Chiral supramolecular thiophene fluorophore consisting of thiophenecarboxylic acid derivatives Takaya Kimoto a , Naoki Shiota a , Takafumi Kinuta a , Tomohiro Sato a , Nobuo Tajima b , Hayato Tokutome c , Reiko Kuroda c , Michiya Fujiki d , Yoshio Matsubara a , Yoshitane Imai a, * a Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan b Computational Materials Science Center, National Institute for Materials Science 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan c Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan d Graduate School of Materials Science, Nara Institute of School and Technology, Takayama, Ikoma, Nara 630-0192, Japan article info Article history: Received 29 June 2011 Received in revised form 27 July 2011 Accepted 27 July 2011 Available online 2 August 2011 Keywords: Chiral Circularly polarized luminescence (CPL) Fluorescence Supramolecule Thiophene abstract Solid-state chiral supramolecular thiophene fluorophore has been successfully prepared by using chiral (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This chiral supramolecular thiophene fluorophore is formed by assembling chiral 2 1 -helical columnar network structures composed of (R)-1-(2-naphthyl)ethylamine and 5-bromothiophene-2-carboxylic acid. This supramolecular organic fluorophore exhibits circularly polarized luminescence (CPL) even in the solid state. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The solid-state optical property of organic compounds finds remarkable application in the development of new functional or- ganic materials. The solid-state organic fluorescence property, in particular, has attracted considerable attention in the field of op- toelectronics owing to its application in organic electrolumines- cence (EL) devices and optical sensors. 1 Therefore, many solid-state organic fluorophores composed of a single organic molecule have been reported, of which two-component supramolecular organic fluorophores have recently attracted greater attention. 2 However, most of the previously reported supramolecular organic fluo- rophores lack chirality and hence do not possess solid-state chiral optical properties, such as solid-state circular dichroism (CD) or circularly polarized luminescence (CPL) properties. We recently developed a solid-state chiral supramolecular or- ganic fluorophore composed of (R)-1-(2-naphthyl)ethylamine [(R)- 1] as the chiral component molecule and 2-anthracenecarboxylic acid as the fluorescent component molecule. 3 The structural char- acteristic of this chiral supramolecular organic fluorophore is that it is composed of a 2 1 -helical columnar hydrogen- and ionic-bonded network structure formed by the association of (R)-1 and 2- anthracenecarboxylic acid. The advantage of these supramolecu- lar systems is that their physical and chemical properties can be altered by changing the component molecules. Recently, a large number of organic functional materials con- sisting of a polythiophene backbone have been reported. 4 These polythiophene compounds show various electrochemical and photochemical properties. Therefore, it is expected that novel solid- state chiral supramolecular fluorophores may be prepared by using thiophene derivatives as one of the component molecules in su- pramolecular complexes. In this study, we prepare a novel solid-state chiral supramo- lecular thiophene fluorophore with (R)-1 , and study its solid-state optical properties and crystal structures. The following three ba- sic thiophene acid derivatives are used for the preparation: 2- thiophenecarboxylic acid (2a), 5-chlorothiophene-2-carboxylic acid (2b), and 5-bromothiophene-2-carboxylic acid (2c). * Corresponding author. Tel.: þ81 06 6730 5880x5241; fax: þ81 06 6727 2024; e-mail address: y-imai@apch.kindai.ac.jp (Y. Imai). Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet 0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.tet.2011.07.086 Tetrahedron 67 (2011) 7775e7779