Solution thermodynamics of geometrical isomers of pyridino calix(4)arenes and their interaction with the silver cation. The X-ray structure of a 1:1 complex of silver perchlorate and acetonitrile with 5,11,17,23-tetra-tert-butyl-[25,26,27,28-tetrakis(2- pyridylmethyl)oxy]calix(4)arene

Abstract

The solubility and derived standard Gibbs energies of solution of three geometrical isomers of pyridinocalix(4)arenes M5,11,17,23-tert-butyl-[25,26,27,28-tetrakis-(n-pyridylmethyl) oxy]-p-tert-butylcalix(4) arene, with n \ 2, 3, 4N in a variety of solvents at 298.15 K are reported. Solvation e †ects are assessed from the standard transfer Gibbs energies of these ligands, using acetonitrile as the reference solvent. For the 2-pyridyl derivative in alcohols as the aliphatic chain length of the alcohol increases, the extent of solventÈligand interaction increases, whereas for the 3-and the 4-pyridyl derivatives the opposite is observed. The protonation constants for the 4-pyridyl derivative in methanol at 298.15 K are reported. The results, compared with corresponding values for the 3-pyridyl derivative show that the basic character of these ligands follows the sequence ; 4-pyridyl [ 3-pyridyl [ 2-pyridyl calix(4)arene. Thermodynamic parameters for the complexation of these macrocycles (2 and 4-pyridyl derivatives) and the silver cation in acetonitrile show that, as the distance between the phenolic oxygens and the pyridyl nitrogens increases, the strength of complexation decreases. Thermodynamic data for the complexation of silver and the 2-pyridylcalix(4)arene derivative are compared with corresponding values for sodium and this ligand in the same solvent. The results suggest that the 2-pyridyl derivative provides phenolic oxygens and pyridyl nitrogens as the active sites for complexation with silver. This is corroborated by 1H NMR measurements of this ligand and silver in at 298 K. CD 3 CN The crystal structure of a 1 : 1 monoacetonitrile and silver complex of the 2-pyridyl derivative with perchlorate as the counter-ion has been determined from XRD data. The substance crystallises in the tetragonal space group P4/n with a \ 15.580(2) c \ 13.082(2) and z \ 2. The macrocycle is sited on a Ó, Ó, fourfold symmetry axis and consists of two conical parts, one hydrophobic, Ðlled with an acetonitrile molecule, the other hydrophilic, encapsulating the Ag`ion through the ethereal oxygen [d(AgÉ É ÉO) \ 2.923(3) and Ó] pyridine nitrogen atoms [d(AgÉ É ÉN) \ 2.483(5)The coordination around the Ag`ion has the form of a Ó]. distorted Archimedean square antiprism. The ability of the macrocycle to complex the silver cation in its hydrophilic cavity is demonstrated.

Design and synthesis of a cyclitol-derived scaffold with axial pyridyl appendages and its encapsulation of the silver(I) cation

“…The electrospray mass spectrum (from the very solution contained in the NMR tube) revealed a 1:1 complex, with the expected 107 Ag/ 109 Ag isotopic ratio. The stability constant of the complex could be determined by spectrophotometric titration, which was carried out in 1:1 aqueous methanol (the complex is not water soluble) and its value (log K 1 ·Ag = 3.8 ± 0.2) is in agreement with that of a previously described Ag(I) complex in a N 3 O 3 environment [13]. …”

“…3 ). Bond distances and angles (see Supporting Information File 1 ) are in accord with those of known silver complexes which are hexa-coordinated with pyridyl groups and oxygen atoms [ 13 – 14 ].…”

Extraction of silver (I) by calixarene amine derivatives: The medium effect on the stoichiometry of the phase transfer extraction process

“…Since K 0 s ) K 00 s it is reasonable to assume that the individual processes contributing to the overall extraction of this cation from water by the calix(4)arene amine derivative in the organic phase are those involved in eqn. (13). Given that for a given electrolyte in a given solvent system, K p values are identical, the variations observed in the extraction constants are attributed to the difference in the strength of ionligand interaction and ion-pair formation between the complex cation and the anion in the organic phase.…”

“…[5][6][7][8][9] Calix(4)arene derivatives containing aliphatic and alicyclic amines as pendent arms at the narrow rim have been shown to be suitable complexing agents for the silver cation. [10][11][12][13] This property led to an investigation of their extraction abilities for silver in the water-nitrobenzene (H 2 O-PhNO 2 ) solvent system. 14 Thus, distribution experiments in the absence and in the presence of calix(4)arene amine derivatives in this solvent system were carried out.…”

Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir–Blodgett films

“…Several approaches have been reported; some recent examples include Ag + complexes, [29][30][31][32] silver clusters, 33 AgNPs with β-cyclodextrin capping, 34 electrochemically produced silver ions 35 and genetically engineered Ag + binding phage fibers. 36 In supramolecular chemistry, silver complexes with macrocyclic hosts, such as crown ethers, 37 calixarenes and resorcinarenes, [38][39][40][41] and calixcrowns [42][43][44][45] are known. As a soft acid, silver prefers coordination to soft (N, S) donors, 37,40,43,44 but coordination to hard donors (O) and π-basic binding sites has also been observed.…”