In the title compound, C25H23FN2O4S, the fused piperidine ring of the octa-hydro-indolizine ring system adopts a chair conformation and the five-membered ring has a twisted conformation on the N-C(spiro) bond. The mean planes of the benzo-thio-phene and indoline ring systems are inclined to the mean plane of the pyrrolidine ring by 83.1 (1) and 84.9 (1)°, respectively, and to each other by 29.37 (17)°. In the crystal, mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif. The dimers are linked via C-H⋯O hydrogen bonds, forming slabs lying parallel to (100). The packing between the slabs features a short [2.734 (2) Å] F⋯F contact.
Chitosan is a nontoxic biopolymer with many potential biomedical and material applications due to its biodegradability, biocompatibility, and antimicrobial properties. Here, fully atomistic molecular dynamics simulations and enhanced sampling methods have been used to study the adsorption mechanism of chitosan oligomers on a silica surface from an aqueous solution. The free energy of adsorption of chitosan on a silica surface was calculated to be 0.
Self-assembling cyclic peptide nanotubes are fascinating supramolecular systems with promising potential for various applications, such as drug delivery, transmembrane ionic channels, and artificial light-harvesting systems. In this study, we present novel pH-responsive nanotubes based on asymmetric cyclic peptide-polymer conjugates. The pH response is introduced by a tertiary amine-based polymer, poly(dimethylamino ethyl methacrylate) (pDMAEMA) or poly(diethylamino ethyl methacrylate) (pDEAEMA) which is protonated at low pH.
Herein, we present a strategy to access a novel class of pH-responsive, dual-state emissive (DSE), highly fluorescent pyrrole-based chromophores diformylation of dipyrroethenes (DPE) followed by condensation with various aniline derivatives. The DPE-based chromophores exhibit a large Stokes shift and maintain good fluorescence quantum yields. Remarkably, these chromophores demonstrate reversible colourimetric changes and a fluorometric 'on-off-on' switch in response to pH variations.
Binary ionic melts formed by a protic ionic liquid (PIL) 1,2,4-triazolium methanesulfonate ([TAZ][MS]) dissolved in methanesulfonic acid are studied as non-stoichiometric electrolytes. The composition-driven structure-property relationship of methanesulfonic acid is explored at varying molar fraction ratios from 0/100 to 10/90, 20/80, and 30/70 by the addition of 1,2,4-triazolium methanesulfonate [TAZ][MS] IL. To unveil molecular characteristics of these mixtures of [TAZ][MS] PIL and CHSOH, we performed classical molecular dynamics simulations at varying temperatures from 293 to 303, 363, and 423 K.
The modification of Pt surfaces with organic compounds like melamine enhances oxygen reduction reaction activity and catalyst durability. Through first-principles free energy calculations utilizing thermodynamic integration and finite-temperature molecular dynamics, enhanced by machine learning force fields for efficient sampling of nanosecond-scale interfacial water fluctuations and incorporating corrections to accurately reproduce first-principles free energies, we demonstrate that melamine destabilizes OH adsorbates, facilitating their removal and enhancing catalytic activity. Unlike alloys, where OH destabilization is driven by changes in electronic structure and surface strain, melamine disrupts hydrogen bonding between OH and interfacial water.
