Long-chain Substituents Research Articles

Irciniaplysins A-D: New Psammaplysin Derivatives from Philippine Marine Sponge Ircinia sp.

Four new psammaplysin derivatives (1-4) with fatty acyl substituents, designated irciniaplysins A-D, and three known psammaplysins (5-7) were isolated from a marine sponge Ircinia sp. Their structures were elucidated using extensive spectroscopic analyses. The positions of the double bonds and the branch points of the fatty acyl side chains were determined by GC-MS analysis of their fatty acid methyl ester (FAME) derivatives. Irciniaplysins A (1) and B (2) contained an unusual long-chain fatty acyl substituent with a 5,9-diene unit. The isolated compounds were evaluated for their cytotoxic activity against the human colorectal carcinoma (HCT 116) cells, however, none of these compounds showed significant activity.

Functionalization and Structural Evolution of Conducting Quasi-One-Dimensional Chevrel-Type Telluride Nanocrystals.

Interfacing organic molecular groups with well-defined inorganic lattices, especially in low dimensions, enables synthetic routes for the rational manipulation of both their local or extended lattice structures and physical properties. While appreciably studied in two-dimensional systems, the influence of surface organic substituents on many known and emergent one-dimensional (1D) and quasi-1D (q-1D) crystals has remained underexplored. Herein, we demonstrate the surface functionalization of bulk and nanoscale Chevrel-like q-1D ionic crystals using In2Mo6Te6, a predicted q-1D Dirac semimetal, as the model phase. Using a series of alkyl ammonium (-NR4+; R = H, methyl, ethyl, butyl, and octyl) substituents with varying chain lengths, we demonstrate the systematic expansion of the intrachain c-axis direction and the contraction of the interchain a/b-axis direction with longer chain substituents. Additionally, we demonstrate the systematic expansion of the intrachain c-axis direction and the contraction of the interchain a/b-axis direction as the alkyl chain substituents become longer using a combination of powder X-ray diffraction and Raman experiments. Beyond the structural modulation that the substituted groups can impose on the lattice, we also found that the substitution of ammonium-based groups on the surface of the nanocrystals resulted in selective suspension in aqueous (NH4+-functionalized) or organic solvents (NOc4+-functionalized), imparted fluorescent character (Rhodamine B-functionalized), and modulated the electrical conductivity of the nanocrystal ensemble. Altogether, our results underscore the potential of organic-inorganic interfacing strategies to tune the structural and physical properties of rediscovered Chevrel-type q-1D ionic solids and open opportunities for the development of surface-addressable building blocks for hybrid electronic and optoelectronic devices at the nanoscale.

Catalyst self-assembly accelerates bimetallic light-driven electrocatalytic H2 evolution in water.

Hydrogen evolution is an important fuel-generating reaction that has been subject to mechanistic debate about the roles of monometallic and bimetallic pathways. The molecular iridium catalysts in this study undergo photoelectrochemical dihydrogen (H2) evolution via a bimolecular mechanism, providing an opportunity to understand the factors that promote bimetallic H-H coupling. Covalently tethered diiridium catalysts evolve H2 from neutral water faster than monometallic catalysts, even at lower overpotential. The unexpected origin of this improvement is non-covalent supramolecular self-assembly into nanoscale aggregates that efficiently harvest light and form H-H bonds. Monometallic catalysts containing long-chain alkane substituents leverage the self-assembly to evolve H2 from neutral water at low overpotential and with rates close to the expected maximum for this light-driven water splitting reaction. Design parameters for holding multiple catalytic sites in close proximity and tuning catalyst microenvironments emerge from this work.

Environmentally friendly and efficient TBHP-mediated catalytic reaction for the synthesis of substituted benzimidazole-2-ones: In-silico approach to pharmaceutical applications

A novel method was used to synthesize benzimidazole-2-ones from the corresponding benzimidazolium salts. These salts were subsequently reacted with potassium tertiary butoxide (KOtBu), followed by oxidation using tertiary butyl hydrogen peroxide (TBHP) at room temperature in tetrahydrofuran (THF) to obtain the desired products in 1 h with excellent yields. After optimizing the reaction conditions, the study focused on preparing benzimidazole-2-ones with diverse substituents at N1 and N3 positions, including benzyl, 2′,4′,6′-trimethyl benzyl groups, and long-chain aliphatic substituents (hexyl, octyl, decyl, and dodecyl). The compounds were characterized by 1H and 13C NMR spectra, of which compound 2a is supported by single crystal XRD. Benzimidazole-2-one compounds exhibited promising anti-inflammatory and anti-cancer properties. The inhibition of mitochondrial Heat Shock Protein 60 (HSP60) of title compounds was also explored. Computational simulations were employed to assess anti-cancer properties of 19 benzimidazole-2-one derivatives (potential drugs). In-silico docking studies demonstrated promising binding interactions with HSP60, and these results were supported by molecular dynamics simulations. Notably, molecules 2b and 2d exhibited high affinity for HSP60 protein, highlighting their potential efficacy. The developed ligands were viable for the treatment of hepatocellular carcinoma (HCC). The findings provide valuable initial evidence supporting the efficacy of benzimidazole-2-ones as HSP60 inhibitors and lay the foundation for subsequent studies, including in-vitro assays.

High-dose exposure to butylparaben impairs thyroid ultrastructure and function in rats

Parabens (PBs) are a class of preservatives commonly used in cosmetics and pharmaceuticals. Studies have shown that these compounds may act as endocrine disruptors, affecting thyroxine levels in humans. PBs with longer chain substituents, such as butylparaben (BuP), are less prone to complete biotransformation and are therefore more likely to accumulate in the body. In this study, the effect of high-dose exposure to BuP on thyroid microstructure, ultrastructure, and function was investigated in rats. 50 mg/kg bw per day of BuP was injected subcutaneously into the neck of rats for 4 weeks. Rat thyroid weight, microstructure, and ultrastructure were determined, and the levels of thyroid sodium/iodide symporter (NIS), serum thyroid hormones, and thyroid autoantibodies were measured. The human thyroid cell line was used to study the mechanism of BuP on thyroid epithelial cells. The weight of the thyroid gland of BuP-exposed rats was increased, the structure of the thyroid follicles was irregular and damaged, the mitochondria and rough endoplasmic reticulum were swollen and damaged, and the microvilli at the tip of the epithelium were reduced and disappeared. Serum total T3, total T4, free T3, and free T4 were decreased in BuP-exposed rats, and TSH, peroxidase antibody, and thyroglobulin antibody were increased. In vitro, BuP decreased the level of NIS in thyroid epithelial cells, inhibited proliferation and viability, and induced apoptosis in a dose-dependent manner. This study demonstrated that high-dose exposure to BuP induced structural, ultrastructural, and functional impairment to the thyroid gland of rats, which may be one of the factors leading to hypothyroidism.

Exploring copper (II) porphyrin complexes and their derivatives for electrochemical analysis and biological assessment in the study of breast cancer (MCF-7) cell lines

In this study, several derivatives of tetraphenylporphyrin were synthesized, each with unique meso-substituent groups including phenyl, methoxyphenyl, butyloxyphenyl, octyloxyphenyl, and dectyloxyphenyl. Additionally, their corresponding copper complexes were prepared and thoroughly characterized. The structural confirmation of all compounds was established through CHN elemental analysis, mass spectrometry, and FT-IR spectroscopy. As the number of carbon atoms in the alkyl long-chain increased, a slight red shift in the electronic absorption band was observed, which was attributed to the electronic influence of the alkyl group. DFT analysis indicated that electron density predominantly localized on the porphyrin ring of both the metal free porphyrins and copper (II) porphyrin complexes, with relatively low electron density in the p orbital of the meso-aryl long-chain substituent group. EPR spectroscopy of the Copper (II) ion complexes revealed signals, indicating their paramagnetic properties. Additionally, the Copper (II) tetraphenylporphyrin (CuTPP) complexes displayed two reversible oxidation peaks at +0.97 V and +1.35 V, whereas other derivatives exhibited lower oxidation potentials. The cytotoxicity of these compounds against MCF-7 cell lines was assessed using MTT assay, revealing cytotoxic effects in all cases. Among them, Copper (II) tetrakis (4-methyloxyphenyl)porphyrin (CuTOMPP) demonstrated the highest potential, with an IC50 value of 32.07 μg/mL.

Design, synthesis, biological evaluation and molecular docking of alkoxyaurones as potent pancreatic lipase inhibitors

Aurones are a minor subgroup of flavonoids. Unlike other subgroups such as chalcones, flavones, and isoflavones, aurones have not been extensively explored as pancreatic lipase inhibitors. In this work, we studied the pancreatic lipase inhibitory potency of synthetic aurone derivatives. Thirty-six compounds belonging to four series (4,6-dihydroxyaurone, 6-hydroxyaurone, 4,6-dialkoxyaurone, and 6-alkoxyaurone) were designed and synthesized. Their in vitro inhibitory activities were determined by spectrophotometric assay in comparison with quercetin and orlistat. Alkoxyaurone derivatives with long-chain (6–10 carbons) alkoxy substituents showed greater potency. Of them, 4,6-dialkoxyaurone 8 displayed the highest activity against pancreatic lipase (IC50 of 1.945 ± 0.520 µM) relative to quercetin (IC50 of 86.98 ± 3.859 µM) and orlistat (IC50 of 0.0334 ± 0.0015 µM). Fluorescence quenching measurement confirmed the affinity of alkoxyaurone derivatives to pancreatic lipase. Kinetic study showed that 8 inhibited lipase through a competitive mechanism (Ki of 1.288 ± 0.282 µM). Molecular docking results clarified the role of long-chain substituents on ring A in interacting with the hydrophobic pockets and pushing the inhibitor molecule closer to the catalytic triad. The findings in this study may contribute to the development of better pancreatic lipase inhibitors with aurone structure.

Open Zn-URJC-13 efficient catalyst for mild CO2 transformation using bulky epoxides

In CO2 cycloaddition reactions with epoxides that have bulky or long-chain substituents, the yield significantly decreases when using heterogeneous catalysts, including MOFs, with micropores smaller than 14 Å. In this study, a new MOF material called Zn-URJC-13 is reported. This MOF combines different features such as that it contains acid and basic Lewis sites based on Zn and -NH2 groups, exhibits permanent porosity with a bimodal porous system centered at 11 and 17 Å suitable for the diffusion of cycloaddition reaction species, and it is chemically stable in various common organic solvents. The aim of this material is to improve the textural properties of other MOFs with similar chemical compositions, making it suitable as a catalyst for CO2 cycloaddition reactions with epoxides even bulky. This novel material exhibits high affinity to CO2 molecules, with a Qst of 62 kJ/mol. The Zn-URJC-13 catalyst demonstrates efficient performance in CO2 cycloaddition reactions using a wide range of epoxides, including those with long-chain and bulky substituents such as allyl glycidyl ether and styrene oxide. It can achieve an epoxide conversion as high as 84 % and selectivity to carbonate products above 90 % for the bulkiest styrene oxide. When compared to other Zn-based MOF materials with similar or different structures but without amino groups, the new material exhibits superior catalytic performance. Furthermore, Zn-URJC-13 can be reused in five consecutive reaction cycles while maintaining its efficient catalytic behavior and crystalline structure. These findings highlight the notable potential of Zn-URJC-13 for CO2 cycloaddition transformation routes.

STEARIN AS A STARTING MATERIAL FOR THE SYNTHESIS OF BIOLOGICALLY ACTIVE IONIC LIQUIDS

For the first time, the possibility of using widely available stearin for the production of fatty acid-derived ionic liquids (ILs) has been shown. New amphiphilic ILs based on imidazolium, pyridinium, and quaternary ammonium cations containing long-chain alkyl substituents were obtained. The synthesized compounds are shown to have biological activity comparable to known antimicrobial compounds. ILs with one alkyl substituent have higher cytotoxicity and antimicrobial activity compared to disubstituted derivatives.

SYNTHESIS AND CHEMICAL PROPERTIES OF 2-HEPTADECYL-[1,3]THIAZOLO[3,2-b][1,2,4]TRIAZOL-7-IUM CATION

Functional and condensed derivatives of 1,2,4-triazoles are mostly used as biologically active compounds, and modern studies increasingly report their successful use as surfactants, stabilizers for the formation of nanoparticles, components of hybrid perovskites, which are promising materials for opto-electronics.
 Synthesis of new [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts containing a long-chain heptadecyl substituent was proposed within our research. The production of the starting compounds (2-heptadecyl-4-methyl-1,2,4-triazole-3-thione and methallyl thioether of 2-heptadecyl-3-mercapto-4-methyl-1,2,4-triazole) was carried out according to a modified method annelating of the triazole ring to combined hybrid polyheterocyclic systems and a novel technique for the alkylation of symmetrical triazoles, as a result of which model compounds were obtained in high yields. The method of intramolecular electrophilic heterocyclization was used to quaternize the nitrogen atom of the triazole heterocycle. The study of the chemical properties of the obtained salt [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium was carried out on the example of anion exchange reactions, the results of which indicate the stability of the studied cation [1,3] thiazolo[3,2-b][1,2,4]triazol-7-ium upon heating in the presence of various anions. The obtained new heterocyclic salts are promising in terms of their further study as surfactants.
 Keywords: 1,2,4-triazole; heptadecyl; [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts; surfactant.

Design of Liquid Crystal Materials Based on Palmitate, Oleate, and Linoleate Derivatives for Optoelectronic Applications

Herein, liquid crystalline derivatives based on palmitate, oleate, and linoleate moieties with azomethine cores were synthesized, and their physical, chemical, optical, and photophysical properties were investigated in detail. The mesomorphic activity of these materials was examined through polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The observed results revealed that the stability of the thermal mesophase depends on the terminal polar as well as on the fatty long-chain substituents. Purely smectogenic phases were detected in all three terminal side chains. A eutectic composition with a low melting temperature and a broad smectic A range was found by constructing a binary phase diagram and addressing it in terms of the mesomorphic temperature range. The energy bandgap of the palmitate-based derivative (Ia) was determined as 3.95 eV and slightly increased to 4.01 eV and 4.05 eV for the oleate (Ib) and linoleate (Ic) derivatives, respectively. The optical constants (n, κ, εr, and εi) were extracted from the fitting of measured spectroscopic ellipsometer data. The steady-state spectra of these samples exhibited a broad emission in the range 400-580 nm, which was found to be blue shifted to 462 nm for both Ib and Ic derivatives. The average fluorescence decay lifetime of the Ia derivative was found to be 598 ps, which became faster for the Ib and Ic derivatives and slower for the sample with a chloride end polar group.

Toughening Modification of Polylactic Acid by Long-Chain Hyperbranched Polymers Containing Polycaprolactone end Groups

The hyperbranched polyester (HBPEs) were synthesized by the "one-step method" and grafted with caprolactone (ε-Cl) to obtain long-chain hyperbranched polymers (LCHBPs-Cl). In this study, LCHBPs-Cl with Cl long chain end groups were used for the first time to toughen and strengthen polylactic acid (PLA) by melt blending. Compared with pure PLA, the most significant toughening effect was obviously when the addition amount of LCHBPs-Cl was 2.0 phr. The tensile strength increased from 37.00 to 62.61 MPa. The impact strength was increased from 14.88 to 18.50 kJ. The elongation at break increased from 1.80% to 2.50%. The scanning electron microscope (SEM) images showed the impact section of the blends became rough, the brittle-ductile fracture transition occurred, and a large number of white wire drawing phenomena were produced. Due to the formation of topological entanglement and cohesive entanglement between the long-chain substituents of LCHBPs-Cl and PLA molecular chains, the plastic deformation of PLA was successfully improved, and the toughness of polylactic acid was highly improved.

Enantioselective high-performance liquid chromatography of aryl-substituted oxazolines as an efficient tool for determination of chiral purity of serine medicinal components.

A new approach for the evaluation of chiral purity of serine esterification products bearing long-chain alkyl substituents was developed. The compounds were simply converted to aryl-substituted oxazolines which: (i) facilitates effective chromatographic enantioseparation and (ii) enables direct detection using ultraviolet absorption. The method employs a polysaccharide-based chiral stationary phase and allows enantioseparation of highly stable oxazoline products in less than 6 min using a simple binary mobile phase. As opposed to the previously used normal phase method the developed method was performed in the reversed-phase mode. Aside from the benefits of switching to less hazardous solvents with regard to the principles of Green Chemistry, this has also led to a reduction in the analysis time. In comparison with known serine chromophores, the best enantioseparation of aryloxazoline rigid structure may be achieved only based on non-polar interactions with the chiral stationary phase. In contrast, the substitution of the chromophore moiety with hydroxyl substituent affected intra and intermolecular interactions that caused enantioseparation differences. Concurrently, we found high chirality retention of (R)- and (S)-configuration oxazoline standards (≥99% enantiomeric excess) during the introduction of the ultraviolet label. The method is suitable for rapid injection of the mixture containing the ultraviolet absorption marker without prior purification.

New Cysteine-Containing PEG-Glycerolipid Increases the Bloodstream Circulation Time of Upconverting Nanoparticles.

Upconverting nanoparticles have unique spectral and photophysical properties that make them suitable for development of theranostics for imaging and treating large and deep-seated tumors. Nanoparticles based on NaYF4 crystals doped with lanthanides Yb3+ and Er3+ were obtained by the high-temperature decomposition of trifluoroacetates in oleic acid and 1-octadecene. Such particles have pronounced hydrophobic properties. Therefore, to obtain stable dispersions in aqueous media for the study of their properties in vivo and in vitro, the polyethylene glycol (PEG)-glycerolipids of various structures were obtained. To increase the circulation time of PEG-lipid coated nanoparticles in the bloodstream, long-chain substituents are needed to be attached to the glycerol backbone using ether bonds. To prevent nanoparticle aggregation, an L-cysteine-derived negatively charged carboxy group should be included in the lipid molecule.

Viscoelastic Effects of Long-Chain Acyl-Group Substituents on Molten Paramylon Mixed Esters

Viscoelastic Effects of Long-Chain Acyl-Group Substituents on Molten Paramylon Mixed Esters

Synthesis of Long-Chain Alkanoyl Benzenes by an Aluminum(III) Chloride-Catalyzed Destannylative Acylation Reaction.

This paper describes the facile synthesis of haloaryl compounds with long-chain alkanoyl substituents by the destannylative acylation of haloaryls bearing tri-n-butyltin (Bu3Sn) substituents. The method allows the synthesis of many important synthons for novel functional materials in a highly efficient manner. The halo-tri-n-butyltin benzenes are obtained by the lithium-halogen exchange of commercially available bis-haloarenes and the subsequent reaction with Bu3SnCl. Under typical Friedel-Crafts conditions, i.e., the presence of an acid chloride and AlCl3, the haloaryls are acylated through destannylation. The reactions proceed fast (<5 min) at low temperatures and thus are compatible with aromatic halogen substituents. Furthermore, the method is applicable to para-, meta-, and ortho-substitution and larger systems, as demonstrated for biphenyls. The generated tin byproducts were efficiently removed by trapping with silica/KF filtration, and most long-chain haloaryls were obtained chromatography-free. Molecular structures of several products were determined by X-ray single-crystal diffraction, and the crystal packing was investigated by mapping Hirshfeld surfaces onto individual molecules. A feasible reaction mechanism for the destannylative acylation reaction is proposed and supported through density functional theory (DFT) calculations. DFT results in combination with NMR-scale control experiments unambiguously demonstrate the importance of the tin substituent as a leaving group, which enables the acylation.

Hybrid Sol-Gel Superhydrophobic Coatings Based on Alkyl Silane-Modified Nanosilica.

Hybrid sol–gel superhydrophobic coatings based on alkyl silane-modified nanosilica were synthesized and studied. The hybrid coatings were synthesized using the classic Stöber process for producing hydrophilic silica nanoparticles (NPs) modified by the in-situ addition of long-chain alkyl silanes co-precursors in addition to the common tetraethyl orthosilicate (TEOS). It was demonstrated that the long-chain alkyl substituent silane induced a steric hindrance effect, slowing the alkylsilane self-condensation and allowing for the condensation of the TEOS to produce the silica NPs. Hence, following the formation of the silica NPs the alkylsilane reacted with the silica’s hydroxyls to yield hybrid alkyl-modified silica NPs having superhydrophobic (SH) attributes. The resulting SH coatings were characterized by contact angle goniometry, demonstrating a more than 150° water contact angle, a water sliding angle of less than 5°, and a transmittance of more than 90%. Confocal microscopy was used to analyze the micro random surface morphology of the SH surface and to indicate the parameters related to superhydrophobicity. It was found that a SH coating could be obtained when the alkyl length exceeded ten carbons, exhibiting a raspberry-like hierarchical morphology.

Effects of Long-Chain Acyl Substituents on the Thermoplasticity and Mechanical Properties of Paramylon Mixed Esters

The moldability and robustness of thermoplastic paramylon mixed esters are highly related to primary structural parameters, such as the length of the long-chain acyl group and its degree of substitution. Short chain lengths and lower substitution degrees provide more robust molded thermoplastics, whereas longer chains and higher substitution degrees improve moldability. Herein, the choice of an appropriate long-chain acyl group (lauroyl or myristoyl) and the effect of the substitution degree were investigated by examining the thermal and mechanical properties of a series of paramylon acetate laurates and myristates and comparing them with those of their curdlan analogues. Melt volume flow rate measurements (180–220 °C) indicate that myristoyl substitution in paramylon results in a local thermoplasticity maximum at a substitution degree of 0.35 at higher temperatures (above ~ 200 °C). These measurements and dynamic viscoelastic analyses suggest that the myristoyl substitution serves an “internal plasticizer” in the higher strain range and higher temperature region (~ 200–230 °C), while it serves as a “viscosity increaser” in the lower strain range and lower temperature region (170–200 °C). Moreover, tensile and bending testing showed that this product exhibits superior mechanical strength. The successful realization of a good balance between moldability and robustness suggests that fine-tuning the chain length and substitution degree is an effective approach for producing thermoplastic polysaccharides with superior injection moldabilities and mechanical robustness.

Recent Advances in the Stereoselective Total Synthesis of Natural Pyranones Having Long Side Chains.

Pyranone natural products have attracted great attention in recent years from chemists and biologists due to their fascinating stereoisomeric structural features and impressive bioactivities. A large number of stereoselective total syntheses of these compounds have been described in the literature. The natural pyranones with long side chains have recently received significant importance in the synthetic field. In the present article, we aim to review the modern progress of the stereoselective total syntheses of these natural pyranones containing long-chain substituents.

Design, synthesis and α-glucosidase inhibition study of novel embelin derivatives

Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family. It was first discovered to have potent inhibitory activity (IC50 = 4.2 μM) against α-glucosidase in this study. Then, four series of novel embelin derivatives were designed, prepared and evaluated in α-glucosidase inhibition assays. The results show that most of the embelin derivatives synthesised are effective α-glucosidase inhibitors, with IC50 values at the micromolar level, especially 10d, 12d, and 15d, the IC50 values of which are 1.8, 3.3, and 3.6 μM, respectively. Structure–activity relationship (SAR) studies suggest that hydroxyl groups in the 2/5-position of para-benzoquinone are very important, and long-chain substituents in the 3-position are highly preferred. Moreover, the inhibition mechanism and kinetics studies reveal that all of 10d, 12d, 15d, and embelin are reversible and mixed-type inhibitors. Furthermore, docking experiments were carried out to study the interactions between 10d and 15d with α-glucosidase.