Synthesis, structures, and ligating ability of 4-tert-butylcalix[n]arene (iso)nicotinoylate Eun Ji Kim, Jungmin Ahn, Haeri Lee, Tae Hwan Noh ⇑ , Ok-Sang Jung ⇑ Department of Chemistry, Pusan National University, Pusan 609-735, Republic of Korea article info Article history: Received 2 December 2011 Revised 24 December 2011 Accepted 26 December 2011 Available online 2 January 2012 Keywords: Absorption spectra 4-tert-Butylcalix[n]arene (iso)nicotinoylate Crystal structures Cobalt(II) complexes Partial substitution abstract 4-tert-Butylcalix[n]arenes react with an excess of (iso)nicotinoyl chloride, yielding selectively n-2 acyl- ated products, calix[n]-(nico) n2 (OH) 2 , (calix = 4-tert-butylcalix[n]arene; n = 4, 6, and 8; nico = (iso)nicoti- noylate) of alternate conformations. Their structures were determined by X-ray single crystallography and NMR spectra. The UV–vis spectra indicated that a new absorption band of the complexes appears upon the addition of cobalt(II) dichloride, and its crystal structure was resolved. Ó 2011 Elsevier Ltd. All rights reserved. Functionalized calix[n]arenes have been intriguing molecular building blocks for the construction of defined structural supramo- lecular systems, 1–5 owing to their potential application as sensors, catalysts, separation processes, enzymatic models, and iono- phores. 6–11 Calix[n]arenes can be functionalized in various ways at the phenolic hydroxyl groups, the so-named lower rim, and/or at the para position of the phenolic rings, known as the upper rim. 1,2,12,13 Synthesis of desirable calix[n]arene derivatives is essen- tial in order to modulate their conformation via electronic and ste- ric effects, including weak interactions. (Iso)nicotinoylate groups substituted into the lower rim of 4-tert-butylcalix[n]-arenes can be utilized as new multi-N-donor tectonics in the structural and functional modifications of their core molecular architecture which comprises a hollow cavity formed by a hydrophobic upper rim and a hydrophilic low rim. The (iso)nicotinoyl-containing pendants possess characteristic properties such as a potential multidentate ligand, an sp 2 angle around C@O(120°), a malleable length, con- formational nonrigidity, and manageable solubility. 14–18 In this context, we here describe a facile synthesis of unique partial substituted products, calix[n]-(nico) n2 (OH) 2 , (calix = 4-tert-butyl- calix[n]-arene; n = 4, 6, 8; nico = (iso)nicotinoylate) via steric hindrance along with their ligating ability with COCl 2 species. This produces the chemical repertoire of the calixarenes, since it provides easy access to novel ligands, allowing the synthesis of supramolecular materials for recognition. 0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.tetlet.2011.12.112 ⇑ Corresponding authors. Tel.: +82 51 510 2591; fax: +82 51 516 7421. E-mail addresses: nthjjang@pusan.ac.kr (T.H. Noh), oksjung@pusan.ac.kr (O.-S. Jung). O OH O m N 2 OH OH m 2 4-tert-butylcalix[n]arene = N N = , m = 1 (1a), 2 (2a), 3 (3a) N , m = 1 (1b), 2 (2b), 3 (3b) N O Cl N CoCl 2 Scheme 1. Overall procedure. Tetrahedron Letters 53 (2012) 1240–1244 Contents lists available at SciVerse ScienceDirect Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet