Synthesis, x-ray structure and anion binding properties of a cryptand-like hybrid calixpyrrole

The novel cryptand in/out-3, containing two tripyrrolemethane units briged by three 1,3- diisopropylidenbenzene arms was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid state X-ray structure of the free cryptand 3 was also determined.

Ditopic molecular architectures for the recognition of anionic species

Dissertation presented to obtain the Ph.D degree in Chemistry

Agentes complexantes: podante, coronante e criptante classificação e nomenclatura

The scientific and practical interest in crown ethers as complexing agents for actions as well as for anions and neutral low molecular species is undeniable. New molecules with crown ether properties are constantly synthesized and new application discovered. This paper presents classification and nomenclature of the classical oligoethers (crown ethers): monocyclic coronands; oligocyclic spherical cryptands; and acyclic podands.

Pyrrole-based metallo-macrocycles and cryptands

The synthesis of dithiocarbamate ligands based on a pyrrole framework is reported. These ligands self-assemble with zinc(II), nickel(II) and copper(II) to afford neutral, dinuclear metallomacrocycles and trinuclear metallocryptands. The assembled metallo compounds have been characterised by a range of techniques, including H-1 NMR, UV-vis spectroscopy, elemental analysis, mass spectrometry and X-ray crystallography. Some preliminary anion binding studies have also been conducted, using electronic spectroscopy and electrochemistry. The nickel macrocycles showed some affinity for acetate, whereas the copper cryptand showed affinity for benzoate anions. The copper cryptand also exhibited a significant electrochemical response to a range of anions.

Halo-derivatised calix[4]tubes

Halo functionalisation of calix[4] tubes has been investigated through both derivatisation of individual calix[4]arenes and calix[4] tubes, using classical synthetic methods, to allow preparation of a series of novel derivatives. The solution and solid state properties are in accordance with the constituent calix[4] arenes adopting flattened cone arrangements which on complexation with potassium simplify to a regular cone. Electrospray and H-1 NMR studies, combined with molecular modelling have been used to ascertain the metal binding of this new series of cryptand like ionophores, demonstrating their retained selectivity for binding potassium over other Group 1 metals and the dependence on counter anion in the weak binding of silver.

Thallium pi-cation complexation by calix[4]tubes: Tl-205 NMR and X-ray evidence

Thallium cation complexation by calix[4]tubes has been investigated by a combination of (TI)-T-205, H-1 NMR and ES MS demonstrating the solution formation of a dithallium complex in which the cations are held in the calix[4]arene cavities. In addition, the structure of the complex has been determined in the solid state revealing the cations to be held exclusively by pi-cation interactions. Furthermore, this crystal structure has been used as the basis for molecular dynamics simulations to confirm that binding of the smaller K+ cation in the calix[4]tube cryptand like array occurs via the axial route featuring a g-cation intermediate.

Ionic Recognition by 7-Nitro-1,3,5-triaza Adamantane: First Thermodynamic Study

A thermodynamic study involving 7-nitro-1,3,5-triaza adamantane, 1, and its interaction with metal cations in nonaqueous media is first reported. Solubility data of 1 in various solvents were used to derive the standard Gibbs energies of solution, Delta G(s)degrees in these solvents. The effect of solvation in the different media was assessed from the Gibbs energy of transfer taking acetonitrile as a reference solvent. (1)H NMR studies of the interaction of 1 and metal cations were carried out in CD(3)CN and CD(3)OD and the data are reported. Conductance measurements revealed that this ligand forms lead(II) or zinc complexes of 1: 1 stoichiometry in acetonitrile. It also revealed a stoichiometry of two molecules of 1 per mercury(II) and two cadmiu (II) ions per molecule of 1. The addition of silver salt to 1 led to the precipitation of the silver-1 complex which was isolated and characterized by X-ray crystallography. At variance with conductance measurements in solution, in the solid state the X-ray structure show`s a 1:1 stoichiometry in the Hg(II) complex. The themiodynamics of complexation of 1 and these cations provide a quantitative assessment of the selective behavior of this ligand for ions of environmental relevance.