Vapor-Induced Conversion of a Centrosymmetric Organic–Inorganic Hybrid Crystal into a Proton-Conducting Second-Harmonic-Generation-Active Material

Chemical responsivity in materials is essential to build systems with switchable functionalities. However, polarity-switchable materials are still rare because inducing a symmetry breaking of the crystal structure by adsorbing chemical species is difficult. In this study, we demonstrate that a molecular organic–inorganic hybrid crystal of (NEt4)2[MnN(CN)4] (1) undergoes polarity switching induced by water vapor and transforms into a rare example of proton-conducting second-harmonic-generation-active material. Centrosymmetric 1 transforms into noncentrosymmetric polar 1·3H2O and 1·MeOH by accommodating water and methanol molecules, respectively. However, only water vapor causes a spontaneous single-crystal-to-single-crystal transition. Moreover, 1·3H2O shows proton conduction with 2.3 × 10–6 S/cm at 298 K and a relative humidity of 80%

Employment Discrimination: Recent Developments in the Supreme Court (Symposium: The Supreme Court and Local Government Law: The 1992-93 Term)

At a symposium entitled, “The Supreme Court and Local Government Law; The 1992/93 Term”, Professor Eileen Kaufman spoke about the cases involving employment discrimination that were decided during that particular Term, Hazen Paper Company v. Biggins and St. Mary\u27s Honor Center v. Hicks. While Hazen is an age discrimination case and St. Mary\u27s is a Title VII case, they can be viewed as companion cases which serve to explain what an employment discrimination plaintiff must now establish when attempting to prove disparate treatment by indirect evidence. By way of preview, suffice it to say that plaintiff\u27s task has been made more difficult as a result of these decisions

Metal Dilution Effects on the Reverse Spin Transition in Mixed Crystals of Type [Co_1–<i>x</i>Zn_<i>x</i>(C₁₆-terpy)₂](BF₄)₂ (<i>x</i> = 0.1–0.7)

Metal dilution effects on reverse spin transition (rST) in mixed crystals of type [Co_1–<i>x</i>Zn_<i>x</i>­(C₁₆-terpy)₂]­(BF₄)₂ (<i>x</i> = 0.1–0.7) were investigated by comparison with behavior of [Co_1–<i>x</i>Fe_<i>x</i>­(C₁₆-terpy)₂]­(BF₄)₂ (<i>x</i> = 0.1–0.4). In the mixed crystals, the Zn complexes increased rST temperatures linearly with increasing values of <i>x</i>, without changing the hysteresis width, while the Fe complexes decreased rST temperatures. Moreover, the strength of the metal dilution effects in the CoZn mixed crystals is weaker than what occurs in the CoFe mixed crystals

Metal Dilution Effects on the Reverse Spin Transition in Mixed Crystals of Type [Co_1–<i>x</i>Zn_<i>x</i>(C₁₆-terpy)₂](BF₄)₂ (<i>x</i> = 0.1–0.7)

Metal dilution effects on reverse spin transition (rST) in mixed crystals of type [Co_1–<i>x</i>Zn_<i>x</i>­(C₁₆-terpy)₂]­(BF₄)₂ (<i>x</i> = 0.1–0.7) were investigated by comparison with behavior of [Co_1–<i>x</i>Fe_<i>x</i>­(C₁₆-terpy)₂]­(BF₄)₂ (<i>x</i> = 0.1–0.4). In the mixed crystals, the Zn complexes increased rST temperatures linearly with increasing values of <i>x</i>, without changing the hysteresis width, while the Fe complexes decreased rST temperatures. Moreover, the strength of the metal dilution effects in the CoZn mixed crystals is weaker than what occurs in the CoFe mixed crystals

Intermolecular Interaction Tuning of Spin-Crossover Iron(III) Complexes with Aromatic Counteranions

Iron­(III) spin-crossover (SCO) complexes [Fe­(qsal)₂]­BS·MeOH·H₂O (<b>1</b>), [Fe­(qsal)₂]­(NS)·MeOH (<b>2</b>), [Fe­(qnal)₂]­(NS) (<b>3</b>), and [Fe­(qnal)₂]­PS·MeOH·CH₂Cl₂ (<b>4</b>) (Hqsal, <i>N</i>-(8-quinolinyl)­salicylaldimine; Hqnal, <i>N</i>-(8-quinolinyl)-2-hydroxy-1-naphthaldimine; BS, benzenesulfonate; NS, 1-naphthalenesulfonate; PS, 1-pyrenesulfonate) have been synthesized and characterized by X-ray structure determinations and temperature-dependent magnetic susceptibility measurements. The aromatic counteranions BS, NS, and PS can be used for the tuning of intermolecular coupling through a variety of weak interactions. All of the complexes show temperature-dependent SCO behavior. but the light-induced excited spin-state trapping (LIESST) effect was observed only for <b>1</b>, <b>3</b>, and <b>4</b> when the samples were illuminated (λ 808 nm) for 1 h at 5 K. In particular, 59% of the LS form of <b>1</b> was converted to the metastable HS state by illumination, equal to the highest degree of conversion yet known for LIESST in [Fe­(qsal)₂]⁺ derivatives. The lack of a LIESST effect for <b>2</b> may be due to the relatively limited degree of interaction between the cations and anions in the lattice, reflected in a much longer minimum Fe···Fe separation in this complex in comparison to the others

Super Dielectric Materials of Two-Dimensional TiO₂ or Ca₂Nb₃O₁₀ Nanosheet Hybrids with Reduced Graphene Oxide

High dielectric constants (ε_r) were observed in two-dimensional composites obtained from stacking of reduced graphene oxide (RGO) with Ca₂Nb₃O₁₀ and with TiO₂ nanosheets. The relative dielectric permittivity values of the composites were found to be higher than 10⁵, an amazingly high value compared to that of similar GO composites and other common dielectric materials. As a consequence, we considered application of the hybrids as super dielectric materials in high capacitance supercapacitors. The route to high capacitance involves the variation of oxygen vacancies within the surface and in the closest bulk interior of the hybrids. The effective charges generated throughout the metal oxide and carbon–oxygen polar bonding systems within the graphene skeleton appear to highly influence dielectric polarization. Moreover, the replenishment of oxygen vacancies at the RGO and metal oxide interface also contributes to polarizability