Conversion of carbon dioxide (CO₂) captured from flue gases into synthetic natural gas (SNG) aims to create a closed carbon cycle, where excess H₂ produced from renewables is utilized to transform CO₂ released from existing conventional power plants into a reliable and high energy density carrier, that is CH₄. In the last five years, extensive research effort has been dedicated to the synthesis and optimization of composite materials for the realization of this process. These materials, also known as dual-function materials or DFMs, typically consist of an alkaline metal oxide or carbonate phase, along with a Ru or Ni metallic phase supported on a high surface area carrier. The DFMs incorporate both sorptive and catalytic capabilities, capturing the CO₂ in the initial sorption step and then converting it into CH₄ upon H₂ inflow. The dispersion of the sorptive and catalytically active phases, the CO₂ affinity of the alkaline phase, the reducibility of the supported metals and the selectivity towards CH₄ production are some of the parameters influencing their performance. Hereby, we aim to present the most recent works dedicated to the development and optimization of such dual-function materials to be used in the combined capture and the reaction of methanation of CO₂.

Ni/Al₂O₃ and Ni/CaO-MgO-Al₂O₃ catalysts were investigated for the biogas dry reforming reaction using CH₄/CO₂ mixtures with minimal dilution. Stability tests were conducted between 600 and 800 ^oC and TGA/DTG, Raman, STEM-HAADF, HR-TEM, XPS techniques were used to characterize the spent samples. Graphitized carbon allotrope structures, carbon nanotubes (CNTs) and amorphous carbon were formed on all samples. Metallic Ni⁰ was recorded for all (XPS), whereas a strong peak corresponding to Ni₂O₃/NiAl₂O₄ was observed for the Ni/Al₂O₃ sample (650–750°C). Stability tests confirmed that the Ni/CaO-MgO-Al₂O₃ catalyst deactivates at a more gradual rate and is more active and selective in comparison to the Ni/Al₂O₃ for all temperatures. The Ni/CaO-MgO-Al₂O₃ exhibits good durability in terms of conversion and selectivity, whereas the Ni/Al₂O₃ gradually loses its activity in CH₄ and CO₂ conversion, with a concomitant decrease of the H₂ and CO yield. It can be concluded that doping Al₂O₃ with CaO-MgO enhances catalytic performance by: (a) maintaining the Ni⁰ phase during the reaction, due to higher dispersion and stronger active phase-support interactions, (b) leading to a less graphitic and more defective type of deposited carbon, and (c) facilitating the deposited carbon gasification due to the enhanced CO₂ adsorption on its increased surface basic sites.

Commercial ZnO, was subjected to high-energy milling to introduce structural modifications, which can result in a different metal-support interaction. The milling time (0 to 960 min) and vial material and mill balls (WC and ZnO2), were modified. The supports were characterized by XRD, Scherrer, SBET, Raman Spectroscopy. With the increase in grinding time, an increase in the accrued kinetic energy (Ecum) was observed. For the same Ecum, with ZrO2, twice the area was obtained in just 6 min. Cu was deposited on both, the ground support (ZnO-z) and unmilled support (ZnO-0) in three compositions; x = 0.2, 0.5, and 1 (% wt). AAS measurements showed Cu compositions similar to the theoretical ones. XRD studies, Rietveld modeling and Raman Spectroscopy confirmed that Cu cations could be localized, either by substituting the Zn2+ ions or interstitially in the network, depending on the metal content. The TPR profiles showed two types of copper species, which interact differently with the support. Likewise, the analysis of the XPS results showed that, with the increase in Cu content, for Cux/ZnO-0 there is a decrease in the metal-support interaction. However, for Cux/ZnO-z the interaction increases, which can be associated with the introduction of structural defects accompanied by superficial energy changes. For both systems, different catalytic behaviors are expected in the hydrogenolysis reaction of glycerol in liquid phase, regarding selectivity and stability, as a result of the metal-support interaction achieved

Carbasugars are a wide group of carbohydrate mimetics in which the ring oxygen had been replaced by a methylene group.¹ The high importance of these compounds is related to their interesting biological and pharmacological properties which are the matter of current studies.

In our work, concise synthesis of carbasugars from naturally occurring D-pentoses is presented. The one-pot seleno-Michael reaction connected with intramolecular aldol reaction is a key step of the carbasugar core asymmetric synthesis. Further transformation of obtained carbasugar moiety led to different bioactive compounds.^{2, 3}

Tandem seleno-Michael reaction conjugated with oxidation/elimination step of in situ generated nucleophile has been described a few years ago in the intermolecular variant.⁴ In our work, we present the first example of this reaction in an intramolecular way which leads to a previously inaccessible cyclic product of Morita-Baylis-Hillman reaction. Conducted experiments allowed to receive cyclic products with high yields and good diastereoisomeric excesses.⁵

Further research on the developed method allows applying trimethylsilyl ethers as temporary protecting groups. This protocol drastically decreased synthesis time and resulted in total yields up to 40% from naturally occurring pentoses.

This work was financed by the Polish National Science Center (Grant No. 2015/17/D/ST5/01334 & 2018/31/N/ST5/03503)

[1] O. Arjona, A. M. Gómez, J. C. López, J. Plumet, Chem. Rev., 2007, 107, 1919.

[2] N. BiduÅ›; P. Banachowicz; S. Buda, Tetrahedron, 2020, doi.org/10.1016/j.tet.2020.131397.

[3] P. Banachowicz; S. Buda, RSC Adv., 2019, 9, 12928.

[4] B. A. Sousa, A. A. Dos Santos, Eur. J. Org. Chem., 2012, 18, 3431.

[5] P. Banachowicz; J. Mlynarski; S. Buda, J. Org. Chem., 2018, 83, 11269.

Since the beginning of the large-scale production of plastics in the 1950s, these materials have found a wide variety of applications and became essential in today’s society. Abandoned plastic waste poses an enormous environmental problem, contaminating the soil and oceans, due to the release of microplastics which are ingested by animals and end up in humans through food webs. Recent studies have highlighted the failure of traditional recycling processes thus new greener concepts and approaches have emerged, incorporating microorganisms and their enzymes for depolymerization of used plastics.

Studies dealing with the enzymatic degradation of synthetic polyesters have been performed for over 15 years. However, since 2016 the discussion about PET-degrading enzymes has bloomed. Turning point was the work of Yoshida et al, who discovered a PET-assimilating bacterium, namely Ideonella sakaiensis. The enzyme responsible for the degradation of the polymer was identified and named IsPETase. Till then, enzymes belonging to the family of cutinases had been studied for polyester degradation.

The present work aimed to the discovery of a novel polyester-degrading enzyme (polyesterase), using bioinformatics tools. The few known PET-degrading enzymes were used as templates for the identification of homologous sequences. The search led to a protein sequence originating from an Antarctic bacterium of the genus Moraxella sharing the highest similarity with IsPETase (45.2%), followed by actinomycete cutinases (41.48-46.05%). The recombinant protein (MorEst) was functionally expressed, purified and biochemically characterized, while its ability to degrade various synthetic polyesters (polyethylene terephthalate, polycaprolactone, polylactic acid, polyurethane) as well as model compounds was evaluated.

One-dimensional (1D) nanostructures, such as nanotubes, nanopores, nanodots and nanocones, are characterised by better catalytic properties than bulk material due to their large active surface area and small geometrical size. There are several methods of synthesis these structures, including the the one- and two-step methods. In the one-step method, a crystal modifier are added to the solution in order to limit horizontal direction of structures growing during electrodeposition. This method allows to fabricate nanocones without using chromic acid, which is dangerous for the environment. In this work, cobalt nanoconical structures were obtained from an electrolyte containing CoCl₂, H₃BO₃ and NH₄Cl as the crystal modifier.Another way of production of 1D nanocones is electrodeposition of metal into porous anodic alumina oxide (AAO) templates. This method is called the two-step method. It allows to control the geometrical features of nanostructures due to the features of used template. In this case, AAO template was obtained using two-step anodization. Then, electrodeposition of cobalt was performed from an electrolyte containing CoSO₄, H₃BO₃ and SDS. To obtain free standing nanocones the template has to be removed by immersion into dilute NaOH solution.

For determination of catalytic activity of synthesized material hydrogen evolution process have been chosen. The electrocatalytic properties of materials fabricated in one-step and two-step method were measured in 1M NaOH and compared with bulk materials. The microscopic pictures of material before and after hydrogen evolution will be searched and compare in order to detect any degradation of material surface morphology.

Polymers are involved in countless products ranging from high-tech materials used in areo-space industry, car parts, electronics to simple consumer goods such as clothing, sports gear, carpets, and various packing materials. As a result, humanity currently produces a previously unmatched amount of plastic waste. A lot of this waste is currently dumped in landfills or “mismanaged”.

In order to counter-act the pollution of the environment as well as to conserve natural resources several strategies have been proposed and developed for the recycling of polymeric materials. Depolymerization and mechanical recycling are being the most applied one. Both approaches have in common that it is very difficult for them to be cost competitive with the production of the virgin polymers.

A solution to this dilemma could be “chemical upcycling”. In this approach a polymer is converted to a new material or higher valuable commodity. In the case of polyesters, we could show that in the presence of a homogenous ruthenium catalyst and Lewis acids polyesters can be hydrogenated to polyether polyols. The type of Lewis acid and its ratio with respect to the ruthenium proofed to crucial. Based on mechanistic investigations it was shown that this reaction proceeds via a tandem hydrogenation/etherification process. The obtained polyether polyols are in the right molecular weight range for the use in adhesives.

The synthesis of organic compounds containing tellurium atom is shortly explored in the literature compared to their analogues selenium and sulfur. However, it is of great interest to obtain these compounds, among them a class of great importance are the symmetrical tellurides, which can be used as synthetic intermediates in a series of organic reactions, regarding their potential to the formation of new carbon-carbon bonds. Recent advances related to the preparation of diaryl tellurides have been described using boronic acids with different catalysts, such as copper, indium, iron, among others. The Ag-catalyzed reaction can be considered an efficient and attractive alternative, since AgNO₃ is not expensive and is easily handled. In this context, we have developed a efficient methodology for obtaining a series of symmetrical tellurides.

This work reports the synthesis of symmetrical tellurides starting from different arylboronic acids and tellurium powder through a simple methodology using silver catalysis. The developed method tolerates a series of arylboronic acids containing electron withdrawing or electron donating groups, obtaining a wide reaction scope using only 10 mol% of AgNO₃ as a catalyst, DMSO as solvent and three equivalents of Te⁰ for five hours. Using this methodology we are able to obtain a plethora of symmetrical tellurides in moderate to good yields.

Methylmercury is an important environmental contaminant and its toxicity in vertebrates is associated with its interaction with selenium (e.g., selenol groups of selenoproteins or HSe^- the pivotal metabolite for selenium incorporation into selenoproteins). In a previous study, we demonstrated that diphenyl diselenide (PhSe)₂ decreased the deposition of Hg in mice treated with MeHg⁺. We hypothesized that (PhSe)₂ could be reduced metabolically to its selenol intermediate phenylselenol (PhSeH), which reacted with MeHg⁺ to form PhSeHgMe. To further support our hypothesis, in this work, we investigate the electronic chemical reactivity descriptors at ZORA-OPBE-D3(BJ)/ level of theory using the Fukui functions and the Dual descriptors. The results indicate that (PhSe)₂ and diphenyl disulfide (PhS)₂ (f+ > f^- ) act as poor nucleophiles towards MeHg⁺ and thus cannot be the detoxificant agent. As further proof, the reaction between diphenyl diselenide and MeHgCl was followed via UV-vis spectrophotometry and the spectra of the relevant species were computed using time-dependent density functional theory (TD-DFT) (CPCM-ZORA-CAM-B3LYP/ZORA-def2-TZVP). The large aromatic system in (PhSe)₂ ensures the delocalization of electrons and directly influences the HOMO-LUMO gap (HLG) (3.34 eV) < HLG of PhSeH (3.99 eV). A similar trend was observed with HLG (2.65 eV) for (PhS)₂ and 4.13 eV for PhSH. This selenol intermediate is the active reactant, experimentally generated from the reduction of (PhSe)₂ by NaBH₄, which in presence of MeHgCl forms methylmercury phenylselenide complex (PhSeHgMe), i.e. a non-toxic metabolite of methylmercury formed after administration of (PhSe)₂ to mice.

Carbasugars are important carbohydrate analogs in which the ring oxygen is replaced with a methylene group. This change has no significant impact on structure (bonds length, torsion angles, conformation) but strongly affects biological activity (pharmacokinetics, molecule-enzyme interactions).¹ The therapeutic potential of some carbasugars has led to a growing interest in their development and identification.

In our work, we present our recent studies of the application of the tandem seleno-Michael/aldol process in carbasugar synthesis involving D-ribose as a readily available and cheap starting material. An intramolecular seleno-Michael/aldol reaction turned out to be a key step in the asymmetric synthesis of the carbasugar core. In situ generated lithium n-butylselenolate was used as the initiator in the reaction.^2,3 Regioselective Steglich esterification or methylation of the secondary hydroxyl and deprotection of benzyl ethers groups gave three known carbasugars (+)-COTC, (+)-Pericosine B and (+)-Pericosine C and a new 7-chloro-analogue of (+)-Gabosine C in satisfactory yields.³

This work was financed by the Polish National Science Center: Grant No. 2015/17/D/ST5/01334

[1] O. Arjona, A.M. Gomez, J.C. Lopez, J. Plumet, Chem. Rev. 107 (2007) 1919-2036

[2] P. Banachowicz; J. Mlynarski ; S.Buda , J. Org. Chem., 2018, 83, 11269-11277.

[3] N. BiduÅ›; P. Banachowicz; S. Buda, Tetrahedron, 2020, doi.org/10.1016/j.tet.2020.131397.