Alexa Fluor 647 C2-Maleimide 6C is a maleimide-functionalized derivative of Alexa Fluor 647, emitting far-red fluorescence with excitation/emission maxima around 651/670 nm. Its maleimide group specifically reacts with thiol (-SH) groups in proteins or peptides, enabling efficient labeling of cysteine residues and other thiol-containing molecules. This dye is widely used in cell biology, neuroscience, and disease research as a functional far-red fluorescent probe.