5003050

Claims

• We claim: 1. A luminescent compound having repeating units of the formula: ##STR3## 2. A method for preparing a luminescent compound having repeating units of the formula: ##STR4## which comprises the steps of (a) reacting 3-amino-L-tyrosine with an alkali metal nitrite to form a diazonium salt, (b) reacting said salt with 5-amino-2,3-dihydro-1,4-phthalazinedione and (c) recovering the resulting compound. 3. The method of claim 2 wherein said reacting step (a) is carried out in aqueous solution. 4. The method of claim 3 wherein said aqueous solution is acidic. 5. The method of claim 4 wherein said aqueous solution has a pH of about 5.0 to 6.0. 6. The method of claim 2 wherein said reacting step (a) is carried out for about 1 to 20 minutes. 7. The method of claim 6 wherein said reacting step (a) is carried out for about 5 to 10 minutes. 8. The method of claim 2 wherein said reacting step (a) is carried out at a temperature of about 0.degree. C. to room temperature. 9. The method of claim 2 wherein the amounts of said 3-amino-L-tyrosine and said alkali metal nitrite are approximately equimolar. 10. The method of claim 2 wherein said reacting step (b) is carried out for about 20 to 200 minutes. 11. The method of claim 2 wherein the molar ratio of 3-amino-L-tyrosine to 5-amino-2,3-dihydro-1,4-phthalazinedione is in the approximate range of 0.6:1 to 3:1. 12. The method of claim 11 wherein the amounts of said 3-amino-L-tyrosine and said 5-amino-2,3-dihydro-1,4-phthalazinedione are approximately equimolar.