Molecular switch devices realised by photochromic oligothiophenes

In this report we describe a new chromene bearing at their three position terthiophene and quaterthiophene. These chromene-substituted oligothiophenes have been prepared by palladium-catalysed coupling reaction. When optically excited, these molecules undergo a structural change passing from a neutral state (closed form) to a strongly polarised one (open form). This photochromic process is also accompanied by a large increase in the electrical conductivity.