Use of compounds which absorb and/or fluoresce in the IR region as markers for liquids

A method of identifying a liquid comprising the sequential steps of:

• (i) detecting a marker compound in a liquid;
• and
• (ii) identifying said liquid based on the identity of said marker compound,
• wherein said marker compound exhibits an absorption maximum in the range of 600-1,200 nm and/or a fluorescence maximum in the range of 620-1,200 nm, and
• wherein said marker compound is a compound of Formula Ia, Ib, III, IV, V or VI, ##STR51## where Me.sup.1 is two hydrogen atoms, two lithium atoms or magnesium, zinc, copper, nickel, VO, TiO, AlCl or Si(OH).sub.2, at least 4 of the radicals R.sup.1 to R.sup.16, independently of one another, have the formula W-X.sup.1 in which W is a chemical bond, sulfur, imino, C.sub.1 -C.sub.4 -alkylimino or phonylimino, and X.sup.1 is C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function or substituted by phenyl, or are adamantyl or substituted or unsubstituted phenyl, and
• any remaining radicals R.sup.1 to R.sup.16 are hydrogen, halogen, hydroxysulfonyl or C.sub.1 -C.sub.4 -dialkylsulfamoyl), ##STR52## where R.sup.17 and R.sup.18 or R.sup.18 and R.sup.19 or R.sup.19 and R.sup.20 together in each case have the formula X.sup.2 -C.sub.2 H.sub.4 -X.sup.3, in which one of the two radicals X.sup.2 and X.sup.3 is oxygen and the other is imino or C.sub.1 -C.sub.4 -alkylimino, and
• R.sup.19 and R.sup.20 or R.sup.17 and R.sup.20 or R.sup.17 and R.sup.18, independently of one another, are in each case hydrogen or halogen, and
• Me.sup.1 is as defined above, ##STR53## where Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4, Y.sup.5, Y.sup.6, Y.sup.7 and Y.sup.8, independently of one another, are each hydrogen, hydroxyl, C.sub.1 -C.sub.20 -alkyl or C.sub.1 -C.sub.20 -alkoxy, where the alkyl groups may each be interrupted by from 1 to 4 oxygen atoms in ether function and may be substituted by phenyl,
• Y.sup.9, Y.sup.10, Y.sup.11 and Y.sup.12, independently of one another, are each hydrogen, C.sub.1 -C.sub.20 -alkyl or C.sub.1 -C.sub.20 -alkoxy, where the alkyl groups may each be interrupted by from 1 to 4 oxygen atoms in ether function, or are halogen, hydroxysulfonyl or C.sub.1 -C.sub.4 -dialkylsulfamoyl, and
• Me.sup.2 is two hydrogen atoms, two lithium atoms, magnesium, zinc, copper, nickel, VO, TiO, AlCl or ##STR54## where Y.sup.17 and Y.sup.18, independently of one another, are each hydroxyl, C.sub.1 -C.sub.20 -alkoxy, C.sub.1 -C.sub.20 -alkyl, C.sub.2 -C.sub.20 -alkenyl, C.sub.3 -C.sub.20 -alkenyloxy or ##STR55## in which Y.sup.19 is C.sub.1 -C.sub.20 -alkyl, C.sub.2 -C.sub.20 -alkenyl or C.sub.4 -C.sub.20 -alkadienyl and Y.sup.20 and Y.sup.21, independently of one another, are each C.sub.1 -C.sub.12 -alkyl, C.sub.2 -C.sub.12 -alkenyl or as defined for OY.sup.19 above, ##STR56## where L.sub.1, L.sup.2, L.sup.3 and L.sup.4, independently of one another, are each C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function, phenyl, C.sub.1 -C.sub.20 -alkylphenyl, C.sub.1 -C.sub.20 -alkoxyphenyl, where the alkyl groups may each be interrupted by from 1 to 4 oxygen atoms in ether function, or L.sup.1 and L.sup.2 and/or L.sup.3 and L.sup.4 in each case together are ##STR57## where Z.sup.1, Z.sup.2, Z.sup.3 and Z.sup.4, independently of one another, are each C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function, C.sub.1 -C.sub.20 -alkanoyl or ##STR58## where Z.sup.4 is hydrogen, C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function, or C.sub.1 -C.sub.20 -alkanoyl, Z.sup.7 is hydrogen or C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function, and Z.sup.8 is hydrogen, C.sub.1 -C.sub.20 -alkyl, which may be interrupted by from 1 to 4 oxygen atoms in ether function, or halogen, and
• An.sup..crclbar. is the equivalent of an anion, ##STR59## in which the rings A and B, independently of one another, may each be benzo-fused and/or substituted,
• E.sup.1 and E.sup.2, independently of one another, are each oxygen, sulfur, imino, --C(CH.sub.3).sub.2 -- or --CH.dbd.CH--,
• D is ##STR60## where E.sup.3 is hydrogen, C.sub.1 -C.sub.6 -alkyl, chlorine or bromine and E.sup.4 is hydrogen or C.sub.1 -C.sub.6 -alkyl,
• Q.sup.1 and Q.sup.2, independently of one another, are each phenyl, C.sub.5 -C.sub.7 -cycloalkyl, C.sub.1 -C.sub.12 -alkyl, which may be interrupted by from 1 to 3 oxygen atoms in ether function and may be substituted by hydroxyl, chlorine, bromine, carboxyl, C.sub.1 -C.sub.4 -alkoxycarbonyl, acryloyloxy, methacryloyloxy, hydroxysulfonyl, C.sub.1 -C.sub.7 -alkanoylamino, C.sub.1 -C.sub.6 -alkylcarbamoyl, C.sub.1 -C.sub.6 -alkylcarbamoyloxy or G.sup.e (K).sub.3, where G is nitrogen or phosphorus and K is phenyl, C.sub.5 -C.sub.7 -cycloalkyl or C.sub.1 -C.sub.12 -alkyl,
• An.sup..crclbar. is the equivalent of an anion, and
• n is 1, 2 or 3, ##STR61## where J is C.sub.1 -C.sub.12 -alkylene,
• T.sup.1 is hydrogen, halogen, amino, hydroxyl, C.sub.1 -C.sub.12 -alkoxy, phenyl, substituted phenyl, carboxyl, C.sub.1 -C.sub.12 -alkoxycarbonyl, cyano, -NT.sup.7 -CO-T.sup.6, -CO-NT.sup.6 T.sup.7 or -O-CO-NT.sup.6 T.sup.7, where T.sup.6 and T.sup.7, independently of one another, are each hydrogen, C.sub.1 -C.sub.12 -alkyl, C.sub.5 -C.sub.7 -cycloalkyl, phenyl, 2,2,6,6-tetramethylpiperidin-4-yl or cyclohexylaminocarbonyl, and
• T.sup.2, T.sup.3, T.sup.4 and T.sup.5, independently of one another, are each hydrogen or C.sub.1 -C.sub.12 -alkyl, which may be substituted by halogen, amino, C.sub.1 -C.sub.12 -alkoxy, phenyl, substituted phenyl, carboxyl, C.sub.1 -C.sub.12 -alkoxycarbonyl or cyano,
• with the proviso that, if T.sup.5 is hydrogen, the ring positions of the substituents J-T.sup.1 and T.sup.4 within an azulene ring may also be exchanged for one another on one or both azulene rings.