We probe the fluorescence from single molecules of a new class of tetrahedral oligo(phenylenevinylene) (OPV) molecules. Our results show that the tetrahedral molecules contain multiple chromophores with limited inter-arm coupling, but significant molecular motion about the central carbon results in fluctuations in the polarizability axis of the molecule, Loss in luminescence intensity is also observed during the fluctuations which is attributed to inter-arm coupling occurring when adjacent arms come close together. These fluctuations occur on the timescale of 100 ms to 10 s and are shown to be absent in the 'arm' molecules alone, (C) 2002 Elsevier Science B.V, All rights reserved.