Tuning the effective molecular diffusion: a step toward control over oriented molecular motion

Publication Type:

Journal Article

Source:

ACTUALITE CHIMIQUE, SOC FRANCAISE CHIMIE, Number Suppl. 284, 250 RUE SAINT-JACQUES, 75005 PARIS, FRANCE, p.9-15 (2005)

Keywords:

BROWNIAN PARTICLES; COMPLEXITY; WORLD

Abstract:

<< Control >> over disordered molecular motion is not a dream as clearly evidenced by living beings. In the reactive mixture of cell cytoplasm, molecules perform an oriented ballet. Astonishment of the chemist should not here originate only from the motion, but much more from its orientation as well as from its selectivity. Much has to be analyzed and a lot has to be imagined to account for this observation. We attempt to reproduce a few basic features of biological motors in simpler, << molecular cargos >>. This goal is difficult. We first chose to exert an analogous control over molecular motion in a less compelling situation, that of diffusion: the orientation of motion is lost, in contrast selectivity is maintained. We recently demonstrated that it is possible to << fish >> any reactant in a mixture submitted to the action of an appropriate uniform and time-periodic field when its period is matched to the lifetimes of the interconverting states of the desired reactant. Under such conditions, the effective diffusion of the latter can be considerably increased and it becomes possible to selectively perform its extraction.