Substitution Of Different Groups Research Articles

Sisal cellulose paper based triboelectric nanogenerator with high performance for detection of chemical group substitution degree

Cellulose-derived materials have attracted extensive attention for applications in advanced electronics due to their abundance, low cost, light weight, and sustainability. Here, we report a paper-based triboelectric nanogenerator (TENG) which was made of sisal cellulose as the friction layer. The effects of the surface morphology, structure, and dielectric properties of sisal cellulose paper (SCP) on the output performance of SCP-TENG were discussed. It is found that the electrical output performance of the SCP-TENG can be improved and controlled by chemically modifying SCP with different polar groups of -NO2, -COCH3, -Cl, -Br, -CH3, -C2H5, which is closely related to the dielectric constant change of SCP. Among them, the dielectric constant of the nitrated SCP is the highest, and the electrical output performance of the corresponding SCP-TENG also exhibits the highest, with the short-circuit current, open-circuit voltage, charge and power density improving to 20.78 μA, 198 V, 103 nC/m2, 827.03 mW/m2, from 6.13 μA, 118 V, 53 nC/m2, and 256.97 mW/m2, respectively. Based on the linear relationship between the current intensity of the modified SCP-TENG and the degree of substitution of different groups, a chemical sensor for detecting the degree of group substitution was successfully fabricated. This work provides a new idea for broadening the application field of TENG.

Structural insights into the substrate specificity of 5-chloro-2-hydroxymuconate tautomerase CnbG

The catechol meta-cleavage pathway is widely involved in the degradation of aromatic compounds, including those halogenated aromatic hydrocarbons and their derivatives. CnbG is a kind of 4-oxalocrotonate tautomerase (4-OT) located in the catechol meta-cleavage pathway, catalyzes the ketonization of cis,cis-5-chloro-2-hydroxymuconate and cis,cis-2-hydroxymuconate to yield 5-chloro-2-oxo-3-hexene-1,6-dioate and 2-oxo-3-hexene-1,6-dioate, and contributes to the degradation of 4-chloronitrobenzene and chlorobenzene in Comamonas testosteroni CNB-1. Yet, the reason why CnbG and those 4-OTs could recognize various substrates is not well explained. Here, we determined the crystal structure of CnbG at resolution of 2.0 Å and identified that the potential substrate pocket involved in four conserved residues, residues Pro1, Arg11, Arg39 and Trp50, but not five conserved residues as those reported in other 4-OTs. We also found the four conserved residues assemble different sequence patterns in different 4-OTs, indicating their potential roles in catalysis and substrate binding. Via molecular docking, we found the 5-chloro group was clamped by two residues and extended to the solvent, indicating a substrate binding mode that could bear the substitution of different groups in the 5-position. Our work extends the knowledge of the substrate specificity of enzymes in the catechol meta-cleavage pathway.

New asymmetric bisthiocarbohydrazones and their mixed ligand nickel(II) complexes: Synthesis, characterization, crystal structure, electrochemical-spectroelectrochemical property, antimicrobial and antioxidant activity

New asymmetric isatin bisthiocarbohydrazone ligands were synthesized by the condensation of 3,5-dibromosalicylaldehyde, 3,5-dichlorosalicylaldehyde and 3-bromo-5-chlorosalicylaldehyde with isatin monothiocarbohydrazone. New mixed ligand Ni(II) complexes were synthesized from these ligands using triphenylphosphine (PPh3) as a secondary ligand. The synthesized ligands and complexes were characterized by elemental analysis, FT-IR, 1H NMR, UV–Vis spectroscopy and mass spectrometry techniques, along with conductivity measurements. The ligands bind to the Ni(II) ion as ONS donors. The fourth coordination site is completed by the secondary ligand PPh3. The single crystal structures of one ligand and one complex were also resolved by X-ray crystallography. The electrochemical responses of the ligands and their complexes were determined and the results were evaluated to illustrate the influence of the substitution of different groups on the ligands. While the free ligands only give one oxidation peak, two oxidation peaks are observed for the Ni(II) complexes. Complexation of the ligands with the Ni(II) ion considerably affected the in-situ spectroelectrochemical responses of the ligands. Finally, the in vitro antioxidant and antimicrobial activities of the synthesized compounds were determined.

A simple computational approach for pKa calculation of organosulfur compounds

The present work is related to predicting the pKa values of organosulfur compounds through the density functional theory (DFT). In this study, 22 organosulfur compounds were considered to calculate the theoretical pKa values. The main emphasis was given on the substitution of different groups on the sulfur atom. The computations were performed in the presence of dimethyl sulfoxide (DMSO) as solvent. Experimentally, the order of increase of acidity is; sulfides < sulfoxides < sulfones. The herein computed pKa values also follow the same order. The theoretical pKa values were computed using the DFT method B3LYP, with the basis sets 6-31G(d), 6-31+G(d,p) and the IEFPCM bulk solvation model. The majority of the pKa values computed through the diffuse function basis set were in excellent agreement with the experimental ones. Hence this computational approach, B3LYP/6-31+G(d,p)/IEFPCM, could be utilized to predict the pKa values of these types of organosulfur compounds.

Optical Properties of Some Oligothiophene Derivatives: DFT Study

Polythiophenes are of considerable interest as synthetic metals. The optical properties of polythiophenes can be easily affected by alkyl chain or other side groups to the thiophene ring. The effect of polymerization degree on the energy gap was studied in the case of polythiophene as a conjugated polymer at B3LYP/6-31+G(3d,3p) level of theory. Up to n = 16 could be confident that this degree of polymerization represents the bulk of polymer. The effect of the substitution of different groups in functionalized-bithiophene and terthiophene on the polarizability was studied. The correlation study was performed between descriptors representing the molecular structure and refractive index for the set of 9 oligothiophenes. Three descriptor models including energy gap, polarizability and heat of formation were developed to estimate the refractive index with R 2 = 0.81 and S = 0.068 by multi-linear regression analysis. The obtained model was used to predict the refractive indices of other six oligothiophenes. The model may be improved to predict the refractive index of the other oligothiophene derivatives.

Design of new and potent diethyl thiobarbiturates as urease inhibitors: a computational approach.

Urease is an important enzyme both in agriculture and medicine research. Strategies based on urease inhibition is critically considered as the first line treatment of infections caused by urease producing bacteria. Since, urease possess agro-chemical and medicinal importance, thus, it is necessary to search for the novel compounds capable of inhibiting this enzyme. Several computational methods were employed to design novel and potent urease inhibitors in this work. First docking simulations of known compounds consists of a set of arylidine barbiturates (termed as reference) were performed on the Bacillus pasteurii (BP) urease. Subsequently, two fold strategies were used to design new compounds against urease. Stage 1 comprised of the energy minimization of enzyme-ligand complexes of reference compounds and the accurate prediction of the molecular mechanics generalized born (MMGB) interaction energies. In the second stage, new urease inhibitors were then designed by the substitution of different groups consecutively in the aryl ring of the thiobarbiturates and N, N-diethyl thiobarbiturates of the reference ligands.. The enzyme-ligand complexes with lowest interaction energies or energies close to the calculated interaction energies of the reference molecules, were selected for the consequent chemical manipulation. This was followed by the substitution of different groups on the 2 and 5 positions of the aryl ring. As a result, several new and potent diethyl thiobarbiturates were predicted as urease inhibitors. This approach reflects a logical progression for early stage drug discovery that can be exploited to successfully identify potential drug candidates.

Synthesis of 3,4-dihydro-2H-1,2,4-benzo-thiadiazine 1,1-dioxide derivatives as potential allosteric modulators of AMPA/kainate receptors.

A series of 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide derivatives were synthesized and evaluated for their activity as allosteric modulators of kainate-activated currents in primary cultures of cerebellar granule neurons. Substitution of different groups at the 3-position of the benzothiadiazine ring distinguished between positive and negative allosteric modulatory properties.

Synthesis, nicotinic acetylcholine receptor binding, and antinociceptive properties of 2-exo-2-(2'-substituted-3'-phenyl-5'-pyridinyl)-7-azabicyclo[2.2.1]heptanes. Novel nicotinic antagonist.

A series of 2'-substituted-3'-phenyl epibatidine analogues were synthesized and evaluated for inhibition of binding at nicotine acetylcholine receptors and for antinociceptive properties in mice. The introduction of a bulky phenyl group at the 3'-position exerted a profound influence on both receptor binding and antinociceptive effects. Substitution of different groups at the 2'-position distinguished between agonist and antagonist properties. These results demonstrate that structural requirements for receptor activities and recognition are distinctively different.

N-nitrosamines and their effects on the level of glutathione, glutathione reductase and glutathione S-transferase activities in the liver of male mice.

The present study investigates the influence of different chemical structure of N-nitroso compounds on the hepatic level of reduced glutathione (GSH), glutathione reductase (GSH-R) and glutathione S-transferase (GST) activities in the liver of male Balb/C mice after treatment with 20 mg/kg body weight of each compound for 1 h as a single dose. The level of reduced glutathione decreased significantly between 37 and 70% after the treatment of male mice with ethylbutylnitrosamine (-37%), diphenylnitrosamine (-50%), propylbutylnitrosamine (-52%), diethylnitrosamine (-54%), ethylmethylnitrosamine (-55%), and dibutylnitrosamine (-70%), whereas, methylpropylnitrosamine increased the level of GSH by 71%. All the N-nitrosamine compounds tested increased the activity of glutathione reductase except ethylmethylnitrosamine had no effect. The activity of glutathione S-transferase activity was inhibited after treatment of the male mice with diphenylnitrosamine (-60%), dibutylnitrosamine (-60%), and methylpropylnitrosamine (-81%), while, ethylmethylnitrosamine and ethylbutylnitrosamine had no effect on such activity. On the other hand, diethylnitrosamine increased the activity of glutathione S-transferase by 50%. It can be postulated from this study that the chemical structure of N-nitrosamines plays a significant role in the alteration of GSH level and GSH metabolizing enzymes, since the substitution of different groups on the nitroso group was found to be capable of causing an alteration in such activities.

8-Hydroxyguanosine and 8-methoxyguanosine possess immunostimulating activity for B lymphocytes

The present paper extends previous observations of Goodman and Weigle (M. G. Goodman and W. O. Weigle, J. Immunol., 128, 2399, 1982) and describes the activation of B lymphocytes by a number of C-8-substituted guanine ribonucleosides. 8-Hydroxyguanosine stimulates both proliferation and differentiation of murine B cells while 8-methoxyguanosine stimulates only differentiation and 8-aminoguanosine has no discernible effect on B-cell activation. The former two compounds also increase the magnitude of the antibody response to the type 2 antigen trinitrophenyl-AECM-Ficoll. These data demonstrate that guanosine, which is itself inhibitory to murine B cells, is converted into an immunostimulatory molecule after substitution at its C-8 position with methoxy or hydroxy groups and the bromo or mercapto group is not essential for conferring biological activity to this nucleoside. However, our data also suggest that substitution of different groups at the C-8 position does influence the biological activity of this molecule.