Novel benzophenone-based chromophoric crosslinkers and reagents for incorporation of biotin or other haptens into macromolecules

A spectrophotometrically quantifiable linker comprising of formula:

• R1-L1-C-L2-R2
• wherein,
• R1 and R2 are the same or different and are each independently selected from the group consisting of —O—, —OH, —SH, —NH, —NH2, —F, —Cl, —Br, —I, O-Su (N-hydroxysuccinimidyl, sulfo-N-hydroxysuccinimidyl), —O-STP (4-sulfo-2,3,5,6,-tetrafluorophenyl), —O-TFP (2,3,5,6-pentafluorophenyl), —O-benzotriazole, benzotriazole, —CO—CH2—I, —NR-biomolecule (wherein the biomolecule is a peptide, protein, antibody, nucleotide, or oligonucleotide), —COO—, —COOH, —CO—NH—NH2, —O-phosphoramidite, —CHO, -maleimide, pyridylsulfide, —O—NH2 (aminoxy), —N3, terminal alkyne, nonbornene, trans-cyclooctene, cyclooalkyne, dibenzocyclooctyne, tetrazine, biotin, desthiobiotin, digoxigenin, and hapten;
• L1 and L2 are the same or different and are independently selected from the group consisting of a divalent linear —(CH2)x- group, or —(CH2CH2O)x— group, wherein x is 1 to 25, a branched or cyclic alkane group, which is optionally substituted by at least one atom selected from the group consisting of oxygen, substituted nitrogen, and sulfur;
• and
• C is a chromophoric benzophenone moiety.