Maldi-ms method, photo-sensitive maldi matrix composite and photo-caged maldi matrix compound for use in said method and respective uses

Photo-caged MALDI Matrix Compound for use in a method of matrix-assisted laser desorption/ionization mass spectrometry, comprising or consisting of:

• a Photoremovable Protecting Group Moiety B which is covalently bonded to an organic MALDI Matrix Compound Moiety A,
• wherein
• the organic MALDI Matrix Compound Moiety A is a moiety selected from the group consisting of
• a moiety of formula I-1
• wherein
• R1a and R1b are both independently of each other selected from the group consisting of hydrogen, hydroxy, carboxy, methyl and methoxy,
• R2 is selected from the group consisting of hydroxy and methyl and
• X is selected from the group consisting of oxygen, —N(H)—, —N(CH3)— and —N(C2H5)—,
• wherein the moiety of formula I-1 is attached to the Photoremovable Protecting Group Moiety B via the free bond to the right of group X;
• a moiety of formula I-2
• wherein
• R3 and R4 are independently of each other selected from the group consisting of hydrogen, hydroxy, halogen and methoxy and
• R5 is selected from the group consisting of hydroxy, methyl and cyano and
• R10 is selected from the group consisting of hydroxy and methyl,
• wherein the moiety of formula I-2 is attached to the Photoremovable Protecting Group Moiety B via the free bond to the right of the oxygen atom attached to the phenyl ring;
• a moiety of formula I-3
• wherein
• G is selected from the group consisting of nitrogen and C—H;
• R6 is selected from the group consisting of hydrogen and amino,
• R7 and R8 are independently of each other selected from the group consisting of hydrogen, amino and methyl, or together with the carbon atoms to which they are bonded, form a saturated or unsaturated five or six-membered ring,
• R9 is selected from the group consisting of hydrogen, phenyl, branched or unbranched, saturated alkyl having 1 to 4 carbon atoms and branched or unbranched, saturated aminoalkyl having 1 to 4 carbon atoms, and
• R11 is a bond or hydrogen,
• wherein the moiety of formula I-3 is covalently bonded to the Photoremovable Protecting Group Moiety B via a free bond of a nitrogen atom present in the moiety of formula I-3;
• and
• a moiety which is selected from the group consisting of the moieties of formula I-4, formula I-5 and formula I-6:
• wherein the moieties of formula I-4 and of formula I-6 are attached to the Photoremovable Protecting Group Moiety B via the respective free bond of an oxygen atom, and wherein the moiety of formula I-5 is attached to the Photoremovable Protecting Group Moiety B via the free bond of a sulfur atom;
• and wherein
• the Photoremovable Protecting Group Moiety B is a moiety of formula II
• wherein
• R12 is selected from the group consisting of hydrogen and branched or unbranched, saturated alkyl with 1 to 4 carbon atoms;
• R13 is selected from the group consisting of hydrogen, branched or unbranched, saturated alkyl with 1 to 4 carbon atoms and carboxy;
• R14 and R15 are attached to the phenyl ring, wherein
• R14 and R15 are both independently of each other selected from the group consisting of hydrogen, methoxy, carboxy, nitro and —O(CH2)ICOOH, wherein 1 is an integer in the range from 1 to 3;
• or
• R14 and R15 together form an acetal group having two oxygen atoms attached to adjacent carbon atoms of the phenyl ring and having 1 to 3 carbon atoms outside the phenyl ring;
• R16 and R11 are hydrogen or, together with the carbon atom to which they are bonded, form a carbonyl group;
• and
• m, n, and p are independently of each other 0 or 1, wherein preferably n=0 and wherein the Photoremovable Protecting Group Moiety B of formula II is attached to an organic MALDI Matrix Compound Moiety A via the free bond next to the letter “p” shown in formula II above.