In Silico Analysis of the Aromaticity of Some Carbo-Metallabenzenes and Carbo-Dimetallabenzenes (Carbo-mers Proposed from Metallabenzenes).

In the current work, we introduce a novel class of molecules termed carbo-metallabenzenes, and their aromaticity has been comprehensively analyzed. The molecules were strategically designed with the insertion of acetylene (C≡C or C2) units in some selected metallabenzenes. Furthermore, if a second metallic unit is inserted (replacing a sp2 carbon) in the carbo-metallabenzenes rings, a new family of carbo-mers is generated, and this second group has been named as carbo-dimetallabenzenes. The primary objective of this work is to ascertain, through various methodologies, whether these newly proposed molecules retain the aromatic characteristics observed in carbo-benzene. The methodologies employed for bond analysis and aromaticity exploration include the analysis of the molecular orbitals, energy decomposition analysis, electron density of delocalized bonds, magnetically induced current density, and the induced magnetic field (Bind). This study sheds light on that the insertion of the metallic centers reduces the electronic delocalization and their aromaticity is, in some cases, comparable with the electronic delocalization of the inorganic iminobora-borazine and also provides valuable insights into their electronic structure through a multifaceted analysis.

Metallaborazines: To Be or Not To Be Delocalized.

In the current work, the analysis of the electronic delocalization of some metallacycles, based on borazine, was realized by employing magnetic criteria, such as the induced magnetic field and magnetically induced current densities, and electronic criteria, such as adaptative natural density partitioning and the analysis of molecular orbitals. The current metallaborazines were generated from isoelectronic substitutions. The main question is whether the electronic delocalization increases or decreases. The results showed that metal-N bonded borazines could be cataloged as delocalized compounds. On the other hand, the metal-B bonded borazines could be cataloged as nonaromatic (or weak aromatic) compounds based on the results of this analysis.

Correction to "In Silico Analysis of the Electronic Delocalization in Some Double Fused-Ring Metallabenzenes".

[This corrects the article DOI: 10.1021/acsomega.1c00632.].

In Silico Analysis of the Electronic Delocalization in Some Double Fused-Ring Metallabenzenes.

In the current work, some metallabenzenes with one and several fused rings were analyzed in terms of their electronic delocalization. These fused-ring metallabenzenes are known as metallabenzenoids, and their aromatic character is not free of controversy. The systems of the current work were designed from crystallographic data of some synthesized molecules, and their electronic delocalization (aromaticity) was computationally examined in terms of the molecular orbital analysis (Hückel's rule), the induced magnetic field, and ring currents. The computational evidence allows us to understand if these molecules are or are not aromatic compounds.

Analysis of the electronic delocalization in some isoelectronic analogues of B12 doped with beryllium and/or carbon.

In the current work, a new family of isoelectronic analogues to B12 is reported. The construction of this family was performed through the isoelectronic substitution principle to generate species such as B11C+, B11Be-, B10BeC, B10C22+, B10Be22- B9Be2C-, and B9BeC2+. The search for the global minimum was realized by utilizing genetic algorithms, while the induced magnetic field, electronic localization function, magnetic current densities, and multicenter aromaticity criteria were calculated to understand their electronic delocalization. Our results show that, in general, C atoms avoid hypercoordination, whereas we have found species with Be atoms located in hypercoordinated positions that are relatively stable. Our analysis of aromaticity indicates that B12 has double σ and π disk aromaticity. Mono, double or triple substitution of B by C+ or Be- reduces somewhat the aromaticity of the clusters, but less in the case of Be- substitution.

NCI-ELMO: A New Method To Quickly and Accurately Detect Noncovalent Interactions in Biosystems.

Accurate determinations of noncovalent interactions in biological systems are fundamental to rationalize the structure and to get insights into the functions and the dynamics of macromolecules. Here we propose a new tool for the efficient identification of noncovalent interactions in proteins. The noncovalent interaction (NCI) method, a well-established strategy to detect noncovalent interactions in chemical systems, is coupled with the libraries of extremely localized molecular orbitals (ELMOs), which allow instantaneous reconstruction of quantum mechanically rigorous electron distributions of polypeptides and proteins. Test calculations performed on different interactions show that the new NCI-ELMO strategy always outperforms the original NCI method based on the promolecular approximation, while it is in close agreement with original NCI analyses based on fully quantum mechanical calculations. The new technique allows for unraveling the network of interactions in biological systems and to rapidly monitor their evolutions with time, with possible consequences on the design of new drugs.

Effects of the acceptor unit in dyes with acceptor-bridge-donor architecture on the electron photo-injection mechanism and aggregation in DSSCs.

Dye-sensitized solar cells (DSSCs) are devices that convert light to electrical energy. Nowadays, researchers have focused on the understanding of the performance of dyes in solar cells. In this way, new efficient dyes have been obtained which can act as efficient light-harvesting compounds where the combination and the balance of acceptor(A)-bridge-donor(D) architectures confer suitable attributes and properties to the dye. Herein, we have carried out a DFT study on the optical and electronic properties of eight different A motifs and their influence on the electron photo-injection (PI) mechanisms through type I (indirect) or type II (direct) pathways in A-bridge-D dyes in DSSCs. The models consisted of thiophene as a bridge and triphenylamine as a D anchored to a TiO2 anatase cluster. All geometry optimizations were calculated using the B3LYP, CAM-B3LYP and BHandHLYP functionals combined with the 6-31G(d,p) basis set for C, H, N, O and S and the LANL2DZ pseudopotential for Ti atoms. Most of the A dyes display optoelectronic properties consistent with a type-I (indirect) mechanism except for the A5 dye where the results suggest a type-II (direct) PI pathway. In addition, molecular dynamics (MD) simulations have been carried out in order to describe the formation of dye dimers and analyze the stability of the aggregates due to intermolecular interactions. The observed trends indicate that dyes with A2 and A5 anchoring groups have less tendency to dimerize due to weaker intermolecular interactions resulting in less stable dimer complexes. Specifically, we found that the A motif influences the PI by a dye and the dimerization profiles.