New ligand systems for ions and molecules - and electronic effects upon complexation

Chromophore-ionophores are described, which upon complexation give ion-selective colour changes. Thus, dyestuffs can be influenced either in a hypsochromic or in a bathochromic way. Bond formation and bond cleavage reactions as well as organic catalysts are likewise electronically influenced by ion-selective complexation, so that an accurate steering of reactivities by ions is possible. Neutral guest molecules form definite complexes with crown ethers and their analogues. Crystalline phenyl hydrazine complexes can serve as stable reagents for the derivatisation of carbonyl compounds to the corresponding hydrazones in lipophilic solvents. Volatile toxic substances, which are used as reagents for alkylation and acylation reactions, can be converted into crystalline stoichiometric neutral complexes. It seems possible to develop receptor cavities for urea and other molecules of physiological interest.