Two homologous series

ono with a chalcone central linkage (Series Ⅰ) and other the esters of the series Ⅰ (Series Ⅱ) have been synthesised. Three compounds from each series have been inyestigatcd for their luminescent behaviour. All the members of both series show fluorescence. It is observed that the 360 nm emission which is present in series I compounds is absent in the emission spactra for series Ⅱ compounds. However

another emission at 470 nm is observed in compounds of both series. It has bean concluded that hydrogen bond which removes the perturbing effect of the non-bonding electron is responsible for the presence of 360 nm emission in the compounds of Series Ⅰ.