Vazquezlindegaard4028

By employing the Bethe-Salpeter formalism coupled with a nonequilibrium embedding scheme, we demonstrate that the paradigmatic case of S1 band separation between cis and trans in azobenzene derivatives can be computed with excellent accuracy compared to experimental optical spectra. PQR309 manufacturer Besides embedding, we show that the choice of the Kohn-Sham exchange correlation functional for DFT is critical, despite the iterative convergence of GW quasiparticle energies. We address this by adopting an orbital-tuning approach via the global hybrid functional, PBEh, yielding an environment-consistent ionization potential. The vertical excitation energy of 20 azo molecules is predicted with a mean absolute error as low as 0.06 eV, up to three times smaller compared to standard functionals such as M06-2X and PBE0, and five times smaller compared to recent TDDFT results.Binding-induced mechanical stabilization plays key roles in proteins involved in muscle contraction, cellular mechanotransduction, or bacterial adhesion. Because of the vector nature of force, single-molecule force spectroscopy techniques are ideal for measuring the mechanical unfolding of proteins. However, current approaches are still prone to calibration errors between experiments and geometrical variations between individual tethers. Here, we introduce a single-molecule assay based on magnetic tweezers and heterocovalent attachment, which can measure the binding of the substrate-ligand using the same protein molecule. We demonstrate this approach with protein L, a model bacterial protein which has two binding interfaces for the same region of kappa-light chain antibody ligands. Engineered molecules with eight identical domains of protein L between a HaloTag and a SpyTag were exposed to repeated unfolding-refolding cycles at forces up to 100 pN for several hours at a time. The unfolding behavior of the same protein was measured in solution buffers with different concentrations of antibody ligands. With increasing antibody concentration, an increasing number of protein L domains became more stable, indicative of ligand binding and mechanical reinforcement. Interestingly, the dissociation constant of the mechanically reinforced states coincides with that measured for the low-avidity binding interface of protein L, suggesting a physiological role for the second binding interface. The molecular approach presented here opens the road to a new type of binding experiments, where the same molecule can be exposed to different solvents or ligands.Phosphorescence of organic molecules has drawn extensive attention due to its potential applications in energy and life science. However, typically intersystem crossing (ISC) in organic molecules is slow due to the small spin-orbit couplings (SOC) and large energy gaps (ΔES-T) between different multiplicities. Molecular aggregation offers a practical strategy to manipulate phosphorescent characteristics. In this work, the impact of aggregation on the luminescence properties of π-conjugated benzophenone luminophore 1-dibenzo[b,d]thiophen-2-yl(phenyl)methanone (BDBT) are investigated theoretically using density functional theory (DFT) and time-dependent DFT. Molecular aggregation results in substantial energy splitting and variation of SOC, eventually changing the ISC rate. This is known as the "aggregation-induced intersystem crossing" (AI-ISC) mechanism. Different types of electron donating and withdrawing functional groups are further introduced into BDBT molecular system to tailor the phosphorescent efficiency. We find that functional groups can influence the SOC and energy gaps and further manipulate the phosphorescence efficiency. Molecular systems with donating functional groups have faster ISC rates, and dimers exhibit the best electronic luminescence due to the relatively large SOC and small ΔES-T. The AI-ISC mechanism accompanied by group functionalization provides a practical platform for phosphorescence enhancement.Increased usage of daptomycin to treat infections caused by Gram-positive bacterial pathogens has resulted in emergence of resistant mutants. In a search for more effective daptomycin analogues through medicinal chemistry studies, we found that methylation at the nonproteinogenic amino acid kynurenine in daptomycin could result in significant enhancement of antibacterial activity. Termed "kynomycin," this new antibiotic exhibits higher antibacterial activity than daptomycin and is able to eradicate methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) strains, including daptomycin-resistant strains. The improved antimicrobial activity of kynomycin was demonstrated in in vitro time-killing assay, in vivo wax worm model, and different mouse infection models. The increased antibacterial activity, improved pharmacokinetics, and lower cytotoxicity of kynomycin, compared to daptomycin, showed the promise of the future design and development of next-generation daptomycin-based antibiotics.The protonation sites of aniline molecule play important roles in its chemical reactions, but the preferred protonation site of gaseous aniline has yet to be determined. In this work, we recorded infrared (IR) absorption spectra of three isomers of protonated aniline, H+C6H5NH2, produced on electron bombardment during matrix deposition at 3.2 K of a mixture of aniline and para-H2. The intensities of IR lines of H+C6H5NH2 decreased during maintenance of the electron-bombarded matrix in darkness because of neutralization with electrons that were slowly released from their trapping sites. The observed lines were classified into three groups according to their behavior upon secondary photolysis with light at 375 and 254 nm and assigned to para-, amino-, and ortho-H+C6H5NH2, the three most stable isomers of protonated aniline, according to comparison of experimental spectra with quantum-chemically predicted spectra of five possible isomers of H+C6H5NH2. The spectra of para- and ortho-H+C6H5NH2 are newly distinguished. The approximate relative abundance of these isomers in solid p-H2 was paraaminoortho ≈ (1.0 ± 0.1)(1.0 ± 0.6)(0.6 ± 0.1). The possible mechanisms of formation are discussed.