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Triplet to Triplet Absorption in Organic Molecules for Use in Photochromic Devices

The photochromic behavior of hetero-aromatic molecules was studied. Particular attention has been given to the transient absorption in the polymer host poly(methyl methacrylate). Compounds studied include 1,2;5,6 dibenzacridine, dibenzo(c, g)carbazole, 6 aminochrysene and alpha-naphthoflavone. The latter two compounds show little triplet-triplet absorption, however, the former two compounds do show good absorption. The effect of varying concentration upon T-T absorption was studied and high concentrations (0.01M) seem to show lower intensities of triplet absorption than do some less concentrated samples. The degradation of the samples under exposure to sunlight and an Hg lamp are studied. The degradation due to sunlight is found to be partially reversed overnight. Dibenzo(c, g)carbazole shows far more degradation than does 1,2;5,6 dibenzacridine. Further possible uses of photochromics in military applications are considered. (Author).

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  • "The photochromic behavior of hetero-aromatic molecules was studied. Particular attention has been given to the transient absorption in the polymer host poly(methyl methacrylate). Compounds studied include 1,2;5,6 dibenzacridine, dibenzo(c, g)carbazole, 6 aminochrysene and alpha-naphthoflavone. The latter two compounds show little triplet-triplet absorption, however, the former two compounds do show good absorption. The effect of varying concentration upon T-T absorption was studied and high concentrations (0.01M) seem to show lower intensities of triplet absorption than do some less concentrated samples. The degradation of the samples under exposure to sunlight and an Hg lamp are studied. The degradation due to sunlight is found to be partially reversed overnight. Dibenzo(c, g)carbazole shows far more degradation than does 1,2;5,6 dibenzacridine. Further possible uses of photochromics in military applications are considered. (Author)."@en
  • "The report describes a continuing program of research whose aim is to investigate and evaluate new classes of triplet state photochromic materials. The work is centered upon studies of substituted aromatics and heterocyclic compounds. The effect of solvent composition upon fluorescence, phosphorescence and T-T absorption has been investigated for several compounds with the aim of determining the conditions for which the photochromic behavior of a compound will be maximized. Studies have been made for benzquinolines, dibenzacridines, 6 amino chrysene (I) and dibenzo(c, g)carbazole (II). Results of these studies are presented and discussed in terms of the solvent influence upon the lone pair of electrons on the nitrogen in aza-aromatics and for (I) and (II) in terms of a change in excited state properties compared to the ground state. The photochromic properties of several new compounds, including phenanthrolines and some oxygen containing hetercyclics; have been investigated. Results reveal one compound, 2,3 dimethyl; 1,4 phenanthroline, that shows good promise as a photochromic. Some uses of triplet state photochromics are discussed and conclusions of this work and recommendations for future studies are given. (Author)."@en
  • "The photochromic properties of several substituted aromatics and heterocyclics have been investigated. The absorption spectra, phosphorescence lifetime T-T absorption spectra and the product of triplet extinction coefficient and triplet formation efficiency, were evaluated for representative compounds. Using these data the photochromic properties of heterocyclics are compared to their hydrocarbon analogs. The values of the maximum triplet formation efficiency are lower for heterocyclics than for aromatics. However, broader T-T absorption and more efficient absorption for pumping light suggest that, on balance, heterocyclics are comparable to aromatic hydrocarbons in their effectiveness as photochromic materials. The variation of solvent induces large changes in the photochromic properties of heterocyclics thus providing a useful additional parameter for adjusting their properties. These differences also promise to shed light on the mechanism of radiationless transitions in these compounds. Recommendations for further studies to improve the photochromic properties of heterocyclics are made. (Author)."@en

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  • "Triplet to Triplet Absorption in Organic Molecules for Use in Photochromic Devices"@en
  • "Triplet to triplet absorption in organic molecules for use in photochromic devices"
  • "Triplet to triplet absorption in organic molecules for use in photochromic devices"@en

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