Polymerization of isoprene, myrcene, and butadiene catalyzed by cobalt complexes supported with 2‐acetyl‐6‐iminopyridine ligand

Posted on 8 September 2023 by nJingyu You, nBinghui Chen, nDirong Gongn

2-Acetyl-6-iminopyridine ligand-supported cobalt catalyst is highly active in isoprene, myrcene, and butadiene catalytic polymerization. The catalytic performances are stable against temperature, cocatalyst feeding, and monomer ratio.

Cobalt complexes carrying 2-acetyl-6-iminopyridine ligand are synthesized and characterized. Single-crystal X-ray diffraction reveals the cobalt ion is chelated with two nitrogen atoms and an acetyl oxygen atom additionally. A significant prolonged Co–O distance (2.3960(57) Å) is found, indicative of a labile character. Activated by diethylchloroaluminum, all complexes show high conversion rates for isoprene and myrcene polymerizations, affording cis-1,4/3,4 regulated 1,3-diene polymers. The polymerization of butadiene, interestingly, gives predominant cis-1,4 selectivity (>99.2%) with moderate activity. The substituent at ortho-position of arylimine plays a minor role in controlling activity and selectivity as well as the molecular weight of the resultant polymers. The properties of resultant poly(1,3-diene)s are stable even in a wide range of operational conditions, such as [Al]/[Co] varied from 20 to 600, temperature spanning from 0°C to 60°C, and monomer–catalyst ratio from 1000 to 4000. These additional benefits of minimum fluctuation in catalytic performances may be suitable for industrial polymerization process.

Copper Nitrate‐Mediated Selective Bond Cleavage of Alkynes: Diverse Synthesis of Isoxazoles

Posted on 8 September 2023 by nJianan Liu, nKaijing Zhou, nShaobo Sun, nMingchun Gao, nBin Xun

An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively.

Comprehensive Summary

An unprecedented copper nitrate-mediated bond cleavage of alkynes was developed for the modular synthesis of isoxazoles, where either C—S bond or C≡C triple bond was cleaved selectively. Substituents attached to the C≡C triple bonds could differentiate the chemical bonds cleavage and reaction pathways disparately. Various transformations of products illustrate promising applications of the given protocols.

The effect of structural variations of heteroleptic Cu(II) complexes of tri‐dentate unsymmetrical Schiff‐base main ligands with pyridine or bithiazole co‐ligands on molecular docking against SARS‐CoV‐2 and its Omicron variant main proteases

Posted on 8 September 2023 by nLiana Ghasemi, nMahdi Behzad, nAnita Abedi, nAli Khaleghiann

Meso-1,2-diphenyl-1,2-ethylenediamine was reacted with salicylaldehyde derivatives, copper(II) perchlorate, and pyridine to produce various four-coordinated heteroleptic [Cu (SBⁿ)(py)]ClO₄ (n = 1–4) complexes. Ligand exchange of the monodentate pyridine with bidentate 2,2′-dimethyl-4,4′-bithiazole (BTZ) produced other new series of five-coordinated [Cu (SB^na)(BTZ)]ClO₄ complexes. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet–visible (UV–Vis) spectroscopy were used to identify the complexes. The crystal structures of 1a and 2a were also determined by single-crystal X-ray crystallography (SCXRC). The inhibitory potential of these complexes against SARS-CoV-2 and its omicron variant main proteases (PDB IDs: 6LU7 and 7TLL, respectively) was investigated by means of molecular-docking modeling. According to the estimated free binding energy (EFBE), the order of binding energies were (3) > (3a) > (1a) > (1) > (2a) > (4a) > (4) > (2) for 6LU7 and (1a) > (3) > (1) > (4) > (2) > (4a) > (2a) > (3a) for 7TLL. The complexes (1a) for 6LU7 and (3) for 7TLL with electronegative Br substituents were at the top of the series and had the most negative ΔG_binding. The EFBE of four conventional corona-virus medicines, that is, remdesivir, hydroxychloroquine, dexamethasone, and AstraZeneca were also obtained and compared with the synthesized complexes. The EFBE of the complexes were comparable to standard drugs.

Tailoring chemical absorption–precipitation to lower the regeneration energy of a CO2 capture solvent

Posted on 8 September 2023 by

Solvent-based CO2 capture consumes significant energy in solvent recovery. To improve energy efficiency, this study investigates CO2 fixation in a solid form through solvation followed by ionic self-assembly–aided precipitation without requiring high energy for solvent regeneration. Based on hypothesis that CO2−3 ions may bind with monovalent metal ions such as Na+, we introduce monovalent Na+ into an aqueous hexane-1,6-diamine solution where CO2 forms carbamate and bicarbonate. Then, Na+ in the solvent act as a seed for ionic self-assembly with diamine carbamate to form an intermediate ionic complex. The recurring chemical reactions lead to an ionic solid formation, which can be easily removed through sedimentation or centrifugation from the aqueous solvent and heated to release the captured CO2. Direct heating of the solids leads to separation of CO2 via decomposition of a solid CO2-diamine-Na molecular aggregate, requiring as low as ~3.4 GJ/t CO2, which is significantly lower than the state-of-the-art polyethyleneimine, CaCO3, and bis-iminoguanidines systems, which require 3.5−10.2 GJ/t CO2. Molecular dynamic simulations support our hypothesis with the use of Na+ to form relatively less stable, yet sufficiently solid, complexes for the least energy-intensive recovery of diamine solvents compared with bivalent carbonate–forming ions.

Molecular engineering of inorganic halide perovskites and HTMs for photovoltaic applications

Posted on 8 September 2023 by nFaezeh Pakravesh, nMohammad Izadyarn

Theoretical analysis of V-J behavior demonstrated that the highest V_OC and J_SC related to LiPbF₃ and KSnCl_3, respectively.

Abstract

A comprehensive study was performed for the design of ABX₃ perovskites, (A = Li, K, Na, B = Ge, Sn, Pb, X = F, Cl, Br, I) and organic hole transfer materials, HTMs (Fu-2a, Fu-2b, Fu-2c, and Dm-Q) for efficient perovskite solar cells (PSCs) through quantum chemistry calculations. Photovoltaic characteristics of the investigated perovskites are strongly affected by the halide anions. The results reveal that reducing the exciton binding energy of perovskites enhances the rate of the formation/dissociation of holes and electrons so F-based perovskites are superior from this viewpoint. Additionally, the electron and hole injection processes are more favorable in the case of the F-based perovskites in comparison with other studied perovskites. Moreover, spectroscopic properties of the perovskites demonstrate that KSnCl₃, NaSnCl₃, and F-based perovskites exhibit a greater ability of the light-harvesting and incident photon to current conversion efficiency. Ultimately, based on diverse analyses, F-based perovskites, KSnCl₃ and NaSnCl₃ are the preferred candidates to be applied in the PSCs due to an excellent incident photon to current conversion efficiency, light-harvesting efficiency, short circuit current, and solar cell final efficiency.

The performance of hybrid and F12∗$$ {}^{\ast } $$/F12c explicitly correlated coupled cluster methods for use in anharmonic vibrational frequency computations

Posted on 8 September 2023 by nAlexandria G. Watrous, nBrent R. Westbrook, nRyan C. Fortenberryn

$The performance of hybrid and F12∗$$ {}^{\ast } $$/F12c explicitly correlated coupled cluster methods for use in anharmonic vibrational frequency computations$

The three components of the Taylor series approximation are computed via the F12-TcCR+$$ + $$DZ approach with the harmonics from F12-TcCR while the cubic and quartic terms are computed with F12-DZ. This method produces accurate results with relatively low computational cost.

Abstract

A hybrid quartic force field approach produces the same accuracies as non-hybrid methods but for less than one quarter of the computational time. This method utilizes explicitly correlated coupled cluster theory at the singles and doubles level inclusive of perturbative triples (CCSD(T)-F12b) in conjunction with a triple-ζ$$ \zeta $$ basis set, core electron correlation, and scalar relativity for the harmonic terms and CCSD(T)-F12b with a valence double-ζ$$ \zeta $$ basis set for the cubic and quartic terms. There is no sacrifice in the prediction of fundamental anharmonic vibrational frequencies or vibrationally-averaged rotational constants as compared to experiment, but the time saved is notable. Other hybrid methods are examined involving different sizes of basis sets and composite terms included or excluded. Not one is more accurate; only one is faster. F12∗$$ {}^{\ast } $$ (also called F12c) is tested as well, but it has an increase in computational time for no increase in accuracy. As such, this work reports a hybrid and composite approach (F12-TcCR+DZ) in the computation of rovibrational spectral data which can be applied to the observation of novel molecules in the gas phase in the laboratory and potentially even in astrophysical environments.

Cooperative Sensitization Upconversion in Ytterbium(III)‐Based Eosin Lake Pigments

Posted on 8 September 2023 by

Reacting the eosin Y (EOS) dianion and ytterbium(III) in ethanol and under basic conditions afforded an EOS-Yb lake pigment able to transform low-energy photons, specifically near-infrared (NIR) photons, into higher energy photons. The process eventually lead to long-lived sensitized emission of the dye (microseconds) through cooperative sensitization (CS) upconversion.

Abstract

Materials based on organic chromophores and lanthanides able to transform low-energy photons, specifically near-infrared (NIR) photons, into higher energy photons to eventually lead to long-lived sensitized emission of the dye are highly desirable. Cooperative sensitization (CS) upconversion has only been accomplished for lanthanide-based clusters. We used here the eosin Y (EOS) dianion and Yb³⁺ (EOS-Yb), and demonstrate the efficient CS emission of the dye after NIR excitation. Remarkably, the EOS dianion emission exhibits a nearly linear dependence on the EOS-Yb concentration and a quadratic dependence on the laser power density. The emission is non-sensitive to oxygen and its lifetime lasts about 1.76 μs and 12 μs in DMSO and DMSO-d₆ , respectively. Moreover, the effect of temperature (293–363 K range) on the EOS-Yb ¹H NMR spectroscopic shifts demonstrates the reversible dynamic nature of the material.

Ligand‐Independent Activation of Aryl Hydrocarbon Receptor and Attenuation of Glutamine Levels by Natural Deep Eutectic Solvent

Posted on 8 September 2023 by

A natural deep eutectic solvent, CAGE, derived from choline and geranic acid, perturb the metabolome, proteome, and transcriptome of human cell line. Specifically, CAGE upregulated 4-hydroxyphenyllactic acid and indole-3-lactic acid to activate the aryl hydrocarbon receptor, leading to the expression of IL1A, IL1B, CYP1A1, CYP1B1, ALDH31, NQO1. CAGE also attenuate the intracellular levels of glutamine.

Abstract

Natural deep eutectic solvents (NADESs) are emerging sustainable alternatives to conventional organic solvents. Beyond their role as laboratory solvents, NADESs are increasingly explored in drug delivery and as therapeutics. Their increasing applications notwithstanding, our understanding of how they interact with biomolecules at multiple levels - metabolome, proteome, and transcriptome - within human cell remain poor. Here, we deploy integrated metabolomics, proteomics, and transcriptomics to probe how NADESs perturb the molecular landscape of human cells. In a human cell line model, we found that an archetypal NADES derived from choline and geranic acid (CAGE) significantly altered the metabolome, proteome, and transcriptome. CAGE upregulated indole-3-lactic acid and 4-hydroxyphenyllactic acid levels, resulting in ligand-independent activation of aryl hydrocarbon receptor to signal the transcription of genes with implications for inflammation, immunomodulation, cell development, and chemical detoxification. Further, treating the cell line with CAGE downregulated glutamine biosynthesis, a nutrient rapidly proliferating cancer cells require. CAGE's ability to attenuate glutamine levels is potentially relevant for cancer treatment. These findings suggest that NADESs, even when derived from natural components like choline, can indirectly modulate cell biology at multiple levels, expanding their applications beyond chemistry to biomedicine and biotechnology.

[4.3.1]Bicyclic FKBP Ligands Inhibit Legionella Pneumophila Infection by LpMip‐Dependent and LpMip‐Independent Mechanisms

Posted on 8 September 2023 by

In a screening of over 1000 FKBP-inhibitors [4.3.1]-bicyclic sulfonamides turned out to be the preferred binding scaffold for LpMip, a virulence factor of Legionella pneumophila. Although selected [4.3.1]-bicyclic sulfonamides showed anti-infective properties, LpMip was ruled out as sole target, with the results suggesting another FKBP is responsible for the observed effects.

Abstract

Legionella pneumophila is the causative agent of Legionnaires’ disease, a serious form of pneumonia. Its macrophage infectivity potentiator (Mip), a member of a highly conserved family of FK506-binding proteins (FKBPs), plays a major role in the proliferation of the gram-negative bacterium in host organisms. In this work, we test our library of >1000 FKBP-focused ligands for inhibition of LpMip. The [4.3.1]-bicyclic sulfonamide turned out as a highly preferred scaffold and provided the most potent LpMip inhibitors known so far. Selected compounds were non-toxic to human cells, displayed antibacterial activity and block bacterial proliferation in cellular infection-assays as well as infectivity in human lung tissue explants. The results confirm [4.3.1]-bicyclic sulfonamides as anti-legionellal agents, although their anti-infective properties cannot be explained by inhibition of LpMip alone.

Laser Interfaced Mass Spectrometry of the Sunscreen Molecule Octocrylene Demonstrates that Protonation Does Not Impact Photostability

Posted on 8 September 2023 by

Laser photodissociation spectroscopy has been used to characterize the extent to which protonation affects the ability of octocrylene to act as an effective UV sunscreen molecule. We find that protonation results in a significant red shift of the absorption profile compared to non-protonated octocrylene, but does not impact on the ultrafast excited state decay pathways.

Abstract

Octocrylene (OCR) is a widely used organic sunscreen molecules, and is a dominant component of many sunscreen formulations. Here, we perform the first measurements on the protonated form of OCR, i. e. [OCR+H]⁺, to probe whether protonation affects the molecule's photostability. The novel photochemical technique of UV laser-interfaced mass spectrometry is employed from 400–216 nm, revealing that the electronic absorption spectrum of OCR across the S₁ and S₂ states red shift by 40 nm upon protonation. Our measurements reveal that [OCR+H]⁺ predominantly undergoes photofragmentation into the m/z 250 and 232 ionic products, associated with loss of its bulky alkyl side chain, and subsequent loss of water, respectively. We compare the photochemical fragmentation results with higher-energy collisional dissociation results to investigate the nature of the photodynamics that occur following UV absorption. The excited state decay pathways over the S₁ and S₂ excited states of [OCR+H]⁺ are associated with statistical fragmentation in line with dominant ultrafast decay. This behaviour mirrors that of neutral OCR, demonstrating that protonation does not affect the ultrafast decay pathways of this sunscreen molecule. We discuss our results in the context of the known breakdown of OCR into benzophenone, identifying a potential photoactivated pathway to benzophenone formation in solution.