Compositions, methods, and systems for the synthesis and use of imaging agents

A composition comprising a compound comprising formula (II):

• or a salt, free base, or combination thereof, wherein:
• R1 is alkyl, haloalkyl, alkynyl, alkenyl, heteroalkyl, cycloalkyl, aryl, heteroaryl, arylalkyl, heterocyclyl, or heteroarylalkyl, each optionally substituted;
• each R2 is hydrogen;
• R3, R4, R5, and R6 can be the same or different and are individually hydrogen, C1-C6 alkyl, heteroalkyl, halide, —OR7, —SR7, —N(R7)2, or —C(═O)R8, each optionally substituted;
• each R7 can be the same or different and is hydrogen, alkyl, heteroalkyl, cycloalkyl, heterocyclyl, haloalkyl, aryl, or heteroaryl, each optionally substituted;
• each R8 can be the same or different and is hydrogen, alkyl, heteroalkyl, cycloalkyl, haloalkyl, heterocyclyl, aryl, heteroaryl, —OH, alkoxy, —NH2, alkylamino, —SH, or alkylthiol, each optionally substituted;
• m is an integer between 1 and 12, inclusive;
• and
• n is an integer between 1 and 4, inclusive.