Synthesis and optical properties of photochromic perinaphthothioindigo

Abstract

1,2-naphtho)(1,8-naphtho)thioindigo (PNT) has been synthesized following a simple Friedel-Crafts route and its photochemical properties in toluene and polymethylmethacrylate (PMMA) have been characterized. PNT is a photochromic molecule capable of reversible photoisomerization between a yellow form (cis-PNT, k max = 484 nm) and a purple form (trans-PNT, k max = 595 nm). The stable purple form converts to the yellow form with a trans-PNT to cis-PNT conversion quantum yield of 0.027 in toluene and 0.062 in PMMA. The unstable yellow form exhibits a cis-PNT to trans-PNT quantum efficiency of conversion of 0.27-0.85 in toluene and 0.17-0.68 PMMA, with highest conversion efficiency occurring in the vicinity of its k max of 484 nm. trans-PNT has a strong fluorescence quantum yield, 0.14 (toluene) and 0.16 (PMMA). For samples prepared photochemically in the cis-PNT form, slow thermal relaxation to the trans form occurs in the dark, with a half life of about 17 h in toluene (25°C) and even slower, 168 h, in PMMA. The property of photoswitching between fluorescent and non-fluorescent forms makes this material a candidate for many applications in imaging and data storage.

Synthesis and photophysical properties of a porphyrin-perinaphthothioindigo dye

“…Therefore, usual photochromic compounds such as azobenzenes and diarylethenes cannot be used in this system. However, since the S 1 state of the transisomer of perinaphthothioindigo (PNT, 2.0 eV) [14,15] is lower than that of zinc porphyrin, isomerization of the PNT part is expected after two-photon excitation of the zinc porphyrin moiety [16]. In this way, at first, we designed a PNT attached-bisporphyrins 2 using an ethynylene bond as a more efficient two-photon absorbing photochromic compound as shown in Scheme 1.…”

Synthesis, Photophysical, Electrochemical, and Halochromic Properties of peri-Naphthoindigo

“…On the contrary, analogous compounds with the H-chromophore installed between two ortho -substituted benzene rings, namely indigoids, have extensively been studied in the literature. For example, indigo and analogous compounds have been used as vat dye, food colorants, pigments for contact lenses, ambipolar organic semiconductors, and ligands for various metal complexes. , Thioindigo, peri -naphthothioindigo, N,N′-disubstituted indigos, and hemiindigos are known to show photochromic behavior . Hemithioindigos are promising tools in the competitive field of molecular machines …”