Synthesis and Optical Properties of Photochromic Perinaphthothioindigo
(1,2-naphtho)(1,8-naphtho)thioindigo (PNT) has been synthesized following a simple Friedel-Crafts route and its photochemical properties in toluene and PMMA characterized. PNT is a photochromic molecule capable of reversible photoisomerization between a yellow form (cis-PNT, {lambda}{sub max} = 484 nm) and a purple form (trans-PNT, {lambda}{sub 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 {lambda}{sub 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 hours in toluene (25 C) and even slower, 168 hours, 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. An anomalous excitation profile for the fluorescence from trans-PNT, showing a dip at {approx}600 nm, is an agreement with the wavelength-dependent quantum yield of conversion from trans-PNT to cis-PNT, which is highest at the absorbance peak.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15016022
- Report Number(s):
- UCRL-TR-209725; TRN: US200509%%743
- Resource Relation:
- Other Information: PBD: 10 Feb 2005
- Country of Publication:
- United States
- Language:
- English
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