Gated Photochromism and Acidity Photomodulation of a Diacid Dithienylethene Dye

Five diarylethene photochromic derivatives, the structures of which incorporate a central benzothiophene unit, a left-hand thiazole group, and a right-hand benzothiophene group, have been prepared. The compound with a thiazole unit with no substituent on the reaction-center carbon atom reveals an unprecedented transformation upon light irradiation. When the 4-position of thiazole is protected by a methyl group, the compounds show high photosensitivity and photochromic properties. In this case, light irradiation affords new compounds with [5]helicene structures featuring the highest redshifted absorption maxima reported to date.

Section: Resultsmentioning

confidence: 99%

Substituent Effects on the Photochromic Properties of Benzothiophene‐Based Derivatives

Galangau

Nakashima

Maurel

et al. 2015

“…In the present paper, we scrutinize the oxidation behavior of the simple dithienylethene dye DTE(COOH) 2 , which can exist either in its open (DTEO) or closed (DTEC) isomers (Scheme ). Because of its carboxylic groups, this molecule exhibits a rich behavior in terms of acid–base gated photochromism and photomodulation 8. UV‐light irradiation of a solution of the open isomer triggers a photocyclization reaction and generates the closed isomer.…”

Section: Introductionmentioning

confidence: 99%

Proton Catalysis in the Redox Responsivity of a Mini‐Sized Photochromic Diarylethene

Massaad

Micheau

Coudret

et al. 2013

Self Cite

A thermally irreversible dithienylethene (DTE) photochrom can be turned into a thermally reversible one in presence of Cu(II) triflate. A ring opening (DTEC closed→DTEO open) occurs through the formation of a copper-containing fast transient intermediate. Stopped-flow experiments monitored at 410 and 780 nm have allowed to show that the stoichiometry of this intermediate is DTE/Cu=1:1. At longer monitoring times (i.e., several seconds after mixing), the intermediate undergoes a slow decay while the residual DTEC closed form opens. A joint detailed kinetic and electrochemical analysis has unveiled a proton catalysis scenario in which electron transfer between DTEC and Cu(II), ligand exchange, protonation-deprotonation equilibria of the cation radicals and ring opening are embedded into two main reaction cycles. At the beginning of the reaction, Cu(II) is reduced into Cu(I) and DTE is degraded without ring opening. Then, as the reaction progresses, the triflic acid released from the Cu(II) reduction switches-on a propagation cycle during which ring opens without any more Cu(II) consumption. Cyclic voltammetry, spectro-electrochemical measurements, delayed photocoloration experiments in presence of Cu(II) and acid-base additions have confirmed the main features of the proton catalysis.

“…Only the thienyl protons and the methyl groups showed a slight linear chemical shift of about 0.1 ppm upon lowering the temperature from 300 to 230 K,27 whereas the other chemical shifts remained unchanged within the experimental errors (<0.05 ppm). A non‐linear shifting of the proton signals, which could be used to estimate the Δ G ≠ values of the parallel versus anti‐parallel equilibrium30, 31 could not be observed in the VT measurements of compound 1 o .…”

Section: Resultsmentioning

confidence: 99%

Exploring the Conformational Space of Bridge‐Substituted Dithienylcyclopentenes

Fredersdorf

Göstl

Kolmer

et al. 2015

Fredersdorf, M.; Göstl, R.; Kolmer, A.; Schmidts, V.; Monecke, P.; Hecht, S.; Thiele, C.M. Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Fredersdorf, M., Göstl, R., Kolmer, A., Schmidts, V., Monecke, P., Hecht, S., & Thiele, C. M. (2015). Exploring the conformational space of bridge-substituted dithienylcyclopentenes. Chemistry -A European Journal, 21(41), 14545-14554. DOI: 10.1002/chem.201501842 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. [a, b] Robert Gçstl, [c, d] Andreas Kolmer, [a] VolkerS chmidts, [a] Peter Monecke, [b] StefanH echt,* [c] and ChristinaM.T hiele* [a] Abstract: Stimuli responsive compounds and materials are of high interesti ns ynthetic chemistry and materials science, with light being the most intriguing stimulus due to the possibility to remote control the physicochemical properties of am olecule or am aterial. There is ac onstant quest to design photoswitches with improveds witchinge fficiency and especially diarylethene-type switches promise photo cyclization quantum yields up to unity.H owever,o nly limited attention has been paid towards the influence of the solution conformationo nt he switchinge fficiency.H ere, we describe ad etailed NMR spectroscopic investigation on the conformational distribution of bridge-substituted dithienylcyclopentenes in solution.W ec ould discriminate between several photoactive and photoinactive as well as two diastereomorphous conformationsa nd show that the trends observed in the switching efficiencym atch the conformer populations obtainedf rom state of the a...