Exciton dynamics in a one-dimensional self-assembling lyotropic discotic liquid crystal

The steady state and time resolved phophysical properties of a novel self-assembling lyotropic discotic liquid crystal, 2.3,6,7, 10,11-hexa-(1,4.7-trioxaoctyl)-triphenylene (TP6EO2M) are reported. The spectral changes that accompany the formation of linear aggregates in D2O provide no evidence of excited-state delocalization, and the evidence suggests only a very weak interaction between neighboring molecules. Time resolved fluorescence depolarization measurements support a picture of a mobile exciton that hops along the columnar aggregates at a rate of at least 10(11) s(-1). Since the system comprises an isotropic solution of columnar aggregates, the exciton motion is likely to be highly one dimensional. Doping of the molecular aggregates introduces extrinsic trap sites allowing a simple I-D hopping model to be used to analyze the long time fluorescence decay kinetics. Fitting the data obtained from samples doped,with trinitrofluoronone indicates that this lyotropic system has an order of magnitude higher concentration of intrinsic traps in the isotropic phase than its thermotropic analogues display in the columnar mesophase.