Intrinsic Semiconducting Materials on Phthalocyanine Basis

Authors: Michael HANACK

Abstract: Stacked transition metal macrocycles [MacM(L)]$_n$ with M e.g. Fe, Ru, Os, Co, Rh and Mac = phthalocyanine (Pc) 1,2- or 2,3-naphthalocyanine (1,2-, 2,3-Nc) were synthesized. The bridging ligands (L) may be e.g. pyrazine (pyz) or $s$-tetrazine (tz). In general, these complexes [MacM(L)]$_n$ are insoluble in organic solvents; however, soluble oligomers [R$_4$PcM(L)]$_n$ can be prepared using metallomacrocycles R$_n$PcM, R = $t$-bu, et, OR, M = Fe, Ru, which are substituted in the peripheric positions. A systematic investigation of the influence of the bridging ligands on the semiconducting properties in [MacM(L)]$_n$ reveals that changing L, e.g., from dabco over pyz to tz leads to a steady increase of the semiconducting properties without external oxidative doping. Powder conductivities in the order of 0.1 S/cm can be reached by using $s$-tetrazine, 3,6-dimethyl-$s$-tetrazine (me$_2$tz) and others, e.g. fumarodinitrile, as the bridging ligands. The intrinsic conductivities are a result of the low oxidation potential of tz and me$_2$tz and due to the low lying LUMO in the corresponding bridged systems [MacM(tz)]$_n$.


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