Cyclic Compounds Research Articles

Unveiling the influence of end-capped acceptors modification on photovoltaic properties of non-fullerene fused ring compounds: a DFT/TD-DFT study.

Herein, unique A-D-A configuration-based molecules (NBD1-NBD7) were designed from the reference compound (NBR) by utilizing the end-capped acceptor modification approach. Various electron-withdrawing units -F, -Cl, -CN, -NO2, -CF3, -HSO3, and -COOCH3, were incorporated into terminals of reference compound to designed NBD1-NBD7, respectively. A theoretical investigation employing the density functional theory (DFT) and time-dependent DFT (TD-DFT) was performed at B3LYP/6-311G(d,p) level. To reveal diverse opto-electronic and photovoltaic properties, the frontier molecular orbitals (FMOs), absorption maxima (λ max), density of states (DOS), exciton binding energy (E b), open-circuit voltage (V oc) and transition density matrix (TDM) analyses were executed at the same functional. Moreover, the global reactivity parameters (GRPs) were calculated using the HOMO-LUMO energy gaps from the FMOs. Significant results were obtained for the designed molecules (NBD1-NBD7) as compared to NBR. They showed lesser energy band gaps (2.024-2.157 eV) as compared to the NBR reference (2.147 eV). The tailored molecules also demonstrated bathochromic shifts in the chloroform (671.087-717.164 nm) and gas phases (623.251-653.404 nm) as compared to NBR compound (674.189 and 626.178 nm, respectively). From the photovoltaic perspectives, they showed promising results (2.024-2.157 V). Furthermore, the existence of intramolecular charge transfer (ICT) in the designed compounds was depicted via their DOS and TDM graphical plots. Among all the investigated molecules, NBD4 was disclosed as the excellent candidate for solar cell applications owing to its favorable properties such as the least band gap (2.024 eV), red-shifted λ max in the chloroform (717.164 nm) and gas (653.404 nm) phases as well as the minimal E b (0.126 eV). This is due to the presence of highly electronegative -NO2 unit at the terminal of electron withdrawing acceptor moiety, which leads to increased conjugation and enhanced the intramolecular charge transfer (ICT) rate. The obtained insights suggested that the designed molecules could be considered as promising materials for potential applications in the realm of OSCs.

Polyoxometalate Functionalized Cyclic Trinuclear Copper Compounds for Bifunctional Electrochemical Detection and Photocatalytic Reduction of Cr(VI).

The design and intentional construction of crystalline materials containing two clusters with redox properties in one framework still remains challenging. Linking oxidative polyoxometalate (POM) clusters and a reductive cyclic trinuclear copper complex (Cu-CTC) to prepare stable catalysts is rarely reported. Herein, we successfully obtained two new polyoxometalate-based metal-organic compounds (POMOCs) [CuII3(PyCA)3(μ3-OH)(β-Mo8O26)0.5(H2O)2]·5H2O (1), [CuII3(PyCA)3(μ3-OH)]2(CuIIW12O40)[CuII(H2O)6] (2) (PyCA = 1H-pyrazole-4-carbaldehyde) by enabling precursors of Cu-CTC and POM cocrystallization in one pot via hydrothermal method. The [β-Mo8O26]4- cluster in compound 1 combined with Cu-CTC units to form a 1D structure, and the [CuW12O40]6- unit in compound 2 linked two Cu-CTC units to form a sandwich-like 0D structure. Also, Cu-CTC CuI3(PyCA)3·H2O (Cu3) was synthesized for performance comparison. A series of characterizations indicate that compound 1 is more conducive to electron transfer than compound 2. In addition, compounds 1 and 2 can act as bifunctional catalysts for the electrochemical detection and photocatalytic reduction of Cr(VI). Particularly, the photoreduction rates of Cr(VI) by compounds 1 and 2 are 96.7% and 96.3% for only 10 and 14 min under visible light, respectively, and it is better than that of Cu3 and most other reported photocatalysts. Furthermore, the active sites and mechanisms for electrochemical detection and photocatalytic reduction of Cr(VI) were discussed.

Kinetics of direct and water‐mediated tautomerization reactions of four‐membered cyclic lactims to amides or lactams

AbstractAs part of a series of studies of hydrogen‐atom transfer or tautomerization reactions of imidic acid‐amide species, ──═─ ═──, we report the rate constants for a set of 16 four‐membered cyclic compounds at low, 50–300 K, and high, 500–1500 K, temperatures. The compounds are labeled according to the two ring groups X and Y, which can be , NH, CH, N, O, or C(O) and which are at some remove from the reactive site. These rate constants are for both the direct reaction and for that mediated by an additional water molecule, which facilitates the hydrogen transfer reaction. In the latter case, we show that the rate of reaction from a pre‐reaction complex is rapid at temperatures down to 50 K and dominated by quantum mechanical effects as evaluated by small‐curvature and quantized‐reaction‐states tunneling. In addition, we present thermochemical data such as enthalpies of formation, entropies, isobaric heat capacities, and enthalpy functions for these largely unknown species, which span a range of compounds from ‐propiolactone to 1,3‐diazetidine‐2,4‐dione.

An Intramolecular-Lock Facilitates Planar Tricyclic Fused Energetic Compounds.

Exploiting novel fused cyclic frameworks through simple and efficient methods has provided a blueprint for developing advanced explosives. In this study, six new [5,6,5]-tricyclic fused energetic compounds (I-VI) were synthesized through an intramolecular cyclization strategy involving a C-NH2 directed cyclization reaction. The work not only boosts the development of fused cyclic energetic compounds but also highlights their potential applications as secondary or heat-resistant explosives.

Density Function Theory Study on the Energy and Circular Dichroism Spectrum for Methylene-Linked Triazole Diads Depending on the Substitution Position and Conformation.

Since the discovery of metal-catalyzed azide-alkyne cycloadditions, 1,2,3-triazoles have been widely used as linkers for various residues. 1,2,3-Triazole is an aromatic five-membered cyclic compound consisting of three nitrogen and two carbon atoms with large dipoles that absorb UV light. In the past decade, we have been working on the synthesis of dense triazole polymers possessing many 1,2,3-triazole residues linked through a carbon atom in their backbone as a new type of functional polymer. Recently, we reported that stereoregular dense triazole uniform oligomers exhibit a circular dichroism signal based on the chiral arrangement of two neighboring 1,2,3-triazole residues. In this study, to investigate the chiral conformation of two neighboring 1,2,3-triazole residues in stereoregular dense triazole uniform oligomers, density functional theory (DFT) calculations were performed using 1,2,3-triazole diads with different substitution positions and conformations as model compounds and compared with our previous results.

Theoretical Prediction and Comprehensive Characterization of an All-Nitrogenatomic Ring, Cyclo[18]Nitrogen (N18).

The cyclic molecule cyclo[18]carbon composed of 18 carbon atoms has been observed in condensed phase experiment in recent years and has attracted great attention. Through state-of-art quantum chemistry calculation, this study found that 18 nitrogen atoms can also form a macrocyclic system, cyclo[18]nitrogen (N18), though its lifetime is very short at room temperature and can only exist for a relatively long time at very low temperatures. We comprehensively theoretically studied properties of N18, including geometric configurations, thermal decomposition mechanism and rate, molecular dynamics behavior, energetic properties, vibrational and electronic spectra. We also discussed in depth the electronic structure of N18, including nature of the N-N bonds, lone-pairs, charge distribution characteristics, electronic delocalization, and aromaticity. This work is not only the first exploration of the macrocyclic N18 molecule, but also the first time to systematically examine a very long-chain substance fully composed of nitrogen atoms in isolated state.

Comparison of volatile compound profiles derived from various livestock protein alternatives including edible-insect, and plant-based proteins

In this study, the distinctive chemical fingerprints that contribute to the flavor characteristics of various protein materials, such as insects, plant-based protein, and livestock, were investigated. In edible-insects (Tenebrio molitor and Protaetia brevitarsis), aldehydes and cyclic volatile compounds were the predominant volatile components and had distinct flavor characteristics such as cheesy, sharp, green, floral, and sweet. In contrast, the relatively high levels of pyrazines and furans in plant-based protein materials, such as textured vegetable and pea protein. They included unique flavor properties characterized by sweet, fatty, grassy, creamy, and roasted. The primary volatile chemical group detected in livestock protein materials, such as a pork and a beef, was ketones. The pork sample showed specific flavors, such as alcoholic, green, and fruity, while a beef presented distinctive flavor, including creamy, fruity, and alcoholic. Based on the results, this research provided the understanding of the flavor aspects of diverse protein materials.

Cyclization via Metal-Catalyzed Hydrogen Atom Transfer/Radical-Polar Crossover

AbstractCatalytic transformations of alkenes via the metal-hydride hydrogen atom transfer (MHAT) mechanism have notably advanced synthetic organic chemistry. This Account focuses on MHAT/radical-polar crossover (MHAT/RPC) conditions, offering a novel perspective on generating electrophilic intermediates and facilitating various intramolecular reactions. On using cobalt hydrides, the MHAT mechanism displays exceptional chemoselectivity and functional group tolerance, making it invaluable for the construction of complex biologically relevant molecules under mild conditions. Recent developments have enhanced regioselectivity and expanded the scope of MHAT-type reactions, enabling the formation of cyclic molecules via hydroalkoxylation, hydroacyloxylation, and hydroamination. Notably, the addition of an oxidant to traditional MHAT systems enables the synthesis of rare cationic alkylcobalt(IV) complexes, bridging radical mechanisms to ionic reaction systems. This Account culminates with examples of natural product syntheses and an exploration of asymmetric intramolecular hydroalkoxylations, highlighting the ongoing challenges and opportunities for future research to achieve higher enantioselectivity. This comprehensive study revisits the historical evolution of the MHAT mechanism and provides a groundwork for further innovations on the synthesis of structurally diverse and complex natural products.1 Introduction2 Intramolecular Hydroalkoxylation and Hydroacyloxylation Reactions3 Intramolecular Hydroamination Reactions4 Intramolecular Hydroarylation Reactions5 Deprotective Cyclization6 Asymmetric Intramolecular Hydroalkoxylation7 Conclusion

Avellanin A Has an Antiproliferative Effect on TP-Induced RWPE-1 Cells via the PI3K-Akt Signalling Pathway.

Cyclic pentapeptide compounds have garnered much attention as a drug discovery resource. This study focused on the characterization and anti-benign prostatic hyperplasia (BPH) properties of avellanin A from Aspergillus fumigatus fungus in marine sediment samples collected in the Beibu Gulf of Guangxi Province in China. The antiproliferative effect and molecular mechanism of avellanin A were explored in testosterone propionate (TP)-induced RWPE-1 cells. The transcriptome results showed that avellanin A significantly blocked the ECM-receptor interaction and suppressed the downstream PI3K-Akt signalling pathway. Molecular docking revealed that avellanin A has a good affinity for the cathepsin L protein, which is involved in the terminal degradation of extracellular matrix components. Subsequently, qRT-PCR analysis revealed that the expression of the genes COL1A1, COL1A2, COL5A2, COL6A3, MMP2, MMP9, ITGA2, and ITGB3 was significantly downregulated after avellanin A intervention. The Western blot results also confirmed that it not only reduced ITGB3 and FAK/p-FAK protein expression but also inhibited PI3K/p-PI3K and Akt/p-Akt protein expression in the PI3K-Akt signalling pathway. Furthermore, avellanin A downregulated Cyclin D1 protein expression and upregulated Bax, p21WAF1/Cip1, and p53 proapoptotic protein expression in TP-induced RWPE-1 cells, leading to cell cycle arrest and inhibition of cell proliferation. The results of this study support the use of avellanin A as a potential new drug for the treatment of BPH.

Oligoester Identification in the Inner Coatings of Metallic Cans by High-Pressure Liquid Chromatography-Mass Spectrometry with Cone Voltage-Induced Fragmentation.

The application of polyesters as food contact materials is an alternative to epoxy resin coatings, which can be a source of endocrine migrants. By using high-pressure liquid chromatography/electrospray ionization-mass spectrometry (HPLC/ESI-MS) with cone voltage-induced fragmentation in-source, a number of polyester-derived migrants were detected in the extracts of inner coatings of metallic cans. The polyester-derived migrants were detected in each inner coating of fish product-containing cans (5/5) and in one inner coating of meat product-containing can (1/5). They were not detected in the inner coatings of vegetable/fruit product-containing cans (10 samples). The respective detected parent and product ions enabled differentiation between cyclic and linear compounds, as well as unambiguous identification of diol and diacid units. Most of the detected compounds, cyclic and linear, were composed of neopentyl glycol as diol and two diacid comonomers, namely isophthalic acid and hexahydrophthalic acid. The other detected oligoesters were composed of neopentyl glycol or propylene glycol and adipic acid/isophthalic acid as comonomers. The compounds containing propylene glycol as diol were found to be exclusively linear cooligoesters. On the basis of abundances of [M+Na]+ ions, the relative contents of cyclic and linear oligoesters were evaluated.

Genotyping-by-Sequencing Analysis Reveals Associations between Agronomic and Oil Traits in Gamma Ray-Derived Mutant Rapeseed (Brassica napus L.).

Rapeseed (Brassica napus L.) holds significant commercial value as one of the leading oil crops, with its agronomic features and oil quality being crucial determinants. In this investigation, 73,226 single nucleotide polymorphisms (SNPs) across 95 rapeseed mutant lines induced by gamma rays, alongside the original cultivar ('Tamra'), using genotyping-by-sequencing (GBS) analysis were examined. This study encompassed gene ontology (GO) analysis and a genomewide association study (GWAS), thereby concentrating on agronomic traits (e.g., plant height, ear length, thousand-seed weight, and seed yield) and oil traits (including fatty acid composition and crude fat content). The GO analysis unveiled a multitude of genes with SNP variations associated with cellular processes, intracellular anatomical structures, and organic cyclic compound binding. Through GWAS, we detected 320 significant SNPs linked to both agronomic (104 SNPs) and oil traits (216 SNPs). Notably, two novel candidate genes, Bna.A05p02350D (SFGH) and Bna.C02p22490D (MDN1), are implicated in thousand-seed weight regulation. Additionally, Bna.C03p14350D (EXO70) and Bna.A09p05630D (PI4Kα1) emerged as novel candidate genes associated with erucic acid and crude fat content, respectively. These findings carry implications for identifying superior genotypes for the development of new cultivars. Association studies offer a cost-effective means of screening mutants and selecting elite rapeseed breeding lines, thereby enhancing the commercial viability of this pivotal oil crop.

The preparation of hollow graphene microspheres and its application research in environmental management

In this study, hollow graphene microspheres (GO-GE) were prepared using Gemini surfactants as hydrophobic modifiers by direct mixing method. By changing the amount of Gemini surfactants, hollow graphene microspheres with different surfactant/graphene ratios were obtained. Aromatic cyclic compounds were used as simulated pollutants to investigate the adsorption capacity of hollow graphene microspheres for simulated wastewater. The results showed that the amount of surfactant had a significant effect on the particle size, density, and hydrophilic properties of the hollow graphene microspheres. When the amount of Gemini surfactants increased, the hydrophobicity of GE-GO hollow graphene microspheres improved, and the adsorption of hydrophobic pollutants such as aromatic cyclic compounds was faster and more effective. The removal rates of toluene and benzene were as high as 84.7% and 92.6%, respectively. The order of removal rates for aromatic cyclic compounds was toluene > benzene > 4-nitrophenol > 4-nitroaniline > methyl red > methylene blue. The obtained microspheres had a long-term stability in solution, which could avoid re-polluting the water body. In addition, repeated experiments demonstrated that the microspheres had good reusability. Therefore, this type of hollow graphene microspheres may have great potential application prospects in the field of environmental wastewater treatment.

Thermal Conductivity of Liquid Cyclohexane, n-Decane, n-Hexadecane, and Squalane at Atmospheric Pressure up to 353 K Determined with a Steady-State Parallel-Plate Instrument

The present work reports experimental data on the thermal conductivity of the four hydrocarbons cyclohexane, n-decane, n-hexadecane, and squalane in the liquid state at ambient pressure up to temperatures of 353.15 K. Absolute measurements were performed with a steady-state guarded parallel-plate instrument (GPPI) with an average expanded (coverage factor k = 2) measurement uncertainty of 2 %. For the linear alkanes n-decane and n-hexadecane as well as the cyclic compound cyclohexane, the measured thermal conductivities agree with reference correlations in the literature, indicating the reliability of the technique used for the study of fluids with relatively low thermal conductivities and weak absorption of radiation. For the first time, experimental data are determined for the long-branched alkane squalane between (278 and 353) K, which cannot be accurately represented with estimation methods commonly used in the literature. In summary, the present measurement results confirm the existing database for representative linear and cyclic hydrocarbons and provide first experimental thermal conductivities for squalane.

Post-synthetic modification of near-infrared absorbing cyclodextrin-encapsulated cyanine dyes for controlling absorption wavelength, stability, and singlet oxygen generation

Abstract In this study, near-infrared absorbing rotaxane-type cyanine dyes exhibit high tolerance to various chemical reactions, which is attributed to the encapsulation effect of their cyclic molecules. As a result, rotaxane dyes can be post-modified on the host α-cyclodextrin or guest cyanine skeleton to adjust their solubility, absorption wavelength, stability, and singlet oxygen generation ability. The guest modification product obtained via the Heck reaction demonstrates a red shift of its absorption wavelength owing to the extended conjugation system. Moreover, the products of host modification through the methylation and benzylation of all cyclodextrin hydroxyl groups not only become lipophilic and show extended absorption, but also exhibit higher photooxidation tolerance, lower singlet oxygen generation rate, and increased singlet oxygen tolerance, indicating their potential applicability as highly durable dyes. Furthermore, the outstanding singlet oxygen tolerance of these dyes enables their use in long-life singlet oxygen generators, in which the total amount of singlet oxygen increases. This work demonstrates that an intrinsically unstable near-infrared cyanine dye can be used as a synthetic intermediate by stabilizing it via α-cyclodextrin encapsulation, allowing the post-modification of various properties of cyanine dyes toward the higher-order near-infrared-absorbing materials with complex functionalities and diverse utilities.

Structural and functional characterization of the bacterial Cap3 enzyme in deconjugation and regulation of the cyclic dinucleotide transferase CD-NTase

The Cyclic GMP-AMP synthase (cGAS) and cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzymes belong to the key components of the innate immune sensor system that generates cyclic dinucleotide molecules in response to danger signals. Recently, it was discovered that CD-NTase in bacteria can undergo conjugation to protein substrates via an E1/E2 enzyme-mediated process, resembling ubiquitin modification system. Subsequently, these CD-NTase conjugated molecules will be hydrolyzed by the Cap3 enzyme in the same gene cluster. However, the experimental structure of bacterial CD-NTase recognized by Cap3 is unknown. Here, we first determined the crystal structure of the Cap3 enzyme in complex with the C-terminal tail of CD-NTase. Our structural and enzymatic analysis revealed that the C-terminal tail of CD-NTase is both necessary and sufficient for the Cap3-mediated hydrolysis of CD-NTase from its substrates. Interestingly, we further observed that after the hydrolysis reaction, the terminal glycine residue of the CD-NTase C-terminal tail was sequentially removed by Cap3, indicating that Cap3 might play a role in quenching the CD-NTase conjugation reaction. Our work provides experimental evidence elucidating the interaction between Cap3 and CD-NTase, and suggests a potential role for Cap3 in the bacterial Cyclic-oligonucleotide-based anti-phage signaling system (CBASS).

Beyond 1,2,3-triazoles: Formation and Applications of Ketemines Derived from Copper Catalyzed Azide Alkyne Cycloaddition.

Ketemines represent an interesting class of organic intermediates that has undergone a regrowth as a consequence of recent extensions of copper catalyzed azide alkyne cycloaddition (Cu- AAC) to other synthetic fields. This review summarizes the most recent generation methods of ketimines from CuAAC reaction, highlighting chemical properties focused on the synthesis of cyclic compounds, among others, affording a general outlook towards the development of new biologically active compounds.

A theoretical study of the photochemistry of 1,3-cyclopentadiene and its cyano derivatives bound to a water dimer: Assessing reactivity of ionized clusters and possible photoproducts

We theoretically investigate the photoionization scenarios of molecular complexes involving cyclopentadiene and cyanocyclopentadiene bound to water dimers. Using electronic structure calculations within density-functional theory (DFT) and time dependent DFT (TD-DFT), we explore the potential photochemical pathways following ionization, and determine the charge transfer excitations related to the possible subsequent reactions. Our findings suggest that the investigated photochemical pathways of the hydrated complexes take place in two well-defined ultraviolet regions: (i) 8.2–9.5 eV for the cyclic compounds and (ii) 11.2–11.4 eV for the bound water dimer. We quantify how H-bonding effects can influence the photoionization channels. Before forming possible photoproducts, we also examine the regiospecificity of OH addition to 1,3-cyclopentadiene and its cyano derivatives We analyze our results in light of photoionization studies of jet-cooled molecular complexes and possible implications in astrochemical environments.

Design,Synthesis, and Molecular Docking Study of Some New Tris-Hetero Cyclic Compounds( Pyridyl, 1, 3, 4-Oxadiazole, and 1,3- Oxazepine ) as Possible Antimicrobial Agent

Design,Synthesis, and Molecular Docking Study of Some New Tris-Hetero Cyclic Compounds( Pyridyl, 1, 3, 4-Oxadiazole, and 1,3- Oxazepine ) as Possible Antimicrobial Agent

Psammaplin A analogues with modified disulfide bond targeting histone deacetylases: Synthesis and biological evaluation

Psammaplin A (PsA), a symmetrical bromotyrosine-derived disulfide marine metabolite, has been reported could inhibit HDAC1/2/3 through its thiol monomer. Inspired by the disuflide bond structure of this marine natural product, we designed and synthesized a series of PsA analogues, in which the disulfide bond of PsA was replaced with diselenide bond or cyclic disulfide/diselenide/selenenylsulfide motifs. We also studied the HDAC inhibition, cell growth inhibition, and apoptosis induction of these PsA analogues. The results showed that, all the synthetic diselenide analogues and cyclic selenenyl sulfide compounds exhibited better antiproferative activity than their counterpart of disulfide analogues. Among the prepared analogues, diselenide analogue P-503 and P-116 significantly increased the ability of inhibiting HDAC6 and induced apoptosis and G2/M cell cycle arrest. However, cyclic selenenylsulfides analogues P-111 lost its HDAC inhibitory ability and exhibited no effect on cell cycle and apoptosis, indicating that the anti-proliferative mechanism of cyclic selenenylsulfides analogues has changed.

Synthesis and structural characterization of new macrocyclic inhibitors of the Zika virus NS2B-NS3 protease.

Three new series of macrocyclic active site-directed inhibitors of the Zika virus (ZIKV) NS2B-NS3 protease were synthesized. First, attempts were made to replace the basic P3 lysine residue of our previously described inhibitors with uncharged and more hydrophobic residues. This provided numerous compounds with inhibition constants between 30 and 50 nM. A stronger reduction of the inhibitory potency was observed when the P2 lysine was replaced by neutral residues, all of these inhibitors possess Ki values >1 µM. However, it is possible to replace the P2 lysine with the less basic 3-aminomethylphenylalanine, which provides a similarly potent inhibitor of the ZIKV protease (Ki = 2.69 nM). Crystal structure investigations showed that the P2 benzylamine structure forms comparable interactions with the protease as lysine. Twelve additional structures of these inhibitors in complex with the protease were determined, which explain many, but not all, SAR data obtained in this study. All individual modifications in the P2 or P3 position resulted in inhibitors with low antiviral efficacy in cell culture. Therefore, a third inhibitor series with combined modifications was synthesized; all of them contain a more hydrophobicd-cyclohexylalanine in the linker segment. At a concentration of 40 µM, two of these compounds possess similar antiviral potency as ribavirin at 100 µM. Due to their reliable crystallization in complex with the ZIKV protease, these cyclic compounds are very well suited for a rational structure-based development of improved inhibitors.