Because of their widespread occurrence in nature (7-3), their medicinal properties (4-70), and their use as optical brighteners (7 7-77), coumarins have long occupied the interest of synthetic chemists (78-20). In the last few years 7hYdrOXyand 7-aminocoumarins have received increased attention because of their applications as laser dyes (27-24). Even more recently thelr fluorescence properties have been used to advantage in substrates for the ...
