Self-Assembled and Alternative Porphyrin-Phthalocyanine Array

An alternative molecular porphyrin-phthalocyanine aggregate was prepared and characterized with UV-visible and X-ray absorption spectroscopies. UV-visible experiments evidence 1-dimensional porphyrin-phthalo-cyanine array formed by mixing <TEX>SnTPPCl₂ (λₘₐₓ=429,\;ε=2.4×10^ 5 /M·cm)\;and\;NiPc(OBu)₈(λₘₐₓ=744 nm,\;ε= 2.0×10^ 5 /M·cm)</TEX> in solution. In the UV-visible spectrum of the porphyrin-phthalocyanine array, <TEX>(SnPNiPc)ₙ</TEX>, a new Q-band appeared at 844 nm with decrease of the Q-band peak of <TEX>NiPc(OBu)₈</TEX> at 744 nm. The red-shift of Q-band evidences an alternative porphyrin-phthalocyanine array formed in solution through metal-halide interaction rather than <TEX>π-π</TEX> facial interaction, in which nickel of <TEX>NiPc(OBu)₈</TEX> coordinates with chloride of <TEX>SnTPPCl₂</TEX> through self assembly. Ni K-edge XANES (X-ray absorption near edge structure) spectra also support the axial ligation of nickel to chloride. The square planar structure of <TEX>NiPc(OBu)₈</TEX> turns to an octahedral structure in (SnPNiPcSnP) by axial ligation. A higher energy-shift (0.2 eV) of the preedge peak of (SnPNiPcSnP) indicaties partial oxidation of nickel by charge transfer from NiPc<TEX>(OBu)₈</TEX> to SnTPPCl<TEX>₂</TEX>.