Supramolecular chirality induced by a weak thermal forceElectronic supplementary information (ESI) available: Materials and methods, light scattering and circular dichroism data at different temperature values, evaluation of the linear dichroism contribution. See DOI: 10.1039/c3sm52322e

We show that the unexpected chirality of aggregated structures based on an uncharged achiral porphyrin system originates from small temperature gradients that act as an asymmetrical physical perturbation; the consequent thermal force gives rise to the thermophoretic motion of the aggregates. We establish that the induced optical activity can be controlled, and even vanished, by minimizing the thermal force. The unexpected chirality of supramolecular aggregates of achiral porphyrins originates from small temperature gradients that act as an asymmetrical physical perturbation.