| abstract |
Process employing bipyridyls as inks, of the general formula ##STR1## in which R, R' are, for example, alkyl and R 1 , R 2 , R 3 , R 4 , R 5 , R 6 are, for example hydrogen or alkyl radicals, or R 1 and R 2 or R 2 and R 3 , and/or R 4 and R 5 or R 5 and R 6 together with the pyridine ring form in isoquinoline or quinoline ring system. |