The high temperature magnetic and structural properties of an amphiphilic iron(III) spin crossover complex are reported. Thermal cycling reveals a scan rate-dependent 20 K thermal hysteresis in the _mT vs. T data close to room temperature. A fast scan rate is essential for the hysteresis but it is robust and reproducible after multiple thermal cycles. Differential scanning calorimetry and cross polarized microscopy are used to show that the magnetic switching aligns with a material state change from solid to ordered liquid phase on warming.

The two-step spin crossover in mononuclear iron(III) complex [Fe(salpm)₂]ClO₄⋅0.5 EtOH (1) is shown to be accompanied by a structural phase transition as concluded from ⁵⁷Fe Mössbauer spectroscopy and single crystal X-ray diffraction, with spin-state ordering on just one of two sub-lattices in the intermediate magnetic and structural phase. The complex also exhibits thermal- and light-induced spin-state trapping (TIESST and LIESST), and relaxation from the LIESST and TIESST excited states occurs via the broken symmetry intermediate phase. Two relaxation events are evident in both experiments, that is, two T(LIESST) and two T(TIESST) values are recorded. The change in symmetry which accompanies the TIESST effect was followed in real time using single crystal diffraction. After flash freezing at 15 K the crystal was warmed to 40 K at which temperature superstructure reflections were observed to appear and disappear within a 10 000 s time range. In the frame of the international year of crystallography, these results illustrate how X-ray diffraction makes it possible to understand complex ordering phenomena.

Six solvated salts of a mononuclear manganese(III) complex with a chelating hexadentate Schiff base ligand are reported. One member of the series, [MnL]PF₆^.0.5 CH₃OH (1), shows a rare low-spin (LS) electronic configuration between 10–300 K. The remaining five salts, [MnL]NO₃⋅ C₂H₅OH (2), [MnL]BF₄⋅C₂H₅OH (3), [MnL]CF₃SO₃⋅C₂H₅OH (4), [MnL]ClO₄⋅C₂H₅OH (5) and [MnL]ClO₄⋅0.5 CH₃CN (6), all show gradual incomplete spin-crossover (SCO) behaviour. The structures of all were determined at 100 K, and also at 293 K in the case of 3–6. The LS salt [MnL]PF₆^.0.5 CH₃OH is the only member of the series that does not exhibit strong hydrogen bonding. At 100 K two of the four SCO complexes (2 and 4) assemble into 1D hydrogen-bonded chains, which weaken or rupture on warming. The remaining SCO complexes 3, 5 and 6 do not form 1D hydrogen-bonded chains, but instead exhibit discrete hydrogen bonding between cation/counterion, cation/solvent or counterion/solvent and show no significant change on warming.

Eight new para-quinones and one known analogue have been synthesized from p-chloranil. Five have been structurally characterized by single crystal diffraction, and a range of ligand folding is observed. All nine have been tested for their potency towards Gram(+) S. aureus and Gram(−) E. coli. Quinones 3, 6, 7 and 8 have shown activity towards S. aureus and quinones 3 and 8 also show good activity towards E. coli.

Thermal spin crossover (SCO) was induced in a high-spin Fe^III complex by alkylation of the polyamino ligand backbone. The SCO profile was responsive to chain length with partial crossover observed with C₆ alkylation and full transition upon lengthening to C₁₂. No crossover was observed when the backbone was unfunctionalised, and all three complexes were obtained as unsolvated tetrafluoroborate salts.