Modeling Photonastic Materials: A First Computational Study.

Photonastic materials present a directional and repeatable deformation of the material shape due to transduction from light energy to mechanical energy. Among these materials, light-responsive polymers, composed of photochromic molecules embedded in a polymer matrix, are of high interest. The present work aims at laying the foundation stone of the modeling of the photomechanical behavior of such systems by proposing a computational strategy that is able to investigate (i) the impact of the polymer matrix on the photochromic properties of a dithienylethene (DTE) switch and (ii) the impact of the photochromic reaction on the polymer environment.

Development of Theranostic Cationic Liposomes Designed for Image-Guided Delivery of Nucleic Acid.

Cationic liposomes have been considered as potential vectors for gene delivery thanks to their ability to transfect cells with high efficiency. Recently, the combination of diagnostic agent and therapeutic agents in the same particle to form a theranostic system has been reported. Magnetic liposomes are one of these examples.

Range-separated hybrid and double-hybrid density functionals: A quest for the determination of the range-separation parameter.

We recently derived a new and simple route to the determination of the range-separation parameter in range-separated exchange hybrid and double-hybrid density functionals by imposing an additional constraint to the exchange-correlation energy to recover the total energy of the hydrogen atom [Brémond et al., J. Chem.

General Density-Based Index to Analyze Charge Transfer Phenomena: From Models to Butterfly Molecules.

We present a new formula and implementation for a descriptor enabling quantification of the electron-hole distance associated with a charge transfer of an optical transition, on the basis of the knowledge of the densities of the electronic ground and excited states. This index is able to define a charge-transfer length even for systems that would be otherwise difficult to treat, like symmetric molecules, while maintaining a very low computational cost and the possibility to be coupled to any method providing ground and excited state electron densities. After a benchmark of its performance on a series of push-pull molecules, the index has been applied to a set of large symmetric luminophores, the so-called "butterfly molecules", showing promising applications in optoelectronics, to highlight its potential use in the design of new compounds.

Toward the Mechanistic Understanding of the Additives' Role on Ammonium Nitrate Decomposition: Calcium Carbonate and Calcium Sulfate as Case Studies.

The reaction mechanism involved in the decomposition of ammonium nitrate (AN) in the presence of CaCO and CaSO, commonly used for stabilization and the reduction of explosivity properties of AN, was theoretically investigated using a computational approach based on density functional theory. The presented computational results suggest that both carbonate and sulfate anions can intercept an acid proton from nitric acid issued from the first step of decomposition of AN, thus inhibiting its runaway decomposition and the generation of reactive species (radicals). The reaction then leads to the production of stable products, as experimentally observed.

Understanding the properties of dithienylethenes functionalized for supramolecular self-assembly: a molecular modeling study.

A dithienylethene (DTE) photochromic compound functionalized by ureidopyrimidinone (UPy) quadruple hydrogen bonding blocks was synthesized by Takeshita and coworkers [Takeshita et al., Chem. Commun.

Construction of 1-Tetralols Bearing Two Contiguous Quaternary Chiral Centers through a Rhodium-Catalyzed Enantioselective Desymmetrization Cascade Reaction.

A novel and efficient access to polyfunctionnalized chiral 1-tetralols, bearing two contiguous quaternary carbon stereocenters, has been developed from various and easily accessible alkynyl-1,3-diketones, through a cascade process including a regioselective alkyne insertion, a 1,4-Rh shift, and a nucleophilic addition step via the desymmetrization of the 1,3-diketone moiety thanks to an appropriate rhodium-chiral diene complex in the presence of arylboronic acids.

Iron-Catalyzed Cross-Coupling of -(aryl)manganese Nucleophiles with Alkenyl Halides: Optimization and Mechanistic Investigations.

Various substituted -(aryl)manganese species were prepared from aryl bromides by one-pot insertion of magnesium turnings in the presence of LiCl and in situ trans-metalation with MnCl in THF at -5 °C within 2 h. These -(aryl)manganese reagents undergo smooth iron-catalyzed cross-couplings using 10 mol% Fe(acac) with various functionalized alkenyl iodides and bromides in 1 h at 25 °C. The aryl-alkenyl cross-coupling reaction mechanism was thoroughly investigated through paramagnetic H-NMR, which identified the key role of -coordinated -iron(II) species in the catalytic process.

Spectroscopic and Microscopic Analyses of FeO/Au Nanoparticles Obtained by Laser Ablation in Water.

Magneto-plasmonic nanoparticles constituted of gold and iron oxide were obtained in an aqueous environment by laser ablation of iron and gold targets in two successive steps. Gold nanoparticles are embedded in a mucilaginous matrix of iron oxide, which was identified as magnetite by both microscopic and spectroscopic analyses. The plasmonic properties of the obtained colloids, as well as their adsorption capability, were tested by surface-enhanced Raman scattering (SERS) spectroscopy using 2,2'-bipyridine as a probe molecule.

sp-hybridized carbon allotrope molecular structures: An ongoing challenge for density-functional approximations.

The recent synthesis of a C monocyclic ring constitutes a major breakthrough as a new all-carbon disclosed form. However, modern density functional theory approaches do not lead to the correct experimental polyynic structure and favor the cumulenic one instead. We demonstrate here that this serious drawback can be solved by recently developed range-separated nonempirical schemes, independently of which kind of functional is being applied (i.

Aggregation Effects on Pigment Coatings: Pigment Red 179 as a Case Study.

Here, we have studied, with a combined experimental and computational approach, the effect of the crystal environment and aggregation on the electronic properties of Pigment Red 179, which affect both its color and optical energy gap. Spectra acquired in the near-infrared and visible range of energies suggest that this molecule is indeed a "cool" dye, which can be employed as a red pigment that provides effective color coverage to different substrates without contributing to their heating during light irradiation. Spectra acquired on different polymer mixtures at different pigment concentrations (i.

Synthetic, Structural, and Anticancer Activity Evaluation Studies on Novel Pyrazolylnucleosides.

The synthesis of novel pyrazolylnucleosides -, -, -, and - are described. The structures of the regioisomers were elucidated by using extensive NMR studies. The pyrazolylnucleosides - and - were screened for anticancer activities on sixty human tumor cell lines.

Enantioenriched 1-Tetralones via Rhodium-Catalyzed Arylative Cascade Desymmetrization/Acylation of Alkynylmalonates.

An efficient atom-economic rhodium-catalyzed asymmetric arylative cyclization to access enantioenriched 1-tetralones, bearing a quaternary carbon stereocenter, is described, involving a highly regioselective alkyne insertion, a 1,4-Rh shift, and an acylation step via the desymmetrization of the malonate moiety thanks to an appropriate chiral diene ligand.

Range-separated hybrid density functionals made simple.

In this communication, we present a new and simple route to derive range-separated exchange (RSX) hybrid and double hybrid density functionals in a nonempirical fashion. In line with our previous developments [Brémond et al., J.

Chiral Bicyclo[2.2.2]octa-2,5-dienyltrifluoroborate Derivative as a Useful and Stable Precursor of C-Symmetric Chiral Dienes.

A new approach has been developed to prepare monosubstituted C-symmetric chiral dienes Ar-MSBod from easily accessible chiral bicyclo[2.2.2]octa-2,5-dienyltrifluoroborate derivative.

From Tetrahydrofurans to Tetrahydrobenzo[ d]oxepines via a Regioselective Control of Alkyne Insertion in Rhodium-Catalyzed Arylative Cyclization.

The formation of chiral 5- and 7-membered tetrahydrofurans and tetrahydrobenzo[ d]oxepines is achieved via arylative cyclization of simple O-tethered alkyne-enoates in the presence of arylboronic acids and chiral dienes-rhodium catalyst under mild conditions. Access to such structures was achieved via a simple switch in the regioselectivity of the alkyne insertion thanks to a proper choice of the alkyne substituent.

Excited state tracking during the relaxation of coordination compounds.

The ability to locate minima on electronic excited states (ESs) potential energy surfaces 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 complexes (TMCs), not only due to the presence of several electronic ESs close in energy, but also due to the complex nature of the ESs involved.