Investigation of slow magnetic relaxation in a series of 1D polymeric cyclobutane-1,1-dicarboxylates based on LnVIV2 units (Ln = Tb, Dy, Ho, Er, Tm, Yb): rare examples of V-4f single-molecule magnets.

The reactions of VOSO·3HO with Na(cbdc) (cbdc - dianion of cyclobutane-1,1-dicarboxylic acid) and lanthanide(III) nitrates taken in a molar ratio of 1 : 2 : 1 were found to yield a series of isostructural heterometallic compounds [NaLn(VO)(cbdc)(HO)] (1Ln, Ln = Tb, Dy, Ho, Er, Tm, Yb). These compounds are constructed from trinuclear anionic units [Ln(VO)(cbdc)(HO)] ({LnV}) linked by Na ions into 1D polymeric chains. The crystal structures of 1Dy and 1Er were determined by single-crystal X-ray diffraction (XRD), and their isostructurality with 1Tb, 1Ho, 1Tm, and 1Yb was proved by powder X-ray diffraction (PXRD).

Lanthanide(III) SMMs with cationic and anionic complex fragments formed by a Schiff base: structure, luminescence, magnetic properties and calculations.

The syntheses, structures, luminescence and magnetic properties of a new series of Ln(III) complexes of the formula [Ln(L)(HO)(DMF)][Ln(L)] (in which HL is ,'-ethylaminebis[1-phenyl-3-methyl-4-formylimino-2-pyrazoline-5-one]; Ln(III) - Gd (1), Tb (2), or Dy (3) ions). The crystal structures were determined by single-crystal X-ray diffraction measurements for all the above-mentioned complexes. The crystals of these compounds consist of cationic [Ln(L)(HO)(DMF)] and anionic [Ln(L)] moieties which form a 3D supramolecular architecture by the H-bonds and electrostatic forces.

Inductive detection of temperature-induced magnetization dynamics of molecular spin systems.

The development and technological applications of molecular spin systems require versatile experimental techniques to characterize and control their static and dynamic magnetic properties. In the latter case, bulk spectroscopic and magnetometric techniques, such as AC magnetometry and pulsed electron paramagnetic resonance, are usually employed, showing high sensitivity, wide dynamic range, and flexibility. They are based on creating a nonequilibrium state either by changing the magnetic field or by applying resonant microwave radiation.

Field induced slow magnetic relaxation in a linear homotrinuclear manganese heterospin coordination compound with = 7/2 ground state and intriguing spin density distribution.

We report a first example of field-induced ( = 2500 Oe) slow magnetization relaxation in the homotrinuclear linear heterospin manganese coordination compound with = 7/2 ground state, based on the bidentate 3,5-di--butyl-1,2-benzoquinone-1-monooxime (HL) ligand with composition {[MnL]Mn[MnL]}.

Ferrocenyl-substituted nitronyl nitroxide in the design of one-dimensional magnets.

By the reaction of M(hfac) (M = Mn(II), Co(II), Cu(II), and Zn(II); hfac is the hexafluoroacetylacetonate anion) and ferrocenyl-substituted nitronyl nitroxide (L), we succeeded in the synthesis of stable heterospin complexes: mononuclear [Zn(hfac)L], trinuclear {[Cu(hfac)]L} and chain polymer [Mn(hfac)L] and [Co(hfac)L]. The specific steric bulkiness of the ferrocenyl substituent leads to the formation of -type coordination polyhedra in the [Mn(hfac)L] and [Co(hfac)L] chains. The introduction of the ferrocene substituent leads to an effective weakening of intermolecular or interchain magnetic exchange coupling.

Effects of solvatomorphism, the nature of a chelating ligand synthon and a counterion on the single crystal XRD structure and SMM properties of paramagnetic monocapped cobalt(II) tris-pyrazoloximates.

A series of monocapped cobalt(II) tris-pyrazoloximates was obtained through the template condensation of the corresponding pyrazoloxime, phenylboronic acid and a suitable cobalt(II) halogenide. Comparing 3-acetylpyrazoloxime its methine-containing homolog, the former produced cobalt(II) clathrochelates in substantially higher yields due to the electron donating effect of the methyl substituent, increasing the N-donor ability of its oxime group. Their less N-donor analog with the electron acceptor trifluoromethyl group did not form cobalt(II) complexes of this type.

Novel stable ytterbium acetylacetonate-quinaldinate complexes as single-molecule magnets and surprisingly efficient luminophores.

The first Yb complexes comprising a quinoline-2-carboxylate (quinaldinate, Q) ligand, namely 1D-polymeric [Yb(acac)(Q)] (1, acac is the acetylacetonate (pentane-2,4-dionate) anion) and mononuclear [Yb(acac)(Q)(Phen)] (2, Phen is 1,10-phenanthroline), are reported. The bifunctionality of both complexes as field-induced single-molecule magnets (SMMs) and near IR luminophores has been revealed. The SMM properties of 1 and 2 have been discussed in terms of the geometry and composition of the coordination environment.

Two Discoveries in One Crystal: σ-Type Oxime Radical as an Unforeseen Building Block in Molecular Magnetics and Its Spatial Structure.

In the present work, the study of the unusual interaction between copper hexafluoroacetylacetonate and the diacetyliminoxyl radical resulted in two discoveries from different fields: the determination of the oxime radical spatial structure and the introduction of an oxime radical into the field of molecular magnetic material design. Oxime radicals are key plausible intermediates in the processes of oxidative CH-functionalization and in the synthesis of functionalized isoxazolines from oximes. Due to the lack of X-ray diffraction data for oxime radicals, the knowledge about their structure is based mainly on indirect approaches, spectroscopic methods (electron paramagnetic resonance and IR), and quantum chemical calculations.

Synthesis, X-ray structure and magnetic properties of the apically functionalized monocapped cobalt(II) tris-pyridineoximates possessing SMM behaviour.

The title cobalt(II) pseudoclathrochelate complexes possess an intermediate trigonal prismatic-trigonal antiprismatic geometry. As follows from PPMS data, they exhibit an SMM behaviour with Orbach relaxation barriers of approximately 90 K. Paramagnetic NMR experiments confirmed a persistence of these magnetic characteristics in solution.

Aerogel-Based Single-Ion Magnets: A Case Study of a Cobalt(II) Complex Immobilized in Silica.

The chemical immobilization of cobalt(II) ions in a silica aerogel matrix enabled the synthesis of the first representative example of aerogel-based single-ion magnets. For the synthesis of the lyogels, methyl-trimethoxysilane and N-3-(trimethoxysilyl)propyl ethylenediamine were co-hydrolyzed, then the ethylenediamine groups that were immobilized on the silica matrix enabled the subsequent binding of cobalt(II) ions. Lyogels with various amounts of ethylenediamine moieties (0.

Change in the Electronic Structure of the Cobalt(II) Ion in a One-Dimensional Polymer with Flexible Linkers Induced by a Structural Phase Transition.

A new 1D-coordination polymer [Co(Piv)(NH(CH)NH)] (, Piv is MeCCO anion) was obtained, the mononuclear fragments {Co(OCR)} within which are linked by μ-bridged molecules of hexamethylenediamine (NH(CH)NH). For this compound, two different monoclinic 2/ (α-) and 2/ (β-) phases were found at room temperature by single-crystal X-ray diffraction analysis, with a similar structure of chains and their packages in unit cells. The low-temperature phase (γ-) of crystal at 150 K corresponds to the triclinic space group -1.

Ni Nanoparticles Stabilized by Hyperbranched Polymer: Does the Architecture of the Polymer Affect the Nanoparticle Characteristics and Their Performance in Catalysis?

Heat-up and hot-injection methods were employed to synthesize Ni nanoparticles (NPs) with narrow size distribution in the presence of hyperbranched pyridylphenylene polymer (PPP) as a stabilizing agent. It was shown that depending on the synthetic method, Ni NPs were formed either in a cross-linked polymer network or stabilized by a soluble hyperbranched polymer. Ni NPs were characterized by a combination of transmission electron microscopy (TEM), scanning TEM, thermogravimetric analysis, powder X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray analysis, and magnetic measurements.

Magnetically bistable cobalt-dioxolene complexes with a tetradentate N-donor base.

Synthesis and magnetic characterization of a family of cobalt-dioxolene complexes [(MeTPA)Co(36-DBCat)] (1), [(MeTPA)Co(36-DBCat)](PF) (2) and [(MeTPA)Co(diox-(OMe))](BPh) (3) (MeTPA = bis(6-methyl-2-pyridyl)methyl-(2-pyridylmethyl)amine; 36-DBCat = dianion of 3,6-di--butylcatechol; diox-(OMe) - 2,5-di--butyl-3,3,4-trimethoxy-6-oxocyclohexa-1,4-dienolate) is reported. The neutral complex 1 is found to form hexa- (CoON, 1a) and pentacoordinated (CoON, 1b) isomers. Variable temperature single crystal X-ray diffraction analysis of 1a and 1b clearly indicates the presence of the high-spin divalent metal ion and the dianionic catecholate form of the dioxolene ligand.

Field-Induced Slow Magnetic Relaxation in Co Cyclopropane-1,1-dicarboxylates.

New Co substituted malonate field-induced molecular magnets {[RbCo(cpdc)(HO)]∙6HO} () and [CsCo(cpdc)(HO)] () (where cpdc stands for cyclopropane-1,1-dicarboxylic acid dianions) were synthesized. Both compounds contain mononuclear bischelate fragments {Co(cpdc)(HO)} where the quasi-octahedral cobalt environment (CoO) is complemented by water molecules in apical positions. The alkali metal atoms play the role of connectors between the bischelate fragments to form 3D and 2D polymeric structures for and , respectively.

Series of Fluorinated Benzimidazole-Substituted Nitronyl Nitroxides: Synthesis, Structure, Acidity, Redox Properties, and Magnetostructural Correlations.

A special series of nitronyl nitroxides was synthesized: 2-(benzimidazol-2'-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1-imidazole-3-oxide-1-oxyls mono-, di-, tri-, or tetrafluorinated on the benzene ring. The structure of all paramagnets was unambiguously confirmed by single-crystal X-ray diffraction. It was found that in crystals, the radicals are assembled into chains due to intermolecular H-bonds between the benzimidazole moiety (H-bond donor) and the nitronyl nitroxide group or benzimidazole ring (H-bond acceptor).

Spin transitions in ferric catecholate complexes mediated by outer-sphere counteranions.

A family of ionic ferric catecholate complexes 1-4 bearing a disubstituted 3,6-di--butyl-catecholate ligand (3,6-DBCatH) and tetradentate tris(2-pyridylmethyl)amine (TPA) was prepared and its spin transitions were investigated. Variation of the outer-sphere counteranions (PF, BPh, ClO, BF) is accompanied by changes in the magnetic behavior of the compounds under consideration. The crystal structures of complexes 1, 3 and 4 were determined by single crystal X-ray diffraction analysis at 100 K and 293 K.

Mononuclear Transition Metal Cymantrenecarboxylates as Precursors for Spinel-Type Manganites.

Novel mononuclear cymantrenecarboxylate complexes of transition metals, [Co(HO)](CymCO)·4HO (Cym = (η-CH)Mn(CO)) (), [Ni(HO)](CymCO)·4HO (), [Zn(HO)](CymCO)·4HO (), [Co(CymCO)(imz)] (imz = imidazole, ), [Co(CymCO)(bpy)]·2PhMe (bpy = 2,2'-bipyridyl, ), [Ni(CymCO)(bpy)(HO)][CymCO]·0.5MePh·2HO (), [Cu(CymCO)(imz)] (), and [Cu(CymCO)(bpy)(HO)] (), were obtained and characterized by single-crystal X-ray analysis. Complexes - are isostructural.

3D-Printed Porous Magnetic Carbon Materials Derived from Metal-Organic Frameworks.

Here we report new porous carbon materials obtained by 3D printing from photopolymer compositions with zinc- and nickel-based metal-organic frameworks, ZIF-8 and Ni-BTC, followed by high-temperature pyrolysis. The pyrolyzed materials that retain the shapes of complex objects contain pores, which were produced by boiling zinc and magnetic nickel particles. The two thus provided functionalities-large specific surface area and ferromagnetism-that pave the way towards creating heterogenous catalysts that can be easily removed from reaction mixtures in industrial catalytic processes.

Tetranuclear Cr-Ln ferrocenecarboxylate complexes with a defect-dicubane structure: synthesis, magnetism, and thermolysis.

Using ferrocenecarboxylic acid (FcCOH) and triethanolamine (Htea) as ligands, the isostructural heterotrimetallic complexes [LnIII2CrIII2(OH)(FcCO)(NO)(Htea)]·2MePh·2THF (Ln = Tb (1), Dy (2), Ho (3), Er (4), and Y (5); Fc = (η-CH)(η-CH)Fe; Htea = N(CHCHOH)) were obtained. In all of the complexes which possess a defective dicubane structure, two doubly deprotonated triethanolamine ligands chelate the chromium ions. However, during the synthesis of 1, an isomeric complex 1a in which Tb is chelated by triethanolamine as a tetradentate ligand, was also isolated as a few single crystals.

Two types of LnCu hydroxo-trimethylacetate complexes with 0D and 1D motifs: synthetic features, structural differences, and slow magnetic relaxation.

Two series of heterometallic Ln-Cu compounds containing a butterfly-like tetranuclear metal core were synthesized and characterized by X-ray diffraction and magnetometry. The structures of the new compounds were shown to depend on the nature of the hydroxide used for the synthesis. The reactions of copper(II) and lanthanide(III) salts with Hpiv (Hpiv is trimethylacetic acid) and LiOH in a MeCN-EtOH mixture afford the molecular complexes [LnCu(μ-OH)(piv)(HO)]·4EtOH (1Ln, Ln = Gd, Tb, Dy, Ho, Yb), whereas the similar reactions using NaOH instead of LiOH give the 1D coordination polymers [NaLnCu(μ-OH)(piv)(EtOH)]·EtOH (2Ln, Ln = Gd, Tb, Dy, Ho, Yb).

Switchable Aromaticity of Phthalocyanine via Reversible Nucleophilic Aromatic Addition to an Electron-Deficient Phosphorus(V) Complex.

Reversible nucleophilic addition to a phthalocyanine core was observed for the first time for the electron-deficient cationic phosphorus(V) complex [PcP(OMe)], whose reaction with KOH afforded a highly distorted nonaromatic adduct bearing an OH group at one of the α-pyrrolic carbon atoms. This adduct was characterized by single-crystal X-ray diffraction, ESI HRMS, and NMR, and UV-vis spectroscopy, together with quantum-chemical modeling. The acidic treatment of this adduct restored aromaticity and recovered the starting cationic complex.

Cadmium-Inspired Self-Polymerization of {LnCd} Units: Structure, Magnetic and Photoluminescent Properties of Novel Trimethylacetate 1D-Polymers (Ln = Sm, Eu, Tb, Dy, Ho, Er, Yb).

A series of heterometallic carboxylate 1D polymers of the general formula [LnCd(piv)(HO)]·nMeCN (Ln = Sm (), Eu (), Tb (), Dy (), Ho (), Er (), Yb (); piv = anion of trimethylacetic acid) was synthesized and structurally characterized. The use of Cd instead of Zn under similar synthetic conditions resulted in the formation of 1D polymers, in contrast to molecular trinuclear complexes with LnZn cores. All complexes - are isostructural.

Generation of a Hetero Spin Complex from Iron(II) Iodide with Redox Active Acenaphthene-1,2-Diimine.

The reaction of the redox active 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) and iron(II) iodide in acetonitrile led to a new complex [(dpp-BIAN)FeI] (). Molecular structure of was determined by the single crystal X-ray diffraction analysis. The spin state of the iron cation in complex at room temperature and the magnetic behavior of in the temperature range of 2-300 K were studied using Mossbauer spectroscopy and magnetic susceptibility measurements, respectively.

Versatile Reactivity of Mn Complexes in Reactions with N-Donor Heterocycles: Metamorphosis of Labile Homometallic Pivalates vs. Assembling of Endurable Heterometallic Acetates.

Reaction of 2,2'-bipyridine (2,2'-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)(EtOH)] led to the formation of binuclear complexes [Mn(Piv)L] (L = 2,2'-bipy (), phen (); Piv is the anion of pivalic acid). Oxidation of or by air oxygen resulted in the formation of tetranuclear Mn complexes [MnO(Piv)L] (L = 2,2'-bipy (), phen ()). The hexanuclear complex [Mn(OH)(Piv)(pym)] () was formed in the reaction of [Mn(Piv)(EtOH)] with pyrimidine (pym), while oxidation of produced the coordination polymer [MnO(Piv)(pym)] ().

Molecular and Polymer LnM (Ln = Eu, Gd, Tb, Dy; M = Zn, Cd) Complexes with Pentafluorobenzoate Anions: The Role of Temperature and Stacking Effects in the Structure; Magnetic and Luminescent Properties.

Varying the temperature of the reaction of [{Cd(pfb)(HO)}·(pfb)], [Ln(pfb)(HO)]·HO (Hpfb = pentafluorobenzoic acid), and 1,10-phenanthroline (phen) in MeCN followed by crystallization resulted in the isolation of two type of products: 1D-polymers [LnCd(pfb)(phen)]1.5MeCN (Ln = Eu (I), Gd (II), Tb (III), Dy (IV)) which were isolated at 25 °C, and molecular compounds [TbCd(pfb)(phen)] (V) formed at 75 °C. The transition from a molecular to a polymer structure becomes possible because of intra- and intermolecular interactions between the aromatic cycles of phen and pfb from neighboring tetranuclear LnCd fragments.