Stability In Organic Solvents Research Articles

An Appraisal on Prominent Industrial and Biotechnological Applications of Bacterial Lipases.

Microbial lipases expedite the hydrolysis and synthesis of long-chain acyl esters. They are highly significant commercial biocatalysts to biotechnologists and organic chemists. The market size of lipase is anticipated to reach $590 million by 2023. This is all owing to their versatility in properties, including stability in organic solvents, interfacial activation in micro-aqueous environments, high substrate specificity, and activity in even non-aqueous milieu. Lipases are omnipresent and synthesized by various living organisms, including animals, plants, and microorganisms. Microbial lipases are the preferred choice for industrial applications as they entail low production costs, higher yield independent of seasonal changes, easier purification practices, and are capable of being genetically modified. Microbial lipases are employed in several common industries, namely various food manufactories (dairy, bakery, flavor, and aroma enhancement, etc.), leather tanneries, paper and pulp, textiles, detergents, cosmetics, pharmaceuticals, biodiesel synthesis, bioremediation and waste treatment, and many more. In recent decades, circumspection toward eco-friendly and sustainable energy has led scientists to develop industrial mechanisms with lesser waste/effluent generation, minimal overall energy usage, and biocatalysts that can be synthesized using renewable, low-cost, and unconventional raw materials. However, there are still issues regarding the commercial use of lipases which make industrialists wary and sometimes even switch back to chemical catalysis. Industrially relevant lipase properties must be further optimized, analyzed, and explored to ensure their continuous successful utilization. This review comprehensively describes the general background, structural characteristics, classifications, thermostability, and various roles of bacterial lipases in important industries.

Synthesis of Sumanene‐fused Acenes

AbstractSumanene derivatives fused by quinones and acenes were synthesized through Friedel‐Crafts double acylation, followed by reductive aromatization. Single‐crystal X‐ray diffraction analysis on synthesized quinone and acene derivatives revealed the one‐dimensional (1D) columnar stackings predominated by the concave‐convex alignment from sumanene moiety. The thus‐prepared sumanene‐fused acenes exhibited higher solubility to organic solvent and significant stability against aerobic oxidation than the pristine acenes.

Tunable Luminescence and Enhanced Polar Solvent Resistance of Perovskite Nanocrystals Achieved by Surface-Initiated Photopolymerization.

Colloidal lead halide perovskite nanocrystals (PNCs) have demonstrated great potential as materials of light-emitting diodes if their colloidal and compositional instability could be addressed. Herein, we reported a facile surface-initiated photopolymerization method that introduced polymers on a CsPbBr3 PNC surface to achieve improved stability and regulated halide exchange of PNCs in polar solvents. Synthetic polymers grafted from the surface of an individual PNC surface stabilized the PNCs, in which the multidentate linkage initiators and the extending polymers were two essential factors. The polymer-grafted PNCs showed composition-dependent colloidal dispersity and structural stability in various polar organic solvents and aqueous condition. It was found that changing the polarity of dispersing solvents effectively switched the swelling and collapsed states of surface polymers on the PNC-polymer nanoparticles, which provided an on-off mechanism to regulate the permeation of halide anions into the PNC cores. Thus, halide exchange of polymer-grafted PNCs in a good solvent for polymers varied the composition of PNCs and their emissive color, while switching the nanoparticles into a poor solvent, for example, ethanol and water, collapsed the surface polymer, prohibited the halide exchange, and consequently retained the color stability. It was demonstrated that different CsPbX3 PNCs with collapsed surface polymers could coexist into one solvent medium, achieving simultaneous emission with a white display. We believe this work provided insights into the rational functionalization of PNC materials using well-defined synthetic polymers toward tunable emission and outstanding stability in polar media.

A fabrication technique for paper-based analytical devices via two-sided patterning with thermal-transfer printer and laminator

In this study, we propose a novel technique for fabricating paper-based analytical devices (PADs) using a wax-based thermal-transfer printer and a thermal laminator, which allows prototyping and roll-to-roll mass production of PADs without utilizing widely used conventional wax printers. This fabrication scheme involves two-sided patterning to form hydrophobic barriers and an ink ribbon that contains sufficient wax content to form hydrophobic barriers without undesirable components or additives. First, a thermal-transfer printer forms positive patterns on the ink ribbon for the front and back sides of the device design. Subsequently, a laminator performs the two-sided thermal transfer of the patterns from the ink ribbon to a paper substrate and the thermal formation of hydrophobic barriers for channels. The hydrophobicity of the prepared ink is similar to that of ink used in wax printers and exhibits excellent stability in organic solvents and surfactants. Hydrophobic barriers and channels were successfully formed using various paper substrates typically used for PADs. The two-sided scheme allows the formation of 3D channels, including vertical paths in a single paper substrate. The utility of the proposed fabrication technique was demonstrated using a dip-type 3D PAD for sensing glucose.

Robust polyaniline coated microcapsules with superior thermal and solvent stability

For a microcapsule, the efficient encapsulation and retention of active ingredients as well as sufficient mechanical property is very important in many practical applications, which is still a challenging task and remains unsolved. In this work, a novel kind of polyaniline-coated microcapsule with outstanding strength, superior thermal and solvent stability was developed. In our strategy, a sulfonated polyacrylate microcapsule was firstly prepared via photopolymerization, and a dense and uniform polyaniline (PANI) layer was then applied to sulfonated microcapsule surfaces via the polymerization of aniline monomer. The presence of PANI layer prevented loss of encapsulated oil and remarkably enhanced microcapsule stability in various organic solvents which otherwise resulted in deflation and core loss of uncoated microcapsules. Compared to the uncoated shell, the PANI-coated shell postponed the beginning mass loss temperature of the microcapsule by about 100 °C. After isothermal treatment at 250 °C for 60 min, PANI-coated microcapsules exhibited only 4.5% weight loss, much lower compared with 58.2% weight loss of the uncoated microcapsule, demonstrating good core retention ability at high temperatures. In the meanwhile, the mechanical performance of the resulted PANI-coated microcapsules has also been remarkably enhanced. The Young's modulus and hardness of the PANI-coated microcapsules was 4 times and 9 times that of uncoated microcapsules.

Using Density Functional Theory and Machine Learning to Predict the Binding Energies of Metal-Organics to Organic Functional Groups for Hybrid Material Creation

Understanding chemical interactions between organic and metal-organic molecules has wide-ranging interest to the vapor deposition community for creating hybrid organic-inorganic materials via techniques such as molecular layer deposition and vapor phase infiltration (VPI). In the case of VPI, a vapor-phase metal-organic precursor is infused into the bulk of a polymer and becomes incorporated at the nanoscale through either chemical interaction with the polymer or the formation of a non-volatile species via the introduction of a co-reactant. VPI has applicability in a number of industrially relevant fields including the creation of novel organic-inorganic hybrid membranes which have shown enhanced stability in organic solvents, while retaining high permeance and selectivity. Motivated by this application, this work uses density functional theory (DFT) to explore chemical interactions occurring during the VPI of polymer of intrinsic microporosity (PIM-1, a polymeric membrane material) with trimethylaluminum (TMA) and its co-reaction with water. These computations revealed that the coordination between the polymer and metal-organic is a critical mechanism for the formation of the hybrid and its resultant solvent stability. To expand understanding of this critical characteristic and accelerate the design of organic-inorganic hybrid materials, a DFT dataset of computed binding energies was generated from suitable and representative atomic-level models of several common polymer functional groups and over 100 metal-organic precursors. From this dataset, a predictive machine learning model for the binding energy of metal-organic molecules to polymers has been developed. This predictive model, along with the chemical guidelines obtained from feature analysis, will aid the selection of potential candidates for novel organic-inorganic hybrid membranes as well as hybrid material creation as a whole.

(Digital Presentation) Electrochemical Behavior of Ionic Liquid Modified of Lithium Bis(fluorosulfonyl)Imide Based Electrolyte for Lithium-Ion Batteries

The high efficient energy storage, lithium-ion batteries (LIBs) is accounted as one of the most important storage devices to facilitate the transition of renewable energy conversion. The electrolyte component is the most important in deciding the capacity of LIBs. Lithium bis(fluorosulfonyl)imide (LiFSI) is recently considered as promising conducting electrolyte salt for LIBs because it shows enabling high voltage, high energy density, long cycle life, and accelerates the fast-charging Li-ion batteries. Generally, Additionally, LiFSI and LiPF6 based electrolyte are used in the most of commercial LIBs. Last few years, LiFSI is regarded as an alternative electrolyte to the classical LiFP6 due to its high ionic conductivity, good thermal stability, and HF free nature. In this work, the controlled mixing of ionic liquids (ILs) (imidazolium salts and pyridinium salts) in LiFSI electrolyte was carried out to enhance the ionic conductivity, thermal stability, viscosity, and solubility in organic solvents. The ILs modified LiFSI electrolyte was prepared by adding a constant 1.0 M LiFSI and varying the concentration of ILs from 5 to 20% volume in trimethyl phosphate (TMP). After the modification by ILs, the ionic conductivity of LiFSI electrolyte (10.623 mS/cm) was considerably increased as compared to LiFSI only. The flammability test of electrolyte revealed that ILs modified LiFSI electrolyte was non-flammable, indicating excellent stability in any circumstances. The prepared ILs modified LiFSI electrolyte was used to fabricate coin cell LIBs using double-coated side electrodes (both CMS graphite/Li-NCM (5:2:3) and CMS graphite/LiFePO4). From GCD analysis, the fabricated LIBs with ILs modified LiFSI electrolyte showed a significant improvement in the charging/discharging ability as compared to commercial LIBs with LiPF6 electrolyte. This study manifests that the modification of LiFSI by novel ILs would be promising to achieve highly efficient liquid electrolytes for high performance LIBs.

Poly(2-oxazoline)s as Stimuli-Responsive Materials for Biomedical Applications: Recent Developments of Polish Scientists.

Poly(2-oxazoline)s are the synthetic polymers that are the products of the cationic ring-opening polymerization (CROP) of 2-oxazoline monomers. Due to their beneficial properties, from which biocompatibility, stealth behavior, high functionalization possibilities, low dispersity, stability, nonionic character, and solubility in water and organic solvents should be noted, they have found many applications and gained enormous interest from scientists. Additionally, with high versatility attainable through copolymerization or through post-polymerization modifications, this class of polymeric systems has been widely used as a polymeric platform for novel biomedical applications. The chemistry of polymers significant expanded into biomedical applications, in which polymeric networks can be successfully used in pharmaceutical development for tissue engineering, gene therapies, and also drug delivery systems. On the other hand, there is also a need to create ‘smart’ polymer biomaterials, responsive to the specified factor, that will be sensitive to various environmental stimuli. The commonly used stimuli-responsive biomedical materials are based mostly on temperature-, light-, magnetic-, electric-, and pH-responsive systems. Thus, creating selective and responsive materials that allow personalized treatment is in the interest of the scientific world. This review article focuses on recent discoveries by Polish scientists working in the field of stimuli-responsive poly(2-oxazoline)s, and their work is compared and contrasted with results reported by other world-renowned specialists.

The preparation of stable spherical alkali lignin nanoparticles with great thermal stability and no cytotoxicity

In order to further develop the potential applications of lignin biomass, the research on lignin nanoparticles (LNPs) and their nanocomposites has attracted increasing attention. In this study, a facile and no chemical modification approach to prepare stable alkali lignin nanospheres is presented. The nanospheres around 85–125 nm were prepared through the π-π interactions between molecules in the self-assembly process. Lignin alkali was dissolved in ethylene glycol at different initial concentrations and subsequently ultrasound and dialysis treatment were conducted to prepare LNPs. The prepared LNPs had zeta potentials between −20 mV and −40 mV, and they were electrostatically stable over the pH range of 3 to 12 in aqueous solution. The chemical structure of LNPs was not significantly modified compared to lignin. Meanwhile the increased content of carboxyl and aliphatic hydroxyl groups in the LNPs structure was observed. Furthermore, the thermal stability and solubility in organic solvents (ethanol, acetone and THF) of LNPs were enhanced compared to those of lignin. In vitro cell viability evaluation indicated that the prepared LNPs had no cytotoxicity and excellent biocompatibility with mouse fibroblast. Therefore, we proposed here the production of high-quality and renewable LNPs, which will provide a novel perspective for multifunctional applications of bio-based nanomaterials.

Dynamic PEGylated phenothiazine imines; synthesis, photophysical behavior and reversible luminescence switching in response to external stimuli

Herein we report the synthesis, characterization, photophysical behavior and dynamic character of new PEGylated imine derivatives. Two PEGylated phenothiazine aldehydes were synthetised and reacted with two amines bearing sulfonamide moiety via microwave assisted synthesis to yield four imine derivatives. The imines and the aldehydes precursors were structurally characterized by NMR and FTIR spectroscopy and their self-assembly behaviour was investigated by polarized light microscopy (POM) and dynamic light scattering (DLS). Photophysical properties were investigated by UV–vis and photoluminescence spectroscopy and the quantum efficiency was determined using an integrating sphere. Dynamic character of the imine derivatives was explored by NMR and UV–vis spectroscopy in correlation with visual assessment of luminescence change. The new synthetized PEGylated imines showed solubility and stability in common organic solvents, high quantum efficiency in solution and solid state, self-assembling behaviour in ethanol, and dynamic character giving access to the reversible switch of their emission colour from green to yellow through shifting the imination equilibrium under the influence of external stimuli.

Selective luminescent sensing of teflubenzuron and oxyfluorfen by a resorcin[4]arene-based metal-organic framework

In this work, a new resorcin[4]arene-based metal–organic framework, [Zn4L(H2O)10]·10H2O, has been synthesized by incorporating Zn(II) cations and a dodecacarboxylic-functionalized resorcin[4]arene (H12L) ligand. The structure of [Zn4L(H2O)10]·10H2O was characterized using a single-crystal X-ray diffraction technique. The two-dimensional layered structures were linked to adjacent layers by hydrogen bonds to form a three-dimensional supramolecular architecture. [Zn4L(H2O)10]·10H2O exhibits excellent stability in water and various organic solvents, therefore, it was used as a luminescent probe to detect pesticides, such as teflubenzuron and oxyfluorfen. Teflubenzuron can significantly enhance the luminescence intensity of [Zn4L(H2O)10]·10H2O due to the hydrogen bond interaction, whereas oxyfluorfen can decrease the luminescence intensity of [Zn4L(H2O)10]·10H2O, which is attributed to the charge transfer and energy transfer. The luminescence mechanism was supported by the density functional theory calculations. The limit of detection for teflubenzuron and oxyfluorfen was 0.18 μM and 4.08 μM, respectively.

Water-Stable Cd-MOF with fluorescent sensing of Tetracycline, Pyrimethanil, abamectin benzoate and construction of logic gate

Due to the indiscriminate abuse of pesticides and antibiotics has caused serious threats to the environment and human and animal bodies, the detection of antibiotics and pesticides has attracted widespread attention in recent years. Herein, a novel 2D Cd (II)-MOF, [Cd(L)0.5(1,2-bimb)] (Cd-L-1,2-bimb), [H4L = 1, 1′-ethylbiphenyl −3, 3′, 5, 5′- tetracarboxylic acid, 1, 2-bimb = 1, 2-bis[(1H-imidazol-1-yl) methyl] benzene] is synthesized. Cd-L-1,2-bimb has excellent stability in different organic solvents and in the range of pH 1.1–12.5. Cd-L-1,2-bimb exhibits high selectivity, high sensitivity, and fast luminescent response to pesticides [pyrimethanil (PTH, LOD = 2.2 μM) and abamectin benzoate (AMB, LOD = 2.39 μM)] and antibiotic contaminants tetracycline (TET, LOD = 0.13 μM). Cd-L-1,2-bimb displays discriminative fluorescence when detecting AMB and PTH, and is an implication logic gate. Finally, the possible detection mechanism of Cd-L-1,2-bimb toward different pollutants is also further investigated. This MOF-based multifunctional sensor opens up new prospects for environmental monitors.

Dual role of novel hole-transporting and deep-blue emitting materials based on twisted binaphthyl

Three novel deep blue-emitting materials from binaphthyl derivatives, namely BFS, BNS and BNF, were designed and synthesized. Due to their rigid structure, all the materials exhibit high thermal stability with Td exceed 440 °C and Tg as high as 153 °C, 149 °C and 140 °C, respectively. They also show appropriate HOMO and LUMO energy level, excellent amorphous stability and outstanding solubility in common organic solvents. These novel materials are highly emissive in both solution and solid states, with deep blue emissions peaked at ∼450 nm. Deep-blue OLEDs using the novel materials as emitter resulted in efficient CE, EQE and luminance. The BFS, BNS and BNF based devices show good EL performances with the Lmax of 857 cd/m2 (CEmax of 0.3 cd/A), Lmax of 1038 cd/m2 (CEmax of 0.5 cd/A), and Lmax of 3717 cd/m2 (CEmax of 0.5 cd/A), respectively. They should be promising hole-transport and deep blue-emitting materials for OLED devices.

Vapor-Phase Infiltration of Polymer of Intrinsic Microporosity 1 (PIM-1) with Trimethylaluminum (TMA) and Water: A Combined Computational and Experimental Study.

Vapor-phase infiltration, a postpolymerization modification process, has demonstrated the ability to create organic-inorganic hybrid membranes with excellent stability in organic solvents while maintaining critical membrane properties of high permeability and selectivity. However, the chemical reaction pathways that occur during VPI and their implications on the hybrid membrane stability are poorly understood. This paper combines in situ quartz crystal microbalance gravimetry (QCM) and ex situ chemical characterization with first-principles simulations at the atomic scale to study each processing step in the infiltration of polymer of intrinsic microporosity 1 (PIM-1) with trimethylaluminum (TMA) and its co-reaction with water vapor. Building upon results from in situ QCM experiments and SEM/EDX, which find TMA remains within PIM-1 even under long desorption times, density functional theory (DFT) simulations identify that an energetically stable coordination forms between the metal-organic precursor and PIM-1's nitrile functional group during the precursor exposure step of VPI. In the subsequent water vapor exposure step, the system undergoes a series of exothermic reactions to form the final hybrid membrane. DFT simulations indicate that these reaction pathways result in aluminum oxyhydroxide species consistent with ex situ XPS and FTIR characterization. Both NMR and DFT simulations suggest that the final aluminum structure is primarily 6-fold coordinated and that the aluminum is at least dimerized, if not further "polymerized". According to the simulations, coordination of the aluminum with at least one nitrile group from the PIM-1 appears to weaken significantly as the final inorganic structure emerges but remains present to enable the formation of the 6-fold coordination species. Water molecules are proposed to complete the coordination complex without further increasing the aluminum's oxidation state. This study provides new insights into the infiltration process and the chemical structure of the final hybrid membrane including support for the possible mechanism of solvent stability.

Self-adhesive PMIA membranes with chitosan porous beads immobilized pullulanase for efficient biological aging of beer

A novel pulluanase@chitosan porous beads/Poly (m-phthaloyl-m-phenylenediamine) (PULL@CPB/PMIA) membrane with good separation and biocatalysis properties was prepared by a self-adhesive method by introducing an immobilized enzyme (PULL@CPB) onto the PMIA membrane. The combination of PULL@CPB and PMIA could increase the one-step refining of protoplasmic beer as well as the ability of biocatalysis to lower the alcohol-to-ester ratio. The experimental results showed that the addition of PULL@CPB and the increase in the ratio of EtOH/water in the coagulation bath both increased the load of pullulanase on the membrane surface, while excessive addition decreased the activity of pullulanase. Under the amount of PULL@CPB is 0.5 g·L−1 and the ratio of EtOH/water is 60%, the relative activity of pullulanase in PULL@CPB modified PMIA membrane was the highest, which was 91.7% of the initial activity. The interception rates of protein and macromolecular β-glucan were 92.2% and 87.3%, respectively, under the condition of beer flux (162.3 L·m−2·h−1). At the same time, the PULL@CPB/PMIA membrane has strong antibacterial performance and thus plays a role in extending the shelf life of beer. Compared with free pullulanase, the thermal stability, pH stability, organic solvent stability, and storing stability of immobilized pullulanase were significantly improved. The effects of PULL@CPB dosage and operating temperature on biocatalysis efficiency were discussed. The immobilized pullulanase activity on the membrane remained at 70.8% after 10 continuous uses. Therefore, the PMIA membrane is an excellent carrier of pullulanase, so its bioactive membrane has a wide range of prospects in food, medicine, and other fields.

Screening and characterizing flavone synthases and its application in biosynthesizing vitexin from naringenin by a one-pot enzymatic cascade

C-glycosylated flavonoids are important structural derivatives of flavonoids and have a variety of physiological activities. Flavone synthase is a key enzyme for producing C-glycosylated flavonoids. In this study, three flavone synthase genes were cloned, overexpressed and characterized in E. coli. By analyzing the enzymatic properties of the enzymes, Aethusa cynapium flavone synthase (AcFNS) was better than Apium graveolens flavone synthase (AgFNS) and Petroselinum crispum flavone synthase (PcFNS) in terms of catalytic ability, organic solvent tolerance and stability. Then, a one-pot enzymatic cascade was developed to synthesize vitexin from naringenin by using AcFNS, C-glycosyltransferase (TcCGT) from Trollius chinensis, and sucrose synthase (GmSUS) from Glycine max. The effects of enzyme ratios, substrate concentrations, cofactors, and reaction conditions on vitexin production were determined. The highest vitexin production reached 935.6 mg/L with a corresponding molar conversion of 78.7 % for (2 S)-naringenin. Thus, this is the first report of a one-pot enzymatic cascade for vitexin production from naringenin in vitro.

An enzyme-particle hybrid ink for one step screen-printing and long-term metabolism monitoring

Targeting the long-term monitoring of biological carbohydrate metabolism, we developed a one-step screen-printing method to fabricate electrochemical sensors using an enzyme microparticle hybrid ink. Most enzymes have low stability in high temperatures and organic solvents, making conventional enzyme modification a bottom-up procedure to be performed after electrode fabrication, resulting in inactivation and detachment in long-term work. Enzyme-loaded microparticles prepared by manganese carbonate co-precipitation had higher stability than free enzymes, which could to be mixed directly with carbon paste for direct screen-printing. Due to the co-printing immobilization and the local hydration environment in enzyme particles, the prepared electrodes exhibited higher long-term operational stability than the conventional multi-step cross-linking method. In the sensing applications, we prepared microparticles loaded with single enzyme (glucose oxidase) and dual enzymes (β-galactosidase and glucose oxidase) for glucose and lactose monitoring, respectively. Both electrodes can accurately measure the consumption of the corresponding carbohydrates throughout the cell or bacterial culture period thus providing a sensing platform for bio-metabolic monitoring and drug screening.

Different Effects of Salt Bridges near the Active Site of Cold-Adapted Proteus mirabilis Lipase on Thermal and Organic Solvent Stabilities

Organic solvent-tolerant (OST) enzymes have been discovered in psychrophiles. Cold-adapted OST enzymes exhibit increased conformational flexibility in polar organic solvents resulting from their intrinsically flexible structures. Proteus mirabilis lipase (PML), a cold-adapted OST lipase, was used to assess the contribution of salt bridges near the active site involving two arginine residues (R237 and R241) on the helix η1 and an aspartate residue (D248) on the connecting loop to the thermal and organic solvent stabilities of PML. Alanine substitutions for the ion pairs (R237A, R241A, D248A, and R237A/D248A) increased the conformational flexibility of PML mutants compared to that of the wild-type PML in an aqueous buffer. The PML mutants became more susceptible to denaturation after increasing the dimethyl sulfoxide or methanol concentration than after a temperature increase. Methanol was more detrimental to the structural stability of PML compared to dimethyl sulfoxide. These results suggest that direct interactions of dimethyl sulfoxide and methanol with the residues near the active site can have a destructive effect on the structure of PML compared with the global effect of heat on the protein structure. This study provides insight into the conformational changes within an OST enzyme with different effects on its thermal and organic solvent stabilities.

Selective and Multicyclic CO2 Adsorption with Visible Light-Driven Photodegradation of Organic Dyes in a Robust Metal-Organic Framework Embracing Heteroatom-Affixed Pores.

Pore environment modulation with polarizing groups is one of the essential prerequisites for selective carbon dioxide (CO2) adsorption in metal-organic frameworks (MOFs), wherein judicious installation of the photocatalytic feature can promise visible light-triggered degradation of toxic organic dye molecules. However, astute amalgamation of both these attributes over a single MOF is rather rare, yet much anticipated in view of sustainable applications. Pore engineering is effectively harnessed in a Zn(II)-based three-dimensional (3D) MOF, CSMCRI-16 (CSMCRI = Central Salt and Marine Chemicals Research Institute), through mixed-ligand assembly of a N-rich linker (L), 4,4'-oxybis(benzoic acid) (H2oba) ligand, and [Zn2(CO2)4N2] paddle-wheel secondary building units (SBUs). The noninterpenetrated structure contains unbound nitrogen and accessible oxygen atom-decorated porous channels and exhibits admirable stability in diverse organic solvents, open air, and at elevated temperatures. The heteroatom-decorated porous channels facilitated excellent CO2 uptake in the activated MOF (16a) with high selectivity over N2 (CO2/N2: 155.3) at 273 K. The framework further exhibits reasonable CO2 affinity and multicyclic CO2 sorption recurrence without a significant loss in the uptake capacity. Benefitting from the presence of the [Zn2(CO2)4N2] cluster in conjugation with π-conjugated organic ligands, the extended 3D network revealed an optical band gap energy of 2.55 eV, which makes the MOF an efficient photocatalyst toward the degradation of the cationic dyes crystal violet (CV) and methylene blue (MB) in the presence of a simple 40 W visible light lamp without any assistance of external oxidants. The catalyst exhibits multicyclic performance and short reaction time in addition to the fact that catalytic efficiencies (CV: 97.2%, MB: 97.8%) are comparable to those of contemporary materials.

Introducing a covalent thiol-based protected immobilized acetylcholinesterase with enhanced enzymatic performances for biosynthesis of esters

Acetylcholinesterase covalent immobilization was performed on mercaptoacetic acid-functionalized magnetic nanoparticles. Upon the thiol-based protection of the enzyme active center, its kinetics, stability, and activity in organic solvents were enhanced and its initial activity was fully recovered. The optimal results for the immobilization (i.e., yield=98.3 ± 5.2 %; enzyme loading=1.20 ± 0.06 mg mg−1) were found at an acetylcholinesterase initial concentration of 12.0 mg mL−1 and an immobilization time of 4.0 hrs. The optimum pH of both enzymes was over 7.0–9.0. The optimal temperature was measured as 40.0–45.0 and 30 ºC for immobilized and free AChE, respectively. The immobilized enzyme retained about 92.1 ± 3.0 % and 91.5 ± 3.0 % of the initial activity after 65 days and 10 cycles, respectively. The Km and Vmax were calculated as 136.2 ± 8.2 µM and 4.3 ± 0.2 µmol mg−1 min−1for the immobilized and 162.0 ± 9.7 µM and 3.63 ± 0.20 µmol mg−1 min−1for the free enzyme. The novel biocatalyst was utilized for ultra-fast esterification, for the first time, revealing 73.0 ± 2.3 % yield after 30.0 min and 85.0 ± 2.7 % after 15.0 min along with fully saving the catalytic efficiency over 6 and 8 cycles for solvent-free and solvent-controlled reactions, respectively. As a consequence, this biocatalyst is an excellent candidate for the application of the AChE enzyme in the commercial synthesis of esters.