scholarly journals Cyclic siloxanes conjugated with fluorescent aromatic compounds as fluoride sensors

2020 ◽  
Vol 1 (9) ◽  
pp. 3358-3368
Author(s):  
Nicha Prigyai ◽  
Supphachok Chanmungkalakul ◽  
Sutthiroj Thanyalax ◽  
Mongkol Sukwattanasinitt ◽  
Vuthichai Ervithayasuporn
Keyword(s):  
Organic Solvents ◽  
Aromatic Compounds ◽  
Blue Shift ◽  
Enhanced Fluorescence ◽  
Fluoride Ions ◽  
Cyclic Siloxanes

When cyclic siloxanes were exposed to fluoride ions, a blue-shift and enhanced fluorescence emissions appeared in most organic solvents.

Analysis of the Visual Spectrum of Methyl Orange in Solvents and in Hydrophobic Binding Sites

1973 ◽  
Vol 51 (4) ◽  
pp. 628-635 ◽  
Author(s):  
Richard L. Reeves ◽  
Robert S. Kaiser ◽  
Mary S. Maggio ◽  
Edward A. Sylvestre ◽  
William H. Lawton
Keyword(s):  
Hydrogen Bonding ◽  
Methyl Orange ◽  
Organic Solvents ◽  
Absorption Maximum ◽  
Low Frequency ◽  
Blue Shift ◽  
Frequency Component ◽  
High Frequency Component ◽  
Surfactant Micelle ◽  
Aqueous Solvent

The absorption curves of methyl orange (MO) and analogous p-aminophenylazobenzenes in organic and aqueous organic solvents are shown to consist of two severely overlapping bands. The curves have been resolved into two skewed component bands using a regression method. The blue shift of the absorption maximum obtained when organic solvents are added to aqueous solutions of MO, or when MO is bound to bovine serum albumin or a surfactant micelle, is the result of a change in relative intensities of the component bands. The low-frequency component is assigned to a π1 → π1* transition of a solvate in which there is specific hydrogen-bonding interaction between solvent and the azo nitrogens, and the high-frequency component to a π1 → π1* transition of a solvate in which the interaction is absent. The low-frequency component is favored by aqueous solvent compositions and by low temperatures. The free energies of interconversion of the species in various hydrogen-bonding solvents are correlated by the solvent surface tension but not by the dielectric constant. The results show that the shift in absorption maximum accompanying binding to a protein or micelle should be interpreted as a shift in an equilibrium rather than as a shift in transition energy.

Synthesis of Fluorinated Aromatic Compounds by One-Pot Benzyne Generation and Nucleophilic Fluorination

2014 ◽  
Vol 67 (3) ◽  
pp. 475 ◽  
Author(s):  
Takashi Ikawa ◽  
Shigeaki Masuda ◽  
Tsuyoshi Nishiyama ◽  
Akira Takagi ◽  
Shuji Akai
Keyword(s):  
Aromatic Compounds ◽  
Biologically Active ◽  
Reaction Conditions ◽  
Fluoride Ions ◽  
One Pot ◽  
Substituted Benzenes ◽  
Fluorinated Aromatic Compounds ◽  
Nucleophilic Fluorination ◽  
Sequential Reactions

The fluorination of substituted benzenes using fluoride ions under mild reaction conditions has been one of the most important challenges for the synthesis of biologically active fluorinated aromatic compounds; however, only a few synthetically useful methods are known. In this paper, it is reported that the nucleophilic fluorination of benzynes, generated from either 2-(trialkylsilyl)phenyl nonafluorobutanesulfonates or 2-(trialkylsilyl)phenols, meets this challenge. In particular, the fluorination starting from 2-(trialkylsilyl)phenols for fabricating aryl fluorides involves three sequential reactions in one-pot: the nonaflylation of phenols, benzyne generation, and nucleophilic fluorination of the benzynes. The regioselectivities of these reactions are controlled by the substituents at the C3-position of the benzynes.

scholarly journals Lignin Peroxidase Oxidation of Aromatic Compounds in Systems Containing Organic Solvents

1994 ◽  
Vol 60 (2) ◽  
pp. 459-466 ◽  
Author(s):  
Rafael Vazquez-Duhalt ◽  
Donald W. S. Westlake ◽  
Phillip M. Fedorak
Keyword(s):  
Organic Solvents ◽  
Lignin Peroxidase ◽  
Aromatic Compounds ◽  
Peroxidase Oxidation

scholarly journals Counterbalance of Stability and Activity Observed for Thermostable Transaminase from Thermobaculum terrenum in the Presence of Organic Solvents

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1024
Author(s):  
Ekaterina Yu. Bezsudnova ◽  
Alena Yu. Nikolaeva ◽  
Sergey Y. Kleymenov ◽  
Tatiana E. Petrova ◽  
Sofia A. Zavialova ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Organic Solvents ◽  
Hydration Shell ◽  
Tryptophan Fluorescence ◽  
Blue Shift ◽  
Industrial Applications ◽  
Thermostable Enzyme ◽  
Fine Tuning ◽  
Enzyme Analysis ◽  
Salt Bridges

Pyridoxal-5’-phosphate-dependent transaminases catalyze stereoselective amination of organic compounds and are highly important for industrial applications. Catalysis by transaminases often requires organic solvents to increase the solubility of reactants. However, natural transaminases are prone to inactivation in the presence of water-miscible organic solvents. Here, we present the solvent tolerant thermostable transaminase from Thermobaculum terrenum (TaTT) that catalyzes transamination between L-leucine and alpha-ketoglutarate with an optimum at 75 °C and increases the activity ~1.8-fold upon addition of 15% dimethyl sulfoxide or 15% methanol at high but suboptimal temperature, 50 °C. The enhancement of the activity correlates with a decrease in the thermal denaturation midpoint temperature. The blue-shift of tryptophan fluorescence suggested that solvent molecules penetrate the hydration shell of the enzyme. Analysis of hydrogen bonds in the TaTT dimer revealed a high number of salt bridges and surface hydrogen bonds formed by backbone atoms. The latter are sensitive to the presence of organic solvents; they rearrange, conferring the relaxation of some constraints inherent to a thermostable enzyme at low temperatures. Our data support the idea that the counterbalance of stability and activity is crucial for the catalysis under given conditions; the obtained results may be useful for fine-tuning biocatalyst efficiency.

Extraction of Essential oils from Cymbopogon citratus using Organic solvents

2021 ◽  
pp. 5709-5712
Author(s):  
Usharani B.
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Organic Solvents ◽  
Aromatic Compounds ◽  
Anticancer Agent ◽  
Vital Role ◽  
Phytochemical Analysis ◽  
Geometric Isomers ◽  
Cymbopogon Citratus ◽  
The Common

Essential oils are extracted from diverse plants and used in medicinal field for diverse conditions. The presence of unique aromatic compounds imparts aroma and medicinal values. Essential oil plays a vital role in pharmaceutical, cosmetics and also acts as rejuvenate. Though there are various plants from which essential oil are extracted, our study focuses on the extraction and comparison of the phytochemicals released from the fresh leaves of Cymbopogon citratus using two different organic solvents; (a). hexane (b) hexane and toluene in the ratio 1:1. Extraction was performed for 16 hours in Soxhlet extractor. The amount of oil obtained was weighed in both extractions and subjected to GC MS for phytochemical analysis. Results revealed that when the solvents hexane and toluene in the ratio 1:1 was used it gave a better yield of 3% from 5 gram of fresh leaves, while hexane yielded only 1.5%. The GC-MS analysis revealed that the compound released from both extractions are of diverse medicinal values and can be used in aromatherapy as rejuvenate. The compounds nerol (2,6 octadienal, 3,7 dimethyl.Z) and geraniol (2,6 octadienal, 3,7 dimethyl) are the common phytochemicals extracted .Nerol and geraniol are geometric isomers. Geraniol is reported as an efficient anticancer agent with additional properties of analgesic, antinflammatory and antiseptic values. Nerol is used as a fragrance. The compound 1 acetyl 4 hydroxy pyrrolidine 2 one is extracted when hexane and toluene were used for extraction in the ratio 1:1. It is reported to be anti-rheumatic and effective in the treatment of hips and joints. Hence it can be concluded that hexane and toluene in the ratio 1:1 can be used for extraction of oil considering its medicinal values and the increased % of extraction rather than using hexane alone.

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