Models of photosynthetic chromophores: molecular structure of the bacteriochlorin (2,3,12,13-tetrahydro-5,10,15,20-tetraphenylporphinato)(pyridine)zinc(II)

Three high-precision structures of bacteriochlorophyll (BChl) have been reported previously; a free base, a nickel synthetic derivative, and methyl bacteriopheophoride, derived from bacteriopheophytin pigment found in reaction centers. An x-ray determination of the structure of the bacteriochlorin (2,3,12,13-tetrahydro-5,10,15,20-tetraphenylporphinato)(pyridine)zinc(II) is reported herein. The present results allow an assessment of the structural changes resulting from the progressive saturation of the pyridine molecule. The new structural data were used to test the validity of the INDO/S semiempirical model in predicting spectral properties of the bacteriochlorins. 2 refs., 4 figs., 3 tabs.