4,5hyphen;Iminophenanthrene (4Hhyphen;benzodefcarbazole, C14H9N) crystallizes in space groupI41cdof the tetragonal system with cell dimensions ofathinsp;equals;thinsp;bthinsp;equals;thinsp;7.428lpar;5rpar;andcthinsp;equals;thinsp;35.58lpar;3rpar; Aring;. The molecular packing is reported. Tetragonal crystals can undergo a sluggish transformation to a triclinic form with cell dimensions ofathinsp;equals;thinsp;12.70lpar;4rpar;, bthinsp;equals;thinsp;12.96lpar;3rpar;, cthinsp;equals;thinsp;11.88lpar;3rpar; Aring;, agr;thinsp;equals;thinsp;90.0lpar;1rpar;, bgr;thinsp;equals;thinsp;99.0lpar;1rpar;, ggr;thinsp;equals;thinsp;98.3lpar;1rpar;deg;. The new form exhibits a redhyphen;shifted, broad, structureless fluorescence spectrum characteristic of excimer emission. Tetragonal form and monomerlike fluorescence are recovered at a wellhyphen;defined transition at 73deg;C. Delayed fluorescence due to tripletndash;triplet exciton annihilation has been observed in both forms of the material.
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