Stereoselective Self-Assembly of a Topologically Chiral [6]Catenane with 18 Crossings.

Mechanically interlocked molecules (MIMs) exhibit unique properties and functions arising from their structural entanglement, features of which are absent in their individual components. However, synthesizing topologically complex architectures, particularly those with topological chirality, remains a significant challenge due to the lack of general methods for controlled entanglement. Herein, we report the stereoselective synthesis of a 24-metal-center topologically chiral [6]catenane featuring 18 crossings ( link), representing one of the most intricate MIMs constructed to date.

pH-Dependent reversible crystal transformation of 1-carboxymethyl-1-methyl-pyrrolidinium bromides and their spectroscopic fingerprint.

In this work, two 1-carboxymethyl-1-methyl-pyrrolidinium bromides (N-methylpyrrolidine betaine hydrobromides) with the stoichiometry of betaine:hydrobromic acid as 1:1 and 2:1, denoted as CMPRHBr-I and CMPRHBr-II, respectively, were prepared and crystallographically determined. The large difference in these two structures is the type of hydrogen bonds, resulting in the different thermal stability. A strong OH⋯Br hydrogen bond was observed in CMPRHBr-I, whereas O⋯H⋯O hydrogen bond in CMPRHBr-II.

A four-unit [c2]daisy chain connected by hydrogen bonds.

A mono-adenine-functionalized pillar[5]arene and a guest including uracil were prepared. They formed a novel four-unit [c2]daisy chain both in the solid state and in a chloroform solution. As far as we know, this [c2]daisy chain is the first one without a covalently bound linear thread.

From a binary salt to salt co-crystals of antibacterial agent lomefloxacin with improved solubility and bioavailability.

The cocrystallization of lomefloxacin (Lf) with barbituric acid (HBA) and/or isophthalic acid (H2ip) leads to novel binary and ternary salts via hydrogen-bonding recognition. X-ray single-crystal diffraction analyses show that zwitterionic lomefloxacin can adjust itself to fulfill a different supramolecular array in either binary salts or ternary salt co-crystals, formulated as [HLf]·[Hip]·H2O (1), [HLf]·[BA]·[HBA]·H2O (2) and [HLf]·[BA]·[H2ip]·CH3OH·H2O (3). These pharmaceutical agents present uniform charge-assisted hydrogen-bonding networks between HLf cations and acidic coformers with the lattice capturing water molecules.

[Ab initio calculations of vibrational frequencies and structures of ion pairs of perchlorate].

Ion association of solutions of lithium perchlorate in N,N-dimethylformamide, acetonitrile, tetrahydrofuran, acetone, methyl acetate and other organic solvents have been investigated by infrared and Raman spectroscopy, respectively. The spectroscopically free ion, contact ion pair and dimer are fingerprint by the curve fitting of upsilon1 band of. The most stable geometries of contact ion pairs and dimmer, and the vibrational frequencies were optimized and calculated using the ab initio methods.

[Theoretical study on structure and vibrational spectra of M+ AsF6- (M=Li, Na, K, Rb and Cs) contact ion pairs].

The present paper reports the possible geometries and vibrational spectra of AsF6- anion and M+ AsF6- (M+ = Li+, Na+, K+, Rb+ and Cs+) contact ion pairs. It was shown that the tridentate C3v structure of M+ AsF- was preferred over the monodentate and bidentate geometry. In the tridentate structure, the symmetry of AsF6- in the coordination is lowered because of the presence of M+, and its structural parameters and vibrational modes largely differ from its original octahedral structure.

(2,9-Dimethyl-1,10-phenanthroline-κN,N')bis-(2-hydroxy-benzoato)-κO;κO,O'-cobalt(II).

In the title compound, [Co(C(7)H(5)O(3))(2)(C(14)H(12)N(2))], the Co(II) ion is five-coordinated by two N atoms from one 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and three O atoms from two 2-hydroxy-benzoate anions in a distorted trigonal bipyramidal geometry. The carboxyl-ate group of one of the two 2-hydroxy-benzoate anions is monodentate with a normal Co-O distance [1.9804 (18) Å], while the other is bidentate with two longer Co-O bonds [2.

Bis(benzoato-κO,O')(2,9-dimethyl-1,10-phenanthroline-κN,N')cobalt(II).

In the title compound, [Co(C(7)H(5)O(2))(2)(C(14)H(12)N(2))], the Co(II) ion is located on a twofold rotation axis and is chelated by a 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and two benzoate anions in a distorted octa-hedral geometry. The crystal packing is stabilized by π-π inter-actions between parallel dmphen ligands of neighbouring mol-ecules, with a face-to-face distance of 3.411 (2) Å.

Factors affecting ionic liquids based removal of anionic dyes from water.

Liquid--liquid extraction with imidazolium based ionic liquids--[C4mim][PF6], [C6miml][PF6], [C6mim[BF4], and [C8mim][PF6--is proposed for removal of anionic dyes including methyl orange, eosin yellow, and orange G from aqueous solutions. The effects of extraction time, pH of aqueous phase, structure of the ionic liquids, temperature, and KCl concentration on the extraction efficiencies have been studied. Extraction efficiencies of dyes were strongly affected by the pH of the aqueous phase.

Bis(μ-3-hydroxy-benzoato-κO,O':O)bis-[aqua-(3-hydroxy-benzoato-κO,O')(1,10-phenanthroline-κN,N')lead(II)] monohydrate.

In the centrosymmetric binuclear title complex, [Pb(2)(C(7)H(5)O(3))(4)(C(12)H(8)N(2))(2)(H(2)O)(2)]·H(2)O, each Pb atom is eight-coordinated in a PbO(6)N(2) environment by two N atoms from the 1,10-phenanthroline (phen) ligand, five carboxylate O atoms from four 3-hydroxy-benzoate anions and one O atom from the coordinated water mol-ecule in a distorted bicapped trigonal-prismatic geometry. The benzoate groups coordinate each Pb(II) atom in two different ways. Two benzoate ions behave as bidentate ligands to the Pb atom, and another benzoate ion bridges the Pb atoms, forming a binuclear structure.

Erratum: catena-Poly[[(2,9-dimethyl-1,10-phenanthroline-κN,N')lead(II)]-di-μ-2-hydroxy-benzoato-κO,O:O;κO:O,O]. Corrigendum.

A reference in the paper by Xuan & Zhao [Acta Cryst. (2007), E63, m2678] is replaced.[This corrects the article DOI: 10.

[Ion solvation and ion association in high-concentration of NaBF4/DMF solutions].

Ion solvation and ion association in solutions of NaBF4/DMF were studied by infrared and Raman spectroscopy and ab initio quantum chemistry. It was found that the sodium cation interacts on oxygen atom of C=O group in DMF molecules. The solvation number of Na+, four, was obtained according to the change analysis of CH3 rocking band.