Cooperative effects in the binding of two or more substrates to different binding sites of a receptor that are a result of a conformational change caused by the binding of the first substrate--also referred to as the effector--are called allosteric effects. In biological systems, allosteric regulation is a widely used mechanism to control the function of proteins and enzymes in cellular metabolism. Inspired by this a lot of efforts have been made in supramolecular chemistry to implement this concept into artificial systems to control functions as molecular recognition, signal amplification, or even reactivity and catalysis. This review gives an up-to-date overview over the different approaches that have been reported ever since the first examples from the late 1970s/early 1980s. It covers both homo- and heterotropic examples and is divided according to the nature of the effector--cationic, anionic, or neutral--effectors and systems that use combinations of those.

Objective To assess the impact of isolated lesions of the fetal right heart on ductus venosus (DV) blood flow profiles. Methods

SummaryHerein, we present three new 2,2’-bipyridines that carry two β-cyclodextrin moieties in different substitution patterns. When coordinated by zinc(II) or copper(I) ions (or their complexes), these compounds undergo conformational changes and switch between “open” and “closed” forms and thereby bringing together or separating the cyclodextrin moieties from each other.

A new β-cyclodextrin-based receptor that showed allosteric binding behavior towards capsaicin in aqueous solution was prepared. By NMR titration and nonlinear regression, we obtained binding constants, which increased more than fivefold when an effector (Zn(2+)) was bound to a central 2,2'-bipyridine that acts as the allosteric center.

Three new diisothiocyanato-functionalized 2,2¢-bipyridines have been synthesized in four consecutive steps. Starting from 4-amino-2-chloro-and 2-amino-6-bromopyridine, respectively, we first prepared the corresponding diamino-2,2¢-bipyridines via homo-or Negishi cross-coupling reactions which were subsequently reacted with thiophosgene.