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Substituting the O-C2H4-O-moiety of [2.2.2] by the O2CCO2-core of oxalic acid leads to the new Lehn-type cryptand [M ⊂ 2Oxa.2Oxa.2Oxa]m+. We explored by quantum chemical methods (B3LYP/LANL2DZp) the complexation behaviour and compared it with the original cryptand [2.2.2]. The cryptands [2Oxa.2Oxa.2Oxa] and [2.2.2] exhibit the same ion selectivity against alkaline and alkaline earth metal cation (K+ followed by Rb+; Ba2+ preferred over Sr2+). The exchange of the OC2H4O-moiety by the O2CCO2-moiety (the subsequent exchange of sp3- by sp2-carbon atoms) makes [2Oxa.2Oxa.2Oxa] less flexible in the OCCO-diether angle as [2.2.2]. This rigidity results in higher complexation energies for [M ⊂ 2Oxa.2Oxa.2Oxa]m+ and that the twisting of the dihedral angle CN...NC improves the nesting of the guest cations in the cryptand [2Oxa.2Oxa.2Oxa]. [ABSTRACT FROM AUTHOR]

The cryptand developed by Virgil L. Goedken and Shie-Ming Peng, along with its interactions with alkaline and alkaline earth metal ions, was investigated using computational chemistry (B3LYP/LANL2DZp) to gain insight into the influence of the flexibility of the chelating N-C-C-N group on overall selectivity towards metal ions. According to DFT calculations, the most suitable cation for the cryptand is Li+, as Na+ is too large and would prefer a longer bond between Na+ and the N-donor. Additionally, the Be2+-N bond in the Goedken-Peng cryptand is excessively long compared to the Mg2+-N-cryptate bond, which is too short. The most effective method for hosting the guest cations is for the cryptand to twist itself, and the flexibility of the chelating N-C-C-N group serves as the most effective structural motive for the Goedken-Peng cryptand to interact with the guest cation. [ABSTRACT FROM AUTHOR]

The interaction of dibutyltin(IV) dichloride (DBT) with 1,4-diazacycloheptane (homopiperazine, HP) was investigated. In solutions, the complexes formed a 1:1 complex, its protonated and hydrolyzed forms. The formation constants of the complexes and thermodynamic parameters as ΔH° and ΔS° were estimated. The optimization of the structure of the (Bu)2Sn(HP)Cl2 complex reveals that the tin is six-coordinate in a distorted octahedral geometry, where the two nitrogen atoms of homopiperazine and the two chloride ions are in one plane. The solid (Bu)2Sn(HP)Cl2 complex with homopiperazine was synthesized, and the composition was assigned by elemental micro-analysis and mass spectrum. The complex was investigated by infrared, mass spectra, and thermal measurements. The ligand and its complex were tested against antimicrobial Staphylococcus aureus (+ve), Escherichia coli (−ve), and antifungal Candida albicans and Aspergillus flavus. Anticancer activities of homopiperazine and its dibutyltin(IV) complex were tested against breast cancer cell lines. The molecular docking investigations were performed to know the possible modes of binding to the most active sites of the breast cancer oxidoreductase receptor and those of Escherichia coli. [ABSTRACT FROM AUTHOR]

Selective alkaline and earth alkaline metal ion encapsulation by six different Lehn-type cryptands was predicted by DFT (B3LYP/LANL2DZp) computational chemistry. All cryptands contain three identical moieties connected by the aliphatic nitrogen atom, constructing a very structurally flexible system for accommodating different-sized metal cations. Inspiration for selected hosts was taken from already well-known Lehn-type Cryptand [phen.phen.phen] where one phenanthroline was substituted by 5H-cyclopenta[2,1-b:3,4b′]pyridine in which the CH2– group was replaced by a series of heteroatoms forming the selected series of investigated hosts. The ion selectivity and the ability of the hosts to adjust their structure to accommodate the metal cations successfully were based on energy and geometric criteria. Medium-size cations have been proven to be best fitted for the selected host series. [ABSTRACT FROM AUTHOR]

Based on computational chemistry calculations (ωB97XD/def2‐tzvp//ωB97XD/def2‐svp/svpfit+ZPE(ωB97XD/def2‐svp/svpfit)), binding energy of tubular[3,6,6,6]arene to accommodate noble gases and a series of 29 small gases were calculated. Based on the gained results, Rn (−17.52 kcal/mol) from the series of noble gases is best suited to be accommodated. In the series of noble gases, the binding energy increases linearly with increasing gas radii. From the series of 29 small guests, IF3 and C2I2 (~ −23 kcal/mol) have the best proclivity to be most effectively accommodated in the tubularene, with other 26 exhibiting favorable encapsulation energies on various scales depending on their voluminosity and structure, and only NI3 with the unfavorable complexation energy of 13.87 kcal/mol. Investigated gases, depending on the size, are placed at the different position inside the tube‐like cavity of the tubularene. The structure of the tubularene, independent of the hosted guest species, has remained very rigid, with its atom's rearrangements withing an error margin. [ABSTRACT FROM AUTHOR]