Compound having formula II wherein X 1 to X 5 are independently of each other C, N or O, R 1, R 2 are independently of each other H, halogen, C alkyl, C alkenyl, C alkynyl, -OR 5, -COR 5, -COOR 5,-NHR 5, -CONHR 5, wherein R 5 represents H, halo, C alkyl, C alkenyl, C alkynyl, -OR', -COR',-COOR', or -NHR', wherein R' represents H or C alkyl, R 3, R 4 are independently of each other H, nitroso, C alkyl, -OR', -COR' or halosubstituted -COR', wherein R' represents H or C alkyl, Y 1, Y 2 are independently of each other O, N or S, m is 1, 2 or 3, r has a value of 1 to 7, p is 0 or 1, Q 1, Q 2 are independently of each other H, or a protecting group, wherein the protecting group is selected from t-butoxycarbonyl, benzyloxycarbonyl, allyloxycarbonyl, methoxy-, ethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, acetyl, trifluoroacetyl, benzyl, 2,4,6-trimethoxybenzyl, phthalolyl, trityl, tosyl, p-methoxyphenyl, 3,4-dimethoxybenzyl, benzyl, O-nitrobenzyl, di-(p-methoxyphenyl)methyl, triphenylmethyl, (p-methoxyphenyl)diphenylmethyl, diphenyl-4-pyridylmethyl, m-2-(picolyl)-N'-oxide, 5-dibenzosuberyl, trimethylsilyl, t-butyl-dimethylsilyl, methyl, t-butyl, methoxymethyl, thiomethyl, 2,2,2-trichloroethyl, p-methoxybenzyl, p-nitrobenzyl, diphenylmethyl, methyl ethers, MOM (methoxymethyl ether), MTM (methylthiomethyl ether), BOM (benzyloxymethyl ether), PMBM or MPM (p-methoxybenzyloxymethyl ether), TMS (trimethylsilyl ether), TES (triethylsilyl ether), TIPS (triisopropylsilyl ether), TBDMS (tert-butyldimethylsilyl ether), tribenzyl silyl ether and TBDPS (tert-butyldiphenylsilyl ether), or a group of formula -L-A-L'- 18 F, wherein L,L' are independently of each other a linking group, such as a covalent bond or a straight-chain or branched C alkyl, which is unsubstituted or substituted by at least one CN, Hal, OH, NH 2, CO 2 H, NO 2, and wherein one or more of the non-adjacent CH 2 groups may independently be replaced by a group selected from -O-, -CO-, -CO-O-, -O-CO-, -NR'-, -NR'-CO-, -CO-NR'-, -NR'-CO-O-, -O-CO-NR'-, -NR'-CO-NR'-, -CH=CH-, -C≡C-, -O-CO-O-, -S-R'-, -SO 3 R'-, or a five- or six-membered heterocycle, wherein R' represents H or C alkyl, and A is a saccharide group, with the proviso that at least one of Q 1 and Q 2 is a group of formula -L-A-L'- 18 F. X 1 to X 5 are independently of each other C, N or O, R 1, R 2 are independently of each other H, halogen, C alkyl, C alkenyl, C alkynyl, -OR 5, -COR 5, -COOR 5,-NHR 5, -CONHR 5, wherein R 5 represents H, halo, C alkyl, C alkenyl, C alkynyl, -OR', -COR',-COOR', or -NHR', wherein R' represents H or C alkyl, R 3, R 4 are independently of each other H, nitroso, C alkyl, -OR', -COR' or halosubstituted -COR', wherein R' represents H or C alkyl, Y 1, Y 2 are independently of each other O, N or S, m is 1, 2 or 3, r has a value of 1 to 7, p is 0 or 1, Q 1, Q 2 are independently of each other H, or a protecting group, wherein the protecting group is selected from t-butoxycarbonyl, benzyloxycarbonyl, allyloxycarbonyl, methoxy-, ethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl, acetyl, trifluoroacetyl, benzyl, 2,4,6-trimethoxybenzyl, phthalolyl, trityl, tosyl, p-methoxyphenyl, 3,4-dimethoxybenzyl, benzyl, O-nitrobenzyl, di-(p-methoxyphenyl)methyl, triphenylmethyl, (p-methoxyphenyl)diphenylmethyl, diphenyl-4-pyridylmethyl, m-2-(picolyl)-N'-oxide, 5-dibenzosuberyl, trimethylsilyl, t-butyl-dimethylsilyl, methyl, t-butyl, methoxymethyl, thiomethyl, 2,2,2-trichloroethyl, p-methoxybenzyl, p-nitrobenzyl, diphenylmethyl, methyl ethers, MOM (methoxymethyl ether), MTM (methylthiomethyl ether), BOM (benzyloxymethyl ether), PMBM or MPM (p-methoxybenzyloxymethyl ether), TMS (trimethylsilyl ether), TES (triethylsilyl ether), TIPS (triisopropylsilyl ether), TBDMS (tert-butyldimethylsilyl ether), tribenzyl silyl ether and TBDPS (tert-butyldiphenylsilyl ether), or a group of formula -L-A-L'- 18 F, wherein L,L' are independently of each other a linking group, such as a covalent bond or a straight-chain or branched C alkyl, which is unsubstituted or substituted by at least one CN, Hal, OH, NH 2, CO 2 H, NO 2, and wherein one or more of the non-adjacent CH 2 groups may independently be replaced by a group selected from -O-, -CO-, -CO-O-, -O-CO-, -NR'-, -NR'-CO-, -CO-NR'-, -NR'-CO-O-, -O-CO-NR'-, -NR'-CO-NR'-, -CH=CH-, -C≡C-, -O-CO-O-, -S-R'-, -SO 3 R'-, or a five- or six-membered heterocycle, wherein R' represents H or C alkyl, and A is a saccharide group, with the proviso that at least one of Q 1 and Q 2 is a group of formula -L-A-L'- 18 F.