Above room temperature spin crossover in mononuclear iron(II) complexes featuring pyridyl-benzimidazole bidentate ligands adorned with aliphatic chains.

Two bidentate ligands (L1 = 1-pentyl-2-(pyridin-2-yl)-1-benzimidazole and L2 = 1-heptyl-2-(pyridin-2-yl)-1-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 {FeN} coordination chromophores. All five compounds exhibit thermal spin crossover with temperatures allocated above 400 K.

Correction: Atropisomeric 1-phenylbenzimidazoles affecting microtubule organization: influence of axial chirality.

Correction for 'Atropisomeric 1-phenylbenzimidazoles affecting microtubule organization: influence of axial chirality' by Jana Pospíšilová , , 2024, https://doi.org/10.1039/d4ob00863d.

Magnetic anisotropy and slow relaxation of magnetisation in double salts containing four- and six-coordinate cobalt(II) complex ions.

Four novel Co(II) coordination compounds 1-4 of the general formula [Co(L)][Co(NCY)]·CHCN (where L are tridentate ligands L1 = 2,6-bis(1-hexyl-1-benzimidazol-2-yl)pyridine for 1 and 2; L2 = 2,6-bis(1-octyl-1-benzimidazol-2-yl)pyridine for 3; L3 = 2,6-bis(1-dodecyl-1-benzimidazol-2-yl)pyridine for 4, Y = O for 1, 3, and 4 and Y = S for 2; = 0 for 1 and 3, = 0.5 for 2 and = 2 for 4) were prepared and characterised. The molecular structures of all four compounds consist of the hexacoordinate complex cation [Co(L)] and tetracoordinate complex anion [Co(NCY)], with distorted octahedral and tetrahedral symmetry of coordination polyhedra, respectively.

Atropisomeric 1-phenylbenzimidazoles affecting microtubule organization: influence of axial chirality.

Benzimidazoles are frequently used in medicinal chemistry. Their anticancer effect is among the most prominent biological activities exhibited by this scaffold. Although numerous benzimidazole derivatives have been synthesized, possible atropisomerism of -substituted 1-phenylbenzimidazoles has been largely overlooked.

Photoswitchable hydrazones with pyridine-based rotors and halogen substituents.

The ,-photoisomerization of pyridine-based hydrazone switches is typically suppressed due to the presence of pyridine-based rotors. The crystal structures of studied compounds were investigated using theoretical methods combining DFT and QT-AIM calculations to unveil the nature and properties of the intramolecular hydrogen bonding. In this study, we introduced a new series of pyridine-based hydrazones anchored with -halogen substituents (2-X) and investigated their photoswitching abilities using H NMR and UV-Vis spectroscopy.

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.

Levamisole Based Co(II) Single-Ion Magnet.

A new Co(II) complex, [Co(NCS)(L)] (1) has been synthesized based on levamisole (L) as a new ligand. Single-crystal X-ray diffraction analyses confirm that the Co(II) ion is having a distorted tetrahedral coordination geometry in the complex. Notably strong intramolecular S⋅⋅⋅S and S⋅⋅⋅N interactions has been confirmed by employing Quantum Theory of Atoms in Molecules (QTAIM).

Partial Thermal Condensation Mediated Synthesis of High-Density Nickel Single Atom Sites on Carbon Nitride for Selective Photooxidation of Methane into Methanol.

Direct selective transformation of greenhouse methane (CH) to liquid oxygenates (methanol) can substitute energy-intensive two-step (reforming/Fischer-Tropsch) synthesis while creating environmental benefits. The development of inexpensive, selective, and robust catalysts that enable room temperature conversion will decide the future of this technology. Single-atom catalysts (SACs) with isolated active centers embedded in support have displayed significant promises in catalysis to drive challenging reactions.

Tetracoordinate Co(II) complexes with semi-coordination as stable single-ion magnets for deposition on graphene.

We present a theoretical and experimental study of two tetracoordinate Co(II)-based complexes with semi-coordination interactions, , non-covalent interactions involving the central atom. We argue that such interactions enhance the thermal and structural stability of the compounds, making them appropriate for deposition on substrates, as demonstrated by their successful deposition on graphene. DC magnetometry and high-frequency electron spin resonance (HF-ESR) experiments revealed an axial magnetic anisotropy and weak intermolecular antiferromagnetic coupling in both compounds, supported by theoretical predictions from complete active space self-consistent field calculations complemented by N-electron valence state second-order perturbation theory (CASSCF-NEVPT2), and broken-symmetry density functional theory (BS-DFT).

Rh(III) and Ru(II) complexes with phosphanyl-alkylamines: inhibition of DNA synthesis induced by anticancer Rh complex.

This investigation was designed to synthesize half-sandwich Rh(III) and Ru(II) complexes and study their antiproliferative activity in human cancer cell lines. Nine compounds were prepared and tested by various assays for their anticancer activity and mechanism of action. Hit Rh(III) complex showed low-micromolar potency in cisplatin-sensitive (A2780) and -resistant (A2780cis) ovarian carcinoma cell lines, promising selectivity toward these cancer cells over normal lung fibroblasts and an unprecedented mechanism of action in the treated cells.

Axially Chiral Sulfonic Acids for Brønsted Acid Catalysis: 8-Benzoimidazolylnaphthalene-1-sulfonic Acids and Their Derivatives.

A new type of axially chiral sulfonic acid was developed. The synthesis is based on cheap commercially available materials and a practical method for optical resolution via diastereomeric salt formation, which can provide both enantiomers. Eleven benzoimidazolylnaphthalenesulfonic acids were prepared and four of them were isolated as pure and stable atropisomers.

Trigonally Distorted Hexacoordinate Co(II) Single-Ion Magnets.

By simple reactions involving various cobalt(II) carboxylates (acetate and in situ prepared pivalate and 4-hydroxybenzoate salts) and neocuproine (neo), we were able to prepare three different carboxylate complexes with the general formula [Co(neo)(RCOO)] (R = -CH for , (CH)C- for , and 4OH-CH- for ). The [Co(neo)(RCOO)] molecules in the crystal structures of - adopt a rather distorted coordination environment, with the largest trigonal distortion observed for , whereas and are similarly distorted from ideal octahedral geometry. The combined theoretical and experimental investigations of magnetic properties revealed that the spin Hamiltonian formalism was not a valid approach and the L-S Hamiltonian had to be used to reveal very large magnetic anisotropies for -.

Ratiometric pH-Responsive F Magnetic Resonance Imaging Contrast Agents Based on Hydrazone Switches.

Hydrazone-based molecular switches serve as efficient ratiometric pH-sensitive agents that can be tracked with F NMR/MRI and H NMR. Structural changes induced between pH 3 and 4 lead to signal appearance and disappearance at H and F NMR spectra allowing ratiometric pH measurements. The most pronounced are resonances of the CF group shifted by 1.

3d-4f magnetic exchange interactions and anisotropy in a series of heterobimetallic vanadium(IV)-lanthanide(III) Schiff base complexes.

A series of heterobimetallic Ln-V compounds [Ln(VO)L(NO)(HO)] (Ln = Gd(1), Tb(2), Dy(3), and Er(4)) assembled by a Schiff base ligand (HL = ,'-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.

Inorganic Salts of -phenylbiguanidium(1+)-Novel Family with Promising Representatives for Nonlinear Optics.

Seven inorganic salts containing -phenylbiguanide as a prospective organic molecular carrier of nonlinear optical properties were prepared and studied within our research of novel hydrogen-bonded materials for nonlinear optics (NLO). All seven salts, namely -phenylbiguanidium(1+) nitrate (2/), -phenylbiguanidium(1+) perchlorate (-1), -phenylbiguanidium(1+) hydrogen carbonate (2/), bis(-phenylbiguanidium(1+)) sulfate (2), bis(-phenylbiguanidium(1+)) hydrogen phosphate sesquihydrate (-1), bis(-phenylbiguanidium(1+)) phosphite (2), and bis(-phenylbiguanidium(1+)) phosphite dihydrate (2/), were characterised by X-ray diffraction (powder and single-crystal X-ray diffraction) and by vibrational spectroscopy (FTIR and Raman). Two salts with non-centrosymmetric crystal structures-bis(-phenylbiguanidium(1+)) sulfate and bis(-phenylbiguanidium(1+)) phosphite-were further studied to examine their linear and nonlinear optical properties using experimental and computational methods.

From tetranuclear to pentanuclear [Co-Ln] (Ln = Gd, Tb, Dy, Ho) complexes across the lanthanide series: effect of varying sequence of ligand addition.

Two new families of cobalt(ii/iii)-lanthanide(iii) coordination aggregates have been reported: tetranuclear [LnCoL(N-BuDEA)(OCCMe)(HO)]·(MeOH)·(HO) (Ln = Gd, 1; Tb, 2; Dy, 3; n = 2, m = 10 for 1 and 2; n = 6, m = 2 for 3) and pentanuclear LnCoCoL(N-BuDEA)(OCCMe)(MeOH) (Ln = Dy, 4; Ho, 5) formed from the reaction of two aggregation assisting ligands HL (o-vanillin oxime) and N-BuDEAH (N-butyldiethanolamine). A change in preference from a lower to higher nuclearity structure was observed on going across the lanthanide series brought about by the variation in the size of the Ln ions. An interesting observation was made for the varying sequence of addition of the ligands into the reaction medium paving the way to access both structural types for Ln = Dy.

Solvent-induced structural transformation from heptanuclear to decanuclear [Co-Ln] coordination clusters: trapping of unique counteranion and understanding of aggregation pathways.

Five new cobalt(ii/iii)-lanthanide(iii)-based coordination aggregates, [LnIII3CoII2CoIII2(L1)2(O2CCMe3)8(OH)4(OMe)2(H2O)4]·Ln(η1-O2CCMe3)2(η2-O2CCMe3)2(MeOH)2·2MeOH·2H2O (where Ln = Tb (1), Ho (3), and H2L1 = N-(2-hydroxyethyl)-salicylaldimine), TbIII3CoII3CoIII4(L1)4(O2CCMe3)9(OH)10(H2O) (4) and LnIII3CoII2CoIII5(L1)4(O2CCMe3)10(OH)10 (Ln = Dy (5), Ho (6)) have been synthesized and characterized, including structural analysis via single-crystal X-ray diffraction. The dysprosium analogue (2) of 1 and 3 was previously reported by us. The heptanuclear monocationic clusters in 1 and 3 were formed by placement of seven metal ions (4 Co and 3 Ln) in a vertex shared dicubane structure from the control of two Schiff base anions and crystallized in the presence of in situ generated and literature unknown counter anions Tb(η1-O2CCMe3)2(η2-O2CCMe3)2(MeOH)2- and Ho(η1-O2CCMe3)2(η2-O2CCMe3)2(MeOH)2-.

Unexpected solution behaviour of ester-functionalized half-sandwich Ru(II) and Ir(III) complexes.

Complexes [Ru(η6-pcym)(bpydca)Cl]PF6 (Rudca) and [Ir(η5-Cp*)(bpydca)Cl]PF6 (Irdca) were developed as model compounds for the investigation of multi-targeted ester-functionalized half-sandwich ruthenium(ii) and iridium(iii) complexes; pcym = 1-methyl-4-(propan-2-yl)benzene (p-cymene), bpydca = 2,2'-bipyridine-4,4'-diyldimethanediyl bis(dichloroacetate), Cp* = pentamethylcyclopentadienyl. Aiming to understand the in-solution behaviour of these first-in-class complexes containing the pyruvate dehydrogenase kinase inhibitor dichloroacetate (dca) as the terminal bioactive substituent, several experiments were performed under aqueous conditions for Rudca and Irdca, as well as for compounds [Ru(η6-pcym)(bpyOH)Cl]PF6 (RuOH) and [Ir(η5-Cp*)(bpyOH)Cl]PF6 (IrOH), and acetyl analogues [Ru(η6-pcym)(bpyac)Cl]PF6 (Ruac) and [Ir(η5-Cp*)(bpyac)Cl]PF6 (Irac) bearing a different (biologically inactive) terminal substituent; bpyOH = 2,2'-bipyridine-4,4'-diyldimethanol, bpyac = 2,2'-bipyridine-4,4'-diyldimethanediyl diacetate. The experiments were also conducted in the presence of porcine liver esterase (PLE).

Deposition of Tetracoordinate Co(II) Complex with Chalcone Ligands on Graphene.

Studying the properties of complex molecules on surfaces is still mostly an unexplored research area because the deposition of the metal complexes has many pitfalls. Herein, we probed the possibility to produce surface hybrids by depositing a Co(II)-based complex with chalcone ligands on chemical vapor deposition (CVD)-grown graphene by a wet-chemistry approach and by thermal sublimation under high vacuum Samples were characterized by high-frequency electron spin resonance (HF-ESR), XPS, Raman spectroscopy, atomic force microscopy (AFM), and optical microscopy, supported with density functional theory (DFT) and complete active space self-consistent field (CASSCF)/N-electron valence second-order perturbation theory (NEVPT2) calculations. This compound's rationale is its structure, with several aromatic rings for weak binding and possible favorable - stacking onto graphene.

The red and blue luminescence in silicon nanocrystals with an oxidized, nitrogen-containing shell.

Traditionally, two classes of silicon nanocrystals (SiNCs) are recognized with respect to their light-emission properties. These are usually referred to as the "red" and the "blue" emitting SiNCs, based on the spectral region in which the larger part of their luminescence is concentrated. The origin of the "blue" luminescence is still disputed and is very probably different in different systems.

Heteronuclear Iron(III)-Schiff Base Complexes with the Hexacyanidocobaltate(III) Anion: On the Quest To Understand the Governing Factors of Spin Crossover.

Two heteronuclear compounds ( and ) containing three ferric centers linked in facial-like mode with the magnetically silent hexacyanidocobaltate(III) anion were prepared and studied. The structural investigation revealed that both compounds are tetranuclear complexes with molecular formulas of [{Fe(L1)NC}Co(CN)]·2CHOH·2.5CHCN () and [{Fe(L2)NC}Co(CN)]·2HO·1CHOH ().

Structural and magnetic characterization of Ni(ii), Co(ii), and Fe(ii) binuclear complexes on a bis(pyridyl-triazolyl)alkane basis.

Reactions of bis[5-(2-pyridyl)-1,2,4-triazol-3-yl]alkanes (alkane spacers = -CH2- in L2, -C3H6- in L3, -C4H8- in L4) with M(ii)A2 salts (M = Ni, Co, Fe) resulted in the preparation of five series of mononuclear ([M(L2)(H2O)2]2+, 1a-c) or binuclear ([M2(L3)2(H2O)4]4+, 2a-c; ([M2(L4)2(H2O)4]4+, 3a-c, [M2(L3)2(μ-ox)]2+, 4a-c; [M2(L4)2(μ-ox)]2+, 5a-c) complexes. The crystal structures of ten complexes were determined by single-crystal X-ray crystallography. Magnetic properties of the compounds were characterized by SQUID magnetometry and were analyzed by fitting on a spin Hamiltonian model.