Unexpected Supramolecular-Induced Redox Switching in Sandwich Gd Bisphthalocyaninate.

The redox state of the phthalocyanine in sandwich lanthanide complexes is crucial for their applications. In this work, we demonstrate that the cation-induced supramolecular assembly of crown-substituted phthalocyanine lanthanide complexes Ln[(15C5)4Pc]2 can be used to control the redox state of the ligand simultaneously with the coordination sphere of the central metal. We achieve unprecedented redox switching of phthalocyanine ligands in a double-decker Gd(III) complex, resulting from the intramolecular inclusion of potassium cations between the decks with simultaneous twisting of the ligands (the skew angle between them decreases from 44.61 to 0.21°). Such a structural change leads to an increase in the deck-to-deck distance and drastically facilitates ligand reduction. This process was shown to be anion-dependent: only potassium salts of weak acids (KOPiv and KOAc) induce intramolecular inclusion of cations with redox switching in contrast to salts of strong acids (KBr, KOPic, KSCN, and KPF6), where such a redox process does not occur. This breakthrough opens new avenues for controlling the electrochromic properties, of phthalocyanines, along with other properties, such as electrical conductivity, optics, etc.

Cation-Induced Dimerization of Crown-Substituted Gallium Phthalocyanine by Complexing with Alkali Metals: The Crucial Role of a Central Metal.

The single-crystal X-ray diffraction characterization of cation-induced supramolecular assembly of the gallium(III) tetra(15-crown-5)phthalocyaninate [(HO)Ga(15C5)4Pc] (1Ga) is reported. The structures of two crystalline dimers, {[(1Ga)2Rb4]4+(iNic-)4}·10CDCl3 and {[(2Ga)2Rb4]4+(OH-)2(Piv-)2}·16CDCl3 (2Ga-[(Piv)Ga(15C5)4Pc]), as well as UV-vis and NMR studies of the soluble supramolecular dimers formed by 1Ga and K+, Rb+, and Cs+ salts are provided. In contrast to the previously reported aluminum complex where the Al-O-Al bond was formed, no µ-oxo bridge was observed between the gallium atoms in the supramolecular dimers under similar conditions, despite the fact that aluminum and gallium belong to the same group of the periodic table. The detailed investigation of the cation-induced dimers of 1Ga confirms the uniformity of their structure for all large alkali cations, where two molecules of crown-substituted gallium phthalocyaninate are 4-fold bound by K+, Rb+, or Cs+. The gallium(III) coordination sphere is labile, and the nature of the solvent during supramolecular dimerization has an effect on the axial ligand exchange: Piv- in nonpolar CHCl3 replaces the initial OH- in 1Ga, while such a process is not observed in CHCl3/CH3OH media.

Cation-Induced Dimerization of Crown-Substituted Phthalocyanines by Complexation with Rubidium Nicotinate As Revealed by X-ray Structural Data.

The supramolecular dimeric complex [(µ-oxo)bis(tetra-15-crown-5-phthalocyaninato)(nicotinato)aluminum(III)]tetra(rubidium) bis(nicotinate) was prepared by addition of an excess of a methanol solution of rubidium nicotinate to a chloroform solution of the aluminum crown-phthalocyaninate, [(HO)Al(15C5)4Pc]. A single-crystal X-ray diffraction study of {[Rb4(NicAl(15C5)4Pc)2(µ-O)]2+(Nic-)2}·2.36HNic·11H2O demonstrated that two molecules of the aluminum crown-phthalocyaninate nicotinate are connected through an Al-O-Al bridge supported by sandwiching of crown ether moieties by Rb+ cations.