This journal is c The Royal Society of Chemistry 2012 Chem. Commun., 2012, 48, 401–403 401 Cite this: Chem. Commun., 2012, 48, 401–403 Solvent–solvent and solvent–solute interactions in a 3D chloroform clathrate with diorganotin macrocycles in the nano-sized poresw Ira´n Rojas-Leo´n, Jorge A. Guerrero-Alvarez,* Javier Herna´ndez-Paredes and Herbert Ho¨pfl* Received 25th September 2011, Accepted 28th October 2011 DOI: 10.1039/c1cc15957g A 3D clathrate of deuterochloroform molecules was formed in the presence of nano-sized macrocyclic molecules. Chlorinated aliphatic and aromatic hydrocarbons are important industrial chemicals with varied applications as solvents, pharmaceutical drugs, pesticides, reagents in organic synthesis and precursors for the production of polymeric materials such as PVC, Teflon and silicones. One of the most produced organochlorides is chloroform, mainly because of its use as non-polar and volatile solvent, cleaner, extraction agent and precursor for coatings based on Teflon. In research, deutero- chloroform is the most common solvent in NMR spectroscopy. 1 Current research concerning chloroform and other chlorinated solvents is, among others, related to the study of (i) thermo- dynamic, spectroscopic, structural and dynamic properties in the gaseous, liquid and solid state, (ii) processes occurring at solid–solid, solid–liquid, liquid–liquid and liquid–gaseous inter- faces including membranes, and (iii) interactions of solvent–solute systems. 2 Although knowledge concerning the interaction of solvent molecules in diverse environments is essential for the under- standing of a number of macroscopic phenomena in chemistry, biology and physics, there is still little information on the structural organization, binding properties and dynamics of chloroform and other halogenated solvents in the liquid and the solid state. 3 By contrast, for a number of other common solvents such as water and methanol, these and related topics have been investigated intensely during the past few years. 4 In order to provide a better insight into the microscopic organization of chloroform in liquid and solid phases, particularly in the presence of a solute, we report herein on the structural analysis of solvent–solvent and solvent–solute interactions in a unique 3D clathrate of chloroform molecules, which was formed in the presence of nano-sized macrocyclic molecules. We consider that responses to questions such as ‘‘How do chloroform molecules interact between each other in the presence of the solute?’’ and ‘‘Which are the predominant interactions between the solute and solvent?’’ are fundamental for a better under- standing of chemical and physical processes that occur in bulk liquid phases of halogenated solvents. Apart from contributions to solvation, dissolution and solubility, this kind of system has an impact also on fields such as molecular recognition, transport phenomena and chemical processes occurring at solid–liquid and liquid–liquid interfaces. Crystals of the composition [{Me 2 Sn(1,4-bisdtc)} 2 ]Á10CDCl 3 , with 1,4-bisdtc = N,N 0 -di(bicyclo[2.2.1]hept-2yl)-1,4-tetramethylene- bis(dithiocarbamate), were grown in an NMR tube by slow evaporation of CDCl 3 . In the absence of mother liquor the crystalline product rapidly degrades, which indicates loss of solvent. This is in agreement with the TG analysis (Fig. S1, ESIw), showing a continuous weight loss of 50% in the temperature range of 25–175 1C (calcd.: 51%). Single-crystal X-ray diffraction analysis at T = 100 K showed that the asymmetric unit consists of one molecular half of the organotin macrocycle, which is located at a crystallo- graphic inversion center, and five independent chloroform molecules, of which two are disordered: one over two sites (occ. 0.81 and 0.19) and the second over three sites (occ. 0.21, 0.33 and 0.46).z In the crystal structure, the chloroform molecules occupy 54% of the unit cell volume. The molecular dimensions of the 22-membered dinuclear organotin macrocycle are 8.4 Â 15.9 Â 19.9 A ˚ 3 , which make it a nano-sized compound (Fig. 1a and b). The only Lewis acidic and Lewis basic sites at the periphery of the macrocycle, tin and sulfur atoms, are connected to each other through weak SnÁÁÁS interactions with a distance of 3.95 A ˚ to give linear 1D chains along the axis a (Fig. 1c), which are completely embedded within the channels of a 3D clathrate formed by the crystal lattice deuterochloroform molecules (Fig. 2a). Each macrocycle forms close contacts with eighteen chloroform molecules through a total of 24 interactions, of which two are SÁÁÁCl, six are C–DÁÁÁS and sixteen are C–ClÁÁÁH contacts (Table S1, ESIw). 5 Two main factors determining the molecular association of a supramolecular assembly are the structure of the molecular building blocks and the intermolecular interactions they can establish. Chloroform is a tetrahedral molecule capable of forming ClÁÁÁCl and HÁÁÁCl contacts in four different space directions. This geometric characteristic is essential for the generation of 2D and 3D supramolecular networks, as it is Centro de Investigaciones Quı´micas, Universidad Auto ´noma del Estado de Morelos, Av. Universidad 1001, C.P. 62209 Cuernavaca, Me ´xico. E-mail: hhopfl@uaem.mx, jguerrero@uaem.mx; Fax: +52 777 329 7997; Tel: +52 777 329 7997 w Electronic supplementary information (ESI) available: Experimental details, spectroscopic data, NMR spectra, FAB + spectrum, TG curve, additional figures, and tables for intermolecular interactions. CCDC 841834. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c1cc15957g ChemComm Dynamic Article Links www.rsc.org/chemcomm COMMUNICATION Downloaded by University of New Mexico on 26 December 2011 Published on 11 November 2011 on http://pubs.rsc.org | doi:10.1039/C1CC15957G View Online / Journal Homepage / Table of Contents for this issue