Protecting groups with increased photosensitivities

A compound of formula

• wherein:
• A is —OH, —OC(O)CH3, NH2, or —NHCH3;
• each of X1 and X2, independently, is H, Cl, Br, or I, with at least one of X1 and X2 being Cl, Br, or I;
• Q is —O—,—NH—, or —NCH3—;
• Y1 is —H, —Cl, —Br, —I, —C(O)OH, —NO2, —C(O)NHR1, —CN, —C(O)H, —C(O)CH3, benzoxazol-2-yl, benzothiazol-2-yl, or benzimidazol-2-yl;
• Y2 is —H, —C(O)OH, or —SO3H;
• M1 is —H, —CH3, —NR2R3, —C(O)NR2R3, or —COOH;
• Z is —Cl, —Br, —I—, —OH, —OC(O)R4, —OP(O)R5R6 and M2 is —H;
• or Z and M2 together are ═N2, ═O, or ═NNHR1;
• each of R1, R2, and R3, independently, is a substituted or unsubstituted moiety selected from the group consisting of a C1-20 alkyl, a C2-20 alkenyl, a C2-20 alkynyl, a C1-20 alkoxy, a C1-20 thioalkoxy, a C1-20 alkylsulfonyl, a C4-16 arylsulfonyl, a C2-20 heteroalkyl, a C2-20 heteroalkenyl, a C3-8 cycloalkyl, a C3-8 cycloalkenyl, a C4-16 aryl, a C4-16 heteroaryl, and a C2-30 heterocyclyl;
• and
• each of R4, R5, and R6 independently, is a substituted or unsubstituted moiety selected from the group consisting of a C1-20 alkyl, a C2-20 alkenyl, a C4-16 aryl, a C2-20 heteroalkyl, an amino acid radical, a peptide radical, a polynucleotide radical, and a nucleoside radical or R5 and R6 together can form a nucleoside diradical;
• or a salt thereof.