Relaxation of excess electrons in a polar solvent

Beneficial properties of shade trees of tea plantations other than their medicinal properties have been extensively studied. This research was initiated to explore the properties of some shade trees with special emphasis on their antioxidant and antibacterial properties. Leaves from shade tree like Dalbergia sissoo (DS), Cassia siamea (CS), Derris robusta (DR), Leucaena leucocephala (LL), Acacia lenticularis (AL) and Melia azedarach (MA) were used for the study. Characterization of shade tree leaves by determination of moisture, crude fibre and ash content and tests of non polar – polar solvent extracts for steroid, tannins, cardiac glycosides and coumarin, free radical scavenging, ferric reducing power, NO scavenging activities, quantification of Flavonoids and antibacterial activity were conducted. The average moisture, crude fibre and ash percentage of shade tree plants were found to be 62.95, 11.28 and 1.86 respectively. Methanol, ethanol, acetone and ethyl acetate respectively proved to be the most potent solvent for various phytochemical extractions as it gave positive results for tests like tannin, steroid, cardiac glycosides and coumarin. AL (91.46%), DR (92.69%), LL (94.32%) and MA (93.34%) leaf extracts showed a high level of DPPH scavenging activity in their water extracts. In DS (88.11%) and CS (83.23%) maximum DPPH scavenging activity was observed in Diethyl ether and Methanol extracts respectively. Acetone extracts were more active than the water extracts in exhibiting ferric reducing power and NO scavenging activity. Summation of the quantity revealed that DS showed maximum presence of flavonoids and acetone as most potential for isolation of flavonoids. The decreasing order of summative antibacterial activity was recorded in DS, followed by CS, DR, AL, MA and LL. Chloroform showed the highest summative inhibition zone followed by ethanol, ethyl acetate, diethyl ether, acetone, water, hexane, benzene and methanol. The antioxidant and antibacterial potential of shade trees were established.

Download Full-text

The Malleable Excited States of Benzothiadiazole Dyes and Investigation of their Potential for Photochemical Control

10.26434/chemrxiv.8251568 ◽

2019 ◽

Author(s):

Caroline C. Warner ◽

andrea thooft ◽

Bryan J. Lampkin ◽

selin demirci ◽

Brett VanVeller

Keyword(s):

Excited State ◽

Excited States ◽

Polar Solvent ◽

Nonpolar Solvent ◽

Photochemical Degradation ◽

Solvent Lead ◽

Environmentally Sensitive

<p>A strategy to control the efficiency of a photocleavage reaction based on changing the nature of the excited state is presented. A novel class of photoactive compounds has been synthesized by combining the classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in a polar solvent lead to an excited state that is inoperative for photochemistry whereas excitation in a nonpolar solvent lead to an excited state that is photochemically active. A photochemical degradation appears to be the preferred process in contrast to the intended photocleavage process.</p>

Download Full-text

Photocatalytic Degradation and Antibacterial Study of Copper(II) Mustard Thiourea Complex

Current Physical Chemistry ◽

10.2174/1877946810666200221122053 ◽

2020 ◽

Vol 10 (3) ◽

pp. 229-242

Author(s):

Vandana Sukhadia ◽

Rashmi Sharma ◽

Asha Meena

Keyword(s):

Photocatalytic Degradation ◽

Skin Diseases ◽

Polar Solvent ◽

Degradation Kinetics ◽

Research Work ◽

Solvent Polarity ◽

Inhibitory Effect ◽

Mustard Oil ◽

Urea Complex ◽

Pseudo First Order Reaction

Aims: The aim of this research work is to synthesise, study and analyse photocatalytic degradation, kinetics. Background: Copper(II) mustard thio urea complex has been synthesized and characterized through FT-IR, NMR, ESR studies. Objective: Photocatalytic degradation of copper(II) mustard thio urea complex was studied in the presence of ZnO as a catalyst in the solution form, using a non polar solvent benzene and a polar solvent methanol with different compositions. Antibacterial activities of copper(II) complex have also been studied against Staphylococcus aureus. Method: O.D. was measured after different time intervals spectrophotometrically to measure the degradation of the complex. Result: Plot of 2+ log O.D. (absorbance) versus time was plotted and found to be linear. The heterogeneous photocatalysis followed pseudo-first-order reaction kinetics. The present study suggests that the CMT complex shows antibacterial activity at different concentrations. Conclusion: The rate of photocatalytic degradation of CMT complex was studied and analyzed. It has been found that the rate of degradation varies with different parameters like the concentration of complex, the amount of catalyst, light intensity, solvent polarity etc. The CMT complex derived from natural mustard oil has shown an inhibitory effect on the growth of S. aureus which may cause skin diseases.

Download Full-text

Improved biorefinery pathways of marine diatoms using a water miscible ionic liquid and its colloidal solution: efficient lipid extraction and in situ synthesis of fluorescent carbon dots for bio-imaging applications

RSC Advances ◽

10.1039/d1ra01425k ◽

2021 ◽

Vol 11 (35) ◽

pp. 21207-21215

Author(s):

Paidi Murali Krishna ◽

Veerababu Polisetti ◽

Krishnaiah Damarla ◽

Subir Kumar Mandal ◽

Arvind Kumar

Keyword(s):

Ionic Liquid ◽

Colloidal Solution ◽

Polar Solvent ◽

Lipid Extraction ◽

In Situ Synthesis ◽

Marine Diatoms ◽

Bio Imaging ◽

Partition Method ◽

Fluorescent Carbon Dots

In this study, a water-miscible ionic liquid (IL), 1-ethyl-3-methylimidazoliumacetate ([EMIM][Ac]), has been used for lipid extraction from marine diatoms Thalassiosira lundiana CSIR-CSMCRI 001 by following a non-polar solvent partition method.

Download Full-text

Ultra-stable water-dispersive perovskite QDs encapsulated by triple siloxane coupling agent system with different hydrophilic/ hydrophobic properties

Materials Chemistry Frontiers ◽

10.1039/d1qm00129a ◽

2021 ◽

Author(s):

Bingfeng Shi ◽

Jianhua Lv ◽

Ying Liu ◽

Yang Xiao ◽

Changli Lü

Keyword(s):

Quantum Dots ◽

Coupling Agent ◽

Polar Solvent ◽

Hydrophobic Properties ◽

Agent System ◽

Environmental Tolerance ◽

Perovskite Quantum Dots ◽

Improve Stability

Driven by the instability of perovskite quantum dots (PQDs), different encapsulation techniques are used to improve stability of PQDs. However, further improvements in the extreme environmental tolerance and polar solvent...

Download Full-text

Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N-Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts

Molecules ◽

10.3390/molecules26041159 ◽

2021 ◽

Vol 26 (4) ◽

pp. 1159

Author(s):

Eskedar Tessema ◽

Vijayanath Elakkat ◽

Chiao-Fan Chiu ◽

Jing-Hung Zheng ◽

Ka Long Chan ◽

...

Keyword(s):

Michael Addition ◽

Polar Solvent ◽

Addition Reaction ◽

High Yield ◽

Addition Reactions ◽

Polar Solvents ◽

Unsaturated Bond ◽

Base Catalysts ◽

Michael Additions

Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-N,N-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4-Rf-CH2OCH2-py, where Rf = C11F23). These catalysts have been synthesized and characterized by Lu’s group. The phospha-Michael addition of diisopropyl, dimethyl or triethyl phosphites to α, β-unsaturated malonates in the presence of those catalysts showed very good reactivity with high yield at 80–100 °C in 1–4.5 h with high catalytic recovery and reusability. With regard to significant catalytic recovery, sometimes more than eight cycles were observed for DMAP·Hsac adduct by using non-polar solvents (e.g., ether) to precipitate out the catalyst. In the case of the fluorous long-chained pyridine, the thermomorphic method was used to efficiently recover the catalyst for eight cycles in all the reactions. Thus, the easy separation of the catalysts from the products revealed the outstanding efficacy of our systems. To our knowledge, these are good examples of the application of recoverable organo-catalysts to the DMAP·Hsac adduct by using non-polar solvent and a fluorous long-chained pyridine under the thermomorphic mode in phospha-Michael addition reactions.

Download Full-text

Over-expression of an electron transport protein OmcS provides sufficient NADH for d-lactate production in cyanobacterium

Biotechnology for Biofuels ◽

10.1186/s13068-021-01956-4 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Hengkai Meng ◽

Wei Zhang ◽

Huawei Zhu ◽

Fan Yang ◽

Yanping Zhang ◽

...

Keyword(s):

Electron Transfer ◽

Electron Transport ◽

Lactate Production ◽

Transport Protein ◽

Dominant Form ◽

Photosynthetic Production ◽

Reducing Equivalent ◽

Excess Electrons ◽

Novel Strategy ◽

Electron Transport Protein

Abstract Background An efficient supply of reducing equivalent is essential for chemicals production by engineered microbes. In phototrophic microbes, the NADPH generated from photosynthesis is the dominant form of reducing equivalent. However, most dehydrogenases prefer to utilize NADH as a cofactor. Thus, sufficient NADH supply is crucial to produce dehydrogenase-derived chemicals in cyanobacteria. Photosynthetic electron is the sole energy source and excess electrons are wasted in the light reactions of photosynthesis. Results Here we propose a novel strategy to direct the electrons to generate more ATP from light reactions to provide sufficient NADH for lactate production. To this end, we introduced an electron transport protein-encoding gene omcS into cyanobacterium Synechococcus elongatus UTEX 2973 and demonstrated that the introduced OmcS directs excess electrons from plastoquinone (PQ) to photosystem I (PSI) to stimulate cyclic electron transfer (CET). As a result, an approximately 30% increased intracellular ATP, 60% increased intracellular NADH concentrations and up to 60% increased biomass production with fourfold increased d-lactate production were achieved. Comparative transcriptome analysis showed upregulation of proteins involved in linear electron transfer (LET), CET, and downregulation of proteins involved in respiratory electron transfer (RET), giving hints to understand the increased levels of ATP and NADH. Conclusions This strategy provides a novel orthologous way to improve photosynthesis via enhancing CET and supply sufficient NADH for the photosynthetic production of chemicals.

Download Full-text