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Filtenborg Schack posted an update 5 months, 4 weeks ago
An efficient basis representation of time-dependent wavefunctions is essential for theoretical studies of high-dimensional molecular systems exhibiting large-amplitude motion. For fully coupled anharmonic systems, the complexity of a general wavefunction scales exponentially with the system size; therefore, for practical reasons, it is desirable to adapt the basis to the time-dependent wavefunction at hand. Often times on this quest for a minimal basis representation, time-dependent Gaussians are employed, in part because of their localization in both configuration and momentum spaces and also because of their direct connection to classical and semiclassical dynamics, guiding the evolution of the basis function parameters. In this work, the quantum-trajectory guided adaptable Gaussian (QTAG) bases method is generalized to include correlated, i.e., non-factorizable, basis functions, and the performance of the QTAG dynamics is assessed on benchmark system/bath tunneling models of up to 20 dimensions. For the popular choice of initial conditions describing tunneling between the reactant/product wells, the minimal “semiclassical” description of the bath modes using essentially a single multidimensional basis function combined with the multi-Gaussian representation of the tunneling mode is shown to capture the dominant features of dynamics in a highly efficient manner.Nanoscale imine-linked covalent organic frameworks (nCOFs) were first loaded with the anticancer drug Doxorubicin (Dox), coated with magnetic iron oxide nanoparticles (γ-Fe2O3 NPs), and stabilized with a shell of poly(l-lysine) cationic polymer (PLL) for simultaneous synergistic thermo-chemotherapy treatment and MRI imaging. The pH responsivity of the resulting nanoagents (γ-SD/PLL) allowed the release of the drug selectively within the acidic microenvironment of late endosomes and lysosomes of cancer cells (pH 5.4) and not in physiological conditions (pH 7.4). γ-SD/PLL could efficiently generate high heat (48 °C) upon exposure to an alternating magnetic field due to the nCOF porous structure that facilitates the heat conduction, making γ-SD/PLL excellent heat mediators in an aqueous solution. The drug-loaded magnetic nCOF composites were cytotoxic due to the synergistic toxicity of Dox and the effects of hyperthermia in vitro on glioblastoma U251-MG cells and in vivo on zebrafish embryos, but they were not significantly toxic to noncancerous cells (HEK293). To the best of our knowledge, this is the first report of multimodal MRI probe and chemo-thermotherapeutic magnetic nCOF composites.Using both multi-informative molecular network and score-based approaches as prioritization strategies, the Northeastern Atlantic marine terebellid Eupolymnia nebulosa was selected for in-depth chemical investigation. A family of 16 new metabolites named nebulosins was isolated and structurally characterized from extensive analyses of HRMS/MS and NMR spectroscopic data. Nebulosins feature an unprecedented highly substituted thiolane ring leading to up to four contiguous chiral centers. The relative configurations were assigned through a combination of NOESY analysis, spin-spin coupling constant analysis, and NMR chemical shifts measurements, while the absolute configurations were determined by comparison between experimental and theoretical ECD spectra. This family of natural product exhibits promising antioxidant activities in both ORAC and ROS assays.Fluorescent molecules, fluorophores or dyes, play essential roles in bioimaging. Effective bioimaging requires fluorophores with diverse colors and high quantum yields for better resolution. An essential computational component to design novel dye molecules is an accurate model that predicts the electronic properties of molecules. PBIT Histone Demethylase inhibitor Here, we present statistical machines that predict the excitation energies and associated oscillator strengths of a given molecule using the random forest algorithm. The excitation energies and oscillator strengths of a molecule are closely related to the emission spectrum and the quantum yields of fluorophores, respectively. In this study, we identified specific molecular substructures that induce high oscillator strengths of molecules. The results of our study are expected to serve as new design principles for designing novel fluorophores.The controlled generation of hydrogen sulfide (H2S) under biologically relevant conditions is of paramount importance due to therapeutic interests. Via exploring the reactivity of a structurally characterized phenolate-bridged dinuclear zinc(II)-aqua complex LZnII(OH2)2(ClO4)2 (1a) as a hydrolase model, we illustrate in this report that complex 1a readily hydrolyses CS2 in the presence of Et3N to afford H2S. In contrast, penta-coordinated sites in dinuclear (LZnII)2(μ-X)(ClO4) complexes (7, X = OAc; 8, X = dimethylpyrazolyl) do not mediate CS2 hydrolysis in the presence of externally added water and Et3N presumably due to the unavailability of a coordination site for water at the centers. Moreover, -OH sites present in the isolated tetranuclear zinc(II) complex (LZnII)2(μ-OH)2(ClO4)2 (4) react with CS2, thereby suggesting that the -OH site serves as the active nucleophile. Furthermore, mass spectrometric analyses on the reaction mixture consisting of 1a/Et3N and CS2 suggest the involvement of zinc(II)-thiocarbonate (3a) and COS species, thereby providing mechanistic insights into CS2 hydrolysis mediated by the dinuclear hydrolase model complex 1a.A practical two-step synthesis of N,N’-disubstituted cyanamides consists in the low-temperature metalation of N-substituted 5H-tetrazoles that undergo spontaneous cycloreversion at 0 °C releasing dinitrogen, and forming N-metalated cyanamides that can be reacted in situ with a variety of electrophiles. Remarkably, the N-substituted Li and K cyanamides are air stable white solids at room temperature. Addition of lithium organometallics to the N,N’-disubstituted cyanamides provides a new method for accessing N,N’-disubstituted amidines.Mucin glycoproteins are the matrix-forming key components of mucus, the innate protective barrier protecting us from pathogenic attack. However, this barrier is constantly challenged by mucin-degrading enzymes, which tend to target anionic glycan chains such as sulfate groups and sialic acid residues. Here, we demonstrate that the efficiency of both unspecific and specific binding of small molecules to mucins is reduced when sulfate groups are enzymatically removed from mucins; this is unexpected because neither of the specific mucin-binding partners tested here targets these sulfate motifs on the mucin glycoprotein. Based on simulation results obtained from a numerical model of the mucin macromolecule, we propose that anionic motifs along the mucin chain establish intramolecular repulsion forces which maintain an elongated mucin conformation. In the absence of these repulsive forces, the mucin seems to adopt a more compacted structure, in which the accessibility of several binding sites is restricted. Our results contribute to a better understanding on how different glycans contribute to the broad spectrum of functions mucin glycoproteins have.
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