A systematic study on bis(dicyclooctatetraenyl)diuranium (U 2 COT 4 ) has been performed using relativistic density functional theory. The molecule was calculated in four different electronic configurations and the two symmetries C 2 and D 2h . First we considered the high-spin quintuplet ( 5 A) state, and from this state we built the broken-symmetry configuration following Noodleman's approach. Also, the triplet state was considered as a formal interaction of both uranocene fragments in triplet and singlet states simultaneously, and finally the low-spin singlet configuration was calculated. For both symmetries the ground state of the complex was the quintuplet, and on the basis of the broken-symmetry approach a significant ferromagnetic coupling between both metals was found. Time-dependent density functional theory (TDDFT) was used to calculate the excitation energies with the GGA SAOP functional. The obtained electronic transitions are in good correlation with reported experimental values, which are found between 600 and 720 nm: 633, 658, 664, 673, 685, and 717 nm.

The rarely recognized electron donating ability of the benzophenone triplet excited state provides an unusual route for the photochemical synthesis of gold nanoparticles.

Phosphofructokinases catalyze the ATP-dependent phosphorylation of fructose-6-phosphate and they are highly regulated.

A systematic study of a series of An(COT)(2) compounds, where An = Th, Pa, U, and COT represents cyclooctatetraene, has been performed using relativistic density functional theory. The ZORA Hamiltonian was applied for the inclusion of relativistic effects, taking into account all of the electrons for the optimization and explicitly including spin-orbit coupling effects. Time-dependent density functional theory (TDDFT) was used to calculate the excitation energies with the GGA SAOP functional, and the electronic transitions were analyzed using double group irreducible representations. The calculated excitation energies are in perfect correlation with the increment of the ring delocalization as it increases along the actinide series. These results are sufficient to ensure that, for these complexes, the increment in delocalization, as indicated by ELF bifurcation and NICS analysis, leads to a shift in the maximum wavelength of absorption in the visible region. Also, delocalization in the COT ring increases along the actinide series, so the systems become more aromatic because of a modulation induced by the actinides.

The high interest in lanthanide chemistry, and particularly in their luminescence, has been encouraged by the need of understanding the lanthanide chemical coordination and how the design of new luminescent materials can be affected by this. This work is focused on the understanding of the electronic structure, bonding nature, and optical properties of a set of lanthanide hexaaza macrocyclic complexes, which can lead to potential optical applications. Here we found that the DFT ground state of the open-shell complexes are mainly characterized by the manifold of low lying f states, having small HOMO-LUMO energy gaps. The results obtained from the wave function theory calculations (SO-RASSI) put on evidence the multiconfigurational character of their ground state and it is observed that the large spin-orbit coupling and the weak crystal field produce a strong mix of the ground and the excited states. The electron localization function (ELF) and the energy decomposition analysis (EDA) support the idea of a dative interaction between the macrocyclic ligand and the lanthanide center for all the studied systems; noting that, this interaction has a covalent character, where the d-orbital participation is evidenced from NBO analysis, leaving the f shell completely noninteracting in the chemical bonding. From the optical part we observed in all cases the characteristic intraligand (IL) (π-π*) and ligand to metal charge-transfer (LMCT) bands that are present in the ultraviolet and visible regions, and for the open-shell complexes we found the inherent f-f electronic transitions on the visible and near-infrared region.

Since the synthesis of the first molecular cluster [Re6(μ3-Q8)X6](4-), the substitutional lability of the terminal ligands prompted new developments in their chemistry, making these molecular clusters a reasonable point of departure for building new materials. The development of novel inorganic materials of technological interest certainly requires an understanding of the electronic structure, bonding, spectroscopy, photophysical and structural properties of these clusters. Taking into account the potential applications in material sciences and the lack of systematization in the study of these kinds of clusters, the proposal of the present work is to perform a detailed theoretical study of the [Re6(μ3-Q8)X6](4-) (Q = S(2-), Se(2-), Te(2-); X = F(-), Cl(-), Br(-), I(-), CN(-), NC(-), SCN(-), NCS(-), OCN(-), NCO(-)) clusters based on the detailed description of the electronic structure of these complexes and the bonding nature between the [Re6(μ3-Q8)](2+) core and several donor-acceptor peripheral ligands. All this work was developed on the framework of the relativistic density functional theory, in which relativistic effects were incorporated by means of a two-component Hamiltonian with the zeroth-order regular approximation. To describe the relative stability of these complexes, we employed the global descriptors of chemical hardness and softness introduced by Pearson. Moreover, an analysis of bonding energetics was performed by combining a fragment approach to the molecular structure with the decomposition of the total bonding energy according to the Morokuma-Ziegler energy partitioning scheme. After an analysis of these results, we found in all cases an extensive ionic character in the bonding between the core and each peripheral ligand. The interaction between the halide ligand and the core gives about 75% ionic character, whereas the other ligands show a more covalent interaction due to effective synergic mechanisms. We conclude that the most stable clusters are those that present the stronger σ-donor terminal ligands, whereas the cluster stability starts to decrease when the π-acceptor effect will be stronger; this fact is directly related to the terminal ligand lability and the strong electrophilic character of the [Re6(μ3-Q8)](2+) core.

The zinc metallopeptidase Pseudomonas elastase (LasB) is a virulence factor of Pseudomonas aeruginosa (P. aeruginosa), a pathogenic bacterium that can cause nosocomial infections. The present study relates the structural analysis of 118 N-alpha-mercaptoacetyl dipeptides (NAMdPs) as LasB inhibitors. Field-based 3D-QSAR and molecular docking methods were employed to describe the essential interactions between NAMdPs and LasB binding sites, and the chemical features that determine their differential activities. We report a predictive 3D-QSAR model that was developed according to the internal and external validation tests. The best model, including steric, electrostatic, hydrogen bond donor, hydrogen bond acceptor, and hydrophobic fields, was found to depict a three-dimensional map with the local positive and negative effects of these chemotypes on the LasB inhibitory activities. Furthermore, molecular docking experiments yielded bioactive conformations of NAMdPs inside the LasB binding site. The series of NAMdPs adopted a similar orientation with respect to phosphoramidon within the LasB binding site (crystallographic reference), where the backbone atoms of NAMdPs are hydrogen-bonded to the LasB residues N112, A113, and R198, similarly to phosphoramidon. Our study also included a deep description of the residues involved in the protein–ligand interaction patterns for the whole set of NAMdPs, through the use of interaction fingerprints (IFPs).

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