Semiconductive tetrahedral M4L4 coordination cages (M = Ni2+ and Co2+) constructed by a rigid conjugated tris(N,N-chelate) tripod

Two semiconductive isostructural M4L4 tetrahedral coordination cages, 1 and 2, have been constructed from a C3-symmetric tris(bidentate) chelator L and pseudo-octahedral metal ions (1; M = Ni2+; 2: M = Co2+). The M4L4 framework of 1 has been structurally determined, which exhibits homochiral (Δ, P)-configuration. Besides, spontaneous resolution is observed during their crystallization, which is ascertained by the appearance of cotton effect in their CD (Circular Dichroism) spectra. Variable-temperature magnetic susceptibility measurements have been conducted to get some insights into spin-interactions of metal ions in 1 and 2. Diffuse-reflectance UV–vis spectroscopy manifest that 1 and 2 exhibit lower optical band gap compared to L ligand. Complex impedance spectroscopy shows that 1 and 2 have the conductivity of about 1.48 × 10−8 S cm−1 and 1.91 × 10−9 S cm−1 at 30 °C, respectively.