Search results for " hydrogen bonding"
showing 10 items of 27 documents
Crystal structure of bis(cyclohexylammonium) diphenyldioxalatostannate(IV)
2015
In the title salt, (CyNH3)2[Sn(Ph2)(C2O4)2] (Cy is cyclohexyl and Ph is phenyl), the SnPh2 moiety is chelated by two oxalate anions, leading to a cis arrangement within the distorted octahedral coordination sphere of the SnIV atom.
Solubility and solvation features of native cyclodextrins in 1-ethyl-3-methylimidazolium acetate
2022
The comprehension of the mechanism entailing efficient solvation of cyclodextrins (CD) by green solvents is of great relevance to boost environmentally sustainable usages of smart supramolecular systems. Here, 1-ethyl-3- methylimidazolium acetate, an ecofriendly ionic liquid (IL), is considered as an excellent solvent for native CDs. This IL efficiently dissolves up to 40 wt.% β- and γ-CD already at ambient temperature and X-ray scattering indicates that CDs do not tend to detrimental flocculation under these drastic concentration conditions. Simu- lation techniques reveal the intimate mechanism of CD solvation by the ionic species: while the strong hydrogen bonding acceptor acetate anion i…
Crystal structure and Hirshfeld surface analysis of (E)-3-(benzylideneamino)-5-phenylthiazolidin-2-iminium bromide
2020
The central thiazolidine ring of the title salt, C16H16N3S+center dot Br-, adopts an envelope conformation, with the C atom bearing the phenyl ring as the flap atom. In the crystal, the cations and anions are linked by N-H center dot center dot center dot Br hydrogen bonds, forming chains parallel to the b-axis direction. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H center dot center dot center dot H (46.4%), C center dot center dot center dot H/H center dot center dot center dot C (18.6%) and H center dot center dot center dot Br/Br center dot center dot center dot H (17.5%) interactions.
Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)- Dodecyl (2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium Bromide (DMEB)
2014
(1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) aggregates dispersed in carbon tetrachloride have been investigated by Fourier transform infrared (FT-IR), vibrational circular dichroism (VCD) and 1H nuclear magnetic resonance (NMR) spectroscopy at various surfactant concentration and water-to-surfactant molar ratio. Experimental data indicate that, even at the lowest investigated concentration and in absence of added water, DMEBmolecules associate in supramolecular assemblies. At higherDMEBconcentration the aggregates can confine watermolecules,making it plausible to think thatDMEB form reverse micelles and that watermolecules are quite uniformly distributed…
Structure of anisole derivatives by total neutron and X-ray scattering: Evidences of weak C–H⋯O and C–H⋯π interactions in the liquid state
2020
Abstract High resolution, total neutron and X-ray scattering data have been used in synergy with Molecular Dynamics simulations to access atomistic scale insight into the structure of anisole and 2,3,5-trimethylanisole, two aromatic compounds bearing an electron-donating methoxy group. A detailed description is provided for the main interactions occurring in these systems, including π-π stacking and weak hydrogen bonding correlations: C H⋯O and C H⋯π. The existence of preferential orientations of the first shell coordinating molecules and the specific nature of the interactions involving the π cloud and the polar methoxy group have been reported and discussed.
Liquid Structure Scenario of the Archetypal Supramolecular Deep Eutectic Solvent: Heptakis(2,6-di-O-methyl)-β-cyclodextrin/levulinic Acid
2023
The concept of supramolecular solvents has been recently introduced, and the extended liquid-state window accessible for mixtures of functionalized cyclodextrins (CDs) with hydrogen bond (HB) donor species, e.g., levulinic acid, led to the debut of supramolecular deep eutectic solvents (SUPRA-DES). These solvents retain CD’s inclusion ability and complement it with enhanced solvation effectiveness due to an extended HB network. However, so far, these promising features were not rationalized in terms of a microscopic description, thus hindering a more complete capitalization. This is the first joint experimental and computational study on the archetypal SUPRA-DES: heptakis- (2,6-di-O-methyl)…
Mesogens with Aggregation-Induced Emission Formed by Hydrogen Bonding
2019
In this contribution, we report a supramolecular approach toward mesogens showing aggregation-induced emission (AIE). AIE-active aromatic thioethers, acting as hydrogen-bond donors, were combined with alkoxystilbazoles as hydrogen-bond acceptors. Upon self-assembly, hydrogen-bonded complexes with monotropic liquid crystalline behavior were obtained. In addition, it was found that the introduction of a chiral citronellyl side chain leads to drastic bathochromic shift of the emission, which was not observed for linear alkyl chains. The mesomorphic behavior, as well as the photophysical properties as a solid and in the mesophase of the liquid crystalline assemblies, were studied in detail.
Hydrogen-bonded liquid crystals with broad-range blue phases
2019
We report a modular supramolecular approach for the investigation of chirality induction in hydrogen-bonded liquid crystals. An exceptionally broad blue phase with a temperature range of 25 °C was found, which enabled its structural investigation by solid state 19F-NMR studies and allowed us to report order parameters of the blue phase I for the first time.
From self-inclusion and host-guest complexes to channel structures
2012
Various supramolecular interactions are applied as driving forces in self-assembly and molecular recognition processes. Single crystal X-ray diffraction method is especially important for solid-state studies of non-covalent interactions as it reveals their influence on the molecular and supramolecular structures. This paper discusses structures of two completely different types of compounds in which a variety of intermolecular interactions are involved. It will be shown that strong and weak intermolecular hydrogen bonds in N-alkylammonium resorcinarene salts, depending on the type of anion, inclusion of resorcinarene upper rim pendant group or solvent molecules into the cavity, strongly aff…
Hydrogen bond-stabilised N-alkylammonium resorcinarene halide cavitands
2010
A family of hydrogen bond-stabilised N-alkylammonium resorcinarene chloride and bromide cavitands were synthesised and characterised with 1H NMR and ESI mass spectrometry. The seven compounds exhibit interestingly either self-inclusion or guest complexation in the solid state evidenced by single crystal X-ray diffraction. The four dimers show self-inclusion of the upper rim propyl chains and consist of two hydrogen-bonded resorcinarene tetracations and six halide anions, while the remaining two halide anions are located in between the dimers linking them via hydrogen bonding. Small solvent molecules such as dichloromethane, methanol, n-butanol or chloroform are complexed into the resorcinar…