International Journal of Molecular Sciences

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8 pages, 6651 KiB

Open AccessCommunication

Tailored Water-Soluble Covalent Organic Cages for Encapsulation of Pyrene and Information Encryption

by Haixin Song, Yujing Guo, Guorui Zhang and Linlin Shi

Int. J. Mol. Sci. 2023, 24(24), 17541; https://doi.org/10.3390/ijms242417541 - 16 Dec 2023

Viewed by 709

Forming pyridine salts to construct covalent organic cages is an effective strategy for constructing covalent cage compounds. Covalent organic cages based on pyridine salt structures are prone to form water-soluble supramolecular compounds. Herein, we designed and synthesized a triangular prism-shaped hexagonal cage with [...] Read more.

Forming pyridine salts to construct covalent organic cages is an effective strategy for constructing covalent cage compounds. Covalent organic cages based on pyridine salt structures are prone to form water-soluble supramolecular compounds. Herein, we designed and synthesized a triangular prism-shaped hexagonal cage with a larger cavity and relatively flexible conformation. The supramolecular cage structure was also applied to the encapsulation of pyrene and information encryption. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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14 pages, 25000 KiB

Open AccessArticle

Reactive Molecular Dynamics Simulations of Polystyrene Pyrolysis

by Chao Li, Zhaoying Yang, Xinge Wu, Shuai Shao, Xiangying Meng and Gaowu Qin

Int. J. Mol. Sci. 2023, 24(22), 16403; https://doi.org/10.3390/ijms242216403 - 16 Nov 2023

Viewed by 754

Abstract

Polymers’ controlled pyrolysis is an economical and environmentally friendly solution to prepare activated carbon. However, due to the experimental difficulty in measuring the dependence between microstructure and pyrolysis parameters at high temperatures, the unknown pyrolysis mechanism hinders access to the target products with [...] Read more.

Polymers’ controlled pyrolysis is an economical and environmentally friendly solution to prepare activated carbon. However, due to the experimental difficulty in measuring the dependence between microstructure and pyrolysis parameters at high temperatures, the unknown pyrolysis mechanism hinders access to the target products with desirable morphologies and performances. In this study, we investigate the pyrolysis process of polystyrene (PS) under different heating rates and temperatures employing reactive molecular dynamics (ReaxFF-MD) simulations. A clear profile of the generation of pyrolysis products determined by the temperature and heating rate is constructed. It is found that the heating rate affects the type and amount of pyrolysis intermediates and their timing, and that low-rate heating helps yield more diverse pyrolysis intermediates. While the temperature affects the pyrolytic structure of the final equilibrium products, either too low or too high a target temperature is detrimental to generating large areas of the graphitized structure. The reduced time plots (RTPs) with simulation results predict a PS pyrolytic activation energy of 159.74 kJ/mol. The established theoretical evolution process matches experiments well, thus, contributing to preparing target activated carbons by referring to the regulatory mechanism of pyrolytic microstructure. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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14 pages, 3345 KiB

Open AccessArticle

Temperature Stable Ion Exchange Resins as Catalysts for the Manufacturing of Vitamin Precursors by Aldol Reaction

by Jonas Vosberg, Thomas Bouveyron, Simon Eisen-Winter, Jan Drönner, Gerhard Raabe, Pierre Vanhoorne, Sven Behnke and Matthias Eisenacher

Int. J. Mol. Sci. 2023, 24(18), 14367; https://doi.org/10.3390/ijms241814367 - 21 Sep 2023

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Abstract

This study explores the potential of robust, strongly basic type I ion exchange resins—specifically, Amberlyst^® A26 OH and Lewatit^® K 6465—as catalysts for the aldol condensation of citral and acetone, yielding pseudoionone. Emphasis is placed on their long-term stability and commendable [...] Read more.

This study explores the potential of robust, strongly basic type I ion exchange resins—specifically, Amberlyst^® A26 OH and Lewatit^® K 6465—as catalysts for the aldol condensation of citral and acetone, yielding pseudoionone. Emphasis is placed on their long-term stability and commendable performance in continuous operational settings. The aldol reaction, which traditionally is carried out using aqueous sodium hydroxide as the catalyst, holds the potential for enhanced sustainability and reduced waste production through the use of basic ion exchange resins in heterogeneous catalysis. Density Functional Theory (DFT) calculations are employed to investigate catalyst deactivation mechanisms. The result of these calculations indicates that the active sites of Amberlyst^® A26 OH are cleaved more easily than the active sites of Lewatit^® K 6465. However, the experimental data show a gradual decline in catalytic activity for both resins. Batch experiments reveal Amberlyst^® A26 OH’s active sites diminishing, while Lewatit^® K 6465 maintains relative consistency. This points to distinct deactivation processes for each catalyst. The constant count of basic sites in Lewatit^® K 6465 during the reaction suggests additional factors due to its unique polymer structure. This intriguing observation also highlights an exceptional temperature stability for Lewatit^® K 6465 compared to Amberlyst^® A26 OH, effectively surmounting one of the prominent challenges associated with the utilization of ion exchange resins in catalytic applications. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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21 pages, 4510 KiB

Open AccessArticle

Highly Porous Carbon Materials Derived from Silicon Oxycarbides and Effect of the Pyrolysis Temperature on Their Electrochemical Response

by Jose Merida, Maria T. Colomer, Fausto Rubio and M. Alejandra Mazo

Int. J. Mol. Sci. 2023, 24(18), 13868; https://doi.org/10.3390/ijms241813868 - 08 Sep 2023

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Abstract

The design of a material porous microstructure with interconnected micro-meso-macropores is a key issue for the successful development of carbon-derived materials for supercapacitor applications. Another important issue is the nature of these carbon materials. For those reasons, in this study, novel hierarchical micro-meso-macroporous [...] Read more.

The design of a material porous microstructure with interconnected micro-meso-macropores is a key issue for the successful development of carbon-derived materials for supercapacitor applications. Another important issue is the nature of these carbon materials. For those reasons, in this study, novel hierarchical micro-meso-macroporous silicon oxycarbide-derived carbon (SiOC-DC) was obtained via chlorine etching of carbon-enriched SiOC prepared via pyrolysis (1100–1400 °C) of sol-gel triethoxysilane/dimethyldiphenysiloxane hybrids. In addition, and for the first time, non-conventional Raman parameters combined with the analysis of their microstructural characteristics were considered to establish their relationships with their electrochemical response. The sample pyrolyzed at 1100 °C showed planar and less-defective carbon domains together with the largest specific surface area (SSA) and the highest volume of micro-meso-macropores, which upgraded their electrochemical response. This sample has the highest specific capacitance (C_s = 101 Fg⁻¹ (0.2 Ag⁻¹)), energy (E_d = 12–7 Wh⁻¹ kg⁻¹), and power densities (P_d = 0.32–35 kw kg⁻¹), showing a good capacitance retention ratio up to 98% after 10,000 charge–discharge cycles at 0.5 Ag⁻¹. At a pyrolysis temperature ≥ 1200 °C, the carbon domains were highly ordered and tortuous with a high degree of interconnection. However, SSA and pore volumes (micro-meso-macropores) were significantly reduced and downgraded the C_s, E_d, and P_d values. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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13 pages, 2104 KiB

Open AccessArticle

Phosphate Additives for Aging Inhibition of Impregnated Activated Carbon against Hazardous Gases

by Ido Nir, Vladislav Shepelev, Alexander Pevzner, Daniele Marciano, Lilach Rosh, Tal Amitay-Rosen and Hadar Rotter

Int. J. Mol. Sci. 2023, 24(16), 13000; https://doi.org/10.3390/ijms241613000 - 20 Aug 2023

Cited by 1 | Viewed by 913

Abstract

Impregnated activated carbons (IACs) used in air filtration gradually lose their efficacy for the chemisorption of noxious gases when exposed to humidity due to impregnated metal deactivation. In order to stabilize IACs against aging, and to prolong the filters’ shelf life, inorganic phosphate [...] Read more.

Impregnated activated carbons (IACs) used in air filtration gradually lose their efficacy for the chemisorption of noxious gases when exposed to humidity due to impregnated metal deactivation. In order to stabilize IACs against aging, and to prolong the filters’ shelf life, inorganic phosphate compounds (phosphoric acid and its three salts, NaHPO₄, Na₂HPO₄, and Na₃PO₄) were used as anti-aging additives for two different chromium-free IACs impregnated with copper, zinc, molybdenum, and triethylenediamine (TEDA). Phosphoric acid, monosodium, and disodium phosphate were found to be very efficient in inhibiting the aging of IACs over long periods against cyanogen chloride (the test agent) chemisorption, with the latter being the most efficient. However, the efficiency of phosphate as an anti-aging additive was not well correlated with its ability to inhibit the migration of metal impregnants, especially copper, from the interior to the external surface of carbon granules. Unlike organic additives, the inorganic phosphate additives did not decrease the surface area of the IAC or its physical adsorption capacity for toluene. Using a phosphate additive in IAC used in collective protection and personal filters can improve the safety of the user and the environment and dramatically reduce the need to replace these filters after exposure to humid environments. This has safety, economic, logistical, and environmental advantages. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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15 pages, 4747 KiB

Open AccessArticle

Strategic Design and Synthesis of Ferrocene Linked Porous Organic Frameworks toward Tunable CO₂ Capture and Energy Storage

by Aya Osama Mousa, Cheng-Hsin Chuang, Shiao-Wei Kuo and Mohamed Gamal Mohamed

Int. J. Mol. Sci. 2023, 24(15), 12371; https://doi.org/10.3390/ijms241512371 - 02 Aug 2023

Cited by 11 | Viewed by 1395

Abstract

This work focuses on porous organic polymers (POPs), which have gained significant global attention for their potential in energy storage and carbon dioxide (CO₂) capture. The study introduces the development of two novel porous organic polymers, namely FEC-Mel and FEC-PBDT POPs, [...] Read more.

This work focuses on porous organic polymers (POPs), which have gained significant global attention for their potential in energy storage and carbon dioxide (CO₂) capture. The study introduces the development of two novel porous organic polymers, namely FEC-Mel and FEC-PBDT POPs, constructed using a simple method based on the ferrocene unit (FEC) combined with melamine (Mel) and 6,6′-(1,4-phenylene)bis(1,3,5-triazine-2,4-diamine) (PBDT). The synthesis involved the condensation reaction between ferrocenecarboxaldehyde monomer (FEC-CHO) and the respective aryl amines. Several analytical methods were employed to investigate the physical characteristics, chemical structure, morphology, and potential applications of these porous materials. Through thermogravimetric analysis (TGA), it was observed that both FEC-Mel and FEC-PBDT POPs exhibited exceptional thermal stability. FEC-Mel POP displayed a higher surface area and porosity, measuring 556 m² g⁻¹ and 1.26 cm³ g⁻¹, respectively. These FEC-POPs possess large surface areas, making them promising materials for applications such as supercapacitor (SC) electrodes and gas adsorption. With 82 F g⁻¹ of specific capacitance at 0.5 A g⁻¹, the FEC-PBDT POP electrode has exceptional electrochemical characteristics. In addition, the FEC-Mel POP showed remarkable CO₂ absorption capabilities, with 1.34 and 1.75 mmol g⁻¹ (determined at 298 and 273 K; respectively). The potential of the FEC-POPs created in this work for CO₂ capacity and electrical testing are highlighted by these results. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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17 pages, 5681 KiB

Open AccessArticle

Sustainable Solution for Plastic Pollution: Upcycling Waste Polypropylene Masks for Effective Oil-Spill Management

by Junaid Saleem, Zubair Khalid Baig Moghal, Rana Abdul Shakoor and Gordon McKay

Int. J. Mol. Sci. 2023, 24(15), 12368; https://doi.org/10.3390/ijms241512368 - 02 Aug 2023

Cited by 6 | Viewed by 2222

Abstract

The use of Polypropylene PP in disposable items such as face masks, gloves, and personal protective equipment has increased exponentially during and after the COVID-19 pandemic, contributing significantly to microplastics and nanoplastics in the environment. Upcycling of waste PP provides a useful alternative [...] Read more.

The use of Polypropylene PP in disposable items such as face masks, gloves, and personal protective equipment has increased exponentially during and after the COVID-19 pandemic, contributing significantly to microplastics and nanoplastics in the environment. Upcycling of waste PP provides a useful alternative to traditional thermal and mechanical recycling techniques. It transforms waste PP into useful products, minimizing its impact on the environment. Herein, we synthesized an oil-sorbent pouch using waste PP, which comprises superposed microporous and fibrous thin films of PP using spin coating. The pouch exhibited super-fast uptake kinetics and reached its saturation in fewer than five minutes with a high oil uptake value of 85 g/g. Moreover, it displayed high reusability and was found to be effective in absorbing oil up to seven times when mechanically squeezed between each cycle, demonstrating robust oil-sorption capabilities. This approach offers a potential solution for managing plastic waste while promoting a circular economy. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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17 pages, 6304 KiB

Open AccessArticle

Antibacterial Films of Silver Nanoparticles Embedded into Carboxymethylcellulose/Chitosan Multilayers on Nanoporous Silicon: A Layer-by-Layer Assembly Approach Comparing Dip and Spin Coating

by Nelson Naveas, Ruth Pulido, Vicente Torres-Costa, Fernando Agulló-Rueda, Mauricio Santibáñez, Francisco Malano, Gonzalo Recio-Sánchez, Karla A. Garrido-Miranda, Miguel Manso-Silván and Jacobo Hernández-Montelongo

Int. J. Mol. Sci. 2023, 24(13), 10595; https://doi.org/10.3390/ijms241310595 - 24 Jun 2023

Cited by 2 | Viewed by 1419

Abstract

The design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes [...] Read more.

The design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes the formation of antibacterial films with AgNPs embedded in carboxymethylcellulose/chitosan multilayers by the layer-by-layer (LbL) method. The films were deposited onto nanoporous silicon (nPSi), an ideal platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. We focused on two alternative multilayer deposition processes: cyclic dip coating (CDC) and cyclic spin coating (CSC). The physicochemical properties of the films were the subject of microscopic, microstructural, and surface–interface analyses. The antibacterial activity of each film was investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria strains as model microorganisms. According to the findings, the CDC technique produced multilayer films with higher antibacterial activity for both bacteria compared to the CSC method. Bacteria adhesion inhibition was observed from only three cycles. The developed AgNPs–multilayer composite film offers advantageous antibacterial properties for biomedical applications. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Macroporous, Mesoporous, and Microporous Materials)

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