We report the synthesis, crystal structures, and magnetic properties of three Co(II) and two Ln(III) (Dy, Tb) complexes, all containing the tridentate ligand 2,6-bis(3-methoxypropyl-1H-benzimidazol-2-yl)pyridine (L). The pentacoordinate Co(II) complexes [Co(L)Cl2] (1) and [Co(L)Br2] (2) adopt distorted square-pyramidal geometries, while the heptacoordinate complexes [Co(L)(κ2-NO3)2] (3) contain two independent complex molecules with capped trigonal prismatic and pentagonal-bipyramidal shape of polyhedra. Lanthanide complexes [Dy(L)Cl3(H2O)] (4) and [Tb(L)Cl3(H2O)] (5) also adopt pentagonal-bipyramidal coordination environments and display characteristic 4f-4f emission bands in the solid state at 3 K. Ab initio calculations reproduce the observed anisotropy trends and rationalize the magnetic behaviour. Pentacoordinate Co(II) centres require an explicit Griffith-Figgis Hamiltonian approach, while heptacoordinate Co(II) complex 3 exhibits axial anisotropy rationalised by spin Hamiltonian formalism. Analysis of static magnetic properties of complexes 4 and 5 also revealed the notable magnetic anisotropy of the Ln(III) ions. AC susceptibility measurements reveal field-supported slow relaxation of magnetisation (SRM) in 1-4, with complexes 1-3 exhibiting single-channel relaxation and 4 displaying two relaxation pathways. In contrast, compound 5 shows no evidence of SRM. Analysis of the temperature dependence of the relaxation times yielded effective energy barrier (Ueff) values of 15.9(7) K for 1, 25.0(5) K for 2, 27(1) K for 3, and 33(3) K for 4. Comparative analysis across 3d and 4f systems highlights the crucial role of subtle ligand-field distortions and donor charge distribution in governing SIM performance. These findings expand the chemistry of pyridyl-benzimidazole-derived ligands and provide new design principles for both transition-metal and lanthanide single-ion magnets.

Correction for 'Unveiling field-induced single-ion magnetism in pentacoordinate and heptacoordinate cobalt(II), dysprosium(III) and terbium(III) complexes with a tridentate bis(benzimidazole)pyridine ligand' by Nikoleta Malinová et al., Dalton Trans., 2026, 55, 3975-3989, https://doi.org/10.1039/D5DT02849C.

Abstract Three isostructural dinuclear lanthanide complexes, [Ln2(μ-HL)2(HL)2(NO3)2]·4MeCN (Ln = DyIII (1), ErIII (2), YbIII (3)), were synthesized under base-free conditions using the o-vanillin- and 2-aminophenol-based Schiff base H2L. This ligand exhibits two distinct protonation-dependent coordination modes that have not been previously shown in this class of ligands. The simultaneous presence of monoanionic HL and monoanionic zwitterionic HL coordination leads to an unusual combination of chelating and asymmetric bridging features, generating a flexible and moderately axial LnO7N environment. All three complexes display field-induced single-molecule magnet behavior, and complex 1 additionally shows measurable zero-field slow relaxation. Detailed ac susceptibility studies indicate that their relaxation dynamics are dominated by Raman processes, with additional Orbach relaxation in 2 and a direct process in 3. We further combine dc and ac magnetic data with ab initio calculations, providing insight into the relaxation dynamics and the contributions of single-ion anisotropy and weak exchange interactions, if any. The combined structural, magnetic, and theoretical analyses demonstrate that base-free synthesis allows controlled ligand protonation, which in turn modulates crystal field effects and governs the magnetic relaxation pathways in these dinuclear lanthanide systems.

Designing graphene-based metal-free electrocatalysts is crucial due to their reduced costs, tunable molecular structures, superior electronic conductivity and substantial tolerance under fluctuating pH conditions. In this report, we have covalently functionalized fluoride graphite with n-octyl amine (OA), n-dodecyl amine (DDA), and n-octadecyl amine (ODA) via a facile nucleophilic substitution reaction to prepare three different N-alkylated fluorographene materials, OA-FGr, DDA-FGr, and ODA-FGr, respectively. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, and scanning electron microscopy (SEM) have collectively confirmed their successful formation by providing information about their functionality, stacking, chemical interactions, morphology and textural properties. Moreover, electron paramagnetic resonance (EPR) spectroscopy has been used to verify not only the functionalization but also the electrocatalytic properties. The synthesized materials have been utilized to prepare working electrodes to record linear sweep voltammetry (LSV) curves under acidic conditions (0.5 M H2SO4) and in an inert atmosphere at a scan rate of 5 mV s-1. ODA-FGr has demonstrated superior performance to its counterparts (OA-FGr and DDA-FGr), with an overpotential (η) of 530 mV at 10 mA cm-2 and a Tafel slope of 80 mV dec-1. Moreover, ODA-FGr has shown excellent durability, stability under accelerated test conditions (a scan rate of 100 mV s-1 and 2000 cycles) and reproducibility. Notably, the positive role of the alkyl chain length of amine molecules and their covalent functionalization is observed in improving HER performance and is found to be related to their amphiphilic nature and fluorine-to-nitrogen (F/N) ratio.

Hexanuclear cyclic Gd(III) coordination compounds are promising candidates for magnetic and magnetocaloric applications, yet systematic series remain rare due to synthetic challenges. We report the synthesis and characterization of five new complexes with the general formula [Gd(H3bt)(carboxylate)]6, employing four different carboxylate coligands. Single‑crystal X‑ray diffraction confirmed their isostructural nature, with polymorphism observed in the 4‑bromobenzoate derivatives. Magnetic properties were investigated using SQUID magnetometry and complemented by Broken Symmetry DFT calculations. The study reveals weak antiferromagnetic exchange interactions and notable magnetocaloric performance, with entropy changes approaching 28 J K- 1 kg- 1 at 2.7 K (other compounds measured at 2 K) and 9 T. Magneto‑structural correlations based on structural parameters and substituent effects were established, providing guidelines for tuning exchange interactions in cyclic Gd(III) systems. Incorporation of a thioether substituent further suggests potential for surface deposition, opening pathways toward device‑oriented applications.

The reaction of HL (2,6-bis-[{(methylthio)phenylimino}methyl]-4-methylphenol) with [Co2(mu-OH2)(O2CCMe3)4(HO2CCMe3)4] (Co 2 -Piv) in MeCN provided a trinuclear triangular-type complex [Co3L(mu 3-OH)(mu 1,3-O2CCMe3)3(O2CCMe3)]MeCN (1), whereas in another reaction, using Co(ClO4)26H2O as the source of CoII ions with the additional employment of NaOAc in MeOH resulted in a tetranuclear cubane-type complex [Co4L2(mu 3-OH)(mu 3-OMe)(mu 1,3-CH3CO2)2](ClO4)22.5H2O (2). The varying coordination behavior of the ligand was facilitated using two different CoII salts and the availability of different bridging anions, and the solvent medium used prompted two types of aggregations. Complex 1 has two CoII ions bound in the two adjacent pockets of L- in nearly octahedral geometry and one pivalate anion entangled tetrahedral CoII center. Complex 2 has four CoII centers, all having nearly octahedral geometry. From the alternating current (AC) susceptibility measurements, slow relaxation of magnetization for 1 becomes apparent on application of a DC field, but 2 does not exhibit slow magnetic relaxation, regardless of the applied DC field strength. The CASSCF/NEVPT2 calculations disclosed that the octahedral CoII sites in both 1 and 2 have easy-plane magnetic anisotropy of D in the +56.46-63.8 cm-1 range and the transverse component |E| in the 4.96-12.95 cm-1 range. The unique tetrahedral CoII center in 1 holds D = -6.46 cm-1 and |E| = 0.027 cm-1 with a negligible predisposition for quantum tunneling of magnetization, reinforcing the occurrence of field-induced slow magnetic relaxation of 1.

We report the synthesis and characterization of a new Schiff base ligand (HL), derived from 2-picolylamine and 2-hydroxy-3-methoxy-5-methylbenzaldehyde. Its reaction with Ni(NO3)2·6H2O and Ln(NO3)3·xH2O (Ln = GdIII, TbIII, DyIII) in the presence of triethylamine affords a carbonato-bridged family of heterobimetallic Ni4Ln2 complexes: [Ni4Ln2(L)2(L')2(μ-CO3)2(NO3)2]·xMeOH·yH2O (1-3). During the complexation reaction, ligand HL undergoes an in situ oxidation, followed by C-C coupling to generate a secondary ligand (H3L'). A similar transformation of the ligand was also observed in the isolated square planar NiII complex [Ni(HL')]·1.5MeOH·0.5H2O. X-ray crystallography confirms that 1-3 are isomorphous, featuring a rare combination of both paramagnetic and diamagnetic NiII ions. The magnetic measurements reveal an intramolecular NiII-LnIII ferromagnetic interaction and slow relaxation of magnetization in all three complexes, further supported by DFT and ab initio studies. Beyond magnetism, these complexes act as efficient catalysts for the fixation of CO2 into cyclic carbonates. Epoxide conversion proceeds with low catalyst loading, affording high yields (82-98%) at 70-100 °C within 4-6 h. Gram-scale reactions validate practical utility, while green metrics highlight sustainability (E-factor 3.73, excellent Eco-scale). Substrate scope includes aliphatic, phenoxyalkyl, and disubstituted oxiranes. Mechanistic insights underscore the cooperative roles of NiII and LnIII centers, providing valuable guidelines for designing multifunctional catalysts for sustainable CO2 utilization.

The synthesis and characterization of four new iron(III) coordination compounds with saltrien-like hexadentate Schiff base ligands Ln, prepared by condensation between triethylenetetramine and 2-hydroxy-3,5-dimethylbenzophenone (L1, C1-C3) or 2-hydroxy-5-methoxybenzophenone (L2, C4), are reported. The complexes [Fe(Ln)]X·mCH3CN (X = SeCN- for C1 and C4, SCN- for C2 and BPh4- for C3, m = 0 for C3, m = 1 for C1 and C4, m = 2 for C2) were structurally characterized, and their spin-crossover (SCO) was monitored by magnetic measurements, X-ray powder diffraction analysis, and EPR spectroscopy. Intermolecular interactions relevant to SCO were analyzed through Hirshfeld surface maps and QT-AIM calculations. All compounds exhibit SCO above room temperature in their solvated forms, and ab initio calculations were employed to probe their electronic structures. While the computed 2T2g-6A1g gaps and 10Dq energies are consistent across the whole series, the experimental T1/2 values do not directly reflect these energy differences. Instead, SCO is predominantly controlled by crystal packing effects, including intermolecular connectivity, internal pressure, lattice rigidity, and solvation. Upon heating, solvent removal in C1 and C2 shifts their SCO to below room-temperature. The desolvated compounds C1d and C2d exhibit sharp SCO with wide hysteresis, while C2d additionally features a second gradual step (C1d: T1/2 = 82 K/166 K; C2d: T(1)1/2 = 170 K/153 K, T(2)1/2 = 110 K). Furthermore, both compounds are LIESST active upon blue light irradiation (T(LIESST)=57 K for C1d and 36 K for C2d). These results underscore the crucial role of ligand flexibility, solvation, and intermolecular interactions on SCO and highlight the potential of these iron(III) complexes in molecular switching applications.

Two bidentate ligands (L1 = 1-pentyl-2-(pyridin-2-yl)-1H-benzimidazole and L2 = 1-heptyl-2-(pyridin-2-yl)-1H-benzimidazole) were employed for the synthesis of five mononuclear Fe(ii) coordination compounds 1-5 containing perchlorate, tetrafluoroborate and triflate counterions. Single-crystal X-ray diffraction analysis confirmed the expected molecular structures of all the reported compounds, revealing a moderately distorted octahedral geometry of {FeN6} coordination chromophores. All five compounds exhibit thermal spin crossover with T1/2 temperatures allocated above 400 K. The theoretical calculations supported the experimental magnetic investigation and helped to explain the electronic structures of the reported complexes with respect to the occurrence of thermal spin state switching. In addition, compound 4 was employed for the preparation of Langmuir-Blodgett films and fabrication of molecular films using the method of spontaneous evaporation of the subphase. While the formation of Langmuir-Blodgett films was unsuccessful due to the instability of the compound at the water/air interface, the latter technique allowed the formation of molecular films of 4 with well-defined thickness and homogeneity.

Three nickel, copper, and zinc complexes with dicarboxylic acids (3,3′-dithiodipropionic acid (H2dtdp) and fumaric acid (H2fu)) and N-donor ligands (1,10-phenanthroline (phen), N′–methyldipropylenetriamine (mdpta), and N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdien)) were synthesized. These complexes were characterized using elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Interestingly, [Ni(dtdp)(phen)(H2O)3]∙0.5H2O (1) is a mononuclear complex, where the dtdp dianion employs only one carboxylate group for coordination to the central nickel atom. [(ClO4)(mdpta)Cu(μ-dtdp)Cu(mdpta)(H2O)](ClO4) (2) is a dinuclear copper complex with a dtdp bridge and different coordination on the copper center. [{Zn(pmdien)(H2O)}2(μ-fu)](ClO4)2 (3) is a symmetric dimer with a bridging fumarate ligand. These coordination compounds were tested for their antibacterial activities on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis bacteria strains. All the complexes show moderate activities on the mentioned strains.

A zero-field Co( ii ) single-molecule magnet is reported based on a 2-formylphenoxyacetic acid derivative, and the study is complemented by theoretical calculations, resulting in the formulation of a correlation between the electronic structure and magnetic anisotropy.

A detailed computational study of hypothetical sandwich dysprosium double-decker complexes, bridged by various numbers of aliphatic linkers, was performed to evaluate the effect of the structural modifications on their ground-state magnetic sublevels and assess their potential as candidates for single-molecule magnets (SMMs). The molecular structures of seven complexes were optimized using the TPSSh functional, and the electronic structure and magnetic properties were investigated using the complete active space self-consistent field method (CASSCF). Estimates of the magnetic moment blocking barrier (Ueff) and blocking temperatures (TB) are reported. In addition, a new method based on computed derivatives of effective demagnetization barriers Ueff with respect to vibrational normal modes was introduced and applied to evaluate the impact of spin-phonon coupling on the SMM properties. On the basis of the computed parameters, we have identified promising candidates with properties superior to those of the existing single-molecule magnets.

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.

The Schiff base ligand, 2-(((2-hydroxybenzyl)imino)methyl)phenol (H2L) having ONO donor centres are utilized to synthesize {Ni4Dy3} coordination aggregate following the support of six benzoate bridging groups. Sequential addition of Dy(NO3)3.6H(2)O and NiCl2.6H2O to H2L followed by PhCO2Na completes the coordination driven aggregation of heptanuclear Na[Ni4Dy3(L)4(mu(3)-OH)(4)(mu 1,1,3,3-PhCO2)(2)(mu 1,3-PhCO2)(4)(CH3OH)(4)]center dot CH2Cl2.9H(2)O (1) having 2,3,6M7 - 1 topology. Two adjacent perpendicular inverse Ni2Dy2 partial di-cubane units sharing a common vertex through the central DyIII ion resulted a new structural arrangement within the Ni - Dy family of coordination aggregates. The complex shows no slow magnetic relaxation under zero applied fields and only shows a very weak field dependent magnetization. The DFT calculations revealed weak ferromagnetic exchange between benzoato-bridged NiII ions, whereas the CASSCF calculations were used to identify magnetic anisotropy in NiII and DyIII ions resulting in low-lying excited states of DyIII ions with significant probability for the quantum tunneling of the magnetization, which rationalize the observed fast dynamics in the magnetic properties.

A series of heterobimetallic LnIII-VIV compounds [Ln(VO)L(NO3)3(H2O)] (Ln = Gd(1), Tb(2), Dy(3), and Er(4)) assembled by a Schiff base ligand (H2L = N,N'-bis(1-hydroxy-2-benzylidene-6-methoxy)-1,7-diamino-4-azaheptane) were prepared and studied with experimental and theoretical methods. The single-crystal X-ray analysis revealed the change of the coordination number from 10 found in 1-3 to 9 confirmed in 4. The DC magnetic data were fit with several Hamiltonians to extract the exchange and anisotropy parameters of complexes 1-4. This investigation of magnetic properties was carried out using both DFT and CASSCF theoretical calculations. It was found out that exchange interactions in 1, 3 and 4 are antiferromagnetic, while 2 has ferromagnetic exchange interactions. Moreover, the AC susceptibility measurements revealed the field-induced slow relaxation of magnetization in complexes 2 and 3 which is complicated by the presence of three relaxation channels. Nevertheless, these compounds belong to the first TbIII-VIV and DyIII-VIV single-molecule magnets in this class of compounds.

Computational studies of sandwich dysprosium double-decker complexes [Dy(L)(2)](+/3+) as candidates for single-ion magnets with several inorganic aromatic ring systems (P-5(-), N-5(-), B3N3H6, B3P3H6, B3S3H3) have been performed. The molecular structures were optimized with the TPSSh functional, and the ground state properties were investigated with the complete active space SCF method (CASSCF) complemented by the dynamic correlation dressed correction (DCD-CAS(2)) or NEVPT2. Besides the evaluation of the magnetic moment blocking barrier, the impact of the molecular vibration on the relaxation of magnetization was also inspected. We were able to make predictions about the performance of those molecules as single-molecule magnets, where estimated effective energy barrier, U-eff, values are as high as 1475 K in the case of [Dy(N-5)(2)](-), which is the most anisotropic complex from our choice of studied compounds, making them a potentially very effective carbon-free alternative to organometallic double-decker dysprosocenium high-temperature single-molecule magnets.

A general correlation for Gd(iii) complexes showing the magnetocaloric effect was proposed.