Template‐Engaged Solid‐State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency

This study presents a new synthetic method for fabricating yolk@shell‐structured barium magnesium silicate (BMS) particles through a template‐engaged solid‐state reaction. First, as the core template, (BaMg)CO₃ spherical particles were prepared based on the coprecipitation of Ba²⁺ and Mg²⁺. These core particles were then uniformly shelled with silica (SiO₂) by using CTAB as the structure‐directing template to form (BaMg)CO₃@SiO₂ particles with a core@shell structure. The (BaMg)CO₃@SiO₂ particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid‐state reaction between the (BaMg)CO₃ (core) and the SiO₂ (shell) at 750 °C. During this interfacial solid‐state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO₄:Eu³⁺ phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO₄:Eu³⁺phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO₄:Eu³⁺ phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light‐reflection and ‐scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO₄:Eu³⁺ phosphor, a hydrogen environment for the solid‐state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates.     

Monolayer Co3O4 Inverse Opals as Multifunctional Sensors for Volatile Organic Compounds

Monolayers of periodic porous Co₃O₄ inverse opal (IO) thin films for gas‐sensor applications were prepared by transferring cobalt‐solution‐dipped polystyrene (PS) monolayers onto sensor substrates and subsequent removal of the PS template by heat treatment. Monolayer Co₃O₄ IO thin films having periodic pores (d≈500 nm) showed a high response of 112.9 to 5 ppm C₂H₅OH at 200 °C with low cross‐responses to other interfering gases. Moreover, the selective detection of xylene and methyl benzenes (xylene+toluene) could be achieved simply by tuning the sensor temperature to 250 and 275 °C, respectively, so that multiple gases can be detected with a single chemiresistor. Unprecedentedly high ethanol response and temperature‐modulated control of selectivity with respect to ethanol, xylene, and methyl benzenes were attributed to the highly chemiresistive IO nanoarchitecture and to the tuned catalytic promotion of different gas‐sensing reactions, respectively. These well‐ordered porous nanostructures could have potential in the field of high‐performance gas sensors based on p‐type oxide semiconductors.     

Highly selective coextraction of rhodamine B and dibenzyl phthalate based on high‐density dual‐template imprinted shells on silica microparticles

A simple one‐pot approach based on molecularly imprinted polymer shells dispersed on the surface of silica for simultaneous determination of rhodamine B and dibenzyl phthalate (DBzP) has been developed. Highly dense molecularly imprinted polymer shells were formed in the mixture of acetonitrile and toluene by the copolymerization of methacrylic acid and ethylene glycol dimethacrylate, as well as two templates, rhodamine B and dibenzyl phthalate, directed by the vinyl end groups functional monolayer at surface silica microspheres after 3‐methacryloxypropyl trimethoxysilane modification. The obtained imprinted polymer shells showed large average pore diameter (102.5 nm) and about 100 nm shell thickness. The imprinted particles also showed high imprinting factor (α_RhB = 3.52 and α_DBzP = 3.94), rapid binding kinetics, and excellent selective affinity capacity for rhodamine B and dibenzyl phthalate containing another three competitors in mixed solution. Moreover, the imprinted particles coupled with ultra high performance liquid chromatography was successfully applied to simultaneous analysis of rhodamine B and dibenzyl phthalate in two spiked beverage samples with average recoveries in the range of 88.0−93.0% for rhodamine B and 84.0–92.0% for dibenzyl phthalate with the relative standard deviation lower than 5.1%.     

Minimalistic Ditopic Ligands: An α‐S,N‐Donor‐Substituted Alkyne as Effective Intermetallic Conjugation Linker

The capability of donor‐substituted alkynes to link different metal ions in a side‐on carbon donor‐chelate coordination mode is extended from the donor centers S and P to the second period element N. The complex [Tp′W(CO)₂{η²‐C₂(S)(NHBn)}] (Tp′=hydrido‐tris(3,5‐dimethylpyrazolyl)borate, Bn=benzyl) bearing a terminal sulfur atom and a secondary amine substituent is accessible by a metal‐template synthesis. Subsequent deprotonation allowed the formation of remarkably stable heterobimetallic complexes with the [(η⁵‐C₅H₅)Ru(PPh₃)] and the [Ir(ppy)₂] moiety. Electrochemical and spectroscopic investigations (cyclic voltammetry, IR, UV/Vis, luminescence, EPR), as well as DFT calculations, and X‐ray structure determinations of the W–Ru complex in two oxidation states reveal a strong metal–metal coupling but also a limited delocalization of excited states.     

Soliton squeezing generated in an all-fiber contiguration

We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.     

Organosilica materials with 1,5-bis-(2’-ethyl)-2,4-dimethyl benzene bridging groups

Using 1,5-bis-(2-trichlorosilylethyl)-2,4-dimethyl benzene, we have obtained porous organosilica materials containing 1.5 to 100 mole % 1,5-bis-(2-ethyl)-2,4-dimethyl benzene bridging groups. We have used X-ray phase analysis, adsorption, Fourier transform IR (FTIR) spectroscopy, thermogravimetry, and temperature-programmed desorption mass spectrometry methods to study their structure and composition. We have shown that the materials obtained generally are characterized by a biporous structure and aerosol properties: large pore volume (up to 4 cm³/g) and low density (~70 mg/cm³).Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 40, No. 6, pp. 373–379, November–December, 2004.