Nuclear magnetic resonance, electron paramagnetic resonance and magnetization measurements show that bulk ${\mathrm{Li}}_x\mathrm{ZnPc}$ are strongly correlated one-dimensional metals. The temperature dependence of the nuclear spin-lattice relaxation rate $1/T_1$ and of the static uniform susceptibility ${\chi }_S$ on approaching room temperature are characteristic of a Fermi liquid. Moreover, while for $x\simeq 2$ the electrons are delocalized down to low temperature, for $x\to 4$ a tendency towards localization is noticed upon cooling, yielding an increase both in $1/T_1$ and ${\chi }_s$. The $x$ dependence of the effective density of states at the Fermi level $D(E_F)$ displays a sharp enhancement for $x\simeq 2$, at the half filling of the ZnPc lowest unoccupied molecular orbitals. This suggests that ${\mathrm{Li}}_x\mathrm{ZnPc}$ is on the edge of a metal-insulator transition where enhanced superconducting fluctuations could develop

• Received 19 October 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.117601