| Abstract
| - The calix[4]arene platform has been used for the syntheses of novel rhenium(V) complexes that may have potential applications as radiopharmaceuticals. The N2S2-calix[4]arene rhenium complex could be synthesized under aqueous conditions and proved stable in PBS solution.
- The calix[4]arene platform was used for the syntheses of novel rhenium(V) complexes, that may have potentialapplications as radiopharmaceuticals. The reaction of ReO(PPh3)2Cl3 with tetradentate N2O2-calix[4]arene ligand8 in ethanol gave the novel mixed-ligand rhenium complex 9 with the structure ReO(N2O2-calix)OEt. Theconfiguration was elucidated by using a number of 1H NMR techniques. In 9, the ethoxy ligand could be easilyand quantitatively exchanged for another monodentate ligand to give complex 12. Tetradentate N2S2-calix[4]arene ligand 15 formed the rhenium complex 16 either via reaction with ReO(PPh3)2Cl3 in an organic solvent orby reaction with rhenium gluconate in an aqueous solution. Complex 16 showed good stability in phosphate-buffered saline solution (37 °C, 5 d). The crystal structures of a mono- and a bimetallic complex were determined.The bimetallic N2O2-calixarene complex dimer 11 crystallized in the monoclinic space group C2/c, with a =38.963(5) Å, b = 23.140(6) Å, c = 27.382(6) Å, β = 128.456(10)°, V = 19 333(7) Å3, Z = 8, and final R =0.0519. The monometallic N2S2 model complex 17 crystallized in the monoclinic space group Cc, with a =15.715(2) Å, b = 12.045(2) Å, c = 20.022(3) Å, β = 94.863(12)°, V = 3776.3(10) Å3, Z = 4, and final R =0.0342.
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