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Synthesis and Photophysical Properties of Silica‐Gel‐Supported Photofunctional (Phthalocyaninato)silicon Complexes
Author(s) -
Ishii Kazuyuki,
Kikukawa Yuu,
Shiine Masahiko,
Kobayashi Nagao,
Tsuru Tatsuro,
Sakai Yasuyuki,
Sakoda Akiyoshi
Publication year - 2008
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200800208
Subject(s) - chemistry , singlet oxygen , silica gel , luminescence , cyclohexane , photochemistry , adsorption , solvent , desorption , absorption (acoustics) , fluorescence , silicon , oxygen , organic chemistry , physics , optoelectronics , quantum mechanics , acoustics
Abstract The photophysical properties and surface structures of silica‐gel‐supported photofunctional (phthalocyaninato)silicon complexes (SiPc‐SiO 2 ) were investigated in terms of their electronic absorption, fluorescence, singlet‐oxygen luminescence, and nitrogen adsorption/desorption isotherms. Thenitrogen/desorption isotherms indicate that the planes of SiPcs Aanchored by axial ligands are parallel to the silica gel surface. In the proposed structure the tetradentate Pc ligands are considered to coordinate with the silica gel particles, since central elements of SiPcs, such as Si–O–Si–OH, are similar to constituents of silica gel. It was shown that the addition of an organic solvent (chloroform, cyclohexane, etc.), whose refractive index is comparable to that of the silica gels, increases the transparency of the silica gels. This method of adding the solvent allows to quantitatively analyze the photophysical properties and is useful for investigating other modified silicas. The intensities of fluorescence and singlet‐oxygen luminescence decrease with an increase in the amount of SiPcs due to interactions between the SiPcs in aggregates. By changing the amount of SiPcs, solid materials were prepared based on Pc complexes with both monomeric photophysical properties and a high ability for singlet‐oxygen generation. The electronic absorption spectra of SiPc‐SiO 2 indicate that a wide optical window is maintained between the Soret and Q absorption bands, even for high concentrations of SiPcs ([SiPc] ≈ 10 –2 M ). This results in deep‐green solids, which is unlike the blue color of the crystals or concentrated solutions (>10 –5 M ) of SiPc(OH) 2 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)