Novel photoresponsive cyclicparaphenylenediazenes: structure, strain energy, - isomerization, and electronic properties

• Published in: Photochemical & photobiological sciences 2019-05, Vol.18 (5), p.1185-1196
• Main Authors: Akbar Ali, Mohamad, Alam, Mohammad Abrar
• Format: Article
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c8pp00502h

A series of cis - trans isomers of cyclicparaphenylenediazenes (CPPDs) have been designed to explore their potential applications in solar thermal fuels and photoswitchable devices. In this work, three isomers of cis - trans -[3]CPPD, seven isomers of cis - trans -[4]CPPD, eleven isomers of cis - trans -[5]CPPD, and sixteen isomers of cis - trans -[6]CPPD have been proposed using density functional theory (DFT) at the B3LYP/6-31+G(d,p) level of theory. The stability of these CPPDs has been quantified by the homodesmotic reaction approach. Strain energies (SE) indicate that 3-cct, 4-ctct- anti , 5-cctct- anti , and 6-cttttc- anti are stable molecules in their respective CPPDs. The SE and heats of formation of cis - trans -CPPDs were also compared with those of all- cis -CPPDs and all- trans -CPPD isomers. The calculations suggest that cis - trans -CPPDs are more stable than all- cis and all- trans -CPPDs. The SE and also suggest that 3-cct, 4-ctct- anti , 5-cctct- anti , and 6-cttttc- anti are important candidates for laboratory test. The calculated highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) energy gaps of cis - trans -CPPDs indicate that these oligomers are potential materials for the construction of solar cells. Time-dependent (TD) DFT calculations of CPPDs show a characteristic peak in the range of 450 nm to 600 nm, which is consistent with previous studies. The predicted structures, and thermochemical and electronic properties can be a good starting point for the synthesis of CPPD-based photoswitchable and solar fuel cell devices. Novel structures and related properties of cyclicparaphenylenediazenes.