Spectroscopy and Electronic Structure of Electron Deficient Zinc Phthalocyanines

Abstract

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, ZnF(64)Pc(-2) and its ring-reduced radical anion species, [ZnF(64)Pc(-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-C(3)F(7) groups red shifts the Q and pi --> pi transitions and narrows the HOMO-LUMO gap while simultaneously preventing ring photooxidation and stabilizing the radical anion. The [ZnF(64)Pc(-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 ZnF(64)Pc extremely electron deficient.

Characterisation of Langmuir–Blodgett films of new multinuclear copper and zinc phthalocyanines and their sensing properties to volatile organic vapours

“…A similar argument applies to the Q band splitting observed in the absorption spectrum of CuPc solution. The Q band for both samples are associated with the → * transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) of the phthalocyanine ring [27]. The B bands of these materials are arising from deeper levels → LUMO transitions, which are occurring in the UV region between 300 and 400 nm [28].…”

Structural modifications of zinc phthalocyanine thin films for organic photovoltaic applications

“…13,14 As one of the most promising OPV materials, metal phthalocynine including zinc phthalocyanine (ZnPc) is attracting continual interests due to its high absorption coefficient and good chemical and thermal stability. 15 The growth characteristics of evaporated phthalocynine films have been experimentally and theoretically investigated. In most of literatures, phthalocynine films were prepared on clean substrates such as the single-crystal substrate and glass.…”

Growth and characterization of thin films prepared from perfluoro-isopropyl-substituted perfluorophthalocyanines

“…This effect was indicated for a number of phthalocyanines, including those bearing F-groups, by quantum chemical calculations of isolated molecules [20][21][22][23][24], by the observed shifts of the electrochemical potential of molecules in solution [25] and by shifts of the ionization energy obtained by photoelectron spectroscopy for molecules in the gas phase [26]. An easy reduction of phthalocyanines can lead to technically interesting n-type conduction.…”