Three manganese(III) compounds, [Mn^III(vanoph)(DMF)(H₂O)]ClO₄ (1), [Mn^III(vanoph)(N₃)(H₂O)]·2H₂O (2) and [Mn^III(saloph)(μ_1,3-N₃)]_n (3), where H₂vanoph = N,N′-(1,2-phenylene)-bis(3-methoxysalicylideneimine), H₂saloph = N,N′-(1,2-phenylene)-bis(salicylideneamine) are tetradentate N₂O₂ ligands and DMF = N,N-dimethylformamide, have been prepared and characterised by elemental analysis, IR and UV–Vis spectroscopy and single-crystal X-ray diffraction studies. Compounds 1 and 2 are monomeric but compound 3 consists of a chain system with the repeating unit [Mn^III(saloph)(N₃)] bridged by μ-1,3 azide. Compound 1 crystallises in monoclinic space groupP2₁/n with cell dimensions of a = 11.1430(2), b = 16.3594(3), c = 15.4001(3) Å, β = 108.417(1), Z = 4 whereas compounds 2 and 3 crystallise in orthorhombic space groupsPbca and Pna2₁, respectively, with cell dimensions of a = 16.069(3), b = 15.616(3), c = 18.099(4) Å, Z = 8 (for 2) and a = 18.760(9), b = 13.356(5), c = 6.616(3) Å, Z = 4 (for 3). In all the compounds, Mn(III) has a six-coordinated pseudo-octahedral geometry in which O(2), O(3), N(1) and N(2) atoms of the deprotonated di-Schiff base constitute the equatorial plane. In both compounds 1 and 2, water molecules are present in the fifth coordination sites in the apical positions. The sixth coordination sites are occupied by one O atom of a solvent DMF in compound 1 and an N atom of azide in compound 2. The coordinated water initiates hydrogen-bonded networks in both compounds 1 and 2 to form well-isolated supramolecular dimers. At room temperature the χ_MT values for the compounds 1 and 2 remain almost constant until 30 K. Below this temperature, the χ_MT values drastically drop to 0.72 cm³ mol⁻¹ K for 1 and 0.52 cm³ mol⁻¹ K for 2. The best fits were obtained with J = −0.92 cm⁻¹, |D| = 2.05 cm⁻¹, g = 2.0 and R = 8.1 × 10⁻⁴ for 1 and J = −1.16 cm⁻¹, |D| = 2.05 cm⁻¹, g = 2.0 and R = 1.2 × 10⁻³ for 2. However, in compound 3, two axial positions are occupied by the azide ions. The Mn⋯Mn repeating distance is 6.616 Å along the chain. Magnetic characterisation shows that the μ_1,3-bridging azide ion mainly transmits an antiferromagnetic interaction (J = −6.36 cm⁻¹) between Mn(III) ions. The presence of two methoxy groups increases the steric crowding in the H₂vanoph moiety and thereby inhibits the formation of a polynuclear compound with this ligand.

Graphene electrodes are promising candidates to improve reproducibility and stability in molecular electronics through new electrode–molecule anchoring strategies. Here we report sequential electron transport in few-layer graphene transistors containing individual curcuminoid-based molecules anchored to the electrodes via π–π orbital bonding. We show the coexistence of inelastic co-tunneling excitations with single-electron transport physics due to an intermediate molecule–electrode coupling; we argue that an intermediate electron–phonon coupling is the origin of these vibrational-assisted excitations. These experimental observations are complemented with density functional theory calculations to model electron transport and the interaction between electrons and vibrational modes of the curcuminoid molecule. We find that the calculated vibrational modes of the molecule are in agreement with the experimentally observed excitations.

Two related single-molecule magnets, [Co(9Accm) ₂ (py) ₂ ] and [Co(9Accm) ₂ (2,2′-bpy)], with cis and trans disposition of the CCMoid ligands were studied in solution, in the solid state and by deposition on different surfaces.