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Multifunctional molecular ferroelectrics are exciting materials synthesized using molecular chemistry concepts, which may combine a spontaneous electrical polarization, switched upon applying an electric field, with another physical property. A high-temperature ferroelectric material is presented that is based on a chiral Zn(2+) /Dy(3+) complex exhibiting Dy(3+) luminescence, optical activity, and magnetism. We investigate the correlations between the electric polarization and the crystal structure as well as between the low-temperature magnetic slow relaxation and the optical properties.

The phenomenon of spin crossover (SCO) between high-spin (HS) and low-spin (LS) states of 3d 4 -3d 7 transition-metal complexes has attracted much interest.[1] Although the origin of the spin-crossover phenomenon is purely molecular, the macroscopic behavior of these systems in the solid state is strongly influenced by short-and long-range interactions (of mainly elastic origin) between the transition-metal ions, giving rise to remarkable cooperative phenomena, such as first-order phase transitions.[2] One of the most interesting open questions in this research field concerns the effect of size reduction on the cooperativity and on the relevant physical properties. Notably, the hysteresis, which in certain cases accompanies the thermal spin transition, is considered to be an important property, as it confers a memory effect on these systems. As was suggested by Kahn and Martinez, [3] this phenomenon might be used for information storage. The same authors have estimated from statistical considerations that approximately 10 3 strongly interacting metal ions (i.e. comprising a particle with a diameter of a few nanometers) should be the approximate lower size limit for which an SCO solid might still exhibit hysteresis. The size dependence of the hysteresis width has also been investigated by Kawamoto and Abe on a model system taking into account only short-range interactions, [4] but the complexity of the elastic interactions in real systems and the poor knowledge of the relevant lattice properties (and their size dependence) makes it very difficult to reliably predict the interaction energies and hence the hysteresis width.To our knowledge, the first results concerning the sizereduction effect in SCO systems was reported by LØtard et al. [5,6] [7] At the same time, some of us reported an alternative method for the fabrication of nanoobjects (down to 30 nm) exhibiting SCO properties based on the lithographic patterning of thin films. [8,9] Such ordered arrays of SCO micro-and nanostructures are particularly interesting for potential applications of this phenomenon, but in the sub-micrometer range it is rather challenging to characterize their structure and physical properties, owing to the small signals. Moreover, it is difficult to obtain nanoobjects with sizes below 10 nm by means of lithographic techniques. This range is, however, accessible by chemical methods, which have the further advantage of allowing the synthesis of a large number of particles, and thus their physical characterization becomes feasible by standard averaging techniques, such as magnetometry.Herein, we report the synthesis and study of ultra-small monodisperse nanoparticles of the 3D spin crossover coordination polymer [Fe(pyrazine){Ni(CN) 4 }], [10] obtained using the biopolymer chitosan as matrix. It should be noted that investigations on the synthesis of cyano-bridged coordination polymers at the nanoscale level have attracted a great deal of attention in recent years, and numerous methods have been reported, including the use of reverse m...

The structures of neutral and ionic 4-cyanophenylpalladium() and methylpalladium() complexes containing bidentate phosphine ligands were investigated in solution and in the solid state. Diphosphine ligands with a xanthene and a ferrocene backbone were used. New bis(dialkylphosphino) substituted Xantphos ligands were synthesised. 1 H NMR and31 P NMR spectroscopy, conductivity measurements, UV-Vis spectroscopy, and X-ray crystallography were used to elucidate the structures of the complexes. Subtle changes of the phosphine ligands govern the coordination mode of the ligand. A variety of bidentate cis-, and trans-coordination and terdentate P-O-P, P-S-P and P-Fe-P coordination modes of the ligands were observed.

A new heterodinuclear [Zn(L)Dy](3+) complex, with L being a compartmental Schiff base ligand, exhibits the characteristic Dy(3+) luminescence associated with a single-ion field induced slow relaxation of the magnetisation. This complex may be considered as one of the rare examples of a bifunctional luminescent single-ion magnet.

We analyzed the size effect on a first-order spin transition governed by elastic interactions. This study was performed in the framework of a nonextensive thermodynamic core-shell model. When decreasing the particle size, differences in surface energies between the two phases lead to the shrinking of the thermal hysteresis width, the lowering of the transition temperature, and the increase of residual fractions at low temperature, in good agreement with recent experimental observations on spin transition nanomaterials. On the other hand, a modification of the particle-matrix interface may allow for the existence of the hysteresis loop even at very low sizes. In addition, an unexpected reopening of the hysteresis, when the size decreases, is also possible due to the hardening of the nanoparticles at very small sizes, which we deduced from the size dependence of the Debye temperature of a series of coordination nanoparticles.

The carbonic anhydrases (CAs, EC 4.2.1.1) are ubiquitous metalloenzymes with five independently evolved (R, ,γ,δ,ς) classes reported up to date. [1][2][3] These enzymes catalyze the reversible hydration of carbon dioxide to bicarbonate and protons by means of a metalhydroxide (Lig 3 M 2+ (OH) -) mechanism. 2 In addition to the established role of the carbonic anhydrase inhibitors (CAIs) as diuretics and antiglaucoma drugs, it has recently emerged that CAIs could have potential as novel antiobesity, anticancer, and anti-infective drugs. 1,2 A critical problem in the design of CAIs is related to the high number of isoforms in mammals (15), their diffuse localization in many tissues/organs, and the lack of isozyme selectivity of the presently available inhibitors. [1][2][3][4] Recently, nanoparticles received great attention for their biomedical applications both for the site-specific delivery of drugs 7 or for imaging purposes. 7,8 Several recent such examples include HIV inhibition with a CCR5 antagonist attached to multivalent gold nanoparticles (Au NPs), tumor targeting with NPs loaded with hydroxycamptothecin, paclitaxel, or fumagillin, and magnetic resonance imaging (MRI) techniques of tumors based on integrins targeting with Fe 3 O 4 NPs, computer tomography (CT) or MRI imaging with gadolinium chelate Au NPs, etc. 7,8 Human CA IX (hCA IX) is an extracellular, transmembrane isoform which was recently shown to constitute a novel and interesting target for the anticancer therapy due to its overexpression in many cancer tissues and not in their normal counterparts. 1b,9 Its expression is strongly induced by hypoxia present in many tumor tissues and correlated with a bad response to classical chemo-and radiotherapies. 1b,9 CA IX was shown to acidify the extratumoral medium leading both to the acquisition of metastasic phenotypes and to chemoresistance with many anticancer drugs, these processes being reverted by inhibition of the enzyme catalytic activity with sulfonamide inhibitors. 1b,9 The development of selective CA IX inhibitors might provide useful tools for highlighting the exact role of CA IX in hypoxic cancers, to control the pH imbalance of tumor cells and lead to novel diagnostic or therapeutic applications for the management of such tumors. 1b,9 Although many sulfonamide/sulfamate/sulfamide potent CA IX inhibitors were reported, few of them show an acceptable level of selectivity for inhibiting the transmembrane-tumor associated target isoform IX over the cytosolic, ubiquitous isozymes hCA I and II. 1b,9 Considering the extracellular localization of the target CA isoform and the fact that nanomaterials generally show membrane impermeability, 10 we report here the synthesis of CAI coated Au NPs which show excellent CA IX inhibitory properties and selectivity for the inhibition of the tumor-associated isoform over hCA I and II.The key intermediate 3a was synthesized by coupling lipoic acid 1 with 4-aminoethylbenzene sulfonamide 2a in the presence of EDCI/ DMAP, as outlined in Scheme 1. The CAI coated...