Insertion reactions of macrocyclic rhodium carbenoids: a novel method for the synthesis of cryptands

Reaction of macrocyclic diazocarbonyl compounds and alcohols or diols in the presence of rhodium(II) acetate catalyst led to functionalized macrocyclic di- or tetralactones via O-H insertion. Interestingly, the double O-H insertion reaction with dihydroxy compounds gave cryptands of various ring sizes.     

New small-cavity cryptand chromoionophores for complexation of lithium and sodium ions

Two new chromoionophores based on small-cavity cryptands with inward-facing phenolic groups have been synthesized. Both compounds incorporate a diaza-12-crown-4 moiety and bear ap-nitrophenylazo chromogenic group attached to the cryptand phenol framework,para to the phenolic group. Chromogenic crytand3 exhibits selectivity for Li⁺ ions in the extraction mode but shows very little cation response in homogeneous aqueous media. A larger analog, chromogenic cryptand4, acts as a sodium scavenger and cannot be obtained in a sodium-free form.     

Electrochemical study of oxaferrocene cryptands and their complexation with barium and sodium ions

The electrochemical behaviour and cation recognition properties of two oxaferrocene cryptand ligands, 1,1′-[(1,4,10-trioxa-7,13-diazacyclopentadecane-7,13-diyl)diethoxy]-3,3′,4,4′-tetraphenylferrocene and 1,1′-[(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)diethoxy]-3,3′,4,4′-tetraphenylferrocene, have been characterized in acetonitrile in the presence of Ba²⁺ and Na⁺ by cyclic voltammetry, square wave voltammetry and a rotating disc electrode. The changes in the redox signals for the cryptates at varying concentrations of the target cations are used as a direct measure of the electronic coupling between the two units, leading to the conclusion that the cryptate formation process proceeds in multiple stages and the ligand offers several binding sites in the complex.     

Modulation of SHG responses via supramolecular association/dissociation between two complementary cryptands

Two sets of complementary cryptands are investigated for supramolecular nitro-amino H-bonding interactions in solutions. The D-π-A cryptand and the unsubstituted cryptand forms 1:1 H-bonded structure. Its second harmonic generation capabilities in solution are explored by HRS titration experiments. Supramolecular assembly leads to spontaneous increase of the SHG intensity, which undergoes steady decrease on addition of MeOH due to the breakdown of the H-bonded structure. Thus, NLO responses can be reversibly modulated by applying such supramolecular principles.     

A Potassium Complex of a Fluorine-Containing Macrocyclic Cage Compound: Interactions between Fluorine Atoms and Metal Ions

A new donor , the C−F unit, can be added to the field of host–guest chemistry. The interaction between fluorine atoms and a potassium ion was proven with the fluorine-containing cage compound 1 as a host. The six fluorine atoms of K⁺⊂ 1 are coordinated to K⁺ in a distorted octahedral fashion.     

Synthesis and complexing abilities of novel benzocryptands

Two novel benzocryptands based on hydroquinone and 2-methoxyhydroquinone and a cylindrical tricyclic cryptand based on the former have been synthesized. Complexing abilities of the benzocryptands for Na⁺, K⁺ and Rb⁺ and of the tricyclic cryptand for diammonium cations are determined and compared with those reported for structurally-related compounds.     

Toward dynamic combinatorial libraries of cryptands

The first examples of dynamic combinatorial libraries of cryptands, created using the chemistry of imines is presented. Experiments, in which two trialdehydes compete for one triamine in a small library, show the full reversibility of cryptand formation, since the library composition is the same irrespective of the sequence of introducing the building blocks to the mixture.     

Correlation of the Structure and Properties of Alkalides and Electrides That Contain Cryptands or Crown Ethers

Abstract

The structures of several salts that contain alkali metal anions (alkalides) and two that contain trapped electrons (electrides) are correlated with their optical and NMR spectra, and magnetic susceptibilities. The nature of the channels and trapping sites in the two electrides are described.