Photochromism of Dithienylethenes Containing Fluorinated Thiophene Rings

Abstract

Keywords: Density functional calculations / Diarylethenes / Fluorine / Photochromism / UV/Vis spectroscopy Bis(3-thienyl)perfluorocyclopentenes containing partially fluorinated thiophene rings were synthesized and their behaviors examined. Dithienylethenes containing chlorinated thiophene rings were also prepared as reference compounds. The absorption maxima of the closed-ring isomers, their thermal stabilities, and their quantum yields varied depending on the substitution position. The absorption maxima showed a red shift upon fluorine substitution at the 2-or 4-positions of the thiophene ring, whereas a blue shift was observed upon substitution at the 5-position. This shift was explained by the shape of the HOMO and LUMO and was well repro-

Highly reactive bis-cyclooctyne-modified diarylethene for SPAAC-mediated cross-linking

“…The cycloheptanone 6 was brominated, and the obtained bromo-derivative 16 was converted (through alkene 17) into the cyclooctanone 18, similarly to the transformation of 6 to 10 described above. The carbonyl group in 18 was protected to allow synthesizing the DAE derivative 20 using the procedure reported previously by Irie et al 18 Then the carbonyl groups were liberated (forming compound 21). Formation of the enol triflate (compound 22) followed by the HOTf elimination completed the synthesis of the DAE building block 5 in about 10% overall yield, calculating on 6.…”

Discovery of New Fluorescent Dyes: Targeted Synthesis or Combinatorial Approach?

“…After the integration of this synthetic method into a fully compatible protocol, the positions for electronic changes with various substituents were rationally predicted through the deliberation of computational studies; the R 1 position of the [90] lowest unoccupied molecular orbital (LUMO) has a significantly smaller lobe than that of the highest occupied molecular orbital (HOMO) based on our calculation; therefore, we postulated that introduction of EDG at the R 1 position could trigger a bathochromic shift in our core skeleton [93]. The predicted positions (R 1 and R 2 ) were systematically modified with various substituents by the combination of five different aldehydes with five different pyridines having various electronic properties.…”

Effects of the Peripheral Heteroaryl Substituents on the Photochromism of New Pyridine-Containing Diarylethenes

“…To date, the design and synthesis of diarylethene derivatives have mainly focused on the variation of two heteroaryl moieties, which stimulated character diversity of this class of molecules. 1 For example, diarylethenes having two thiophene moieties exhibit outstanding thermal stability and outstanding fatigue resistance; 1,8 whereas symmetrical diarylethenes having two pyrrole groups are thermally unstable and return to the open-ring isomers even in the dark. 9 In the case of six-membered heteroaryl rings, diarylethenes having two phenyl/naphthyl groups are thermally reversible with poor photochromism, 10,11 but some unsymmetrical diarylethenes having a six-membered heteroaryl ring are thermally irreversible with good photochromism.…”