hydroxyl groups
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2022 ◽  
Vol 48 ◽  
pp. 103996
Jinpeng Wu ◽  
Rurong Liu ◽  
Min Li ◽  
Xianyou Luo ◽  
Wende Lai ◽  

2022 ◽  
Vol 57 ◽  
pp. 101881
Ali M. Bahmanpour ◽  
Rob Jeremiah G. Nuguid ◽  
Louisa M. Savereide ◽  
Mounir D. Mensi ◽  
Davide Ferri ◽  

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 535
Wong Pooi Wen Kathy ◽  
Li Lin Ong ◽  
Surabhi Devaraj ◽  
Duc Thinh Khong ◽  
Zaher M. A. Judeh

In this study, we report on an orthogonal strategy for the precise synthesis of 3,3′-, 3,4′-, and 3,6′-phenylpropanoid sucrose esters (PSEs). The strategy relies on carefully selected protecting groups and deprotecting agents, taking into consideration the reactivity of the four free hydroxyl groups of the key starting material: di-isopropylidene sucrose 2. The synthetic strategy is general, and potentially applies to the preparation of many natural and unnatural PSEs, especially those substituted at 3-, 3′-, 4′- and 6′-positions of PSEs.

Marine Drugs ◽  
2022 ◽  
Vol 20 (1) ◽  
pp. 69
Dawei Yu ◽  
Jiayao Feng ◽  
Huimin You ◽  
Shipeng Zhou ◽  
Yan Bai ◽  

Chitosan obtained from abundant marine resources has been proven to have a variety of biological activities. However, due to its poor water solubility, chitosan application is limited, and the degradation products of chitosan oligosaccharides are better than chitosan regarding performance. Chitosan oligosaccharides have two kinds of active groups, amino and hydroxyl groups, which can form a variety of derivatives, and the properties of these derivatives can be further improved. In this review, the key structures of chitosan oligosaccharides and recent studies on chitosan oligosaccharide derivatives, including their synthesis methods, are described. Finally, the antimicrobial and antitumor applications of chitosan oligosaccharides and their derivatives are discussed.

ChemSusChem ◽  
2022 ◽  
Ya Zhang ◽  
Qiang Zhou ◽  
Peng Wang ◽  
Yue Zhao ◽  
Feng Gong ◽  

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 295
Ayesha Qayyum ◽  
Ijaz Ahmad Bhatti ◽  
Ambreen Ashar ◽  
Asim Jilani ◽  
Javed Iqbal ◽  

To eliminate imidacloprid insecticide from wastewater, nanocalcite was grafted onto the surface of pretreated polyester fabric. The process of seeding was followed by the low temperature hydrothermal method for the growth of nanocalcite for the functionalization of fabric. The goal of this study was to improve the hydrophilicity of the nanocalcite photocatalyst that had been grafted onto the surface of polyester fabric (PF) using acidic and basic prewetting techniques. The morphological characteristics, crystalline nature, surface charge density, functional groups of surface-modified nanocalcite @ PF were determined via SEM, XRD, FTIR, and Zeta potential (ZP), respectively. Characterization results critically disclosed surface roughness due to excessive induction of hydroxyl groups, rhombohedral crystal structure, and high charge density (0.721 mS/cm). Moreover, contact angle of nanocalcite @ PF was calculated to be 137.54° while after acidic and basic prewetting, it was reduced to 87.17° and 48.19°. Similarly, bandgap of the as fabricated nanocalcite was found to be 3.5 eV, while basic prewetted PF showed a reduction in band gap (2.9 eV). The solar photocatalytic mineralization of imidacloprid as a probe pollutant was used to assess the improvement in photocatalytic activity of nanocalcite @ PF after prewetting. Response surface methodology was used to statistically optimize the solar exposure time, concentration of the oxidant, and initial pH of the reaction mixture. Maximum solar photocatalytic degradation of the imidacloprid was achieved by basic prewetted nanocalcite @ PF (up to 91.49%), which was superior to acidic prewetted fabric and as-fabricated nanocalcite @ PF. Furthermore, HPLC and FTIR findings further indicated that imidacloprid was decomposed vastly to harmless species by basic prewetted nanocalcite @ PF.

Hiroki Shioya ◽  
Naoko Inoue ◽  
Masaro Yoshida ◽  
Yoshihiro IWASA

Abstract Application of self-assembled monolayers (SAMs) is a representative method of surface modification for tuning material properties. In this study we examine the influence of the surface modification by coating the Zn-polar 0001 surface of ZnO single crystal with a SAM of triptycene-based polar molecules in our own technique and investigated temperature dependences of the sheet conductance of the surface with and without the SAM. The sheet conductance at 70 K with the SAM is increased by an order of magnitude, compared to the case without the SAM. We infer that the additional electrons are introduced at the surface by the polar triptycene molecules, whose electropositive hydroxyl groups are supposed to face toward the Zn-polar surface of ZnO. The present result implies that the molecular orientation of the triptycene SAM plays a critical role on the surface properties of oxide semiconductors.

2022 ◽  
pp. 39-46
Ntai M Khoabane ◽  
Elizabeth J Grayson ◽  
Alan M Kenwright ◽  
Manoharan K Pillai

Oligosaccharides have been playing an important role in biological systems. Synthesis of oligosaccharides requires the protection from hydroxyl groups present in the corresponding monosaccharide units. The existing methods of protection have drawbacks, including formation of anomeric mixtures, change in hydrophilicity or lipophilicity and solubility of the products, participation of the protecting groups in the reactions of the core of monosaccharide units, problems associated with chemoselectivity, regioselectivity and overall stereochemical outcomes of reactions. Additionally, there has been a spectral overlap of these protecting groups with carbohydrate core, which yielded more complex spectra. Therefore, the identification and synthesis of suitable alternative protecting groups have received attention in the oligosaccharide synthesis. The objective of the present study was to synthesize various fluorinated benzyl ethers of methyl-α-D-mannopyronoside and to evaluate these ethers as the alternative protecting groups for enhancing NMR resolution in the oligosaccharide synthesis. Various fluorinated benzyl ethers of methyl-α-D-mannopyronoside were prepared through the reaction of methyl-α-D-mannopyronoside with various fluorinated benzyl bromides by using Williamson ether synthesis method. Spectral analysis of these fluorinated benzyl ethers showed that the peaks of methylene carbons shifted to a value of 10-20 parts per million (ppm) to a high field region in the 13C NMR, compared to the non-fluorinated benzyl ether. As a result, the spectral complexity decreased and enhanced the spectral resolution. In this study, we concluded that fluorinated benzyl ethers could be a suitable alternative to the non-fluorinated benzyl ethers to protect the hydroxyl groups of monosaccharides in the synthesis of oligosaccharides.

Wei-Zhuo Gai ◽  
Shi-Hu Zhang ◽  
Yang Yang ◽  
Kexi Sun ◽  
Hong Jia ◽  

Abstract Aluminum hydroxide is an eye catching and extensively researched adsorbent for fluoride removal and its defluoridation performance is closely related to the preparation method and crystalline phase. In this research, the defluoridation performances of aluminum hydroxides with different crystalline phases are compared and evaluated in terms of fluoride removal capacity, sensitivity to pH values and residual Al contents after defluoridation. It is found that the defluoridation performance of different aluminum hydroxides follows the order of boehmite > bayerite > gibbsite. The fluoride adsorption on aluminum hydroxides follows pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum defluoridation capacities of boehmite, bayerite and gibbsite are 42.08, 2.97 and 2.74 mg m−2, respectively. The pH values and FTIR analyses reveal that the ligand exchange between fluoride and surface hydroxyl groups is the fluoride removal mechanism. Different aluminum hydroxides have different surface hydroxyl group densities, which results in the different defluoridation capacities. This work provides a new idea to prepare aluminum hydroxide with outstanding defluoridation performance.

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