scholarly journals Theoretical Study of Hydrogen Bond Formation in Four Rare Sugars: Gulose, Allose, Altrose, and Talose

2021 ◽  
Author(s):  
Zahrabatoul Mosapour Kotena ◽  
Mozhan Razi ◽  
Sara Ahmadi
Keyword(s):  
Closed Shell ◽  
Hydroxyl Group ◽  
Aim Analysis ◽  
Low Frequencies ◽  
Hydrogen Bond Formation ◽  
Group Orientation ◽  
Free Hydroxyl ◽  
Ft Ir ◽  
Rare Sugars ◽  
Aim And Nbo

Abstract Rare sugars are monosaccharides with tremendous potential for applications in pharmaceutical, cosmetics, nutraceutical, and flavors industries. The four rare sugars, including; gulose, allose, altrose and talose are stereoisomers that are different in the hydroxyl group orientation (axial or equatorial) on the C2-4 atoms. The DFT, AIM, and, NBO calculations were used to probe the probability of formation of internal H-bonds in four rare sugars. The AIM analysis identified that altrose and talose can form three predominantly intramolecular H-bonds, whereas gulose and allose revealed one and two H-bonds, respectively and these normal intramolecular H-bonds are mostly closed-shell interactions. The theoretical calculated O-H stretching FT-IR vibrational frequencies confirmed that the intramolecular H-bonds shifted toward low frequencies in comparison to the free hydroxyl group, which caused the red-shift. Also, the lowest IR frequency in each sugar was related to the structure with the highest stabilization energy and the most strongest intramolecular H-bonds.

scholarly journals Studies on the formation of complex oxidation and condensation products of phenols. Part III. -Rearrangements of oxidation-reduction type in the diquinone group

1933 ◽  
Vol 143 (848) ◽  
pp. 223-228 ◽  
Keyword(s):  
Hydroxyl Group ◽  
Hydrogen Atoms ◽  
Blue Colour ◽  
Highly Active ◽  
Oxidation Reduction ◽  
Intramolecular Reactions ◽  
Trimethyl Ether ◽  
Free Hydroxyl ◽  
Ethereal Oxygen ◽  
Complex Oxidation

The diquinones have been but little investigated, and as they contain two condensed highly active quinonid systems it is to be anticipated that they should be capable of interesting intramolecular reactions. When heated to 210-215º, 4 : 4'-dimethoxydiquinone is rapidly converted into a red crystalline isomeride (yield, 90%), soluble in alkali with an intense blue colour, and yielding a mono-acetate indicating the occurrence of a free hydroxyl group. Two hydrogen atoms are taken up on reduction, and the phenolic product yields a triacetate and a trimethyl ether. It follows that of the four carbonyl oxygens of 4 : 4'-dimethoxydiquinone, one has been converted into a hydroxyl group, and another which does not exhibit any functional activity, is probably present as ethereal oxygen. These results led to formula (III) as representing the product of rearrangement.

scholarly journals Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

2019 ◽  
Vol 28 (2) ◽  
pp. 73-82
Author(s):  
Oun D. Khudair ◽  
Diar A. Fatih
Keyword(s):  
Acid Chloride ◽  
Solution Method ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Ester Linkage ◽  
Amine Groups ◽  
Conventional Solution ◽  
Dipeptide Derivative

Abstract       The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.  

scholarly journals Preparation and Cytotoxic Evaluation of PGV-1 Derivative, CCA-1.1, as a New Curcumin Analog with Improved-Physicochemical and Pharmacological Properties

2021 ◽  
Author(s):  
Rohmad Yudi Utomo ◽  
Febri Wulandari ◽  
Dhania Novitasari ◽  
Beni Lestari ◽  
Ratna Asmah Susidarti ◽  
...  
Keyword(s):  
Light Exposure ◽  
Hydroxyl Group ◽  
Cytotoxic Activities ◽  
Signaling Proteins ◽  
Pharmacological Properties ◽  
Curcumin Analog ◽  
Anticancer Properties ◽  
Ft Ir ◽  
Er Alpha ◽  
Layer Chromatography

Purpose: This study aimed to challenge the anticancer potency of PGV-1 and obtain a new compound (Chemoprevention-Curcumin Analog 1.1, CCA-1.1) with improved chemical and pharmacological properties. Methods: CCA-1.1 was prepared by changing the ketone group of PGV-1 into a hydroxyl group with NaBH4 as the reducing agent. The product was purified under preparative layer chromatography and confirmed with HPLC to show about 98% purity. It was tested for its solubility, stability, and cytotoxic activities on several cancer cells. The structure of the product was characterized using 1HNMR, 13C-NMR, FT-IR, and HR-mass spectroscopy. Results: Molecular docking analysis showed that CCA-1.1 performed similar or better interaction to NF-kB pathway-related signaling proteins (HER2, EGFR, IKK, ER-alpha, and ER-beta) and reactive oxygen species metabolic enzymes (NQO1, NQO2, GSTP1, AKC1R1, and GLO1) compared with PGV-1, indicating that CCA-1.1 exhibits the same or better anticancer activity than PGV-1. CCA-1.1 also showed better solubility and stability than PGV-1 in aqueous solution at pH 1.0–7.4 under light exposure at room temperature. The cytotoxic activities of CCA-1.1 against several (10) cancer cell lines revealed the same or better potency than PGV-1. Conclusion: In conclusion, CCA-1.1 performs better chemical and anticancer properties than PGV-1 and shows promise as an anticancer agent with high selectivity.

Characterization of Catalytic Supports by Infrared Spectroscopy and ESCA

1982 ◽  
Vol 36 (4) ◽  
pp. 361-368 ◽  
Author(s):  
Larry F. Wieserman ◽  
David M. Hercules
Keyword(s):  
Infrared Spectroscopy ◽  
Surface Area ◽  
Elevated Temperatures ◽  
Silica Alumina ◽  
Free Hydroxyl ◽  
Ft Ir ◽  
Catalytic Supports ◽  
Silica And Titania

This study compares the properties of γ-alumina, silica, and titania using ESCA and in situ FT-IR. The FWHM's of the O1s and metal 2p ESCA peaks increased systematically from titania to γ alumina; the O1s/metal 2p ESCA peak area ratios were nearly equal for γ-alumina and silica. For titania, however, the value was half that obtained for γ-alumina. In situ FT-IR showed hydroxyl bands with increasing frequencies from titania to silica. Alumina and titania form carbonate-type structures after exposure to CO at elevated temperatures. Silica exhibited no additional bands after CO treatment that could be assigned to physically adsorbed CO or carbonate-type structures. At 100°C, there is a direct correlation between the specific surface area and the intensity of infrared absorbance of the free-hydroxyl and the hydrogen-bonded hydroxyl bands for silica. The intensities of the infrared bands due to matrix modes were not affected by surface area.

scholarly journals Synthesis of GO-SalenMn and Asymmetric Catalytic Olefin Epoxidation

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 824
Author(s):  
Fengqin Wang ◽  
Tiankui Huang ◽  
Shurong Rao ◽  
Qian Chen ◽  
Cheng Huang ◽  
...  
Keyword(s):  
Enantiomeric Excess ◽  
Catalytic Performance ◽  
Hydroxyl Group ◽  
Asymmetric Catalytic ◽  
Axial Coordination ◽  
Catalyst Carrier ◽  
Ft Ir ◽  
Repeated Use ◽  
Number Of Cycles ◽  
Methyl Styrene

Graphene oxide (GO) was used as a catalyst carrier, and after the hydroxyl group in GO was modified by 3-aminopropyltrimethoxysilane (MPTMS), axial coordination and immobilization with homogeneous chiral salenMnCl catalyst were carried out. The immobilized catalysts were characterized in detail by FT–IR, TG–DSC, XPS, EDS, SEM, X-ray, and AAS, and the successful preparation of GO-salenMn was confirmed. Subsequently, the catalytic performance of GO-salenMn for asymmetric epoxidation of α-methyl-styrene, styrene, and indene was examined, and it was observed that GO-salenMn could efficiently catalyze the epoxidation of olefins under an m-CPBA/NMO oxidation system. In addition, α-methyl-styrene was used as a substrate to investigate the recycling performance of GO-salenMn. After repeated use for three times, the catalytic activity and enantioselectivity did not significantly change, and the conversion was still greater than 99%. As the number of cycles increased, the enantioselectivity and chemoselectivity gradually decreased, but even after 10 cycles, the enantiomeric excess was 52%, which was higher than that of the homogeneous counterpart under the same conditions. However, compared to fresh catalysts, the yield decreased from 96.9 to 55.6%.

scholarly journals Novolac/Phenol-Containing Phthalonitrile Blends: Curing Characteristics and Composite Mechanical Properties

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 126 ◽  
Author(s):  
Hanqi Zhang ◽  
Bing Wang ◽  
Yanna Wang ◽  
Heng Zhou
Keyword(s):  
Mechanical Properties ◽  
Fracture Strain ◽  
Mechanical Test ◽  
Gelation Time ◽  
Mechanical Analysis ◽  
Curing Temperature ◽  
Hydroxyl Group ◽  
Rheological Analysis ◽  
Curing Characteristics ◽  
Ft Ir

The phenol-containing phthalonitrile resin is a kind of self-curing phthalonitrile resin with high-temperature resistance and excellent properties. However, the onefold phthalonitrile resin is unattainable to cured completely, and the brittleness of the cured product is non-negligible. This paper focuses on solving the above problems by blending novolac resin into phenol-containing phthalonitrile. Under the action of abundant hydroxyl group, the initial curing temperature and gelation time at 170 °C decrease by 88 °C and 2820 s, respectively, monitored by DSC and rheological analysis. FT-IR spectra of copolymers showed that the addition of novolac increased the conversion rate of nitrile. When the novolac mass fraction is 10%, the peak of nitrile group disappears, which means the complete reaction. The mechanical test of blends composites shows that the maximum fracture strain of 10 wt% novolac addition is 122% higher than those of neat phthalonitrile composites on account of the introduction of flexible novolac chain segments. The mechanical properties are sensitive to elevated post-cured temperature; this is consistent with the result of morphological investigation using SEM. Finally, the dynamic mechanical analysis indicated that the glass transition temperature heightened with the increase of novolac content and post-curing temperature.

Intramolecular hydrogen bonds in the sulfonamide derivatives of oxamide, dithiooxamide, and biuret. FT-IR and DFT study, AIM and NBO analysis

Tetrahedron ◽  
2010 ◽  
Vol 66 (44) ◽  
pp. 8551-8556 ◽  
Author(s):  
B.A. Shainyan ◽  
N.N. Chipanina ◽  
T.N. Aksamentova ◽  
L.P. Oznobikhina ◽  
G.N. Rosentsveig ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Nbo Analysis ◽  
Dft Study ◽  
Intramolecular Hydrogen Bonds ◽  
Ft Ir ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Aim And Nbo

Physical Stability and Lyophilization of Poly(ε-caprolactone)-b-Poly(ethyleneglycol)-b-Poly(ε-caprolactone) Micelles

2006 ◽  
Vol 6 (9) ◽  
pp. 3032-3039 ◽  
Author(s):  
Yong Hu ◽  
Yin Ding ◽  
Yuan Li ◽  
Xiqun Jiang ◽  
Changzheng Yang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Fluorescence Spectra ◽  
Physical Stability ◽  
Storage Period ◽  
Aqueous Dispersion ◽  
Hydroxyl Group ◽  
Core Shell ◽  
Ft Ir ◽  
The Stability

The stability and lyophilization of core–shell PCL-PEG-PCL micelles were investigated by fluorescence spectra, DLS, DSC, WAXD, and FT-IR. The prepared micelles were not stable when they were stored in aqueous dispersion under different condition. Their size increased in the first 20 days and decreased gradually when the storage period was extended. Lyophilization experiment showed that the cryoprotective agent (glucose) was an essential additive to protect the micelles from aggregating during the lyophilization process. After lyophilizing and re-dispersion, the PCL-PEG-PCL micelles became larger in size compared to as-prepared ones. DSC, WAXD, and IR measurements indicated the hydrogen bonding was formed between the hydroxyl group in glucose and the carbonyl group in PCL-PEG-PCL micelles. The effect of added glucose on protection of micelles from aggregation can be explained by the formation of hydrogen bonding with PCL-PEG-PCL micelles and the formation of solid glucose matrix.

Hydroxyl group orientation affects hydrolysis rates of methyl α-septanosides

2010 ◽  
Vol 51 (8) ◽  
pp. 1209-1212 ◽  
Author(s):  
Shankar D. Markad ◽  
Shawn M. Miller ◽  
Martha Morton ◽  
Mark W. Peczuh
Keyword(s):  
Hydroxyl Group ◽  
Group Orientation ◽  
Hydrolysis Rates

In Situ FT-IR Studies on the Amine-Catalyzed Urethane Reaction Kinetics of 1,3-Butanediol

2012 ◽  
Vol 472-475 ◽  
pp. 2223-2226
Author(s):  
Peng Fei Yang
Keyword(s):  
Rate Constant ◽  
Phenyl Isocyanate ◽  
Hydroxyl Group ◽  
Activation Entropy ◽  
Ir Studies ◽  
Initial Stage ◽  
Different Temperatures ◽  
Ft Ir ◽  
Kinetics Of

Phenyl isocyanate is used to react with 1,3-butanediol at different temperatures. Toluene is used as solvent and 1,4-diazabicyclo[2,2,2]octane is used as catalyst. In-situ FT-IR is used to monitor the reaction to work out rate constant, Arrhenius equation and Eyring equation. The urethane reaction has been found to be a second order reaction, and the rate constant seems different between initial stage and final stage. The activation energy (Ea), activation enthalpy (ΔH) and activation entropy (ΔS) for the urethane reaction of primary hydroxyl group are calculated out, which are 26.4 kJ•mol-1, 23.6 kJ•mol-1and -186.6 J•mol-1•k-1, respectively. They are very useful to reveal the reaction mechanism.

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