Oxazine 1

Oxazine 1 is one of the most fluorescent NIR dyes. It has maximum absorption around 650 nm with extinction coefficient larger than 100,000 M-1 cm-1. It has fluorescence emission around 670 nm, which is pH-independent. Although Oxazine 1 is quite stable from pH 4 to pH 10, it might be reduced by some biological molecules (such as DTT, GSH etc) at high concentration. Oxazine 1 is also an efficient laser dye tunable around 670 nm.