Two one-dimensional germanium(IV) coordination polymers based on macrocyclic tetraaza[14]annulene with notable semiconducting property

Two one-dimensional (1D) germanium(IV) coordination polymers (CPs) containing macrocyclic tetraaza[14]annulene, [Ge(tmtaa)(L)]_n [tmtaa = tetraaza[14]annulene, L = 1,4-benezedicarboxylate 1; 2,5-dihydroxyl-1,4- benezedicarboxylate, 2], are synthesized and characterized. The temperature dependence of the electrical conductivity (σ) for 1 or 2 indicates region of rising dσ/dT (the conductivity increases with increasing temperature), suggesting semiconductor-like charge transport in the stacking direction. The room temperature electrical conductivities for 1 and 2 are 1.52 × 10 ^{- 8} S cm^{- 1} and 1.18 × 10^{- 5} S cm ^{- 1}, respectively, which are obviously higher than those of most 1D metallophthalocyanine- and metalloporphyrine-containing CPs. Though the crystal structures of 1 and 2 are similar, 2 exhibits better electrical conductivity which is about three orders higher than that of 1. This may be due to the protonic conduction existing in 2. Furthermore, 1 and 2 show outstanding thermal stability. These results suggest the potential applications of 1 and 2 as semiconductive materials.