Abstract: Use of compounds from the class of the phthalocyanines, naphthalocyanines, nickel dithiolene complexes, aminium compounds of aromatic amines, methine dyes or azulenesquaric acid dyes which have their absorption maximum in the range from 600 to 1,200 nm and/or a fluorescence maximum in the range from 620 to 1,200 nm, as markers for liquids, a process for detecting markers in liquids, and a detector suitable for this purpose.

Abstract: Use of compounds from the class of the phthalocyanines, naphthalocyanines, nickel dithiolene complexes, aminium compounds of aromatic amines, methine dyes or azulenesquaric acid dyes which have their absorption maximum in the range from 600 to 1,200 nm and/or a fluorescence maximum in the range from 620 to 1,200 nm, as markers for liquids, a process for detecting markers in liquids, and a detector suitable for this purpose.

Abstract: A process is described for preparing alkoxy-octasubstituted metal-free or metal-containing naphthalocyanines by etherification of 1,4-dihydroxy-2,3-dicyanonaphthalene and formation of the metal-free naphthalocyanine with or without subsequent metallization.

Abstract: Ink ribbons containing one or more compounds from the group comprising phthalocyanines, the naphthalocyanines, the nickel dithiolene complexes, the methine dyes and the azulene quaternary-acid dyes, all of which have their absorption maximum in the region from 700 to 1,200 nm.

Abstract: Naphthalocyanines of the general formula I ##STR1## where the variables have the following meanings: R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are each independently of the others hydrogen, hydroxyl or C.sub.1 -C.sub.20 -alkyl or C.sub.1 -C.sub.20 -alkoxy, whose carbon chains may each be interrupted by from 1 to 4 oxygen atoms in ether function and which may be phenyl-substituted,R.sup.9, R.sup.10, R.sup.11 and R.sup.12 are each independently of the others hydrogen, halogen or C.sub.1 -C.sub.20 -alkyl or C.sub.1 -C.sub.20 -alkoxy, whose carbon chains may each be interrupted by from 1 to 4 oxygen atoms in ether function,Me is two hydrogen atoms, two univalent metal atoms or a bivalent metal atom with or without further substituents for valence saturation,are pigments with isometric particles and a particle size distribution from 10 to 300 nm.

Abstract: A liquid useful as printing ink contains one or more dyes with their absorption maximum within the range from 700 to 1200 nm selected from the phthalocyanines, the naphthalocyanines, the nickel-dithiolene complexes, the aminium compounds of aromatic amines, the methine dyes or the azulenesquaric acid dyes, as well as solvent and binder.