Mesoporous barium titanate (BT) thin films are synthesized by a surfactant‐assisted sol–gel method. The obtained mesoporous BT thin films show enhanced ferroelectricity due to the effective strains induced by mesopores. The Curie temperature (Tc) of the mesoporous BT reaches approximately 470 °C. 相似文献
A series of aggregation‐induced emission (AIE) fluorescent gelators (TPE‐Cn‐Chol) were synthesized by attaching tetraphenylethylene (TPE) to cholesterol through an alkyl chain. The properties of the gel, nano‐/microaggregate, and condensed phases were studied carefully. TPE‐Cn‐Chol molecules form AIE fluorescent gels in acetone and in DMF. Their fluorescence can be reversibly switched between the “on” and “off” states by a gel–sol phase transition upon thermal treatment. The AIE properties of aggregated nano‐/microstructures in acetone/water mixtures with different water fractions were studied by using fluorescence spectrometry and scanning electron microscopy (SEM). In different acetone/water mixtures, the TPE‐Cn‐Chol molecules formed different nano‐/microaggregates, such as rodlike crystallites and spherical nanoparticles that showed different fluorescence colors. Finally, the condensed phase behavior of TPE‐Cn‐Chol was studied by using polarizing microscopy (POM), differential scanning calorimetry (DSC), fluorescence spectrometry, fluorescence optical microscopy, and wide‐angle X ray scattering (WAXS). The clover‐shaped TPE unit introduced into the rodlike cholesterol mesogen inhibits not only the formation of a liquid‐crystal phase but also recrystallization upon cooling from the isotropic liquid phase. Very interestingly, TPE‐Cn‐Chol molecules in the condensed state change their fluorescence color under external stimuli, such as melting, grinding, and solvent fuming. The phase transition is the origin of these thermo‐, mechano‐, and vapochromic properties. These findings offer a simple and interesting platform for the creation of multistimuli‐responsive fluorescent sensors. 相似文献
Looks matter: Generally, the morphology of titania thin films is crucial for their performance, hence much effort is spent to tailor the desired morphology. X‐ray scattering enables the monitoring of the crystalline titania layer morphology during build‐up of the functional multilayer stack (see Figure). Herein evidence is provided that the morphology is preserved throughout the fabrication process.
Molecular hydrogenation catalysts have been co‐entrapped with the ionic liquid [Bmim]NTf2 inside a silica matrix by a sol–gel method. These catalytic ionogels have been compared to simple catalyst‐doped glasses, the parent homogeneous catalysts, commercial heterogeneous catalysts, and Rh‐doped mesoporous silica. The most active ionogel has been characterised by transmission electron microscopy, X‐ray photoelectron spectroscopy, and solid state NMR before and after catalysis. The ionogel catalysts were found to be remarkably active, recyclable and resistant to chemical change. 相似文献
In this work, the microextraction in packed syringe technique combined with corona discharge ion mobility spectrometry was used for determining diazinon in water samples. A new porous composite of nanoclay and polysiloxane was prepared using a sol–gel process. An amount of 2.0 mg of the sorbent was packed in a 250 μL syringe and used for extraction. A volume of 2 mL of the sample was passed through the sorbent bed, and the entrapped analyte was eluted by 25 μL of methanol. Important parameters influencing the extraction performance were investigated. Under optimum experimental conditions, the detection limit for diazinon was 0.07 ng/mL. The intra‐ and inter‐day relative standard deviations were 5.0 and 12.3%, respectively. The calibration curve was linear in the concentration range from 0.2 to 20.0 ng/mL (r2 = 0.999). The applicability of the method was demonstrated by analyzing spiked real water samples and the spiking recoveries were in the range of 95 to 106%. 相似文献
Silica glasses doped with Dy3+ were prepared by sol–gel method. The FTIR and thermo gravimetric analysis (TGA) clearly show complete densification (density = 2.2 gm/cm3) of the gels around 1000C. The fluorescence properties of Dy3+ ion are utilized to study the structural changes during the gel to glass transition of the silica xerogels. The fluorescence intensity and full width at half maximum (FWHM) of the emission bands show an increasing tendency with heat treatment. This is attributed to a glassy silica network with an asymmetric environment. The (Y/B) ratio for the Dy3+ ion is found to be less sensitive to site symmetry effects. 相似文献
Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one (pyon), 3‐hydroxypyridine (hpy) and 3‐hydroxypyridin‐2‐one (hpyon) were prepared and the solid‐state structures of (pyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ2O ,O ′)copper(II), [Cu(C10H6F3O2)2(C5H5NO)] or [Cu(tfpb‐κ2O ,O ′)2(pyon‐κO )], (I), bis(pyridin‐3‐ol‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ2O ,O ′)copper(II), [Cu(C10H6F3O2)2(C5H5NO)2] or [Cu(tfpb‐κ2O ,O ′)2(hpy‐κO )2], (II), and bis(3‐hydroxypyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ2O ,O ′)copper(II), [Cu(C10H6F3O2)2(C5H5NO2)2] or [Cu(tfpb‐κ2O ,O ′)2(hpyon‐κO )2], (III), were determined by single‐crystal X‐ray analysis. The coordination of the metal centre is square pyramidal and displays a rare example of a mutual cis arrangement of the β‐diketonate ligands in (I) and a trans‐octahedral arrangement in (II) and (III). Complex (II) presents the first crystallographic evidence of κO‐monodentate hpy ligation to the transition metal enabling the pyridine N atom to participate in a two‐dimensional hydrogen‐bonded network through O—H…N interactions, forming a graph‐set motif R 22(7) through a C—H…O interaction. Complex (III) presents the first crystallographic evidence of monodentate coordination of the neutral hpyon ligand to a metal centre and a two‐dimensional hydrogen‐bonded network is formed through N—H…O interactions facilitated by C—H…O interactions, forming the graph‐set motifs R 22(8) and R 22(7). 相似文献