Electronic properties of the charge transfer material MnPc/F4TCNQ

An unusual donor-acceptor system MnIIPc-TCNQ/F4-TCNQ and the properties of the mixed single crystals of metal phthalocyanines with organic acceptor molecules

The interaction of manganese(ii) phthalocyanine with 7,7,8,8-tetracyanoquinodimethane and its perfluoro derivative proceeds with the oxidation of Mn and the reduction of the acceptor molecules to give the first mixed single crystals of manganese(iii) phthalocyanine with TCNQ/F4-TCNQ radical anions. The crystals have unusual structures with C-Hπ interactions between the ions and their orthogonal arrangement, as well as remarkable redox properties. The charge transfer was proved by spectroscopic and magnetic studies.

Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces

Manganese phthalocyanine (MnPc) is a member of the family of transition-metal phthalocyanines, which combines interesting electronic behavior in the fields of organic and molecular electronics with local magnetic moments. MnPc is characterized by hybrid states between the Mn 3d orbitals and the π orbitals of the ligand very close to the Fermi level. This causes particular physical properties, different from those of the other phthalocyanines, such as a rather small ionization potential, a small band gap and a large electron affinity. These can be exploited to prepare particular compounds and interfaces with appropriate partners, which are characterized by a charge transfer from or to MnPc. We summarize recent spectroscopic and theoretical results that have been achieved in this regard.

Formation of ferromagnetic molecular thin films from blends by annealing

We report on a new approach for the fabrication of ferromagnetic molecular thin films. Co-evaporated films of manganese phthalocyanine (MnPc) and tetracyanoquinodimethane (TCNQ) have been produced by organic molecular beam deposition (OMBD) on rigid (glass, silicon) and flexible (Kapton) substrates kept at room temperature. The MnPc:TCNQ films are found to be entirely amorphous due to the size mismatch of the molecules. However, by annealing while covering the samples highly crystalline MnPc films in the β-polymorph can be obtained at 60 °C lower than when starting with pure MnPc films. The resulting films exhibit substantial coercivity (13 mT) at 2 K and a Curie temperature of 11.5 K.