Redox activatable fluorescent sensors

A compound of the formula:

• wherein:
• R1 is a first label, amino, hydroxy, alkoxy(C≤8), substituted alkoxy(C≤8), alkylamino(C≤8), substituted alkylamino(C≤8), dialkylamino(C≤8), substituted dialkylamino(C≤8), an amine reactive group;
• a thiol reactive group, an organic polymer, a nucleic acid sequence, a peptide, or a protein;
• R2 is a first label, hydrogen, alkyl(C≤8), substituted alkyl(C≤8), an organic polymer, a nucleic acid sequence, a peptide, or a protein;
• R3 is a second label;
• and
• m and n are each independently 0, 1, 2, or 3;
• provided that either R1 or R2 is a first label.