Bis(hfac)-copper(II) complexes bridged by pyrimidines showing magnetic interactions.

Crystals of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)bispyrimidinecopper(II) (1), bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)bis(4-methylpyrimidine)copper(II) (2), bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)bis(quinazoline)copper(II) (3) showed ferromagnetic interactions at extremely low temperature. Crystal structure analyses revealed that these complexes were catena-bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)[mu-pyrimidine-N(1):N(3)]copper(II), [Cu(hfac)(2)(pm)(2)](n), catena-bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)[mu-4-methylpyrimidine-N(1):N(3)]copper(II), [Cu(hfac)(2)(4-Me-pm)](n), and catena-bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)[mu-pyrimidine-N(1):N(3)]copper(II), [Cu(hfac)(2)(qz)](n), for (1), (2) and (3), respectively. In (1) and (2) the pyrimidines bridge the Cu atoms with an axial-equatorial mode to form one-dimensional spiral chains. Complex (3) also forms a one-dimensional chain structure. The coordination mode of (3) is axial-axial at room temperature, while axial-equatorial at 120 K. On the other hand, the structure of the other modification of the 4-methylpyrimidine complex (4), showing paramagnetic properties, was revealed to be a trinuclei complex bridged by two 4-methylpyrimidines, tris[bis-(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II)][bis-mu-4-methyl-pyrimidine-N(1):N(3)]. The chain structures with an axial-equatorial coordination mode of the bridging organic moieties should play an important role in the appearance of the ferromagnetic interactions.

Solid state optical activity of dichalcogenides: isolation by chiral crystallization and determination of absolute configuration.

[reaction--see text] Optically active diphenyl dichalcogenides were isolated in bulk for the first time by chiral crystallization. The absolute configuration of the P-helical enantiomer of diphenyl disulfide was determined by X-ray crystallography. On the basis of this determination and considering the similarities of the Cotton effects of diphenyl diselenide and ditelluride, the absolute configuration of optically active diphenyl dichalcogenides could be assigned. Furthermore, stereochemistry of chiral crystallization could be controlled by using an optically active crystal as a seed crystal.

Two-component molecular crystals from N-heteroaromatics and nitrobenzoic acids.

Five two-component molecular crystals, benzimidazolium 3-nitrobenzoate, C(7)H(7)N(2)(+).C(7)H(4)NO(4)(-), (I), benzimidazolium 4-nitrobenzoate, C(7)H(7)N(2)(+).C(7)H(4)NO(4)(-), (II), 1H-benzotriazole-3-nitrobenzoic acid (1/1), C(6)H(5)N(3).C(7)H(5)NO(4), (III), imidazolium 3-nitrobenzoate, C(3)H(5)N(2)(+).C(7)H(4)NO(4)(-), (IV), and imidazolium 4-nitrobenzoate, C(3)H(5)N(2)(+).C(7)H(4)NO(4)(-), (V), were prepared with the aim of making chiral crystals. Only (I) crystallizes in a chiral space group. The molecules of (I) and (II) are linked by hydrogen bonds to form 2(1) spiral chains. In (III), (IV) and (V), macrocyclic structures are formed from two acid and two base components, by an alternate arrangement of the acid and base moieties.

Radical-copper wheels: structure and magnetism of hexanuclear hybrid arrays.

Complexation of copper(II) bromide and chloride with 4-pyrimidinyl nitronyl nitroxide (4PMNN) as a bridging ligand gave discrete hexanuclear complexes carrying 12 spins, [CuX(2).(4PMNN)](6) [X = Br (1), Cl (2)], which crystallize in a trigonal space group. The crystallographic parameters are C(11)H(15)Br(2)CuN(4)O(2).0.3H(2)O, a = 28.172(2), c = 12.590(2) A, V = 8653(2) A(3), and Z = 18 for 1, and C(11)H(15)Cl(2)CuN(4)O(2).0.3H(2)O, a = 28.261(2), c = 12.378(1) A, and Z = 18 for 2. The hexanuclear arrays construct a perfect column perpendicular to the molecular plane. The diameter of the resultant honeycomblike channel is ca. 11.5 A defined by the interatomic distance of two opposing copper ions. Their magnetic behavior is interpreted as the simultaneous presence of ferro and antiferromagnetic couplings. The ferromagnetic couplings are attributed to the interactions between a copper spin and the axially coordinated nitronyl nitroxide spin and between nitronyl nitroxide groups through van der Waals contacts. The antiferromagnetic coupling is due to the interaction between copper ions across the pyrimidine bridges.

Dipyrimidine-copper(II) dinitrate complexes showing magnetic interactions.

Crystals of Cu(II)(NO(3))(2)(pm)(3) (1), and two crystalline forms of Cu(II)(NO(3))(2)(H(2)O)(2)(pm)(2), (2) and (3), showed ferromagnetic, antiferromagnetic and paramagnetic interactions at extremely low temperatures, respectively. Crystal structure analyses revealed that the complexes were catena-dinitrato[mu-pyrimidine-kappaN(1):kappaN(3)]-(pyrimidine-N(1))copper(II), [Cu(NO(3))(2)(pm)(2)](n), catena-diaquadinitrato[mu-pyrimidine-kappaN(1):kappaN(3)]copper(II), [Cu(NO(3))(2)(H(2)O)(2)(pm)](n), and diaquadinitratodipyrimidinecopper(II), Cu(NO(3))(2)(H(2)O)(2)(pm)(2) for (1), (2) and (3), respectively. In (1) the Cu atom is coordinated by the two nitrates and N atoms of the non-bridging pyrimidine and bridging pyrimidine to form a one-dimensional coordination polymer. The complex is a five-coordinated square pyramid and can be regarded as a pseudo-seven-coordinated complex, since other short non-bonding Cu.O contacts are observed. In the crystals of (2) the pyrimidine bridges the Cu atoms to form a one-dimensional coordination chain. On the other hand, complex (3) is not a coordination polymer. It is important to form a coordination polymer for the appearance of the magnetic interactions. Types of coordination of the bridging organic moieties should also play an important role in magnetic properties. Magnetic measurements of (1) and (2) show that they are good examples of uniform S = 1/2 ferro- and antiferromagnetic Heisenberg chains with exchange parameters 2J/kB = +1.8 and -36 K, respectively.

[Generalized tonic-clonic seizure induced by propofol in a patient with epilepsy].

A 47-year-old female was scheduled for ulnar osteotomy under general anesthesia combined with brachial plexus block. She had a history of symptomatic epilepsy due to subarachnoid hemorrhage. Immediately after giving 100 mg bolus of propofol to the patient, she developed generalized convulsion similar to a grand mal. The seizure was suppressed by the administration of thiamylal. After that no further convulsive attack occurred. Although it has been known that propofol has anticonvulsive properties, there have been several reported cases of seizure following the administration of propofol. Further studies are needed to clarify the mechanism of seizure induced by propofol in the patients with epilepsy.

Chemo- and stereoselective monobenzoylation of 1,2-diols catalyzed by organotin compounds

A new facile method for monoacylation of diols has been developed. A variety of cyclic and acyclic diols, in particular 1,2-diols, were selectively monobenzoylated in good yields by the reaction with benzoyl chloride in the presence of a catalytic amount of dimethyltin dichloride and inorganic bases such as potassium carbonate. Furthermore, the method was successfully applied to a kinetic resolution of racemic 1-phenyl-1,2-ethanediol using a chiral organotin catalyst. The ee was dependent on the kind of base, water as an additive, and the reaction temperature.

TEMPO radicals showing magnetic interactions. I. 4-(4-Halobenzylideneamino)TEMPO and related compounds.

X-ray crystal structure analyses of the 4-(4-halobenzylideneamino)TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidyl-1-oxyl) radicals 4-(4-fluorobenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl, 4-(4-chlorobenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl, 4-(4-bromobenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl and 4-(4-iodobenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl, and other 4-Ar-CH=N-TEMPO [Ar = 4-Ph-Ph, 2,2,6,6-tetramethyl-4-(4-phenylbenzylideneamino)piperidyl-1-oxyl, 4-Py, 2,2,6,6-tetramethyl-4-(4-pyridylmethylideneamino)piperidyl-1-oxyl, and 3,5-diCl-Ph, 4-(3,5-dichlorobenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl] radicals have been performed at room temperature. Some of these radicals show intermolecular ferromagnetic interactions at extremely low temperatures. X-ray analysis revealed that crystals of the 4-I-Ph derivative showed two modifications [(a) and (b)]; measurements of the magnetic properties of these crystals showed a ferromagnetic transition at an extremely low temperature for modification (a) and an antiferromagnetic interaction for modification (b). The structural features of these TEMPO radical crystals can be classified into three groups: (i) the crystal structures of the 4-Cl-Ph, 4-I-Ph(a) and 4-Ph-Ph derivatives, which show a ferromagnetic transition; (ii) the structures of the 4-Br-Ph and 4-Py derivatives, which show a ferromagnetic interaction (straight theta > 0); (iii) miscellaneous: the antiferromagnetic 4-F-Ph and 4-I-Ph(b) derivatives (straight theta < 0) and the ferromagnetic 3,5-diCl-Ph (straight theta > 0) derivative. Sheet-like arrangements of O atoms and intra-sheet interactions through the CH(2) or CH(3) groups of the TEMPO rings are related to the mechanisms of the ferromagnetic interactions.

TEMPO radicals showing magnetic interactions. II. 4-(Benzylideneamino)-TEMPO and related compounds.

X-ray crystal structure analyses were performed on 4-(Ar-methyleneamino)-TEMPO radicals at room temperature (TEMPO = 2,2,6,6-tetramethylpiperidyl-1-oxyl): Ar = Ph [4-(benzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl], 4-MeS-Ph [2,2,6,6-tetramethyl-4-(4-methylthiobenzylideneamino)piperidyl-1-oxyl], 4-Me-Ph [4-(4-methylbenzylideneamino)-2,2,6,6-tetramethylpiperidyl-1-oxyl], 4-PhO-Ph [2,2,6,6-tetramethyl-4-(4-phenoxybenzylideneamino)piperidyl-1-oxyl], 4-MeSO(2)-Ph [2,2,6,6-tetramethyl-4-(4-methylsulfonylbenzylideneamino)piperidyl-1-oxyl], 3-Py [2,2,6,6-tetramethyl-4-(3-pyridylmethylideneamino)piperidyl-1-oxyl] and 2-Naph [2,2,6,6-tetramethyl-4-(2-naphthylideneamino)piperidyl-1-oxyl]. Structures of Ph and 4-Me-Ph derivatives were also determined at 100 K. Some of these crystals have been revealed to show intermolecular ferromagnetic interactions at an extremely low temperature. Structural features of crystals of Ph, 4-MeS-Ph and 3-Py derivatives, which show ferromagnetic interactions, are very similar to each other. In these crystals, O atoms are arranged to form a sheet. The ferromagnetic interactions are considered to be transferred through O.H van der Waals' interactions of the beta-H atoms of the neighboring TEMPO rings within the sheet. Between O.O sheets, the aryl groups are arranged in a herringbone manner. The crystal structure of the 4-Me-Ph derivative, which shows an antiferromagnetic interaction, is also pseudo-isostructural with those of Ph, 4-MeS-Ph and 3-Py derivatives, while the arrangement of the aryl groups is different. The packing mode of the crystals of the 4-MeSO(2)-Ph derivative, of which the Weiss constant straight theta is nearly zero, is very different from those of the other derivatives showing magnetic interactions. The fact that the crystal structure of the paramagnetic 4-MeSO(2)-Ph derivative does not show the O.O sheet structure accompanying the O.beta-H interactions indicates that the intermolecular ferromagnetic interactions through beta-H atoms within the O.O sheet are important for these TEMPO radical crystals.

[Regional cerebral blood flow and oxygenation following cervicothoracic sympathetic block].

Stellate ganglion block (SGB) is considered to increase blood flow to the governing area, but recent studies have shown the decrease of common carotid arterial blood flow in the unblocked side following SGB. We investigated the influence of SGB on bilateral cerebral blood flow and oxygenation using a regional oxygen saturation (rSO2) monitor, TOS-96 (TOSTEC, Japan). The changes of blood volume (hemoglobin index: Hb I) and rSO2 were measured in twenty adult patients who underwent SGB at the transverse process of the C 6 vertebra. Prior to the investigation, two sensors were calibrated and placed on either side of each patient's forehead in order to see the difference. There were significant increases in rSO2 and Hb I in the blocked side and decreases in rSO2 and Hb I in the contralateral side. These results suggest that blood flow in the blocked side following SGB increases with decreased blood flow in the unblocked side. Patients with cerebral vascular disease undergoing SGB might be at risk of a decrease in cerebral blood flow in the unblocked area.

Brain-derived neurotrophic factor-like immunoreactivity in the adult rat central nervous system predominantly distributed in neurons with substantial amounts of brain-derived neurotrophic factor messenger RNA or responsiveness to brain-derived neurotrophic factor.

Distribution of brain-derived neurotrophic factor-like immunoreactivity was investigated in the adult rat brain using two types of antibodies against peptides, V2 and V4, unique to the brain-derived neurotrophic factor. Western blot analysis showed that both antibodies specifically bound brain-derived neurotrophic factor, but not other neurotrophins, and that they recognized identical molecules of 18,000 mol. wt, but not the 14,500 mol. wt mass of mature form, in extracts from the rat hippocampus. Both antibodies recognized an identical precursor form (30,000 mol. wt) in lysates of COS7 cells transfected with brain-derived neurotrophic factor gene. These indicated that both antibodies predominantly recognized identical precursor protein(s) or its derivative(s) probably because of their much higher amounts than the amount of mature protein. Immunochemical studies showed that anti-V2 predominantly stained the cytoplasm of cells; whereas the anti-V4 bound to the nucleus, suggesting that the tertiary structure of immunoreactive molecules changed depending on their location. Cell populations with the immunoreactivity were similar in most brain sections stained with either anti-V2 or anti-V4 antibodies. These results suggest that brain-derived neurotrophic factor-like immunoreactivity distributes, in most cases, in neurons responding to brain-derived neurotrophic factor and in neurons expressing abundant brain-derived neurotrophic factor messenger RNA. These, taken together with other results concerning distributions of messenger RNAs of brain-derived neurotrophic factor and TrkB, provide additional information to elucidate the function of brain-derived neurotrophic factor in the rat central nervous system.