Molecular switch devices realised by photochromic oligothiophenes

In this report we describe a new chromene bearing at their three position t erthiophene and quaterthiophene. These chromene-substituted oligothiophenes have been prepared by palladium-catalysed coupling reaction. When opticall y excited, these molecules undergo a structural change passing from a neutr al state (closed form) to a strongly polarised one (open form). This photoc hromic process is also accompanied by a large increase in the electrical co nductivity. (C) 2001 Elsevier Science B.V. All rights reserved.