A theoretical approach to the influence of the macrocycle conformation on the molecular electronic structure in Mg-porphyrins

Nonplanar saddled (sad) ruffled (ruf) and domed (dom) conformations of the Mg-porphyrin (MgP) macrocycle in several degrees of deformation have been computed. These symmetrical distortion modes were induced in unsubstituted macrocycle using molecular definitions for calculations which permits us to achieve a systematical variation of the nonplanarity varying only a convenient geometrical parameter of the molecule. Series of nonplanar macrocycles like those synthesized in previous works employing peripheral substitutions are obtained. The procedure here used to induce deformations gives the possibility of investigating the modulator role of the out-of-plane distortions on the geometry and electronic properties of the porphyrin avoiding additional influences due to the substituents or the surrounding protein scaffolding.

[1]  L. D. Sparks,et al.  Metal dependence of the nonplanar distortion of octaalkyltetraphenylporphyrins , 1993 .

[2]  D. Melamed,et al.  Ruffling effects on porphyrin vibrations: normal-mode analysis for nickel octaethyltetraphenylporphine from resonance Raman and IR spectra of isotopomers , 1993 .

[3]  Kevin M. Smith,et al.  Consequences of Oxidation in Nonplanar Porphyrins: Molecular Structure and Diamagnetism of the .pi. Cation Radical of Copper(II) Octaethyltetraphenylporphyrin , 1994 .

[4]  H. Jaffe,et al.  Use of the CNDO Method in Spectroscopy. I. Benzene, Pyridine, and the Diazines , 1968 .

[5]  L. D. Sparks,et al.  Nonplanar distortion modes for highly substituted porphyrins , 1992 .

[6]  Kevin M. Smith,et al.  Conformational Flexibility in Dodecasubstituted Porphyrins , 1996 .

[7]  W. Jentzen,et al.  Structural characterization of synthetic and protein-bound porphyrins in terms of the lowest-frequency normal coordinates of the macrocycle , 1997 .

[8]  Kevin M Smith,et al.  Unusual picosecond 1(π, π∗) deactivation of ruffled nonplanar porphyrins , 1995 .

[9]  Kevin M. Smith,et al.  Structural and theoretical models of photosynthetic chromophores. Implications for redox, light-absorption properties and vectorial electron flow , 1988 .

[10]  Kevin M. Smith,et al.  Tetracycloalkenyl-meso-tetraphenylporphyrins as Models for the Effect of Non-planarity on the Light Absorption Properties of Photosynthetic Chromophores , 1990 .

[11]  Kevin M Smith,et al.  Nonplanar Porphyrins. X‐Ray Structures of (2,3,7,8,12,13,17,18‐ Octaethyl‐ and ‐Octamethyl‐5,10,15,20‐tetraphenylporphinato)zinc(II). , 1991 .

[12]  Craig J. Medforth,et al.  Conformational Study of 2,3,5,7,8,12,13,15,17,18-Decaalkylporphyrins , 1994 .

[13]  W. Jentzen,et al.  Nonplanar porphyrins and their significance in proteins , 1998 .

[14]  W. Goddard,et al.  Ruffling in a Series of Nickel(II) meso-Tetrasubstituted Porphyrins as a Model for the Conserved Ruffling of the Heme of Cytochromes c. , 1995, Journal of the American Chemical Society.

[15]  L. D. Sparks,et al.  Correlations between Raman frequencies and structure for planar and nonplanar metalloporphyrins , 1994 .

[16]  J. Stewart.  Optimization of parameters for semiempirical methods I. Method , 1989 .

[17]  Lars R. Furenlid,et al.  Crystallographic and EXAFS studies of conformationally designed nonplanar nickel(II) porphyrins , 1993 .

[18]  Kevin M Smith,et al.  STRUCTURAL HETEROGENEITY AND COORDINATION CHEMISTRY OF NICKEL(II) OCTAETHYL-MESO-NITROPORPHYRINS , 1994 .

[19]  Craig J. Medforth,et al.  Relationships between structural parameters and Raman frequencies for some planar and nonplanar nickel(II) porphyrins , 1991 .

[20]  L. D. Sparks,et al.  Macrocycle and substituent vibrational modes of nonplanar nickel(II) octaethyltetraphenylporphyrin from its resonance Raman, near-infrared-excited FT Raman, and FT-IR spectra and deuterium isotope shifts , 1993 .

[21]  J. M. García de la Vega,et al.  Molecular modeling of highly peripheral substituted Mg- and Zn-porphyrins , 2000 .