A lariat‐functionalized copper(II) di­imine–dioxime complex

The dimeric title copper(II) complex, diaqua‐1κO,2κO‐bis[3,9‐dimethyl‐6‐(2‐pyridyl­methyl)‐4,8‐di­aza­undeca‐3,8‐di­ene‐2,10‐dione dioximato(1?)]‐1k⁴N²,N⁴,N⁸,N¹⁰;1:2κ⁵O²:N²,N⁴,N⁸,N¹⁰‐dicopper(II) diperchlorate, [Cu₂(C₁₇H₂₄N₅O₂)₂](ClO₄)₂, crys­tallizes with one Cu atom in a square‐pyramidal environment and the other Cu atom displaying a distorted octahedral coordination. In each case, the four N atoms in the core of the ligand (two imine and two oxime N atoms) form the base of the pyramid, with a water mol­ecule at an apex. The two parts of the dimer are linked by an interaction [2.869 (2) Å] between one of the Cu atoms and one of the oxime O atoms coordinated to the second Cu atom, and also by a hydrogen bond between the apical water mol­ecule on the second Cu atom and the pyridyl N atom from the coordination sphere of the first Cu atom. The pyridyl N atoms of the lariat arms are not coordinated to either of the Cu atoms. Thus, this potentially pentadentate ligand is only tetradentate when coordinated to Cu^II.     

Stokeslets-meshfree computations and theory for flow in a collapsible microchannel

We present both a theoretical model and Stokeslets-meshfree computations to study the induced flow motions and transport in a 2D microchannel with moving multiple prescribed dynamic collapses (contractions) along the upper wall. The channel is assumed to have a length that is much greater than its width, i.e., ${(\delta = W/L \ll1)}$ . The wall contractions are set to move with or without time (phase) lags with respect to each other. The theoretical analysis presented is based on the quasi-steady state approximations and the lubrication theory at the low Reynolds number flow regime. The meshfree numerical method is based on the method of fundamental solutions MFS, which uses a set of singularized force elements called Stokeslets to induce the flow motions. The flow field developments and structures induced by these wall contractions are given at various time snapshots during the collapsing cycle. The effect of the wall contractions amplitudes and the phase lags between individual contractions on the flow variables and on the time-averaged net flow over a complete cycle of contractions motions is studied. The present study is motivated by pumping mechanisms observed in insects, physiological systems that use multiple contractions to transport fluid, and the emerging novel microfluidic devices that mimic these systems.     

Structural Report for Sc[(R,R)-norephedrine-pybox](OTf)3 Dimeric Complex

Abstract The title compound containing two metal centers each complexes to one enantiopure chiral norephedrine-derived pyridyl-(bis) oxazoline (pybox) ligand and linked by two hydroxide bridges, crystallizes to give rodlike form in the space group P2₁(# 4). Cell Parameters are a = 10.2344(18) ?, b = 13.952(3) ?, c = 23.371(4) ?, β = 94.586(4)°, V = 3326.6(10) ?³. The metal-hydroxide motif forms a square plane at the center of the structure with the scandium centers exhibiting a distorted pentagonal bipyramid coordination sphere consisting of the chelating ligand and two additional triflouromethyl sulfonyloxy species positioned anti to each other. Graphical abstract The complex contains two metal centers each complexes to one enantiopure chiral norephedrine-derived pyridyl-(bis) oxazoline (pybox) ligand and linked by two hydroxide bridges. Structural report for Sc[(R,R)-norephedrine-pybox](OTf)₃ dimeric complex Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Shape-shifting tetranuclear oxo-bridged manganese cluster: relevance to photosystem II water oxidase active site

The redox properties of the "dimer-of-dimers" complex, [{Mn2(mu-O)2(tphpn)}2]4+ (1) (where Htphpn = N,N,N',N'-tetra(2-methylpyridyl)-2-hydroxypropane-diamine) were investigated. The structure changes dramatically to an adamantane-shaped core upon one-electron oxidation. On the other hand, the one-electron reduced product of 1, [Mn4O4(tphpn)2]3+, exhibits a hyperfine-structured multiline EPR signal very similar to the so-called S0 state of the tetramanganese cluster, which resides at the Photosystem II water oxidase active site.     

Doubling measures and quasiconformal maps

Part of the research for this paper was done while the author was visiting the Mittag-Leffler Institute. She wishes to thank the Institute for its hospitality. The author was also supported by Grant #DMS 9004251 from the U.S. National Science Foundation.     

On <Emphasis Type="Italic">g</Emphasis>-functions for Laguerre function expansions of Hermite type

We examine weighted L ^p boundedness of g-functions based on semigroups related to multi-dimensional Laguerre function expansions of Hermite type. A technique of vector-valued Calderón–Zygmund operators is used.     

Luminescent chains formed from neutral, triangular gold complexes sandwiching TlI and AgI. Structures of (Ag([Au(mu-C2,N3-bzim)]3)2)BF4.CH2Cl2, (Tl([Au(mu-C2,N3-bzim)]3)2)PF(6).0.5THF (bzim = 1-benzylimidazolate), and (Tl([Au(mu-C(OEt)=NC6H4CH3)]3)2)PF6.THF, with MAu6 (M = Ag+, Tl+) cluster cores

It has been found that several trinuclear complexes of AuI interact with silver and thallium salts to intercalate Ag+ and Tl+ cations, thereby forming chains. The resulting sandwich clusters center the cations between the planar trinuclear moieties producing structures in which six AuI atoms interact with each cation in a distorted trigonal prismatic coordination. The resultant (B3AB3B3AB3)infinity pattern of metal atoms also shows short (approximately 3.0 A) aurophilic interactions between BAB molecular centers. These compounds display a strong visible luminescence, under UV excitation, which is sensitive to temperature and the metal ion interacting with the gold. X-ray crystal structures are reported for Ag([Au(mu-C2,N3-bzim)]3)2BF4CH2Cl2 (P1, Z = 2, a = 14.4505(1) A; b = 15.098(2)A; c = 15.957(1)A; alpha = 106.189(3) degrees; beta = 103.551(5) degrees; gamma = 101.310(5) degrees); Tl([Au(mu-C2,N3-bzim)]3)2PF(6)05C4H8O (P1, Z = 2, a = 15.2093(1)A; b = 15.3931(4)A; c = 16.1599(4)A; alpha = 106.018(1) degrees; beta = 101.585(2) degrees; gamma = 102.068(2) degrees); and Tl([Au(mu-C(OEt)=NC6H4CH3)]3)2PF6.C4H8O (P2(1)/n, Z = 4, a = 16.4136(3)A; b = 27.6277(4)A; c = 16.7182(1)A; beta = 105.644(1) degrees). Each compound shows that the intercalated cation, Ag+ or Tl+, coordinates to a distorted trigonal prism of six AuI atoms. The counteranions reside well apart from the cations between the cluster chains.