Tetrathiafulvalene (TTF) systems are of interest mainly due to their potential as electron donors in organic metals and superconductors.[" However, combining the electroactive moiety of the TTF system with different aza-, thiaor oxacrown chains leads TTF chemistry into the field of cation-sensitive sensors. We have recently reportedc3] the preparation of two new types of TTF-based macrocyclic ligands incorporating aza-and oxacrown ethers, the "bow tie" TTF (type A) and the "cage" TTF (type B).
A BBis-TTF crowns of type A did show some complexation with group I a ions as well as AgO, thus cyclic voltammetry (CV) investigations as well as 'H-NMR studies of the TTF derivative 1 revealed significant changes upon complexation.c4] The changes were in accordance with the size and nature of the crown. Bis-crown TTFs having shorter chains (1-2 oxygens) showed no complexation at all, and if the oxygen atoms were substituted by sulfur, only silver ions affected the cyclic ~oltammogram.[~1 In all the cages of typeB prepared so far the linking bridges have been too short (CH,CH,(ACH,CH,),; n = I , A = 0, N-Me; n = 2, A = 0) and rigid to show any complexation. We therefore anticipated that a cage-TTF with a more flexible and larger ligand system might give better complexation and hence show a significant change of redox properties upon complexation. Molecular systems related to the ones presented here which contain two or more 1,7-diaza-4,10,13-trioxocyclopentadecane units have been shown to possess high selectivity with regard to ionic as well as molecular recognit i~n , '~. 61 and were therefore chosen in order to produce a potential redox-active sensor system.The tetrathiafulvalenes 7 and 8 reported herein are the first examples of tetrathiafulvalene-cryptands incorporating 1,7-diaza-4,10,13-trioxocyclopentadecane units. We have previously[31 used disodium 1,3-dithiol-2-thione-4,5-dithiolate under "template-controlled reaction conditions" with bis-alkylating reagents to form macrocycles on addition of cesium carbonate to the reaction mixture. This resulted in enhanced formation of higher oligomers. Disodium-l,3dithiol-2-thione-4,5-dithiolate is rapidly oxidized in air and must be handled under an inert atmosphere. Although cesium carbonate was added to the reaction mixture, sodium ions are still present and competition takes place between the cations. This problem was avoided by using the pure dicesium salt 3. In addition, we found that 3 was easily isolated in almost quantitative yields from the dibenzoate 2c7] simply by debenzoylation with cesium hydroxide. In contrast to the corresponding disodium thiolate, the purple, crystalline cesium salt 3 is much more stable. 2 3The best yields were obtained when dimethylformamide (DMF) was used as solvent. With carefully adjusted reaction conditions, surprisingly high yields of the higher oligomers could be obtained.Cesium salt 3 was reacted with bis(chloroacety1)diaza-[18]-crown-6, 4, to afford either 5 or 6. Slow (48 hours) simultaneous addition of equimolar amounts of DMF solut...
