Abstract
Quinacridone diimines 1–10 were synthesized by the condensation of anilines with alkyl substituted quinacridones (QA). Photophysical and electrochemical properties of the compounds were investigated. Unconventional behavior of absorption spectra suggested a decrease in π_conjugation within the QA skeleton as well as lack of extended π_conjugation between the QA skeleton and the N-phenyl rings. A computational study of compounds 1–10, a variable temperature 1H NMR study of compounds 2, 7 and 10 (for instance), and single crystal X-ray analysis of 2, 3, 6, 7, 8 and 10 indicated that the anomalous behavior is due to the buckled, non-planar structure of the quinacridones. Moreover the molecules existed in two interconvertible geometric isomeric forms at different temperatures. Molecular orbital calculations were performed at B3LYP/6-31+G(d), B3PW91/6-31G(d) and PBEPBE/6-31G(d) levels of theory at B3PW91/6-31G(d) optimized structures for both isomers of all compounds (1–10); the results obtained are in close agreement with the experimentally determined values.
Highlights
IntroductionJones and co-workers have reported the crystal structure of QA.[7]. Schmidt and co-workers have reported different polymorphic forms of QA that differ significantly in terms of their coloristic properties.[8]
Abbottabad, KPK, Pakistan 22060 f Centre of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O
On the basis of single crystal X-ray analysis, molecular modeling calculations and the variable temperature 1H NMR spectrum study, we report that these QA diimines exist in different geometrical isomeric forms at different temperatures with the buckled QA skeleton in a non-planar fashion
Summary
Jones and co-workers have reported the crystal structure of QA.[7]. Schmidt and co-workers have reported different polymorphic forms of QA that differ significantly in terms of their coloristic properties.[8]. A careful understanding of the relationship between molecular structures, conformations and optical and electronic properties in solution and condensed states will lead to the development of new strategies for the preparation of high-performance organic optical and electronic materials. For in-depth structural exploration of these compounds, single crystals have been grown at different temperatures for 752 | New J. On the basis of single crystal X-ray analysis, molecular modeling calculations and the variable temperature 1H NMR spectrum study, we report that these QA diimines exist in different geometrical isomeric forms at different temperatures with the buckled QA skeleton in a non-planar fashion.
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