Publications by authors named "Sergiu Shova"

96 Publications

Coumarin-Based Triapine Derivatives and Their Copper(II) Complexes: Synthesis, Cytotoxicity and mR2 RNR Inhibition Activity.

Biomolecules 2021 Jun 9;11(6). Epub 2021 Jun 9.

Institute of Inorganic Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, Austria.

A series of thiosemicarbazone-coumarin hybrids ( and ) has been synthesised in 12 steps and used for the preparation of mono- and dinuclear copper(II) complexes, namely (), (), () and (), isolated in hydrated or solvated forms. Both the organic hybrids and their copper(II) and dicopper(II) complexes were comprehensively characterised by analytical and spectroscopic techniques, i.e., elemental analysis, ESI mass spectrometry, 1D and 2D NMR, IR and UV-vis spectroscopies, cyclic voltammetry (CV) and spectroelectrochemistry (SEC). Re-crystallisation of from methanol afforded single crystals of copper(II) complex with monoanionic ligand , which could be studied by single crystal X-ray diffraction (SC-XRD). The prepared copper(II) complexes and their metal-free ligands revealed antiproliferative activity against highly resistant cancer cell lines, including triple negative breast cancer cells MDA-MB-231, sensitive COLO-205 and multidrug resistant COLO-320 colorectal adenocarcinoma cell lines, as well as in healthy human lung fibroblasts MRC-5 and compared to those for triapine and doxorubicin. In addition, their ability to reduce the tyrosyl radical in mouse R2 protein of ribonucleotide reductase has been ascertained by EPR spectroscopy and the results were compared with those for triapine.
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http://dx.doi.org/10.3390/biom11060862DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8230303PMC
June 2021

Synthesis of 1-(2-Fluorophenyl)pyrazoles by 1,3-Dipolar Cycloaddition of the Corresponding Sydnones.

Molecules 2021 Jun 17;26(12). Epub 2021 Jun 17.

Center of Organic Chemistry ''C. D. Nenitzescu'', Roumanian Academy, Spl Independentei 202B, 060023 Bucharest, Romania.

3-Arylsydnones bearing fluorine and bromine atoms on the benzene ring were synthesized from -nitroso-2-fluorophenylglycines and characterized by NMR spectroscopy. These were employed further in synthesis of the corresponding 1-(2-fluorophenyl)pyrazoles by 1,3-dipolar cycloaddition reaction with dimethyl acetylenedicarboxylate (DMAD) as activated dipolarophile. The sydnones as reaction intermediates were characterized by single crystal X-ray diffraction analysis showing interesting features such as halogen bonding as an important interaction in modeling the crystal structure.
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http://dx.doi.org/10.3390/molecules26123693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8235238PMC
June 2021

Spin crossover in iron(II) Hofmann clathrates analogues with 1,2,3-triazole.

Dalton Trans 2021 Jul;50(26):9250-9258

Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska St. 64, Kyiv 01601, Ukraine. and UkrOrgSyntez Ltd, Chervonotkatska St. 67, Kyiv 02094, Ukraine.

Hofmann-like cyanometallic complexes represent one of the biggest and well-known classes of FeII spin-crossover compounds. In this paper, we report on the first FeII Hofmann clathrate analogues with unsubstituted 1,2,3-triazole, which exhibit temperature induced spin transition. Two new coordination polymers with the general formula [FeII(1,2,3-triazole)2MII(CN)4] (M = Pt, Pd) undergo abrupt hysteretic spin crossover in the range of 190-225 K as revealed by magnetic susceptibility measurements. Two compounds are isostructural and are built of infinite cyanometallic layers which are supported by 1,2,3-triazole ligands. The thermal hysteresis loop is very stable at different scan rates from 0.5 to 10 K min-1. The compounds display strong thermochromic effect, changing their colour from pink in the low-spin state to white in the high-spin state. Our findings show that 1,2,3-triazole is suitable for elaboration of spin-crossover Hofmann clathrate analogues, and its use instead of more classical azines can advantageously expand this family of complexes.
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http://dx.doi.org/10.1039/d1dt01544cDOI Listing
July 2021

Crystal structure of { , -bis-[(1--butyl-1-1,2,3-triazol-4-yl)methyl-idene]-2,2-di-methyl-propane-1,3-di-amine}-bis-(thio-cyanato)-iron(II).

Acta Crystallogr E Crystallogr Commun 2021 May 30;77(Pt 5):573-578. Epub 2021 Apr 30.

The Faculty of Physics, Tajik National University, Rudaki Avenue 17, Dushanbe, 734025, Tajikistan.

The unit cell of the title compound, [Fe(NCS)(CHN)], consists of two charge-neutral complex mol-ecules. In the complex mol-ecule, the tetra-dentate ligand -bis-[(1--butyl-1-1,2,3-triazol-4-yl)methyl-ene]-2,2-di-methyl-propane-1,3-di-amine coordinates to the Fe ion through the N atoms of the 1,2,3-triazole and aldimine groups. Two thio-cyanate anions, also coordinated through their N atoms, complete the coordination sphere of the central Fe ion. In the crystal, neighbouring mol-ecules are linked through weak C-H⋯C/S/N inter-actions into a three-dimensional network. The inter-mol-ecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 50.8%, H⋯C/C⋯H 14.3%, H⋯S/S⋯H 20.5% and H⋯N/N⋯H 12.1%. The average Fe-N bond distance is 2.170 Å, indicating the high-spin state of the Fe ion, which does not change upon cooling, as demonstrated by low-temperature magnetic susceptibility measurements. DFT calculations of energy frameworks at the B3LYP/6-31 G(d,p) theory level were performed to account for the inter-actions involved in the crystal structure.
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http://dx.doi.org/10.1107/S2056989021004412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8100266PMC
May 2021

Crystal structure of ( , -bis-{[1-(4-meth-oxy-benz-yl)-1-1,2,3-triazol-4-yl]methyl-idene}-2,2-di-meth-yl-propane-1,3-di-amine)-bis-(thio-cyanato)-iron(II).

Acta Crystallogr E Crystallogr Commun 2021 May 9;77(Pt 5):495-499. Epub 2021 Apr 9.

The Faculty of Physics, Tajik National University, Rudaki Avenue 17, Dushanbe, 734025, Tajikistan.

The unit cell of the title compound, [Fe(NCS)(CHNO)], consists of eight charge-neutral complex mol-ecules. In the complex mol-ecule, the tetra-dentate ligand , -bis-{[1-(4-meth-oxy-benz-yl)-1-1,2,3-triazol-4-yl]methyl-ene}-2,2-di-methyl-propane-1,3-di-amine coordinates to the Fe ion through the N atoms of the 1,2,3-triazole and aldimine groups. Two thio-cyanate anions, coordinated through their N atoms, complete the coordination sphere of the central Fe ion. In the crystal, neighbouring mol-ecules are linked through weak C⋯C, C⋯N and C⋯S inter-actions into a one-dimensional chain running parallel to [010]. The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H (37.5%), H⋯C/C⋯H (24.7%), H⋯S/S⋯H (15.7%) and H⋯N/N⋯H (11.7%). The average Fe-N bond distance is 2.167 Å, indicating the high-spin state of the Fe ion, which does not change upon cooling, as demonstrated by low-temperature magnetic susceptibility measurements.
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http://dx.doi.org/10.1107/S2056989021003662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8100278PMC
May 2021

Crystal structure of { , -bis-[(1-benzyl-1-1,2,3-triazol-4-yl)methyl-idene]-2,2-di-methyl-propane-1,3-di-amine}bis-(thio-cyanato-κ)iron(II).

Acta Crystallogr E Crystallogr Commun 2020 Oct 22;76(Pt 10):1661-1664. Epub 2020 Sep 22.

Department of General and Inorganic Chemistry, Faculty of Chemistry, Tajik State Pedagogical University, Rudaki 121, 734003 Dushanbe, Tajikistan.

The unit cell of the title compound, [Fe(NCS)(CHN)], consists of two charge-neutral complex mol-ecules related by an inversion centre. In the complex mol-ecule, the tetra-dentate ligand , -bis-[(1-benzyl-1-1,2,3-triazol-4-yl)methyl-ene]-2,2-di-methyl-propane-1,3-di-amine coordinates to the Fe ion through the N atoms of the 1,2,3-triazole moieties and aldimine groups. Two thio-cyanate anions, coordinating through their N atoms, complete the coordination sphere of the central ion. In the crystal, neighbouring mol-ecules are linked through weak C-H⋯π, C-H⋯S and C-H⋯N inter-actions into a two-dimensional network extending parallel to (011). The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H (35.2%), H⋯C/C⋯H (26.4%), H⋯S/S⋯H (19.3%) and H⋯N/N⋯H (13.9%).
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http://dx.doi.org/10.1107/S2056989020012608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534255PMC
October 2020

Crystal structure of bis-{μ-2-[bis-(2-hy-droxy-eth-yl)amino]-ethano-lato}bis-(μ-3,5-di-methyl-pyrazolato)tricopper(II) dibromide sesquihydrate.

Acta Crystallogr E Crystallogr Commun 2020 Oct 11;76(Pt 10):1641-1644. Epub 2020 Sep 11.

Department of Chemistry, Tajik National University, 17, Rudaki Avenue, Dushanbe, 734025, Tajikistan.

In the title bicyclic trinuclear pyrazolate amino-alcohol complex, [Cu(CHN)(CHNO)]Br·1.5HO, the central Cu atom lies on a center of symmetry and is involved in the formation of two five-membered rings. It has a coordination number of 4, is in a distorted tetra-hedral environment and is connected by the bridging oxygen atoms of the deprotonated OH groups of different amino-alcohol groups, and by the N atoms of deprotonated di-methyl-pyrazole ligands. The peripheral Cu atom is in a trigonal-bipyramidal coordination environment formed by the nitro-gen atom of the deprotonated bridging di-methyl-pyrazole unit, the bridging oxygen atom of the deprotonated OH group, two oxygen atoms of the protonated hy-droxy groups and the nitro-gen atom of tri-ethano-lamine. One of the C atoms and the Br anion were found to be disordered over two positions with occupancy factors of 0.808 (9):0.192 (9) and 0.922 (3):0.078 (3), respectively.
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http://dx.doi.org/10.1107/S2056989020012323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534225PMC
October 2020

Crystal structure of di-chlorido-1κ,2κ-(μ-3,5-dimethyl-1-pyrazolato-1κ :2κ )(3,5-dimethyl-1-pyrazole-2κ ){μ-2-[(2-hy-droxy-eth-yl)amino-1κ ,]ethano-lato-1:2κ :}dicopper(II).

Acta Crystallogr E Crystallogr Commun 2020 Sep 25;76(Pt 9):1503-1507. Epub 2020 Aug 25.

Department of Chemistry, Tajik National University, 17, Rudaki Avenue, Dushanbe, 734025, Tajikistan.

The title compound, [Cu(CHN)(CHNO)Cl(CHN)], is a pyrazolate amino-alcohol complex which contains two di-methyl-pyrazole mol-ecules in monodentate and bidentate-bridged coordination modes and a monodeproton-ated di-ethano-lamine mol-ecule. Both copper atoms are involved in the formation of non-planar five-membered chelate rings. One Cu atom is in a distorted tetra-hedral environment formed by the pyridine nitro-gen atom of the protonated di-methyl-pyrazole mol-ecule, the N atom of the deprotonated bridged di-methyl-pyrazole, the Cl atom and the bridged O atom of the monodeprotonated di-ethano-lamine. The second Cu atom has an inter-mediate environment between trigonal bipyramidal and square pyramidal, formed by the N atom of the deprotonated bridged di-methyl-pyrazole, the Cl atom and the N atom of the amino-alcohol, and two O atoms of the deprotonated and protonated OH groups. In the crystal, N-H⋯Cl hydrogen bonds link the molecules into anti-symmetric chains running along the -axis direction. Adjacent chains are connected by O-H⋯O hydrogen bonds involving the hydroxyl group as donor.
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http://dx.doi.org/10.1107/S2056989020011184DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7472753PMC
September 2020

Insight into the Anticancer Activity of Copper(II) 5-Methylenetrimethylammonium-Thiosemicarbazonates and Their Interaction with Organic Cation Transporters.

Biomolecules 2020 08 20;10(9). Epub 2020 Aug 20.

Institute of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, Austria.

A series of four water-soluble salicylaldehyde thiosemicarbazones with a positively charged trimethylammonium moiety ([HL]Cl, R = H, Me, Et, Ph) and four copper(II) complexes [Cu(HL)Cl]Cl (-) were synthesised with the aim to study (i) their antiproliferative activity in cancer cells and, (ii) for the first time for thiosemicarbazones, the interaction with membrane transport proteins, specifically organic cation transporters OCT1-3. The compounds were comprehensively characterised by analytical, spectroscopic and X-ray diffraction methods. The highest cytotoxic effect was observed in the neuroblastoma cell line SH-5YSY after 24 h exposure and follows the rank order: > > > > >>[HL]Cl. The copper(II) complexes showed marked interaction with OCT1-3, comparable to that of well-known OCT inhibitors (decynium 22, prazosin and corticosterone) in the cell-based radiotracer uptake assays. The work paves the way for the development of more potent and selective anticancer drugs and/or OCT inhibitors.
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http://dx.doi.org/10.3390/biom10091213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7565988PMC
August 2020

New Microporous Lanthanide Organic Frameworks. Synthesis, Structure, Luminescence, Sorption, and Catalytic Acylation of 2-Naphthol.

Molecules 2020 Jul 3;25(13). Epub 2020 Jul 3.

Institut für Anorganische Chemie und Strukturchemie, Heinrich-Heine Universität Düsseldorf, Universitätsstr. 1, D 40225 Düsseldorf, Germany.

New metal-organic frameworks (MOF) with lanthanum(III), cerium(III), neodymium(III), europium(III), gadolinium(III), dysprosium(III), and holmium(III)] and the ligand precursor tris(-carboxyphenyl)--trimethylbenzene (HL) were synthesized under solvothermal conditions. Single crystal x-ray analysis confirmed the formation of three-dimensional frameworks of [LnL(HO)]·xDMF·yHO for Ln = La, Ce, and Nd. From the nitrogen sorption experiments, the compounds showed permanent porosity with Brunauer-Emmett-Teller (BET) surface areas of about 400 m/g, and thermal stability up to 500 °C. Further investigations showed that these Ln-MOFs exhibit catalytic activity, paving the way for potential applications within the field of catalysis.
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http://dx.doi.org/10.3390/molecules25133055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411860PMC
July 2020

Crystal structure of -poly[[[di-aqua-[1,2-bis(pyridin-4-yl)ethene]{4-[2-(pyridin-4-yl)ethen-yl]pyridinium}gold(I)iron(II)]-di-μ-cyanido] bis-[dicyanido-gold(I)] 1,2-bis-(pyridin-4-yl)ethene dihydrate].

Acta Crystallogr E Crystallogr Commun 2020 Jun 29;76(Pt 6):944-947. Epub 2020 May 29.

Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska St. 64, Kyiv 01601, Ukraine.

In the title compound [Fe(bpe)(Hbpe)Au(CN)][Au(CN)]·bpe·2HO} [where bpe = 1,2-bis-(pyridin-4-yl)ethene, CHN], the Fe ion is coordinated in a distorted octa-hedral [FeNO] environment by two di-cyano-aurate anions, two water mol-ecules and two partially protonated 1,2-di(4-pyrid-yl)ethyl-ene mol-ecules. Di-cyano-aurate anions bridge the Fe cations, forming infinite chains, which propagate along the axis direction. The chains are connected aurophilic inter-actions with two non-coordinated di-cyano-aurate anions for each Fe ion. The polymeric chains inter-act with each other π-π stacking between the guest bpe mol-ecules and multiple hydrogen bonds.
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http://dx.doi.org/10.1107/S2056989020006738DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7274000PMC
June 2020

Crystal structure of the one-dimensional coordination polymer formed by the macrocyclic [Ni(cyclam)] cation and the dianion of di-phenyl-silanediylbis(4-benzoic acid).

Acta Crystallogr E Crystallogr Commun 2020 Jun 29;76(Pt 6):929-932. Epub 2020 May 29.

L.V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kyiv 03028, Ukraine.

The asymmetric unit of the title compound, -poly[[[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ , , , )nickel(II)]-μ-4,4'-(di-phenyl-silanedi-yl)dibenz-o-ato-κ :'] sesquihydrate], {[Ni(CHOSi)(CHN)]·1.5HO} , consists of the halves of the centrosymmetric macrocyclic cation and the -symmetric di-carboxyl-ate dianion and of the water mol-ecule of crystallization. The Ni ion is coordinated by the four secondary N atoms of the macrocyclic ligand characterized by the most energetically favourable -III conformation and two mutually O atoms of the carboxyl-ate, forming a slightly tetra-gonally elongated -NO octa-hedron. The crystals are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] direction. Each polymeric chain is bonded to four neighbouring ones water mol-ecules providing O-H⋯O hydrogen bonds to the non-coordinated carboxyl O atoms to form a three-dimensional supra-molecular network.
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http://dx.doi.org/10.1107/S2056989020006544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7274011PMC
June 2020

A 2D coordination polymer assembled from a nickel(II) tetraazamacrocyclic cation and 4,4'-(dimethylsilanediyl)diphthalate(3-) linker.

Acta Crystallogr C Struct Chem 2020 May 20;76(Pt 5):419-426. Epub 2020 Apr 20.

L.V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kyiv 03028, Ukraine.

The preformed nickel(II) complex of the 14-membered macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane (cyclam, L), when treated with 4,4'-(dimethylsilanediyl)diphthalic acid (HA) in a DMF/HO mixture (4:1 v/v) under heating, leads to [Ni(L)](HA)·3DMF (I·DMF). Redissolution of this compound in a DMF/HO/MeOH mixture (4:1:30 v/v/v) with mild acidification under gentle heating results in the formation of a similar compound but containing water and methanol molecules of crystallization, [Ni(L)](HA)·5HO·2MeOH (II·HO). At lower temperature and concentration of reactants and longer reaction time, single crystals of composition {[{Ni(L)}(HA)]·4CHOH} (II·MeOH) were isolated. Single-crystal X-ray diffraction analysis of this compound, which, according to PXRD is isostructural with II·HO but different from I·DMF, revealed its two-dimensional (2D) polymeric structure, i.e. poly[[bis{μ-4-[(4-carboxy-3-carboxylatophenyl)dimethylsilyl]benzene-1,2-dicarboxylato-κO:O:O}tris(1,4,8,11-tetraazacyclotetradecane-κN)trinickel(II)] methanol tetrasolvate], {[Ni(CHOSi)(CHN)]·4CHOH}. It is built up of the monoprotonated tricarboxylate HA ligand coordinated in a monodentate manner in the axial positions of two crystallographically independent Ni cations, one of which is located on a crystallographic inversion centre. Both metal ions adopt a slightly tetragonally elongated trans-NO octahedral geometry. The compound has a lamellar structure with polymeric layers oriented parallel to the (10-2) plane, which are in turn linked via hydrogen bonds involving protonated carboxylic acid groups of the ligand. Bulk compounds I·DMF and II·HO were characterized by FT-IR and diffuse reflectance spectroscopy and thermogravimetry, which provide evidence of their structural differences.
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http://dx.doi.org/10.1107/S2053229620005008DOI Listing
May 2020

Electrically Driven Artificial Muscles Using Novel Polysiloxane Elastomers Modified with Nitroaniline Push-Pull Moieties.

ACS Appl Mater Interfaces 2020 May 8;12(20):23432-23442. Epub 2020 May 8.

Laboratory for Functional Polymers, Swiss Federal Laboratories for Materials Science and Technology Empa, Ueberlandstr. 129, CH-8600 Dübendorf, Switzerland.

The synthesis of novel dielectric elastomers that show a muscle-like actuation when exposed to a low electric field represents a major challenge in materials science. Silicone elastomers modified with polar side groups are among the most attractive dielectrics for such a purpose because of their high polarizability over a wide temperature and frequency range. Nitroaniline (NA) has a strong dipole moment, and therefore, its incorporation into silicone networks should allow the formation of elastomers with increased dielectric permittivity. However, incorporation of a large amount of NA into silicone needed to increase the dielectric permittivity is still challenging. In this work, we present the synthesis of polysiloxane elastomers modified with a large fraction of the nitroaniline (NA) polar group, following two different synthetic strategies. Both approaches allowed the formation of homogenous elastomers at the molecular level. These yellowish materials have a dielectric permittivity three times higher as compared to the reported NA-modified silicones. Additionally, they have excellent mechanical properties with low viscoelastic losses and a strain at break reaching 300%. Furthermore, the mechanical properties of these elastomers can be easily tuned by the content of cross-linkers used. The developed elastomers are highly stable in electromechanical tests and show an actuation strain of 8% at unprecedentedly low electric fields of 7.5 V/μm. The combination of properties such as high dielectric permittivity, large strain at break, low viscoelastic losses, fast and reversible actuation, and actuation at low electric fields is crucial for the new generation of dielectric elastomer materials that will find their way in applications ranging from artificial muscles, soft robots, sensors, and haptic displays to electronic skin.
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http://dx.doi.org/10.1021/acsami.0c03692DOI Listing
May 2020

Hofmann-Like Frameworks Fe(2-methylpyrazine)[M(CN)] (M = Au, Ag): Spin-Crossover Defined by the Precious Metal.

Inorg Chem 2020 May 17;59(9):6541-6549. Epub 2020 Apr 17.

Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska 64, 01601 Kyiv, Ukraine.

Hofmann-like cyanometalates constitute a large class of spin-crossover iron(II) complexes with variable switching properties. However, it is not yet clearly understood how the temperature and cooperativity of a spin transition are influenced by their structure. In this paper, we report the synthesis and crystal structures of the metal-organic coordination polymers {Fe(Mepz)[Au(CN)]} () and {Fe(Mepz)[Ag(CN)]} (), where Mepz = 2-methylpyrazine, along with characterization of their spin-state behavior by variable-temperature SQUID magnetometry and Mössbauer spectroscopy. The compounds are built of cyanoheterometallic layers, which are pillared by the bridging Mepz ligands in but separated in . The complex exhibits an incomplete stepped spin transition as a function of the temperature with = 170 K and = 308 K for the two subsequent steps. In contrast, the complex attains the high-spin state over the whole temperature range. In the crystal structure of , weak interlayer contacts (Ag-π, Me-π, and Ag-N) are found that may be responsible for an unusual axial elongation of the FeN polyhedra. We propose that this structural distortion contributes to the trapping of iron in its high-spin state.
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http://dx.doi.org/10.1021/acs.inorgchem.0c00627DOI Listing
May 2020

Spin crossover in 2D iron(ii) phthalazine cyanometallic complexes.

Dalton Trans 2020 Apr;49(16):5302-5311

Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine. and UkrOrgSyntez Ltd., 67 Chervonotkatska St., 02094 Kyiv, Ukraine.

Two new 2D spin-crossover (SCO) analogues of Hofmann clathrates of composition [Fe(phth)2MII(CN)4] (where phth = phthalazine; MII = Pd, Pt) have been synthesized and their structures and switchable behaviour have been characterized. Single-crystal X-ray analysis reveals that the Pt and Pd derivatives contain FeII centres equatorially surrounded by four equivalent μ4-[MII(CN)4]2- groups. Two crystallographically equivalent phthalazine (phth) ligands occupy the axial positions of each FeII site, completing its octahedral coordination environment. The stabilization of these structures is realized via supramolecular C-HM interactions and π-π stacking. Temperature-dependent magnetic susceptibility measurements showed that Pt (T1/2↓ = 211 K and T1/2↑ = 218 K) and Pd (T1/2↓ = 202 K and T1/2↑ = 207 K) derivatives display cooperative spin crossover with narrow thermal hysteresis loops. In addition, spin crossover in these complexes was characterized by optical measurements, differential scanning calorimetry, and IR and Raman spectroscopy. This research shows that the use of phthalazine leads to the production of new SCO systems with attractive transition characteristics and opens up new perspectives for the design of switchable complexes based on fused bicyclic azine ligands.
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http://dx.doi.org/10.1039/d0dt00783hDOI Listing
April 2020

Syntheses and crystal structures of the one-dimensional coordination polymers formed by [Ni(cyclam)] cations and 1,3-bis-(3-carb-oxy-prop-yl)tetra-methyl-disiloxane anions in different degrees of deprotonation.

Acta Crystallogr E Crystallogr Commun 2020 Mar 25;76(Pt 3):446-451. Epub 2020 Feb 25.

L.V. Pisarzhevskii Institute of Physical Chemistry of the National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kyiv 03028, Ukraine.

The asymmetric units of the title compounds, namely, -poly[[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ , , , )nickel(II)]-μ-1,3-bis-(3-carboxyl-ato-prop-yl)tetra-methyl-disiloxane-κ :'], [Ni(CHOSi)(CHN)] (), and -poly[[[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ , , , )nickel(II)]-μ-4-({[(3-carb-oxy-prop-yl)di-methyl-sil-yl]-oxy}di-methyl-sil-yl)butano-ato-κ :'] per-chlorate], {[Ni(CHOSi)(CHN)]ClO} (), consist of one (in ) or two crystallographically non-equivalent (in ) centrosymmetric macrocyclic cations and one centrosymmetric dianion (in ) or two centrosymmetric monoanions (in ). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable -III conformation, and the mutually O atoms of the carboxyl-ate in a slightly tetra-gonally distorted -NiNO octa-hedral coordination geometry. The crystals of both types of compounds are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] and [110] directions in and , respectively. In , each polymeric chain is linked to four neighbouring ones by hydrogen bonding between the NH groups of the macrocycle and the carboxyl-ate O atoms, thus forming a three-dimensional supra-molecular network. In , each polymeric chain contacts with only two neighbours, forming hydrogen bonds between the partially protonated carb-oxy-lic groups of the bridging ligand. As a result, a lamellar structure is formed with the layers oriented parallel to the (11) plane.
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http://dx.doi.org/10.1107/S2056989020002327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057376PMC
March 2020

Explaining How α-Hydroxamate Ligands Control the Formation of Cu(II)-, Ni(II)-, and Zn(II)-Containing Metallacrowns.

Inorg Chem 2019 Dec 21;58(24):16642-16659. Epub 2019 Nov 21.

Faculty of Chemistry , University of Wroclaw , 50-383 Wroclaw , Poland.

Four different crystal structures for quinolinehydroxamic acid () and picolinehydroxamic acid () MCs with Cu(II) and Ni(II), and solution studies on the formation of Cu(II), Ni(II), and Zn(II) MC complexes with , , and pyrazylohydroxamic acid () are described. In polynuclear complex , [Cu(-2H)(NO)(DMSO)](NO), the metallamacrocyclic cavity is formed by four Cu(II) ions and four doubly deprotonated hydroximate ligands, and the center of the cavity is occupied by the fifth Cu(II) ion coordinated by four hydroximate oxygen atoms. The complex , [Cu(-2H)(HO)(ClO)](ClO)·4HO, exhibits a dimeric structure based on two pentanuclear collapsed 12-MC-4 Cu(2H) fragments united by two chiral capping Cu(II) ions exo-coordinated to the peripheral vacant (O,O') chelating units of each tetranuclear collapsed MC moiety. , [CaNi(-2H)(HO)(Py)](NO), and , [CaNi(-2H)(DMF)(Py)](NO), are planar 15-membered rings consisting of a or ligand, respectively. To understand fully the correlation between species isolated in the solid state and those presented in solution, the solution equilibria were investigated, showing the dependence of the MCs topologies and stability constants (log β) on the ligand structure and metal ion.
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http://dx.doi.org/10.1021/acs.inorgchem.9b02724DOI Listing
December 2019

Crystal structure of poly[[di-aqua-tetra-μ-cyanido-iron(II)platinum(II)] acetone disolvate].

Acta Crystallogr E Crystallogr Commun 2019 Oct 27;75(Pt 10):1536-1539. Epub 2019 Sep 27.

Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska St. 64, Kyiv 01601, Ukraine.

In the title polymeric complex, {[FePt(CN)(HO)]·2CHO} , the Fe cation has an octa-hedral [FeNO] geometry being coordinated by two water mol-ecules and four cyanide anions. The Pt cation is located on an inversion centre and has a square-planar coordination environment formed by four cyanide groups. The tetra-cyano-platinate anions bridge the Fe cations to form infinite two-dimensional layers that propagate in the plane. Two guest mol-ecules of acetone per Fe are located between the layers. These guest acetone mol-ecules inter-act with the coordinated water mol-ecules by O-H⋯O hydrogen bonds.
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http://dx.doi.org/10.1107/S2056989019012945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6775733PMC
October 2019

Crystal structure of -poly[[gold(I)-μ-cyanido-[di-aqua-bis-(2-phenyl-pyrazine)-iron(II)]-μ-cyanido] dicyanidogold(I)].

Acta Crystallogr E Crystallogr Commun 2019 Aug 12;75(Pt 8):1149-1152. Epub 2019 Jul 12.

Department of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska St. 64, Kyiv 01601, Ukraine.

In the title polymeric complex, {[Fe(CN)(CHN)(HO)][Au(CN)]} , the Fe ion, which is located on a twofold rotation axis, has a slightly distorted FeNO octa-hedral geometry. It is coordinated by two phenyl-pyrazine mol-ecules, two water mol-ecules and two di-cyano-aurate anions, the Au atom also being located on a second twofold rotation axis. In the crystal, the coordinated di-cyano-aurate anions bridge the Fe ions to form polymeric chains propagating along the -axis direction. In the crystal, the chains are linked by O-H⋯N hydrogen bonds and aurophillic inter-actions [Au⋯Au = 3.5661 (3) Å], forming layers parallel to the plane. The layers are linked by offset π-π stacking inter-actions [inter-centroid distance = 3.643 (3) Å], forming a supra-molecular metal-organic framework.
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http://dx.doi.org/10.1107/S2056989019009678DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690477PMC
August 2019

Nickel(II) Complexes with Redox Noninnocent Octaazamacrocycles as Catalysts in Oxidation Reactions.

Inorg Chem 2019 Aug 2;58(16):11133-11145. Epub 2019 Aug 2.

Institute of Inorganic Chemistry , University of Vienna , Währinger Strasse 42 , A-1090 Vienna , Austria.

Nickel(II) complexes with 15-membered (-) and 14-membered () octaazamacrocyclic ligands derived from 1,2- and 1,3-diketones and -methylisothiocarbohydrazide were prepared by template synthesis. The compounds were characterized by elemental analysis, electrospray ionization mass spectrometry, IR, UV-vis, H NMR spectroscopies, and X-ray diffraction. The complexes contain a low-spin nickel(II) ion in a square-planar coordination environment. The electrochemical behavior of - was investigated in detail, and the electronic structure of 1e-oxidized and 1e-reduced species was studied by electron paramagnetic resonance, UV-vis-near-IR spectroelectrochemistry, and density functional theory calculations indicating redox noninnocent behavior of the ligands. Compounds - were tested in the microwave-assisted solvent-free oxidation of cyclohexane by -butyl hydroperoxide to produce the industrially significant mixture of cyclohexanol and cyclohexanone (i.e., A/K oil). The results showed that the catalytic activity was affected by several factors, namely, reaction time and temperature or amount and type of catalyst. The best values for A/K oil yield (23%, turnover number of 1.1 × 10) were obtained with compound after 2 h of microwave irradiation at 100 °C.
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http://dx.doi.org/10.1021/acs.inorgchem.9b01700DOI Listing
August 2019

The Cytotoxic Properties of Some Tricyclic 1,3-Dithiolium Flavonoids.

Molecules 2019 Jul 4;24(13). Epub 2019 Jul 4.

Alexandru Ioan Cuza University of Iasi, Department of Chemistry, 11 Carol I Blvd., 700506 Iasi, Romania.

Background: Due to the emergence of multidrug resistant microorganisms, new classes of antibiotics are needed. In this paper, we present the cytotoxic effects of five tricyclic flavonoids, one of which was previously identified as a potent antimicrobial agent.

Methods: All five derivatives were tested against human HOS and MCF7 cancer cell lines using a wound scratch assay. The cytotoxic properties of previously reported flavonoid were also evaluated using the standard MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2-tetrazolium, inner salt) and live/dead assays, using NHDF, HOS and MCF7 cell lines.

Results: All five derivatives were found to inhibit to some degree the proliferation of cancer cells. was also found to be less toxic towards regular versus cancerous human cells. Moreover, the minimum bactericidal concentration of against was found to be non-toxic for any of the tested human cell lines.

Conclusions: Derivative has the potential of being used as a therapeutic agent against certain microorganisms. Further structure optimization is required for use against tumors.
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http://dx.doi.org/10.3390/molecules24132459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651846PMC
July 2019

Heterometallic 3d-4d coordination polymers assembled from trans-[Ru(L)(CN)] tectons and 3d cations.

Dalton Trans 2019 Oct;48(41):15455-15464

"Ilie Murgulescu" Institute of Physical Chemistry, Romanian Academy, Spl. Independentei no. 202, 060021-Bucharest, Romania.

Five new cyanido-bridged heterometallic coordination polymers have been obtained by reacting PPh4[RuIII(salpn)(CN)2]·H2O (1) and AsPh4[RuIII(valen)(CN)2]·8.5H2O (2) (H2salpn and H2valen being Schiff-base proligands resulting from the condensation reaction of salicylaldehyde with 1,3-propanediamine and, respectively, o-vanillin with 1,2-ethanediamine) with divalent transition metal perchlorate salts: ∞1[{RuIII(salpn)(CN)2}3{MII(DMF)3}2](ClO4)·4DMF (MII = Mn, 3; Co, 4) and ∞2[{RuIII(valen)(CN)2}4{MII(DMF)3}2{MII(DMF)4}](ClO4)2·4DMF (MII = Mn, 5; Co, 6; Ni, 7), respectively. The dicyanido species, trans-[Ru(salpn)(CN)2]- and trans-[Ru(valen)(CN)2]-, act as metalloligands with the 3d metal ions. Compounds 3 and 4 are isostructural one-dimensional (1D) coordination polymers with a ladder topology. Each MII ion is hexacoordinated by three cyanido groups arising from three {Ru(salpn)(CN)2} units and by the oxygen atoms from three DMF molecules, which are coordinated at meridional positions. Compounds 5-7 are also isostructural, their structures consisting of 2D networks with a herringbone topology. The magnetic susceptibility measurements of these 1D and 2D systems reveal the presence of dominating RuIII-MII antiferromagnetic (AF) interactions in compounds 3, 4, 5 and 6, while ferromagnetic RuIII-NiII interactions are observed in 7. All these compounds stay in their paramagnetic state down to 1.8 K except compound 4 which possesses a 3D ordered AF ground state.
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http://dx.doi.org/10.1039/c9dt01593kDOI Listing
October 2019

In situ generation of PhPO in cyanido-bridged heterometallic {FeLn} molecular squares (Ln = Eu, Sm).

Dalton Trans 2019 Jun 8;48(22):7532-7536. Epub 2019 May 8.

Department of Inorganic Chemistry, Physical Chemistry and Electrochemistry, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1-7 Gh. Polizu Street, 011061 Bucharest, Romania.

Two new examples of cyanido-bridged {FeLn} molecular squares, with pyim and PPhO as capping ligands at the Ln sites, exhibit weak antiferromagnetic interactions [Ln = Eu (1), Sm (2), pyim = 2-(1H-imidazol-2-yl)pyridine, PPhPO = triphenylphosphine oxide].
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http://dx.doi.org/10.1039/c9dt01445dDOI Listing
June 2019

Exploring isoxazoles and pyrrolidinones decorated with the 4,6-dimethoxy-1,3,5-triazine unit as human farnesyltransferase inhibitors.

Arch Pharm (Weinheim) 2019 May 4;352(5):e1800227. Epub 2019 Apr 4.

Faculty of Chemistry, Al. I. Cuza' University of Iasi, Iasi, Romania.

Unprecedented triazinyl-isoxazoles were afforded via an effective cycloaddition reaction between nitrile oxides and the scarcely described 2-ethynyl-4,6-dimethoxy-1,3,5-triazine as dipolarophile. The biological evaluation of the newly synthesized compounds showed that the inhibition of human farnesyltransferase by zinc complexation could be improved with triazine-isoxazole moieties. The replacement of the isoxazole unit by a pyrrolidin-2-one was detrimental to the inhibitory activity while the pyrrolidin-2-thione derivatives conserved the biological potential. The potential of selected compounds to disrupt protein farnesylation in Chinese hamster ovary (CHO) cells transfected with pEGFP-CAAX was also evaluated.
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http://dx.doi.org/10.1002/ardp.201800227DOI Listing
May 2019

Room temperature hysteretic spin crossover in a new cyanoheterometallic framework.

Chem Commun (Camb) 2019 Mar;55(23):3359-3362

Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine.

A new iron(ii)-based spin-crossover compound with thermal hysteresis operating under ambient conditions is reported. This complex exhibits a high reproducibility of the spin transition in many successive thermal cycles, stability of both spin states at room temperature and an attractive operational temperature range.
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http://dx.doi.org/10.1039/c8cc10260kDOI Listing
March 2019

X-ray Structure Elucidation of a Pt-Metalloporphyrin and Its Application for Obtaining Sensitive AuNPs-Plasmonic Hybrids Capable of Detecting Triiodide Anions.

Int J Mol Sci 2019 Feb 7;20(3). Epub 2019 Feb 7.

3Nano-SAE Research Center, Faculty of Physics, University of Bucharest, Atomistilor Street, No 405, 077125 Măgurele, Romania.

The development of UV⁻vis spectrophotometric methods based on metalloporphyrins for fast, highly sensitive and selective anion detection, which avoids several of the practical challenges associated with other detection methods, is of tremendous importance in analytical chemistry. In this study, we focused on achieving a selective optical sensor for triiodide ion detection in traces based on a novel hybrid material comprised of Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) and gold nanoparticles (AuNPs). This sensor has high relevance in medical physiological tests. The structure of PtTMeOPP was investigated by single crystal X-ray diffraction in order to understand the metal surroundings and the molecule conformation and to assess if it qualifies as a potential sensitive material. It was proven that the Pt-porphyrin generated 1D H-bond supramolecular chains due to the weak C-H···O intermolecular hydrogen bonding. The presence of ordered voids in the crystal encouraged us to use PtTMeOPP as the sensing material for triiodide ion and to enhance its potential in a novel AuNPs/PtTMeOPP hybrid by the synergistic effects provided by the plasmonic gold nanoparticles. The spectrophotometric sensor is characterized by a detection limit of 1.5 × 10 M triiodide ion concentration and a remarkable confidence coefficient of 99.98%.
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http://dx.doi.org/10.3390/ijms20030710DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6387073PMC
February 2019

Dinuclear manganese(iii) complexes with bioinspired coordination and variable linkers showing weak exchange effects: a synthetic, structural, spectroscopic and computation study.

Dalton Trans 2019 May;48(18):5909-5922

Inorganic Polymers Department, "Petru Poni" Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41 A, Iasi 700487, Romania.

Three dimanganese(iii) complexes have been synthesised and fully characterised by standard spectroscopic methods and spectroelectrochemistry. Each MnIII ion is chelated by a salen type ligand (H2L), but there is variation in the bridging group: LMn(OOCCH[double bond, length as m-dash]CHCOO)MnL, LMn(OOCC6H4COO)MnL, and LMn(OOCC6H4C6H4COO)MnL. X-ray diffraction revealed an axial compression of each six-coordinate high-spin d4 MnIII ion, which is a Jahn-Teller-active ion. Temperature dependent magnetic susceptibility and variable temperature-variable field (VTVH) magnetisation measurements, as well as high-frequency and -field EPR (HFEPR) spectroscopy were used to accurately describe the magnetic properties of the complexes, not only the single-ion spin Hamiltonian parameters: g-values and zero-field splitting (ZFS) parameters D and E, but also the exchange interaction constant J between the two ions, which has been seldom determined for a di-MnIII complex, particularly when there is more than a single bridging atom. Quantum chemical calculations reproduced well the electronic and geometric structure of these unusual complexes, and, in particular, their electronic absorption spectra along with the spin Hamiltonian and exchange parameters.
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http://dx.doi.org/10.1039/c8dt04596hDOI Listing
May 2019

Aggregation of [Ln] clusters by the dianion of 3-formylsalicylic acid. Synthesis, crystal structures, magnetic and luminescence properties.

Dalton Trans 2019 Jan;48(5):1700-1708

Inorganic Chemistry Laboratory, Faculty of Chemistry, University of Bucharest, Str. Dumbrava Rosie nr. 23, 020464-Bucharest, Romania.

Three isostrucutral dodecanuclear clusters with the general formula [Ln12(fsa)12(μf3-OH)12(DMF)12]·nDMF (fsa2- is the dianion of 3-formylsalicylic acid; Ln = Eu 1, Gd 2, Dy 3) have been obtained from the reaction of fromylsalicyclic acid (H2fsa), tetrabutylammonium hydroxide and Ln(NO3)3·6H2O in methanol/DMF. Their structure consists of four vertex-sharing heterocubanes. Each heterocubane unit is assembled from four LnIII ions, three μ3-OH groups and one μ3-oxygen atom arising from the fsa2- carboxylato group. The photophysical properties of the europium derivative investigated at both 300 and 80 K sustain a relative intense emission obtained under low power LED excitation at 420 nm. The dysprosium derivative shows a SMM behavior with an effective energy barrier Ueff of 22.9 cm-1, while the thermodynamical properties of Gd12 confirm a large magnetocaloric effect: S(7 T) - S(0 T) = 20R = 166 J mol-1 K), typical for isotropic GdIII derivatives, with ΔS = S(7 T) - S(0 T) = 1.7R for each GdIII ion.
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http://dx.doi.org/10.1039/c8dt04602fDOI Listing
January 2019

Schiff bases containing a furoxan moiety as potential nitric oxide donors in plant tissues.

PLoS One 2018 10;13(7):e0198121. Epub 2018 Jul 10.

"PetruPoni" Institute of Macromolecular Chemistry, Romanian Academy, Aleea Grigore Ghica Voda, Iasi, Romania.

Stable Schiff bases containing a furoxan moiety are synthesized as single regioisomers by the reaction of 3-methyl-2-oxy-furazan-4-carbaldehydewith various amino compounds at room temperature. The structures of synthesized compounds were fully characterized by multinuclear NMR spectroscopy and X-ray crystallography. The effect of synthesized Schiff bases containing a furoxan moiety on biological generation of reactive oxygen species and nitric oxide in plant tissues was investigated for the first time by fluorescence microscopy and the released NO identified as nitrite with Griess reagent. There is a good correlation between the biological generation of NO determined by fluorescence microscopy and with Griess reagent. Some of the synthesized compounds exhibited both nitric oxide and reactive oxygen species generation abilities and represent potential NO donors in plant tissues.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0198121PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6038987PMC
December 2018