Anion Effect on Structure of Silver(I) Complexes with New Unsymmetrical Tripodal Ligand

Reactions of new unsymmetrical pyridyl‐ and imidazoyl‐containing tripodal ligand, 3‐(1H‐imidazol‐1‐yl)‐N,N‐bis(2‐pyridylmethyl)propan‐1‐amine ( L ), with varied silver(I) salts result in formation of three supramolecular architectures [Ag₂L₂](BF₄)₂·H₂O ( 1 ), [Ag₂L₂](ClO₄)₂·H₂O ( 2 ) and [Ag₃L₂](CF₃SO₃)₃ ( 3 ). All the structures were established by single‐crystal X‐ray diffraction analysis. In the solid state, three complexes consist of one‐dimensional infinite chains, in which the conformation and the bridging mode of L for complexes 1 and 2 are the same but 3 different. There are Ag···Ag and π‐π interactions in 3 . The results imply that the shape and size of the anion have great impact on the structure of the complexes. The complexes were also characterized by electrospray mass spectrometry.     

Structure and Properties of [Fe(4)S(4){2,6-bis(acylamino)benzenethiolato-S}(4)](2)(-) and [Fe(2)S(2){2,6-bis(acylamino)benzenethiolato-S}(4)](2)(-): Protection of the Fe-S Bond by Double NH.S Hydrogen Bonds

Iron-sulfur clusters containing a singly or doubly NH.S hydrogen-bonded arenethiolate ligand, [Fe(4)S(4)(S-2-RCONHC(6)H(4))(4)](2)(-) (R = CH(3), t-Bu, CF(3)), [Fe(4)S(4){S-2,6-(RCONH)(2)C(6)H(3)}(4)](2)(-), [Fe(2)S(2)(S-2-RCONHC(6)H(4))(4)](2)(-) (R = CH(3), t-Bu, CF(3)), and [Fe(2)S(2){S-2,6-(RCONH)(2)C(6)H(3)}(4)](2)(-), were synthesized as models of bacterial [4Fe-4S] and plant-type [2Fe-2S] ferredoxins. The X-ray structures and IR spectra of (PPh(4))(2)[Fe(4)S(4){S-2,6-(CH(3)CONH)(2)C(6)H(3)}(4)].2CH(3)CN and (NEt(4))(2)[Fe(2)S(2){S-2,6-(t-BuCONH)(2)C(6)H(3)}(4)] indicate that the two amide NH groups at the o,o'-positions are directed to the thiolate sulfur atom and form double NH.S hydrogen bonds. The NH.S hydrogen bond contributes to the positive shift of the redox potential of not only (Fe(4)S(4))(+)/(Fe(4)S(4))(2+) but also (Fe(4)S(4))(2+)/(Fe(4)S(4))(3+) in the [4Fe-4S] clusters as well as (Fe(2)S(2))(2+)/(Fe(2)S(2))(3+) in the [2Fe-2S] clusters. The doubly NH.S hydrogen-bonded thiolate ligand effectively prevents the ligand exchange reaction by benzenethiol because the two amide NH groups stabilize the thiolate by protection from dissociation.     

Two- and Three-dimensional Frameworks with (6,3) and (10,3)-a Topology from Self-assembly of Three-connecting Organic Ligands with Cadmium(II) and Silver(I) Salts

Assembly of three-connecting ligands 1,3,5-tris(1-imidazolyl)benzene (tib) and 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) with cadmium(II) and silver(I) salts provide new metal-organic frameworks, [Cd(tib)₂](NO₃)₂·4H₂O (1), [Ag(tib)(PPh₃)](CF₃SO₃) (2) and [Ag(titmb)(PPh₃)](CF₃SO₃)·1.5H₂O (3) (PPh₃=triphenylphosphine). Single-crystal X-ray diffraction studies reveal that complexes 1 and 3 are two-dimensional honeycomb networks, while complex 2 is a noninterpenetrated three-dimensional architecture with (10,3)-a topology. The results indicate that the nature (structure and flexibility) of the organic ligands and the bulky auxiliary ligand have great impact on the assembly and structure of metal-organic frameworks. The photoluminescent properties of the synthesized complexes were studied in the solid state at room temperature.     

Ethylaluminum oxide catalysts from Et2AlOLi–Et2AlCl binary system in relation to species of AlEt3–water catalyst

Equimolar reaction of Et₂AlOLi and Et₂AlCl gave Et₂AlOAlEt₂. The catalyst behavior for polymerization of acetaldehyde, propylene oxide, and epichlorohydrin was compared with that of the AlEt₃–H₂O (1:0.5) catalyst system. The thermal disproportionation product of Et₂AlOAlEt₂ derived from Et₂AlOLi–Et₂AlCl had the structure, ? (EtAlO)_n? , and it showed catalyst behavior quite similar to that of the product obtained by the same treatment of AlEt₃–H₂O (1:0.5). These ethylaluminum oxides can be regarded as species predominating in AlEt₃–H₂O (1:0.5) and AlEt₃–H₂O (1:1), respectively. Stereospecific or high molecular weight polymerizations of these species were investigated.     

Secondary ion emission processes of sputtered alkali ions from alkali/Si(100) and Si(111)

The secondary alkali ion yield vs. the work function change (Δφ) of Na, K and Cs/Si(100) and Si(111) was measured to discuss the details of secondary ion emission processes. In the case of alkali/metal systems, the secondary ion emission is explained by the electron tunneling model. In this model, the ionization of the ejected atom occurs as a result of electron resonant tunneling through the potential barrier separating an atom and a metal, and the secondary ion yield depends on exponentially the work function change of metal surface. For alkali/Si(100) systems, the secondary ion emission processes are explained in terms of the electron tunneling model since the secondary alkali ion yield vs. the work function change (Δφ) follows the exponential manner. However, it is not easy to apply the simple electron tunneling model to our experimental results for alkali/Si(111) systems. There is the essential difference in surface structures between Si(100) and Si(111). Therefore, it is suggested that the local electronic environment around the adsorbates might be taken into consideration for alkali/Si(111) systems.     

The classification of 3-dimensional noetherian cubic Calabi–Yau algebras

It is known that every 3-dimensional noetherian Calabi–Yau algebra generated in degree 1 is isomorphic to a Jacobian algebra of a superpotential. Recently, S.P. Smith and the first author classified all superpotentials whose Jacobian algebras are 3-dimensional noetherian quadratic Calabi–Yau algebras. The main result of this paper is to classify all superpotentials whose Jacobian algebras are 3-dimensional noetherian cubic Calabi–Yau algebras. As an application, we show that if S is a 3-dimensional noetherian cubic Calabi–Yau algebra and σ is a graded algebra automorphism of S, then the homological determinant of σ can be calculated by the formula $\mathrm{hdet}\sigma ={(\det \sigma )}^2$ with one exception.     

Metal-organic architectures of silver(I), cadmium(II), and copper(II) with a flexible tricarboxylate ligand

Three novel metal-organic architectures, [Ag3(bta)].1.5H2O (1), [Cd3(bta)2(H2O)7].5H2O (2), and [Cu11(bta)6(Hbta)2(H2O)10].29H2O (3), were obtained by reactions of the corresponding metal salts with a flexible tripodal ligand, benzene-1,3,5-triacetic acid (H3bta), and their structures were determined by single-crystal X-ray diffraction studies. The results revealed that, in complexes 1 and 2, the carboxylate groups of the bta3- ligand adopted varied coordination modes to link metal atoms and further to form three-dimensional structures with open channels occupied by water molecules, while in complex 3, for the first time, the flexible H3bta acted as a secondary building unit to generate a novel nanometer-sized metallocage, which is composed of a Cu(II) paddle wheel (square secondary building units) and bta3-/Hbta2- organic links (triangular secondary building units). The photoluminescence properties of complexes 1 and 2 were investigated, and the results showed that 2 exhibited photoluminescence in the solid state at room temperature.     

Shadow Doppler velocimetry with double fiber-array sensors

Shadow Doppler velocimetry (SDV) systems with double fiber-array sensors were developed for the measurements of particle trajectory angles and for the stereoscopic investigation of particles. The parallel two-line fiber-array configuration improves the accuracy of the trajectory angle measurement in a plane perpendicular to the optical axis, which contributes to the high accuracy of the particle shape reconstruction process. It also provides information on the other trajectory angle in a plane parallel to the two laser beams. Furthermore, it realizes "time-of-flight" velocity measurement, which provides the possibility to simplify the original SDV setup by removing the laser Doppler velocimetry (LDV) components. On the other hand, stereoscopic SDV was also developed, which is effective in cases where three-dimensional characteristics of shape, orientation, or behavior of particles are important.     

Fluctuating hydrodynamic equations of mixed and of chemically reacting gases

The method of the nonlinear Langevin equation is generalized to ordinary mixed and to chemically reacting gases. The stochastic Boltzmann equations of these gases, the fluctuating hydrodynamic equations of mixed gases, and the Langevin equations for the number density of each component of a reaction-diffusion system are obtained.This work was supported financially by the Alexander von Humboldt Foundation. The main part of the paper was written during the author's stay at the Max-Planck Institut für Festkörperforschung (Stuttgart) as a Humboldt fellow.