The successful design of photochromic self-assembly systems requires understanding (on both the molecular and sub-molecular scales) of diverse and often competing structure-property relationships. Such molecular systems are promising as components for photonically switchable components in opto-electronic devices. Molecular modularisation can be an efficient approach to obtain such materials. The design, synthesis and the photochromic and mesomorphic properties of stable photochromic systems which exhibit nematic LC phase behaviour at room temperature are reported. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).