Patent ID: 7641726

Claim:
A mixture of compounds of Formula (1) and salts thereof: wherein: M is 2H, Si, a metal, an oxymetal group, a hydroxymetal group or a halometal group; Pc represents a phthalocyanine nucleus of formula; R 1 is H or optionally substituted C 1-4 alkyl; R 2 is optionally substituted alkyl; R 3 is H or optionally substituted C 1-4 alkyl; R 4 is a group which comprises a component which is optionally substituted heterocyclyl; L is a direct covalent bond or a divalent linking group; w, x, y and z are each independently greater than zero; the substituents represented by y and z are different; and the sum of w+x+y+z is in the range of 2 to 4.