Colorimetric determination of Cu2+ in simulated wastewater using naphthalimide-based Schiff base

A new Cu²⁺-selective colorimetric sensor was developed by combining the chromophore 3-hydroxynaphthalimide with diaminomaleonitrile. The sensor showed Cu²⁺-selective colorimetric signaling behavior in dimethylsulfoxide, indicated by a solution color change from yellow to pink, which was readily discernible without any external devices. Practical application of the sensor to the detection of Cu²⁺ in an aqueous solution containing other environmentally relevant metal ions by selective two-phase liquid-liquid extraction with ethyl acetate was possible. Particularly, extractive signaling of Cu²⁺ in simulated semiconductor wastewater with a readily-usable smartphone as a colorimetric data capture and analysis tool was successfully conducted.     

A novel two-dimensional zinc(II) complex of a di-N-carboxymethylated tetraaza macrocycle linked by hydrogen-bonds

The complex [ZnL]·10H₂O (L = 2,13-bis(2-carboxymethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) has been synthesized and structurally characterized. It crystallizes in the monoclinic system, space group P2₁/c with a = 10.159(1), b = 10.066(3), c = 17.268(2) Å, = 102.92(1)°, V = 1721.0(5) ų, and Z = 2. The crystal structure reveals an axially elongated octahedral geometry with bonds from the zinc(II) ion to the secondary and tertiary amines of the macrocycle and two oxygen atoms of the pendant carboxymethyl groups. The molecules of the zinc(II) complex are connected into a two-dimensional chain via hydrogen bonds.     

Low temperature GaAs grown by gas source molecular beam epitaxy

Low temperature growth of GaAs by gas source molecular beam epitaxy (GSMBE) is investigated. Reflection high energy electron diffraction is used to monitor the low temperature buffer (LTB) growth and anneal conditions. Growth at low temperatures with dimeric arsenic is more sensitive to the V/III flux ratios and substrate temperatures than with As₄ used in solid source MBE. Temperature dependent conductivity and deep level transient spectroscopy measurements are presented to observe trap outdiffusion from the LTB into subsequently grown FET channels. Low temperature photoluminescence spectra show degradation of quantum well properties when LTBs are grown with increasing V/III flux ratios.     

Preparation of mesoporous carbon/manganese oxide materials and its application to supercapacitor electrodes

By employing a new template method using surfactant/silicate solution template, highly mesoporous carbon/manganese oxide composite materials were prepared in one step and their performance as electrodes of supercapacitor was investigated. Because of the high dispersion of Mn oxide and well developed mesoporosity of carbon, a high specific capacitance and an improved rate performance were observed at the electrodes fabricated by Mn/carbon composite materials.     

Synthesis and Crystal Structure of Phenolato-Bridged Dinuclear Copper(II) Complex with (2-Hydroxybenzyl)(2-pyridylmethyl)amine

Abstract  

The tridentate Schiff base phenol-containing ligand (2-hydroxybenzyl)(2-pyridylmethyl)amine (Hbpa) reacts with copper(II) perchlorate to give the phenolato-bridged dinuclear complex [Cu(bpa)(H₂O)]₂·2ClO₄ (1). Each copper(II) ion exhibits a distorted square-pyramidal environment, being coordinated by two nitrogen atoms and two phenolato oxygen atoms of the two deprotonated bpa ligands, and one oxygen atom of the water molecule. It crystallizes in the triclinic system P-1 with a = 7.8790(6), b = 8.9345(7), c = 12.0207(9) ?, α = 69.158(1), β = 85.307(1), γ = 76.629(1)°, V = 769.39(10) ?³, Z = 1. Cyclic voltammetry of 1 gives two oxidation and two reduced processes.     

Crystal Structure of [2,13-Dibenzyl-5,16-dimethyl-2,6,13,17-tetraazatricyclo(14,4,0<Superscript>1.18</Superscript>,0<Superscript>7.12</Superscript>)docosane]copper(II) Diperchlorate

Abstract  

In the title compound, [Cu(C₃₄H₅₂N₄)](ClO₄)₂, the Cu(II) ion has a square-planar coordination somewhat distorted towards tetrahedral geometry. The macrocyclic ligand adopts a less stable trans-I (RSRS) configuration. The two benzyl groups and two secondary amine H atoms are oriented towards the same side of the macrocyclic plane. The two six-membered rings are in slightly distorted chair and unsymmetrical twist-boat forms while both five-membered chelate rings are in the gauche conformation. The longer distances (2.050(4) and 2.035(4) Å) of Cu–N(tertiary) compared to 2.017(4) and 1.990(4) Å for Cu–N(secondary) may be due to the steric effects of the attached two benzyl groups on the tertiary N atoms. The crystal structure is stabilized by hydrogen bonds between secondary NH groups and O atoms of perchlorate counter-ions.     

Crystal Structure and Spectroscopic Properties of <Emphasis Type="Italic">trans</Emphasis>-Dibromobis(1,2-ethanediamine)chromium(III) Perchlorate

Abstract  

The crystal structure of trans-[Cr(en)₂Br₂]ClO₄ (en = 1,2-ethanediamine) has been determined by a single-crystal X-ray diffraction study at 150 K. The complex crystallizes in the space group P[`1] P\overline{1} of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.853(4), b = 8.109(5), c = 12.475(8) ?, α = 81.006(10)°, β = 77.005(10)° and γ = 74.981(10)°. The Cr atom is in a slightly distorted octahedral environment, coordinated by four nitrogen atoms of two en ligands and two bromine atoms in trans axial positions. The mean Cr–N(en) and Cr–Br bond lengths are 2.079(3) and 2.4743(10)?, respectively. The five-membered rings are in stable gauche conformations with N1–Cr1–N2 and N3–Cr2–N4 angles of 82.81(11)° and 83.67(11)°, respectively. The crystal packing is stabilized by a network of N–H···O and N–H···Br hydrogen bonds. The infrared and electronic absorption spectra are consistent with the results of X-ray crystallography.     

Strain variation in p-GaN by different spacer layers in the light emitting diodes and their microstructural and emission behaviors

InGaN/GaN multiple quantum well-based blue light emitting diodes (LEDs) with different spacer layer structures were grown by metalorganic chemical vapor deposition. Fast-Fourier-transformed high-resolution transmission electron microscopy was used to determine the influence of the strain status in the spacer layer on Mg distribution and device performance. A comparison of the (1 1¯ 0 0) planar distance showed that the high-temperature grown InGaN layer in the spacer had a high level of stored strain. This led to the formation of a continuous facet contrast induced by Mg segregation in the p-layer, which was responsible for the deterioration of the electroluminescence performance of the LEDs. These results show that the delicate control of stored strain in nitride films is important for improving the device performance.     

Synthesis and Crystal Structure of 2,13-Bis(acetamido)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0<Superscript>1.18</Superscript>,0<Superscript>7.12</Superscript>]docosane Tetrachlorocobalt(II)dihydrate

Abstract The novel ionic compound [H₂bdtd][CoCl₄] · 2H₂O (1) was prepared by the reaction between CoCl₂ and 2,13-bis(acetamido)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane (bdtd) in adjusted to pH 3.0 by 1.0 M HCl and structurally characterized. The crystals are monoclinic C2/c with a = 18.7777(9), b = 9.7356(4), c = 20.0884(9) ?, β = 109.6340(10)°, V = 3458.9(3) ?³, Z = 4. The dication H₂bdtd occupies a special position about an inversion center. The cobalt(II) atom in the anion is in a distorted tetrahedral environment with four chloride ligands. The crystal structure is stabilized by a variety of hydrogen-bonding contacts involving the dication, chloride anions and solvent water molecules. Cyclic voltammetry of [CoCl₄]²⁻ anion in 1 undergoes irreversible one-electron reduction to the Co^II/Co^I. Graphical abstract The crystal structure of the ionic compound [H₂bdtd][CoCl₄] · 2H₂O (1) consists of [H₂bdtd]²⁺ cation, [CoCl₄]²⁻ anion and water molecules joined together by ionic interaction and hydrogen bonds. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The characteristics of solid phase crystallized (SPC) polycrystalline silicon thin film transistors employing amorphous silicon process

We investigated the electrical properties of polycrystalline silicon (poly-Si) thin film transistors (TFTs) employing field-enhanced solid phase crystallization (FESPC). An n+ amorphous silicon (n+ a-Si) layer was deposited to improve the contact resistance between the active Si and source/drain (S/D) metal instead of ion doping. By using C–V measurement method, we could explain the diffused phosphorous ions (P+ ions) on the channel surface caused a negatively shifted threshold voltage (V_TH) of ?7.81 V at a drain bias of 0.1 V, and stretched out a subthreshold swing (S) of 1.698 V/dec. This process was almost compatible with the widely used hydrogenated amorphous silicon (a-Si:H) TFT fabrication process and also offers a better uniformity when compared to the conventional laser-crystallized poly-Si TFT process because of non-laser crystallization.