Phenoxynaphthacene

A number of photochromic phenoxynaphthacenequinones were obtained using the initially synthesized 6-substituted ll-phenoxynaphthacene-5,12-quinones (IIIA) (Scheme 4).46 6,11-Dichloro-naphthacenequinone was the initial compound for the synthesis of these 6-chloro-ll-phenoxynaphthacenequinone compounds. 6-Chloro-1 l-tosylaminonaphthacene-5,12-quinone was obtained by interaction with phenox-ide potassium in DMSO and /j-tolucncsulfamidc in nitrobenzene, respectively. The latter compound was hydrolyzed in sulfuric acid to form 6-chloro-l 1-aminonaphtha-cene-5,12-quinone. The treatment of 6-chloro-l l-phenoxynaphthacene-5,12-quinone and 6-chloro-l l-aminonaphtacene-5,12-quinone with potassium phenoxide gave rise to 6-tosylamino- and 6-amino-ll-phenoxynaphthacene-5,12-quinones... 

IIIA). The latter compounds were used for the synthesis of 6-acetyl- and 6-nitro-substituted ll-phenoxynaphthacene-5,12-quinone by acetylation with acetic anhydride in the presence of catalytic content of sulfuric acid and by oxidation with peroxyacetic acid, respectively. 

Acetylation of 6-methylamino-l l-phenoxynaphthacene-5,12-quinone by acetic anhydride in the presence of a catalytic quantity of sulfuric acid and 6-oxy-ll-phenoxynaphthacene-5,12-quinone in the presence of pyridine yields /V-acctyl-,6-methylamino- and 6-acetoxy-ll-phenoxynaphthacene-5,12-quinones (IIIA).46... 

Oxy-ll-phenoxynaphthacene-5,12-quinone (IIIA) was separated after the interaction of 6,12-diphenoxynaphthacene-5,ll-quinone with piperidine or secondary amines.46... 

Aryloxy-derivatives of 6-amino-11 -phenoxynaphthacene-5,12-quinones (IIIA) were synthesized by heating 6-amino-ll-chloro-5,12-naphthacenequinone in a phenol-phenoxide melt of a suitably substituted phenol or by interaction with a corresponding substituted potassium phenoxide in DMSO in the presence of cuprous (I) chloride.52... 

Unlike phenoxyanthraquinones, the photochromism of phenoxynaphthacene-quinones is characterized by a long lifetime of the photoinduced ana form. This property allows one to perform a more detailed study of the mechanism of the photochromic transformations (Scheme 20).5... 

Reversibility of the spectral changes under irradiation and the photostability of the compound without the phenoxy substituent suggested a photochromic para-ana-quinone transformation of 9-phenoxy-pyrone (9-phenoxynaphthacene [12,11 -bc]-2,8-pyrandione) (Table 7.10, Scheme 22).48... 

The absorption bands of the photoinduced ana form of phenoxynaphthacene-pyridines were shifted to the blue compared with the corresponding absorption bands of phenoxynaphthacenepyridones. This was explained by the fact that these compounds have the quinone-imine form.39... 

FIG. 7.4 (A) Use of diffusional electron relay to amplify the electrochemical stpial of the photo-switchable phenoxynaphthacene quinone/tetradecanethiol mixed monolayer. (B) Cyclic voltammograms of the electrode in the presence of BV (2) (I mM) (a) in the trans-quinone state (la) and (b) In the ono-quinone state (I b), Recorded at pH 7.5, scan rate 5 mV s. Inset Photoswitching behavior of the electrocatalytic current (Adapted from reference 43, Figure 8, scheme 5. Copyright 1996, American Chemical Society.)... 

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