RESUMO
Two single molecule magnets based on the dodecamanganese (III, IV) cluster with either benzoate or terphenyl-4-carboxylate ligands, have been studied on the Au(111) and rutile TiO2(110) surfaces. We have used in situ electrospray deposition to produce a series of surface coverages from a fraction of a monolayer to multilayer films in both cases. X-ray absorption spectroscopy measured at the Mn L-edge (Mn 2p) has been used to study the effect of adsorption on the oxidation states of the manganese atoms in the core. In the case of the benzoate-functionalised complex reduction of the manganese metal centres is observed due to the interaction of the manganese core with the underlying surface. In the case of terphenyl-4-carboxylate, the presence of this much larger ligand prevents the magnetic core from interacting with either the gold or the titanium dioxide surfaces and the characteristic Mn(3+) and Mn(4+) oxidation states necessary for magnetic behaviour are preserved.
RESUMO
Five new metal-organic frameworks prepared from the ligand 5-bis(3-(1-imidazolyl)propylcarbamoyl)terephthalate (bipta(2-)) and transition metal salts, Zn(2+) (1), Co(2+) (2), Mn(2+) (3, 4) and Cu(2+) (5), are reported. Single crystal X-ray studies reveal that the bipta(2-) ligand acts as a tetradentate ligand and combines with four-coordinate cationic metal nodes to give four-connected framework structures. Whilst reaction of bipta(2-) with Zn(II) gives rise to a framework of diamondoid topology 1, the analogous frameworks with Co(II), Mn(II) and Cu(II) afford frameworks that incorporate square-planar nodes. Whereas 2 and 5 form frameworks of Cd(SO(4)) (cds) and square 4(4) nets (sql), respectively, reaction of Mn(II) with bipta(2-) forms two supramolecular isomers of topology cds for 3 and sql for 4.
RESUMO
The redox processes associated with BODIPY analogues are studied by electrochemical and spectroscopic methods revealing a characteristic profile for the persistent BODIPY radical and quenching of fluorescence upon reduction.
RESUMO
The synthesis, structural and magnetic characterisation of trinuclear manganese cluster, [Mn(3)O(O(2)C-anth)(6)(HOCH(3))(3)] 1 (where O(2)C-anth = 9-anthracenecarboxylate), with crystallographic three-fold (C(3)) symmetry, are described. The cluster was prepared by a carboxylate exchange reaction between HO(2)C-anth and [Mn(12)O(12)(O(2)CMe)(16)(H(2)O)(4)] with concomitant fragmentation of the dodecanuclear Mn core of the starting material to form a trinuclear Mn(3)(µ(3)-O) cluster capped by six carboxylate ligands. Bond valence sum calculations and SQUID magnetometric measurements establish the oxidation states of the metal ions as Mn(II)·2 Mn(III) which are antiferromagnetically coupled.