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22 pages, 10417 KB

Open AccessArticle

Simple One–Pot Synthesis of Hexakis(2-alkoxy-1,5-phenyleneimine) Macrocycles by Precipitation–Driven Cyclization

by Toshihiko Matsumoto

Macromol 2024, 4(1), 1-22; https://doi.org/10.3390/macromol4010001 - 3 Jan 2024

Cited by 1 | Viewed by 2106

Hexakis(2-alkoxy-1,5-phenyleneimine) macrocycles were synthesized using a simple one-pot procedure through precipitation-driven cyclization. The acetal-protected AB–type monomers, 2-alkoxy-5-aminobenzaldehyde diethyl acetals, underwent polycondensation in water or acid-containing tetrahydrofuran. The precipitation–driven cyclization, based on imine dynamic covalent chemistry and π–stacked columnar aggregation, played a decisive role [...] Read more.

Hexakis(2-alkoxy-1,5-phenyleneimine) macrocycles were synthesized using a simple one-pot procedure through precipitation-driven cyclization. The acetal-protected AB–type monomers, 2-alkoxy-5-aminobenzaldehyde diethyl acetals, underwent polycondensation in water or acid-containing tetrahydrofuran. The precipitation–driven cyclization, based on imine dynamic covalent chemistry and π–stacked columnar aggregation, played a decisive role in the one–pot synthesis. The progress of the reaction was analyzed using MALDI–TOF mass spectrometry. The macrocycles with alkoxy chains were soluble in specific organic solvents, such as chloroform, allowing their structures to be analyzed using NMR. The shape-anisotropic, nearly planar, and shape-persistent macrocycles aggregated into columnar assemblies in polymerization solvents, driven by aromatic π-stacking. The octyloxylated macrocycle OcO–Cm6 exhibited an enantiotropic columnar liquid crystal-like mesophase between 165 °C and 197 °C. In the SEM image of (S)-(–)-3,7-dimethyloctyloxylated macrocycle (–)BCO–Cm6, columnar substances with a diameter of 200–300 nm were observed. The polymerization solution for the 2-(2-methoxyethoxy)ethoxy)ethoxylated macrocycle (TEGO–Cm6) gelled, and showed thixotropic properties by forming a hydrogen bond network. Full article

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20 pages, 3772 KB

Open AccessReview

A Review of Fifteen Years Developing Computational Tools to Study Protein Aggregation

by Carlos Pintado-Grima, Oriol Bárcenas, Andrea Bartolomé-Nafría, Marc Fornt-Suñé, Valentín Iglesias, Javier Garcia-Pardo and Salvador Ventura

Biophysica 2023, 3(1), 1-20; https://doi.org/10.3390/biophysica3010001 - 18 Jan 2023

Cited by 7 | Viewed by 6589

Abstract

The presence of insoluble protein deposits in tissues and organs is a hallmark of many human pathologies. In addition, the formation of protein aggregates is considered one of the main bottlenecks to producing protein-based therapeutics. Thus, there is a high interest in rationalizing [...] Read more.

The presence of insoluble protein deposits in tissues and organs is a hallmark of many human pathologies. In addition, the formation of protein aggregates is considered one of the main bottlenecks to producing protein-based therapeutics. Thus, there is a high interest in rationalizing and predicting protein aggregation. For almost two decades, our laboratory has been working to provide solutions for these needs. We have traditionally combined the core tenets of both bioinformatics and wet lab biophysics to develop algorithms and databases to study protein aggregation and its functional implications. Here, we review the computational toolbox developed by our lab, including programs for identifying sequential or structural aggregation-prone regions at the individual protein and proteome levels, engineering protein solubility, finding and evaluating prion-like domains, studying disorder-to-order protein transitions, or categorizing non-conventional amyloid regions of polar nature, among others. In perspective, the succession of the tools we describe illustrates how our understanding of the protein aggregation phenomenon has evolved over the last fifteen years. Full article

(This article belongs to the Special Issue State-of-the-Art Biophysics in Spain)

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7 pages, 1152 KB

Open AccessCommunication

Recovery of Lac Resin from the Aqueous Effluent of Shellac Industry

by Gaurav Badhani, Shruti Yadav, Elen Reji and Subbarayappa Adimurthy

Sustain. Chem. 2023, 4(1), 1-7; https://doi.org/10.3390/suschem4010001 - 21 Dec 2022

Cited by 6 | Viewed by 4749

Abstract

Shellac and aleuritic acid manufacturing industries generate a lot of alkaline aqueous effluent during the process of manufacture of shellac and aleuritic acid from the seedlac/sticklac. The generated effluent contains lac resin, lac wax, lac dye and other water-soluble organic acids. Shellac industries [...] Read more.

Shellac and aleuritic acid manufacturing industries generate a lot of alkaline aqueous effluent during the process of manufacture of shellac and aleuritic acid from the seedlac/sticklac. The generated effluent contains lac resin, lac wax, lac dye and other water-soluble organic acids. Shellac industries in India face problems with the disposal of aqueous effluent due to the presence of considerable amounts of natural organic molecules and the dark colour solution. To address these problems, we have developed a novel method for the selective recovery of the lac resin from the alkaline aqueous effluent of shellac manufacturing industry. The recovered lac resin has been characterized by ¹³C-NMR, FT-IR and melting point and the data were compared with standard industrial-grade resin. The recovered lac resin was evaluated by the lac manufacturing industry for commercial applications. Full article

(This article belongs to the Special Issue Alternative Solvents for Green Chemistry)

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31 pages, 5585 KB

Open AccessReview

Cyclodextrins: Structural, Chemical, and Physical Properties, and Applications

by Benjamin Gabriel Poulson, Qana A. Alsulami, Abeer Sharfalddin, Emam. F. El Agammy, Fouzi Mouffouk, Abdul-Hamid Emwas, Lukasz Jaremko and Mariusz Jaremko

Polysaccharides 2022, 3(1), 1-31; https://doi.org/10.3390/polysaccharides3010001 - 28 Dec 2021

Cited by 238 | Viewed by 34002

Abstract

Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability [...] Read more.

Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered. Full article

(This article belongs to the Collection Current Opinion in Polysaccharides)

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10 pages, 1039 KB

Open AccessArticle

Water Removal from LOHC Systems

by Karsten Müller, Rabya Aslam, André Fikrt, Christoph Krieger and Wolfgang Arlt

Hydrogen 2020, 1(1), 1-10; https://doi.org/10.3390/hydrogen1010001 - 10 Oct 2020

Cited by 1 | Viewed by 4722

Abstract

Liquid organic hydrogen carriers (LOHC) store hydrogen by reversible hydrogenation of a carrier material. Water can enter the system via wet hydrogen coming from electrolysis as well as via moisture on the catalyst. Removing this water is important for reliable operation of the [...] Read more.

Liquid organic hydrogen carriers (LOHC) store hydrogen by reversible hydrogenation of a carrier material. Water can enter the system via wet hydrogen coming from electrolysis as well as via moisture on the catalyst. Removing this water is important for reliable operation of the LOHC system. Different approaches for doing this have been evaluated on three stages of the process. Drying of the hydrogen, before entering the LOHC system itself, is preferable. A membrane drying process turns out to be the most efficient way. If the water content in the LOHC system is still so high that liquid–liquid demixing occurs, it is crucial for water removal to enhance the slow settling. Introduction of an appropriate packing can help to separate the two phases as long as the volume flow is not too high. Further drying below the rather low solubility limit is challenging. Introduction of zeolites into the system is a possible option. Water adsorbs on the surface of the zeolite and moisture content is therefore decreased. Full article

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11 pages, 175 KB

Open AccessArticle

Levels of Sulfur as an Essential Nutrient Element in the Soil-Crop-Food System in Austria

by Manfred Sager

Agriculture 2012, 2(1), 1-11; https://doi.org/10.3390/agriculture2010001 - 12 Jan 2012

Cited by 17 | Viewed by 8587

Abstract

Total sulfur data of various agricultural and food items from the lab of the author, have been compiled to develop an understanding of sulfur levels and ecological cycling in Austria. As sulfur level is not an included factor among the quality criteria of [...] Read more.

Total sulfur data of various agricultural and food items from the lab of the author, have been compiled to develop an understanding of sulfur levels and ecological cycling in Austria. As sulfur level is not an included factor among the quality criteria of soil and fertilizer composition, the database is rather small. Problems in analytical determinations of total sulfur, in particular digestions, are outlined. As a protein component, sulfur is enriched in matrices of animal origin, in particular in egg white. There is substantial excretion from animals and man via urine. Organic fertilizers (manures, composts) might contribute significantly to the sulfur budget of soils, which is important for organic farming of crops with high sulfur needs. For soils, drainage is a main route of loss of soluble sulfate, thus pot experiments may yield unrealistic sulfur budgets. Full article

(This article belongs to the Special Issue Soil Biology and Its Importance in Soil Fertility)

15 pages, 291 KB

Open AccessArticle

NMR-Metabolic Methodology in the Study of GM Foods

by Anatoly P. Sobolev, Donatella Capitani, Donato Giannino, Chiara Nicolodi, Giulio Testone, Flavio Santoro, Giovanna Frugis, Maria A. Iannelli, Autar K. Mattoo, Elvino Brosio, Raffaella Gianferri, Irene D’Amico and Luisa Mannina

Nutrients 2010, 2(1), 1-15; https://doi.org/10.3390/nu2010001 - 13 Jan 2010

Cited by 22 | Viewed by 13604

Abstract

The¹H-NMR methodology used in the study of genetically modified (GM) foods is discussed. Transgenic lettuce (Lactuca sativa cv \"Luxor\") over-expressing the Arabidopsis KNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars) present in [...] Read more.

The¹H-NMR methodology used in the study of genetically modified (GM) foods is discussed. Transgenic lettuce (Lactuca sativa cv \"Luxor\") over-expressing the Arabidopsis KNAT1 gene is presented as a case study. Twenty-two water-soluble metabolites (amino acids, organic acids, sugars) present in leaves of conventional and GM lettuce were monitored by NMR and quantified at two developmental stages. The NMR spectra did not reveal any difference in metabolite composition between the GM lettuce and the wild type counterpart. Statistical analyses of metabolite variables highlighted metabolism variation as a function of leaf development as well as the transgene. A main effect of the transgene was in altering sugar metabolism. Full article

(This article belongs to the Special Issue Foodomics 2009)

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23 pages, 401 KB

Open AccessArticle

Iron Complexation to Oxygen Rich Marine Natural Products: A Computational Study

by Thomas J. Manning, Jimmy Williams, Joey Jarrard and Teresa Gorman

Mar. Drugs 2010, 8(1), 1-23; https://doi.org/10.3390/md8010001 - 4 Jan 2010

Cited by 5 | Viewed by 12442

Abstract

The natural products kahalalide F, halichondrin B, and discodermolide are relatively large structures that were originally harvested from marine organisms. They are oxygen rich structures that, to varying degrees, should have the ability to bind iron (II or III) by Fe-O and/or Fe-N [...] Read more.

The natural products kahalalide F, halichondrin B, and discodermolide are relatively large structures that were originally harvested from marine organisms. They are oxygen rich structures that, to varying degrees, should have the ability to bind iron (II or III) by Fe-O and/or Fe-N bonds. In this semi empirical study, the binding of these natural products to iron (II) is studied and the aqueous stability factor (ASF) is used to determine which bonding configuration is most stable. The energy, the complex charge (+1), the average Fe-O (or Fe-N) bond distances and the dipole moments are used to calculate the ASF. The ASF provides insight to which complex will be the most stable and water soluble, important for a medicinal application. The ability of a molecule with a more than six oxygen and/or nitrogen atoms to bind iron (hexavalent, octahedral) by shifting which six atoms (O/N) are bound to the iron qualifies it as a polarity adaptive molecule. Full article

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