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

Abstract

Dedicated to Professor Bernd Giese on the occasion of his 80th birthday. The replacement of oxygen by sulfur atoms of [1,3]-dioxolo[4.5f]benzodioxole (DBD) fluorescent dyes is an efficient way to adjust the photophysical properties (sulfur tuning). While previously developed S 4-DBD dyes exhibit considerably redshifted absorption and emission wavelength, the heavy atom effect of four sulfur atoms cause low fluorescence quantum yields and short fluorescence lifetimes. Herein, we demonstrate that the replacement of less than four sulfur atoms (S 1-DBD, 1,2-S 2-DBD, and 1,4-S 2-DBD dyes) permits a fine-tuning of the photophysical properties. In some cases, a similar influence on the wavelength without the detrimental effect on the quantum yields and lifetimes is observed. Furthermore, the synthetic accessibility of S 1-and S 2-DBD dyes is improved, compared with S 4-DBD dyes. For coupling with biomolecules a series of reactive derivatives of the new dyes were developed (azides, OSu esters, alkynes, maleimides).

Synthesis of AgI and AuI Complexes from Tetra(thiophene‐NHC)‐Substituted Ethylene and Their Tunable Fluorescence Properties

“…The wavelengths of the emission λ em for [Ag 2 L1 ](PF 6 ) 2 and [Ag 2 ( L3 ) 2 ](PF 6 ) 2 in the solid state were recorded 540 and 530 nm, respectively (see Figures S46–S47, Supporting Information). We attribute this observation to the heavy atom effect of sulfur, [ 38–41 ] the metal, [ 42,43 ] and n‐π* transitions [ 44 ] of the two lone pairs at the sulfur atom.…”

“…[36,37] As shown in Figure 3a -S47, Supporting Information). We attribute this observation to the heavy atom effect of sulfur, [38][39][40][41] the metal, [42,43] and n-π* transitions [44] of the two lone pairs at the sulfur atom.…”

[1,3]-Dioxolo[4,5-f]benzodioxole (DBD) Fluorescent Dyes; Synthesis, Properties, and Applications

“…30 The reductive cleavage of 40 gives the dithiol 41 and subsequent reaction with acetone gives the 1,2-S 2 -DBD basic building block 42 . 31 The installation of different EWGs smoothly succeeds after lithiation with n -BuLi/TMEDA/ n -hexane giving compounds 43a – c with moderate to good yields. Nonetheless, in all cases the monosubstituted products with only one EWG were obtained as byproducts.…”

“…The secondary alcohol 55 was prepared in three steps from 49 and was further used for the synthesis of several S 1 -DBD dyes with reactivity towards biomolecules (Scheme 8). 31 Scheme 8 Synthesis of S 1 -DBD dyes. Reagents and conditions: (i) thiourea/HOAc, 82%.…”

5,6-Dimethylbenzo[d][1,3]oxatellurole

“…In contrast, [1,3] Groom et al, 2016) for [1,3]oxaselenoles and [1,3]oxathioles indicates a paucity of such structures as well. One [1,3]oxaselenole (Laitalainen et al, 1983) and thirteen sulfur congeners are known, such as the structurally similar 6,6-dimethyl-[1,3]dioxolo[4 0 ,5 0 :4,5]benzo [1,2-d][1,3]oxathiole-8-carbaldehyde (Wessig et al, 2021). Reported derivatives of selenafulvalene and tetratellurafulvalene (Kojima et al, 2004;Carroll et al, 1982) bear only limited structural resemblance to the title compound, since these molecules are almost planar due to the absence of an sp 3 -hybridized carbon atom in the heteroaromatic ring.…”