Tetrathiafulvalene-calix[4]pyrroles: synthesis, anion binding, and electrochemical properties.
The syntheses of monotetrathiafulvalene-calix[4]pyrrole 5 and bistetrathiafulvalene-calix[4]pyrrole 6, prepared from the acid-catalyzed condensation of monopyrrolo[3,4-d]tetrathiafulvalene (MPTTF, 7) with acetone in the presence of tripyrrane 8 and dipyrromethane 9, respectively, are described. Compound 5 and the previously reported tetrathiafulvalene-calix[4]pyrrole 4 both adopt a 1,3-alternative conformation in the solid state, as determined from X-ray crystallographic analysis. The anion binding properties of the tetrathiafulvalene-calix[4]pyrroles 5 and 6, as well as those of the parent meso-octamethylcalix[4]pyrrole (1), were investigated in acetone using (1)H NMR spectroscopic and isothermal titration calorimetry (ITC) techniques and, within the error limits of the methods, were generally found to give concordant results. On the basis of the results of the ITC studies carried out in 1,2-dichloroethane, increasing the number of tetrathiafulvalene units annulated to the calix[4]pyrrole system serves to enhance the anion binding affinities substantially but at the price of lowered selectivity. Cyclic voltammetry (CV) studies, carried out in 1,2-dichloroethane, provided evidence of an anion-dependent electrochemical response with Cl(-) and Br(-) ions. This response was particularly dramatic in the case of the monotetrathiafulvalene-calix[4]pyrrole 5, with a DeltaE(max) of -145 mV being seen after the addition of approximately 1 equiv of Cl(-) ion.
Department of Chemistry, University of Southern Denmark (Odense University), Campusvej 55, DK-5230 Odense M, Denmark.
Kent A
KA
Nielsen
Won-Seob
WS
Cho
Joël
J
Lyskawa
Eric
E
Levillain
Vincent M
VM
Lynch
Jonathan L
JL
Sessler
Jan O
JO
Jeppesen
D000838:Anions; D047250:Calixarenes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D017186:Titrimetry
D000838:Anions; D006571:Heterocyclic Compounds; D011166:Porphyrins; C469811:calix(4)pyrrole; D047250:Calixarenes; C063887:tetrathiafulvalene