Fluorescence properties of a carminic acid-based composite embedded in a silica matrix

Self-standing macrocellular titanosilicate monolith foams are obtained using a one-pot sol-gel route and show excellent performance in the epoxidation of cyclohexene. Thanks to the High Internal Phase Emulsion (HIPE) templating method, the materials feature a high void fraction, a hierarchically porous texture and good mechanical strength. Highly dispersed Ti species can be incorporated in tetrahedral coordination the silica matrix. These characteristics allow the obtained ‘SiTi(HIPE)’ materials to reach high catalytic turnover in the epoxidation of cyclohexene. The monoliths can advantageously be used to run the reaction in continuous flow mode.<br>

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DETERMINATION OF A SUITABLE CONDITION OF GRAFT COPOLYMERIZATION OF VINYLTRIETHOXYSILANE ONTO NR TO FORM NANOMATRIX STRUCTURE

Rubber Chemistry and Technology ◽

10.5254/rct.18.81545 ◽

2018 ◽

Vol 91 (4) ◽

pp. 767-775 ◽

Cited By ~ 2

Author(s):

Yuanbing Zhou ◽

Yoshimasa Yamamoto ◽

Seiichi Kawahara

Keyword(s):

Silica Nanoparticles ◽

Graft Copolymerization ◽

Monomer Concentration ◽

Minor Component ◽

Suitable Condition ◽

Average Diameter ◽

Silica Matrix ◽

Rubber Particles ◽

Hydrolysis And Condensation ◽

Nanomatrix Structure

ABSTRACT Graft copolymerization of vinyltriethoxysilane (VTES) onto NR particles in the latex stage is a unique reaction, since it occurs together with hydrolysis and condensation of the triethoxysilane group of VTES to form a colloidal silica linking to the rubber particles. These reactions may contribute to the formation of a silica nanomatrix structure that consists of a dispersoid of rubber particles as the major component and a silica matrix as the minor component. Here, the graft copolymerization of VTES followed by hydrolysis and condensation is investigated to determine a suitable condition to prepare NR with a silica nanomatrix structure. The mechanical properties of the resulting graft copolymer are discussed in relation to the morphology, silica content, and gel content of the rubber. Based on morphological observations, NR particles with an average diameter of approximately 1 μm are well dispersed in a nanomatrix consisting of silica nanoparticles. The thickness of the silica nanomatrix increases as the monomer concentration increases, and a long incubation time generates large silica nanoparticles. The tensile strength and viscoelastic properties are significantly improved by forming the silica nanomatrix structure, with its continuous structure that prevents the NR particles from merging.

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AIE and ESIPT Schiff base ligands and corresponding Eu(III) complexes: Multiple-color and fluorescence properties

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2021.126293 ◽

2021 ◽

Vol 615 ◽

pp. 126293

Author(s):

Shuaishuai Yang ◽

Xingjing Wang ◽

Zhongqian Hu ◽

Dongcai Guo

Keyword(s):

Schiff Base ◽

Fluorescence Properties ◽

Schiff Base Ligands

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Absorbance and fluorescence properties of 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate bound to coupled and uncoupled Ca2+-ATPase of skeletal muscle sarcoplasmic reticulum.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)66593-7 ◽

1986 ◽

Vol 261 (35) ◽

pp. 16494-16501

Author(s):

M C Berman

Keyword(s):

Skeletal Muscle ◽

Sarcoplasmic Reticulum ◽

Fluorescence Properties

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Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽

10.3390/catal11040488 ◽

2021 ◽

Vol 11 (4) ◽

pp. 488

Author(s):

Katarzyna Stawicka ◽

Maciej Trejda ◽

Maria Ziolek

Keyword(s):

Coke Formation ◽

Catalytic Performance ◽

Acid Sites ◽

Silica Matrix ◽

High Concentration ◽

Active Centers ◽

Acidic Sites ◽

Glycerol Dehydration ◽

Adsorption Desorption ◽

Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

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