Structures and Redox Characteristics of Electron-Deficient Vanadyl Phthalocyanines

Abstract

The first single-crystal X-ray structures of substituted vanadyl phthalocyanine materials reveal the high-valence vanadium ions (denoted as V(IV)), whose coordination by a highly electron-deficient ligand is facilitated by an axial oxo group. The metal center of the hydrophilic V═O core, encapsulated in F-rich hydrophobic pockets, reaches a coordination number of 6 by binding an additional H(2)O that, in turn, hydrogen-bonds with ketones, resulting in solvent-induced variable solid-state architectures. Fluoroalkyl (R(f)) ligand substituents hinder π-π stacking interactions and favor ordered long-range packing, as well as the facile formation of film materials that exhibit high thermal stability and oxidation resistance. Reversible redox chemistry and spectroscopic studies in both solution and the solid-state indicate single-site isolation in both phases and an R(f)-induced propensity for electron uptake and inhibition of electron loss. Repeated redox cycles reorganize the thin films to accommodate Li(+) ions and facilitate their migration. The facile reduction, combined with high stability and ease of sublimation imparted by the R(f) scaffold that suppresses oxidations, recommends the new materials for sensors, color displays, electronic materials, and redox catalysts, as well as other applications.

Electrochromic Switching of Evaporated Thin Films of Bulky, Electronic Deficient Metallo-Phthalocyanines

“…We compare their characteristics with those of F 64 PcVO which we studied separately. 31 The effects of the R f groups are revealed by comparison with perfluorinated F 16 PcCu 2 similar to the earlier studied F 16 PcZn. 20 ' MATERIALS AND METHODS F 64 PcCu and F 64 PcZn were synthesized and purified as reported earlier.…”

“…33 We found characteristics quite similar to those independently reported for F 64 PcVO in solution. 31 As a best estimate for the position of the redox potentials of the subsequent reduction steps, the average was calculated between the respective reduction and reoxidation waves of the wave pairs and referred to the SCE potential (Table 1). Quite similar potentials were determined for the F 64 PcCu and F 64 PcZn complexes, only slightly less negative than those reported for (Cl À )F 64 PcZn and slightly more negative than those found for F 64 PcVO.…”

“…31 A thinner film (40 nm) of F 64 PcCu was prepared and studied at a slower scan rate (0.05 V s À1 ) in order to reveal in greater detail the kinetics of the electrochromic reduction and reoxidation reactions. The thinner films showed slightly different absorbance spectra (Figure 6a, initial spectrum) when compared with the thicker films, Figure 4.…”

Synthesis and EPR studies of soluble vanadyl octakis(4-tert-butylbenzylthio) porphyrazine

“…The 1,2-bis-(4-t-butylbenzylthio)maleonitrile (TBBTMNT), octakis(4-tert-butylbenzylthio) porphyrazinato magnesium(II) (MgPz), and metal-free octakis(4-tert-butylbenzylthio) 21 H, 23 H porphyrazine (H 2 Pz) were prepared according to previously reported procedures with minor changes and characterized by comparing their spectral data to those reported earlier [13]. Mg(II) complex and metal-free porphyrazine were stable at room temperature and they were non-hygroscopic and insoluble in water but soluble in many common organic solvents.…”

“…The V-O axis in VOPc is located perpendicular to the plane of the molecule [23], leading the vanadyl oxygen to "stick out" of the overall molecular plane [24]. VOPc is known to be a dye with high thermal and chemical stabilities, large third-order nonlinear optical susceptibility [25], ultra-fast optical response, and good stability against visible light irradiation [26].…”