Seven novel diacetylenes have been synthesised, with six of these containing a pyridine ring directly conjugated to the main diacetylene unit. Values of chi(2) and chi(3) for these diacetylenes as guests in a guest-host polymer matrix (polysiloxane) have been obtained. High values of chi(2) are shown to depend on the presence of the pyridine ring whereas the highest values of chi(3) are obtained for the lesser conjugated diacetylenes.