Porphyrins for optical limiting applications
A number of symmetric porphyrins containing both zinc(II) and lead(II) central metal ions have been prepared. Several routes to these compounds have been investigated and their merits evaluated. The conjugation of the chromophores has been extended by the inclusion of different trans- substituted arylethynyl substituents in the meso-position. An improved multigram method for the preparation of [bis-trimethylsilyethynylporphinato]zinc(II), which does not necessitate chromatographic purification, is described. The use of [5-triisopropylsilylethynylporphinato]zinc(II) for the preparation of donor/acceptor prophyrins via Sonogashira coupling, several of which were prepared, is also described. Investigations of the binding of 4(3H)pyrimidone with [5,5'-bis-[10,20-bis(3,5-di-tert-butylphenyl)-15-tri-iso-propylsilylethynyl-porphinyl]-1,3-butyn-1,4-diyl]dizinc(II) were made. The association constant was found to be 2500 ± 140 mol-1 (ΔG = -4.6 Kcal/mol), significantly greater than that for 4(3H)pyrimidone alone (444 ± 5 mol-1), as determined by NMR dilution experiments. The crystal structures of [5,15-bis(3,5-bis-tert-butylphenyl)porphinato]zinc(II), [5,15-bis-(3,5-di-tert-butylphenyl)-10,20-bis-triisopropylsilylethynylporphinato]lead(II), [5,10,15,20-tetrakis-triisopropylsilylethynylporphinato]lead(II), 5,15-bis-(3,5-bis-tert-butylphenyl)-10,20-bis-phenylethynylporphyrin, [5,15-bis-(3,5-bis-tert-butylphenyl)-10,20-bis-(3-hydroxy-3-methyl-butynyl)porphinato]zinc(II),5,10,15,20-tetrakis-triisopropylsilylethynylporphyrin and [5,15-bis-(3,5-bis-tert-butylphenyl)-10-(4-N, N-dimethylaminophenylethynyl)-20-triisopropylsilylethynylporphinato]zinc(II) are also described.