Accounting for van der Waals interactions between adsorbates and surfaces in density functional theory based calculations: selected examples

This article reviews the different density functional theory (DFT) methods available in the literature for dealing with dispersion interactions and recent applications of DFT approaches including van der Waals corrections in the study of the interaction of atoms and molecules with several different surfaces. Focus is given to the interaction of atoms and molecules with metal, metal oxide and graphite surfaces or more complex systems. It will be shown that DFT approaches including van der Waals corrections present significant advances over standard exchange-correlation functionals for treating systems dominated by weak interactions

A simple method for labelling and detection of proteinaceous binders in art using fluorescent coumarin derivatives

The identification of protein binders used in easel paintings is an important information to understand an artist’s technique and for making informed conservation and restoration decisions. The present work presents a novel fluorescent labelling methodology, using a coumarin derivative chromophore, C392STP (sodium (E/Z)-4-(4-(2-(6,7-dimethoxy-coumarin-3-yl) vinyl) benzoyl)-2,3,5,6- tetrafluorobenzenesulfonate), as a fluorophore probe to bond proteinaceous binders used in paintings, followed by separation and identification with protein patterns, by electrophoretic processes. Additionally, theoretical quantum chemical calculations based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) have been performed in a coumarin derivative, which mimics the coumarin bound to the proteins. The optimized methodology was tested on proteinaceous binder extracted from paint model micro-samples. The results evidence the applicability of this methodology as an effective and useful analytical tool for the identification of protein binders obtained from easel paintings

A chiral electrochemical system based on l-cysteine modified gold nanoparticles for propranolol enantiodiscrimination: Electroanalysis and computational modelling

Enantioselective electrochemical sensors seem to hold the promise for a fast and easy alternative for the chiral probing of bioactive molecules. However, the underlying mechanism responsible for the chiral recognition is rarely known, and suitable investigational tools are dearly missed. Therefore, as a proof-ofconcept, our study is focused on investigating the interaction mechanism of the enantiomers of a chiral drug molecule, namely propranolol (PRNL) with the surface of bare and L-cysteine (L-Cys) modified gold nanoparticles employing various electrochemical techniques (differential pulse voltammetry and electrochemical impedance spectroscopy) and computational modeling (molecular dynamics simulations). If the strong surface adsorption of PRNL antipodes on bare gold nanoparticles may not be exploited for enantioselective recognition, upon the functionalization of the nanostructures with L-Cys, the almost two fold increase in the oxidation current is also accompanied by a cathodic shift (~40 mV) of the peak potential for the S( )-enantiomer. This peak potential shift seems to be the consequence of a favored orientation of the surface adsorbed S( )-enantiomer towards electron transfer and/or a weaker interaction with the chiral selector and thus a higher free energy of the transient diastereoisomeric complex, in comparison with its R(þ)-antipode. Computational modeling highlighted the H-bond donor and acceptor atoms of both the chiral selector (L-Cys) and adsorbates (PRNL enantiomers) responsible for the recorded enantioselective electrochemical signal. Correlations between the observed electrochemical signal and enantioselective molecular interactions occurring at the surface of the electrode may lead the way towards a more rational design of future chiral electrochemical sensing platforms