Bioorthogonal compositions

A compound of formula (I),

• or a pharmaceutically acceptable salt thereof,
• wherein:
• D is a chelated radionuclide;
• L is a linker;
• R1, at each occurrence, is independently selected from the group consisting of halogen, cyano, nitro, alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, heterocycle, cycloalkyl, cycloalkenyl, —OR1a, —NR1bR1c, —SR1d, —SO2R1e, —S(O)R1f, and —P(O)OR1gR1h;
• R1a, R1b, R1c, R1d, R1e, R1f, R1g, and R1h, are each independently selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, heterocycle, cycloalkyl, and cycloalkenyl;
• and
• n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13;
• wherein said alkyl, alkenyl, alkynyl, heteroalkyl, aryl, heteroaryl, heterocycle, cycloalkyl, and cycloalkenyl, at each occurrence, are independently substituted with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 substituents, each independently selected from the group consisting of halogen, ═O, ═S, cyano, nitro, fluoroalkyl, alkoxyfluoroalkyl, fluoroalkoxy, alkyl, alkenyl, alkynyl, haloalkyl, haloalkoxy, heteroalkyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocycle, cycloalkylalkyl, heteroarylalkyl, arylalkyl, hydroxy, hydroxyalkyl, alkoxy, alkoxyalkyl, alkylene, aryloxy, phenoxy, benzyloxy, amino, alkylamino, dialkylamino, acylamino, aminoalkyl, arylamino, sulfonylamino, sulfinylamino, sulfonyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl, sulfinyl, —COOH, ketone, amide, carbamate, silyl, substituted silyl, t-butyldimethylsilyl, alkylsulfanyl, sulfanyl, and acyl.