A conjugated photoresponsive dithienylethene–ferrocene system: applications in secret writing and decoding information. Issue 22 (30th May 2022)

• Record Type: Journal Article
• Authors: Karmakar, Manisha; Bag, Sayan Kumar; Mondal, Bijan; Thakur, Arunabha
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 22(2022)
• Page Start: 8860
• Page End: 8873
• Publication Date: 2022-05-30
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc00738j
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A ferrocene appended dithienylethene (DTE-Fc) bridged π-conjugated photochromic material that can be applicable in a lithographic technique (erasable ink) and deciphering secret codes. Abstract : Although photoswitchable or photoactivatable fluorescent diarylethenes are extensively applied in various fields such as optical memory, optical transistors, bioimaging, and super-resolution imaging, they encounter drawbacks of fluorescence quenching in the aggregated/solid state. Therefore, the design and synthesis of solid state "turn-on" fluorescent photochromic materials remain a great challenge. Here, in this work, a ferrocene appended dithienylethene (DTE-Fc) bridged π-conjugated photochromic material, 4o/4c, with high photoreaction quantum yields ( Φ o→c = 0.83 and Φ c→o = 0.021) and fatigue resistance properties, was rationally designed. The conversion of pale violet, 4o, to green color, 4c, is associated with a slightly higher rate constant ( k solution = 0.007 s −1 and k solid = 0.005 s −1 ) than the conversion of 4c to 4o ( k solution = 0.004 s −1 and k solid = 0.003 s −1 ) both in solution and in the solid state indicating that photocyclization occurs at a higher rate than cycloreversion. It is a unique example of a "turn-on" mode fluorescent ( Φ F = 0.299) DAE without a traditionally known fluorophore or a S, S -dioxide moiety, in solution and in the solid state. The "turn-on" mode fluorescence behaviour was further validated by the time-resolved fluorescence spectroscopic measurement and quantum chemical calculations (DFT). Furthermore, this DTE-Fc derivative, 4o/4c, is found to be highly efficient in a lithographic technique (erasable ink) and deciphering secret codes (QR/bar code), opening real opportunities for practical applications in anti-counterfeiting.