Synthesis, characterization, and DFT study of polycyclic aromatic hydrocarbon precursors, 1,4-diiodo-2,3,5,6-tetraarylbenzene and 1,4-bis(4-bromophenyl)-2,3,5,6-tetraarylbenzene
摘要:
The molecular structure and spectroscopic properties of 1,4-diiodo-2,3,5,6-tetraarylbenzene and 1,4-bis(4-bromophenyl)-2,3,5,6-tetraarylbenzene have been investigated by density functional theory (DFT), H-1 NMR, C-13 NMR, IR spectroscopy, and elemental analysis. These compounds are the precursors for the synthesis of large polycyclic aromatic hydrocarbons (PAHs). Because of the flexibility of aliphatic chains, DFT calculations of C-13 NMR chemical shifts were only calculated in the aromatic region by introducing H atoms replacing the aliphatic chains and H-1 NMR chemical shifts were neglected. A drawback of excluding aliphatic chains in the IR calculation was the loss of vibrational modes for C-H stretching and bending. Due to this significant loss of information, the aliphatic chains were included in the IR calculations. The comparison of the calculated C-13 NMR and IR parameters with the experimental spectroscopic data reveals good agreement and thus confirmed the suggested molecular structures. In addition, the electronic structure of these compounds was discussed based on HOMO-LUMO analyses. (c) 2012 Elsevier B.V. All rights reserved.
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