Thiacalix[4]arene-Based Three-Dimensional Coordination Polymers Incorporating Neutral Bridging Coligands

Employing a solvothermal procedure and use of p-tert-butyl-thiacalix[4]arene tetraacetic acid (H4TCTA) and the nitrate salts of cobalt(II) and cadmium(II) have enabled isolation of four three-dimensional metal–organic frameworks (1–4) in the presence of three different types of neutral bridging coligands. In one case, 3, a mixed metal ion system (Co2+/Na+) was obtained. First, the reaction of H4TCTA with Co(NO3)2·6H2O together with the linear bridging coligand BPY (4,4′-bipyridine) afforded a mixture of two 3D frameworks of types [Co2(TCTA)(BPY)]n (1) and [Co2(TCTA)(BPY)2(H2O)4]n (2). Compound 1 features a paddle-wheel unit incorporating Co2+ pairs, Co2(carboxylate)4, involving four different TCTA units in two dimensions and BPY pillaring in the third. In 2, 2D sheets consisting of BPY–Co repeating chains stacked in an A-B-A-B pattern are pillared by TCTA to yield the 3D motif. In the second reaction system, the use of H4TCTA with Co(NO3)2·6H2O in the presence of the bent bridging coligand BPPA (N,N′-bis(pyridine-4-yl)-isophthalamine) and NaOH afforded {[Co3Na2(TCTA)2(BPPA)2(H2O)2]·4DMF·4H2O}n (3). In 3, TCTA yields a honeycomb-shaped 2D sheet via Co–O(carboxylate) bonds; these sheets are linked by Co–O(carboxylate) and Co–(BPPA)–Co bridging bonds to afford the 3D motif. In this case, the Na atom locates inside the calix cavity in a distorted square planar coordination environment and is stabilized by η3-type cation···π interactions. In the third system, the use of H4TCTA with Cd(NO3)2·6H2O in the presence of the flexible bridging coligand diaminohexane (DAH) gave {[Cd2(TCTA)(DAH)(DMF)2]·2DMF·2H2O}n (4), which features an unusual PtS-like 3D structure. The results confirm that the nature of the extended 3D structures is influenced by the bridging coordination behavior of the coligands. In all these structures, the TCTA ligands adopt a 1,3-alternate conformation. Thermal gravimetric analysis performed on the present MOFs revealed that three of these compounds have high thermal stability (∼300 °C)

Homonuclear and Heteronuclear Complexes of Calix[4]-<i>bis</i>-monothiacrown‑5 with Oligomer and Polymer Structures

Homo- and heteronuclear complexes (<b>1</b>–<b>7</b>) of calix[4]-<i>bis</i>-monothiacrown-5 (<b>L</b>) with mercury­(II), cadmium­(II), copper­(I), and potassium­(I) salts adopting dimer, tetramer, one-dimensional (1D), and two-dimensional (2D) polymer structures with different coordination modes and connectivity patterns were prepared and structurally characterized. Reactions of <b>L</b> with mercury­(II) iodide and mercury­(II) thiocyanate afforded a dimer complex [Hg₄(<b>L</b>)₂I₈]·CH₂Cl₂ (<b>1</b>) and a 1D coordination polymer {[Hg₂(<b>L</b>)­(SCN)₄]·CH₂Cl₂}_<i>n</i> (<b>2</b>), respectively, in which the exocyclic dimercury­(II) complex units of <b>L</b> are doubly linked by the anions. Reactions of <b>L</b> with cadmium­(II) iodide in the absence and the presence of mercury­(II) iodide gave isostructural 1D coordination polymers [Cd₂(<b>L</b>)­I₄]_<i>n</i> (<b>3</b>) and {[Cd₂(<b>L</b>)­I₄]­[CdHg­(<b>L</b>)­I₄]}_<i>n</i> (<b>4</b>), respectively. In the isostructure of <b>3</b> and <b>4</b>, the ligands are alternately linked by the exocyclic M-I₂-M squares via monocadmium­(II)-mediated and dicadmium­(II)-mediated modes, respectively. Reaction of <b>L</b> with copper­(II) thiocyanate in the presence of potassium­(I) thiocyanate afforded a discrete complex {[(K₂<b>L</b>)₄Cu₆(SCN)₁₀]­[K₂<b>L</b>]₂[Cu­(SCN)₃]₃·2CH₂Cl₂·CH₃CN} (<b>5</b>) consisting of three separated parts: dipotassium­(I) tetramer part linked with a oligomer copper­(I) thiocyanate backbone, dipotassium­(I) monomer part, and trithiocyanato copper­(I) complex part. When a mixture of mercury­(II) thiocyanate and potassium­(I) thiocyanate was used, a grid-type 2D heteronuclear polymer complex [Hg₃(K₂<b>L</b>)­(SCN)₈]_<i>n</i> (<b>6</b>) in which the 1D mercury­(II) thiocyanato backbones cross-linked by endocyclic dipotassium­(I) complex units of <b>L</b> was isolated. One pot reaction of <b>L</b> with a mixture of iodide salts of potassium­(I), mercury­(II), and cadmium­(II) gave a binary mixed product of a discrete complex [(K₂<b>L</b>)₂(Cd₃I₈)]­[Cd₄I₁₀] (<b>7</b>) and a heteronuclear 2D network (<b>8</b>) which can be manually separated because of the colorless platy and orange–yellow block shapes of the crystals, respectively. In <b>7</b>, the endocyclic dipotassium­(I) complex of <b>L</b> is linked by Cd₃I₈ clusters

Selective Allowance of Precipitation from Oversaturated Solution Using Surface Structures

Precipitation is a well-known phenomenon commonly observed in salt ponds. However, it causes pipe clogging in industrial sites, which can be resolved by controlling the direction of precipitation. Herein, we propose a method to control the precipitation direction by changing the structures and properties of the solid surface. Bare, nanostructured, microstructured, and micro/nanostructured surfaces were immersed in the same saturated aqueous NaCl solution, and the heights at which precipitation occurred in the different specimens were compared. On bare and nanostructured surfaces, NaCl deposits as a flat layer on the surface, while on micro and micro/nanostructured surfaces, it forms a thick deposit in a direction perpendicular to the surface. When the same experiment was conducted on surfaces made by patterning different structural surfaces, the precipitates did not spread on the surface with microscale structures. We believe that this novel approach may prove useful in solving the problems caused by precipitation

An Unusual Interweaving in a 3-Fold Interpenetrated Pillared-Layer Zn(II) Coordination Polymer with a Long Spacer Ligand

This communication describes a unique interweaving of a pyridyl-based long linear spacer ligand, 1,4-bis­[2-(4-pyridyl)­ethenyl]­benzene (bpeb), in the triply interpenetrated pillar-layer porous coordination polymer [Zn₂(ndc)₂(bpeb)]·DMF·3H₂O (where ndc = 2,6-naphthalenedicarboxylate) containing a paddle-wheel secondary building unit (SBU) with α-Po topology. When the dicarboxylate is changed diethylpyrocarbonate (DEPC) from ndc to biphenyl-4,4′-dicarboxylate (bpdc), the reaction furnished a completely different 3-fold interpenetrating three-dimensional coordination polymer [Zn₃(bpdc)₃(bpeb)]·0.5DMSO·1.5H₂O having a uninodal eight connected network structure with hexagonal bipyramidal SBUs

An Unusual Interweaving in a 3-Fold Interpenetrated Pillared-Layer Zn(II) Coordination Polymer with a Long Spacer Ligand

This communication describes a unique interweaving of a pyridyl-based long linear spacer ligand, 1,4-bis­[2-(4-pyridyl)­ethenyl]­benzene (bpeb), in the triply interpenetrated pillar-layer porous coordination polymer [Zn2(ndc)2(bpeb)]·DMF·3H2O (where ndc = 2,6-naphthalenedicarboxylate) containing a paddle-wheel secondary building unit (SBU) with α-Po topology. When the dicarboxylate is changed diethylpyrocarbonate (DEPC) from ndc to biphenyl-4,4′-dicarboxylate (bpdc), the reaction furnished a completely different 3-fold interpenetrating three-dimensional coordination polymer [Zn3(bpdc)3(bpeb)]·0.5DMSO·1.5H2O having a uninodal eight connected network structure with hexagonal bipyramidal SBUs

Quantum computation and simulation with vibrational modes of trapped ions

Vibrational degrees of freedom in trapped-ion systems have recently been gaining attention as a quantum resource, beyond the role as a mediator for entangling quantum operations on internal degrees of freedom, because of the large available Hilbert space. The vibrational modes can be represented as quantum harmonic oscillators and thus offer a Hilbert space with infinite dimension. Here we review recent theoretical and experimental progress in the coherent manipulation of the vibrational modes, including bosonic encoding schemes in quantum information, reliable and efficient measurement techniques, and quantum operations that allow various quantum simulations and quantum computation algorithms. We describe experiments using the vibrational modes, including the preparation of non-classical states, molecular vibronic sampling, and applications in quantum thermodynamics. We finally discuss the potential prospects and challenges of trapped-ion vibrational-mode quantum information processing

Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications

Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe₂ solar cell with TCE of our AgNW­(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE

Quantum simulation of molecular spectroscopy in trapped-ion device

Molecules are the most demanding quantum systems to be simulated by quantum computers because of their complexity and the emergent role of quantum nature. The recent theoretical proposal of Huh et al. (Nature Photon., 9, 615 (2015)) showed that a multi-photon network with a Gaussian input state can simulate a molecular spectroscopic process. Here, we report the first experimental demonstration of molecular vibrational spectroscopy of SO$_{2}$ with a trapped-ion system. In our realization, the molecular scattering operation is decomposed to a series of elementary quantum optical operations, which are implemented through Raman laser beams, resulting in a multimode Gaussian (Bogoliubov) transformation. The molecular spectroscopic signal is reconstructed from the collective projection measurements on phonon modes of the trapped-ion system. Our experimental demonstration would pave the way to large-scale molecular quantum simulations, which are classically intractable

Tailored Band Structure of Cu(In,Ga)Se₂ Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function

An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu­(In,Ga)­Se2 (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations. To mitigate this shortcoming, we prepared gently etched devices and analyzed their properties using micro-Raman scattering spectroscopy, Kelvin probe force microscopy, and photoluminescence measurements. The atomic distributions and microstructures of the devices were investigated, and the defect densities in the device bulk were determined via admittance spectroscopy. The effects of Ga grading on the charge transport at the CIGS–CdS interface were categorized into various types of band offsets, which were directly confirmed by our experiments. The results indicated that reducing open-circuit voltage loss is crucial for obtaining a higher power conversion efficiency. Although the large Ga grading in the CIGS absorber induced higher defect levels, it effectuated a smaller open-circuit voltage loss because of carrier transport enhancement at the absorber–buffer interface, resulting from the optimized conduction band offsets

Quantum simulation of the quantum Rabi model in a trapped ion

The quantum Rabi model, involving a two-level system and a bosonic field mode, is arguably the simplest and most fundamental model describing quantum light-matter interactions. Historically, due to the restricted parameter regimes of natural light-matter processes, the richness of this model has been elusive in the lab. Here, we experimentally realize a quantum simulation of the quantum Rabi model in a single trapped ion, where the coupling strength between the simulated light mode and atom can be tuned at will. The versatility of the demonstrated quantum simulator enables us to experimentally explore the quantum Rabi model in detail, including a wide range of otherwise unaccessible phenomena, as those happening in the ultrastrong and deep strong coupling regimes. In this sense, we are able to adiabatically generate the ground state of the quantum Rabi model in the deep strong coupling regime, where we are able to detect the nontrivial entanglement between the bosonic field mode and the two-level system. Moreover, we observe the breakdown of the rotating-wave approximation when the coupling strength is increased, and the generation of phonon wave packets that bounce back and forth when the coupling reaches the deep strong coupling regime. Finally, we also measure the energy spectrum of the quantum Rabi model in the ultrastrong coupling regime