5,10,15,20-Tetra(4-n-butylphenylethynyl) has been synthesised from 4-n
-butylphenylpropynal and converted into its zinc(II) and lead(II) comp
lexes. The solution electronic spectra of these porphyrins are compare
d to the analogous complexes of 5,10,15,20-tetra(trimethylsilylethynyl
)porphyrin. The aryl rings of the tetra(4-n-butylphenylethynyl)porphyr
in extend the porphyrin chromophore, resulting in an increase in the o
scillator strength and a bathochromic shift of about 600 cm(-1) in all
the absorption bands. Metallation with lead(II) results in a larger b
athochromic shift of about 1400 cm(-1), when compared with zinc(II), T
he crystal structure of the pyridine zinc complex of 5,10,15,20-tetra(
4-butylphenylethynyl)porphyrin shows that the molecule has a large app
roximately planar pi-system. Pairs of diagonally off-set pi-pi stacked
porphyrins pack into a layer structure. Each pyridine ligand is locat
ed in a pocket defined by four butyl chains.