Photo-catalytic activity of cationic zinc(II) complexes of phthalocyanine and porphyrazine derivatives loaded on the surface of silica gel

Cationic 2,9,16,23-tetra(3-N,N,N-trimethylaminoethyloxy)phthalocyaninatozinc(II) (complex 1) and 22,23-di(4-N,N,N-trimethylaminophenyl)benzo[b]-7,8,12,13,17,18-hexa(4-t-butylphenyl) porphyrazinatozinc(II) (complex 2) were loaded on the surface of silica gel by use of an electrostatic interaction with deprotonated silanol groups of silica gel. While complex 1 formed its dimer with increase in the amount of the complex in the composite, complex 2 hardly formed the dimer in the composite due to the steric hindrance of its peripheral substituents. 1,3-diphenylisobenzofuran was photo-oxidized using the composites as the sensitizer in aerated methanol. The reaction proceeded with singlet dioxygen generated by the visible-light irradiation upon the sensitizer. While the initial reaction rate with the composite of complex 2 steadily increased in accordance with increase in the amount of the complex, that with the composite of complex 1 at first increased, but subsequently decreased due to the formation of the photo-inactive dimer. Bilirubinditaurate was also photo-oxidized using the composites as the sensitizer in an aerated aqueous solution. The reaction proceeded with superoxide instead of singlet dioxygen. The relationship between the initial reaction rate and the amount of the complex was similar to that in methanol.

Download Full-text

Layer-Like Zeolite X as Catalyst in a Knoevenagel Condensation: The Effect of Different Preparation Pathways and Cation Exchange

Catalysts ◽

10.3390/catal11040474 ◽

2021 ◽

Vol 11 (4) ◽

pp. 474

Author(s):

Jan-Paul Grass ◽

Katharina Klühspies ◽

Bastian Reiprich ◽

Wilhelm Schwieger ◽

Alexandra Inayat

Keyword(s):

Catalytic Activity ◽

Reaction Rate ◽

Knoevenagel Condensation ◽

Ethyl Cyanoacetate ◽

Reaction Rates ◽

Initial Reaction Rate ◽

Comparative Investigation ◽

Morphological Properties ◽

Initial Reaction ◽

Zeolite X

This study is dedicated to the comparative investigation of the catalytic activity of layer-like Faujasite-type (FAU) zeolite X obtained from three different synthesis routes (additive-free route, Li2CO3 route, and TPOAC route) in a liquid-phase Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate to ethyl trans-α-cyanocinnamate. It is shown that the charge-balancing cations (Na+ and K+) and the morphological properties have a strong influence on the apparent reaction rate and degree of conversion. The highest initial reaction rate could be found for the layer-like zeolite X synthesised by the additive-free route in the potassium form. In most cases, the potassium-exchanged zeolites enabled higher maximum conversions and higher reaction rates compared to the zeolite X catalysts in sodium form. However, very thin crystal plates (below 100 nm thickness), similar to those obtained in the presence of TPOAC, did not withstand the multiple aqueous ion exchange procedure, with the remaining coarse crystals facilitating less enhancement of the catalytic activity.

Download Full-text

Assessing the Activity of Lewis Bases Organocatalysts in Halonium-Induced Carbocyclization Reactions

Synlett ◽

10.1055/s-0036-1591982 ◽

2018 ◽

Vol 29 (09) ◽

pp. 1181-1186 ◽

Cited By ~ 1

Author(s):

Charlotte Grandclaudon ◽

Mirko Ruamps ◽

Raphaël Duboc ◽

Véronique Michelet ◽

Patrick Toullec

Keyword(s):

Catalytic Activity ◽

High Activity ◽

Reaction Rate ◽

Fold Increase ◽

Initial Reaction Rate ◽

Initial Reaction ◽

Lewis Bases ◽

Background Reaction

Lewis bases were evaluated as catalysts for halocarbocyclization reactions of alkynylstyrenes and a cinnamylaniline derivative. Phosphines and phosphorus chalcogenides exhibited high activity for the conversion of alkynylstyrenes in the presence of N-halosuccinimides with up to a 30-fold increase of the initial reaction rate with respect to the background reaction. Phosphorus sulfides and selenides showed the best catalytic activity for the iodocarbocyclization of a cinnamylaniline derivative in the presence of diiodohydantoin. An asymmetric variant of the iodocarbocyclization reaction of an alkynylstyrene using a chiral phosphorus selenide resulted in a modest enantioselectivity.

Download Full-text

Immobilization of cationic zinc(II) complexes of phthalocyanine and unsymmetrical porphyrazine in mesoporous MCM-41 silica, and photo-catalytic activity of the composites

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424606000582 ◽

2006 ◽

Vol 10 (10) ◽

pp. 1212-1218 ◽

Cited By ~ 4

Author(s):

Kuninobu Kasuga ◽

Makoto Imai ◽

Hiroyuki Irie ◽

Hidekazu Tanaka ◽

Takashi Ikeue ◽

...

Keyword(s):

Reaction Rate ◽

Pore Diameter ◽

Nitrogen Adsorption ◽

Initial Reaction Rate ◽

Initial Reaction ◽

Photo Catalytic Activity ◽

Surface Areas ◽

Specific Surface Areas ◽

Nitrogen Adsorption Isotherms ◽

Mcm 41

Cationic 2,9,16,23-tetrakis(3- N , N , N -trimethylaminoethyloxy)phthalocyaninatozinc(II) and 20,21-bis(4- N , N , N -trimethylaminophenyl)-4,5,9,10,14,15-hexakis(4-t-butylphenyl)porphyrazinatozinc(II) were immobilized in MCM-41 silica by the use of an electrostatic interaction with the deprotonated silanol groups of MCM-41. From nitrogen adsorption isotherms, specific surface areas were estimated as 1031 and 702 m2.g−1 for MCM-41 and the composite of 2,9,16,23-tetrakis(3- N , N , N -trimethylaminoethyloxy)phthalocyaninatozinc(II), respectively. From pore-size distribution curves, the maximum pore diameter of MCM-41 and the composite were also estimated as 3.24 and 3.10 nm, respectively. These results revealed that 2,9,16,23-tetrakis(3- N , N , N -trimethylaminoethyloxy)phthalocyaninatozinc(II) was immobilized in the mesopores of MCM-41. While 2,9,16,23-tetrakis(3- N , N , N -trimethylaminoethyloxy)phthalocyaninatozinc(II) formed a dimer with increase in the amount of the complex in the composite, 20,21-bis(4- N , N , N -trimethylaminophenyl)-4,5,9,10,14,15-hexakis(4-t-butylphenyl)porphyrazinatozinc(II) only slightly formed a dimer in the composite, due to steric hindrance of its peripheral substituents. 1,3-diphenylisobenzofuran was photo-oxidized using the composites as the sensitizer in aerated acetonitrile. The reaction proceeded with singlet dioxygen generated by visible-light irradiation of the sensitizers. While the initial reaction rate with the composite of 20,21-bis(4- N , N , N -trimethylaminophenyl)-4,5,9,10,14,15-hexakis(4-t-butylphenyl)porphyrazinatozinc(II) increased in proportion to the increase in the amount of the complex, the initial reaction rate with the composite of 2,9,16,23-tetrakis(3- N , N , N -trimethylaminoethyloxy)phthalocyaninatozinc(II) at first increased, but subsequently decreased due to the formation of the photo-inactive dimer.

Download Full-text

Photocatalytic Degradation of Caffeine in a Solar Reactor System

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2017-0126 ◽

2018 ◽

Vol 16 (10) ◽

Cited By ~ 2

Author(s):

Raúl Luna ◽

Carolina Solis ◽

Nayeli Ortiz ◽

Aurora Galicia ◽

Francisca Sandoval ◽

...

Keyword(s):

Aqueous Solution ◽

Organic Compound ◽

Reaction Rate ◽

Initial Reaction Rate ◽

Initial Reaction ◽

Solar Reactor ◽

Photocatalytic Effect ◽

Short Period ◽

The World ◽

Degussa P25

AbstractIn this paper, solar photodegradation of caffeine in aqueous solution was studied, this organic compound is the most consumed stimulant around the world. The degradation experiments were carried outdoors in a solar reactor and Evonik-Degussa P25 TiO2was used as catalyst. The photochemical and photocatalytic effect were tested in aqueous solutions of caffeine. Experimental results indicate that the organic compound is easily degraded over a very short period of time using 0.5 g L-1of catalyst. The kinetic analysis indicates that the initial reaction rate of caffeine is described by the LH-HW model. However, the original compound cannot be mineralized very fast, caffeine is converted to other organic compounds with a longer lifetime before the mineralization, converting caffeine CO2and water.

Download Full-text

Promising Immobilization of Industrial-Class Phospholipase A1 to Attain High-Yield Phospholipids Hydrolysis and Repeated Use with Optimal Water Content in Water-in-Oil Microemulsion Phase

Applied Sciences ◽

10.3390/app11041456 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1456

Author(s):

Yusuke Hayakawa ◽

Ryoichi Nakayama ◽

Norikazu Namiki ◽

Masanao Imai

Keyword(s):

Water Content ◽

Reaction Rate ◽

Enzyme Reaction ◽

Initial Reaction Rate ◽

Industrial Applications ◽

Molar Ratio ◽

High Yield ◽

Initial Reaction ◽

Phospholipase A1 ◽

Repeated Use

In this study, we maximized the reactivity of phospholipids hydrolysis with immobilized industrial-class phospholipase A1 (PLA1) at the desired water content in the water-in-oil (W/O) microemulsion phase. The optimal hydrophobic-hydrophilic condition of the reaction media in a hydrophobic enzyme reaction is critical to realize the maximum yields of enzyme activity of phospholipase A1. It was attributed to enzymes disliking hydrophobic surroundings as a special molecular structure for reactivity. Immobilization of PLA1 was successfully achieved with the aid of a hydrophobic carrier (Accurel MP100) combination with the treatment using glutaraldehyde. The immobilized yield was over 90% based on simple adsorption. The hydrolysis reaction was kinetically investigated through the effect of glutaraldehyde treatment of carrier and water content in the W/O microemulsion phase. The initial reaction rate increased linearly with an increasing glutaraldehyde concentration and then leveled off over a 6% glutaraldehyde concentration. The initial reaction rate, which was predominantly driven by the water content in the organic phase, changed according to a typical bell-shaped curve with respect to the molar ratio of water to phospholipid. It behaved in a similar way with different glutaraldehyde concentrations. After 10 cycles of repeated use, the reactivity was well sustained at 40% of the initial reaction rate and the creation of the final product. Accumulated yield after 10 times repetition was sufficient for industrial applications. Immobilized PLA1 has demonstrated potential as a biocatalyst for the production of phospholipid biochemicals.

Download Full-text

Co-processing of hydrodeoxygenation and hydrodesulfurization of phenol and dibenzothiophene with NiMo/Al2O3–ZrO2 and NiMo/TiO2–ZrO2 catalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0148 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jesús Andrés Tavizón Pozos ◽

Gerardo Chávez Esquivel ◽

Ignacio Cervantes Arista ◽

José Antonio de los Reyes Heredia ◽

Víctor Alejandro Suárez Toriello

Keyword(s):

Active Sites ◽

Reaction Rate ◽

Supported Catalysts ◽

Initial Reaction Rate ◽

Initial Reaction ◽

Competition Effect ◽

Support Interaction ◽

Highly Active ◽

Metal Support Interaction ◽

Metal Support

Abstract The influence of Al2O3–ZrO2 and TiO2–ZrO2 supports on NiMo-supported catalysts at a different sulfur concentration in a model hydrodeoxygenation (HDO)-hydrodesulfurization (HDS) co-processing reaction has been studied in this work. A competition effect between phenol and dibenzothiophene (DBT) for active sites was evidenced. The competence for the active sites between phenol and DBT was measured by comparison of the initial reaction rate and selectivity at two sulfur concentrations (200 and 500 ppm S). NiMo/TiO2–ZrO2 was almost four-fold more active in phenol HDO co-processed with DBT than NiMo/Al2O3–ZrO2 catalyst. Consequently, more labile active sites are present on NiMo/TiO2–ZrO2 than in NiMo/Al2O3–ZrO2 confirmed by the decrease in co-processing competition for the active sites between phenol and DBT. DBT molecules react at hydrogenolysis sites (edge and rim) preferentially so that phenol reacts at hydrogenation sites (edge and edge). However, the hydrogenated capacity would be lost when the sulfur content was increased. In general, both catalysts showed similar functionalities but different degrees of competition according to the highly active NiMoS phase availability. TiO2–ZrO2 as the support provided weaker metal-support interaction than Al2O3–ZrO2, generating a larger fraction of easily reducible octahedrally coordinated Mo- and Ni-oxide species, causing that NiMo/TiO2–ZrO2 generated precursors of MoS2 crystallites with a longer length and stacking but with a higher degree of Ni-promotion than NiMo/Al2O3–ZrO2 catalyst.

Download Full-text

Photocatalytic oxidation of chlorophenols in the presence of manganese ions

Water Science & Technology ◽

10.2166/wst.1999.0661 ◽

1999 ◽

Vol 39 (10-11) ◽

pp. 225-230 ◽

Cited By ~ 3

Author(s):

Jong-Nan Chen ◽

Yi-Chin Chan ◽

Ming-Chun Lu

Keyword(s):

Aqueous Solution ◽

Ionic Strength ◽

Photocatalytic Oxidation ◽

Reaction Rate ◽

Removal Rate ◽

Adsorption Rate ◽

Manganese Ions ◽

Manganese Ion ◽

Cp Decomposition ◽

The Relationship

The decomposition of chlorophenols in aqueous solution with UV-illuminated TiO2 suspensions in the presence of manganese ions was studied. It was found that the removal rate of chlorophenols would be the highest at pH 3 in the presence of 1.18×10−4 M manganese ion. The effect of ionic strength on the 2-CP decomposition can be ignored in the range from 0.1 to 0.005 M for NaClO4. This study is also to explore the relationship between the adsorption rate and reaction rate. Results showed that the more the adsorption rate the more the decomposition rate for the three chlorophenols. Manganese ions can increase the photocatalytic oxidation of 2-chlorophenol in terms of DOC. The relationship between temperature and reaction rate for 2-CP is k = 0.0043T - 1.2146.

Download Full-text

T181. PROTEIN ACYL-THIOESTERASE ENZYME ACTIVITY IN THE POSTMORTEM DORSOLATERAL PREFRONTAL CORTEX IN SCHIZOPHRENIA

Schizophrenia Bulletin ◽

10.1093/schbul/sbaa029.741 ◽

2020 ◽

Vol 46 (Supplement_1) ◽

pp. S300-S301

Author(s):

Shaun Hopper ◽

James Meador-Woodruff

Keyword(s):

Prefrontal Cortex ◽

Total Protein ◽

Protein Trafficking ◽

Dorsolateral Prefrontal Cortex ◽

Reaction Rate ◽

Initial Reaction Rate ◽

Tissue Homogenate ◽

Initial Reaction ◽

Cortical Tissue ◽

Dorsolateral Prefrontal

Abstract Background The role protein trafficking and localization is a recent target of investigation in schizophrenia pathophysiology. An important mediator of protein trafficking is S-acylation, also known as S-palmitoylation, which is the reversible attachment of long chain fatty acids to cysteine residues. S-acylation is a dynamic post-translational modification that modulates hydrophobicity of proteins, regulating their membrane association and subcellular localization. Notably, we have previously reported a proteome-wide decrease in S-acylated protein levels in the dorsolateral prefrontal cortex (DLPFC) of subjects with schizophrenia. One potential mechanism of decreased S-acylation is increased removal of acyl groups from proteins by protein acyl-thioesterase enzymes (PATs). Here we describe the optimization of an assay to measure the activity of the PAT family of enzymes in human postmortem cortical tissue and use the assay to address our hypothesis that PAT activity is increased in the DLPFC of subjects with schizophrenia. Methods To determine PAT activity, tissue homogenate was incubated with 4-methylumbelliferyl-6-thio-palmitate-β-D-glucopyranoside (4MU-Gluc-Palm) and 1U of exogenous β-glucosidase (to hydrolyze the 4MU-Gluc reaction intermediary). Released 4MU was excited at 360 ± 40 nm and fluorescent emission was measured, per minute, at 460 ± 40 nm. To determine the relationship between initial reaction rate and amount of enzyme, the initial reaction rate using 300 µM 4MU-Gluc-Palm was measured in homogenate containing 1 – 10 µg of total protein from the DLPFC of a subject with no history of psychiatric illness. The PAT activity of DLPFC homogenate boiled for 30 min and total protein homogenate from lymphocytes were measured as negative and positive control reactions, respectively. To estimate the maximum reaction rate (Vmax) and the concentration of 4MU-Gluc-Palm which achieved ½ Vmax (Km; a measure of enzyme-substrate affinity) the initial reaction rate was calculated in the presence of 0 – 200 µM 4MU-Gluc-Palm and the Michaelis-Menten equation was fit to plots of concentration vs. initial rate. Reactions were performed on 2.5 µg total protein homogenate from the DLPFC of 24 subjects with schizophrenia and 24 non-psychiatrically ill subjects. Results A fluorescent signal, which increases with time to a plateau upon substrate depletion, is detectable in total protein homogenate from DLPFC and lymphocytes, but not boiled DLPFC homogenate. In the DLPFC the initial reaction rate is linear with total protein amount [r2 = .99; p = .007], demonstrating that the reaction is sensitive to varying amounts of enzyme in a 10-fold range. When compared between schizophrenia and control subjects, neither Vmax [t(46) = 0.756; p = .45] nor Km [t(46) = 0.780; p = .44] were statistically significantly different. Discussion Here we have demonstrated that PAT activity is measurable in human cortical tissue homogenate. Additionally, we have found no difference in the Vmax or Km of the combined PAT enzyme group in schizophrenia, providing no evidence to support our hypothesis that total PAT activity is increased in subjects with schizophrenia. This suggests that the proteome-wide decrease in S-acylated proteins in schizophrenia is caused by another mechanism, possibly increased expression or function of one or more of the specific PATs, leading to substrate specific changes in S-acylation, or a decrease in activity the acyl protein transferase enzymes, which attach acyl groups to proteins.

Download Full-text