Highly Luminescent TCNQ in Melamine
- Author(s)
- Vipin Mishra, Arthur Mantel, Peter Kapusta, Alexander Prado-Roller, Hidetsugu Shiozawa
- Abstract
Optical properties of molecules change drastically as results of interactions with surrounding environments as observed in solutions, clusters and aggrergates. Here we make 7,7,8,8-tetracyanoquinodimethane (TCNQ) highly luminescent by encapsulating it in crystalline melamine. Coloured single crystals are synthesized by slow evaporation of a solution of melamine and TCNQ in water and tetrahydrofuran. Single crystal X-ray diffraction reveals the lattice structure of pure melamine, meaning that the colour is of impurities. Both mass spectrometry and UV-Vis spectroscopy combined with density-functional theory calculations elucidate that the impurity species are neutral TCNQ and its oxidation product, dicyano-$p$-toluoyl cyanide anion (DCTC$^-$), whose concentrations in a melamine crystal can be controlled by adjusting the molar ratio between melamine and TCNQ in the precursor solution. Fluorescence exciation-emission wavelength mappings on the precursor solutions illustrate dominant emissions from DCTC$^-$ while the emission from TCNQ is quenched by the resonance energy transfer to DCTC$^-$. On the contrary, TCNQ in crystalline melamine is a bright fluorophore whose emission wavelength centered at 450 nm and slow fluorescence lifetimes of about 2 ns. Our method of encapsulating molecules into transparent melamine would make many other molecules fluorescencent in solids.
- Organisation(s)
- X-ray Structure Analysis Centre, Department of Inorganic Chemistry, Electronic Properties of Materials
- External organisation(s)
- Czech Academy of Sciences
- Journal
- ACS Applied Optical Materials
- Volume
- 2
- Pages
- 1128–1135
- No. of pages
- 8
- ISSN
- 2771-9855
- DOI
- https://doi.org/10.26434/chemrxiv-2023-945vj
- Publication date
- 08-2023
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103018 Materials physics
- Keywords
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/highly-luminescent-tcnq-in-melamine(533a7c9c-7eb0-4fe2-9a57-e258a63302f4).html