2,5-PRODAN: synthesis and properties

The preparations of 1-(6-(dimethylamino)naphthalen-1-yl)propan-1-one (2,5-PRODAN, 2) and 7-(dimethylamino)-2,3-dihydrophenanthren-4(1H)-one 3 are described. The photophysical properties of these compounds are characterized and compared with those of PRODAN. Both compounds show solvatochromism that is similar in magnitude to PRODAN with a quantum yield that is nearly one order of magnitude smaller. Emission occurs from a locally excited (LE) state with charge-transfer character. There is no internal conversion to a different charge-transfer state as is seen in PRODAN.