Search results for "Non-covalent interactions"
showing 10 items of 73 documents
Towards Atomically Precise Supported Catalysts from Monolayer‐Protected Clusters: The Critical Role of the Support
2020
Abstract Controlling the size and uniformity of metal clusters with atomic precision is essential for fine‐tuning their catalytic properties, however for clusters deposited on supports, such control is challenging. Here, by combining X‐ray absorption spectroscopy and density functional theory calculations, it is shown that supports play a crucial role in the evolution of monolayer‐protected clusters into catalysts. Based on the acidic nature of the support, cluster‐support interactions lead either to fragmentation of the cluster into isolated Au–ligand species or ligand‐free metallic Au0 clusters. On Lewis acidic supports that bind metals strongly, the latter transformation occurs while pre…
Experimental investigation of anion-π interactions : Applications and biochemical relevance
2015
Chemical communications 52(9), 1778 - 1795(2016). doi:10.1039/C5CC09072E
Hierarchical Self-Organization of Perylene Bisimide–Melamine Assemblies to Fluorescent Mesoscopic Superstructures
2000
A series of three perylene tetracarboxylic acid bisimide dyes 3a-c bearing phenoxy substituents at the four bay positions of the perylene core were synthesized and their complexation behavior to complementary ditopic dialkyl melamines 8a-c was investigated. Binding constants and Gibbs binding energies for the hydrogen bonds between the imide and the complementary melamine moiety have been determined in several solvents by NMR and UV/Vis titration experiments with monotopic model compounds 5 and 9. The effects of the solvent polarity and specific solvent-solute interactions on the degree of polymerization of (3 x 8)n are discussed, and a general formula to estimate the chain length of [AA-BB…
Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry
2016
A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through a rigorous quantum chemical analysis of the changes of the electron density as well as the energies associated with these changes along the reaction path in order to understand experimental outcomes. St…
Tellurium( II ) Dialkanethiolates: n p (S)‐σ*(Te−S′) Orbital Interactions Determine the 125 Te NMR Chemical Shift, and the Molecular and Crystal Stru…
2003
Tellurium(II) dimethanethiolate, Te(SMe)(2), and tellurium(II) diethanethiolate, Te(SEt)(2), were synthesized by reaction of TeO2 and Te(OiPr)(4) with HSMe and HSEt, respectively. In the solid state, Te(SMe)(2) exhibits a cis-conformation of the methyl groups with respect to the TeS2 plane - an unprecedented situation for nonfunctionalized organotrichalcogenides - whereas Te(SEt)(2) shows a trans-conformation. Ab initio calculations performed for Te(SMe)(2) and Te(SEt)(2) show that the cis- and trans-conformers represent minima on the potential energy surface and are stabilized by intramolecular pi-type n(S)-sigma* (Te-S') orbital interactions. In the solid state, the molecules of each comp…
Synthesis and Characterizations of Novel Isatin-s-Triazine Hydrazone Derivatives : X-ray Structure, Hirshfeld Analysis and DFT Calculations
2023
A novel series of isatin-s-triazine hydrazone derivatives has been synthesized and reported herein. The synthetic methodology involved the reaction of s-triazine hydrazine precursors with isatin derivatives in the presence of CH3COOH as a catalyst and EtOH as solvent to afford the corresponding target products 6a-e in high yields and purities. The characterization data obtained from elemental analysis, FT-IR, NMR (1H- and 13C-) were in full agreement with the expected structures. Furthermore, an X-ray single crystal diffraction study of one of the target s-triazine hydrazone derivatives, 6c confirmed the structure of the desired compounds. It crystallized in the triclinic crystal system and…
Mass Spectrometric Investigation of Noncovalent Complexation between a Tetratosylated Resorcarene and Alkyl Ammonium Ions
2004
Noncovalent complexation between tetratosylated tetraethyl resorcarene (1) and primary, secondary, and tertiary alkyl ammonium ions (mMe, dMe, tMe, mEt, dEt, tEt, dBu, and dHex) was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Interactions of the noncovalent complexes were investigated by means of competition experiments, collision-induced dissociation (CID) experiments, ion-molecule reactions with tripropylamine and gas phase H/D-exchange reactions with deuteroammonia. Gas phase ion-molecule reactions gave especially valuable information about the structure and properties of the complexes. Resorcarene 1 formed relatively stable…
Bridging rigidity and flexibility : modulation of supramolecular hydrogels by metal complexation
2021
The combination of complementary, noncovalent interactions is a key principle for the design of multistimuli responsive hydrogels. In this work, an amphiphilic peptide, supramacromolecular hydrogelator which combines metal-ligand coordination induced gelation and thermoresponsive toughening is reported. Following a modular approach, the incorporation of the triphenylalanine sequence FFF into a structural (C3EG ) and a terpyridine-functionalized (C3Tpy ) C3 -symmetric monomer enables their statistical copolymerization into self-assembled, 1D nanorods in water, as investigated by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the presence of a terpyridine …
Hierarchical Self-Assembly of Halogen-Bonded Block Copolymer Complexes into Upright Cylindrical Domains
2017
Summary Self-assembly of block copolymers into well-defined, ordered arrangements of chemically distinct domains is a reliable strategy for preparing tailored nanostructures. Microphase separation results from the system, minimizing repulsive interactions between dissimilar blocks and maximizing attractive interactions between similar blocks. Supramolecular methods have also achieved this separation by introducing small-molecule additives binding specifically to one block by noncovalent interactions. Here, we use halogen bonding as a supramolecular tool that directs the hierarchical self-assembly of low-molecular-weight perfluorinated molecules and diblock copolymers. Microphase separation …
Quantum-Chemical Insights into the Self-Assembly of Carbon-Based Supramolecular Complexes
2018
Understanding how molecular systems self-assemble to form well-organized superstructures governed by noncovalent interactions is essential in the field of supramolecular chemistry. In the nanoscience context, the self-assembly of different carbon-based nanoforms (fullerenes, carbon nanotubes and graphene) with, in general, electron-donor molecular systems, has received increasing attention as a means of generating potential candidates for technological applications. In these carbon-based systems, a deep characterization of the supramolecular organization is crucial to establish an intimate relation between supramolecular structure and functionality. Detailed structural information on the se…