Solvent effects on the molecular recognition of anions

Alireza Shokri, Steven R. Kass
2013 Chemical Communications  
S2 Experimental General. All reactants and reagents including (Ph 3 P) 2 NCl and Bu 4 NX (X = Cl, OAc, NO 3 , H 2 PO 4 , and HSO 4 ) were bought from Sigma-Aldrich. Tetrahydrofuran was dried by refluxing it over sodium metal under argon and subsequently was distilled. TLC analyses were performed on precoated (250 mm) silica gel 60 F-254 plates (Merck) and were visualized by staining with KMnO 4 or with a hand-held UV lamp. Diol 1 was synthesized as previously reported. S1 All deuterated
more » ... deuterated solvents were purchased from Cambridge Isotope Laboratories and used from freshly opened bottles except for CDCl 3 and CD 3 CN which were dried over activated 3 Ǻ molecular sieves for several days. Proton NMR spectra were recorded on Varian VI-500 and VI-300 MHz instruments at different temperatures as indicated, and the resulting chemical shifts are reported in parts per million (δ) relative to the residual solvent peak. For 13 C spectra the residual acetonitrile signal at 1.39 ppm was used whereas for 19 F an external reference sample of CFCl 3 was set to 0.00 ppm. A Bruker BioTOF II electrospray ionization-time of flight mass spectrometer with polyethylene glycol 400 as an internal standard was used to obtain an exact mass measurement of 2. Binding Constant Determinations. Dilute solutions of 1 and 2 (2.5 mM) were titrated with anions salts (30-100 mM) at different temperatures. The changes in the chemical shifts of the hydroxyl groups in 1 and 2 were followed and nonlinear plots of the titration data (i.e., Δδ versus the concentration of the guest) were fit to a 1:1 binding equation using the Solver add-on program to Microsoft Excel 2010 to obtain the binding constants. 17 Representative data for both hosts are given in the supporting information. meso-1, 1,1,6,6,. A dry two-necked round bottomed flask was equipped with a magnetic stirring bar, a reflux condenser with an argon inlet, Electronic Supplementary Material (ESI) for Chemical Communications This journal is
doi:10.1039/c3cc46961a pmid:24189586 fatcat:5alq7npvsrcibierrn346ylyje