Search results for " Computational Chemistry"
showing 10 items of 28 documents
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.
Structure-property relationships in aromatic thioethers featuring aggregation-induced emission : Solid-state structures and theoretical analysis
2019
We describe in this paper a structure–property relationship study of aromatic thioethers with aggregation-induced emission (AIE) properties. We combine a structural analysis based on geometrical consideration with an in-depth analysis of the crystalline packing supported by quantum mechanical calculations. Our results allow us to correlate the enhanced fluorescence quantum yields with the significant increase of C–H⋯π and the decrease of π⋯π interactions in the solid state – a result which supports the well-accepted AIE mechanism quantitatively.
Structural and Kinetic DFT Characterization of Materials to Rationalize Catalytic Performance
2009
This review shortly discusses recent results obtained by the application of density functional theory for the calculations of the adsorption and diffusion properties of small molecules and their reactivity on heterogenous catalytic systems, in the ambit of the Nanocat project. Particular focus has been devoted to palladium catalysts, either in atomic or small cluster form. Some protocols have been tested to obtain efficient ways able to treat the electronic and geometric influence of supports like zeolites and carbon nanotubes on the catalytic properties of palladium. The hydroisomerization of cis-but-2-ene is discussed as model reaction on supported and unsupported Pd clusters. Some prelim…
Modelling Photoionisation in Isocytosine: Potential Formation of Longer‐Lived Excited State Cations in its Keto Form
2021
Abstract Studying the effects of UV and VUV radiation on non‐canonical DNA/RNA nucleobases allows us to compare how they release excess energy following absorption with respect to their canonical counterparts. This has attracted much research attention in recent years because of its likely influence on the origin of our genetic lexicon in prebiotic times. Here we present a CASSCF and XMS‐CASPT2 theoretical study of the photoionisation of non‐canonical pyrimidine nucleobase isocytosine in both its keto and enol tautomeric forms. We analyse their lowest energy cationic excited states including 2π+ , 2nO+ and 2nN+ and compare these to the corresponding electronic states in cytosine. Investigat…
Water-Dependent Blending of Pectin Films: The Mechanics of Conjoined Biopolymers
2020
Biodegradable pectin polymers have been recommended for a variety of biomedical applications, ranging from the delivery of oral drugs to the repair of injured visceral organs. A promising approach to regulate pectin biostability is the blending of pectin films. To investigate the development of conjoined films, we examined the physical properties of high-methoxyl pectin polymer-polymer (homopolymer) interactions at the adhesive interface. Pectin polymers were tested in glass phase (10&ndash
A DFT study of IRMOF-3 catalysed Knoevenagel condensation
2011
It has been recently reported that IRMOF-3 [Gascon et al., J. Catal, 2009, 261, 75] may behave as a basic catalyst, active in the Knoevenagel condensation. In particular, it has been shown that the basicity of aniline-like amino moieties is enhanced, along with the catalytic activity, when incorporated into MOF structures. The computational study here was aimed at finding possible atomistic explanations of the increased basicity and catalytic activity of the IRMOF-3 embedded aniline groups, experimentally claimed. It was, moreover, aimed at guessing a reaction mechanism for the IRMOF-3 catalysed Knoevenagel condensation of benzaldehyde and ethyl-cyanoacetate. Within the DFT framework we hav…
Selective G-quadruplex stabilizers: Schiff-base metal complexes with anticancer activity
2014
The affinity of three square-planar nickel(II) (1), copper(II) (2) and zinc(II) (3) Schiff-base complexes for wild-type human telomeric (h-Telo) and protooncogene c-myc G-quadruplex (G4) DNA was investigated by UV-visible absorption spectroscopy and circular dichroism. DNA-binding constants (Kb) were determined by spectrophotometric titrations for both G4-DNA and B-DNA. The results obtained point out that the three metal complexes selectively bind G4-DNA with higher affinity, up to two orders of magnitude, with respect to B-DNA. The nickel(II) complex 1 was found to be the most effective G4-DNA stabilizer and the Kb values decrease in the order 1 > 2 ≈ 3. Innovative computational investigat…
G4-DNA vs. B-DNA binding of Schiff base transition metal complexes
2014
The competitive binding of nickel(II), copper(II) and zinc(II) complexes toward B- and G4-DNA was addressed through spectroscopic titrations and rationalized by computational investigations, consisting of molecular dynamics simulations followed by density functional theory/molecular mechanics (DFT/MM) calculations [1]. The experimental DNA binding studies clearly highlight the selectivity of the compounds, in particular the nickel(II) complex, toward G4-DNA from both h-Telo and c-myc. Moreover, the compounds show biological activity against HeLa and MCF-7 cancer cell lines. Remarkably, the experimental DNA-binding affinity trend of the three metal complexes, obtained from the DNA-binding co…
DNA-Binding of NiII, CuII and ZnII Complexes of Salen Derivatives
2014
Nickel(II), copper(II) and zinc(II) complexes of N2O2 tetradentate Schiff base ligands strongly interact with B-DNA, usually by groove-binding and/or by intercalation [1]. It has been also shown that the presence of aromatic substituents on the N,N’ bridge make them suitable G-quadruplex binders [2]. In this context, we have recently investigated the binding toward duplex and G-quadruplex DNA of nickel(II), copper(II) and zinc(II) complexes of N,N’-bis-5-(triethyl ammonium methyl)-salicylidene-2,3-naphthalendiiminato) (see Figure), by spectroscopic and computational methods [3,4]. The compounds show also biological activity against human cancer cell lines. Different substituents are present…
Computational Studies of Materials for Energy Technology: CO2 Methanation, and Halloysite Carbon-Coating
2022
The models and theories of quantum chemistry are applied in order to study two kinds of materials of interest in the field of energy technology, to understand their behavior and to verify their suitability for possible application. In particular, the effect of single Ru/Fe atom deposition on the CO2 methanation reaction occurring on the Ni(111) surface, and the effect on the band gap produced by carbon atom deposition and carbon cluster accretion on the silicic surface of halloysite, have been investigated by means of the periodic and molecular flavours of density functional theory. In order to accomplish the investigations above two entirely new computer codes were written and are actually…