No abstract

Several macrocyclic bis(amide) derivatives of DTPA and EDTA were prepared. Protonation constants as well as Gd3+ and Zn2+ complex stability constants of these ligands were determined by potentiometric titrations. The stability constants of the Gd3+ complexes increase with increasing ring size of the DTPA bis(amide) macrocycle series, reflecting the enhanced participation of the amide carbonyl oxygens in metal ion coordination. On the other hand, the stability constants of the Zn2+ complexes do not exhibit any particular trend throughout the series. The logarithmic selectivity constant of the 15-membered EDTA-DAM ligand for Gd3+ over Zn2+ (the difference between logarithmic stability constants of Gd(EDTA-DAM) and Zn(EDTA-DAM)) is 6.12. This indicates that the ligand EDTA-DAM exerts by far the highest selectivity for Gd3+ over Zn2+ among known polyamino polycarboxylates, presumably through a more favorable structural discrimination by this ligand. In contrast, the structural isomer DTPA-EAM shows a less favorable selectivity for Gd3+ over Zn2+.

No abstract

Substitution of fluorine for the aldehydic hydrogen provides behaviorally active, chemically reactive pheromone mimics. In male moths of the tobacco budworm Heliothis virescens, zg-14:Acf and Zll-16:Acf cause hyperactivity and irreversible extension of the genitalia in over 80 % of treated moths. In addition, a combination of the two components leads to 10-50 % of the pairs involving one treated partner becoming locked in copula.