CREATED USING THE RSC COMMUNICATION TEMPLATE (VER. 2.1) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS COMMUNICATION www.rsc.org/[journal] | [journal name] This journal is © The Royal Society of Chemistry [year] [journal], [year], [vol], 00–00 | 1 Organic salt inclusion: the first crystal structures of anion complexes of N-confused calix[4]pyrrole Gareth W. Bates, a Maartin Kostermans, b Wim Dehaen,* ,b Philip A. Gale,* ,a and Mark E. Light a Receipt/Acceptance Data [DO NOT ALTER/DELETE THIS TEXT] Publication data [DO NOT ALTER/DELETE THIS TEXT] 5 DOI: 10.1039/b000000x [DO NOT ALTER/DELETE THIS TEXT] The first crystal structures of anion complexes of N-confused calix[4]pyrrole are presented showing chloride binding to the three ‘unconfused’ pyrrole NH groups and imidazolium inclusion in the calixpyrrole cup. 10 The synthesis of N-confused calixpyrrole was reported by Dehaen and co-workers in 1999. 1 In this macrocycle one of the pyrrole rings is linked via the 2- and 4-positions rather than the 2- and 5- positions. We wished to investigate whether the ‘confused’ macrocycle would employ both the ‘regular’ pyrrole NH groups 15 and the ‘confused’ pyrrole NH group in anion complexation in the solid state and also whether confused calixpyrrole would show organic salt inclusion properties as had previously been demonstrated with the parent macrocycle. 2 Commercially available ionic liquids 3 have attracted much attention 20 recently as alternate environmentally friendly solvents in which to carry out a variety of organic and inorganic synthetic reactions 4 and as reagents themselves. 5 A wide variety of ionic liquids consisting of alkylated imidazolium salts are commercially available. The inclusion of a variety of imidazolium and pyridinium ionic liquids 25 in calix[4]pyrrole 4 has illustrated the capacity of this ancient class of macrocycle to bind large charge diffuse cations in addition to anionic guests. Compound 1 was synthesised according to literature methods. 1 Complexes of 1 with the imidazolium ionic liquids were prepared 30 by slow evaporation of dichloromethane solutions of the receptor in the presence of either excess 1-ethyl-3-methylimidazolium chloride (EMIM Cl) or 1-butyl-3-methylimidazolium chloride (BMIM Cl). The composition of the bulk crystalline material was confirmed by 1 H NMR spectroscopy. 35 Both complexes adopt similar structures and in the following discussion data for the EMIM Cl complex‡ are given followed by 40 data for the BMIM Cl complex¶ in parentheses. The imidazolium cation sits upright in the bowl of the receptor (Figure 1) such that one of the two adjacent aromatic hydrogens interacts with the π cloud of one of the pyrroles; the centroid to H distance and the centroid … H-C angle are 2.476(3)Å and 45 159.35(8)Å respectively [2.426(4)Å and 158.89(9)°] These interactions are depicted in Figure 2 as dotted lines to the nitrogen of the pyrrolic ring. The plane of the imidazolium ring makes a tilt angle from the horizontal of the calixpyrrole of 72.23(5)° [75.91(4)°] and is twisted from the orthogonal by 61.49(4)° 50 [66.80(7)°] (Figure 1). a School of Chemistry, University of Southampton, Southampton, UK SO17 1BJ. Fax: +44 (0)23 8059 6805; Tel: +44 (0)23 8059 3332; E- mail: philip.gale@soton.ac.uk b Department of Chemistry, University of Leuven, Celestijnenlaan 200F B- 3001Leuven, Belgium; E-mail wim.dehaen@chem.kuleuven.ac.be † Electronic Supplementary Information (ESI) available: [details of any supplementary information available should be included here]. See http://dx.doi.org/10.1039/b000000x/