Publications by authors named "Szymon Sobczak"

12 Publications

  • Page 1 of 1

Stepwise Stress-Induced Transformations of Metal-Organic Polyhedral Cluster-Based Assemblies: Where Conformational and Supramolecular Features Meet.

Chemistry 2021 Jul 23. Epub 2021 Jul 23.

Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.

Understanding the factors governing the formation of supramolecular structures and phase transitions between various forms of molecular crystals is pivotal for developing dynamic, stimuli-responsive materials and polymorph-controlled syntheses. Here, we investigate the pressure-induced dynamic of both the intrinsic molecular structure and the supramolecular network of a predesigned polyhedral oxo-centered zinc cluster incorporating monoanionic N,N'-diphenylformamidinate and featuring N-bonded phenyl groups in close proximity to the primary coordination sphere. We demonstrate that the model oxo cluster is prone to undergoing pressure-induced conformational transformations of the secondary coordination sphere and simultaneous stepwise (initially every second polyhedral molecule undergoes the conformational transformations) and reversible transitions from an ambient phase α to high-pressure phases β and γ, as single-crystal-to-single-crystal events. The observed phase transitions illustrate the key role of an interplay between the low-energy conformation perturbations and cooperative intra- and intermolecular noncovalent interactions.
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http://dx.doi.org/10.1002/chem.202101732DOI Listing
July 2021

High-pressure Nucleation of Low-Density Polymorphs.

Chemistry 2021 Apr 15;27(24):6999. Epub 2021 Apr 15.

Department of Materials Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznań, Poland.

Invited for the cover of this issue is the group of Andrzej Katrusiak at Adam Mickiewicz University. The image depicts a wave and the sun, which represent the high energy required for the high-entropy nucleation reported in this work. Read the full text of the article at 10.1002/chem.202005121.
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http://dx.doi.org/10.1002/chem.202101159DOI Listing
April 2021

High-pressure Nucleation of Low-Density Polymorphs*.

Chemistry 2021 Apr 4;27(24):7069-7073. Epub 2021 Mar 4.

Department of Materials Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznań, Poland.

New polymorphs β and γ of bis-3-nitrophenyl disulphide, crystallized above 0.3 GPa, are less dense than the ambient-pressure polymorph α. This counterintuitive density relation results from the high-entropy nucleation and subsequent kinetic crystallization. The work performed by pressure compensates the high entropy and temperature product, substantiated in varied conformers and increased chemical potential. Pressure-increased viscosity promotes the kinetic polymorphs, in accordance with empirical Ostwald's rule of stages. It contrasts to mechanochemical techniques, favouring high-density polymorphs.
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http://dx.doi.org/10.1002/chem.202005121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252116PMC
April 2021

Photoinduced Skeletal Rearrangement of -Substituted Colchicine Derivatives.

J Org Chem 2021 Aug 22;86(16):11029-11039. Epub 2020 Dec 22.

Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.

Colchicine is an active pharmaceutical ingredient widely used for treating gout, pericarditis, and familial Mediterranean fever with high antimitotic activity. The photoisomerization of colchicine deactivates its anti-inflammatory and antimitotic properties. However, despite numerous reports on colchicine derivatives, their photostability has not been investigated in detail. This report reveals the effects of UV-induced rearrangement on the structure and reports the biological activity of new -substituted colchicine derivatives.
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http://dx.doi.org/10.1021/acs.joc.0c02507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8383305PMC
August 2021

Large negative linear compressibility of a porous molecular co-crystal.

Chem Commun (Camb) 2020 Apr 19;56(31):4324-4327. Epub 2020 Mar 19.

Department of Chemistry, Adam Mickiewicz University, Poznań, Poland.

Flexible and transformable molecules, particularly those responding to external stimuli, are needed for designing sensors and porous compounds capable of storing or separating gases and liquids. Under normal conditions the photochromic compound, 1,2-bis[2-methyl-5-(pyridyl)-3thienyl]cyclopentene (BTCP) forms a porous co-crystal with 1,4-diiodotetrafluorobenzene (dItFB). It traps acetone (Ac) molecules in the pores. Owing to a unique system of pores in the polar framework, the crystal is sensitive to the humidity in the air and to the chosen liquid environment. When compressed in non-penetrating media, the crystal displays a strong negative linear compressibility (NLC) along [100].
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http://dx.doi.org/10.1039/d0cc00461hDOI Listing
April 2020

Synthesis and Antiproliferative Screening Of Novel Analogs of Regioselectively Demethylated Colchicine and Thiocolchicine.

Molecules 2020 Mar 5;25(5). Epub 2020 Mar 5.

Department of Medical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznan, Poland.

Colchicine, a pseudoalkaloid isolated from , has been identified as a potent anticancer agent because of its strong antimitotic activity. It was shown that colchicine modifications by regioselective demethylation affected its biological properties. For demethylated colchicine analogs, 10-demethylcolchicine (colchiceine, ) and 1-demethylthiocolchicine (), a series of 12 colchicine derivatives including 5 novel esters (- and -) and 4 carbonates (- and -) were synthesized. The antiproliferative activity assay, together with evaluation of physicochemical properties, confirmed attractive biological profiles for all obtained compounds. The substitutions of H-donor and H-acceptor sites at C1 in thiocolchicine position provide an efficient control of the hydration affinity and solubility, as demonstrated for anhydrate , hemihydrate and monohydrate .
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http://dx.doi.org/10.3390/molecules25051180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7179419PMC
March 2020

Synthesis and Anticancer Activity of Tertiary Amides of Salinomycin and Their C20-oxo Analogues.

ChemMedChem 2020 01 27;15(2):236-246. Epub 2019 Nov 27.

Department of Bioorganic Chemistry Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614, Poznań, Poland.

The polyether ionophore salinomycin (SAL) has captured much interest because of its potent activity against cancer cells and cancer stem cells. Our previous studies have indicated that C1/C20 double-modification of SAL is a useful strategy to generate diverse agents with promising biological activity profiles. Thus, herein we describe the synthesis of a new class of SAL analogues that combine key modifications at the C1 and C20 positions. The activity of the obtained SAL derivatives was evaluated using primary acute lymphoblastic leukemia, human breast adenocarcinoma and normal mammary epithelial cells. One single- [N,N-dipropyl amide of salinomycin (5 a)] and two novel double-modified analogues [N,N-dipropyl amide of C20-oxosalinomycin (5 b) and piperazine amide of C20-oxosalinomycin (13 b)] were found to be more potent toward the MDA-MB-231 cell line than SAL or its C20-oxo analogue 2. When select analogues were tested against the NCI-60 human tumor cell line panel, 4 a [N,N-diethyl amide of salinomycin] showed particular activity toward the ovarian cancer cell line SK-OV-3. Additionally, both SAL and 2 were found to be potent ex vivo against human ER/PR , Her2 invasive mammary carcinoma, with 2 showing minimal toxicity toward normal epithelial cells. The present findings highlight the therapeutic potential of SAL derivatives for select targeting of different cancer types.
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http://dx.doi.org/10.1002/cmdc.201900593DOI Listing
January 2020

Environment-Controlled Postsynthetic Modifications of Iron Formate Frameworks.

Inorg Chem 2019 Sep 22;58(17):11773-11781. Epub 2019 Aug 22.

Faculty of Chemistry , Adam Mickiewicz University , Uniwersytetu Poznańskiego 8 , 61-614 Poznań , Poland.

New, hybrid iron-formate perovskites have been obtained in high-pressure reactions. In addition to the pressure range, the liquid environment of the sample also regulates the course of transformations. Formate α-DmaFeFeFor (Dma = (CH)NH, For = HCOO), when compressed in oil or in isopropanol at 1.40 GPa, transforms to a new phase γ, different than that obtained at low-temperature (phase β). In glycerol, phase α can be compressed to 1.40 GPa, but then it reacts to DmaFeFor, with all Fe(III) cations reduced, surrounded by amorphous iron formate devoid of Dma cations. Another mixed-valence framework DmaFeFeFor·CO can be produced from phase α incubated in methanol and ethanol at 1.15 GPa. These pressure-induced environment-sensitive modifications have been rationalized by the volume effects in transforming structures, their different chemical composition, voids, ligands, and cation oxidation states switching between Fe(II), Fe(III), their high- and low-spin states, as well as solubility, molecular size, and the chemical and physical properties of the pressure transmitting media. The topochemical redox paths controlled by pressure and the liquid environment offer new highly efficient, safe, and environment-friendly reactions leading to new advanced materials and their postsynthetic modifications.
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http://dx.doi.org/10.1021/acs.inorgchem.9b01817DOI Listing
September 2019

Gold nanorods as a high-pressure sensor of phase transitions and refractive-index gauge.

Nanoscale 2019 May;11(18):8718-8726

Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznań, Poland.

Gold nanorods (Au NRs), nanospheres and other nanoparticles display numerous superior physicochemical properties, such as resistance to oxidation and aggressive agents, strong enhancement of local electric field and a high absorption coefficient in the visible and near-infrared (NIR) range. The absorption peaks of surface plasmon resonance (SPR) in Au NRs are highly sensitive to their surrounding medium and to its refractive index (RI) changes. However, no applications of NRs for detecting phase transitions have been reported. Here, we show that Au NRs effectively detect phase transitions of compressed compounds, liquid and solid, by measuring their RI. Owing to the direct interaction of the NRs with their surrounding medium, its subtle RI changes can be observed by the use of high-pressure absorption vis-NIR spectroscopy. We have applied a Au NR-based sensor in a diamond anvil cell (DAC) for monitoring the phase transitions of compressed water, its freezing to ice VI and at the subsequent solid-solid phase transition to ice VII, and the monotonic compression and solid-solid phase transitions in urea and thiourea.
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http://dx.doi.org/10.1039/c9nr02792kDOI Listing
May 2019

Dynamic Resolution of Piezosensitivity in Single Crystals of π-Conjugated Molecules.

Chemistry 2019 Apr 10;25(24):6092-6097. Epub 2019 Apr 10.

Chemistry and Physics of Materials Unit, School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India.

Targeted synthesis of piezoresponsive small molecules and in-depth understanding of their mechanism is of utmost importance for the development of smart devices. This work reports the synthesis, structure and piezosensitivity of a bola-amphiphile 1,4-bis(pentyloxy)-2,5-bis(2-pyridineethynyl)-benzene (C5-PPB). Depending on the rate of compression, two different phases in C5-PPB can be generated. The ambient-pressure α-phase is stable up to 0.8 GPa, beyond which it undergoes an isostructural transformation to β-phase, accompanied by a clearly visible elongation of the crystal. This α-to-β phase transition requires the sample to be compressed slowly. When quickly compressed, phase α persists to about 1.5 GPa, beyond which its amorphization starts, accompanied by the appearance of irregular grooves on the largest faces. Mechanical pressure also affects the optical property of C5-PPB, which shows reversible mechanochromism with a green to cyan transformation in the emission, associated with a 15 nm shift in the maxima. The conductivity of C5-PPB as a direct outcome of its crystal packing has also been studied.
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http://dx.doi.org/10.1002/chem.201900054DOI Listing
April 2019

Solid-State Associative Reactions and the Coordination Compression Mechanism.

Inorg Chem 2018 Aug 6;57(15):8942-8950. Epub 2018 Jul 6.

Department of Materials Chemistry, Faculty of Chemistry , Adam Mickiewicz University , Umultowska 89b , 61-614 Poznan , Poland.

Coordination polymers and metal-organic frameworks can be modified by high pressure, according to its effects on the radii of central and ligand atoms. The pressure reduces the ligands' radii, and the coordination number is usually increased. Such transformations of the coordination quite generally conform to the inverse rule of pressure and temperature effects, although the temperature-induced transformations are much less frequently observed. The two-dimensional coordination polymer Cd(APP)NO·NO [APP = 1,4-bis(3-aminopropyl)piperazine] undergoes a pressure-induced isostructural phase transition triggered by a topochemical reaction, yielding Cd(APP)(NO). The transition retains the symmetry of both phases, and their structures have been determined by X-ray diffraction for the single crystals compressed in a diamond-anvil cell. The reaction increases the Cd coordination, from 6-fold in phase I to 7-fold in phase II, where the new Cd-O bond involves an additional nitrate anion in the Cd coordination sphere.
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http://dx.doi.org/10.1021/acs.inorgchem.8b00913DOI Listing
August 2018

Dynamic Covalent Chemistry under High-Pressure:A New Route to Disulfide Metathesis.

Chemistry 2018 Jun 30;24(35):8769-8773. Epub 2018 May 30.

Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614, Poznań, Poland.

This work describes, for the first time, the application of combined pressure and temperature stimuli in disulfide metathesis reactions. In the system studied, above a pressure of 0.2 GPa, equimolar amounts of symmetric disulfides bis 4-chlorophenyl disulfide [(4-ClPhS) ] and bis 2-nitrophenyl disulfide [(2-NO PhS) ] react to give the heterodimeric product 4-Cl-PhSSPh-2-NO . In contrast to experiments conducted in solution at atmospheric pressure or in mechanochemical experiments under ball-mill grinding conditions, there is no necessity to use a base or thiolate anion as a catalyst for the exchange reaction under investigated conditions. Single-crystal and powder X-ray diffraction revealed also that, despite the high-pressure conditions of this reaction, the heterodimeric-disulfide product unexpectedly crystallizes into the low-density polymorph A. This counterintuitive result contrasts with the high-pressure stability of the higher-density polymorph B, confirmed by its compression up to 2.8 GPa with no signs of a phase transition.
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http://dx.doi.org/10.1002/chem.201801740DOI Listing
June 2018
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