Functional Groups
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CATENA ◽  
2022 ◽  
Vol 209 ◽  
pp. 105811
Author(s):  
Yulin Pu ◽  
Shanxin Lang ◽  
Aobo Wang ◽  
Shirong Zhang ◽  
Ting Li ◽  
...  

2021 ◽  
Author(s):  
Regina M. Oechsner ◽  
J. Philipp Wagner ◽  
Ivana Fleischer

We report a mild, fast and convenient catalytic system for the coupling of aryl chlorides with primary, secondary, as well as previously challenging tertiary alkyl thiols using an air-stable nickel(II) precatayst in combination with the low-cost base potassium acetate at room temperature. This new catalytic system tolerates a variety of functional groups and enables the generation of thioethers for a wide range of substrates, including pharmaceutical compounds in excellent yields. Chemoselec-tive functionalization of disubstituted substrates was demonstrated. Kinetic and NMR-studies, as well as DFT computations support a Ni(0)/Ni(II) catalytic cycle and identify the oxidative addition product as the resting state. Acetate coordination and subsequent acetate facilitated formation of a thiolate complex via internal deprotonation play a key role in the catalytic cycle.


Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2132
Author(s):  
Andraž Čarni ◽  
Mirjana Ćuk ◽  
Daniel Krstonošić ◽  
Željko Škvorc

Since grasslands provide many ecosystem services, there are often different opinions on their management (e.g., agronomy, ecology, botany). Multidisciplinary research on this topic is therefore needed. This article focuses on the impact of ecological conditions, functional groups, ecological strategies, floristic composition (through habitat preference of species), major floristic gradients (presented as first two NMDS axes), and the management of forage quality. We estimated the forage quality using indicator values. All of the available vegetation plots in the region on wet and mesic meadows, managed pastures, and tall-herb meadow/pasture fringes on deeper or shallower soils (i.e., grasslands) were collected, organized in a database, and elaborated according to standard procedure. We used a widely accepted grassland classification system that uses floristic composition to define grassland types. Based on an NMDS ordination diagram and according to functional groups, ecological strategies, and habitat preferences (behavior of species) and management, we defined three major groups: mesic meadows (mowed), wet meadows (mowed), and pastures (grazed). We correlated all groups’ functional groups, ecological strategies, habitat preferences (behavior of species), major floristic gradients, management, and forage quality. We found that forage quality mainly depends on moisture conditions and that nutrients and grazing are less important. Within the grasslands under consideration, mesic meadows and mesic pastures have the highest forage quality.


Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 182
Author(s):  
Moises Bustamante-Torres ◽  
David Romero-Fierro ◽  
Belén Arcentales-Vera ◽  
Kenia Palomino ◽  
Héctor Magaña ◽  
...  

Hydrogels are attractive biomaterials with favorable characteristics due to their water uptake capacity. However, hydrogel properties are determined by the cross-linking degree and nature, the tacticity, and the crystallinity of the polymer. These biomaterials can be sorted out according to the internal structure and by their response to external factors. In this case, the internal interaction can be reversible when the internal chains are led by physicochemical interactions. These physical hydrogels can be synthesized through several techniques such as crystallization, amphiphilic copolymers, charge interactions, hydrogen bonds, stereo-complexing, and protein interactions. In contrast, the internal interaction can be irreversible through covalent cross-linking. Synthesized hydrogels by chemical interactions present a high cross-linking density and are employed using graft copolymerization, reactive functional groups, and enzymatic methods. Moreover, specific smart hydrogels have also been denoted by their external response, pH, temperature, electric, light, and enzyme. This review deeply details the type of hydrogel, either the internal structure or the external response. Furthermore, we detail some of the main applications of these hydrogels in the biomedicine field, such as drug delivery systems, scaffolds for tissue engineering, actuators, biosensors, and many other applications.


Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3665
Author(s):  
Vasilica Popescu ◽  
Ingrid Ioana Buciscanu ◽  
Melinda Pruneanu ◽  
Stelian Sergiu Maier ◽  
Angela Danila ◽  
...  

This study may open a new way to obtain the coloration of a polymer during functionalization. Two polyacrylonitrile (PAN) polymers in the form of textile fibers (Melana and Dralon L) were subjected to functionalization treatments in order to improve the dyeing capacity. The functionalizations determined by an organo-hypervalent iodine reagent developed in situ led to fiber coloration without using dyes. KIO3 was formed in situ from the interaction of aqueous solutions of 3–9% KOH with 3–9% I2, at 120 °C. The yellow-orange coloration appeared as a result of the transformations in the chemical structure of each functionalized polymer, with the formation of iodinehydrin groups. The degree of functionalization directly influenced the obtained color. The results of the Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Map and Temogravimetric Analysis (TG) plus Differential Thermal (DTA) analyses indicated the presence of new functional groups, such as iodine-oxime. The X-ray diffraction (XRD) analysis confirmed the change of the crystalline/amorphous ratio in favor of the former. The new groups introduced by functionalization make it possible to dye with classes of dyes specific to these groups, but not specific to PAN fibers, thus improving their dyeing capacity.


Metabolites ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 728
Author(s):  
Xiaowei Song ◽  
Jia Li ◽  
Mohammad Mofidfar ◽  
Richard N. Zare

Isobaric ions having the same mass-to-charge ratio cannot be separately identified by mass spectrometry (MS) alone, but this limitation can be overcome by using hydrogen–deuterium exchange (HDX) in microdroplets. Because isobaric ions may contain a varied number of exchangeable sites and different types of functional groups, each one produces a unique MS spectral pattern after droplet spray HDX without the need for MS/MS experiments or introduction of ion mobility measurements. As an example of the power of this approach, isobaric ions in urinary metabolic profiles are identified and used to distinguish between healthy individuals and those having bladder cancer.


Author(s):  
Jiancong Liu ◽  
Yanwen Liu ◽  
Zhonglei Zhang ◽  
Xiaoshu Wang ◽  
Ying Wang ◽  
...  

Schwertmannite (schw) is a common Fe-bearing mineral in the precipitation of mine wastewater and/or steel pickling wastewater. It could be easily converted to goethite and hematite via heating or hydrothermal treatment and could be used as adsorbent to remove contaminants from wastewater. Herein, the spherical schw was converted into erdite nanorod by a simple hydrothermal method with the addition of Na2S. Schw was spherical particle with a size of 0.4–1.5 [Formula: see text]m. After treatment, it was converted to erdite nanorod particles with 100 nm diameter and 200 nm length. By adding MnO2 at the MMn/Fe ratio of 1, erdite nanorod grew radially to 1–1.5 [Formula: see text]m, whereas MnO2 was reductively dissolved and recrystallized to rambergite. In the absence of Fe, MnO2 was directly transformed to octahedral alabandite. The product EN-0, prepared without MnO2, showed the optimal qmax of oxytetracycline (OTC, 7479.6 mg/g), which was 12 times that of schw. In OTC-bearing solution, erdite was unstable and automatically hydrolyzed to generate Fe–SH/Fe–OH-bearing flocs, and it exhibited abundant surface functional groups for OTC adsorption. Subsequently, the hydroxyl and amino groups on the side chain of OTC would also be complexed with the Fe–SH group to generate an OTC–Fe–S ligand, in the form of flake-like particles with a smooth surface. The formed Mn-bearing minerals, for example, rambergite and alabandite, also complexed with OTC as OTC–Mn–S ligands to form quadrangular prism with shoulder and length of 10 [Formula: see text]m and 20–100 [Formula: see text]m, respectively. Spherical schw was converted into a well-crystallized erdite nanorod with the addition of MnO2, and the product showed potential applications in OTC-bearing wastewater treatment.


Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1273
Author(s):  
Md. Afroz Bakht ◽  
Mshari. Alotaibi ◽  
Abdulrahman I. Alharthi ◽  
Israf Ud Din ◽  
Abuzer Ali ◽  
...  

A Palladium-doped silica-supported heteropoly acid (HPW) (1%Pd-HPW/SiO2) bi-functional catalyst was produced using ultrasonic and conventional procedures. Both forms of catalyst were characterized with distinct analytical approaches in order to access the advantages of each one. The presence of the required functional groups in the catalyst was confirmed using FT-IR. The crystallinity of ultrasonically generated 1%Pd-HPW/SiO2 was confirmed with XRD. The existence of necessary elements in the catalyst was also suggested by XPS and EDX data. BET was used to calculate the surface area of the ultrasonically synthesized catalyst (395 m2 g−1), and it was found to be greater than that of the non-ultrasonic synthesized catalyst (382 m2 g−1). The N2 adsorption-desorption isotherm indicated mesoporous structures. The SEM morphology at a similar magnification exhibited quite different shapes. In comparison to traditional methods, ultrasonic approaches produce higher yields in less time and use less energy. Furthermore, the effect of the preparation method of the 1%Pd-HPW/SiO2 catalyst was extensively studied with respect to the synthesis of octahydroquinazolinones. Excellent product yields, a fast reaction time, and simple work-up methods are some peculiarities associated with the ultrasonically synthesized catalyst. The recycling study was also investigated and found suitable for up to four reaction cycles.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alex Manicardi ◽  
Enrico Cadoni ◽  
Annemieke Madder

AbstractLigation methodologies featuring bio-orthogonal units and leading to the formation of a stable adduct are the ideal candidates for being applied in a biological context. However, most of the available strategies rely on highly reactive species that require careful handling, or on the activation of pro-reactive functional groups. We here report on a proximity-induced ligation reaction that relies on a stable 2,5-dione, that can be conveniently generated under acidic conditions from a 2,5-dialkylfuran building block, and hydrazine nucleophiles. This bio-orthogonal ligation, which proceeds under physiological conditions, does not require any stimulus or trigger and leads to the formation of a pyridazinium adduct that demonstrates excellent stability under harsh conditions (24 h at 90 °C). The reaction was applied to the formation of PNA-PNA adducts, DNA- and RNA-templated ligations, and for the formation of peptide-peptide adducts in solution. This convenient methodology was further implemented on plastic and glass surfaces to realize self-addressable covalent constructs.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tao Li ◽  
Chuang Feng ◽  
Boon Kar Yap ◽  
Xuhui Zhu ◽  
Biquan Xiong ◽  
...  

AbstractOne of the challenges for high-efficiency single-component-based photoredox catalysts is the low charge transfer and extraction due to the high recombination rate. Here, we demonstrate a strategy to precisely control the charge separation and transport efficiency of the catalytic host by introducing electron or hole extraction interlayers to improve the catalytic efficiency. We use simple and easily available non-conjugated polyelectrolytes (NCPs) (i.e., polyethyleneimine, PEI; poly(allylamine hydrochloride), PAH) to form interlayers, wherein such NCPs consist of the nonconjugated backbone with charge transporting functional groups. Taking CdS as examples, it is shown that although PEI and PAH are insulators and therefore do not have the ability to conduct electricity, they can form good electron or hole transport extraction layers due to the higher charge-transfer kinetics of pendant groups along the backbones, thereby greatly improving the charge transfer capability of CdS. Consequently, the resultant PEI-/PAH-functionalized nanocomposites exhibit significantly enhanced and versatile photoredox catalysis.


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