Photoswitching of dipole moments, charge-transfer and spectroscopic properties

✍ Scribed by F. Dietz; G. Olbrich; S. Karabunarliev; N. Tyutyulkov

• Book ID: 104108526
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 252 KB
• Volume: 379
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/s0009-2614(03)01314-9

✦ Synopsis

The photoswitching of the dipole moment, absorption spectra and oxidation/reduction potentials of donor-acceptor-substituted dihydropyrene-[2,2]metacyclophanediene photochromic systems has been studied theoretically. Two types of basic structures can be formulated for the closed-ring dihydropyrene photoisomers: a conjugated betaine dye type and a merocyanine type structure, respectively. The thermodynamically less stable [2,2]metacyclophanediene forms have significantly larger dipole moments (>40 D) and longer wavelength absorption (CT transition in NIR region) in relation to the closed-ring dihydropyrene structures (<20 D and absorption in visible region). The reason for the strong changing of these properties is that the [2,2]metacyclophanediene fragment acts as a p-electron conjugation barrier which gives rise to a charge separation of the donor and acceptor substituents, respectively.