Organic & Biomolecular Chemistry Dynamic Article Links Cite this: Org. Biomol. Chem., 2011, 9, 8340 www.rsc.org/obc PAPER Bis- and tris-naphthoimidazolium derivatives for the fluorescent recognition of ATP and GTP in 100% aqueous solution† Zhaochao Xu,‡ a,c Na Ri Song,‡ b Jong Hun Moon,‡ d Jin Yong Lee* d and Juyoung Yoon* a,b Received 8th August 2011, Accepted 19th September 2011 DOI: 10.1039/c1ob06344h Naphthoimidazolium groups can form unique ionic hydrogen bonds with anions as imidazolium moieties, and in addition, they are fluorescent, so no further elaborative synthesis is needed to introduce a fluorescent group. In this paper, three naphthoimidazolium derivatives were synthesized and studied for the recognition of nucleotides. Compound 1 composed of a single naphthoimidazolium group and quaternary ammonium group did not show any significant fluorescent changes with various anions and nucleotides, such as ATP, GTP, CTP, TTP, UTP, ADP and AMP. A tripodal compound 3 bearing three naphthoimidazolium groups and three quaternary ammonium groups, respectively, showed large fluorescence enhancements with UTP, CTP and TTP and moderate fluorescence enhancements with ATP and pyrophosphate and a fluorescence quenching effect with GTP. On the other hand, compound 2 bearing two naphthoimidazolium groups and two quaternary ammonium groups displayed a selective fluorescence enhancement with ATP and a selective fluorescence quenching effect with GTP in 100% aqueous solution. Introduction The recognition and sensing of nucleotides is an active area of research due to their biological significance. 1 For example, ATP is a universal energy source and an extracellular signaling mediator in many biological processes. 2 GTP acts as an energy source for protein synthesis and plays an important role in RNA synthesis and the citric acid cycle. 3 UTP is known to participate in enzymatic reactions, such as the many glycosylation processes that are catalyzed by glycosyltransferases and to serve as a donor for energy transduction in organisms. 4 Thymidine nucleotides are essential building blocks in DNA replication and cell division. 5 Although several highly sensitive and selective methods are available for their determination, including high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), enzyme-based methods, etc., there are still some problems due to the sophisticated chromatographic instrumentation and laborious procedures. Since sensors based on anion-induced changes in fluorescence are particularly attractive due to their simplicity and use for in vivo/in vitro imaging, the development of fluorescent a Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea. E-mail: jyoon@ewha.ac.kr; Fax: (+82) 2-3277-2384 b Department of Bioinspired Science, Ewha Womans University, Seoul 120- 750, Korea c Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China d Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea. E-mail: jinylee@skku.edu † Electronic supplementary information (ESI) available. See DOI: 10.1039/c1ob06344h ‡ These authors contributed equally to this work. chemosensors to sense various anions has attracted significant attention over the past few years. 6 Many fluorescent chemosensors have been designed for these nucleotides, 7 specifically for ATP, 8 GTP, 9 TTP, 10 UTP, 11 etc. Among them, our contributions of GTP 9a and ATP 8a utilizing imidazolium derivatives are included, in which imidazolium groups 12 can induce ionic hydrogen bonding interactions between the imidazolium (C–H) + and phosphate groups. Naphthoimidazolium groups can form these unique ionic hydrogen bonds and in addition, they are fluorescent, so no further elaborative synthesis is needed to introduce a fluorescent group. 13 In this paper, three naphthoimidazolium derivatives were syn- thesized and studied for the recognition of nucleotides. Compound 1 (Fig. 1) composed of a single naphthoimidazolium group and quaternary ammonium group did not show any significant fluorescent changes with various anions and nucleotides, such as ATP, GTP, CTP, TTP, UTP, ADP and AMP. On the other hand, tripodal compound 3 bearing three naphthoimidazolium groups and three quaternary ammonium groups, respectively, showed large fluorescence enhancements with UTP, CTP and TTP and moderate fluorescence enhancements with ATP and Fig. 1 Structures of compounds 1–3. 8340 | Org. Biomol. Chem., 2011, 9, 8340–8345 This journal is © The Royal Society of Chemistry 2011 Downloaded by Dalian Institute of Chemical Physics, CAS on 07 December 2011 Published on 19 September 2011 on http://pubs.rsc.org | doi:10.1039/C1OB06344H View Online / Journal Homepage / Table of Contents for this issue