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Achieving magnetic remanence at single isolated metal sites dispersed at the surface of a solid matrix has been envisioned as a key step toward information storage and processing in the smallest unit of matter. Here, we show that isolated Dy(III) sites distributed at the surface of silica nanoparticles, prepared with a simple and scalable two-step process, show magnetic remanence and display a hysteresis loop open at liquid 4He temperature, in contrast to the molecular precursor which does not display any magnetic memory. This singular behavior is achieved through the controlled grafting of a tailored Dy(III) siloxide complex on partially dehydroxylated silica nanoparticles followed by thermal annealing. This approach allows control of the density and the structure of isolated, "bare" Dy(III) sites bound to the silica surface. During the process, all organic fragments are removed, leaving the surface as the sole ligand, promoting magnetic remanence.

Two complexes {[GdCu5(GlyHA)5(H2O)7Cr(C2O4)3]·11.02H2O}n (1) and {{[GdCu5(GlyHA)5(H2O)6]μ2-[Cu(C2O4)2(H2O)]}2μ4-[Cu(C2O4)2]·15.8H2O}n (2), were obtained as outcomes of the reactions between the cationic hexanuclear {GdCu5(GlyHA)5}3+ 15-metallacrown-5 complex (where GlyHA2− = glycinehydroxamate) and the anionic oxalate complexes K3[Cr(C2O4)3] or K2[Cu(C2O4)2]. Both 1 and 2 possess polymeric 1D-chain structures according to X-ray structural analysis. As a consequence of the geometric orientations of the donor atoms in the oxalates from [Cr(C2O4)3]3−, the Cu5 mean planes of neighboring 15-metallacrown-5 units {GdCu5(GlyHA)5}3+ are angled at 75.5° to each other, which leads to formation of a zig-zag motif in the 1D-chains of complex 1. The centrosymmetric complex 2 contains two structurally different bis(oxalato)cuprate anions μ2-[Cu(C2O4)2(H2O)]2−, for one of which, coordination to two adjacent {GdCu5(GlyHA)5}3+ units leads to formation of linear 1D-chains in 2, while the second type, μ4-[Cu(C2O4)2]2−, is coordinated to four {GdCu5(GlyHA)5}3+ units, causing the cross-linking of single 1D-chains into a double-chain 1D coordination polymer. Studies of χMT vs. T data for 1 and 2 in a 2–300 K temperature range revealed the presence of both ferromagnetic and antiferromagnetic interactions amongst paramagnetic centres. The experimental χMT vs. T data for 1 were fitted using a model which takes into account exchange interactions between adjacent copper(II) ions, the Gd–Cu exchange interactions within {GdCu5(GlyHA)5}3+ units and additionally Gd–Cr exchange interactions. Fitting of the χMT vs. T data for 2 was not possible, since coordination of μ4-[Cu(C2O4)2]2− to {GdCu5(GlyHA)5}3+ led to the non-equivalence of several Cu–Cu exchange interactions within the metallacrown units and hence a superfluity of fittable parameters. Complexes 1 and 2 are the first examples of 15-metallacrown-5 complexes demonstrating a magnetocaloric effect (−ΔSM at 13 T reaches 24.26 J K−1 kg−1 at 5 K and 19.14 J K−1 kg−1 at 4 K for 1 and 2, respectively). [ABSTRACT FROM AUTHOR]

Since their discovery, [2.2]paracyclophane (pCp) and its derivatives have fascinated the scientific community due to their original molecular architecture and unusual electronic behavior. Over the years, significant efforts have been devoted to the development of substituted pCps for a variety of applications in different fields, ranging from organic synthesis and asymmetric catalysis to polymer chemistry and material science. This review describes a series of useful approaches that allow chemists to selectively decorate pCps, control the planar chirality that these molecules can display as soon as they are functionalized, and tune their photophysical behaviors. For each of these aspects of paracyclophane chemistry, selected examples of major advances are presented, and possible directions for future research are outlined. The application of pCp as central core for the development of uncommon 3D luminophores is finally highlighted. Emphasis is placed on the potential use of planar chiral luminescent paracyclophanes as antennas or ligands for the design of multifunctional lanthanide complexes, a quite underdeveloped but highly promising area for future research endeavors. [ABSTRACT FROM AUTHOR]

An in situ hydrolysis of the P–Cl bonds of the carbophosphazene [{NC(NMe2)}2{NPCl2}] (LPCl2) in the presence of hydrated lanthanide(III) nitrates in a dichloromethane and methanol (2 : 1) solvent mixture afforded a series of novel 1D coordination polymers: [{Ln(LHPO2)3(NO3)2(CH3OH)(H2O)} (Cl)]n {where Ln(III) = Gd (1), Tb (2), Dy (3), or Er (4) and LHPO2 is the hydrolyzed carbophosphazene (LPCl2) ligand}. X-ray crystallographic analysis revealed that complexes 1–4 are isostructural and crystallized in the monoclinic crystal system having P21/c space group. The coordination polymers are formed because of the involvement of the geminal P(O)(OH) moieties of the carbophosphazene ligand. Each lanthanide(III) ion is 9-coordinate (9O) in a distorted muffin geometry. Magnetic measurements revealed that both DyIII and ErIII analogues exhibit field-induced single-molecule magnet (SMM) behavior at 0.8 kOe and 2.2 k Oe, respectively. At such dc fields, the dynamic magnetic susceptibility displays complex behavior with a triple magnetic relaxation contribution for 3, while two contributions were identified for 4. The observed static and dynamic magnetic behavior for complexes 1–4 were further rationalized with the aid of BS-DFT and CASSCF/SO-RASSI/SINGLE_ANISO calculations. [ABSTRACT FROM AUTHOR]

Lanthanide Single‐Molecule Magnets are fascinating objects that break magnetic performance records with observable magnetic bistability at the boiling temperature of liquid nitrogen, paving the way for potential applications in high‐density data storage. The switching of lanthanide SMM has been successfully achieved using several external stimuli such as redox reaction, pH titration, light irradiation or solvation/desolvation thanks to the high sensitivity of the magnetic anisotropy to any structural change in the lanthanide surrounding. Nevertheless, the use of applied high pressure as an external stimulus is largely underused, especially considering that it can be combined with high pressure X‐ray diffraction to establish a complementary structure‐property relationship. This Concept article summarizes the few relevant examples of investigations of lanthanide SMMs under applied high pressure, provides conclusions on the effect of such stimulus on molecular structures and magnetic anisotropy, and finally draws perspective on the future development of magnetic measurements under applied pressure. [ABSTRACT FROM AUTHOR]

The association of lanthanide ions and paracyclophane derivatives has been very scarcely reported in the literature. In this study, elaboration of five coordination lanthanide complexes involving the 1,4(1,4)-dibenzenacyclohexaphane-12,43-diylbis(diphenylphosphine oxide) ligand (L) was achieved with the determination of single-crystal X-ray diffraction structures of four mononuclear complexes of formula [Ln(hfac)3(L)] (hfac- = 1,1,1,5,5,5-hexafluoroacetylacetonate) (Ln = Dy(III) (1-Dy) and Yb(III) (2-Yb)) and [Ln(tta)3(L)] (tta− = 2-tenoyl-trifluoroacetylacetonate) (Ln = Dy(III) (3-Dy) and Yb(III) (4-Yb)) and one dinuclear complex [Na(Dy2(hfac)6(L)2)](BArF) (BArF− = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) (5-Dy). The compounds were characterized using elemental analysis, IR spectroscopy, DC and AC magnetic measurements and photophysical investigations. L is an efficient organic chromophore for the sensitization of both visible Dy(III) (1-Dy) and near-infrared Yb(III) (2-Yb and 4-Yb) luminescence. The combination of excitation and emission spectra allowed the determination of the crystal field spitting of both the 2F7/2 ground state and 2F5/2 excited state for 2-Yb and 4-Yb. Moreover, 3-Dy and the two Yb(III) derivatives displayed field-induced single-molecule magnet (SMM) behaviour with slow magnetic relaxation occurring through the Raman process only for 2-Yb and 4-Yb, whereas a combination of Orbach and Raman processes was identified for 3-Dy. [ABSTRACT FROM AUTHOR]

We report three CoII-based complexes with the general formula [CoII(L)(X)2] by changing the halide/pseudo-halide ions [X = NCSe (1SeCN); Cl (2Cl) and Br (3Br)]. The obtained τ5 and CShM values confirm a distorted square pyramidal geometry around the CoII ion in all these complexes. In these three complexes, the central CoII ion is situated above the basal plane of the square pyramidal geometry. The extent of distortion from the ideal SPY-5 geometry differs upon changing the coordinating halide/pseudo-halide ion in these complexes. This essentially results in the alteration of the anisotropic parameter D and hence impacts the magnetic properties in these complexes. This phenomenon has been corroborated with the aid of theoretical investigations. All these complexes display field-induced SIM behaviour with magnetic relaxation occurring through a combination of processes depending on the applied dc magnetic field values and dilution. [ABSTRACT FROM AUTHOR]

The reaction between the ((E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide) (H2opch) ligand and the metallo-precursor [Dy(hfac)3]·2H2O led to the formation of an homometallic coordination complex with the formula [Dy2(hfac)3(H2O)(Hopch)2][Dy(hfac)4] (1). In presence of both [Dy(hfac)3] 2H2O and the Fe(II) salt, the heterobimetallic tetranuclear [FeDy3(hfac)8(H2O)2(opch)2] (2) was isolated, while the addition of the co-ligand 1,2-Bis(2-hydroxy-3-methoxybenzylidene) hydrazine (H2bmh) led to the formation of two heterobimetallic tetranuclear complexes with the formula [Fe3Dy(hfac)6(opch)2(H2bmh)] C6H14 (3) C6H14 and [Fe2Dy2(hfac)7(opch)2(H2bmh)] 0.5C7H16 (4) 0.5C7H16. Single crystal X-ray diffraction and dc magnetic investigation demonstrated that 3 and 4 involved the iron center in the +II and +III oxidation states. Dynamic magnetic measurements highlighted the single-molecule magnet behavior of 1 and 2 in a zero applied dc field primarily due to the ferromagnetic interactions taking place in these compounds. [ABSTRACT FROM AUTHOR]

In this work, a new family of binuclear NiII–LnIII complexes with the formula [NiLn(L)2(NO3)3]·0.5H2O (Ln = Gd, 1; Tb, 2; Dy, 3; Ho, 4; Er, 5; Yb, 6; Y, 7) was synthesized using a thioether group-bearing Schiff base. Due to the strict hard/soft dichotomy between the 4f and 3d metal ions, selective coordination of NiII and 4f metal ions was achieved with the adjacent soft ONS and hard OO binding pockets of the ligand. All the complexes 1–7 exhibit a NiII centre in a distorted pseudo-octahedral geometry with the LnIII centres in distorted bicapped square-antiprism geometry. The huge distortion around the NiII centres is triggered for the accommodation of larger lanthanoids to the adjacent OO coordination site, and this forces the NiII centres to have a tridentate coordination from the ONS, as intermediate between meridional and facial binding. Field-induced single-molecule magnetic behaviour was observed for heterodinuclear complexes involving Kramers lanthanide ions (LnIII = Dy, Er and Yb), with magnetic relaxation occurring through an Orbach process only for 5. DFT calculations using various functionals (BP86, B3LYP, PBE0, TPSSh, PWPB95, R2SCAN) were applied to calculate the isotropic exchange, showing good agreement with the experiment (JGd–Ni = +1.78 cm−1). CASSCF calculations for NiII and LnIII ions were also performed to reveal detailed information about their electronic structure and magnetic anisotropy, supporting the experimental observations. This study accentuates the mutual distortion of coordination geometry induced by flexibility of the ligand backbone with the simultaneous binding of two different metal ions. [ABSTRACT FROM AUTHOR]

This paper investigates the reactivity and optical properties of transition metal-incorporated organoantimony(V) clusters prepared by a solvothermal route. The detailed structural characterization of novel heterometallic M2Sb4 oxo clusters is reported herein. Single crystal X-ray diffraction revealed the formation of hexanuclear organoantimony(V) based oxo clusters [(p-ClC6H4Sb)4V2(O)2(μ3-O)2(μ2-O)2(t-BuPO3)4(μ2-OCH3)4] (1), [M2(p-iPr-C6H4Sb)4(μ3-O)2(μ2-O)2(μ2-OCH3)4(t-BuPO3)4(py)2]·xCH3OH, where M = Mn, x = 2 (2), Co, x = 1 (3), Ni, x = 2 (4) and Cu, x = 2 (5). The magnetic behaviour of the clusters was probed by magnetic susceptibility measurements. Optical absorption studies showed that bandgap reduction can be achieved by incorporating an appropriate transition metal into the homometallic Sb6 oxo cluster. [ABSTRACT FROM AUTHOR]

The interest for chiral tris(β‐diketonato)lanthanide complexes in coordination chemistry is huge due to its Lewis acid character, optical activity, and the control of the final compound architecture. The reaction of equimolar quantities of [Dy((−)/(+)hfc)3(H2O)] (hfc− = 3‐(heptafluoropropylhydroxymethylene)‐(+/−)‐camphorate) and L led to the formation of a pair of enantiomers for dinuclear complexes [Dy((−)/(+)hfc)3(L)]2⋅C7H16([(−)/(+)1]⋅C7H16) (L = 4′‐(4′′′‐pyridyl‐N‐oxide)‐1,2′:6′1′′‐bis‐(pyrazolyl)pyridine]). Starting from the previous experimental protocol with the addition of bulky BArF anions, a partial dissociation of the chiral [Dy((−)/(+)hfc)3(H2O)] was observed leading to the isolation of a mono‐dimensional cationic chiral polymer {[Dy((−)/(+)hfc)2(L)][BarF]}n⋅nCH3NO2([(−)/(+)2]n⋅nCH3NO2). Natural circular dichroism (NCD) highlighted an exciton CD couplet for [(−)/(+)2]n but not for (−)/(+)1. The latter behaves as a single‐molecule magnet (SMM) with a blocking temperature up to 4 K, whereas [(−)/(+)2]n is a 1D assembly of field‐induced SMMs with a magnetic relaxation occurring through a Raman process only. [ABSTRACT FROM AUTHOR]

The combination of physical properties sensitive to molecular chirality in a single system allows the observation of fascinating phenomena such as magneto‐chiral dichroism (MChD) and circularly polarized luminescence (CPL) having potential applications for optical data readout and display technology. Homochiral monodimensional coordination polymers of YbIII were designed from a 2,15‐bis‐ethynyl‐hexahelicenic scaffold decorated with two terminal 4‐pyridyl units. Thanks to the coordination of the chiral organic chromophore to Yb(hfac)3 units (hfac−=1,1,1,5,5,5‐hexafluoroacetylaconate), efficient NIR‐CPL activity is observed. Moreover, the specific crystal field around the YbIII induces a strong magnetic anisotropy which leads to a single‐molecule magnet (SMM) behaviour and a remarkable room temperature MChD. The MChD‐structural correlation is supported by computational investigations. [ABSTRACT FROM AUTHOR]