Latest Publications

DOI: 10.1021/acs.jpcc.9b06805

The Journal of Physical Chemistry C 2019

We present a theoretical investigation of the reactivity of both a pristine CeO2 surface and a small Ag cluster adsorbed on a CeO2 surface towards H2, using a periodic spin-polarized hybrid density functional theory approach. The dissociation of H2 and subsequent formation of H2O have been considered in order to highlight the role of the metal structure and its underlying metal oxide support as a potential candidate as a catalyst to the above-mentioned reactions. Structural, energetic, electronic and vibrational properties of all species involved in the different reaction paths considered have been fully characterized. The cluster-oxide surface interface has been found to involve the reduction of up to 3 Ce4+ to Ce3+, by direct electron transfer from the cluster to the oxide. When comparing the reducibility of the Ag-CeO2 and clean CeO2 systems, O vacancy formation has been found to be hindered along the perimeter of...

DOI: 10.1016/j.bmc.2019.05.011

Bioorganic & Medicinal Chemistry

The use of Photodynamic Therapy (PDT) for the treatment of several kinds of cancer as well as bacterial, fungal or viral infections has received increasing attention during the last decade. However, the currently clinically approved photosensitizers (PSs) have several drawbacks, including photobleaching, slow clearance from the organism and poor water solubility. To overcome these shortcomings, much effort has been made in the development of new types of PSs, such as Ru(II) polypyridyl complexes. Nevertheless, most studied Ru(II) polypyridyl complexes have a low absorbance in the spectral therapeutic window. In this work, we show that, by carefully selecting substituents on the polypyridyl complex, it is possible to prepare a complex absorbing at much higher wavelength. Specifically, we report on the synthesis and in-depth experimental and theoretical characterisation of a Ru(II) polypyridyl complex (complex 3) combining a s...

DOI: 10.1002/cptc.201900117

ChemPhotoChem

A tolane‐based molecule, the 4‐fluorophenyl 4‐((4‐(octyloxy)phenyl)ethynyl)‐benzoate (FOEB), was recently reported to show Crystallisation‐Induced Emission (CIE) and Aggregation‐Caused Quenching (ACQ) [Tong et al., J. Phys. Chem. C, 2015, 119, 21875]. In this work, we rely on a combination of tailored computational methods based on molecular dynamics, (TD‐)DFT and QM/QM’ calculations, to investigate the structural and optical properties of FOEB in solution, crystal and aggregate. First, the computation of the Huang‐Rhys factors and the reorganization energies can rationalize the modulation of the emission efficiency observed when changing the solvent polarity. The moderate fluorescence quenching observed in solution is due to the photophysical energy dissipation caused by low‐frequency vibrational modes involving the lateral groups along with motions out of the plane of the molecule. In crystalline environment, due to the packing arrangment, ther...

DOI: 10.1021/acs.jpcc.9b01047 

The Journal of Physical Chemistry

Oxide-carbonate composite electrolytes are complex materials whose peculiar conductivity performances are yet to be fully understood. Stability issues however arise when the carbonate is combined to an oxide such as TiO2, preventing practical fuel cell application of TiO2-based composites. To investigate the origin of such instability, a combined experimental and Density Functional Theory based approach is here presented and applied to the LiKCO3-TiO2 composite, focusing on energetic, electronic and vibrational properties. The origin of the instability of this composite could be traced back to the intrinsic reducible nature of TiO2, with inserted Li being almost fully oxidized and stabilized by reduced Ti atoms at the oxide surface, thus facilitating LixTiO2 phases formation and accumulation close to the interface between the oxide and the carbonate. This demonstrates that although the interface formation is critical for en...

DOI:10.1002/anie.201902456

Angewandte Chemie

Oxide-carbonate composite electrolytes are complex materials whose peculiar conductivity performances are yet to be fully understood. Stability issues however arise when the carbonate is combined to an oxide such as TiO2, preventing practical fuel cell application of TiO2-based composites. To investigate the origin of such instability, a combined experimental and Density Functional Theory based approach is here presented and applied to the LiKCO3-TiO2 composite, focusing on energetic, electronic and vibrational properties. The origin of the instability of this composite could be traced back to the intrinsic reducible nature of TiO2, with inserted Li being almost fully oxidized and stabilized by reduced Ti atoms at the oxide surface, thus facilitating LixTiO2 phases formation and accumulation close to the interface between the oxide and the carbonate. This demonstrates that although the interface formation is critical for enhanced conductivity...

DOI: 10.1039/C8CP07100D

Physical Chemistry Chemical Physics 2019

The excited state dynamics of constrained photochromic benzodithienylethenes were addressed by considering the bridging with polyether chains (from x = 4 to 6 units) at the ortho and meta positions of the aryl group, named DTE-ox and DTE-mx, via time-resolved absorption spectroscopy supported with (TD)-DFT calculations. The photochromic parameters and geometrical structures of these series are discussed. A novel photocyclization pathway via a triplet state, evidenced recently (Hamdi et al., Phys. Chem. Chem. Phys., 2016, 18, 28091–28100), is largely dependent on the length and the position of the polyether chain. For the first time, by comparing the two series, we revealed, for the DTE-ox series, an interconversion not only in the ground state but also between the triplet states of the anti-parallel and parallel open form conformers.

Synthesis

DOI:  10.1055/s-0037-1611673

A copper-catalysed hydroamination reaction of N-allenylsulfonamides with amines has been developed through a rational approach based on mechanistic studies. The reaction is promoted by a simple copper(I) catalyst and proceeds at room temperature with complete regioselectivity and excellent stereoselectivity towards linear (E)- N-(3-aminoprop-1-enyl)sulfonamides. Density Functional Theory (DFT) studies allow interpreting the key role of unsaturated substituents on nitrogen as ancillary coordinating moieties for the copper catalyst.

Journal of Computational Chemistry

DOI: 10.1002/jcc.25800

The ability to locate minima on electronic excited states (ESs) potential energy surfaces (PESs) both in the case of bright and dark states is crucial for a full understanding of photochemical reactions. This task has become a standard practice for small- to medium-sized organic chromophores thanks to the constant developments in the field of computational photochemistry. However, this remains a very challenging effort when it comes to the optimization of ESs of transition metal co

mplexes (TMCs), not only due to the presence of several electronic excited states close in energy, but also due to the complex nature of the excited states involved. In this article, we present a simple yet powerful method to follow an excited state of interest during a structural optimization in the case of TMC, based on the use of a compact hole-particle representation of the electronic transition, namely the natural transition orbitals (NTOs). State t...

The Journal of Physical Chemistry B 2019

DOI: 10.1021/acs.jpcb.8b10767

The RNA virus Influenza A is a serious public health problem with every year
epidemics resulting in more than 250,000 deaths. A protein cavity was identified
on the HA2 subunit of the hemagglutinin responsible for the entry of the virus into
the host cell by endocytosis. The binding of a ligand in this zone rich in invariant
residues and synthetic lethal couples, could prevent therapeutic escape and inhibit the
conformational change at pH=5 initiating the membrane fusion in the endosome. Two
pentapeptides, a linear peptide (EQRRS) and a cyclic peptide (DQRRD) have been
proposed as potential ligands. Complex stability and the interactions between the
ligand and the protein have been studied with the help of molecular dynamics and
quantum chemistry methods. A high stability of the interactions has been obtained
for these two ligands at both pH=7 and pH=5. Indeed, these two peptides present
two cooperative modes of actio...

Journal of Computational Chemistry 2018

DOI: 10.1002/jcc.25750 pdf

With the aim of offering new computational tools helping in the description of photochemical reactions and phenomena occurring at the excited state, we present in this work the capability of a density based index (Π) in locating decay channels from higher to lower excited states. The Π index, previously applied to disclose non‐radiative decay channels from the first excited state to the ground state, is very simple in its formulation and can be evaluated, practically with no extra computational cost, and coupled to any quantum method able to provide excited states densities. Indeed, this index relies only on the knowledge of energetics and electron densities of the different electronic states involved in the decay. In the present work, we show the proficiency of the Π index in the general case of decay between excited states by applying it to two model systems well characterized both theoretically and experimentally. In b...

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