Patent ID: 7332610

Claim:
A compound of formula wherein A 1 is (R 7 )R 7′ N + Q − in which Q − is an anion and each of R 7 and R 7′ independently represents substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl, or two substituents R 7 together with the nitrogen atom to which they are attached and, optionally R 8 , form an unsubstituted or substituted heterocyclic group, or one R 7 substituent together with the nitrogen atom to which it is attached and the carbon atom to which the nitrogen atom is attached form an unsubstituted or substituted heterocyclic group; A 2 is O, S or NR 7c in which R 7c is substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; and each of R 8 , R 9 , R 10 and R 11 is independently hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted aralkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl, or R 8 and R 11 together form a substituted or unsubstituted alkylene or heteroalkylene chain, or a salt thereof.