TY - JOUR
T1 - Structural, spectroscopic, and reactivity comparison of xanthene- and dibenzofuran-bridged cofacial bisporphyrins
AU - Chang, Christopher J.
AU - Baker, Erin A.
AU - Pistorio, Bradford J.
AU - Deng, Yongqi
AU - Loh, Zhi Heng
AU - Miller, Scott E.
AU - Carpenter, Scott D.
AU - Nocera, Daniel G.
PY - 2002/6/17
Y1 - 2002/6/17
N2 - A comparison of the structure, spectroscopy, and oxygen atom-transfer reactivity of cofacial bisporphyrins anchored by xanthene (DPX) and dibenzofuran (DPD) pillars is presented. The synthesis and characterization of dicopper(II) and dinickel(II) complexes of DPD completes a homologous series of homobimetallic zinc(II), copper(II), and nickel(II) complexes for both cofacial platforms. X-ray crystallographic analysis of the parent free-base porphyrins H4DPX (1) and H4DPD (5) confirms the face-to-face arrangement of the two porphyrin macrocycles with a large available range of vertical pocket sizes: 1 (C80H92Cl2N8O), triclinic, space group P, a = 13.5167(12) Å, b = 21.7008(18) Å, c = 23.808(2) Å, α = 80.116(2)°, β = 76.832(2)°, γ = 80.4070(10)°, Z = 4; 5 (C80H83N8O2), monoclinic, space group C2/c, a = 22.666(2) Å, b = 13.6749(14) Å, c = 42.084(4) Å, β = 94.554(2)°, Z = 8. EPR spectroscopy of dicopper(II) derivatives Cu2DPX (3) and Cu2DPD (7) complements the crystallographic studies by probing intramolecular metal-metal arrangements in frozen solution. Exciton interactions between the porphyrin subunits in fluid solution are revealed by steady-state and time-resolved electronic absorption and emission spectroscopy. The resulting compilation of structural and spectroscopic data provides a benchmark for the use of these and related platforms for the activation of small-molecule substrates. A structure-function relation is developed for the photoinduced oxygen atom-transfer reactions of bisiron(III) μ-oxo derivatives of DPX and DPD. The efficiency of the photochemical process is markedly dependent (∼104-fold) on the vertical flexibility of cofacial architecture provided by the spacer.
AB - A comparison of the structure, spectroscopy, and oxygen atom-transfer reactivity of cofacial bisporphyrins anchored by xanthene (DPX) and dibenzofuran (DPD) pillars is presented. The synthesis and characterization of dicopper(II) and dinickel(II) complexes of DPD completes a homologous series of homobimetallic zinc(II), copper(II), and nickel(II) complexes for both cofacial platforms. X-ray crystallographic analysis of the parent free-base porphyrins H4DPX (1) and H4DPD (5) confirms the face-to-face arrangement of the two porphyrin macrocycles with a large available range of vertical pocket sizes: 1 (C80H92Cl2N8O), triclinic, space group P, a = 13.5167(12) Å, b = 21.7008(18) Å, c = 23.808(2) Å, α = 80.116(2)°, β = 76.832(2)°, γ = 80.4070(10)°, Z = 4; 5 (C80H83N8O2), monoclinic, space group C2/c, a = 22.666(2) Å, b = 13.6749(14) Å, c = 42.084(4) Å, β = 94.554(2)°, Z = 8. EPR spectroscopy of dicopper(II) derivatives Cu2DPX (3) and Cu2DPD (7) complements the crystallographic studies by probing intramolecular metal-metal arrangements in frozen solution. Exciton interactions between the porphyrin subunits in fluid solution are revealed by steady-state and time-resolved electronic absorption and emission spectroscopy. The resulting compilation of structural and spectroscopic data provides a benchmark for the use of these and related platforms for the activation of small-molecule substrates. A structure-function relation is developed for the photoinduced oxygen atom-transfer reactions of bisiron(III) μ-oxo derivatives of DPX and DPD. The efficiency of the photochemical process is markedly dependent (∼104-fold) on the vertical flexibility of cofacial architecture provided by the spacer.
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U2 - 10.1021/ic0111029
DO - 10.1021/ic0111029
M3 - Article
C2 - 12054988
AN - SCOPUS:0037124233
SN - 0020-1669
VL - 41
SP - 3102
EP - 3109
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 12
ER -