Synthesis of Novel Iono- and Photochromic Spiropyrans Derived from 6,7-Dihydroxy-8-Formyl-4-Methyl-2H-Chromene-2-One

Table 1

Long-wavelength maxima of (4) and parameters of (4A)-(4B) equilibrium in chloroform at 293 K.

Comp.	Absorption of (4), 𝜆max, (nm), (𝜀×10^−4, 1 mol^−1 cm^−1)	Content of form B,%	𝐾^𝑜= [B]/[A]
4a	448 (2.31), 595 (1.72)	28.6	0.401
4b	447 (2.35), 595 (1.78)	56.5	1.299
4c	447 (2.40), 596 (1.82)	23.5	0.307
4d	452 (3.07), 605 (2.04)	9.0	0.099
4e	448 (1.85), 593 (1.63)	63.0	1.702
4f	—	0	—