@article{TurkinHolzapfelAgarwaletal.2021,
  author    = {Turkin, Arthur and Holzapfel, Marco and Agarwal, Mohit and Fischermeier, David and Mitric, Roland and Schweins, Ralf and Gr{\"o}hns, Franziska and Lambert, Christoph},
  title     = {Solvent Induced Helix Folding of Defined Indolenine Squaraine Oligomers},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {32},
  doi       = {10.1002/chem.202101063},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256869},
  pages     = {8380-8389},
  year      = {2021},
  abstract  = {A protecting group strategy was employed to synthesise a series of indolenine squaraine dye oligomers up to the nonamer. The longer oligomers show a distinct solvent dependence of the absorption spectra, that is, either a strong blue shift or a strong red shift of the lowest energy bands in the near infrared spectral region. This behaviour is explained by exciton coupling theory as being due to H- or J-type coupling of transition moments. The H-type coupling is a consequence of a helix folding in solvents with a small Hansen dispersity index. DOSY NMR, small angle neutron scattering (SANS), quantum chemical and force field calculations agree upon a helix structure with an unusually large pitch and open voids that are filled with solvent molecules, thereby forming a kind of clathrate. The thermodynamic parameters of the folding process were determined by temperature dependent optical absorption spectra.},
  language  = {en}
}
@article{KarGehrigAllampallyetal.2016,
  author    = {Kar, Haridas and Gehrig, Dominik W. and Allampally, Naveen Kumar and Fern{\´a}ndez, Gustavo and Laquai, Fr{\´e}d{\´e}ric and Ghosh, Suhrit},
  title     = {Cooperative supramolecular polymerization of an amine-substituted naphthalene-diimide and its impact on excited state photophysical properties},
  series = {Chemical Science},
  volume    = {7},
  journal   = {Chemical Science},
  number    = {2},
  doi       = {10.1039/c5sc03462k},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191459},
  pages     = {1115-1120},
  year      = {2016},
  abstract  = {A donor-acceptor-donor (D-A-D) type naphthalene-diimide (NDI-H) chromophore exhibits highly cooperative J-aggregation leading to nanotubular self-assembly and gelation in n-decane, as demonstrated by UV/Vis, FT-IR, photoluminescence and microscopy studies. Analysis of temperature-dependent UV/Vis spectra using the nucleation-elongation model and FT-IR data reveals the molecular origin of the cooperative nature of the self-assembly. The supramolecular polymerization is initiated by H-bonding up to a degree of polymerization similar to 20-25, which in a subsequent elongation step promotes J-aggregation in orthogonal direction leading to possibly a sheet-like structure that eventually produces nanotubes. Time-resolved fluorescence and absorption measurements demonstrate that such a tubular assembly enables very effective delocalization of excited states resulting in a remarkably prolonged excited state lifetime.},
  language  = {en}
}
@article{GraebGeidel2019,
  author    = {Gr{\"a}b, Patrick and Geidel, Ekkehard},
  title     = {Spectroscopic studies of food colorings},
  series = {World Journal of Chemical Education},
  volume    = {7},
  journal   = {World Journal of Chemical Education},
  number    = {2},
  doi       = {10.12691/wjce-7-2-13},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201908},
  pages     = {136-144},
  year      = {2019},
  abstract  = {In chemical education, it is often a challenge to understand the basic principles of spectroscopic techniques due to missing connections to the real world. Therefore, the present contribution offers context-based applications of UV/Vis spectroscopy for analytics of food colorings with which learners can improve their skills regarding this method. The spectroscopic determination of food colorings seems to be a promising approach due to the long tradition and omnipresence of dyes in supermarket products. The therefor-required spectral data for commonly used dyes are provided for educational usage. Qualitative and quantitative analytics of food colorings in four different lemonades and chocolate beans have been used to introduce learners to important analytical techniques like sample preparation or elimination of confounding factors. These analytics also display the limitations of the method in the visible range of light in the case of tartrazine and curcumin. By applying Lambert-Beer-Bouguer's Law in different variations, typical calculations of concentrations can be studied in quantitative analyses. The studied food samples demonstrate the different usage of food colorings depending on the country of sale. Finally, a 3D-printable low-cost photometer suitable for the discussed quantitative analytics in educational contexts is presented.},
  language  = {en}
}
@article{SchairerWagnerGeidel2018,
  author    = {Schairer, Patrick and Wagner, Stephan and Geidel, Ekkehard},
  title     = {An experimental introduction to basic principles of the interaction of electromagnetic radiation with matter},
  series = {World Journal of Chemical Education},
  volume    = {6},
  journal   = {World Journal of Chemical Education},
  number    = {1},
  doi       = {10.12691/wjce-6-1-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175811},
  pages     = {29-35},
  year      = {2018},
  abstract  = {To understand basic principles about the interaction of electromagnetic radiation with matter is often a challenge in chemical education due to the difficult theoretical background of this topic. The present contribution therefore offers an experimental based introduction into the basic principles of UV/Vis spectroscopy following a three-step strategy. The starting point is to construct a simple self-built spectrometer working within the visible range of light. Learners can explore the most important components of such a device and understand their functions without previous knowledge. In a second step, emission spectra of different common light sources are investigated and compared. Finally, spectroscopic experiments are suggested for chemical education such as the qualitative detection of cations and the quantitative analysis of the dye carmine in food. This context-based introduction links chemical applications with the everyday life. It can be presumed that this way, learners are provided an easier access to radiation-matter interaction.},
  language  = {en}
}