Fluorescent macromolecular perylene diimides containing pyrene or indole units in bay positions
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Date
2010
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Abstract
Novel, symmetric and unsymmetric perylene diimide dyes with pyrene or indole units in the bay positions of the perylene ring were synthesized and characterized using FT-IR, 1H and 13C NMR, MS, UV-Vis spectra and cyclic voltammetry. The λmax in different solvents were in the range 526-585 nm and emission wavelengths of the dyes exhibited positive solvatochromism with increasing solvent polarity. Long wavelength emissions >750 nm of dyes with pyrene units displayed charge-separated state of perylene-pyrene system. Dyes with pyrene or indole units showed greater photostability in toluene than dyes which did not contain these bulky substituents. Incorporating electron-donating indole substituents lowered the band gap energies and, therefore, the HOMO energy levels were increased. The energy density and shape of the molecular orbitals were calculated theoretically. © 2009 Elsevier Ltd. All rights reserved.
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Charge transfer , Chemical bonds , Cyclic voltammetry , Energy gap , Ion exchange , Liquid crystal polymers , Mass transfer , Molecular orbitals , Solar cells , Solvents , Sulfur compounds , Toluene , Band gap energy , Bulky substituents , Charge-separated state , Different solvents , Electron-donating , Emission wavelength , Energy density , HOMO energy levels , HOMO-LUMO energies , HOMO-LUMO energy levels , Indole units , Long-wavelength emissions , Perylene rings , Perylenediimides , Perylenes , Photo-stability , Positive solvatochromism , Solvatochromisms , Solvent polarity , UV-vis spectra , chemical process , dye , fluorescence , hydrocarbon , solvent , synthesis , Electron transitions