Preparation of Polymer-Supported Polyazamacrocycles. The Role of the Polymeric Matrix in the Preparation of Polymer-Supported Polyazamacrocycles

Different approaches have been studied for the preparation of resins containing different polyazamacrocycles. Preparation of monolithic resins by polymerization of vinylic derivatives of the corresponding macrocycles is shown to be a more versatile strategy for this purpose. The use of energy-dispersive analysis by X-ray has revealed to be a very useful tool for the rapid evaluation of the interaction of those materials with both anions and cations and has allowed the corresponding selectivity trends to be obtained in a fast and simple way. Important effects of the polymeric matrix are observed in some cases.

Arynic species; effect of substituents on the reactivity of monosubstituted dehydrobenzenes

Abstract Evidence is presented demonstrating the existence of free dehydrobenzenes in the thermal decomposition of diaryliodonium-2-carboxylates, and that o-benzyne itself and its 4-methyl-, 4-chloro-,4-bromo- and 4-nitro-derivatives are generated from insoluble polymer-bound precursors and trapped by a second solid phase in Diels-Alder reactions. Lifetimes for these elusive species are determined.

Enhanced transport through binding cooperativity in a circulating system

Abstract Allosteric cooperativity in a multiphase circulating system is shown to enhance ion transport when long contact times are involved.

ChemInform Abstract: Evidence for the Formation of 1,3- and 1,4-Dehydrobenzenes in the Thermal Decomposition of Diaryliodonium-carboxylates.

Abstract Abstract: Generation of m- and p-benzynes in decomposition of diaryliodonium- 3- and 4-carboxylates is demonstrated by three-phase method.

Arynic species II

Abstract o-Benzyne and its 4-methyl, 4-chloro and 4-bromo-derivatives were generated in the thermal decomposition of two new kinds of polymer-bound precursors: 1(2-carboxyaryl)triazenes and 2-carboxyaryl-sulphonates. New kinds of trapping polymers for these elusive species are also presented.

Coamplexation of mercury(II) compounds by crown ethers in organic media

Complexes between crown ethers having ring sizes of 15–24 atoms and 5 to 8 oxygens with HgX2 species (X = Cl, I, CN, SCN) have been prepared and studied. Interactions of the substituents X bound to mercury with groups or fragments in the crown compound are essential in determining the characteristics and stability of the complexes formed. Complexes with crowns of 18C6 ring sizes are the most favourable except for HgX2 compounds for which the size of X is larger than the macrocycle ring, as is the case for X = CF3.

Generation of monosubstituted o-benzynes from polymeric reagents via heterolytic fragmentations

Abstract Generation of four 4-substituted o-benzynes by heterolytic — fragmentation reactions is demonstrated.

Chemosensors displaying pH controlled multistage fluorescence emission

A large number of systems displaying pH controlled multistages of fluorescence emission intensity, have not been recognized from this point of view. In this work we present two paradigmatic cases: (i) polyamine receptors linked to a fluorophore unit, in which the signal is modulated by an intra-molecular pH dependent electron transfer process, (ii) phenols presenting adiabatic excited state proton transfer. In the first example the chemosensors are constituted by a receptor unit containing a polyaza moiety suitable for binding protons (but also metal ions or anions). The receptor is linked to a benzene or naphthalene unit that acts as a fluorophore. The fluorescence signal is dependent on t…

The fischer indole synthesis of 8-methyl-5-substituted-1-oxo-β-carbolines: A remarkable high yield of a [1,2]-methyl migration.

Abstract A very unusual high yield of rearranged products (via methyl migration) has been obtained in the Fischer indole cyclization of the 3-(2,5-dimethyl phenylhydrazone) of 2,3-piperidine dione (6b). When a less activated aromatic ring is present in the phenylhydrazone 6, such a behaviour is not observed and cyclization occurs essentially without rearrangement.

New Insight to the Chemistry of Polyaza[n]paracyclophanes. A 15N NMR Study

Small Azaparacyclophanes as Potential Selective Scavengers of Mercury. Crystal Structure of the Complex Hg2(L1)Cl4 (L1 = 16,17,19,20-Tetramethyl-2,6,9,13-tetraaza[14]paracyclophane)

Evidence for the formation of 1,3- and 1,4-dehydrobenzenes in the thermal decomposition of diaryliodonium-carboxylates

Abstract Abstract: Generation of m- and p-benzynes in decomposition of diaryliodonium- 3- and 4-carboxylates is demonstrated by three-phase method.