Heterotopic mechanically interlocked molecules contain different binding sites within their structure, allowing them to recognize specific ion pairs (cations and anions) with a high affinity. The employment of heteroditopic receptors offers advantages over monotopic analogues, in general, being composed of both cation and anion binding sites. The present study elucidates the electronic structure-based recognition of anions and cations of a heteroditopic [2]catenane, IO. Spherical cations and anions have been employed. The structure of IO was modified by replacing its original oxygen atoms of the crown-ether moiety by sulfur atoms and σ-hole donor iodines by -Te-CH3 groups leading to the modified [2]catenanes IS and TeO, respectively. Energy decomposition analysis (EDA) and natural orbital for chemical valence reveals that the cations exhibit the strongest interaction with the binding pockets of all structures, with Cu+, Li+, and Ni2+ presenting the most stabilizing values, ΔEIOtot = -198.2, -175.1, and -653.4 kcal·mol-1, and ΔEIStot= -226.4, -154.0, -702.5 kcal·mol-1, respectively. In contrast, anion recognition presented to be significantly lower, being purely dependent on the strength of the σ-hole donors and the size of the applied anion, with Cl- exhibiting the most stable interaction, where ΔEIOtot = -109.9 kcal·mol-1. It was also found that the anion recognition for this particular molecule does not affect the cation recognition, significantly. The EDA results confirm that changing from a harder (O) to a softer (S) interactive environment will have considerable impact on cation recognition, thereby demonstrating the pivotal role, following the size match rule.
Superatoms are clusters with physical or chemical properties that bear certain similarities to atoms. We calculated equilibrium geometries and properties using spin-polarized density functional theory (DFT) within the generalized gradient approximation (PBE). We also performed Ab Initio Molecular Dynamics (AIMD) simulations in the NVT ensemble with a Nosé-Hoover thermostat. In addition, Monte Carlo simulations with a potential fitted to DFT were carried out to assess a number of clusters as possible superatoms. The clusters we studied have a chemical composition AB2C10, where A, B, and C are metals, and a structure derived from that of a 13-atom icosahedron. We adopt an operational definition of superatom to assess clusters. According to this definition, superatoms should have (i) a quasispherical equilibrium geometry and (ii) a set of valence orbitals delocalized over the cluster; (iii) they should maintain these two attributes at elevated temperatures (mechanical and thermal stability); and (iv) they should be thermodynamically favored relative to similar clusters. By these criteria, Sn3Y10, CrSn2Zr10, and possibly CrSn2Ti10 can be classified as "superatoms". We show that cluster stability arises from (i) the intrinsic stability of the C10 fragment; (ii) its interaction energy with the three "dopant atoms"; and (iii) compatible atomic sizes of the three elements. Clusters such as CrSn2Ti10 and CrSn2Zr10 exhibit an optimal balance among these contributions. They have a high effective coordination, an absence of very low vibrational frequencies, a favorable ratio of their elements' cohesive energy, and exceptional thermal resilience, with melting temperatures that are well above the weighted average of their elements' bulk melting points. Electronic analysis shows that CrSn2Ti10 and CrSn2Zr10 display discrete density-of-states features and partial electron delocalization, consistent with superatomic behavior. These electronic properties vanish as the clusters approach the melting point and undergo structural distortion. We show the importance of looking at several, often interrelated, properties in assessing possible superatoms.
Breast cancer (BC) is one of the most challenging types of cancer in women. Triple-negative breast cancer (TNBC) is an aggressive and rapidly progressive subtype that lacks targeted therapies, relying primarily on chemotherapy. Given the limited treatment options for TNBC, novel therapeutic strategies are needed to address this disease. In this context, here we report the synthesis and characterization of four ruthenium(II) complexes containing naphthoquinone derivatives as ligands: [Ru(NQ1)(bipy)(dppen)]PF6 (Ru1), [Ru(NQ2)(bipy)(dppen)]PF6 (Ru2), [Ru(NQ1)(bipy)(DPEphos)]PF6 (Ru3), and [Ru(NQ2)(bipy)(DPEphos)]PF6 (Ru4), where bipy = 2,2'-bipyridine, dppen = 1,2-bis(diphenylphosphino)ethylene, DPEphos = bis[(2-diphenylphosphino)phenyl]ether, and NQ1 and NQ2 = deprotonated lawsone and lapachol, respectively. Mass spectrometry and elemental analyses were used to confirm the purity of the complexes. In vitro assays showed that Ru1-Ru4 were cytotoxic against MDA-MB-231 and MCF-7 (breast cancer cell lines) and A549 (lung cell line). The compounds exhibited lower IC50 values than cisplatin, used as a control. Ru4 was the most promising compound, with the highest selectivity index for the triple-negative breast cancer cell line (SI = 25.5). Furthermore, this complex inhibited colony formation, induced apoptosis, and affected the cell cycle in these cancer cells. Western blot analysis showed increased cleaved caspase-3 expression, corroborating the apoptotic mechanism observed by flow cytometry. Furthermore, cell uptake studies showed that ruthenium was found at the intracellular level after treatment with the MDA-MB-231 cell line. DNA-binding studies revealed an interaction between Ru1-Ru4 and Ct-DNA via the minor groove pocket, as confirmed by molecular docking. Overall, our results suggest [Ru(NQ2)(bipy)(DPEphos)]PF6 (Ru4) to be a promising cytotoxic agent against breast cancer.
The misunderstanding of adolescence has had a direct impact on the creation of public policies that directly serve this population. The aim of this study was to understand how socio-education takes place between the guarantee of rights and the social vulnerabilities that exist in the territory. This section of the research involves the development of six focus groups with twelve adolescent participants, as well as a semi-structured interview with family members. The content was analyzed using pre-established categories and subcategories obtained after data collection. It was pointed out that offending should be seen as a multifactorial cause, motivated mainly by social disenfranchisement and the absence of a clear and effective system for guaranteeing rights, which includes all public policies.
