Spectroscopy and Electronic Structure of Electron Deficient Zinc Phthalocyanines

• Published in: Journal of the American Chemical Society Vol. 125; no. 23; pp. 7067 - 7085
• Main Authors: Keizer, Steven P, Mack, John, Bench, Barbara A, Gorun, Sergiu M, Stillman, Martin J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11-06-2003
• Subjects: Atomic and molecular physics; Exact sciences and technology; Molecular properties and interactions with photons; Optical activity and dichroism; magnetooptical and electrooptical spectra; Other magnetooptical and electrooptical effects; Physics; Magnetooptical properties; Frontier orbital; Nitrogen heterocycle; Electronically excited state; Organic ligand; Theoretical study; Electron charge distribution; Mass spectroscopy; Experimental study; Transition elements Complexes; Electronic structure; Molecular orbital method; Metallophthalocyanine; Density functional method; Magnetic circular dichroism; Zinc Complexes; EPR spectroscopy; Ultraviolet visible spectrometry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0299710

The effect of introduction of perfluoro alkyl groups into phthalocyanines, as evidenced by the spectroscopic properties of 1,4,8,11,15,18,22,25-octa-fluoro-2,3,9,10,16,17,23,24-octa-perfluoro isopropyl zinc phthalocyanine, ZnF64Pc(−2) and its ring-reduced radical anion species, [ZnF64Pc(−3)]-, are reported. A combination of UV−visible absorption and magnetic circular dichroism (MCD) spectroscopy, ESI and MALDI-TOF mass spectrometry, cyclic and differential pulse voltammetry, and complete theoretical calculations using INDO/S and DFT techniques reveals that the substitution of all sixteen hydrogen atoms in protio ZnPc(−2) by eight F and eight i-C3F7 groups red shifts the Q and π → π* transitions and narrows the HOMO−LUMO gap while simultaneously preventing ring photooxidation and stabilizing the radical anion. The [ZnF64Pc(−3)]- species, which is in equilibrium in solution with the neutral complex when a reducing agent is present, is unusually stable. The above effects are attributed to the strong electron withdrawing properties of the peripheral substituents, which render ZnF64Pc extremely electron deficient.