Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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34 pages, 725 KiB  
Article
Chemical Compositions and Essential Fatty Acid Analysis of Selected Vegetable Oils and Fats
by Pawan Kumar Ojha, Darbin Kumar Poudel, Anil Rokaya, Salina Maharjan, Sunita Timsina, Ambika Poudel, Rakesh Satyal, Prabodh Satyal and William N. Setzer
Compounds 2024, 4(1), 37-70; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds4010003 - 17 Jan 2024
Viewed by 2471
Abstract
The fatty acid (FA) compositions of thirty-nine vegetable oils and fats, including nangai nut, pili nut, shea butter, tamanu oil, baobab, sea buckthorn berry, Brazil nut, grape seed, black seed, evening primrose, passion fruit, milk thistle, sunflower, pumpkin seed, sesame, soybean, flax seed, [...] Read more.
The fatty acid (FA) compositions of thirty-nine vegetable oils and fats, including nangai nut, pili nut, shea butter, tamanu oil, baobab, sea buckthorn berry, Brazil nut, grape seed, black seed, evening primrose, passion fruit, milk thistle, sunflower, pumpkin seed, sesame, soybean, flax seed, kukui, red raspberry seed, walnut, chia seed, hemp seed, rosehip, almond, avocado, carrot seed, moringa, apricot kernel, camellia seed, macadamia, olive, marula, argan, castor, jojoba, pomegranate seed, medium-chain triglyceride (MCT) coconut, roasted coconut, canola, and mustard oil, were analyzed using gas chromatography–mass spectrometry (GC-MS). Vegetable oils and fats have different profiles in terms of their fatty acid composition, and their major constituents vary significantly. However, we categorized them into different classes based on the percentages of different fatty acids they contain. The saturated fatty acids, such as palmitic acid and stearic acid, and the unsaturated fatty acids, including oleic acid, linoleic acid, and linolenic acid, are the main categories. Among them, roasted coconut oil contained the greatest amount of saturated fatty acids followed by nangai nut (45.61%). Passion fruit oil contained the largest amount of linoleic acid (66.23%), while chia seed oil had the highest content of linolenic acid (58.25%). Oleic acid was exclusively present in camellia seed oil, constituting 78.57% of its composition. Notably, mustard oil had a significant presence of erucic acid (54.32%), while pomegranate seed oil exclusively contained punicic acid (74.77%). Jojoba oil primarily consisted of (Z)-11-eicosenoic acid (29.55%) and (Z)-docos-13-en-1-ol (27.96%). The major constituent in castor oil was ricinoleic acid (89.89%). Compared with other vegetable oils and fats, pili nut oil contained a significant amount of (E)-FA (20.62%), followed by sea buckthorn berry oil with a content of 9.60%. FA compositions from sources may be problematic in the human diet due to no labeling or the absence of essential components. Therefore, consumers must cast an eye over some essential components consumed in their dietary intake. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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20 pages, 4000 KiB  
Article
Hydroxyhydroquinone and Quassinoids as Promising Compounds with Hypoglycemic Activity through Redox Balance
by Paulo R. dos Santos, Sidinéia Danetti, A. Joseph Rastegar, Wellington V. de Souza, Rafaele Frassini, Fernando J. Scariot, Sidnei Moura and Mariana Roesch-Ely
Compounds 2024, 4(1), 17-36; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds4010002 - 03 Jan 2024
Viewed by 714
Abstract
In the present study, an insulin-resistant cell model (human hepatocellular carcinoma cell line: HepG2) was chosen to investigate the efficacy of two compound classes and their common molecular motif for glycemic control and insulin sensitization. The two compounds’ classes were flavonoid extracts from [...] Read more.
In the present study, an insulin-resistant cell model (human hepatocellular carcinoma cell line: HepG2) was chosen to investigate the efficacy of two compound classes and their common molecular motif for glycemic control and insulin sensitization. The two compounds’ classes were flavonoid extracts from Rourea cuspidata and quassinoid extracts from Picrasma crenata. The flavonoid-like hydroxyhydroquinone (HHQ) was synthesized. HepG2 cells were tested in a high-glucose environment (HepG2/IRM) by monitoring ROS activity, the concentration of adenosine triphosphate (ATP), and the measurement of mitochondrial membrane potential (MMP). The expression of forkhead box O1 (FOXO1) protein, which mediates gluconeogenesis and insulin resistance, was also investigated using indirect immunocytochemistry and Western blot techniques. A significant increase in glucose uptake and well-regulated ATP concentrations were observed in the treated cells. The downregulation of FOXO1 expression was seen in cells treated with HHQ and quassinoids in comparison to cells treated with flavonoids. This study provides a pharmacological basis for the application of HHQ, quassinoids from P. crenata, and flavonoids from R. cuspidata in the treatment of metabolic diseases such as type 2 diabetes mellitus. Full article
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9 pages, 2757 KiB  
Communication
Identifying the Structural Components Responsible for the Antiproliferative Properties of Hydroxychavicol
by Joshua Jackson, Gerome M. Romero, Diana Hawkins, Richard G. Cornwall and Georgi L. Lukov
Compounds 2023, 3(4), 552-560; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3040039 - 25 Oct 2023
Cited by 1 | Viewed by 1455
Abstract
Betel leaves are widely used as herbal medicine in Asia due to their antimicrobial properties. These properties have been attributed to the phenolic compound eugenol and its derivative, hydroxychavicol. Hydroxychavicol has also been shown to inhibit cancer cell proliferation. The main objective of [...] Read more.
Betel leaves are widely used as herbal medicine in Asia due to their antimicrobial properties. These properties have been attributed to the phenolic compound eugenol and its derivative, hydroxychavicol. Hydroxychavicol has also been shown to inhibit cancer cell proliferation. The main objective of this study was to investigate which structural components of hydroxychavicol are responsible for the antiproliferative property of this compound. Jurkat-E6 cells (JE6) were treated with increasing concentrations (5, 15, and 45 µM) of hydroxychavicol and structural variants of it for 48 h. The results of this study demonstrate that the catechol structure in hydroxychavicol is the structural component that exhibits the highest antiproliferative effect. More specifically, the data show that the six-carbon ring must be aromatic with the two hydroxyl groups attached in an ortho position. Furthermore, this study establishes that the oxygen in the hydroxyl groups has a vital role in the antiproliferative properties of catechol and hydroxychavicol. Full article
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17 pages, 4319 KiB  
Article
Thiazolidine-Based Fluorescent Chiral Ionic Liquids for Trace Copper(II) Ion Sensing
by Cassiana H. Griebeler, Mariana F. Bach, Henrique C. Silva, Jr., Fabiano S. Rodembusch, Felipe L. Coelho and Paulo H. Schneider
Compounds 2023, 3(3), 430-446; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3030032 - 11 Aug 2023
Cited by 1 | Viewed by 1134
Abstract
This study presents a comprehensive analysis of the synthesis and photophysical properties of thiazolidine-functionalized chiral ionic liquids (CILs) derived from L-cysteine. The synthesis involves a four-step route, encompassing N-protection, coupling reactions with bromoalcohols, and ionic liquid formation. The optical properties of the [...] Read more.
This study presents a comprehensive analysis of the synthesis and photophysical properties of thiazolidine-functionalized chiral ionic liquids (CILs) derived from L-cysteine. The synthesis involves a four-step route, encompassing N-protection, coupling reactions with bromoalcohols, and ionic liquid formation. The optical properties of the compounds were evaluated using UV–Vis absorption and fluorescence emission spectroscopies, revealing distinct behavior for different heterocycles and counter-ions. Notably, the investigation reveals that thiazolidine-based CILs exhibit unconventional intrinsic luminescence characteristics. Building upon these photophysical properties, an interaction study was conducted between copper (II) and the CILs. The findings exhibit a robust linear relationship between the optical response and the concentration of the metal ion. Through the calculation of the Stern–Volmer quenching constant, it was determined that the 1:1 binding model is applicable. This research underscores the potential of UV–Vis absorption spectroscopy as a highly sensitive method for detecting metal ions. By elucidating the synthesis, photophysical behavior, and metal ion interaction of thiazolidine-based CILs, this study contributes valuable insights into the field of functionalized ionic liquids and their potential applications in various areas. Full article
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17 pages, 4118 KiB  
Article
Interplay between Fe(II) and Fe(III) and Its Impact on Thermoelectric Properties of Iron-Substituted Colusites Cu26−xFexV2Sn6S32
by Alexey O. Polevik, Alexey V. Sobolev, Iana S. Glazkova, Igor A. Presniakov, Valeriy Yu. Verchenko, Joosep Link, Raivo Stern and Andrei V. Shevelkov
Compounds 2023, 3(2), 348-364; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3020027 - 15 May 2023
Cited by 2 | Viewed by 1503
Abstract
Following the trend of finding better thermoelectric materials among synthetic analogs of copper–chalcogenide minerals, we have synthesized iron-bearing colusites of a general formula Cu26−xFexV2Sn6S32. They crystallize in the cubic space group P-43n [...] Read more.
Following the trend of finding better thermoelectric materials among synthetic analogs of copper–chalcogenide minerals, we have synthesized iron-bearing colusites of a general formula Cu26−xFexV2Sn6S32. They crystallize in the cubic space group P-43n with the unit cell parameter increasing linearly with the iron content. At a low iron concentration, the crystal structure features disorder manifested by an anti-site effect and a shift of a part of the tin atoms from their ideal positions, which is absent for higher iron contents. The magnetization and 57Fe/119Sn Mössbauer studies showed that, for x = 1, iron is present as Fe3+, whereas for x > 1, Fe2+ and Fe3+ coexist. Additionally, weak antiferromagnetic interactions between iron atoms and fast on the 57Fe Mössbauer time scale (107–109 s−1) electron transfer between adjacent Fe2+ and Fe3+ centers were revealed. Thermoelectric studies showed that iron-bearing colusites are p-type semiconductors with low thermal conductivity stemming from their complex crystal structure and structural disorder. The highest ZT of 0.78 at 700 K was found for the x = 1 iron content, where iron is present as Fe3+ only. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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5 pages, 2537 KiB  
Communication
The Effect of Strain on the Aromatic Character of Infinitene
by Maurizio D’Auria
Compounds 2023, 3(2), 336-340; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3020025 - 18 Apr 2023
Cited by 1 | Viewed by 972
Abstract
Infinitene was synthesized in a previous study in 2021, and the molecule showed high strain energy. It was not clear how the strain affected the aromatic character of the molecule. To discuss this problem, the aromatic properties of dodecacene, [12]circulene, and infinitene have [...] Read more.
Infinitene was synthesized in a previous study in 2021, and the molecule showed high strain energy. It was not clear how the strain affected the aromatic character of the molecule. To discuss this problem, the aromatic properties of dodecacene, [12]circulene, and infinitene have been studied. The structures of these compounds have been optimized at the DFT/B3LYP/6-311G + (d,p) level of theory, and the energy of the π orbitals has been used to determine the D’ index of the aromaticity. D′ for dodecacene, [12]circulene, and infinitene were 1.45, 1.45, and 1.50, respectively, showing that infinitene is an aromatic compound but with a lower aromatic character, which is in agreement with the observed strain. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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9 pages, 3223 KiB  
Communication
Predicting the Average Composition of an AlFeNiTiVZr-Cr Alloy with Machine Learning and X-ray Spectroscopy
by Tarik Sadat
Compounds 2023, 3(1), 224-232; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3010018 - 03 Mar 2023
Cited by 4 | Viewed by 1335
Abstract
A multi-principal element alloy (MPEA) is a type of metallic alloy that is composed of multiple metallic elements, with each element making up a significant portion of the alloy. In this study, the initial atomic percentage of elements in an (AlFeNiTiVZr)1-xCrx MPEA alloy [...] Read more.
A multi-principal element alloy (MPEA) is a type of metallic alloy that is composed of multiple metallic elements, with each element making up a significant portion of the alloy. In this study, the initial atomic percentage of elements in an (AlFeNiTiVZr)1-xCrx MPEA alloy as a function of the position on the surface was investigated using machine learning algorithms. Given the absence of a linear relationship between the atomic percentage of elements and their location on the surface, it is not possible to discern any clear association from the dataset. To overcome this non-linear relationship, the prediction of the atomic percentage of elements was accomplished using both decision tree (DT) and random forest (RF) regression models. The models were compared, and the results were found to be consistent with the experimental findings (a coefficient of determination R2 of 0.98 is obtained with the DT algorithm and 0.99 with the RF one). This research demonstrates the potential of machine learning algorithms in the analysis of wavelength-dispersive X-ray spectroscopy (WDS) datasets. Full article
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16 pages, 8359 KiB  
Article
Fluorinated Merophosphinine and Phosphinine Dyes: Synthesis and Evaluation of UV-Visible Light Absorption Properties
by Shigeyuki Yamada, Yusuke Takahashi and Tsutomu Konno
Compounds 2023, 3(1), 153-168; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3010013 - 02 Feb 2023
Cited by 2 | Viewed by 1717
Abstract
Merophosphinine and phosphinine dyes were reported as phosphorus atom equivalents of merocyanine and cyanine dyes in the 1960s. Although these dyes are excellent sensitizers for enhancing photographic performance, their development has been considerably retarded because of difficulties in the synthetic process. Previously, while [...] Read more.
Merophosphinine and phosphinine dyes were reported as phosphorus atom equivalents of merocyanine and cyanine dyes in the 1960s. Although these dyes are excellent sensitizers for enhancing photographic performance, their development has been considerably retarded because of difficulties in the synthetic process. Previously, while investigating the reactivity of fluoroalkenes with various nucleophiles, we developed fluorinated merophosphinine and phosphinine scaffolds in a single reaction step; however, we did not investigate their ultraviolet-visible (UV-vis) light absorption properties further. Therefore, in this study, we synthesized fluorinated merophosphinines and phosphinine derivatives using triphenylphosphonium ylides with various R substituents [R = H, C6H5, 4-MeOC6H4, 4-PhC6H4, or C6F5] and octafluorocyclopentene to study their absorption characteristics. Thermogravimetric analyses (TGA) indicated that several synthesized derivatives were thermally stable at temperatures above 241 °C. Additionally, when studied in various solvents, the fluorinated merophosphinine and phosphinine dyes exhibited well-defined maximum absorption wavelengths (λabs) in the 364–375 and 420–474 nm ranges, respectively. Thus, fluorinated merophosphinine and phosphinine derivatives may serve as promising thermally stable functional dyes for future technical applications. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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13 pages, 2038 KiB  
Article
Reduction Potential Predictions for Thirty-Seven 1,4-di-N-Oxide Quinoxaline-2-Carboxamide Derivatives with Anti-Tuberculosis Activity
by Faranak Pooladian, Philip W. Crawford, Jonathan M. Kessler, Garrett R. Casey and Christina M. Ragain
Compounds 2023, 3(1), 83-95; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3010007 - 13 Jan 2023
Cited by 3 | Viewed by 1227
Abstract
The ability for density functional theory with the B3LYP functional with the lanl2dz basis set to predict the 1st (Wave 1) and 2nd (Wave 2) reductions of the diazine ring in a series of thirty-seven (37) 1,4-di-N-oxide quinoxaline-2-carboxamide derivatives in dimethylformamide was examined. [...] Read more.
The ability for density functional theory with the B3LYP functional with the lanl2dz basis set to predict the 1st (Wave 1) and 2nd (Wave 2) reductions of the diazine ring in a series of thirty-seven (37) 1,4-di-N-oxide quinoxaline-2-carboxamide derivatives in dimethylformamide was examined. The B3LYP/lanl2dz method had a strong correlation and low correlation to the experimental potentials for Wave 1 and Wave 2, respectively. There are nine identifiable analogs based on similarities of structure. The predicted reduction potentials for the derivatives of each analog generally fit the modified Hammett equation. The B3LYP/lanl2dz method is shown to be useful in accurately predicting the Wave 1 potentials for quinoxaline-di-N-oxide derivatives. For derivatives with assessable anti-tuberculosis activity, the predicted Wave 1 potentials have a similar correlation with the bioactivity when compared to the experimental wave 1 potentials. Full article
(This article belongs to the Special Issue Organic Compounds with Biological Activity)
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10 pages, 1114 KiB  
Communication
Facile Synthesis of Pyrrolyl-Containing Semisquaraines in Water as Precursors for Non-Symmetric Squaraines
by Daniel D. Ta, Jeanne M. Favret and Sergei V. Dzyuba
Compounds 2023, 3(1), 17-26; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds3010002 - 28 Dec 2022
Cited by 1 | Viewed by 1600
Abstract
One-step reactions between squaric acid and pyrroles, such as 3-ethyl-2,4-dimethyl-pyrrole and 1,2,5-trimethylpyrrole, in water provide the corresponding pyrrol-2-yl- and pyrrol-3-yl-containing semisquaraines in high yields. These semisquaraines serve as useful precursors for the synthesis of various non-symmetric pyrrole-containing squaraine dyes. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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13 pages, 1874 KiB  
Article
Possible Role of Vesicles on Metallocatalytic Reduction Reaction of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran
by Toshinori Shimanouchi, Yuki Takahashi, Keita Hayashi, Kazuma Yasuhara and Yukitaka Kimura
Compounds 2022, 2(4), 321-333; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2040027 - 03 Nov 2022
Cited by 3 | Viewed by 1298
Abstract
A reduction reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran (2,5-DMF) has been previously performed in an organic solvent under high-temperature conditions. For the relaxation of such reaction conditions, conventional palladium on carbon (Pd/C) was combined with vesicles composed of phospholipids or surfactants. Pd/C combined with [...] Read more.
A reduction reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran (2,5-DMF) has been previously performed in an organic solvent under high-temperature conditions. For the relaxation of such reaction conditions, conventional palladium on carbon (Pd/C) was combined with vesicles composed of phospholipids or surfactants. Pd/C combined with 1,2-dioleoyl-sn-glycero-3-phosphocholine indicated a yield (25%) at 60 °C compared with Pd/C (17%). Vesicles at the liquid crystalline phase were advantageous for the reduction reaction of HMF. The yield of 2,5-DMF catalyzed by Pd/C combined with the vesicles depended on the lipid composition of the vesicles. It was clarified that the yield of 2,5-DMF could be controlled by the hydration property of the vesicles. Compared with conventional 2,5-DMF synthesis in an organic solvent, the use of vesicles made it possible to reduce the burden of using organic solvents in high-temperature conditions, although limitedly. Full article
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8 pages, 2124 KiB  
Article
Influence of Secondary Interactions on Structural Diversity between a Pair of Halogen-Bonded Co-Crystals Containing Isosteric Donors
by Herman R. Krueger, Jr., Nicole M. Shapiro, Eric Bosch, Daniel K. Unruh and Ryan H. Groeneman
Compounds 2022, 2(4), 285-292; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2040023 - 28 Oct 2022
Cited by 2 | Viewed by 1176
Abstract
The formation of a pair of co-crystals based upon isosteric halogen-bond donors, namely 1,4-diiodoperchlorobenzene and iodoperchlorobenzene, along with the acceptor 4,4-bipyridine is reported. As expected, the components in each co-crystal engage in halogen bonding interactions resulting in a one-dimensional chain-like structure. In particular, [...] Read more.
The formation of a pair of co-crystals based upon isosteric halogen-bond donors, namely 1,4-diiodoperchlorobenzene and iodoperchlorobenzene, along with the acceptor 4,4-bipyridine is reported. As expected, the components in each co-crystal engage in halogen bonding interactions resulting in a one-dimensional chain-like structure. In particular, the co-crystal containing 1,4-diiodoperchlorobenzene is primarily held together by I···N halogen bonds while the solid based upon iodoperchlorobenzene forms both I···N and Cl···N interactions. Structural diversity is achieved between these co-crystals based upon the type of secondary interactions involving the chlorine atoms on each halogen-bond donor even though they are isosteric in nature. Full article
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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12 pages, 4320 KiB  
Article
Effect of KCl Addition on First Hydrogenation Kinetics of TiFe
by Joydev Manna and Jacques Huot
Compounds 2022, 2(4), 240-251; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2040020 - 06 Oct 2022
Cited by 2 | Viewed by 1513
Abstract
In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe’s surface. As-synthesized TiFe does not absorb hydrogen. However, after ball [...] Read more.
In this paper, the effect of the addition of potassium chloride (KCl) by ball milling on the first hydrogenation kinetics of TiFe is reported. After milling, KCl was uniformly distributed on the TiFe’s surface. As-synthesized TiFe does not absorb hydrogen. However, after ball milling with KCl, it absorbed 1.5 wt.% of hydrogen on the first hydrogenation without any thermal treatment. The storage capacity of TiFe with KCl addition is higher than that of the ball milled pure TiFe. The effects of the amount of KCl additive in TiFe and ball milling time on first hydrogenation kinetics are reported. It is noted that, with an increase in KCl amount and ball milling time, hydrogenation kinetics are improved. However, hydrogen storage capacity decreased for both cases. Full article
(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)
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9 pages, 1014 KiB  
Communication
Synthesis of Thiazolidinedione Compound Library
by Fehmi Damkaci, Adam A. Szymaniak, Jason P. Biasini and Ryan Cotroneo
Compounds 2022, 2(3), 182-190; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2030013 - 05 Jul 2022
Cited by 2 | Viewed by 2849
Abstract
Thiazolidinediones (TZDs), also known as Glitazones, have anti-diabetic, anti-inflammatory and anti-cancer properties. A simple, efficient and cost-effective synthesis of a thiazolidinedione compound library was developed. The synthesis is facilitated by microwave irradiation in three of the four steps followed by reduction under pressurized [...] Read more.
Thiazolidinediones (TZDs), also known as Glitazones, have anti-diabetic, anti-inflammatory and anti-cancer properties. A simple, efficient and cost-effective synthesis of a thiazolidinedione compound library was developed. The synthesis is facilitated by microwave irradiation in three of the four steps followed by reduction under pressurized hydrogen gas using palladium hydroxide. All reactions, except one, were completed within an hour and provided desired products in moderate to good yields after a simple work-up. Full article
(This article belongs to the Special Issue Feature Papers in Compounds)
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10 pages, 1414 KiB  
Article
A Photoswitchable Chalcone-Carbohydrate Conjugate Obtained by CuAAC Click Reaction
by Micael Paulino, Maria Manuela A. Pereira and Nuno Basílio
Compounds 2022, 2(2), 111-120; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2020008 - 29 Mar 2022
Cited by 2 | Viewed by 2564
Abstract
Flavylium/Chalcone-based molecular switches comprise features such as pH-gated photochromism and fluorescence properties that make them attractive for many applications, ranging from stimuli-responsive materials to photopharmacology. However, in contrast to other common photoswitches, the application of flavylium compounds in these areas remains largely unexplored. [...] Read more.
Flavylium/Chalcone-based molecular switches comprise features such as pH-gated photochromism and fluorescence properties that make them attractive for many applications, ranging from stimuli-responsive materials to photopharmacology. However, in contrast to other common photoswitches, the application of flavylium compounds in these areas remains largely unexplored. Among other possible reasons, this may be due to the lack of general strategies to attach these molecules to substrates such as polymers, nanoparticles, biomolecules, or surfaces. In this work, we have shown that a copper (I) catalyzed azide-alkyne cycloaddition (CuAAC) can be employed to obtain a chalcone conjugate. We used an isosorbide carbohydrate to demonstrate this strategy and investigated the photochemical properties of the chalcone-isosorbide conjugate. The obtained results show that the photochemical properties of this new compound are similar to other equivalent flavylium/chalcone photoswitches, confirming the feasibility of the conjugation strategy. Full article
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31 pages, 7242 KiB  
Review
The Nitrogen Bond, or the Nitrogen-Centered Pnictogen Bond: The Covalently Bound Nitrogen Atom in Molecular Entities and Crystals as a Pnictogen Bond Donor
by Pradeep R. Varadwaj, Arpita Varadwaj, Helder M. Marques and Koichi Yamashita
Compounds 2022, 2(1), 80-110; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds2010007 - 15 Mar 2022
Cited by 20 | Viewed by 5014
Abstract
The nitrogen bond in chemical systems occurs when there is evidence of a net attractive interaction between the electrophilic region associated with a covalently or coordinately bound nitrogen atom in a molecular entity and a nucleophile in another, or the same molecular entity. [...] Read more.
The nitrogen bond in chemical systems occurs when there is evidence of a net attractive interaction between the electrophilic region associated with a covalently or coordinately bound nitrogen atom in a molecular entity and a nucleophile in another, or the same molecular entity. It is the first member of the family of pnictogen bonds formed by the first atom of the pnictogen family, Group 15, of the periodic table, and is an inter- or intra-molecular non-covalent interaction. In this featured review, we present several illustrative crystal structures deposited in the Cambridge Structure Database (CSD) and the Inorganic Crystal Structure Databases (ICSD) to demonstrate that imide nitrogen is not the only instance where nitrogen can act as an electrophilic agent. Analysis of a set of carefully chosen illustrative crystal systems shows that a covalently bound nitrogen atom in a variety of molecular entities features a σ-hole or even a π-hole, and these have the ability to sustain attractive engagements with negative sites to form inter- and/or intramolecular interactions that drive, or assist, the formation of a crystalline phase. Full article
(This article belongs to the Special Issue Feature Papers in Compounds)
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10 pages, 1490 KiB  
Communication
Glucosylimidazolium Hydroxide: A Bench-Stable Carbohydrate Based Building Block
by Johannes Schnegas and Stefan Jopp
Compounds 2021, 1(3), 154-163; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1030014 - 07 Dec 2021
Cited by 3 | Viewed by 2903
Abstract
Hygroscopic effects in ionic liquids and salts in general, and how to suppress said hygroscopy, often needs to be considered during the everyday work routine. Chemicals that decompose, undergo hydrolysis or in any way change their composition when exposed to air are generally [...] Read more.
Hygroscopic effects in ionic liquids and salts in general, and how to suppress said hygroscopy, often needs to be considered during the everyday work routine. Chemicals that decompose, undergo hydrolysis or in any way change their composition when exposed to air are generally not considered to be bench-stable. In this study, we synthesized a low-hygroscopic, bench-stable carbohydrate-based hydroxide salt. This new product was synthesized in an optimized three-step procedure with 91% overall yield. Its worth as a building block was proven through the reaction with different natural acids, leading to new carbohydrate-based ionic liquids (CHILs) in the process. Full article
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9 pages, 541 KiB  
Article
Synthesis of Optically Active Bicyclic Derivatives of Nitroimidazoles
by Justyna Żwawiak and Lucjusz Zaprutko
Compounds 2021, 1(3), 145-153; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1030013 - 02 Dec 2021
Cited by 2 | Viewed by 2464
Abstract
Nitroimidazoles are characterized by a wide range of biological activity and many of them are used as therapeutics. Moreover, some bicyclic nitroimidazooxazoles show considerable potency against Mycobacterium tuberculosis. Some authors noticed that in the case of chiral derivatives of nitroimidazodihydrooxazoles, the (R [...] Read more.
Nitroimidazoles are characterized by a wide range of biological activity and many of them are used as therapeutics. Moreover, some bicyclic nitroimidazooxazoles show considerable potency against Mycobacterium tuberculosis. Some authors noticed that in the case of chiral derivatives of nitroimidazodihydrooxazoles, the (R) form shows a greater tuberculostatic activity than the (S) enantiomer. This work describes the procurement of new 12 enantiomeric bicyclic derivatives of nitroimidazole. Full article
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11 pages, 1577 KiB  
Article
Volatile Organic Compounds from Orchis Species Found in Basilicata (Southern Italy)
by Marisabel Mecca, Rocco Racioppi, Vito A. Romano, Licia Viggiani, Richard Lorenz and Maurizio D’Auria
Compounds 2021, 1(2), 83-93; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1020008 - 02 Sep 2021
Cited by 10 | Viewed by 3367
Abstract
This study is part of a project devoted to determining the scent of all the orchid species present in Basilicata. All the analyses were performed by using the solid-phase microextraction technique coupled with gas chromatography-mass spectrometry. The scent of eight species belonging to [...] Read more.
This study is part of a project devoted to determining the scent of all the orchid species present in Basilicata. All the analyses were performed by using the solid-phase microextraction technique coupled with gas chromatography-mass spectrometry. The scent of eight species belonging to the Orchis genus was investigated. In the case of O. anthropophora, caryophyllene, tetradecanal and hexadecanal were the main components of the aroma; in O. purpurea, 3,5-dimethoxytoluene and elemicin were found; in O. italica, caryophyllene and 4-(3-hydroxy-2-methoxyphenyl)butan-2-one were found; in O. pauciflora, linalool and 1,4-dimethoxybenzene were found; in O. mascula, linalool was found; in O. quadripunctata, penta- and heptadecane were found; in O. provincialis, β-farnesene and farnesal were found; and in O. pallens, curcumene was the main product. Full article
(This article belongs to the Special Issue Feature Papers in Compounds)
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17 pages, 15674 KiB  
Article
Convenient Access to Functionalized Non-Symmetrical Atropisomeric 4,4′-Bipyridines
by Emmanuel Aubert, Emmanuel Wenger, Paola Peluso and Victor Mamane
Compounds 2021, 1(2), 58-74; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1020006 - 01 Jul 2021
Cited by 6 | Viewed by 2992
Abstract
Non-symmetrical chiral 4,4′-bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4′-bipyridines were prepared and further functionalized by using cross-coupling reactions. [...] Read more.
Non-symmetrical chiral 4,4′-bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4′-bipyridines were prepared and further functionalized by using cross-coupling reactions. The desymmetrization step is based on the N-oxidation of one of the two pyridine rings of the 4,4′-bipyridine skeleton. The main advantage of this methodology is the possible post-functionalization of the pyridine N-oxide, allowing selective introduction of chlorine, bromine or cyano groups in 2- and 2′-postions of the chiral atropisomeric 4,4′-bipyridines. The crystal packing in the solid state of some newly prepared derivatives was analyzed and revealed the importance of halogen bonds in intermolecular interactions. Full article
(This article belongs to the Special Issue Feature Papers in Compounds)
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12 pages, 3451 KiB  
Article
A Novel Quinoxaline-Rhodamine Conjugate for a Simple and Efficient Detection of Hydrogen Sulphate Ion
by Sutapa Sahu, Yeasin Sikdar, Riya Bag, Dilip K. Maiti, José P. Cerón-Carrasco and Sanchita Goswami
Compounds 2021, 1(1), 29-40; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010004 - 08 Apr 2021
Cited by 3 | Viewed by 2934
Abstract
This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (HSO4) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for [...] Read more.
This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (HSO4) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for HSO4 are small as 0.71 µM and 3.8 µM for the absorption and emission experiments, respectively. The effectiveness of the probe in recognizing HSO4 both in gel and solid phase is evaluated as well. Thus, this works presents a simple strategy to detect the environmental HSO4 pollutant event at tiny concentrations. Full article
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12 pages, 3479 KiB  
Article
Hf-Based UiO-66 as Adsorptive Compound and Oxidative Catalyst for Denitrogenation Processes
by Rui G. Faria, Diana Julião, Salete S. Balula and Luís Cunha-Silva
Compounds 2021, 1(1), 3-14; https://0-doi-org.brum.beds.ac.uk/10.3390/compounds1010002 - 19 Jan 2021
Cited by 8 | Viewed by 5096
Abstract
A series of porous metal–organic frameworks (MOFs) of the UiO-66 family, namely UiO-66(Zr), UiO-66(Hf) and UiO-66(Hf)-NH2, prepared by solvothermal procedures were characterized, and their catalytic efficiency for oxidative denitrification (ODN) was investigated for the first time. Sustainable denitrogenation systems combining adsorption [...] Read more.
A series of porous metal–organic frameworks (MOFs) of the UiO-66 family, namely UiO-66(Zr), UiO-66(Hf) and UiO-66(Hf)-NH2, prepared by solvothermal procedures were characterized, and their catalytic efficiency for oxidative denitrification (ODN) was investigated for the first time. Sustainable denitrogenation systems combining adsorption and oxidative catalytic capacity were designed using a model diesel containing two distinct nitrogen compounds (NCs) in a solvent-free medium and using an environment-friendly oxidant (H2O2). An efficient adsorptive denitrogenation process was only achieved after long reaction times (24 h): using the Hf-based MOFs, the adsorptive denitrogenation increased from 19% to 79% at 5 to 24 h, while the UiO-66(Zr) reached 76% after 24 h, although the absence of adsorption capacity after 5 h. UiO-66(Hf) and UiO-66(Hf)-NH2 also revealed superior oxidative catalytic denitrogenation than UiO-66(Zr), attaining 97% of efficiency instead of 80%. ODN processes demonstrated to be more effective than the adsorptive denitrogenation, mainly during the first hours of the process. In addition, the metal center in the MOF structure had a larger influence than the presence of the amine-functional groups. Hf-based compounds revealed higher denitrogenation efficiency than the UiO-66(Zr) for a shorter reaction time (5 h). Full article
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