RESUMO
Inorganic anions were used as templates in the reaction between a diamine and an activated diacid to form macrocyclic amides. The reaction conditions were found to perform the macrocyclization sufficiently slow to observe a template effect. A number of analytical methods were used to clarify the reaction mechanisms and to show that the structure of the intermediate plays a decisive role in determining the product distribution. For the macrocyclization under kinetic control, it was shown that the amount of a template, the conformational rigidity of building blocks, and the anion affinities of reaction components and intermediates are important parameters that one should take into consideration to achieve high yields.
RESUMO
The design and synthesis of a neutral macrocyclic host that is capable of perrhenate and pertechnetate recognition is described. The anion affinities and underlying coordination modes were estimated by several experimental and theoretical methods including a new technique--reverse (99)Tc NMR titration.
Assuntos
Compostos Macrocíclicos/síntese química , Rênio/química , Pertecnetato Tc 99m de Sódio/química , Ânions/química , Cristalografia por Raios X , Compostos Macrocíclicos/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , EstereoisomerismoRESUMO
This tutorial review covers the chemistry of artificial receptors designed to recognize the pertechnetate and perrhenate anions. It focuses on the molecular features that give rise to effective and selective complexation. Specific receptor classes are discussed in the context of available solution-phase and solid-state data with differences between pertechnetate and perrhenate binding behavior being highlighted where appropriate.
