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Complex underground flow processes can occur in flooded mine workings. As the groundwater rebounds, outbreaks, flooding, and slope stability problems can occur where hydraulic pressures build up in less drained areas. A time-series statistical analysis was conducted to understand how exploited areas in an abandoned coalfield were connected and to calculate groundwater response times to rain events by spatially and temporally correlating piezometric levels and discharge rates. Ten years of flow rate and water level data were statistically analyzed for an abandoned coalfield in Liege (Belgium). Then, the results were compared to results from physically-based simulations (a 3D groundwater flow model) based on data from the first 2 years of monitoring. The statistical approach gives qualitative indications on the interconnections between the different areas of the coalfield, as well as on the storage capacity/transmissivity of the aquifer. Improved understanding of this hydrogeological behavior can be used to prevent post-mining accidents and assess the associated risks.

Concerns were expressed that postoperative written instructions following endodontic treatment are not available in the Dublin Dental University Hospital.Data was collected in three phases: retrospective analysis of clinical notes for evidence of the delivery of postoperative instructions; a randomly distributed questionnaire to patients undergoing root canal treatment prior to the introduction of a written postoperative advice sheet; and, another survey following introduction of the advice sheet.Some 56% of patients' charts documented that postoperative advice was given. Analysis of phase two revealed that patients were not consistently informed of any key postoperative messages. In phase 3 analysis, the proposed benchmarks were met in four out of six categories.Postoperative advice after root canal treatment in the DDUH is both poorly recorded and inconsistently delivered. A combination of oral postoperative instructions and written postoperative advice provided the most effective delivery of patient information.

New tetrazole compounds were synthesized and characterised by NMR and FTIR spectroscopy as well as by single crystal X-ray diffraction. We present in this paper mono- and ditetrazoles, which represent a versatile class of building blocks for the formation of mononuclear iron(II) complexes with monotetrazoles as terminal ligands as well as iron(II) coordination polymers with ditetrazoles as bridging ligands. Especially, the series of α,ω-bis[tetrazol-1-yl]-alkanes open the field of fascinating supramolecular structures with spin transition properties.

The reaction of the phenol-based ligand 4-methyl-2,6-bis{[(2-methylpyridyl)(2-methylthiophenyl)amino]methyl}phenol(Hpy2th2s), containing pyridine and thiophene substituents, with copper(II) chloride and bromide yields two new dinuclear complexes with the composition [Cu2(py2th2s)X3], where X = Cl or Br. In both complexes, the copper(II) ions are pentacoordinate and bridged by the deprotonated phenolate anion and by one halogen anion. Both complexes exhibit geometric asymmetry, as the coordination environment around one of the two copper ions is square-pyramidal, whereas the geometry around the other can be best described as a distorted trigonal bipyramid. The complexes were characterized by means of X-ray single-crystal diffraction, ligand field and EPR spectroscopy, mass spectrometry, and electrochemically. Magnetic susceptibility measurements indicate an antiferromagnetic coupling between the two metal centers (2J ≈ −200 cm−1). The interaction of the complexes with model substrates 3,5-di-tert-butylcatechol and tetrachlorocatechol is reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The phenol-based ligand Hpy2ald containing formyl, amine and pyridine functions reacts with copper(II) nitrate, copper(II) bromide and manganese(II) chloride to yield complexes with unexpected structures. In contrast to previously reported coordination compounds with similar ligands, the carbonyl group of the ligand in all complexes does not coordinate to the metal ions. The metal-to-ligand ratio is 2:1 in the case of the copper(II) nitrate complex and 1:1 in the case of the copper(II) bromide and manganese(II) chloride complexes. The copper(II) nitrate complex exhibits both donor-atom and coordination number asymmetry, as one copper ion is pentacoordinate with an N3O2 donor set, and the other one is hexacoordinate with an O6 donor set. In the latter two complexes, the phenol group of the ligand remains protonated and fails to bridge the two metal ions; instead it is semi-coordinated to only one metal ion. This results in the formation of mononuclear complexes in which copper(II) or manganese(II) ions have a distorted square-pyramidal surrounding. All complexes were structurally, spectroscopically and magnetically investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Crystal structure determination and analysis have been carried out for the two spin-crossover compounds [Fe(teeX)6](BF4)2 (teeX is haloethyltetrazole; X = I: teei; X = Br: teeb), in both their high-spin (near 300 K) and their low-spin states (T = 90 K), using high-resolution powder-diffraction data collected at the ESRF (Grenoble, France) and SPring8 (Japan) synchrotron radiation facilities. The structures of teei have been solved using various direct-space structure determination techniques (grid search, genetic algorithm and parallel tempering) and refined with the Rietveld method using geometrical restraints. In the case of teeb, a structural model was found but a full refinement was not successful because of the presence of a significant amount of an amorphous component. Analysis of the structures (space group P21/c, Z = 2) and diffraction data, and the absence of phase transitions, show the overall structural similarity of these compounds and lead to the conclusion that the gradual spin-crossovers are likely to be accompanied by small structural changes only.

The phenol-based compartmental ligand Hpy2ald contains a tridentate amino arm and a weak donor aldehyde group at the 2 0 and at the 6 0 positions of the phenol ring, respectively. This ligand reacts with cobalt(II) perchlorate, cobalt(II) tetrafluoroborate and manganese(II) perchlorate, yielding dinuclear complexes, where two metal ions are doubly bridged by two deprotonated cresolate moieties. The coordination environment around the metal ions is then completed to a very distorted octahedron by three nitrogen donor atoms from the pendant amino arm and the oxygen atom of the aldehyde group. The crystal structures of the complexes, their spectroscopic and magnetic properties are reported. 2003 Elsevier B.V. All rights reserved.

A novel dodecanuclear copper(II) complex [Cu12(tidhd)4(MeOH)8(CH3COO)8](MeOH)0.8 (Htidhd = 1,1,7,7-tetrakis(imidazol-2-yl)-2,6-diaza-1,6-heptadiene) with imidazolato and acetato bridging ligands was synthesized by reaction of polyimidazole 1,1,7,7-tetrakis(imidazol-2-yl)-2,6-diazaheptane (Htidahp) with copper acetate in a methanol solution. The complex crystallized in the triclinic space group P with a = 9.1204(1), b = 13.5139(2), c = 27.6925(5), α = 76.8006(6)°, β = 82.8066(7)°, γ = 76.4594(9)°, Z = 1. Structure analysis shows that the unit cell of the complex contains twelve copper(II) ions in three different coordination environments. The complex is centrosymmetric and the two hexanuclear units are linked by two μ3-acetate anions [the Cu1−Cu1a distance is 3.5507(7) A]. The magnetic superexchange interaction via the bridging imidazolate ligand appears to be the most important magnetic interaction in this complex. Magnetic susceptibility measurement vs. temperature in the range of 6−300 K were fitted to the parameters g = 2.05, Ja = −32.0 cm−1 and Jb = −5.45 cm−1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The novel mononuclear complex [Cu(teec)2(NO3)2] with teec=1-(2-chloroethyl)tetrazole, has been prepared from 1 equiv. copper(II) nitrate with 2 equiv. of teec. The X-ray structure shows the formation of a mononuclear complex with hexa-coordinated copper(II) ions. The teec ligands are positioned in trans orientation with a distorted axial geometry. Two of the CuO bonds of the chelating nitrate anions are significantly longer than the other two CuO bonds (1.99 vs. 2.48 A). Linear-chain packing of the mononuclear units is reflected in very weak, linear ferromagnetic chains with θ=0.30 K and C=0.44 cm3 K mol−1. The spectral properties are in accord with the structural and magnetic data.

A new family of iron(II) tetrafluoroborate and perchlorate spin-crossover compounds has been synthesised and is discussed. The iron(II) ion is surrounded by six 1-ethyltetrazole ligands, which are halogen-substituted on the C2 atom of the ethyl group. The spin-crossover temperatures T1/2 are high compared to the unsubstituted (1-alkyltetrazole)iron(II) complexes. The shape of the spin-transition curve (i.e. γHS vs. T) varies largely over the different complexes and appears to be influenced neither by the crystal packing, nor by the electronic effects. The temperature-dependent spin-transition behaviour has been studied by magnetic susceptibility and by 57Fe-Mossbauer spectroscopy. These data have been supported by temperature-dependent mid-range infrared spectroscopy: the thermally induced spin transition has been observed by direct monitoring of the aromatic C−H stretching frequency. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The magnetic and structural properties of three gradual spin transition monomeric compounds based on the cation [Fe(Hpt)3] 2þ (Hpt ¼ 3-(pyrid-2-yl)-1,2,4-triazole) are presented. The non-cooperative character of the spin-crossover in [Fe(Hpt)3](BF4)2·2H2 O( I) is evaluated in light of its calorimetric properties, which yielded the thermodynamic values DtrsH ¼ 5.81 kJ mol 21 and DtrsS ¼ 39.5 J mol 21 K 21 . The light-induced excited spin-state trapping effect is performed on [Fe(Hpt)3](BF4)2·2H2 O( I) and [Fe(Hpt)3](SO4)0.4(BF4)1.2·3H2 O( II), and the subsequent HS ! LS relaxations are studied. Their merely first-order kinetics are affected by disorder in the structure of both complexes, which appears in the presence of a distribution of activation energies. HS species can also be frozen-in in I by rapid cooling. Continuous irradiation is shown to induce only apparent light-induced thermal hysteresis effect in I and II, stemming from slow kinetics of relaxation with respect to the kinetics of measurement. q 2003 Elsevier Science Ltd. All rights reserved.

The new asymmetric dinucleating ligand 2-{[bis(2-pyridinylmethyl)amino]methyl}-4-methyl-6-{[(2-pyridinylmethyl)amino]methyl}phenol (Hpy3asym) has been designed in order to model the type-3 active site of the copper proteins. This phenol-based “end-off” compartmental ligand has one tridentate and one didentate arm attached to the 2- and 6-positions of the phenolic ring, respectively. A dinuclear copper(II) nitrate complex with this ligand [Cu2(py3asym)(H2O)1.5(NO3)2]NO3 has been obtained and structurally characterized. In this complex both copper ions have a distorted octahedral geometry and are endogenously bridged by the phenolic oxygen atom of the deprotonated ligand. The complex shows a donor-atom asymmetry that consists of an N3O3 donor set for the Cu1 ion and an N2O4 donor set for the Cu2 ion. The electrochemical, magnetic behavior and spectral properties of the complex are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The ligand 1,3-bis(pyrazol-1′-yl)propane (bpp) has been prepared by reacting 1,3-dichloropropane with two equivalents of pyrazole. After reaction of bpp with copper(II) tetrafluoroborate, three different compounds were obtained, two with CuII and one with CuI as cation, depending on the preparative method. The formation of single crystals of these compounds was only observed when 1-(3-chloropropyl)pyrazole (ppc) was present in the solution. The single-crystal X-ray structures of [Cu(bpp)2](BF4)2 and [Cu(bpp)2](BF4) show that bpp acts as a didentate chelating ligand to form an uncommon eight-atom chelate ring with the copper ion. Two polymorphs of the CuII complex were characterized. In each of them, the metal atoms possess a distorted tetrahedral geometry. In the copper(I) complex the metal center is present in a less-distorted tetrahedral coordination sphere. The spectroscopic properties of the compounds are in agreement with the structural data. Cyclic voltammetry measurements showed a redox wave at 0.92 V vs. Ag/AgCl. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The synthesis, optical and magnetic properties and the X-ray crystal structure of [Cu2(amp)2Cl4] (amp=5-aminomethyl-3-methylpyrazole), a new dinuclear chloro-bridged copper(II) compound, are described. Both copper ions are in a distorted square pyramidal N2Cl3 environment, with the apical position of the copper being occupied by the bridging chloride anion, which is equatorial to the other copper. An anti-ferromagnetic coupling of J=−9.4 cm−1 is found, with a rather large zJ′ value of −2.1 cm−1, which is probably due to the different pathways of interaction that exist between the coppers in the crystal lattice. The coppers within each dinuclear unit are connected by the chloride bridges (intra pathway), whereas the coppers from different dinuclear units in the lattice are connected by hydrogen bonds (inter pathway).

The spin-crossover complexes [Fe(teec)6](X)2 (with teec=1-(2-chloroethyl)-tetrazole and X=BF4, ClO4, PF6) possess two iron(II) sites each having a different spin-crossover behaviour. The magnetic behaviour of the complexes obtained by slow crystallisation differs strongly from those obtained by precipitation. This difference results in either a spin crossover of 50% (X=ClO4, crystalline), two gradual steps (X=BF4, PF6), or two steps, of which one is gradual and the other having a thermal hysteresis (X=ClO4 precipitated). Both 57Fe Mossbauer spectroscopy and magnetic susceptibility measurements have been recorded as a function of T. The crystal structure of [Fe(teec)6](BF4)2 has been determined using X-ray synchrotron powder diffraction. Of [Fe(teec)6](ClO4)2 only the cell parameters could be determined. The ligand field spectra of the low-spin and high-spin states clearly indicate a 1A1→5T2 spin transition with 10 DqLS/10 DqHS=1.72.

The synthesis and characterization of the spin transition compound hexakis(1-methyltetrazole-N4)iron(II) trifluoromethanesulfonate obtained from the reaction of 1-methyltetrazole and iron(II) triflate are described. The spin transition of [Fe(mtz)6](CF3SO3)2 (1) presents a hysteresis loop in magnetism with T↓=157.0 and T↑=179.5 K. Only one-third of the Fe(II) ions undergo this transition, the other two-thirds of the ions remain in the high-spin state. Mossbauer spectroscopy and relaxation studies have shown that the actual width of the hysteresis is only 12 K, with T↓=167.5 and T↑=179.5 K. Thermal spin-state trapping appears to be possible. The trapped high-spin state is stable up to 103 K. The relaxation is not first-order. After irradiation with red light, reverse light-induced excited spin state trapping (LIESST) is observed. The new low-spin state is stable up to 42 K. Also, its relaxation to HS is non-first-order. A reverse light-induced thermal hysteresis loop of approximately 7 K width is present too. No LIESST effect could be observed. Finally, a ferromagnetic type of coupling has been recognized, which is temperature and field dependent.

In [Fe(mtz) 6 ](BF 4 ) 2 (mtz=1-methyltetrazole), a spin transition of 50% of the Fe(II) ions corresponding to one crystallographic site occurs at 74 K. Thermal trapping in the HS state of the spin transiting site is achieved quantitatively. Relaxation back to the LS state occurs in the range 45–70 K. Non-first-order kinetics are reproduced using a phenomenological model including a self-acceleration parameter α =1.8. The Arrhenius plot shows that a thermally activated process is dominant in the range of temperatures studied, with an activation energy E a =6.02 kJ mol −1 . The speed of cooling and the applied field are shown to be of small influence on the kinetics. A new member of the propyltetrazole family, [Fe(ptz) 6 ](CF 3 SO 3 ) 2 ·2ptz (ptz=1-propyltetrazole), has been synthesized, which has two non-coordinated ptz molecules in the lattice. Its steep transition at 178 K is characterized by magnetic measurements, Mossbauer spectroscopy, reflectivity and calorimetry. The LIESST effect is shown to be present at 10 K, but only on the surface and with an extremely short lifetime.

The structure of the coordination compound [Fe(teec)6](BF4)2, hexa[1-(2-chloroethyl)tetrazole]iron(II) di(borotetrafluoride), has been determined using the grid-search techniques of the program suite MRIA. A Guinier-camera data set was used to determine the unit cell, the space group and to position the initial model. A high-resolution synchrotron powder data set was used to position a more detailed model using torsion-angle variation and to refine the structure leading to Rp = 0.0689, Rw = 0.0805 and GoF = 1.38. The crystal structure at room temperature shows the existence of two symmetry-equivalent iron(II) ions in the high-spin state.

The compounds hexakis(1-(2-chloroethyl)-tetrazole-N4)copper(II) tetrafluoroborate mono(1-(2-chloroethyl)-tetrazole) (1) and hexakis(1-(2-chloroethyl)-tetrazole-N4) copper(II) perchlorate mono(1-(2-chloroethyl)-tetrazole) (2) were obtained from the crystallization of 1-(2-chloroethyl)-tetrazole (teec) with the respective copper salt. The X-ray structures are reported. Both compounds crystallize in the monoclinic space group C2/c for 1: a = 25.754(3) A, b = 18.162(3) A, c = 10.298(2) A β = 104.294(7)° and Z = 4 and for 2: a = 25.745(3) A, b = 18.197(3) A, c = 10.29355(3) A β = 104.512(10)° and Z = 4. The CuII ions are octahedrally surrounded by six teec ligands. One free teec ligand is present in the structures. The Cu–N distances in the centrosymmetrical units are 2.01, 2.04, and 2.39 A in both compounds, consistent with a Jahn–Teller elongated octahedron. The ligand field spectra of both compounds show a signal in the visible range at about 15.200 cm−1 and by an EPR spectrum the following values are found: g| = 2.29 and g⊥ = 2.03. The compounds are both paramagnetic and the χ T value of 0.37 cm−1 K mol−1, which is associated with S = 1/2, is what would be expected for a mononuclear CuII complex.

The synthesis and characterization of tris[3-(pyridin-2-yl)-1,2,4-triazole]iron(II) bis(tetrafluoroborate), obtained from the reaction of 3-(pyridin-2-yl)-1,2,4-triazole (Hpt) and hexaaquairon(II) tetrafluoroborate, [Fe(H2O)6](BF4)2, is described, together with its crystal structures at two temperatures. X-ray crystallographic parameters are as follows: [Fe(Hpt)3](BF4)2·nH2O (n ≈ 2) at 250 K: orthorhombic space group Pbam, a = 15.8068(18) A, b = 17.2800(14) A, c = 21.215(2) A, V = 5794.7(10) A3, and Z = 8. [Fe(Hpt)3](BF4)2·nH2O (n ≈ 2) at 95 K: orthorhombic space group Pbam, a = 15.7080(12) A, b = 17.1023(16) A, c = 21.006(2) A, V = 5643.1(9) A3, and Z = 8. The FeII ions are (at both temperatures) octahedrally surrounded in a mer-configuration. The complex has been subjected to both 57Fe Mossbauer spectroscopy and magnetic susceptibility measurements. The 57Fe Mossbauer spectrum shows the presence of two different iron(II) sites. The high-spin fraction vs. T curve of the crossover, obtained by SQUID measurements, is gradual and without hysteresis, with T1/2 = 135 K.

Eccentric exercise may elicit damage to the contractile elements. This primary damage is followed by secondary changes, consisting of histological changes and changes in glycogen and energy metabolism. The mechanism underlying changes in glycogen homeostasis and energy metabolism is not well established. The aim of this study was to investigate the possible relationship between changes in adenine and guanine nucleotides, inosine monophosphate (IMP), creatine phosphate, glycogen content and histology in the rat tibialis anterior (TA) muscle after forced lengthening or isometric exercise. The right muscles were either forcibly lenghtened or isometrically exercised, while the contralateral muscles served as non-exercised controls. The exercised muscles were dissected 0, 6 and 24 h post-exercise and the contents of adenine and guanine nucleotides, IMP, creatine phosphate, and glycogen determined. In addition, histological changes were assessed. Immediately after both types of exercise increases in tissue IMP levels were found. Irrespective of the type of exercise, glycogen content was decreased immediately post-exercise, but restored 6 h postexercise. Twenty-four hours later a second decline in glycogen content was found after both types of exercise. In forcibly lengthened muscles ATP content was decreased 24 h post-exercise. In isometrically exercised muscles ATP was not decreased at any time. Gross structural changes were found in all forcibly lengthened muscles (9–12% of TA muscle volume). In isometrically exercised muscles structural changes were minor (up to 0.1 % of muscle volume), were found only immediately post-exercise and in only 4 out of 18 muscles. It is concluded that forced lengthening results in decreased ATP levels. Changes in glycogen homeostasis were found after both isometric exercise and forced lengthening, demonstrating that these changes are not strictly related to degenerative changes.

We have synthesized, crystallized, and studied the structural and electric transport properties of organic molecular crystals based on a rubrene derivative with $t$-butyl sidegroups at the 5,11 positions. Two crystalline modifications are observed: one (A) distinct from that of rubrene with larger spacings between the naphtacene backbones, the other (B) with an in-plane structure presumably very similar compared to rubrene. The electric transport properties reflect the different structures: in the latter phase (B), the in-plane hole mobility of $12\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}∕\mathrm{V}\phantom{\rule{0.2em}{0ex}}\mathrm{s}$ measured on single-crystal field-effect transistors is just as high as in rubrene crystals, while in the A phase, no field effect could be measured. The high crystal quality, studied in detail for B, reflects itself in the density of gap states: The deep-level trap density of as low as ${10}^{15}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}\phantom{\rule{0.2em}{0ex}}{\mathrm{eV}}^{\ensuremath{-}1}$ has been measured, and an exponential band tail with a characteristic energy of $22\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ is observed. The bulk mobility perpendicular to the molecular planes is estimated to be of the order of ${10}^{\ensuremath{-}3}--{10}^{\ensuremath{-}1}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}∕\mathrm{V}\phantom{\rule{0.2em}{0ex}}\mathrm{s}$.

The complex [Fe(teec)6](BF4)2 (teec = chloroethyltetrazole) shows a two-step complete spin-crossover transition in the temperature range 300-90 K. Time-resolved synchrotron powder diffraction experiments have been carried out in this temperature range, and crystal structure models have been obtained from the powder patterns by using the parallel tempering technique. Of these models, the low-spin state structure at 90 K has been refined completely with Rietveld refinement. Its structural characteristics are discussed in relation to the high-spin state model and other spin-crossover compounds. The complex shows a remarkable anisotropic unit-cell parameter contraction that is dependent on the applied cooling rate. In addition, the possible important implications for the interpretation of spin-crossover behavior in terms of structural changes are discussed.

We have performed a comparative study of rubrene single-crystal field-effect transistors fabricated using different materials as gate insulator. For all materials, highly reproducible device characteristics are obtained. The achieved reproducibility permits to observe that the mobility of the charge carriers systematically decreases with increasing the dielectric constant of the gate insulator, the decrease being proportional to (epsilon)-1. This finding demonstrates that the mobility of carriers in organic single-crystal field-effect transistors is an intrinsic property of the crystal/dielectric interface and that it does not only depend on the specific molecule used., 9 pages, 4 figures

We investigate the effect of a small leakage current through the gate insulator on the stability of organic single-crystal field-effect transistors (FETs). We find that, irrespective of the specific organic molecule and dielectric used, leakage current flowing through the gate insulator results in an irreversible degradation of the single-crystal FET performance. This degradation occurs even when the leakage current is several orders of magnitude smaller than the source-drain current. The experimental data indicate that a stable operation requires the leakage current to be smaller than $10^{-9} \ \mathrm{A/cm}^2$. Our results also suggest that gate leakage currents may determine the lifetime of thin-film transistors used in applications., Comment: submitted to Appl. Phys. Lett

Spin transitions (ST) in transition-metal complexes are a well-known phenomenon in coordination chemistry. Most studied are the systems with a d 6 electron configuration, where the transition goes between essentially diamagnetic and paramagnetic states. In many cases the transition temperature is different when heating or when cooling the sample, and the resulting hysteresis can be applied for storage. So, the colour change would allow possible applications such as in storage devices. Our approach has been the development of systems with Fe(II) and heterocyclic ligands, such as the triazoles and tetrazoles. An overview of recent results is given below, with a focus upon structures and changes in the physical properties. Most structures have the general formula FeL 6 (anion) 2 , with L is a monodentate, or half of a didentate ligand. A special case deals with the compound Fe(btr) 2 (NCS) 2 (H 2 O), the first compound with a trans geometry for the NCS ligands that shows a spin transition. The role of the wa...

Two new isostructural compounds, dichlorobis(1-(2-chloroethyl)tetrazole)copper(II) (1) and dibromobis(1-(2-chloroethyl)tetrazole)copper(II) (2), have been prepared. The synthesis, characterization, and spectral and magnetic properties as well as the crystal and molecular structures of 1 and 2 have been studied. Both complexes form two-dimensional, distorted square grid planes of copper and halides, distinctly separated by layers of tetrazole ligands. The differential (ac) magnetic susceptibility, chi = (deltaM/deltaH)(T), and magnetization M(H) of both complexes have been studied as a function of temperature and field. The compounds possess a ferromagnetic interaction within the isolated copper-halide layers (J/k(B) = 8.0 K, J/k(B) = 10.2 K, respectively, for the chloride and the bromide, and T(c) = 4.75 K, T(c) = 8.01 K). The magnetic coupling J'/k(B) between the different layers is found to be very weak (|J'/J|or= 2 x 10(-2)).

In the title complex, [Cu(BF(4))(2)(1tpc)(4)] [1tpc is 1-(3-chloropropyl)-1,2,4-triazole, C(5)H(8)ClN(3)], the copper(II) centres reside in a tetragonally distorted octahedral coordination environment. Four 1tpc ligands are coordinated to the metal atom via the N4 atom of the triazole rings in a square-planar arrangement, with Cu-N bond lengths in the range 2.002 (2)-2.019 (2) A. Two tetrafluoroborate anions, in the axial positions above and below the square plane, are weakly coordinated to the copper(II) centre, with Cu-F distances of 2.4009 (18) and 2.5096 (18) A.

The synthesis, crystal structure and physical properties of the complex obtained from the reaction between the polyoxometalate anion [PMo12O40]3- copper(II) and the ligand 1-(2-chloroethyl)tetrazole (teec) are described. This compound has been synthesized as a model for designing materials containing both magnetic polyoxometalate anions and iron(II) spin-crossover cations. Keywords. Coordination chemistry; Heterocycles; Polyoxometalates; Structure elucidation; Tetrazole.

This paper reports a case of limited mandibular movement caused by the rare condition of bilateral coronoid hyperplasia. Dental surgeons should be aware of the possibility of this condition when encountering patients with movement problems in the mandible.

The title compound, C50H44, is a derivative of rubrene where tert-butyl side groups are added to two of the pendant aromatic rings. Two polymorphs of this derivative, the title compound (form A) and form B, have been identified. The mol­ecule of form A displays a strongly twisted naphthacene backbone. The in-plane arrangement differs from the classical herringbone structure, resembling a slip–stack structure type with the backbones separated by a minimum 7.0 A in the direction of possible π-stacking.

The title compound, C50H44, is a derivative of rubrene in which tert-butyl side groups are added to two of the pendant aromatic rings. The complete mol­ecule is generated by a mirror plane, and the unsubstituted and substituted pendant aromatic rings are almost perpendicular to the main backbone of the mol­ecule, which is essentially planar.

We report the observation of ambipolar transport in field-effect transistors fabricated on single crystals of Copper- and Iron-Phthalocyanine, using gold as a high work-function metal for the fabrication of source and drain electrodes. In these devices, the room-temperature mobility of holes reaches 0.3 cm$^2$/Vs in both materials. The highest mobility for electrons is observed for Iron-Phthalocyanines and is approximately one order of magnitude lower. Our measurements indicate that these values are limited by extrinsic contact effects due to the transistor fabrication and suggest that considerably higher values for the electron and hole mobility can be achieved in these materials., Submitted to APL

The theoretical model taking into account interactions of a spin-crossover molecule with its two nearest neighbours has been applied to the data on spin crossover equilibria in a series of Fe(II) complexes with halogenated ethyltetrazoles. Transition curves of different shapes, varying from a gradual to a two-step and incomplete spin crossover, have been successfully described by this model. The observed variation of the shape of transition curve originates from ligand-ligand interactions of neighbouring complexes achieved via electrostatic dipole-dipole interactions and hydrogen bonding.

The ligand 1-(2-methoxyethyl)tetrazole (teeOMe) reacts with copper(II) bromide to form two different isomers with the formula [Cu(teeOMe)2Br2]n. The coordination details on the crystal packing are determined by the solvent from which the compound crystallises. In methanol, green crystals of α-[Cu(teeOMe)2Br2] (1) are formed, and these have been characterised by X-ray crystallography (at three temperatures) and magnetic susceptibility measurements. The crystal structure of 1 is built up from square-planar trans-[Cu(teeOMe)2Br2] units. Additional weak axial interactions between the copper centers and the N(2) tetrazole atoms of neighbouring complexes link the [Cu(teeOMe)2Br2] units into two-dimensional layers. Compound 1 displays paramagnetic behaviour (C = 0.41 cm3 K mol−1). In ethanol, yellow–brown crystals of β-[Cu(teeOMe)2Br2] (2) are formed, and these have been characterised by magnetic susceptibility measurements, in addition to IR, ligand field and EPR spectroscopy. The observed magnetic behaviour (C = 0.41 cm3 K mol−1, θ = 30.5 K and J/kB = 16.4 K) is consistent with a structure containing two-dimensional bromide-bridged copper(II) grids. It is proposed that in 2 the square-planar [Cu(teeOMe)2Br2] units are connected via axial Cu–Br interactions, as deduced from comparison of the magnetic properties.

The observation that vasopressin receptors loose their binding capacity on solubilization suggests that lipid-milieu may be a requirement for the binding of vasopressin to these receptors. To preserve the ligand binding capacity, we have developed reconstitution procedures to study solubilized rat liver vasopressin receptors. We report here that vasopressin V1 receptors were efficiently solubilized from rat liver membranes with egg lysolecithin and quantitatively reconstituted into phospholipid vesicles resulting in a 4-fold purification. Binding of [3H]arginine vasopressin to the reconstituted receptors was saturable and of high affinity (Kd = 0.6 +/- 0.1 nM). In competition binding experiments the solubilized, reconstituted receptors exhibited the same pharmacological profile as was observed with vasopressin V1 receptors in membranes.

The rat thoracic aortic smooth muscle cell line, A-10, expresses vasopressin receptors of the V1 subtype. Vasopressin treatment of these cells stimulated the release of arachidonic acid and the formation of diacylglycerol and phosphocholine. These responses to vasopressin were inhibited by the V1-specific antagonist SKF 100273, indicating that these were receptor-mediated phenomena. The mechanisms by which V1 receptors mediate arachidonic acid release appeared to be unaffected by cycloheximide or actinomycin D, suggesting that the release is independent of protein and RNA synthesis. The V1 receptors also appeared to be coupled to a phospholipase C which can hydrolyze phosphatidylcholine, a possible source of the released arachidonic acid. Phosphocholine and diacylglycerol were also generated. The release of arachidonic acid, phosphocholine, or diacylglycerol was not affected by prior treatment of the cells with pertussis toxin (islet-activating protein). Thus, the release of these second messengers is not mediated by the guanine nucleotide-binding protein Gi or other pertussis toxin-sensitive substrates. We conclude that V1 receptors induce the release of arachidonic acid and the formation of diacylglycerol and phosphocholine via the activation of both a phosphatidylinositol- and phosphatidylcholine-specific phospholipase C.