New Polyether Macrocycles as Promising Antitumor Agents-Targeted Synthesis and Induction of Mitochondrial Apoptosis

A series of previously unknown aromatic polyether macrodiolides containing a cis,cis-1,5-diene moiety in the molecule were synthesized in 47-74% yields. Macrocycle compounds were first obtained by intermolecular esterification of aromatic polyether diols with α,ω-alka-nZ,(n+4)Z-dienedioic acids mediated by N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC·HCl) and 4-(dimethylamino)pyridine (DMAP). For the synthesized compounds, studies of cytotoxicity on tumor (Jurkat, K562, U937), conditionally normal (HEK293) cell lines, and normal fibroblasts were carried out. CC50 was determined, and the therapeutic selectivity index of cytotoxic action (SI) in comparison with normal fibroblasts was evaluated. With the involvement of modern methods of flow cytometry for the most promising macrocycles, their effect on mitochondria and the cell cycle was investigated. It was found that a new macrocycle exhibits pronounced apoptosis-inducing activity toward Jurkat cells and can retard cell division by blocking at the G1/S checkpoint. Also, it was shown that the synthesized macrodiolides influence mitochondria due to their high ability to penetrate the mitochondrial membrane.

Energy Decomposition Scheme for Rectangular Graphene Flakes

We show-to our own surprise-that total electronic energies for a family of m × n rectangular graphene flakes can be very accurately represented by a simple function of the structural parameters m and n with errors not exceeding 1 kcal/mol. The energies of these flakes, usually referred to as multiple zigzag chains Z(m,n), are computed for m, n < 21 at their optimized geometries using the DFTB3 methodology. We have discovered that the structural parameters m and n (and their simple algebraic functions) provide a much better basis for the energy decomposition scheme than the various topological invariants usually used in this context. Most terms appearing in our energy decomposition scheme seem to have simple chemical interpretations. Our observation goes against the well-established knowledge stating that many-body energies are complicated functions of molecular parameters. Our observations might have far-reaching consequences for building accurate machine learning models.

Tracing the transition from covalent to non-covalent functionalization of pyrene through C-, N-, and O-based ionic and radical substrates using quantum mechanical calculations

Pyrene is one of the widely investigated aromatic hydrocarbons given its unique optical and electronic properties. Modulating inherent characteristics of pyrene via covalent or non-covalent functionalization has been attractive for a wide variety of advanced biomedical and other device applications. In this study, we have reported the functionalization of pyrene via C, N, and O based ionic and radical substrates, and emphasized the transition of covalent to non-covalent functionalization through making the modulation in the substrate. As expected, strong interactions were observed for cationic substrates, however, anionic substrates also exhibited a competitive binding strength. For instance, methyl and phenyl substituted CH₃ complexes exhibited IEs in the range of -17 kcal mol^-1 to -127 kcal mol^-1 and -14 kcal mol^-1 to -95 kcal mol^-1 and for cationic and anionic substrates, respectively. The analysis of topological parameters showed that un-substituted cationic, anionic, and radical substrates interact with pyrene via covalent interactions, and further become non-covalent upon methylation and phenylation of the substrates. In cationic complexes, the polarisation component is observed to be dominating the interactions, whereas highly competitive contributions from polarization and exchange components were observed in anionic and radical complexes. The contribution of the dispersion component increases with an increase in the degree of methylation and phenylation of the substrate, and starts dominating once the interactions become non-covalent in nature.

A general tight-binding based energy decomposition analysis scheme for intermolecular interactions in large molecules

In this work, a general tight-binding based energy decomposition analysis (EDA) scheme for intermolecular interactions is proposed. Different from the earlier version [Xu et al., J. Chem. Phys. 154, 194106 (2021)], the current tight-binding based density functional theory (DFTB)-EDA is capable of performing interaction analysis with all the self-consistent charge (SCC) type DFTB methods, including SCC-DFTB2/3 and GFN1/2-xTB, despite their different formulas and parameterization schemes. In DFTB-EDA, the total interaction energy is divided into frozen, polarization, and dispersion terms. The performance of DFTB-EDA with SCC-DFTB2/3 and GFN1/2-xTB for various interaction systems is discussed and assessed.

Nature of hydride and halide encapsulation in Ag8 cages: insights from the structure and interaction energy of [Ag8(X){S2P(OiPr)2}6]+ (X = H-, F-, Cl-, Br-, I-) from relativistic DFT calculations

Unraveling the different contributing terms to an efficient anion encapsulation is a relevant issue for further understanding of the underlying factors governing the formation of endohedral species. Herein, we explore the favorable encapsulation of hydride and halide anions in the [Ag₈(X){S₂P(OPr)₂}₆]⁺ (X^- = H, 1, F, 2, Cl, 3, Br, 4, and, I, 5) series on the basis of relativistic DFT-D level of theory. The resulting Ag₈-X interaction is sizable, which decreases along the series: -232.2 (1) > -192.1 (2) > -165.5 (3) > -158.0 (4) > -144.2 kcal mol^-1 (5), denoting a more favorable inclusion of hydride and fluoride anions within the silver cage. Such interaction is mainly stabilized by the high contribution from electrostatic type interactions (80.9 av%), with a lesser contribution from charge-transfer (17.4 av%) and London type interactions (1.7 av%). Moreover, the ionic character of the electrostatic contributions decreases from 90.7% for hydride to 68.6% for the iodide counterpart, in line with the decrease in hardness according to the Pearson's acid-base concept (HSAB) owing to the major role of higher electrostatic interaction terms related to the softer (Lewis) bases. Lastly, the [Ag₈{S₂P(OPr)₂}₆]²⁺ cluster is able to adapt its geometry in order to maximize the interaction towards respective monoatomic anion, exhibiting structural flexibility. Such insights shed light on the physical reasoning necessary for a better understanding of the different stabilizing and destabilizing contributions related to metal-based cavities towards favorable incorporation of different monoatomic anions.

Coinage-metal pillarplexes hosts. Insights into host-guest interaction nature and luminescence quenching effects

Host-guest chemistry is a relevant issue in materials science, which encourages further development of versatile host structures. Here the particular features of coinage-metal pillarplexes are evaluated towards formation of host-guest aggregates by the inclusion of 1,8-diaminooctane, as characterized for [M8(LMe)2]4+ (M = Ag, and, Au). The obtained results denotes the main contribution from van der Waals type interaction (50%), followed by a contribution from orbital polarization and electrostatic nature (20% and 30%), involving both orbitalary and electrostatic terms. Throughout the different coinage-metal based hosts (M = Cu, Ag, and Au), a similar interaction energy is found given by the large contribution of the π-surface from the organic ligand backbone to both van de Waals and electrostatic interactions. This suggests that a similar host structure can be obtained for the lighter copper counterpart, retaining similar how-guest features. Moreoves, the [Au8(LMe)2]4+ host exhibits inherent luminescent properties, involving the shortening of Au(i)-Au(i) contacts at the excited state, which is partially avoided when the guest is incorporated, accounting for the observed quenching from titration experiments. This results encourages further exploration of coinage metal hosts in the formation of inclusion complexes.