Thiazolothiazole‐Based Fluorescence Probe towards Detection of Copper and Iron Ions through Formation of Radical Cations

Abstract

This work describes the design and synthesis of fluorescent triphenylamine‐thiazolothiazole based donor‐acceptor‐donor chemosensor 4,4′‐(thiazolo[5,4‐d]thiazole‐2,5‐diyl)bis(N,N‐bis(4‐methoxyphenyl)aniline) (TTz‐1). TTz‐1 exhibited positive solvatochromism effect in the excited state due to its strong intramolecular charge transfer (ICT) properties. Potential application of TTz‐1 toward metal ion detection were explored systematically. It was established that the addition of Cu(ClO4)2 . 6H2O into TTz‐1 resulted in near‐infrared (NIR) colorimetric and fluorescent quenching allowing for Cu2+ detection. EPR studies indicate that formation of radical cation occurs when Cu2+ and TTz‐1 interact. TTz‐1 was also able to detect Fe3+ employing a color change from orange to colourless (fluorescent). It was observed that the TTz‐1 emission peak at 567 nm was quenched after addition of Cu2+ and Fe3+ metal ions. Electrochemical analysis showed that LUMO values of the TTz‐1 decreased after addition of Fe3+ and Cu2+. The limits of detection (LOD) for Cu2+ and Fe3+ detection by TTz‐1 were found to be 0.30 μM and 0.29 μM, respectively. These results suggest that the TTz‐1 is a highly selective and sensitive sensor for the detection of Cu2+ or Fe3+ ions.

Modulation of the Naked‐Eye and Fluorescence Color of a Protonated Boron‐Doped Thiazolothiazole by Anion‐Dependent Hydrogen Bonding

“…[14][15][16] Furthermore, TzTz push-pull compounds and viologens display strong solvatochromism and electrochromism covering a large fluorescence spectral range. [17][18][19] In the area of chemosensing, TzTz-based fluorophores have been used to detect various metal cations, including Hg 2 + , [20] Cu 2 + , [18,21] Cr 3 + and Al 3 + , [22] Cr 2 O 7 2À and MnO 4 À anions, [23] as well as glucose. [24] The mode of detection in these sensing applications varies, ranging from fluorescence quenching through coordination, [20] non-coordinative electron transfer [23] or radical cation formation, [18] to fluorescence enhancement.…”

Triphenylamine Derived Radical Cations for Colorimetric Cu2+ Sensors and as an Antibacterial Agent

“…Compared to other methods of amine radical cation generation including anodic oxidation, photoionization, and photoinduced electron transfer, where the amine radical cations are generated as transient intermediates, this approach allows for the generation of stable organic radical cations with distinct color changes in a very simple operation [10] . Thus, a series of colorimetric Cu 2+ sensors have been reported on the basis of generating the corresponding organic radical cations via the redox couple Cu 2+ /Cu + in N‐containing π‐systems [11–14] . However, the recognition of Cu 2+ using this approach in aqueous media is somewhat limited.…”

“…[10] Thus, a series of colorimetric Cu 2 + sensors have been reported on the basis of generating the corresponding organic radical cations via the redox couple Cu 2 + /Cu + in Ncontaining π-systems. [11][12][13][14] However, the recognition of Cu 2 + using this approach in aqueous media is somewhat limited.…”

Donor‐Acceptor Based 1,8‐Naphthalimide Substituted Phenothiazines: Tuning of HOMO‐LUMO Gap

“…The incorporation of heteroatom‐based moieties such as phenothiazine, thiazole, benzothiazole, benzothiadiazole etc . in donor‐acceptor (D‐A) chromophores have received substantial attention in the field of nonlinear optics (NLO), organic light‐emitting diodes (OLEDs), organic photovoltaics (OPVs), etc [6–9] . In order to fine tune the HOMO/LUMO energy levels, D‐A based chromophores can be utilized by; (a) changing the donor or acceptor strength or (b) incorporation of different π‐linkers [10–17] .…”

“…in donor-acceptor (D-A) chromophores have received substantial attention in the field of nonlinear optics (NLO), organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), etc. [6][7][8][9] In order to fine tune the HOMO/ LUMO energy levels, D-A based chromophores can be utilized by; (a) changing the donor or acceptor strength or (b) incorporation of different π-linkers. [10][11][12][13][14][15][16][17] Therefore, our group is interested to design and synthesize push-pull based chromophores by modulating the donor and acceptor moieties for the application in optoelectronics.…”