A compound of the formula: and pharmaceutically acceptable salts and stereoisomers thereof, wherein: L is N or CR 5; M is N; R 5 is H, OH, halo, NH 2, CH 3, NO 2, aryl, C 3 -C 8 alkenyl, C 3 -C 8 alkynyl, C 3-8 cycloalkyl, heteroaryl, N=NR 12, NHR 12, N(R 12) 2, or (-CH 2) 1-12 -R 12, wherein R 12 is C 1 -C 6 alkyl, aryl, H or heteroaryl, wherein at least one H of (-CH 2) 1-12 -R 12, C 3-8 cycloalkyl, aryl, alkenyl, alkynyl, or heteroaryl, is optionally replaced by halo, OH, NH 2, and C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of (-CH 2) 1-12 -R 12 is optionally replaced with C, O, S, SO 2, or NH, NH-C 1-8 alkyl or N(C 1-8 alkyl) 2, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced by C, O, S, NH or N-C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo or OH, X is a bond or is C 1-14 alkyl, wherein at least one carbon is optionally replaced by C, O, S, SO 2, or NH, NH-C 1-8 alkyl, and wherein at least one H of C 1-8 alkyl is optionally replaced by halo, OH, C 1-6 alkyl; R 9 is H, an azide, an alkyne, OH, halo, NH 2, N(C 1-8 alkyl) 2, aryl or heteroaryl, wherein at least one H of the aryl or heteroaryl is optionally replaced by halo, NH 2, or C 1-6 alkyl or C 1-6 alkyl, wherein at least one H of the C 1-6 alkyl is optionally replaced by halo, or C 3-8 cycloalkyl, wherein at least one H of the C 3-8 cycloalkyl is optionally replaced by halo and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced with O, OH, S, SH, NH, N-C 1-8 alkyl; R 3 is a bond or is at least one of O, S, C, SO 2, NH, N-C 1-8 alkyl, (CH 2) 1-12, wherein at least one C of (CH 2) 1-12 is optionally replaced by C, O, S, SO 2, NH, N-C 1-8 alkyl and wherein at least one H is optionally replaced by C 1-8 alkyl or halo, R 20 is aryl or heteroaryl; and R 21 is H, OH, halo, NH 2, CH 3, NO 2,, (-CH 2) 1-12 -CH 3, or C 3-8 cycloalkyl, wherein at least one H of the (-CH 2) 1-12 -CH 3 or the C 3-8 cycloalkyl is optionally replaced by halo, OH, NH 2, or C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo or OH, and wherein at least one CH 2 of the (-CH 2) 1-12 -CH 3 is optionally replaced with C, O, S, SO 2, or NH, NH-C 1-8 alkyl, N(C 1-8 alkyl) 2, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced by C, O, S, SO 2, or NH, N-C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein R 21 comprises a radionuclide, provided that the compound is not L is N or CR 5; M is N; R 5 is H, OH, halo, NH 2, CH 3, NO 2, aryl, C 3 -C 8 alkenyl, C 3 -C 8 alkynyl, C 3-8 cycloalkyl, heteroaryl, N=NR 12, NHR 12, N(R 12) 2, or (-CH 2) 1-12 -R 12, wherein R 12 is C 1 -C 6 alkyl, aryl, H or heteroaryl, wherein at least one H of (-CH 2) 1-12 -R 12, C 3-8 cycloalkyl, aryl, alkenyl, alkynyl, or heteroaryl, is optionally replaced by halo, OH, NH 2, and C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of (-CH 2) 1-12 -R 12 is optionally replaced with C, O, S, SO 2, or NH, NH-C 1-8 alkyl or N(C 1-8 alkyl) 2, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced by C, O, S, NH or N-C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo or OH, X is a bond or is C 1-14 alkyl, wherein at least one carbon is optionally replaced by C, O, S, SO 2, or NH, NH-C 1-8 alkyl, and wherein at least one H of C 1-8 alkyl is optionally replaced by halo, OH, C 1-6 alkyl; R 9 is H, an azide, an alkyne, OH, halo, NH 2, N(C 1-8 alkyl) 2, aryl or heteroaryl, wherein at least one H of the aryl or heteroaryl is optionally replaced by halo, NH 2, or C 1-6 alkyl or C 1-6 alkyl, wherein at least one H of the C 1-6 alkyl is optionally replaced by halo, or C 3-8 cycloalkyl, wherein at least one H of the C 3-8 cycloalkyl is optionally replaced by halo and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced with O, OH, S, SH, NH, N-C 1-8 alkyl; R 3 is a bond or is at least one of O, S, C, SO 2, NH, N-C 1-8 alkyl, (CH 2) 1-12, wherein at least one C of (CH 2) 1-12 is optionally replaced by C, O, S, SO 2, NH, N-C 1-8 alkyl and wherein at least one H is optionally replaced by C 1-8 alkyl or halo, R 20 is aryl or heteroaryl; and R 21 is H, OH, halo, NH 2, CH 3, NO 2,, (-CH 2) 1-12 -CH 3, or C 3-8 cycloalkyl, wherein at least one H of the (-CH 2) 1-12 -CH 3 or the C 3-8 cycloalkyl is optionally replaced by halo, OH, NH 2, or C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo or OH, and wherein at least one CH 2 of the (-CH 2) 1-12 -CH 3 is optionally replaced with C, O, S, SO 2, or NH, NH-C 1-8 alkyl, N(C 1-8 alkyl) 2, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein at least one CH 2 of the C 3-8 cycloalkyl is optionally replaced by C, O, S, SO 2, or NH, N-C 1-8 alkyl, wherein at least one H of the C 1-8 alkyl is optionally replaced by halo, OH or NH 2, and wherein R 21 comprises a radionuclide, provided that the compound is not