Synthesis, Structural, and Photophysical Properties of the First Member of the Class of Pyrene‐Based [4]Helicenes. Issue 26 (1st August 2013)

• Record Type: Journal Article
• Authors: Hu, Jian‐Yong; Feng, Xing; Paudel, Arjun; Tomiyasu, Hirotsugu; Rayhan, Ummey; Thuéry, Pierre; Elsegood, Mark R. J.; Redshaw, Carl; Yamato, Takehiko
• Is Part Of: European journal of organic chemistry. Issue 26(2013)
• Page Start: 5829
• Page End: 5837
• Publication Date: 2013-08-01
• Subjects: Fused‐ring systems -- Wittig reactions -- Cyclization -- Helical structures -- Optoelectronic properties; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201300487
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: A convenient route to a new class of pyrene‐based [4]helicenes is presented. Wittig reaction of 7‐ tert ‐butyl‐1, 3‐dimethyl‐5‐formylpyrene with benzyltriphenylphosphonium salts in the presence of n BuLi afforded 7‐ tert ‐butyl‐1, 3‐dimethyl‐5‐(phenylethenyl)pyrenes, from which 4, 5‐naphthalene annulated aromatic [4]helicenes, namely 7‐ tert ‐butyl‐1, 3‐dimethyl‐13‐methoxydibenzo[ ij, no ]tetraphene and 7‐ tert ‐butyl‐1, 3, 12, 14‐tetramethyldibenzo[ ij, no ]tetraphene, were obtained by photoinduced intramolecular cyclization. The chemical structures of these [4]helicenes were determined on the basis of their elemental analyses and spectroscopic data. The helicity in the synthesized [4]helicene induced by the presence of the second methyl group in the fjord region is discussed in detail. The photophysical and electrochemical properties of these newly developed [4]helicenes were fully investigated by UV/Vis absorption and photoluminescence spectrphotometry, and cyclic voltammetry (CV), and the crystal structures were determined for two examples. Abstract : A convenient route to a new class of pyrene‐based [4]helicenes is presented along with their optoelectronic properties. The introduction of two methyl groups in the fjord region of the [4]helicene gives a more distorted structure and leads to a remarkable redshift of the absorption band.