Towards thermally stable cyclophanediene-dihydropyrene photoswitches

• Published in: Journal of molecular modeling Vol. 21; no. 6; p. 148
• Main Authors: Khan, Nasir, Sheikh, Nadeem S., Khan, Ather F., Ludwig, Ralf, Mahmood, Tariq, Rehman, Wajid, Al-Faiyz, Yasair S. S., Ayub, Khurshid
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2015
• Subjects: Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Models, Chemical; Models, Molecular; Molecular Medicine; Original Paper; Photochemistry; Stereoisomerism; Theoretical and Computational Chemistry; Thermodynamics; Electrocyclization; Photoswitches; Rational design; Sigmatropic rearrangement; Thermal process; DFT calculations
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-015-2695-0

Cyclophanediene dihydropyrenes (CPD-DHP) are photochromic compounds because they change their color by irradiation with lights of different color. Potential use of CPD-DHP photoswitch in memory devices requires a very slow thermal return in the dark in the absence of any side reaction. Herein, thermal return of CPDs to DHPs, and an unwanted sigmatropic shift in DHP is studied through density functional theory calculations at (U)B3LYP/6-31+G(d). The thermal return occurs through symmetry forbidden conrotatory electrocyclic reaction. Dimethyl amino CPD-DHP photoswitch pair has the highest activation barrier for electrocyclization and sigmatropic shifts. The lowest activation barrier for symmetry forbidden electrocyclization is observed for GeBr 3 functionalized CPD. An unprecedented decomposition pathway involving elimination of the internal substituents is predicted for Cl, Br and SMe functionalized DHPs. This study shows great promise in understanding the Woodward Hoffmann forbidden processes and, in reducing the synthetic efforts toward robust photochromes for memory applications.