THE SYNTHESIS AND SPECTROSCOPIC PROPERTIES OF MACROCYCLIC POLYETHERS CONTAINING 2 DIFFERENT AROMATIC MOIETIES AND THEIR [2]CATENANES INCORPORATING CYCLOBIS(PARAQUAT-P-PHENYLENE)

The synthesis of six derivatives of bis-p-phenylene-34-crown-10 (BPP34 C10) in which one or both of the p-phenylene rings are replaced by oth er pi-electron-rich aromatic ring systems, and their subsequent use as templates for the self-assembly of the tetracationic cyclophane cyclo bis(paraquat-p-phenylene) and thus the construction of [2]catenanes, a re described, The p-phenylene rings in BPP34C10 have been replaced var iously by p-xylyl units, 1,5-,1,6-, 2,6- and 2,7-naphtho units, and a naphthalene-2,6-dimethylyl ring system in the six new crown ether deri vatives, Five of the [2]catenanes have the potential to exist in solut ion as equilibrating mixtures of two translational isomers, the propor tions of which have been determined in solution by dynamic H-1 NMR spe ctroscopy. The absorption spectra and luminescence properties (fluores cence, phosphorescence, and excitation spectra, excitation state lifet imes, and fluorescence quantum yields) of the BPP34C10 derivatives (in which one of the p-phenylene rings has been replaced by either a p-xy lyl unit or a naphthalene-2,6-dimethylyl unit or where both of the p-p henylene rings have been replaced, one by a p-xylyl unit and the other by a 1,5-naphtho unit) and their derived [2]catenanes, with cyclobis( paraquat-p-phenylene) as the interlocking cyclophane component. have b een investigated. Comparison with the properties of simple model compo unds shows the presence of intra-and intermolecular electronic interac tions between the component units of the crown ethers and catenanes. T he main consequences of these interactions in the crown ethers are sma ll perturbations in the absorption spectra of the two chromophoric uni ts, and strong changes in the luminescence properties due to the occur rence of intercomponent energy-transfer processes and charge-transfer (CT) interactions. In the [2]catenanes, perturbations in the absorptio n spectra of the component units of the crown ether and tetracationic cyclophane, accompanied by the appearance of CT absorption bands in th e visible region, and complete luminescence quenching caused by the pr esence of low-energy CT levels are observed.