution of Enantiomers Using Sugar-Carrying Polyisocyanides as Chiral Stationary Phases for HPLC
Authors: Tsuchida Akiko , Hasegawa Teruaki , Kobayashi Kazukiyo , Yamamoto Chiyo , Okamoto Yoshio
Published: December 2002

3,5-Dimethylphenylcarbamate derivatives of α-/β-glucose and α-/β-galactose-carrying helical poly(phenyl isocyanide)s were used as chiral stationary phases (CSPs) for HPLC to estimate their chiral recognition abilities. CD spectroscopy suggested that the helix sense in these rigid helical polymers may be regulated by the chirality of the α- or β-anomeric center of the sugar moieties. Some 10 different types of racemates with functional groups were completely or partially resolved depending on the stereostructure of the pendant sugars. The enhanced chiral recognition ability is attributable to the three-dimensionally regulated sugar arrays along the helical backbone; that is, the CSP of the α-glucose-carrying helical poly(phenyl isocyanide) exhibited more effective enantioseparation than that of the corresponding flexible poly(N-phenylacrylamide). The CSPs of the galactose-carrying poly(phenyl isocyanide)s showed the resolving ability for broader racemates than those of the glucose-type poly(phenyl isocyanide)s. Especially, the CSP of the α-galactose-carrying poly(phenyl isocyanide) separated the largest number of racemates.
Triethylborane-Induced Radical Reaction of Alkynylgallium with α-Halo Carbonyl Compounds
Authors: Usugi Shin-ichi , Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro
Published: December 2002

Treatment of terminal acetylenes with butyllithium, followed by an addition of gallium trichloride, afforded the corresponding alkynylgallium reagents. The reaction of the resulting alkynylgallium with α-halo carbonyl compounds in the presence of triethylborane as a radical initiator provided β,γ-acetylenic carbonyl compounds in good yields.
One-Pot Synthesis of Chiral N-Protected-4-amino Functionalized But-2-enoates from α-Amino Acids Mediated by 1-Hydroxybenzotriazole
Authors: Athanasellis Giorgos , Gavrielatos Efstathios , Igglessi-Markopoulou Olga
Published: December 2002

A novel one-pot synthetic route to 4-acetylamino-2-cyano-3-hydroxybut-2-enoates in good yields (63–71%) is reported. An HPLC analysis of these compounds showed very good enantiomeric excesses (90–94%), justifying the success of our methodology to maintain the stereochemical integrity of the starting materials used.
Cycloaddition of o-Quinodimethanes Generated from 1,2-Bis(bromomethyl)benzenes by Constant-Current Electroreduction
Authors: Kise Naoki , Mimura Ryosuke , Ueda Nasuo
Published: December 2002

The constant-current electroreduction of 1,2-bis(bromomethyl)benzenes with dienophiles in NH4NO3–MeOH gave Diels–Alder cycloadducts in moderate-to-good yields.
Enantio-Differentiating Hydrogenation of 2-Octanone over Modified Nickel Catalysts Prepared by an In Situ Modification
Authors: Osawa Tsutomu , Ozaki Nobuyo , Harada Tadao , Takayasu Osamu
Published: December 2002

The enantio-differentiating hydrogenation of 2-octanone was carried out over a tartaric acid-modified reduced nickel catalyst. It was shown that the in situ modification of the Ni surface was available for the hydrogenation of 2-octanone in the presence of a large amount of pivalic acid in the reaction media. An optical yield of 74% was attained with the in situ modified reduced Ni catalyst.
Controlling the Oxygen-Sensitivity of 1-Pyrenedecanoic Acid Chemisorption Layer onto Anodic Oxidized Aluminium Plate
Authors: Fujiwara Yuki , Amao Yutaka
Published: December 2002

Controlling the oxygen-sensitivity of optical sensor using layers of 1-pyrenedecanoic acid and myristic acid co-chemisorbed onto anodic oxidized aluminium plate was attempted. The oxygen-sensitivity was controlled by varying the molar ratio of myristic acid to 1-pyrenedecanoic acid.
Double Elimination Protocol for Access to Unsymmetrical Di(phenylethynyl)benzenes
Authors: Orita Akihiro , Ye Fangguo , Doumoto Atsushi , Otera Junzo
Published: December 2002

For facile access to phenylene-ethynylenes, a new methodology for construction of unsymmetrically substituted di(phenylethynyl)benzenes has been established by taking advantage of double elimination protocol of α-sulfonyl aldolates.
Unique Three-dimensionally Expanded Nanoporous Structure Constructed with a Cu(I) and cis,cis-1,3,5-Triaminocyclohexane Having a 3-Fold Axial Symmetry
Authors: Arii Hidekazu , Saito Yamato , Funahashi Yasuhiro , Jitsukawa Koichiro , Masuda Hideki
Published: December 2002

Unique supramolecular crystal with a large macrocyclic channel structure has been prepared from the reaction of a [CuI(MeCN)4]SbF6 and cis,cis-1,3,5-triaminocyclohexane with a three-fold axial symmetry, whose channel is constructed from a distorted pseudofive-fold axial symmetric ring with a pore size of 5×12 Å2.
Novel Utilization of Impedance Measurement for Electrochemical Biosensing Aiming at Elimination of Influence by Interference Materials
Authors: Kuwabata Susumu , Hasegawa Hidefumi , Kano Kenji
Published: December 2002

Application of the ac impedance technique to the electrochemical glucose sensing allowed determination of glucose concentration without influence of a serious interference material, ascorbic acid.
Bilirubin Oxidase and [Fe(CN)6]3−/4− Modified Electrode Allowing Diffusion-controlled Reduction of O2 to Water at pH 7.0
Authors: Nakagawa Takaaki , Tsujimura Seiya , Kano Kenji , Ikeda Tokuji
Published: December 2002

An enzyme-modified electrode was prepared producing a diffusion-limited bioelectrocatalytic current for the reduction of O2 to water at neutral pH and at ambient temperature. The electrode used bilirubin oxidase as an enzyme and [Fe(CN)6]3−/4− as a mediator, both of which were immobilized on the surface of a glassy carbon electrode by electrostatic entrapment with poly-l-lysine.