Below 24 mM a constant viscosity with a slope of 2.3 was observed for (Z)-III. Above the critical concentration the slope changes to 4.4. The viscosities for (E)-III increased steadily with concentration with a slope of 2.7. An inflection point for the critical concentration denoting transition from the cyclic to oligomeric regime in the double logarithmic plot was observed ~ 24 mM at which point the slope increased to 3.2 (Fig. ). Overall, the viscosity data for III indicate similar ring-chain behaviour to that observed for II with the Z isomer exhibiting a greater tendency than the E isomer towards ring formation below the critical concentration (24 mM) and then above the critical concentration, both isomers oligomerizing with the E isomer forming more viscous assemblies. In each case the E and Z isomers of III are more viscous than the corresponding E and Z isomers of II in the higher concentration regime, which is consistent with the DOSY results which indicated III forms longer polymers than II.