This is a non-aqueous redox-flow-battery redoxmer candidate. Attaching different chemical groups to the core molecular structure can alter the absorption wavelength differences. The Product is {product}. The R1 substituent is {r1_label}. The R3 substituent is {r3_label}. The R4 substituent is {r4_label}. The R5 substituent is {r5_label}. What is the the absorption wavelength difference of this redoxmer?