Hydroxy Group Research Articles

Biobased partially crosslinked polyβ-hydroxyesters synthesized from low-melt carboxyl-polyamides and a dicyclocarbonate

A new kind of biobased partially crosslinked polyβ-hydroxyesters (cPHEs) was synthesized through the ring-opening polymerization of a five-membered dicyclocarbonate and carboxyl-terminated dimer acid (DA) oligopolyamides (DAPAcs). The DAPAcs provided carboxyl groups and attacked the cyclocarbonate groups to form β-hydroxyester units, which was confirmed by a model reaction. DAPAcs were synthesized from hexamethylenediamine and excess DA. Their structure and properties were confirmed by FTIR, 1H NMR, and DSC. cPHEs exhibited semicrystalline characters with good thermal properties evidenced by wide-angle X-ray scattering, DSC, and TGA. Introducing DAPA sequences improved intermolecular interactions and tensile strength. The attack of pendent hydroxy groups to remaining cyclocarbonate groups led to crosslinked cPHEs. Dynamic β-hydroxylester segments impart the reprocessability of cPHEs, and stress relaxation experiments were conducted at different temperatures to evaluate the exchange kinetics. A new synthetic route different from normal epoxy-carboxyl route was established. This method broadens the research of polyβ-hydroxylesters and their application range.

Controlling polymer degradation by addition of plant aromatic polymer, lignin

This study examined the accelerated degradation of poly(caprolactone) films using two types of lignin derivatives. The degradation of poly(caprolactone) films was unaffected by the lignin derivative capped hydroxy groups, indicating the participation of radicals from phenolic hydroxy groups in lignin derivatives for accelerating the degradation of films. Furthermore, the role of lignin radicals in relation to polymer degradation changed as per the mechanism of polymer decomposition, e.g., the degradation of poly(ethylene carbonate) films was suppressed by feeding lignin derivatives because of the back biting type decomposition nature of poly(ethylene carbonate), which differs from the radical-mediated addition/cleavage type decomposition nature of poly(caprolactone). These results provide an approach of designing bio-degradative materials from lignin, a natural phenolic polymer.

Difluorocarbene Enables Access to 2,2-Difluorohydrobenzofurans and 2-Fluorobenzofurans from ortho-Vinylphenols.

2-Fluorobenzofurans are the backbone structures of many drug molecules and have many potential therapeutic bioactivities. Despite the potential applications in medicinal chemistry, practical and efficient synthetic methods for the construction of 2-fluorobenzofuran are very limited. Herein, we report an efficient and general method for the construction of 2-fluorobenzofurans. Contrary to the previous functionalizations of the existing backbone of benzofuran, our strategy directly constructs benzofuran scaffolds alongside the incorporation of fluorine atom on C2 position in a formal [4 + 1] cyclization from readily accessible ortho-vinylphenols and difluorocarbene. In our strategy, ClCF2H decomposes into difluorocarbene in the presence of base, which is further captured by the oxygen anion from the hydroxy group in ortho-hydroxychalcones; subsequent intramolecular Michael addition to the α, β-unsaturated system leads to 2,2-difluorohydrobenzofurans, and further fluorine elimination renders 2-fluorobenzofurans by forming one C-O bond and one C-C double bond. Of note, various complex 2,2-difluorohydrobenzofurans and 2-fluorobenzofurans could be readily accessed through our protocol via the late-stage elaborations.

STUDYING THE EFFECT OF ADDING LIGNOSULFONATE STABILIZERS ON THE STRUCTURAL, THERMAL AND OPTICAL PROPERTIES OF POLYMERS POLYVINYL ALCOHOL

Composite films made from blends ofPolyvinyl Alcohol (PVA) and Lignosulfonate (LS) were prepared using the casting technique in this study.The aim was to investigate the impact of LS concentrations at (0, 0.01, 0.05, and 0.1 wt. %) on the optical, thermal, and structural properties of PVA.The composite films were examined using X-ray diffraction (XRD) and UV-VIS spectroscopy. Results showed that adding LS led to a more compact structural arrangement, increasing the refractive index and amorphous phase due to the composites disorder, which reduced the optical energy gap. The Absorbance of the PVA/LS composite film increased as LS concentration increased, indicating a strong intermolecular interaction between LS and PVA. This interaction suggested a strong hydrogen bond formation between the hydroxy group in PVA chains and the outer site groups of LS. These findings suggest that LS can effectively modulate the optical properties of PVA, making it useful in various fields such as optics and photonics.

Synthesis and Utilization of 1H-Indazole N-Oxides in the Production of C3-Functionalized 1H-Indazoles

The medicinal importance, natural rarity, and challenges associated with the synthesis of C3-functionalized 1H-indazoles have propelled the development of novel and practical 1H-indazole N-oxides for the production of diverse arrays of C3-functionalized 1H-indazoles. Utilizing 1H-indazole N-oxides has demonstrated remarkable efficacy in selectively introducing diverse functional groups, including amino (–NHAr), chloro (–Cl), hydroxy (–OH), sulfonyl (–SO2Ar), aromatic (–Ar), olefin, alkyl, and N-formyl (–NRCHO) groups, to indazole pharmacophore molecules. This review aims to offer a concise overview of synthetic approaches and practical applications of 1H-indazole N-oxides, including recent studies conducted by the authors. Transformative reactions involving 1H-indazole N-oxides not only offer strategies for synthesizing C3-functionalized 1H-indazoles but also hold significant potential in medicinal chemistry.

Controlled Enzymatic Synthesis of Polyesters Based on a Cellulose-Derived Triol Monomer: A Design of Experiment Approach.

Regioselective enzymatic polycondensation of the bio-based cellulose derived polyol, Triol-citro, and dimethyl adipate using Candida antarctica Lipase B (CaLB) was investigated. A Design of Experiment approach with MODDE® Pro 13 was used to determine important factors in the branching behavior of this polymer, and reactant ratio, temperature, reaction time and enzyme wt % were the studied factors. Multifunctional polyesters with pendant hydroxy groups were synthesized and fully characterized using 2D NMR techniques to determine degree of branching. Branching was minimal, with a maximum of 16 % observed, and monomer ratio, temperature and reaction time were all determined to be significant factors. In this work, Mn of up to 13 kDa were achieved, while maintaining degree of branching below 15 %, resulting in a linear polyester with the potential to be further functionalized.

Bioinspired All‐Polyester Diblock Copolymers Made from Poly(Pentadecalactone) and Poly(3,4‐Ethylene Furanoate): Synthesis and Polymer Film Properties

AbstractBio‐based, fully degradable aliphatic‐aromatic block copolymers are synthesized from ω‐pentadecalatone and cyclic oligo(3,4‐ethylene furanoate). In the first approach, the ring‐opening polymerization of the cyclic oligo(3,4‐ethylene furanoate) is initiated by a poly(pentadecalactone) macroinitiator with a terminal hydroxy group. The reaction temperatures of the melt polymerization are 210–230 °C due to the high melting points of the oligo(3,4‐ethylene furanoate). Under these conditions, transesterification is observed. The blockiness of the reaction products depends on the reaction temperature and on the ratio of pentadecalactone to 3,4‐ethylene furanoate repeat units, which is 50:50, 80:20, and 90:10. At lower temperatures and more pentadecalactone content, the blockiness is larger. The number average molar mass of the block copolymers remains smaller than 20 000 g mol−1. In the second approach, poly(pentadecalactone) is functionalized with an alkyne group, and the OH group of the oligo(3,4‐ethylene furanoate) (molar mass 1900 g mol−1) is converted into an azide group. Connecting the two polymers in a copper‐catalyzed 1,3‐dipolar addition reaction (“click reaction”) yields block copolymers with a number average molar mass of 12 400 g mol−1. The mechanical properties of the polymer films are intermediate between those of the parent homopolymers.

Alkynyl Gold(I) Phosphine Complexes: Evaluation of Structure–Activity Relationships for the Alkynyl Ligands on Luminescence and Cytotoxicity

AbstractA series of gold (I) phoshpine complexes with diverse alkynyl ligands [Au(C≡CR)(PTA)] (R=C6H11OH, 1; C5H9OH, 2; C15H11OH, 3; C19H27O2, 4; C18H23O2, 5; C9H12N, 6; CH2OCH2C6H5, 7; C6H4OCH3, 8; PTA=1,3,5‐Triaza‐7‐phosphaadamantane) have been synthesized and characterized using a range of spectroscopic techniques. Complex 1 and 3 show an infinite one–dimensional S–type and zigzag aurophilic chain, respectively, whereas complex 2 containing 1‐ethynyl‐1‐cyclohexanol gives an approximate linear two–dimensional aurophilic chain, through intra/intermolecular Au(I)⋯Au(I) interactions as well as hydrogen bonding interactions between hydroxy groups of alkynyl ligands and PTA. Solid complexes 1–8 display strongly room/low–temperature emissive of 477–613 nm with the emission lifetime of 0.40–14.0 μs. All the complexes display higher cytotoxicities against MCF‐7, with the cytotoxicity decreasing in the following order 4>8>5>3>7>6>2>1. Complex 4 and 5 stand out for the highest selectivity towards MCF–7 (IC50=0.63–0.78 μM) compared with normal human embryonic lung fibroblasts (helf) (IC50=14.85–18.13 μM), which makes those complexes attractive for breast cancer therapy.

Surface Engineering of Tin Oxide Nanoparticles by pH Modulation Facilitates Homogeneous Film Formation for Efficient Perovskite Solar Modules

AbstractUniform film deposition over an entire substrate is indispensable to achieve efficient perovskite solar modules (PSMs) by minimizing the gap with high‐performance perovskite solar cells (PSCs). Only a few microscopic pinholes on the film in PSMs directly give rise to debase the performance and stimulate the degradation of the devices. Herein, a strategy of the homogeneous and defect‐reduced electron‐transport layer for high‐performance PSMs is reported. pH modulation of tin oxide (SnO2) nanoparticles colloidal dispersion by a small amount of nitric acid (HNO3) addition leads to the removal of hydroxy groups on the SnO2 surface acting as electronic defects as well as superb regularity of the thin films by forming a network of the SnO2 nanoparticles. The surface engineering of SnO2 nanoparticles brings out the high performance of 23.7% efficiency for a unit cell, 20.3% efficiency for a 24.5 cm2 minimodule, and 19.0% efficiency for a 214.7 cm2 submodule, respectively, where all efficiencies are averaged from results obtained by the reverse/forward scan. In outdoor tests with the submodules, a target PSM generates 16.5% higher cumulative electricity for a month as compared to a control PSM. Furthermore, under damp heat environments, the target PSM maintains 80% efficiency compared to an initial efficiency of 1080 h.

Syntheses, crystal structures, and fluorescence properties of two new copper phosphonates from hydroxy-functionalized bisphosphonic acid ligand

Exploring metal phosphonates with new crystal structures is of significance for the development of metal-organic frameworks (MOFs). In this work, two new copper phosphonates, [tetraauqa-1,4-phenylenebis(hydroxymethylene))bisphosphonate biscopper(II)] bishydrate [Cu2(H2L)(H2O)4]·2H2O (1) and 1,4-phenylenebis(hydroxymethylene))bisphosphonate-(4,4’-bipy) copper(II) [Cu(H4L)(4,4’-bipy)] (2) (4,4’-bipy = 4,4’-bipyridine), have been synthesized from a hydroxy functionalized bisphosphonate ligand, H6L = (1,4-phenylenebis(hydroxymethylene))bis(phosphonic acid). The introduction of a hydroxy group can regulate the crystal structures. The bisphosphonate ligand in 1 is hexadentate, binding six copper ions with its six phosphonate oxygen atoms and two hydroxy oxygen atoms, forming a three-dimensional framework structure with rectangle channels running along the b-direction. For 2, the bisphosphonate ligands are double deprotonated and chelate or bridge two copper ions, showing a two-dimensional layered crystal structure. These compounds have interesting fluorescence properties with emission maxima (307 and 410 nm) lying in the blue region.

Fully Polymeric Conductive Hydrogels with Low Hysteresis and High Toughness as Multi‐Responsive and Self‐Powered Wearable Sensors

AbstractHigh mechanical strength, excellent toughness, low hysteresis, and robust resilience are of great importance for stretchable conductive hydrogels (CHs) to heighten their reliabilities for self‐powered sensing applications. However, it still remains challenging to simultaneously obtain the mutually exclusive performances. Herein, an intrinsically conductive and adhesive hydrogel is fabricated by one‐step radical polymerization of acrylamide (AAm), three hydroxy groups together clustered‐N‐[tris(hydroxymethyl)methyl]acrylamide (THMA), and cationic 1‐Butyl‐3‐Vinylimidazolium Bromide (ILs) dissolved in core‐shell structurally dispersed PEDOT:PSS (PP) solution. Owing to abundant clustered hydrogen bonds, electrostatic interactions between PILs chains and anionic PSS shells, and polymer chain entanglements, the CHs feature superior mechanical properties with a high tensile strength (0.25 MPa), fracture strain (1015%), fracture toughness (1.22 MJ m‐3), fracture energy of 36.5 kJ m‐2 and extremely low hysteresis (5%), and display excellent resilience and fatigue resistance. As a result, the CHs indicate excellent sensing properties with a gauge factor up to 10.46, a broad sensing range of strain (1‐900%) and pressure (0.05‐100 kPa), and fast responsive rate, thus qualifying for monitoring reliably and accurately large and tiny human movements in daily life. Moreover, the hydrogel‐assembled triboelectric nanogenerators (TENGs) exhibit excellent and stable electrical output performances, which are greatly promising in self‐powered flexible wearable electronics.

Effect of hydroxy groups on structural, electronic, and biological properties of methyl carbazate containing hydroxy benzaldehyde-based imines. A combined experimental and theoretical investigation

Interactions present in differently substituted hydroxy based imine derivatives were characterised and identified by the utilisation of spectroscopic techniques in conjunction with X-ray crystallography and theoretical computations. All the target compounds ‘a-c’ crystallises in monoclinic crystal system with P21/c and C2/c space groups. CH…Pi and Pi…Pi interaction are the characteristic interactions present in the target compounds ‘a-c’ The most significant contributions to the crystal packing were found using Hirshfeld surface analysis, and potential contact points were identified. H…H, O…H and C…H contacts and π stacking interactions are the dominant contacts observed in all the crystals these results showed that hydrogen bonding and hydrophobic interactions were significantly present. Furthermore, investigations related to calculations of the molecular electrostatic potential and frontier molecular orbital (highest occupied–lowest unoccupied) were carried out for the optimised structure. The HOMO-LUMO energy gap made it possible to determine the molecule's chemical hardness, chemical inertness, electronegativity, and electrophilicity index, which showed its possible kinetic stability and reactivity. The target compounds' predicted activity spectra (PASS) showed that these compounds exhibit significant Testosterone 17beta-dehydrogenase (NADP+) inhibition activity, with Pa 7.18–7.95. Finally, Testosterone 17beta-dehydrogenase (NADP+) (PDB-ID 3KLP) was used to conduct molecular docking investigations of compounds ‘a-c’. Due to their tiny size and lack of rigidity, which enable them to bind well at any position, a and b exhibit higher binding free energies of -7.08 and -7.00 kcal/mol and inhibition constants of 0.1 and 1.2 µM than compound c.

Selective C(aryl)-O bond cleavage in biorenewable phenolics.

Biorefining of lignocellulosic biomass via a lignin first approach delivers a range of products with high oxygen content. Besides pulp, a lignin oil rich in guaiacols and syringols is obtained bearing multiple C(aryl)-OH and C(aryl)-OMe groups, typically named phenolics. Similarly, technical lignin can be used but is generally more difficult to process providing lower yields of monomers. Removal of the hydroxy and methoxy groups in these oxygenated arenes is challenging due to the inherently strong C-O bonds, in addition to the steric and electronic deactivation by adjacent -OH or -OMe groups. Moreover, chemoselective removal of a specific group in the presence of other similar functionalities is non-trivial. Other side-reactions such as ring saturation and transalkylation further complicate the desired reduction process. In this overview, three different selective reduction reactions are considered. Complete hydrodeoxygenation removes both hydroxy and methoxy groups resulting in benzene and alkylated derivatives (BTX type products) which is often complicated by overreduction of the arene ring. Hydrodemethoxylation selectively removes methoxy groups in the presence of hydroxy groups leading to phenol products, while hydrodehydroxylation only removes hydroxy groups without cleavage of methoxy groups giving anisole products. Instead of defunctionalization via reduction transformation of C(aryl)-OH, albeit via an initial derivatization into C(aryl)-OX, into other functionalities is possible and also discussed. In addition to methods applying guaiacols and syringols present in lignin oil as model substrates, special attention is given to methods using mixtures of these compounds obtained from wood/technical lignin. Finally, other important aspects of C-O bond activation with respect to green chemistry are discussed.

Donor effect on the B ← N dative bond directed dye sensitized solar cell application

This paper shows the use of B ← N triel bonding interactions in dye-sensitized solar cells (DSSCs) through molecular modeling involving different donor groups based on acceptors like Borinic acids, Boronic acid, and Boric acid. Our computed data shows that Pyrrolizine donor-based dye sensitizers show better efficiency than the other donors used in this work due to their lower distortion between the acceptor and the rest part of the dye, which indicates easier transfer of electrons. We also observed that Borinic acid spacer-based dyes showed better injection (ΔGinject) and regeneration efficiency (ΔGregen) as well as better short-circuit current density (JSC) and open circuit voltage (VOC) which are important for the higher efficiency which is due to the increase of the B ← N bond distances as we increase the number of hydroxy groups from (OH)1 to (OH)3 resulting in lower charge transfer.

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus.

Drimane-type sesquiterpenoids (DMTs) are characterized by a distinctive 6/6 bicyclic skeleton comprising the A and B rings. While DMTs are commonly found in fungi and plants, their presence in bacteria has not been reported. Moreover, the biosynthetic pathways for DMTs have been primarily elucidated in fungi, with identified P450s only acting on the B ring. In this study, we isolated and characterized three bacterial DMTs, namely 3β-hydroxydrimenol (2), 2α-hydroxydrimenol (3), and 3-ketodrimenol (4), from Streptomyces clavuligerus. Through genome mining and heterologous expression, we identified a cav biosynthetic gene cluster responsible for the biosynthesis of DMTs 2-4, along with a P450, CavA, responsible for introducing the C-2 and C-3 hydroxy groups. Furthermore, the substrate scope of CavA revealed its ability to hydroxylate drimenol analogs. This discovery not only broadens the known chemical diversity of DMTs from bacteria, but also provides new insights into DMT biosynthesis in bacteria.

Improved flame resistance and thermal insulation properties of steel fireproof coatings based on polyvinyl alcohol @ expandable graphite

Intumescent fireproof coating (IFC) can effectively slow down the temperature rise of base materials by constructing intumescent heat isolation chars. Expandable graphite (EG), combined with a typical intumescent flame-retardant system, shows an excellent expansion effect. However, it is difficult to be evenly dispersed in the coating system due to its low surface energy, thus limiting its application in IFC. In this research, EG encapsulated by polyvinyl alcohol (PVA) film was used in combination with conventional intumescent flame retardants to prepare a fireproof coating. Due to the increased hydrophilicity caused by the hydroxy groups of the PVA, both the dispersion and adhesion of EG can be greatly improved in the coating. Additionally, PVA also plays the role of a charring agent to further upgrade the quality of the produced carbon layer. The prepared IFC displays a satisfying synergistic effect. The experimental results showed that the back-surface temperature of the steel plate coated by PVA@EG was reduced to 232 °C after 20 min, far lower than the 250 °C of the unmodified EG system, and the thermal insulation performance was enhanced significantly. Compared with the untreated EG coating, the HRR, THR, and TSR decreased by 79.5 %, 86.0 % and 24.8 %, respectively, and combustion and smoke suppression performance were improved greatly. All in all, PVA@EG endows the coating with superior flame-retardant and thermal insulation performance and greatly improves the safety of steel structures in buildings.

Epoxide Ring‐Opening Reactions for Abundant Production of Mugineic Acids and Nicotianamine Probes

AbstractA succinct synthetic approach to mugineic acids and 2’‐hydroxynicotianamine was established. Unlike all other synthetic methods, this approach utilized epoxide ring‐opening reactions to form two C−N bonds and is characterized by the absence of redox reactions. Mugineic acid was synthesized from three readily available fragments on a gram scale in 6 steps. The protected 2’‐hydroxynicotianamine was also synthesized in 4 steps, and the dansyl group, serving as a fluorophore, was introduced through a click reaction after propargylation of the 2’‐hydroxy group. The dansyl‐labeled nicotianamine (NA) iron complexes were internalized by oocytes overexpressing ZmYS1 (from maize) or PAT1 (from human) transporters, indicating successful transport of the synthesized NA‐probe through these transporters.

Molecular Iodine as a Catalyst for Alkene Difluorination.

The difluorination reaction of alkenes catalyzed by molecular iodine was revealed for the first time. This difluorination reaction affords a simple and practical experimental method and can be applied to many aliphatic and aromatic alkenes bearing synthetically useful functional groups, such as ester, amide, hydroxy, and aryl groups. Preliminary mechanistic studies of this alkene difluorination suggest the existence of two catalytic cycles: the IF-driven cycle and the catalytic cycle by the IF adduct.

Elucidation of Palmarumycin Spirobisnaphthalene Biosynthesis Reveals a Set of Previously Unrecognized Oxidases and Reductases.

Spirobisnaphthalenes (SBNs) are a class of highly oxygenated, fungal bisnaphthalenes containing a unique spiroketal bridge, that displayed diverse bioactivities. Among the reported SBNs, palmarumycins are the major type, which are precursors for the other type of SBNs structurally. However, the biosynthesis of SBNs is unclear. In this study, we elucidated the biosynthesis of palmarumycins, using gene disruption, heterologous expression, and substrate feeding experiments. The biosynthetic gene cluster for palmarumycins was identified to be distant from the polyketide synthase gene cluster, and included two cytochrome P450s (PalA and PalB), and one short chain dehydrogenase/reductase (PalC) encoding genes as key structural genes. PalA is an unusual, multifunctional P450 that catalyzes the oxidative dimerization of 1,8-dihydroxynaphthalene to generate the spiroketal linkage and 2,3-epoxy group. Chemical synthesis of key intermediate and in vitro biochemical assays proved that the oxidative dimerization proceeded via a binaphthyl ether. PalB installs the C-5 hydroxy group, widely found in SBNs. PalC catalyzes 1-keto reduction, the reverse 1-dehydrogenation, and 2,3-epoxide reduction. Moreover, an FAD-dependent oxidoreductase, encoded by palD, which locates outside the cluster, functions as a 1-dehydrogenase. These results provided the first genetic and biochemical evidence for the biosynthesis of palmarumycin SBNs.

Biological activity and computational analysis of novel acrylonitrile derived benzazoles as potent antiproliferative agents for pancreatic adenocarcinoma with antioxidative properties

Continuing our research into the anticancer properties of acrylonitriles, we present a study involving the design, synthesis, computational analysis, and biological assessment of novel acrylonitriles derived from methoxy, hydroxy, and N-substituted benzazole. Our aim was to examine how varying the number of methoxy and hydroxy groups, as well as the N-substituents on the benzimidazole core, influences their biological activity. The newly synthesized acrylonitriles exhibited strong and selective antiproliferative effects against the Capan-1 pancreatic adenocarcinoma cell line, with IC50 values ranging from 1.2 to 5.3 μM. Consequently, these compounds were further evaluated in three other pancreatic adenocarcinoma cell lines, while their impact on normal PBMC cells was also investigated to determine selectivity. Among these compounds, the monohydroxy-substituted benzimidazole derivative 27 emerged with the most profound and broad-spectrum anticancer antiproliferative activity being emerged as a promising lead candidate. Moreover, a majority of the acrylonitriles in this series exhibited significant antioxidative activity, surpassing that of the reference molecule BHT, as demonstrated by the FRAP assay (ranging from 3200 to 5235 mmolFe2+/mmolC). Computational analysis highlighted the prevalence of electron ionization in conferring antioxidant properties, with computed ionization energies correlating well with observed activities.