Trimeric Compounds Research Articles

SrCu(OH)3Cl , an isolated equilateral triangle spin S=1/2 model system

We have investigated the magnetic ground state properties of the quantum spin trimer compound strontium hydroxy copper chloride SrCu(OH)3Cl using bulk magnetization, specific heat measurements, nuclear magnetic resonance (NMR), and electron spin resonance (ESR) spectroscopy. SrCu(OH)3Cl consists of layers with isolated Cu2+ triangles and hence provides an opportunity to understand the magnetic ground state of an isolated system of S = 1/2 arranged on an equilateral triangle. Although magnetization measurements do not exhibit a phase transition to a long-range ordered state down to T = 2 K, they reveal the characteristic behavior of isolated trimers with an exchange of J=154 K. The Curie-Weiss behavior changes around 50–80 K, as is also seen in the NMR spin-lattice relaxation rate. In zero magnetic field, our specific heat data establish a second-order phase transition to an antiferromagnetic ground state below T= 1.2 K. We have drawn a magnetic field-temperature (H−T) phase diagram based on the specific heat measurements. The ESR data show divergence of the linewidth at lower temperatures, which precedes the phase transition to an antiferromagnetic long-range ordered state with unconventional critical exponents. The temperature variation of the g-factor further confirms the antiferromagnetic phase transition and reflects the underlying magnetocrystalline anisotropy of the compound. Published by the American Physical Society 2024

Recycling Compatible Organic Electrode Materials Containing Amide Bonds for Use in Rechargeable Batteries.

Organic rechargeable batteries that do not use any scarce heavy metals are candidates for the next generation of rechargeable batteries; although, it is not easy to realize both high capacity and long cycle life. Organic compounds linked by amide bonds are expected to have superior recycling properties after battery degradation, since they will become a single monomer upon hydrolysis. In this study, anthraquinone was chosen as a model redox active unit, and dimeric and trimeric compounds were synthesized, their cycle performances as electrode materials for use in rechargeable batteries were compared, and a trend in which oligomerization improves cycle properties was confirmed. Furthermore, quantum chemistry calculations suggest that oligomerization decreases solubility, which would support a longer life for oligomerized compounds. This methodology will lead to the development of organic rechargeable batteries with further environmental benefits.

Antibiotic Potential of the Ambigol Cyanobacterial Natural Product Class and Simplified Synthetic Analogs.

The ambigols are cyanobacterial natural products characterized by three polychlorinated aromatic building blocks connected by biaryl and biaryl ether bridges. All ambigols known to date possess promising biological activities. Most significantly, ambigol A was reported to have antibacterial activity against Gram-positive bacteria, such as Bacillus megaterium and B. subtilis. We established a diverse compound library for in-depth biological evaluation building on our previous bio- and total synthetic research on this natural product family. To explore the antimicrobial potential in detail and to determine initial structure-activity relationships of this product class, a large set of dimeric and trimeric compounds were screened against selected bacterial and Candida target strains. Our results reveal exceptional antibiotic activity of the ambigols, especially against challenging clinical isolates.

Discovery and biological evaluation of a new type of dual inhibitors of indoleamine 2,3-dioxygenase 1 and tryptophan 2,3-dioxygenase from ethnomedicinal plant Dactylicapnos scandens

The root of Dactylicapnos scandens (D.Don.) Hutch (Papaveraceae), one of the most famous ethno-medicinal plants from the Bai communities in P. R. China, is used to treat various inflammations and tumours. Bioassay-guided phytochemical research on D. scandens followed by semi-synthesis led to a series of undescribed tetrahydroisoquinoline alkaloids with dual inhibitory activities against indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). The previously undescribed dark-green alkaloid dactycapnine A exhibited the best dual inhibitor effects among the identified compounds. Structure-activity relationship analysis revealed the importance of the base skeleton with a hyperconjugation system. The performed semi-synthesis further yielded bioactive dimeric and trimeric compounds with hyperconjugated systems. Performed STD NMR experiments disclosed direct interactions between dactycapnine A and IDO1/TDO. Inhibition kinetics indicated dactycapnine A as a mixed-type dual inhibitor. These findings provided a possible explanation for the anticancer properties of the ethno-medicinal plant species D. scandens.

Photophysical and anion sensing properties of a triphenylamine-dioxaborinine trimeric compound.

Herein, we report the synthesis and photophysical characterization of the novel tris(4-(2,2-difluoro-6-methyl-2H-1λ3,3,2λ4-dioxaborinin-4-yl)phenyl)amine trimeric probe (A2) via the reaction between triphenylamine (1), acetic anhydride, and BF3·OEt2 implying the twelve new bond formation in a one-pot manner. This highly fluorescent compound in solution (φ up to 0.91 at 572 nm) and solid state (φ = 0.24 at 571 nm) showed a better solvatofluorochromism than its analog monomeric A1 due to symmetry-broken charge transfer, which is consistent with high solvent dipolarity (SdP) response in Catalán's multiparametric regression. Notably, A2 had a high sensibility and selectivity for CN- or F- in solution (LODCN-/F- = 0.18/0.70 μM), and CN- can be discriminated from F- by the reaction of A2 with 3.0 equiv. of CN-. In addition, A2 was impregnated on filter paper to prepare test strips that were applied to naked-eye qualitative sensing of CN- or F-. Finally, the octupolar system in A2 allows for better action of two-photon excitation cross-section values when compared with that of the dipolar structure in A1. These findings provide further information for the design of new efficient two-photon absorption dyes.

Inhibitory Activity of Bioactive Phloroglucinols from the Rhizomes of Dryopteris crassirhizoma on Escherichia coli β-Glucuronidase: Kinetic Analysis and Molecular Docking Studies

Phloroglucinols—one of the major secondary metabolites in Dryopteris crassirhizoma—exhibit various pharmacological effects, such as antiviral, antioxidant, and antidiabetic activities. This study evaluated 30 phloroglucinols isolated from the rhizomes of D. crassirhizoma for their inhibitory activity on β-glucuronidase via in vitro assays. Among them, dimeric phloroglucinols 13–15 moderately inhibited β-glucuronidase, and trimeric phloroglucinols 26–28 showed strong inhibitory effects, with IC50 values ranging from 5.6 to 8.0 μM. Enzyme kinetic analysis confirmed all six active compounds to be in a competitive mode of inhibition. Molecular docking simulations revealed the key binding interactions with the active site of β-glucuronidase protein and the binding mechanisms of these active metabolites. Our results suggest that the rhizomes of D. crassirhizoma and trimeric compounds 26–28 may serve as potential candidates for discovering and developing new β-glucuronidase inhibitors.

Synthesis and Crystal Structures of Three Thioether Functionalized Formamidines and Their Corresponding Lithium Formamidinates

AbstractThree thioether functionalized formamidines RNHC(H)NR (R=2‐SMe‐C6H4, 2‐StBu‐C6H4, 2‐SPh‐C6H4) were prepared from the corresponding amines RNH2 and triethyl orthoformate. X‐ray crystal structure determinations revealed the typical E configuration about the amidine C=N bond for all three compounds. The 2‐SMe and 2‐StBu derivatives exhibit the most frequently observed anti orientation of the RNH group while the 2‐SPh derivative displays the much more rarely encountered syn arrangement. All three compounds exhibit weak intramolecular N−H⋅⋅⋅S hydrogen bridges of the (5) type. Treatment of the amidines with n‐BuLi led to the formation of the corresponding lithium amidinates. X‐ray crystal structure determinations of the lithium amidinates revealed several molecular patterns ranging from the mononuclear complex [Li{2‐StBu‐C6H4N)2CH}2(THF)2] to the trimeric compound [Li3{(2‐SMe‐C6H4N)2CH}3].

Development of an Improved Synthetic Process of Clonazepam by Preventing the Formation of a Trimeric Compound in the Presence of HCl

Development of an Improved Synthetic Process of Clonazepam by Preventing the Formation of a Trimeric Compound in the Presence of HCl

A predictive toolset for the identification of degradation pattern and toxic hazard estimation of multimeric hazardous compounds persists in water bodies

An array of industrial processing units generates many multimeric hazardous compounds, such as complex technical lignin and its toxic derivatives, thereby persist in expelled water bodies. The inclusion of some group of motifs in the complex technical lignin structure helps it resist degrade biologically, most often even recalcitrant. Relatively small concentrations of lignin are harmful to aquatic organisms and can trigger environmental hazards. Sadly, the entire biotransformation pathway and insightful information about these toxic derivatives are incomplete and missing in the literature. This is mainly because the current conventional treatments often fail to identify all transformed compounds and their environmental fate. Thus, a robust toolset is much needed to cover this literature gap. Inadequate performance of conventional remediation processes and biological degradation patterns can be maximally optimized with the aid of predictive toolset methods that could offer better degradability and complete transformed compound information. A predictive toolset-assisted biodegradation pattern determination is a multifaceted and reliable analytical technique that can help to overcome existing shortcomings by providing an entire transformation pathway. Considering the above critiques, this work reports on the degradation pattern, and toxicological endpoints of five hazardous compounds, i.e., 2-chlorosyringaldehyde, 5-chlorovanillin, catechol, guaiacyl 4-O-5 guaiacyl, and syringyl β-O-4 syringyl β-O-4 sinapyl alcohol, that persists in water matrices. The predictive transformation pattern was revealed notably less complex end-products of catechol as; succinate, and 2-Oxo-4-pentenoate. The gastrointestinal (GI) absorption rate was found high for all tested compounds, excluding trimer compound, i.e., syringyl β-O-4 syringyl β-O-4 sinapyl alcohol. The toxicity and persistence profile tested via Toxtree showed that the Cramer Rules, Verhaar Scheme, and Structural Alerts for Reactivity, (START) biodegradation ability as positive, and all five target compounds were found as class-II persistent compounds. Furthermore, the Ecological Structure-Activity Relationships (ECOSAR)assisted testing specifies that all tested derivatives have multiple aquatic toxic levels. In summary, the current findings endorse the hazardous compounds and undertake prescreening of the deprivation policy to protect the environment.

Identification of Phytochemicals from the Water Extract of Eurycoma longifolia Roots using Solid-Liquid and Liquid-Liquid Extraction Based Fractionation Techniques.

Phytochemicals in the water extract of Eurycoma longofolia roots were identified using both solid-liquid and liquid-liquid extraction based fractionation techniques. A reversed phase C18 solid phase extraction (SPE) was used as solid-liquid extraction, whereas solvent partition was applied as liquid-liquid extraction. Total saponin was increased after fractionation. A few known quassinoids; eurycomanone, 13a(21)-epoxyeurycomanone, pasakbumin D, 13β,18-dihydroeurycomanol and 13β,21-dihydroxyeurycomanol were identified from the 40% and 60% methanol fractions of SPE. Solvent partition extract using ethyl acetate was found to have the highest saponin content compared to butanol and chloroform fractions. Subsequent acetone precipitation of the organic fractions recovered a formylated hexose trimer and other saccharide-containing compounds. Ethyl acetate effectively recovered saponins from E. longofolia water extract using liquid-liquid extraction followed by acetone precipitation.

Biomimetic Synthesis of Lavandiolides H, I, and K and Artematrolide F via Diels-Alder Reaction.

The biomimetic synthesis of guaianolide dimers lavandiolides H, I, and K and artematrolide F containing a spirolactone moiety has been accomplished for the first time from naturally abundant arglabin in four to six steps with an overall yield up to 60%, and a series of natural product-like guaianolide dimers, trimer, and tetramer were also successfully synthesized. Notably, the trimeric compound exhibited antihepatoma cytotoxicity more potent than that of sorafenib with IC50 values of 6.2 μM (HepG2), 6.8 μM (Huh7), and 7.2 μM (SK-HEP-1).

Exploration of stilbenoid trimers as potential inhibitors of sirtuin1 enzyme using a molecular docking and molecular dynamics simulation approach.

A combination of molecular docking and molecular dynamics simulation (250 ns) has been carried out to study the interaction of stilbenoid trimer compounds with the SIRT1 enzyme as the target protein. SIRT1 expression regulates cellular stress responses that lead to the development of cancer. Redocking showed a good native ligand pose with an RMSD value of 1.40 Å at the receptor active site's coordinates. The molecular docking score uses a grid score functional (kcal mol−1), which shows results of 1NS: 79.56, TS1: −26.83, TS2: −87.77, and TS3: −83.67. The TS2 and TS3 candidates were chosen for further analysis because they had a lower grid score than the native ligand (1NS). Furthermore, prediction of binding free energy (kcal mol−1) using the Quantum Mechanics/generalized Born Surface Area (QM/MM-GBSA) method shows the results of 1NS: −31.52 ± 0.39, TS2: −58.99 ± 0.34, and TS3: −43.38 ± 0.35. These results indicate that the TS2 and TS3 compounds have good potential as inhibitors of the SIRT1 enzyme. Additionally, the amino acid residues were responsible for the inhibition mechanism through hydrogen bond interactions at the molecular level, including ASP22, PHE91, PRO11, ILE165, ASP166, and VAL230. The observations made in this study provide theoretical information for exploring the stilbenoid trimers as anticancer agents by targeting the SIRT1 enzyme.

Understand the Specific Regio- and Enantioselectivity of Fluostatin Conjugation in the Post-Biosynthesis.

Fluostatins, benzofluorene-containing aromatic polyketides in the atypical angucycline family, conjugate into dimeric and even trimeric compounds in the post-biosynthesis. The formation of the C–C bond involves a non-enzymatic stereospecific coupling reaction. In this work, the unusual regio- and enantioselectivities were rationalized by density functional theory calculations with the M06-2X (SMD, water)/6–311 + G(d,p)//6–31G(d) method. These DFT calculations reproduce the lowest energy C1-(R)-C10′-(S) coupling pathway observed in a nonenzymatic reaction. Bonding of the reactive carbon atoms (C1 and C10′) of the two reactant molecules maximizes the HOMO–LUMO interactions and Fukui function involving the highest occupied molecular orbital (HOMO) of nucleophile p-QM and lowest unoccupied molecular orbital (LUMO) of electrophile FST2− anion. In particular, the significant π–π stacking interactions of the low-energy pre-reaction state are retained in the lowest energy pathway for C–C coupling. The distortion/interaction–activation strain analysis indicates that the transition state (TScp-I) of the lowest energy pathway involves the highest stabilizing interactions and small distortion among all possible C–C coupling reactions. One of the two chiral centers generated in this step is lost upon aromatization of the phenol ring in the final difluostatin products. Thus, the π–π stacking interactions between the fluostatin 6-5-6 aromatic ring system play a critical role in the stereoselectivity of the nonenzymatic fluostatin conjugation.

Tricarabrols A–C, three anti-inflammatory sesquiterpene lactone trimers featuring a methylene-tethered linkage from Carpesium faberi

Three anti-inflammatory trimeric compounds constructed from carabrol-type sesquiterpenoids through a methylene-tethered linkage were characterized from Carpesium faberi.

Selective molecular separation of lignin model compounds by reduced graphene oxide membranes from solvent-water mixture

Selective separation of lignin depolymerization products is key to fractionating and isolating high-value aromatic compounds from the depolymerization process. The primary aim of this study was to synthesis graphene oxide (GO) membranes for selective separations of lignin oligomeric units from polar organic solvent-water media. GO membranes were synthesized on a polymeric substrate by a shear assisted casting of aqueous GO dispersion using a wire-wound rod. Deposited GO was then reduced to different extents by controlled thermal incubation, and the impact on membrane performance was investigated. The extent of reduction of GO was established by extensive characterization with FTIR, XPS, Raman Spectroscopy, XRD, and contact angle measurements. Impressive performance with the rejection of over 70% for the model compound trimer BMP (2,6-bis[(2-hydroxy-5-methyl phenyl) methyl]-4-methylphenol) was achieved compared to only 20% rejection for the dimer GGE (guaiacylglycerol-β-guaiacylether) with isopropanol-water (90–10% by volume) as a solvent. This corresponds to an encouraging selective separation with selective permeation of dimer (GGE) 3.5 times higher compared to trimer (BMP). rGO membranes exhibited a stable performance over 84 h of operation at a shear rate of 1.1 Pa in a cross-flow mode of operation. Selective separation of GO can be effectively modulated by controlling the O/C ratio by the extent of reduction of GO; indeed, the retention of trimeric compounds increased with increasing GO reduction. The remarkable performance of GO membranes could enable energy-efficient fractionation of lignin oligomeric compounds from polar organic solvents.

Effects of Epigallocatechin Gallate on the Stability of Epicatechin in a Photolytic Process.

Catechins belonging to polyhydroxylated polyphenols are the primary compounds found in green tea. They are associated with many physiological properties. Epicatechin (EC) is a non-gallate-type catechin with four phenolic hydroxyl groups attached. The changes in EC treated with color light illumination in an alkaline condition were investigated by chromatographic and mass analyses in this study. In particular, the superoxide anion radical (O2•−) was investigated during the EC photolytic process. EC is unstable under blue light illumination in an alkaline solution. When EC was treated with blue light illumination in an alkaline solution, O2•− was found to occur via a photosensitive redox reaction. In addition, the generation of monomeric, dimeric, and trimeric compounds is investigated. On the other hand, epigallocatechin gallate (EGCG), which is a gallate-type catechin, is stable under blue light illumination in an alkaline solution. Adding EGCG, during the blue light illumination treatment of EC decreased photolytic formation, suggesting that gallate-type catechins can suppress the photosensitive oxidation of EC. Gallate-type catechins are formed via the esterification of non-gallate-type catechins and gallic acid (GA). The carbonyl group on the gallate moiety of gallate-type catechins appears to exhibit its effect on the stability against the photosensitive oxidation caused by blue light illumination.

Trimer-based spin liquid candidate Ba4NbIr3O12

Ba4NbIr3O12, a previously unreported material with a triangular planar geometry of Ir3O12 trimers, is described. Magnetic susceptibility measurements show no magnetic ordering down to 1.8 K despite the Curie-Weiss temperature of -13 K. The material has a very low effective magnetic moment of 0.80 {\mu}B/f.u. To look at the lower temperature behavior, the specific heat (Cp) was measured down to 0.35 K; it shows no indication of magnetic ordering and fitting a power law to Cp vs. T below 2 K yields the power {\alpha} = 3/4. Comparison to the previously unreported trimer compound made with the 4d element Rh in place of the 5d element Ir, Ba4NbRh3O12, is presented. The analysis suggests that Ba4NbIr3O12 is a candidate spin liquid material.

In situ Monitoring of the Formation of [Bis(acetylacetonato)manganese(II)] Complexes

[Bis(acetylacetonato)manganese(II)] complexes are important precursors for the synthesis of catalytic MnO nanoparticles. However, the mechanism of the formation of these materials still remains unknown. In this work, a combination of ex situ and synchrotron‐based in situ powder X‐ray diffraction with in situ pH, conductivity, and turbidity measurements was applied to investigate the concentration‐dependent formation of [Mn(acac)2(H2O)2]; interestingly [Mn(acac)2(H2O)2] undergoes an expansion of the unit cell during the synthesis as well as upon heating. Increasing the temperature to 80 °C caused the conversion of solid [Mn(acac)2(H2O)2] to the trimer compound [Mn(acac)2]3, which occurs ex situ (in solid state), but is hindered in solution. [Mn(acac)2(H2O)2] emits light in the blue‐green spectral range with emission maximum at 520 nm, measured in situ under real reaction conditions during its formation due to the instability of this compound.

FeII Complexes with Triple N1,N2‐Triazole Bridge Schiff Base Ligand: Antiferromagnetic Dimer vs. Spin Conversion Trimer

Based on the p‐tolyl functionalized Schiff base 1,2,4‐triazole ligand 4‐(p‐tolylidene‐amino)‐4H‐1,2,4‐triazole (toltrz), a series of three triazole‐bridged FeII complexes have been prepared. The compounds represent a range of dinuclear and trinuclear species, with µ2‐N1,N2‐triazole bridges linking the FeII centers. Mössbauer spectroscopy and magnetic susceptibility measurements reveal a gradual single‐step spin crossover (SCO) behavior for the trimeric compound 3 on the central FeII site. Single‐crystal X‐ray diffraction at 120 K confirms that the central FeII site undergoes a HS to LS transition while the peripheral FeII remain in HS state (HS = high spin; LS = low spin). Compounds 1 and 2 are isostructures with different terminal ligand XCN (X = S, Se), these two compounds stay in high spin state over the whole temperature range but display weak antiferromagnetic exchange coupling.

Synthesis of epigallocatechin trimer, (epigallocatechin)2-epicatechin, and (epigallocatechin)2-catechin via a Lewis acid mediated one-pot condensation and their antitumor activities in prostate cancer cells

Syntheses of epigallocatechin trimer, (epigallocatechin)2-epicatechin and (epigallocatechin)2-catechin were achieved. The key condensation to form the proanthocyanidin trimer derivatives was accomplished in a one-pot procedure using a dimeric epigallocatechin electrophile, which was prepared in situ by self-condensation of an epigallocatechin derivative, and an epigallocatechin, epicatechin, or catechin derivative as the nucleophile in the presence of a Lewis acid. The epigallocatechin monomer to trimer compounds containing a pyrogallol group significantly suppressed cell proliferation in PC-3 prostate cancer cells.