Patent ID: 7576241

Claim:
A compound of the formula wherein A is in which R 18 , and R 19 and R 20 are, independently, selected from the group consisting of hydrogen, —OH or alkoxy of 1 to 6 carbon atoms; R 21 and R 22 are, independently, alkyl of 1 to 6 carbon atoms; X is —(CH 2 ) m —; Y is a bond or —(CH 2 ) n —; Φ is a bond or —(CH 2 ) p —NR 37 —(CH 2 ) q —; Z is —NO 2 ; R 39 is hydrogen; R 37 is alkyl of 1 to 6 carbon atoms; m and n are integers from 0 to 6, p is 1 and q is 2.