Near-Infrared-Emitting Phthalocyanines. A Combined Experimental and Density Functional Theory Study of the Structural, Optical, and Photophysical Properties of Pd(II) and Pt(II) 伪-Butoxyphthalocyanine

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• 作者：Alexandra V. Soldatova ; Junhwan Kim ; Corrado Rizzoli ; Malcolm E. Kenney ; Michael A. J. Rodgers ; Angela Rosa ; Giampaolo Ricciardi
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：February 7, 2011
• 年：2011
• 卷：50
• 期：3
• 页码：1135-1149
• 全文大小：1281K
• 年卷期：v.50,no.3(February 7, 2011)
• ISSN：1520-510X

文摘

The structural, optical, and photophysical properties of 1,4,8,11,15,18,22,25-octabutoxyphthalocyaninato-palladium(II), PdPc(OBu)₈, and the newly synthesized platinum analogue PtPc(OBu)₈ are investigated combining X-ray crystallography, static and transient absorption spectroscopy, and relativistic zeroth-order regular approximation (ZORA) Density Functional Theory (DFT)/Time Dependent DFT (TDDFT) calculations where spin鈭抩rbit coupling (SOC) effects are explicitly considered. The results are compared to those previously reported for NiPc(OBu)₈ (J. Phys. Chem. A 2005, 109, 2078) in an effort to highlight the effect of the central metal on the structural and photophysical properties of the group 10 transition metal octabutoxyphthalocyanines. Different from the nickel analogue, PdPc(OBu)₈ and PtPc(OBu)₈ show a modest and irregular saddling distortion of the macrocycle, but share with the first member of the group similar UV鈭抳is spectra, with the deep red and intense Q-band absorption experiencing a blue shift down the group, as observed in virtually all tetrapyrrolic complexes of this triad. The blue shift of the Q-band along the MPc(OBu)₈ (M = Ni, Pd, Pt) series is interpreted on the basis of the metal-induced electronic structure changes. Besides the intense deep red absorption, the title complexes exhibit a distinct near-infrared (NIR) absorption due to a transition to the double-group 1E (蟺,蟺*) state, which is dominated by the lowest single-group ³E (蟺,蟺*) state. Unlike NiPc(OBu)₈, which is nonluminescent, PdPc(OBu)₈ and PtPc(OBu)₈ show both deep red fluorescence emission and NIR phosphorescence emission. Transient absorption experiments and relativistic spin鈭抩rbit TDDFT calculations consistently indicate that fluorescence and phosphorescence emissions occur from the S₁(蟺,蟺*) and T₁(蟺,蟺*) states, respectively, the latter being directly populated from the former, and the triplet state decays directly to the S₀ surface (the triplet lifetime in deaerated benzene solution was 3.04 渭s for Pd and 0.55 渭s for Pt). Owing to their triplet properties, PdPc(OBu)₈ and PtPc(OBu)₈ have potential for use in photodynamic therapy (PDT) and are potential candidates for NIR light emitting diodes or NIR emitting probes.