A semiempirical MO study of the electronic structure and excited states of the Tris(2,2?-bipyridyl)Iron(II) and Tris(glyoxal-Bis-N-methylimine)iron(II)Ions

Binding of inert metal complexes to deoxyribonucleic acid detected by linear dichroism

“…The A2 band is hidden in the large negative LD band of DNA from the purine-pyrimidine 7r transitions, however positive sign of the E component proves that the Fe(dipy)32÷ complex is associated with its C3-axis preferentially perpendicular to the DNA helix-axis (I). This conclusion is supported by the observation of positive signs on the 520-480 nm bands which are theoretically [4] less differentiated than the one with the dipy compound with no excition band to reveal the predominant orientation. On the basis of the positive bands at low energy (E symmetry) [4] we suggest that the orientation may be similar to that in the Fe(dipy)3-DNA complex.…”

“…This conclusion is supported by the observation of positive signs on the 520-480 nm bands which are theoretically [4] less differentiated than the one with the dipy compound with no excition band to reveal the predominant orientation. On the basis of the positive bands at low energy (E symmetry) [4] we suggest that the orientation may be similar to that in the Fe(dipy)3-DNA complex. On the other hand the complete lack of CD may suggest a further lower order within the complex and a larger average N-M distance.…”

“…The metal complexes were obtained as in [4]. Calf-thymus DNA, Sigma type I, was used without further purification, either in 0.2 M NaC1 as an ionic medium or at an ionic strength approx.…”

A model for the interpretation of the absorption and circular dichroism spectra of tris(di-imine) complexes of iron(II) and ruthenium(II)

“…We can therefore distinguish three types of m.1.c.t. transitions: (i) the two mentioned above, E,(e+a2)(4) and E2(e-+e)(5), with a large electric dipole moment and hence with strong absorption, and having a small magnetic dipole moment; (ii) the A2(e--te) (3) and E(a1+e)(3) transitions, with a large magnetic and a small electric dipole moment, hence showing strong c.d. bands; (iii) one A2(al+a2)(2) transition which carries neither a large electric nor a large magnetic dipole moment.…”

PPP (Peel) calculations on iron porphyrins and iron phthalocyanine. Charge distribution and charge transfer

“…The method has also been extended to include lone pair orbitals on N [23] and 0 [24] as well as metal 3d, 4s, and 4p orbitals. Until now, metal parameters have been developed for Cu [25,26] and Fe [27]. The method has been successfully applied on the spectra as well as other properties of copper porphine [28] as well as copper phthalocyanine [29].…”