Fluorescent Dyes with Large Stokes Shifts Based on Benzo[1,2‐d:4,5‐d']bis([1,3]dithiole) (“S⁴‐DBD Dyes”)

Abstract

We report on a further development of [1,3]‐dioxolo[4.5‐f]benzodioxole (DBD) fluorescent dyes by replacement of the four oxygen atoms of the heterocyclic core by sulfur atoms. This variation causes striking changes of the photophysical properties. Whereas absorption and emission significantly shifted to longer wavelength, the fluorescence lifetimes and quantum yields are diminished compared to DBD dyes. The latter effect is presumably caused by an enhanced intersystem crossing to the triplet state due to the sulfur atoms. The very large Stokes shifts of the S4‐DBD dyes ranging from 3000 cm–1 to 7400 cm–1 (67 nm to 191 nm) should be especially emphasized. By analogy with DBD dyes a broad variation of absorption and emission wavelength is possible by introducing different electron withdrawing substituents. Moreover, some derivatives for coupling with biomolecules were developed.

Synthesis and Spectrophotometric Studies of 9‐Substituted‐4,5‐dimethoxyacridine Multifunctionalizable Fluorescent Dyes and Their Macrocyclic Derivatives

“…A study on 4,5‐dimethoxyacridone ( 12 ) indicated that methoxy groups reduced quantum yield compared to the unsubstituted acridone ( 2 ) (0.410→0.100). All of the fluorescent compounds showed extremely large Stokes ‐shifts compared to the reported dyes [46–54] . This advantageous photophysical property can reduce interferences from self‐absorption and auto‐fluorescence, thus provides outstanding sensitivity and resolution for optochemical devices.…”

“…All of the fluorescent compounds showed extremely large Stokes-shifts compared to the reported dyes. [46][47][48][49][50][51][52][53][54] This advantageous photophysical property can reduce interferences from self-absorption and autofluorescence, thus provides outstanding sensitivity and resolution for optochemical devices. Compounds with large Stokesshifts, especially functionalizable-group-containing derivatives, which are reported herein, can have great importance for practical applications and are in the focus of very recent research activities.…”

“…Compounds with large Stokesshifts, especially functionalizable-group-containing derivatives, which are reported herein, can have great importance for practical applications and are in the focus of very recent research activities. [46][47][48][49][50][51][52][53][54] Although studies on photophysical behavior of the new fluorescent precursors were carried out primarily from the aspect of the nature of the substituent at position 9 of acridine, it should be noted that fluorescence properties of acridine dyes strongly depend on the polarity of the medium as well as on the hydrogen-bonding ability of the solvent (they generally have weak fluorescence in apolar solvents and strong fluorescence in protic solvents). [45,55,56] Moreover, the protonated forms of these weak bases usually have spectral features quite different than those of the corresponding neutral forms.…”

Sulfur Tuning of [1,3]‐Dioxolo[4.5‐f]benzodioxole (DBD) Fluorescent Dyes

“…This causes a significant lowering of the fluorescence quantum yields and lifetimes [7b] . Moreover, the quite efficient synthesis of S 4 ‐DBD dyes mandatorily requires the use of extremely malodorous tert ‐butylthiol [7a] . It should be noted that very recently an alternative route has been published [7d] .…”

Improved, Odorless Access to Benzo[1,2-d;4,5-d′]- bis[1,3]dithioles and Tert-butyl Arylsulfides via C-S Cross Coupling

“…Benzo[1,2-d;4,5-d′]bis[1,3]dithioles 1 ( Figure 1 ) have emerged as important building blocks for a range of functional materials. For example benzo[1,2-d:4,5-d′]bis[1,3]dithiole-based fluorescent dyes (“S4 DBD dyes” 2 ) exhibit large stokes shifts making them promising candidates for super-resolution microscopy such as stimulated emission depletion (STED) microscopy [ 1 , 2 ]. Moreover, conjugated polymers 3 consisting of such building blocks show fluorescence response upon oxidation rendering these materials interesting for oxidant sensing [ 3 ].…”