Search

The sensing properties towards aliphatic α,ω-dicarboxylates of five cyclohexane-based ligands are described. The studied ligands have been designed following the binding site-signalling unit approach and they all possess thiourea groups as recognition moieties. Ligands 1 and 3 containing naphthalene units can be used as fluorescent sensors as they form intra- or intermolecular excimers in the presence of appropriate dicarboxylates. Selective sensing of succinate and malonate versus their longer or shorter homologues has been observed.

Five heteroditopic ligands have been prepared to be used in solid–liquid extraction of ω-amino acids into DMSO solutions. The prepared ligands contain crown ethers as cation binding sites and thiourea or amide groups for anion recognition. The aliphatic zone of the 1H NMR spectra suggests that two different species related to the amino acid are present in solution. One of these species is the complexed zwitterionic form and the other seems to be free non-zwitterionic amino acid. The presence of these two species allows extraction efficiencies higher than 100%.

Four new homoditopic biphenyl thiourea derivatives have been prepared to be used in carboxylate sensing. Experiments carried out with these ligands have demonstrated that the conformation of the free ligand has a strong influence on both complex stoichiometry and geometry. High equilibrium constants were obtained in DMSO.

Six new biphenyl thiourea derivatives have been prepared to be used in carboxylate sensing. Experiments carried out with these ligands have demonstrated that the type of interaction with TBA carboxylates is strongly dependent on the substituents in the thiourea moiety. These interactions go from the formation of 1:1 hydrogen-bonded complexes to acid–base reactions. In addition, different geometries have been observed for the complexes being dependent on the conformations of the free ligands in solution.

The photodeacetalization of 4-(p-isopropylphenyl)-2-nonyl-1,3-dioxolane 1 using 2,4,6-triphenylpyrylium tetrafluoroborate (TPT) as sensitizer has been studied to explore the possibility of achieving a slow sunlight-controlled release of polymer-bound carbonyl functionalized semiochemicals. This reaction has been found to produce mainly n-decanal and p-isopropylbenzaldehyde, together with lower amounts of the corresponding acids. The degree of conversion and the product distribution depended on the presence of water or oxygen and the amount of photosensitizer. The results are justified through generation of the radical cation 1+·, followed by ring opening and trapping of the radical/cationic sites by oxygen or water. The delocalized 1,3-radical cations III and the ozonides IV appear to be involved as key intermediates. Formation of n-nonanal as a minor product is explained through cleavage of the C2-nonyl bond of 1+·.

Substituted 2-cyclohexenones 4 to 7 and hexaxydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.