Abstract
Three symmetric alkylamino-substituted perylene bisimides with different n-alkyl chain lengths (n = 6, 12, or 18), 1,7-bis-(N,N-dialkylamino)perylene bisimides (1a–1c), were synthesized under mild condition and were characterized by 1H NMR, 13C NMR and high resolution mass spectroscopy. Their optical and electrochemical properties were measured using UV-Vis and emission spectroscopic techniques as well as cyclic voltammetry (CV). These compounds show deep green color in both solution and solid state, and are highly soluble in dichloromethane and even in nonpolar solvents such as hexane. The shapes of the absorption spectra of 1a–1c in the solution and solid state were found to be almost the same, indicating that the long alkyl chains could efficiently prevent intermolecular contact and aggregation. They show a unique charge transfer emission in the near-infrared region, of which the peak wavelengths exhibit strong solvatochromism. The dipole moments of the molecules have been estimated using the Lippert–Mataga equation, and upon excitation, they show larger dipole moment changes than that of 1,7-diaminoperylene bisimide (2). Moreover, all the dyes exhibit two irreversible one-electron oxidations and two quasi-reversible one-electron reductions in dichloromethane at modest potentials. Complementary density functional theory calculations performed on these chromophores are reported in order to rationalize their electronic structure and optical properties.
Highlights
In an effort to expand the scope of PBI-based chromophores available for designing systems for colorful dyes and self-assembly, we synthesized a series of blue dyes based on 1,7-diaminoperylene bisimides [76]
We report on the introduction of different long alkyl chains of 1,7-diaminoperylene bisimide (2) affording chromophores (1a–1c) that are deep green in color and that readily undergo two irreversible one-electron oxidations and two quasi-reversible one-electron reductions
The dinitration can be achieved by a reaction of perylene bisimide (4) with cerium (IV) ammonium nitrate (CAN) and HNO3 under ambient temperature for 48 h [60], giving 1,6- and 1,7-dinitroperylene bisimides in high yields of ca. 80%
Summary
Derivatives of perylene bisimide (PBI) have continuously attracted significant attention due to their applications in molecular electronic devices, such as light-emitting diodes [1,2,3,4,5], LCD color filters [6,7], organic field-effect transistors (OFETs) [8,9,10,11,12,13], light-harvesting arrays [14,15], photovoltaic cells [16,17,18,19,20,21,22,23,24,25], molecular wires [26,27], and photochromic materials [28,29]. The electronic characteristics of PBIs can be fine-tuned by introducing different substituents at the bay-positions (1,6,7,12-positions) of the conjugated perylene core. Based on these rules, a number of perylene bisimide derivatives with either electron-withdrawing or electron-donating groups have been reported in the literature, including: (a) perfluoroalkyl-substituted PBIs [56,57]; (b) cyano-substituted. A promising strategy for introducing substituents onto the PBI core is bromination or chlorination of perylene dianhydride. Replacement of these halogens is readily executed by traditional substitution reactions or by metal-catalyzed cross-coupling reactions. We report on the introduction of different long alkyl chains of 1,7-diaminoperylene bisimide (2) affording chromophores (1a–1c) that are deep green in color and that readily undergo two irreversible one-electron oxidations and two quasi-reversible one-electron reductions
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