Enhancement of molecular properties in thin films by controlled orientation of molecular building blocks.

We demonstrate the design and formation of thin films having divergent physicochemical properties by using two porphyrin building blocks with high chemical and optical resemblance. A predetermined variation in the molecular design is efficiently transferred and enhanced when constituting a two-dimensional film via control of molecular orientation. Variations of the peripheral substituents on the porphyrin ring resulted in control of the molecular orientation at the surface.