Biindole-bridged porphyrin dimer as allosteric molecular tweezers

A multiple-guest-binding molecular tweezers that exhibits notably strong positive allosteric guest binding phenomena has been reported. Tweezers-type zinc porphyrin dimer and biindole-conjugated monomeric porphyrin were synthesized and characterized H NMR C NMR, and MALDI-TOF-MS analyses. Molecular tweezers are a class of synthetic receptors with open cavities, capable of binding guests using non-covalent interactions, such as hydrogen bonding, metal coordination, and van der Waals forces. Allosteric guest binding is one of the fundamental regulation mechanisms in biological events, such as molecular recognition and catalytic activity. The Trans conformation of the biindole moiety may be changed to the cis conformation, thereby significantly increasing the guest binding affinity. The stimuli-responsive conformational changes of photofunctional porphyrin derivatives are good for the design of molecular level photoswitching device.