Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

Abstract

To avoid the use of hydrofluoric acid, a series of fluorinated trivalent and tetravalent metal-containing phthalocyanines (MPcs) were synthesized using a straightforward one-step halide substitution process using cesium fluoride (CsF) as the fluoride source and by reflux in N , N -dimethylformamide for less than an hour. The resulting fluoro MPcs were characterized and compared to the parent chloro MPcs. In some cases, very little change in properties was observed between the fluoro MPcs and the chloro MPcs. In other cases, such as fluoro aluminum phthalocyanine, a blue shift in the absorbance characteristics and an increase in oxidation and reduction potential of as much as 0.22 V was observed compared to the chloro derivative. Thermo gravimetric analysis was performed on all halo-MPcs, indicating that the choice of halo substitution on the axial position can have an effect on the decomposition or sublimation temperature of the final compound. After initial establishment and characterization of the fluoro MPcs, the halide substitution reaction of difluoro silicon phthalocyanine (F 2 -SiPc) was further explored by scaling the reaction up to a gram scale as well as considering tetrabutylammonium fluoride (TBAF) as an additional safe fluoride source. The scaled-up reactions producing F 2 -SiPc using CsF and TBAF as fluoride exchange sources were successfully reproducible, resulting in reaction yields of 100 and 73%, respectively. Both processes led to pure final products but results indicate that CsF, as the fluoride exchange reagent, appears to be the superior reaction process as it has a much higher yield.

Metal phthalocyanines: thin-film formation, microstructure, and physical properties

“…14iii). 149,150 In the low energy region of the B band (around 288 nm) changes to the absorption spectra between MPcs is thought to be due to orbital overlap of the phthalocyanine ring and the central metal. 146,147 The high intensity peak in the low energy B band region exhibited in CuPc, CoPc, FePc, and nickel phthalocyanine (NiPc) suggests dband association with the central metal, arising to p-d transitions as a result of the partially occupied d-orbitals of these metals.…”

Silicon phthalocyanines: synthesis and resurgent applications

“…27,28 Recently, Bender and coworkers synthesized SiPcF2 by refluxing 1 with either cesium fluoride (CsF) in dimethylformamide or with tetrabutylammonium fluoride in dimethyl sulfoxide. 29 These alternate strategies involved relatively safer fluorinating agents compared to HF and resulted in high reaction yields of 100% and 73% respectively. In a similar approach, boron tribromide was used as a brominating reagent for the synthesis of SiPcBr2.…”

Electrochemical and spectroelectrochemical studies of tert-butyl-substituted aluminum phthalocyanine

“…The electrochemical behavior of aluminum Pcs in the oxidation region and in non-coordinating solvents was poorly represented in the literature. However, voltammetric behavior of PcAlCl in a non-coordinating solvent CH2Cl2 [21] showed irreversibility of the first oxidation and first two reduction transitions with the first oxidation peak at a potential shifted by ca. 0.45 V from the value in THF and DMF, which is rather high.…”