Insights into Complex Compounds of Ampicillin: Potentiometric and Spectroscopic Studies.

Metal ions, including Mg(II), Ca(II), Sr(II), Co(II), Ni(II), Cu(II), Nd(III), Eu(III), and Tb(III), were investigated in binary systems alongside ampicillin at molar ratios of 1:1 and 1:2. These investigations were carried out in aqueous solutions, and the formation of complexes was verified through meticulous computational analysis. Detailed stability constants for the formed complexes and equilibrium constants for the involved reactions were meticulously determined.

Spectroscopic Studies of Lanthanide(III) Complexes with L-Malic Acid in Binary Systems.

Binary systems of lanthanide ions (La, Nd, Gd, Ho, Tb, and Lu) with L-malic acid in molar ratios of 1:1 and 1:2 were studied. This study was carried out in aqueous solutions, and the composition of the formed complexes was confirmed using computer data analysis. The overall stability constants of the complexes and the equilibrium constants of the reaction were determined.

Thermodynamic Studies of Complexes in Cu(II)/Uridine-5'-Diphosphoglucuronic Acid System.

A binary system of uridine-5'-diphosphoglucuronic acid with copper (II) ions was studied. Potentiometric studies in aqueous solutions using computer data analysis were carried out. The pH of dominance, the overall stability constants (log), and the equilibrium constants of the formation reaction (log) were determined for each complex compound formed in the studied system.

Biocoordination reactions in copper(II) ions and phosphocholine systems including pyrimidine nucleosides and nucleotides.

The complexation reactions of phosphocholine and pyrimidine nucleosides as well as nucleotides with copper(II) ions were studied in the water system. Using potentiometric methods and computer calculations, the stability constants of the species were determined. Using spectroscopic methods such as UV-vis, EPR, C NMR, P NMR, FT-IR and CD, the coordination mode was established for complexes created in pH range 2.

Recent Advances in the Synthesis and Applications of Nitrogen-Containing Macrocycles.

Macrocyclic nitrogen-containing compounds are versatile molecules. Supramolecular, noncovalent interactions of these macrocycles with guest molecules enables them to act as catalysts, fluorescent sensors, chiral or nonchiral selectors, or receptors of small molecules. In the solid state, they often display a propensity to form inclusion compounds.

Controlled, Sunlight-Driven Reversible Cycloaddition of Multiple Singlet Oxygen Molecules to Anthracene-Containing Trianglimine Macrocycles.

Controlled release of singlet oxygen is of interest not only to chemists, but also to biologists and medics involved in cancer therapy. Two chiral polyaza macrocyclic compounds and their corresponding endoperoxides have been synthesized. These peroxides exhibit high temperature stability, up to 80 °C.

Thermodynamic and Spectroscopic Studies of the Complexes Formed in Tartaric Acid and Lanthanide(III) Ions Binary Systems.

Binary complexes of tartaric acid with lanthanide(III) ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data for detection of the complexes set, determination of the stability constants of these compounds. The mode of the coordination of complexes found was determined using spectroscopy, which shows: Infrared, circular dichroism, ultraviolet, visible as well as luminescence spectroscopy.

Solvent-assisted synthesis of a shape-persistent chiral polyaza gigantocycle characterized by a very large internal cavity and extraordinarily high amplitude of the ECD exciton couplet.

A giant, chiral square-shaped octaimine macrocycle has been obtained in a controlled manner from readily available and inexpensive substrates: 9,10-diphenylanthracene-based dialdehyde and trans-1,2-diaminocyclohexane. Reduction of the polyimine led to a chiral octaamine characterized by a very large internal hydrophobic cavity.

One-Step Construction of the Shape Persistent, Chiral But Symmetrical Polyimine Macrocycles.

A unique combination of structural flexibility, shape persistency and functionality, makes macrocycles and molecular cages as essential molecular entities that have displayed applications that go beyond chemistry. Among macrocycles, the selectively obtained symmetrical (poly)cyclic polyimines have shown great utility in the design of molecules varied in shape and properties. The reversible and thermodynamically controlled cycloimination reaction is governed by configurational and conformational constraints imposed on the intermediate products, ensures a sufficiently high level of preorganization.

Benzhydryl Ethers of Tartaric Acid Derivatives: Stereochemical Response of a Dynamically Chiral Propeller.

The benzhydryl (diphenylmethyl) group is a molecular propeller that can act as a chirality reporter if it is introduced nearby a stereogenic center by making an ether bond. The hydrophobic character of the benzhydryl group allows transformation of insoluble natural tartaric acid derivatives into soluble entities in a nonpolar environment. Electronic circular dichroism spectra, recorded within the short-wavelength region of the phenyl B transitions (190-200 nm) shows strong bisignate Cotton effects.

Intramolecular interactions of trityl groups.

Trityl group, Tr, is a molecular dynamic rotor of which the conformation and helicity depend on other groups in the close vicinity. Interactions with another covalently linked Tr group and with other substituents are analyzed in terms of transfer of chirality to the trityl group. Two trityl groups in a molecule can mutually interact at a distance of two, three, or five bonds.

Multinuclear magnetic resonance studies of fluoronitroanilines.

Ten fluoronitroanilines have been synthesized and the (1)H, (13)C, (15)N and, (19)F NMR spectra of these compounds have been recorded and fully assigned. Density functional theory(DFT) calculations have been performed for all compounds studied. Experimental and theoretical results are compared and the structure and atom character influence on the accuracy of the calculation discussed.

Discrimination of enantiomers of alpha-amino acids by chiral derivatizing reagents from trans-1,2-diaminocyclohexane.

New chiral derivatizing reagents (CDAs) derived from trans-1,2-diaminocyclohexane, having an electron-deficient aromatic substituent (either an aromatic imide or 3,5-dinitrobenzamide) and rigid structure (either an amide or a urea linker), are reported. Significant shift differences of diastereotopic protons in the 1H NMR signals are observed for enantiomers of suitably protected alpha-amino acids, linked to CDA by a covalent bond. A simple, general model rationalizing the observed enantiomer discrimination and based on semiempirical conformational search is presented.

Trianglamines--readily prepared, conformationally flexible inclusion-forming chiral hexamines.

Trianglamines, macrocyclic heteraphanes, were readily synthesised through a [3+3] cyclocondensation of (R,R)-1,2-diaminocyclohexane with terephthalaldehyde, followed by NaBH4 reduction and N-alkylation. The macrocyclic ring shows a remarkable ability to change its conformation, as a consequence of rotation about the C-N bonds or nitrogen inversion due to protonation or N-alkylation, as revealed by circular dichroism spectra, computational modelling and X-ray diffraction analysis. The flexible natures of the trianglamine macrocycles allow ready accommodation of a variety of guest molecules to form crystalline inclusion complexes of highly diversified interpenetrating structures.

Conformational response of tartaric acid to derivatization: role of 1,3-dipole-dipole interactions.

The four-carbon chain in (R,R)-tartaric acid derivatives is predominantly antiperiplanar (trans) in the acid, its salts, esters, and NH-amides, while (-)-synclinal (gauche) conformer is the most abundant in N,N'-tetraalkyltartramides. Trialkylsilylation or tert-butylation of the hydroxy groups at C2 and C3 does not appear to affect the conformational preference of NH-tartramides, but it does change the conformational equilibrium in the case of tartrates (toward (-)-gauche) and N,N'-tetraalkyltartramides (toward trans), as judged from the NMR data. X-ray diffraction data point to the stabilizing role of antiparallel dipole-dipole interactions due to the 1,3-CO/CH bonds.

The first nonempirical circular dichroism determination of the absolute configuration of N-phthalimidosulfoximines based on exciton coupling mechanism and a correlation with the absolute configuration of chiral sulfoxides.

A simple nonempirical method for the assignment of absolute configuration of N-phthalimidosulfoximines and related S-chiral sulfoxides, based on exciton-coupled circular dichroism, is presented.

Folding of aromatic oligoimides of trans-1,2-diaminocyclohexane.

Chiral oligomeric diimides prepared from pyromellitic dianhydride, (R,R)-1,2-diaminocyclohexane and phthalic anhydride fold into M or P helical conformers; trimer 1 folds into the P conformer in the crystal but the M conformer dominates in solution; longer chain oligomers 2 and 3 form preferentially P conformers in solution, as a result of intermolecular interactions.