Patent ID: 8557804

Claim:
A compound of formula: wherein R 1 and R 2 are independently lower alkyl of 1 to 10 carbon atoms, Xa is CH or N, Ya is one or more substituent selected from hydrogen, halogen, amidino, amido, azido, cyano, guanido, hydroxyl, nitroso, urea, sulfate, sulfite, sulfonate, sulphonamide, phosphate, phosphonate, acyl, acyloxy, alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, alkylthio of 1 to 6 carbon atoms, alkylamino of 1 to 6 carbon atoms, alkanol of 1 to 6 carbon atoms, and aralkyl, n is 2, J is a counter ion.