  We report the crystal structure, superconductivity and normal state
properties of two iron-based materials, Li0.15(C3H10N2)0.32FeSe(P-4) and
Lix(C3H10N2)0.32FeSe(P4/nmm, 0.25<x<0.4) with superconducting transition
temperature from 40~46K. The determined crystal structures revealed a coupling
between Li concentration and the oritation of 1,2-Diaminopropane molecules
within the hyper expanded FeSe layers. Further fitting on resistivity in terms
of the Lawence-Doniach model suggests the two superconductors belong to the
quasi-two dimonsional system. With increasing temperature, a differences in
crystal structures and doping levels. First principle calculations revealed the
increase in FeSe layer diatance will restruct the Fermi surface and generate a
new hole pocket around Gamma point in the Brillouin Zone. Our findings support
that the increase in two dimensionalities will leads to a temperature induced
Lifshitz transition in electron doped FeSe superconductors.
