•A reaction between [Fe(qsal)2]+ and CA2– yielded an ionic salt [FeIII(qsal)2]+[FeIII(CA)(qsal)Cl]–.•Each cationic and anionic unit is self assembled through intermolecular π–π stacking interactions in the crystal lattice.•Both FeIII ions were in HS spin states over the whole temperature region.A new hybrid molecular salt [FeIII(qsal)2][FeIII(CA)(qsal)Cl]·MeNO2 (1), where qsal– = N-(8-quinolyl)salicylaldiminate and CA2– = chloranilate was synthesized and structurally characterized by single-crystal X-ray crystallography. Each cationic [FeIII(qsal)2]+ and anionic [FeIII(CA)(qsal)Cl]– unit is self assembled through intermolecular π–π stacking interactions between qsal– ligands, which stabilize the supramolecular networks in the crystal lattice. Magnetic measurements for 1 revealed that both FeIII ions were in HS spin states with a small contribution from ZFS over the whole temperature region.

The proton conducting properties of two different structural types of porous coordination polymers [La2(ox)3(H2O)6]·4H2O (1) and [Er2(ox)3(H2O)6]·12H2O (2), where ox2− = oxalate, were investigated. 1 has a two-dimensional layered structure, whereas 2 has a three-dimensional structure. Both 1 and 2 have hydrophilic one-dimensional channels filled by lattice water molecules with hydrogen-bonding networks. The coordinated H2O molecules are Lewis acidic due to the lanthanoid ions donating protons to lattice-filling H2O molecules, thereby forming efficient proton conduction pathways. Alternating-current impedance analyses of 1 and 2 indicated significant proton conduction (σ = 3.35 × 10−7 S cm−1 at 368 K for 1, 1.79 × 10−6 S cm−1 at 363 K for 2 under RH = 100%, with Ea = 0.35 eV for 1 and 0.47 eV for 2), which was attributed to the Grotthuss mechanism via the lattice H2O molecules.