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Student publication in Dalton Transactions

Journal cover 15. June 2021

Publication entitled "Unexpected solution behaviour of ester-functionalized half-sandwich Ru(II) and Ir(III) complexes" (authors: L. Masaryk, I. Nemec, J. Kašpárková, V. Brabec, P. Štarha) has been published in the chemistry journal Dalton Transactions.

In this work, we studied the solution behaviour of two half-sandwich Ru(II) and Ir(III) complexes bearing the ester-functionalized 2,2′-bipyridine-based ligand. It was proved that the nature of ester substituent (acetate vs. dichloroacetate) affects the in-solution stability of the ester bond. The experiments performed in the presence of porcine liver esterase (PLE) indicated that although free ester-based ligand was readily metabolized by PLE (acetate release was observed), both complexes containing this ligand were not cleaved by PLE, meaning distinctly different affinity of the used enzyme to the substrate (ligand) when involved in the studied complexes.

Publication in Dalton Transactions

Journal cover09. June 2021

Publication entitled "Thermo- and photoinduced spin state switching in an iron(ii) 2D coordination network associated with large light-induced thermal hysteresis and tuning of dimensionality via ligand modulation" (authors: S. Ghosh, S. Kamilya, T. Pramanik, A. Mohanty, M. Rouzières, R. Herchel, S. Mehta, A. Mondal ) has been published in the chemistry journal Dalton Transactions.

In this work, three Fe(II) coordination compounds were investigated, while by examining the magnetic properties of [Fe(L2)2(NCS)2]n (3) (L2 = 2,5-diethynylpyridinyl-3,4- ethylenedioxythiophene) it was confirmed that the change in spin state is caused by the change in temperature, i.e. it is a spin crossover compound. Photomagnetic experiments confirmed the possibility of switching the spin state even by exposure to light. The study was also supported by theoretical calculations such as DFT, TD-DFT and CASSCF explaining the magnetic and spectroscopic properties of these substances.

Student publication in Polyhedron as cover

Journal cover31. May 2021

Publication entitled "Triple M as Manganese: Medicine, magnetism and macrocycles. Seven-coordinate Mn(II) complexes with pyridine-based macrocyclic ligands" (authors: E. Zahradníková, I. Císařová, B. Drahoš) has been published in the chemistry journal Polyhedron. Moreover, the picture describing this work was chosen as a cover artwork for the corresponding issue of the jurnal.

In this work, 3 structurally new ligands L1-L3 derived from a 17-membered macrocyclic ligand with pyridine and piperazine group and their manganese complexes were prepared. Based on the results of X-ray structural analysis, the prepared complexes were found as seven-coordinate with close to the pentagonal bipyramidal geometry. The Mn-Naliphatic bond distances in the equatorial plane were significantly lengthened up to 2.61Å.

Publication in Dalton Transactions

Journal cover12. May 2021

Publication entitled "An unexpected in-solution instability of diiodido analogue of picoplatin complicates its biological characterization" (authors: P. Štarha, B. Drahoš, R. Herchel) has been published in the chemistry journal Dalton Transactions.

In this work, we investigated the solution behaviour of biologically prospective complex cis-[PtI2(NH3)(pic)] (pic = 2-methylpyridine), a diiodido analogue of clinically studied Pt-based drug picoplatin (cis-[PtCl2(NH3)(pic)]). We proved both experimentally and theoretically that cis‑[PtI2(NH3)(pic)] is, in contrast to picoplatin, unstable in solution, where it undergoes several processes, including the release of its N-donor pic ligand. This observation complicates the cytotoxicity testing of this Pt(II) diiodido complex.

Publication in Dalton Transactions

Journal cover19. April 2021

Publication entitled "Hydroxido supported and differently networked octanuclear Ni6Ln2 [Ln = GdIII and DyIII] complexes: structural variation, magnetic properties and theoretical insights" (authors: A. Bhanja, L. Smythe, R. Herchel, I. Nemec, M. Murrie, D. Ray) has been published in the chemistry journal Dalton Transactions.

In this work, the magnetic properties of two hexanuclear coordination compounds [Gd2Ni6L43-OH)6(μ-OH)2(CH3CO2)2(μ-H2O)2(H2O)3(MeOH)]·8H2O (1) and [Dy2Ni6L43-OH)4(μ-Cl)2Cl4(H2O)2(MeOH)2]·2MeOH·4H2O (2) prepared with the same ligand - Schiff base H2L = 2 - {[(2-hydroxy-3-methoxybenzyl) imino] methyl} phenol, were investigated. Inspection of the magnetic properties revealed a dominant ferromagnetic exchange interaction in compound 1 and compound 2 was identified as a single molecule magnet. The study was supported by theoretical calculations such as DFT and CASSCF leading to the elucidation of exchange interactions and magnetic anisotropy in these complexes.

Publication in Coordination Chemistry Reviews

Journal cover10. February 2021

Publication entitled "Multinuclear biologically active Ru, Rh, Os and Ir arene complexes" (author: P. Štarha) has been published in the chemistry journal Coordination Chemistry Reviews.

In this review, multinuclear biologically active complexes derived from half-sandwich ruthenium(II), rhodium (III), osmium(II) and iridium(III) arene moieties have been reported. Besides homometallic Ru, Rh, Os and Ir complexes, heterometallic compounds containing the mentioned platinum metals in combination with other d-block elements are discussed as well. Special attention was paid to the comparison of structurally similar analogues differing in the number or type of metal centres.

Publication in Inorganic Chemistry

Journal cover15. December 2020

Publication entitled "Reversible Spin-State Switching and Tuning of Nuclearity and Dimensionality via Nonlinear Pseudohalides in Cobalt(II) Complexes" (authors: S. Ghosh, S. Kamilya, M. Rouzières, R. Herchel, S. Mehta, A. Mondal ) has been published in the chemistry journal Inorganic Chemistry.

Herein, we report on investigations of magnetic, spectroscopic and electrochemical properties of two Co(II) coordination compounds with N,N-di-tert-butyl-2,11-diaza[3,3](2,6)pyridinophane macrocyclic ligand. Complex 1 exhibits a high-spin (S = 3/2) state of cobalt(II) with a large magnetic anisotropy. Interestingly, complex 2 exhibits reversible spin-state switching (T1/2 = 321 K).

Publication in Dalton Transactions

Journal cover29. October 2020

Publication entitled "From solid state to in vitro anticancer activity of copper(II) compounds with electronically-modulated NNO Schiff base ligands" (authors: L. Rigamonti, F. Reginato, E. Ferrari, L. Pigani, L. Gigli, N. Demitri, P. Kopel, B. Tesarova, Z. Heger) has been published in the chemistry journal Dalton Transactions.

The copper(II) complexes of general formula [Cu(GL)(Cl)] (13, G = OMe, H and NO2, respectively), bearing tridentate Schiff base ligands (GL) and a chloride as a fourth labile one, are here reported. The Schiff bases derive from the monocondensation of ethylenediamine and substituted salicylaldehyde, where the electronic properties are modulated by the releasing or withdrawing power of the G group. The compounds were structurally characterized through single crystal Synchrotron X-ray diffraction experiments in the solid state. In vitro tests on cell viability were conducted on malignant cell lines. All compounds were capable of formation of intracellular reactive oxygen species and DNA intercalation. This is especially effective for 3 (NO2), which revealed the highest anticancer activity against malignant triple-negative breast cancer MDA-MB-231 cells.

Publication in Nanomaterials

29. October 2020

Publication entitled "Synergistic Effect of Chitosan and Selenium Nanoparticles on Biodegradation and Antibacterial Properties of Collagenous Scaffolds Designed for Infected Burn Wounds" (authors: J. Dorazilová, J. Muchová, K. Šmerková, S. Kočiová, P. Diviš, P. Kopel, R. Veselý, V. Pavliňáková, V. Adam, L. Vojtová) has been published in the journal Nanomaterials.

A highly porous scaffold is a desirable outcome in the field of tissue engineering. The porous structure mediates water-retaining properties that ensure good nutrient transportation as well as creates a suitable environment for cells. In this study, porous antibacterial collagenous scaffolds containing chitosan and selenium nanoparticles (SeNPs) as antibacterial agents were studied. The addition of antibacterial agents increased the application potential of the material for infected and chronic wounds. The morphology, swelling, biodegradation, and antibacterial activity of collagen-based scaffolds were characterized systematically to investigate the overall impact of the antibacterial additives. The additives visibly influenced the morphology, water-retaining properties as well as the stability of the materials in the presence of collagenase enzymes. Even at concentrations as low as 5 ppm of SeNPs, modified polymeric scaffolds showed considerable inhibition activity towards Gram-positive bacterial strains such as Staphylococcus aureus and methicillin-resistant S. aureus and S. epidermidis.

Publication in Dalton Transactions

10. September 2020

Publication entitled " Co(ii)-Based single-ion magnets with 1,1′-ferrocenediyl-bis(diphenylphosphine) metalloligands" (authors: J. Hrubý, D. Dvořák, L. Squillantini, M. Mannini, J. van Slageren, R. Herchel, I. Nemec, P. Neugebauer ) has been published in the chemistry journal Dalton Transactions.

Herein, we report on investigations of magnetic and spectroscopic properties of three heterobimetallic Fe(II)–Co(II) coordination compounds based on the tetracoordinate {CoP2X2} core encapsulated by dppf metalloligand, where X = Cl (1), Br (2), I (3), dppf = 1,1′-ferrocenediyl -bis(diphenylphosphine). The analysis of static magnetic data has revealed the presence of axial magnetic anisotropy in compounds (1) and (2) and this was further confirmed by high-frequency electron spin resonance (HF-ESR) spectroscopy. Dynamic magnetic data confirmed that (1) and (2) behave as field-induced Single-Ion Magnets (SIMs). Together with bulk studies, we have also tested the possibility of depositing (2) as thick films on Au(111), glass, and polymeric acetate by drop-casting as well as thermal sublimation, a key aspect for the development of future devices embedding these magnetic objects.

Endowment Fund of Palacký University supported our student

17. july 2020

Ph.D. student of Inorganic Chemie Mgr. Marie Pražáková received a finantial support from Endowment fung of Palacky University.

Mgr. Marie Pražáková, a first-year doctoral student in Inorganic Chemistry, succeeded and received a financial support from the UP Endowment Fund, which will be very beneficial for solving her research project called Research of Contrast Agents for MRI (Magnetic Resonance Imaging).

More details can be found on the webpage of the Faculty of Science or UP Endowment Fund.

Congratulations to Marie and we wish her much success in solving the project.

(Mgr. Pražáková second from the right)

Publication in Dalton Transactions

8. july 2020

Publication entitled "Late first-row transition metal complexes of a 17-membered piperazine-based macrocyclic ligand: structures and magnetism." (authors: E. Zahradníková, R. Herchel, I. Šalitroš, I. Císařová, B. Drahoš) has been published in the chemistry journal Dalton Transactions.

The 17-membered piperazine-based macrocyclic ligand LdiProp (1,5,13,17,22-pentaazatricyclo[15.2.2.17,11]docosa-7,9,11(22)-triene) was resynthesized in high yield with help of linear pump. Its Mn(II), Fe(II), Co(II) and Ni(II) complexes of general formula [MnLdiProp(ClO4)2] (1), [FeLdiProp(CH3CN)](ClO4)2 (2), [CoLdiProp(CH3CN)](ClO4)2 (3), [NiLdiProp](ClO4)2 (4) were prepared and thoroughly characterized. X-ray diffraction analysis confirmed that Mn(II) complex 1 has capped trigonal prismatic geometry with coordination number seven, Fe(II) and Co(II) complexes 2 and 3 are trigonal prismatic with coordination number six and Ni(II) complex 4 has square pyramidal geometry with coordination number five. The decrease of coordination number is accompanied by a shortening of M–N distances and an increase of torsion of piperazine ring from the equatorial plane. Magnetic measurement reveal moderate for 4 and rather large magnetic anisotropy for 2 and 3 (axial zero-field splitting parameter D(Ni) = 9.0 cm–1, D(Fe) = –14.4 cm–1, D(Co) = –25.8 cm–1, together with rather high rhombicity). Co(II) complex 3 behaves as field-induced SMM with a combination of Raman and direct or Orbach and direct relaxation mechanisms. Obtained magnetic data were extensively supported by theoretical CASSCF calculations. The flexibility and rather large 17-membered macrocyclic cavity of ligand LdiProp could be responsible for the variation of coordination numbers and geometries for investigated late-first row transition metals.