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Aminated silica hybrid, spin-crossover (SCO) nanoparticles (AmNPs) coupled with (S)-naproxen (NAP) are good candidates for drug nanocarriers.

The investigation and elaboration of the Spin-Crossover (SCO) phenomenon in Two – Dimensional (2D) Hofmann-type nanosized SCO materials and the size-reduction effect on cooperativity and thermodynamic properties of the nanoparticle are still in progress. Liquid Phase Exfoliation (LPE) as a top-down experimental protocol for the fabrication of 2D SCO atomically thin nanosheets is also an underexplored area of research. Given the increasing scientific interest for 2D nanosheets and their unique thickness-dependent electronic properties the above-mentioned study is of outmost importance. In this context, we present a detailed nano-synthetic study based on the reverse-micellar synthesis of [FeII(2-mpz)2Ni(CN)4] and a further rationalization of this method followed by LPE experimental protocols in order to synthesize nanoparticles with well-controlled size and shape. The role of concentration and reaction’s temperature is investigated in relation to the size, dispersion, morphology and magnetic properties of the nanoparticles. It was found that for specific values of these parameters the synthesis of nanoparticles is controlled and the final products are nanoparticles with an agglomerated architecture. According to an extensive Atomic Force Microscopy (AFM) Nano-topographic study, this agglomeration is best described as right truncated thick prisms of [FeII(2-mpz)2Ni(CN)4] stacked in a vertical position on a rectangular base plate. During the LPE procedure and by prolonging the sonication period the thick prisms are detached and, eventually, exfoliated to atomically thin right prism of height ~1 nm. Magnetic measurements revealed that the size reduction leads to the progressive downshift of abrupt thermal hysteresis with two-step SCO transition temperatures of the bulk [FeII(2-mpz)2Ni(CN)4] material to a gradual incomplete SCO behavior of an almost single layer 2D [FeII(2-mpz)2Ni(CN)4] nanosheet.

A reverse micelle method was used for the synthesis of water-soluble silica hybrid, spin-crossover (SCO) nanoparticles (NPs). MRI experiments provided temperature dependent T2 values, indicating their potential use as smart MRI agents, while lyophilization of NP dispersions in water yielded powders with a preserved but modified thermal hysteretic magnetic profile.

Spin Crossover (SCO) particles at the nanometric scale provide an alternative point of view and a new perspective concerning the development of a new generation of spintronic, electronic, photonic and mechanical devices. The coexistence of the SCO phenomenon with the accompanying hysteresis loop enhances the functionality of future devices for storing and processing information. Despite all promising facts, the SCO phenomena are greatly affected by cooperativity issues resulting in a direct relation between the decrease of the size of nanopatricle and the overall decrease of cooperativity towards more gradual spin transitions. This minireview aims to summarise the synthetic techniques for the synthesis of 2-D FeII SCO particles at the nanometric scale, an underexplored area of research, highlighting the effects of the size-reduction on the magnetic properties of the corresponding nanoparticles and hopefuly showcasing the importance of studying in the context of 2D limit the SCO phenomena.

This review is focused on the downsizing effect of a family of Hofmann-type Metal Organic Frameworks (MOFs) exhibiting Spin-Crossover Phenomenon (SCO) at high temperatures. Their nanoscale importan...

The diamagnetic two-dimensional Hofmann-type metal-organic framework [Zn

Herein we report the synthesis, isolation and structural characterization of hybrid microporous Hofmann-like spin crossover polymers with the molecular formula {Fe(C4H4N2)[M(CN)4]}·(C4H4N2)·1.2H2O where M = Pt(II) (1), Pd(II) (2). Magnetic susceptibility studies showed well-resolved hysteretic three-step for 1 and two-step for 2 thermally induced spin transitions.

The first use of the cyanoacetate ligand in 3d/4f-metal chemistry leads to {Fe2IIIM4III} (M = Dy, Gd, Y) coordination clusters with a squashed octahedral core structure; the DyIII compound exhibits slow relaxation of the magnetisation.

The study of the general reaction system Co(NO3)2·6H2O/Ln(NO3)3·6H2O (Ln = Tb, Dy, Ho, Er)/2-pyridinealdoxime (paoH)/Bun4NOH in MeCN under aerobic conditions provided access to fac-[CoIII(pao)3] (4). Starting from Co(II) sources, i.e. in the absence of LnIII ions, the known [Polyhedron 28 (2009) 1638] mer diastereoisomer, mer-[CoIII(pao)3] (3), could only be isolated. The crystallization of 4 is probably due to the formation of a mixed CoIII/LnIII species in solution, which already possesses the fac-{CoIII(pao)3} unit. The fac isomer 4 is converted readily to the mer-isomer 3, while the opposite transformation was not achieved under the reaction conditions employed. Complex [CoIII(pao)2(paoH)](ClO4) (5) was prepared in good yield from the aerobic reaction of Co(ClO4)2·6H2O and excess of paoH in MeOH. Treatment of 5 in MeCN/MeOH with one equivalent of base gives 3. The structures of the new complexes 4·MeCN and 5 have been determined by single-crystal X-ray crystallography. The distorted octahedral CoIII ion in 4 is coordinated by three N,N′-bidentate chelating ligands; the molecule is the facial diastereoisomer. The distorted octahedral CoIII center in the cation of 5 is coordinated by four nitrogen atoms of two pao− ligands and two nitrogen atoms of one neutral paoH molecule; the disposition of the donor atoms around the metal center is meridional. The cations [CoIII(pao)2(paoH)]+ form centrosymmetric dimers in the crystal lattice as a consequence of O(oxime)–H⋯O− (oximate) H bonds; the dimers form tetramers through weak C(oxime)–H⋯O(oxime) H-bonding interactions. Metric parameters show that the deprotonated oximato group of the pao− ligands in 4·MeCN and 5 is better described as . Solid-state UV–Vis and IR data are discussed in terms of the low-spin octahedral stereochemistry of CoIII and the nature of bonding, respectively. The 1NMR spectrum of 4·MeCN in CDCl3 provides strong evidence of the fac → mer transformation in solution.

International audience; The use of 2-pyridinealdoxime (paoH), methyl 2-pyridyl ketone oxime (mepaoH), phenyl 2-pyridyl ketone oxime (phpaoH) and pyridine-2-amidoxime (NH2paoH) for the synthesis of dinuclear CoIII/DyIII complexes is described in the absence or presence of an external base. Complexes [CoDy(pao)3(NO3)3] (1), [CoDy(mepao)3(NO3)3] (2), [CoDy(phpao)3(NO3)3] (3) and [CoDy(NH2pao)3(NO3)3]·3MeOH (4·3MeOH) have been isolated and their structures have been determined by single-crystal X-ray crystallography. The complexes crystallize in non-centrosymmetric (2, 3) or centrosymmetric (1, 4·3MeOH) trigonal space groups and form a family of triply-oximate bridged dinuclear Co(III)–Dy(III) complexes. The crystals of 1, 3 and 4·3MeOH contain mixtures of Δ and Λ enantiomers, whereas complex 2 is enantiomerically pure (Λ). A 3-fold crystallographic axis (C3) passes through two metal ions in all complexes. The low-spin CoIII and DyIII ions are bridged by three oximate groups belonging to the η1:η1:η1:μ 2-pyridyloximate ligands. The CoIII centre is octahedrally coordinated by the six nitrogen atoms of the deprotonated organic ligands in a facial arrangement. The DyIII centre is bound to an O9 set of donor atoms, its coordination sphere being completed by three bidentate chelating nitrato groups. The coordination polyhedron around DyIII in 1 is best described as the Johnson tricapped trigonal prism, while the coordination geometries of the DyIII centres in 2, 3 and 4·3MeOH are best described as consisting of spherical tricapped trigonal prismatic coordination polyhedra. The spectroscopic data of the complexes are also reported and discussed in the infra-red region in terms of the coordination modes of the ligands involved. The magnetic properties of these complexes were studied between 300 and 1.8 K revealing mainly the depopulation of the DyIIImj sublevels of the ground 6H15/2 state. The intrinsic magnetic anisotropy of the DyIII centers is clearly observed by the non-superimposed magnetization (M) versus H/T data, but single-molecule magnet (SMM) properties were detected only for the mepao−-containing complex 2. The origin of these properties in 2 is critically discussed and supported by computational studies.

The importance of 3d/4f-metal cluster chemistry is outlined, and the employment of 2-pyridyl ketone- and 2-pyridyl oxime-based ligands for the preparation of low-nuclearity NiII/LnIII complexes (Ln = lanthanide) is reviewed. The synthetic utility of the “metal complexes as ligands” and “one-pot” approaches is critically discussed. The small nuclearity of the products permits the in-depth analysis of their magnetic properties.

The first use of methyl 2-pyridyl ketone oxime (mpkoH) in zinc(II)/lanthanide(III) chemistry leads to the [ZnLn(mpko)3(mpkoH)3](ClO4)2 and [ZnLn(NO3)2(mpko)3(mpkoH)] families of dinuclear Zn(II)Ln(III) complexes displaying blue-green, ligand-based photoluminescence; the Zn(II)Dy(III) compound shows field-induced relaxation of magnetization.

The importance of 3d/4f-metal cluster chemistry is outlined, and the employment of 2-pyridyl ketone- and 2-pyridyl oxime-based ligands for the preparation of low-nuclearity Ni II /Ln III complexes (Ln = lanthanide) is reviewed. The synthetic utility of the "metal com- plexes as ligands" and "one-pot" approaches is critically discussed. The small nuclearity of the products permits the in-depth analysis of their magnetic properties.

The use of methyl 2-pyridyl ketone oxime (mpkoH) for the synthesis of Ni(II)/Ln(III) (Ln = lanthanide) complexes, using "one-pot" reactions in the absence of an external base, is described. Depending on the reaction and crystallization conditions employed, two families of complexes have been obtained. The first family consists of true heterometallic species and involves complexes [NiLn(mpko)(3)(mpkoH)(3)](ClO(4))(2), where Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er. The second family contains the pseudo heterometallic complexes [Ni(mpkoH)(3)](2)[Ln(NO(3))(6)](ClO(4)), where Ln = La, Ce, Pr, Nd and Sm. The crystal structures of [NiCe(mpko)(3)(mpkoH)(3)](ClO(4))(2) (1), [NiDy(mpko)(3)(mpkoH)(3)](ClO(4))(2) (8) and [Ni(mpkoH)(3)](2)[La(NO(3))(6)](ClO(4)) (11) have been determined by single-crystal, X-ray crystallography. Complexes 1·1.2MeOH·0.6H(2)O and 8·1.2MeOH·0.6H(2)O crystallise in the monoclinic space group P2(1)/a and are isomorphous; there are two crystallographically independent cations in the unit cell, but their interatomic distances and angles differ little. The Ni(II) and Ln(III) ions are bridged by three oximate groups belonging to the η(1):η(1):η(1):μ mpko(-) ligands. The Ni(II) centre is octahedrally coordinated by the six nitrogen atoms of the mpko(-) ligands in a facial arrangement. The Ln(III) centre is bound to an (O(oximate))(3)N(6) set of donor atoms, the nitrogen atoms belonging to the three N,N'-bidentate chelating mpkoH ligands. The stereochemistry of the Ln(III) atoms has been evaluated by means of continuous shape measures (CShM). The two crystallographically independent Ce(III) atoms in 1 have tricapped trigonal prismatic and capped square antiprismatic coordination geometries, while the polyhedra of the Dy(III) atoms in 8 are both close to a tricapped trigonal prism. The octahedral Ni(II) atoms in 11 are both facially bound to a N(6) set of donor atoms from three N,N'-bidentate chelating mpkoH ligands, while the 12-coordinate La(III) centre in [La(NO(3))(6)](3-) is coordinated by six bidentate chelating nitrato groups. Variable-temperature, solid state dc magnetic susceptibility studies were carried out on complexes 2, 6, 7 and 8. The dc susceptibility data for 6 in the 2.0-300 K range have been fit to a model with one J value, revealing an antiferromagnetic Ni(II)···Gd(III) exchange interaction [J = -1.1 cm(-1) based on H = -J (Ŝ(Ni)·Ŝ(Gd))]. Antiferromagnetic Ni(II)···Pr(III), Ni(II)···Tb(III) and Ni(II)···Dy(III) exchange interactions have also been suggested for 2, 7 and 8, respectively. The combined work demonstrates the usefulness of mpko(-) in the preparation of interesting Ni(II)/Ln(III) compounds, without requiring the presence of external base and ancillary organic ligands.