TY  - JOUR
A1  - Haubitz, Toni
A1  - John, Leonard
A1  - Freyse, Daniel
A1  - Wessig, Pablo
A1  - Kumke, Michael Uwe
T1  - Investigating the Sulfur "Twist" on the Photophysics of DBD Dyes
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - The so-called DBD ([1,3]dioxolo[4,5-f][1,3]benzodioxole) dyes are a new class of fluorescent dyes, with tunable photophysical properties like absorption, fluorescence lifetime, and Stokes shift. With the development of sulfur based DBDs, this dye class is extended even further for possible applications in spectroscopy and microscopy. In this paper we are investigating the basic photophysical properties and their implications for future applications for S-4-DBD as well as O-4-DBD. On the basis of time-resolved laser fluorescence spectroscopy, transient absorption spectroscopy, and UV/vis-spectroscopy, we determined the rate constants of the radiative and nonradiative deactivation processes as well as the energy of respective electronic states involved in the electronic deactivation of S-4-DBD and of O-4-DBD. For S-4-DBD we unraveled the triplet formation with intersystem crossing quantum yields of up to 80%. By TD-DFT calculations we estimated a triplet energy of around 13500-14700 cm(-1) depending on the DBD dye and solvent. Through solvent dependent measurements, we found quadrupole moments in the range of 2 B.
Y1  - 2020
U6  - https://doi.org/10.1021/acs.jpca.0c01880
SN  - 1089-5639
SN  - 1520-5215
VL  - 124
IS  - 22
SP  - 4345
EP  - 4353
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Freyse, Daniel
A1  - Schuster, David
A1  - Kelling, Alexandra
T1  - Fluorescent dyes with large stokes shifts based on Benzo[1,2-d:4,5-d']bis([1,3]dithiole) (“S4-DBD Dyes”)
JF  - Europan journal of organic chemistry
N2  - 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 S-4-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.
KW  - fluorescent dyes
KW  - sulfur
KW  - heterocycles
KW  - stokes shift
KW  - photophysics
Y1  - 2020
U6  - https://doi.org/10.1002/ejoc.202000093
SN  - 1434-193X
SN  - 1099-0690
VL  - 2020
IS  - 11
SP  - 1732
EP  - 1744
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wessig, Pablo
A1  - Gerngross, Maik
A1  - Freyse, Daniel
A1  - Bruhn, P.
A1  - Przezdziak, Marc
A1  - Schilde, Uwe
A1  - Kelling, Alexandra
T1  - Molecular Rods Based on Oligo-spiro-thioketals
JF  - The journal of organic chemistry
N2  - We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.joc.5b02670
SN  - 0022-3263
VL  - 81
SP  - 1125
EP  - 1136
PB  - American Chemical Society
CY  - Washington
ER  -