Straightforward synthesis of photoactive chalcogen functionalized benzimidazo[1,2-a]quinolines
| Autor: | Daniel S. Rampon, Paulo H. Schneider, Felipe Lange Coelho, Juliana Maria Forain Miolo Schneider, Fabiano Severo Rodembusch, Ricardo S. Schwab, Rodrigo Silva |
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| Rok vydání: | 2019 |
| Předmět: |
Chemistry
02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Photochemistry 01 natural sciences Catalysis 0104 chemical sciences Chalcogen symbols.namesake Intersystem crossing Nucleophilic aromatic substitution Stokes shift Intramolecular force Excited state Materials Chemistry symbols Nucleophilic substitution Knoevenagel condensation 0210 nano-technology |
| Zdroj: | New Journal of Chemistry. 43:11596-11603 |
| ISSN: | 1369-9261 1144-0546 |
| DOI: | 10.1039/c9nj01948k |
| Popis: | A series of new organochalcogen derivatives of benzimidazo[1,2-a]quinolines were synthesized in moderate to excellent yields and in short reaction times from chalcogen benzimidazoles, in a straightforward synthetic procedure, through transition-metal-free cascade reactions involving a sequential intermolecular aromatic nucleophilic substitution (SNAr), followed by an intramolecular Knoevenagel condensation. Both the sulfur and selenium derivatives presented similar photophysical properties, with absorption maxima located in the UV region (∼355 nm) related to spin and symmetry allowed electronic p–p* transitions, and fluorescence emission located in the violet-blue region (∼440 nm) with a relatively large Stokes shift (∼90 nm). The fluorescence quantum yields were slightly influenced by the chalcogen, with the sulfur derivatives presenting higher values than the selenium analogues, probably due to the intersystem crossing allowed by the selenium atom. Moreover no clear evidence for charge transfer in either compound in the ground and excited states was observed. |
| Databáze: | OpenAIRE |
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