Molecules

29 pages, 1719 KB

Open AccessArticle

Fatty Acid and Amino Acid Derivatives in Organocatalyzed Michael Additions

by Aljaž Flis, Helena Brodnik, Nejc Petek, Franc Požgan, Jurij Svete, Bogdan Štefane, Luka Ciber and Uroš Grošelj

Molecules 2026, 31(2), 204; https://doi.org/10.3390/molecules31020204 - 6 Jan 2026

Abstract

Amino acid derivatives, such as β-keto esters and pyrrolones, were used as nucleophiles in organocatalyzed Michael additions to nitroalkene acceptors, while fatty acid derivatives acted as both nucleophiles (β-keto esters) and electrophiles (nitroalkene acceptors). Bifunctional noncovalent organocatalysts were employed as asymmetric organocatalysts. Twenty [...] Read more.

Amino acid derivatives, such as β-keto esters and pyrrolones, were used as nucleophiles in organocatalyzed Michael additions to nitroalkene acceptors, while fatty acid derivatives acted as both nucleophiles (β-keto esters) and electrophiles (nitroalkene acceptors). Bifunctional noncovalent organocatalysts were employed as asymmetric organocatalysts. Twenty compounds—including fatty acid and amino acid derivatives, as well as fatty acid–amino acid conjugates—were prepared with enantioselectivities of up to 98% ee. All novel products were fully characterized. This research demonstrates the ease of assembling readily available fatty acid and amino acid building blocks under ambient conditions. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry—Third Edition)

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51 pages, 12092 KB

Open AccessReview

Smart Delayed Fluorescent AIEgens for Organic Light-Emitting Diodes: Mechanism and Adjustable Performance

by Changhao Yan and Juechen Ni

Molecules 2026, 31(2), 203; https://doi.org/10.3390/molecules31020203 - 6 Jan 2026

Abstract

Organic light-emitting diodes (OLEDs) have attracted remarkable interest in display and lighting. To effectively address triplet exciton harvesting and enhance external quantum efficiency (EQE), delayed fluorescence AIEgens have gained significant prominence. The primary luminescence mechanism involves the efficient harvesting of triplet excitons via [...] Read more.

Organic light-emitting diodes (OLEDs) have attracted remarkable interest in display and lighting. To effectively address triplet exciton harvesting and enhance external quantum efficiency (EQE), delayed fluorescence AIEgens have gained significant prominence. The primary luminescence mechanism involves the efficient harvesting of triplet excitons via reverse intersystem crossing (RISC) channels, categorized into three types: thermally activated delayed fluorescence (TADF), hybridized local and charge transfer (HLCT), and triplet–triplet annihilation (TTA). In this review, we summarize the recent development of doped and non-doped delayed fluorescent AIEgens-based OLEDs. This review mainly discusses the molecular design strategies and photophysical properties of delayed fluorescent AIEgens and the electroluminescent properties of OLEDs as emitting layers. Finally, the challenges and prospects of delayed fluorescent AIEgens for the fabrication of OLEDs are also briefly discussed. Full article

(This article belongs to the Special Issue Design and Synthesis of Organic Materials for OLED Applications)

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51 pages, 4344 KB

Open AccessReview

Mechanistic Pathways and Product Selectivity in Pyrolysis of PE, PP and PVC: A Foundation for Applied Chemistry in Europe

by Tim Tetičkovič, Dušan Klinar, Klavdija Rižnar and Darja Pečar

Molecules 2026, 31(2), 202; https://doi.org/10.3390/molecules31020202 - 6 Jan 2026

Abstract

Plastic streams dominated by polyethylene (PE) including PE HD/MD (High Density/Medium Density) and PE LD/LLD (Low Density/Linear Low Density), polypropylene (PP), and polyvinyl chloride (PVC) across Europe demand a design framework that links synthesis with end of life reactivity, supporting circular economic goals [...] Read more.

Plastic streams dominated by polyethylene (PE) including PE HD/MD (High Density/Medium Density) and PE LD/LLD (Low Density/Linear Low Density), polypropylene (PP), and polyvinyl chloride (PVC) across Europe demand a design framework that links synthesis with end of life reactivity, supporting circular economic goals and European Union waste management targets. This work integrates polymerization derived chain architecture and depolymerization mechanisms to guide selective valorization of commercial plastic wastes in the European context. Catalytic topologies such as Bronsted or Lewis acidity, framework aluminum siting, micro and mesoporosity, initiators, and strategies for process termination are evaluated under relevant variables including temperature, heating rate, vapor residence time, and pressure as encountered in industrial practice throughout Europe. The analysis demonstrates that polymer chain architecture constrains reaction pathways and attainable product profiles, while additives, catalyst residues, and contaminants in real waste streams can shift radical populations and observed selectivity under otherwise similar operating windows. For example, strong Bronsted acidity and shape selective micropores favor the formation of C₂ to C₄ olefins and Benzene, Toluene, and Xylene (BTX) aromatics, while weaker acidity and hierarchical porosity help preserve chain length, resulting in paraffinic oils and waxes. Increasing mesopore content shortens contact times and limits undesired secondary cracking. The use of suitable initiators lowers the energy threshold and broadens processing options, whereas diffusion management and surface passivation help reduce catalyst deactivation. In the case of PVC, continuous hydrogen chloride removal and the use of basic or redox co catalysts or ionic liquids reduce the dehydrochlorination temperature and improve fraction purity. Staged dechlorination followed by subsequent residue cracking is essential to obtain high quality output and prevent the release of harmful by products within European Union approved processes. Framing process design as a sequence that connects chain architecture, degradation chemistry, and operating windows supports mechanistically informed selection of catalysts, severity, and residence time, while recognizing that reported selectivity varies strongly with reactor configuration and feed heterogeneity and that focused comparative studies are required to validate quantitative structure to selectivity links. In European post consumer sorting chains, PS and PC are frequently handled as separate fractions or appear in residues with distinct processing routes, therefore they are not included in the polymer set analyzed here. Polystyrene and polycarbonate are outside the scope of this review because they are commonly handled as separate fractions and are typically optimized toward different product slates than the gas, oil, and wax focused pathways emphasized here. Full article

(This article belongs to the Special Issue Applied Chemistry in Europe, 2nd Edition)

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14 pages, 2325 KB

Open AccessArticle

Two Birds with One Stone: One-Pot Conversion of Waste Biomass into N-Doped Porous Biochar for Efficient Formaldehyde Adsorption

by Qingsong Zhao, Ning Xiang, Miao Xue, Chunlin Shang, Yiyi Li, Mengzhao Li, Qiqing Ji, Yangce Liu, Hongyu Hao, Zheng Xu, Fei Yang, Tiezheng Wang, Qiaoyan Li and Shaohua Wu

Molecules 2026, 31(2), 201; https://doi.org/10.3390/molecules31020201 - 6 Jan 2026

Abstract

Converting agricultural solid waste into porous biochar for HCHO adsorption is considered as a “two birds with one stone” strategy, which can achieve the environmental goal of “treating waste with waste”. Unfortunately, the HCHO adsorption performance of pristine biochar is generally unsatisfactory, which [...] Read more.

Converting agricultural solid waste into porous biochar for HCHO adsorption is considered as a “two birds with one stone” strategy, which can achieve the environmental goal of “treating waste with waste”. Unfortunately, the HCHO adsorption performance of pristine biochar is generally unsatisfactory, which is derived from its poor surface activity and insufficient number of pores. In this study, a series of nitrogen-doped porous biochars with adjustable N-containing groups and porosity were synthesized by one-step pyrolysis of melamine and waste jujube pit in different mass ratios (NBC-x, x represented the mass ratio of melamine to waste jujube pit, x = 4–12) for HCHO adsorption. The HCHO adsorption tests indicated that the insertion of nitrogen-containing species improved the adsorption capacity of pristine biochar (BC). However, after the insertion of excessive nitrogen-containing species, the porosity of the samples significantly decreased due to the blockage of pores, which could be disadvantageous for HCHO adsorption. DFT calculation results showed that N doping (especially pyrrolic-N) significantly increased the maxima of absolute ESP values of the carbonaceous models and consequently enhanced the affinity between polar HCHO and carbonaceous models (varied from −20.65 kJ/mol to −33.26 kJ/mol). Thus, the NBC-8 possessing both substantial nitrogen content (19.81 wt. %) and developed porosity (specific surface area of 223 m²/g) exhibited the highest HCHO uptake of 6.30 mg/g. This was approximately 6.4 times larger than that of BC. This work not only deepens the understanding of the HCHO adsorption mechanism at molecular scale, but also concurrently offers a facile and eco-friendly route of N-doped porous biochar preparation, an efficient technology with high-value utilization of waste biomass resources, and a sustainable method of pollution remediation. Full article

(This article belongs to the Special Issue Recent Advances in Porous Materials, 2nd Edition)

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3 pages, 156 KB

Open AccessEditorial

Computational Strategies Reshaping Modern Drug Discovery

by Marco Tutone and Anna Maria Almerico

Molecules 2026, 31(2), 200; https://doi.org/10.3390/molecules31020200 - 6 Jan 2026

Abstract

Conventional drug development remains a protracted [...] Full article

(This article belongs to the Special Issue Computational Approaches: Drug Discovery and Design in Medicinal Chemistry and Bioinformatics, 3rd Edition)

16 pages, 556 KB

Open AccessArticle

Chemoselectively Functionalized Ketoesters by Halogenative C–C Bond Cleavage of Cyclic Diketones

by Hideyasu China, Nami Kageyama, Hodaka Yatabe, Mihoyo Fujitaka, Yusei Matsumoto, Zhihan Jing and Toshifumi Dohi

Molecules 2026, 31(1), 199; https://doi.org/10.3390/molecules31010199 - 5 Jan 2026

Abstract

Haloketoesters are synthetic intermediates in various cyclization reactions that facilitate the production of biologically active compounds. Nonetheless, the selective synthesis of dihaloketoesters and trihaloketoesters, which are expected to be highly versatile, presents significant challenges. In this study, we designed a new synthetic approach [...] Read more.

Haloketoesters are synthetic intermediates in various cyclization reactions that facilitate the production of biologically active compounds. Nonetheless, the selective synthesis of dihaloketoesters and trihaloketoesters, which are expected to be highly versatile, presents significant challenges. In this study, we designed a new synthetic approach that selectively and efficiently produces haloketoesters through the halogenative C–C bond cleavage and ring-opening reactions of cyclic 1,3-diketones. This convenient method enables the direct synthesis of di- and trichloro-functionalized ketoesters from 1,3-cyclohexadiones under mild conditions. Na₂HPO₄, employed as a buffer salt, proved to be effective in facilitating the alcoholytic ring-opening reaction of 2,2-dichloro-1,3-cyclohexadiones, which were generated as synthetic intermediates. Full article

(This article belongs to the Special Issue Feature Papers in Organic Chemistry—Third Edition)

13 pages, 575 KB

Open AccessArticle

A Star-PEGylation Strategy to Improve Testosterone Pharmacokinetics

by Chae Bin Lee, Lukáš Tenora, Ruoning Zhang, Arina Ranjit, Mark C. Markowski, Barbara S. Slusher and Rana Rais

Molecules 2026, 31(1), 198; https://doi.org/10.3390/molecules31010198 - 5 Jan 2026

Abstract

Testosterone, an androgenic steroid hormone, regulates primary sexual characteristics and influences mood, cognition, social behavior, and sexual function. Deficiency, caused by factors such as aging and genetics, is linked to multiple disease conditions. However, current testosterone therapies are limited by extensive metabolism, poor [...] Read more.

Testosterone, an androgenic steroid hormone, regulates primary sexual characteristics and influences mood, cognition, social behavior, and sexual function. Deficiency, caused by factors such as aging and genetics, is linked to multiple disease conditions. However, current testosterone therapies are limited by extensive metabolism, poor solubility, and undesirable side effects. To address these limitations, we synthesized a four-armed star PEG-OH-linked testosterone (PEG-T). The in vitro release of testosterone from PEG-T was evaluated in buffer (pH 7.4) and mouse plasma. PEG-T was stable in the buffer, but released testosterone in plasma via esterase-mediated hydrolysis. Pharmacokinetics of testosterone and PEG-T were compared following intraperitoneal (IP) and subcutaneous (SC) administration. Following IP dosing, PEG-T exhibited a ~6-fold improvement in half-life compared to testosterone (1.18 h vs. 0.21 h), and a 54-fold increase in exposure (AUC_0-t = 36.0 μM·h vs. 0.67 μM·h) at equimolar doses; furthermore, following SC dosing, PEG-T showed a 4-fold improvement in both half-life (3.57 h vs. 0.91 h) and plasma exposure (11.5 μM·h vs. 3.1 μM·h). Additionally, PEG-T showed lower liver and kidney to plasma ratios, which could potentially result in reduced hepatotoxicity and nephrotoxicity. Overall, PEG-T provides sustained release pharmacokinetics, representing a promising candidate for safer testosterone replacement therapy. Full article

(This article belongs to the Section Medicinal Chemistry)

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22 pages, 363 KB

Open AccessArticle

Bioactive Phytocompound Profiling and the Evaluation of Antioxidant, Antihyperglycemic, and Antimicrobial Activities of Medicinal Plants from Serbian Traditional Medicine

by Milica Aćimović, Anja Vučetić, Jelena Vulić, Aleksandra Ranitović, Teodora Marić, Vanja Travičić and Olja Šovljanski

Molecules 2026, 31(1), 197; https://doi.org/10.3390/molecules31010197 - 5 Jan 2026

Abstract

Medicinal plants represent an important source of bioactive compounds whose composition and biological activity are strongly influenced by geographical origin and extraction conditions. In this study, six medicinal plants traditionally used in south-eastern Serbia (Galium verum, Filipendula vulgaris, Lythrum salicaria [...] Read more.

Medicinal plants represent an important source of bioactive compounds whose composition and biological activity are strongly influenced by geographical origin and extraction conditions. In this study, six medicinal plants traditionally used in south-eastern Serbia (Galium verum, Filipendula vulgaris, Lythrum salicaria, Sideritis montana, Teucrium chamaedrys, and Teucrium montanum) were investigated for their phytochemical composition and antioxidant, antihyperglycemic, and antimicrobial activities. Aqueous and 40% ethanol extracts were prepared and analyzed for total phenolic content (TPC) and total flavonoid content (TFC), followed by HPLC-DAD profiling of individual polyphenolic compounds. Antioxidant activity was assessed using DPPH, ABTS, and reducing power assays, antihyperglycemic activity by α-glucosidase inhibition, and antimicrobial activity by the microdilution method against selected bacterial and fungal strains. L. salicaria exhibited the highest TPC (113.56–119.09 mg GAE/g DW), while F. vulgaris showed the highest TFC (65.74–66.31 mg RE/g DW). HPLC analysis revealed notable levels of ferulic acid in L. salicaria ethanol extract (39.12 mg/g DW), as well as rutin, luteolin, and myricetin in several species. Ethanol extracts generally demonstrated stronger antioxidant activity, with L. salicaria showing the highest DPPH (378.60 µM TE/g) and reducing power (684.06 µM TE/g), while its aqueous extract exhibited the highest ABTS activity (3621.93 µM TE/g). Strong antihyperglycemic activity was observed for F. vulgaris extracts (100% α-glucosidase inhibition). Antimicrobial assays revealed higher sensitivity of Gram-positive bacteria, particularly Listeria monocytogenes and Staphylococcus aureus, with F. vulgaris and L. salicaria extracts showing the strongest effects. These findings highlight the significant influence of plant species and extraction solvent on bioactivity and support the potential of selected Serbian medicinal plants as sources of multifunctional natural bioactive compounds. Full article

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19 pages, 6411 KB

Open AccessArticle

Viniferin-Rich Phytocomplex from Vitis vinifera L. Plant Cell Culture Mitigates Neuroinflammation in BV2 Microglia Cells

by Giacomina Videtta, Chiara Sasia, Sofia Quadrino, Oriana Bertaiola, Chiara Guarnerio, Elisa Bianchi, Giacomo Biagiotti, Barbara Richichi, Stefano Cicchi, Giovanna Pressi and Nicoletta Galeotti

Molecules 2026, 31(1), 196; https://doi.org/10.3390/molecules31010196 - 5 Jan 2026

Abstract

Activation of microglia and resulting neuroinflammation are central processes that significantly contribute to neurodegenerative disease progression. Treatments capable of attenuating neuroinflammation are therefore an urgent medical need. Vitis vinifera L., cultivated since ancient times for its fruits, is known for its antioxidant and [...] Read more.

Activation of microglia and resulting neuroinflammation are central processes that significantly contribute to neurodegenerative disease progression. Treatments capable of attenuating neuroinflammation are therefore an urgent medical need. Vitis vinifera L., cultivated since ancient times for its fruits, is known for its antioxidant and anti-inflammatory activities. However, polyphenols, the main bioactive molecules in V. vinifera extracts, exhibit considerable variability due to numerous hard-to-control factors, which complicates the production of standardized extracts with consistent biological activity. To address this issue, plant cell culture biotechnology was used to produce a highly standardized V. vinifera phytocomplex (VP), and its anti-neuroinflammatory profile was investigated in LPS-stimulated microglial cells, an in vitro model of neuroinflammation. VP reduced the LPS-induced pro-inflammatory phenotype, improved cell viability and cell number, attenuated NF-κB activation and ERK1/2 phosphorylation, and increased SIRT1 levels. To overcome VP’s poor water solubility, water-soluble cellulose nanocrystal (CNC)-based formulations were developed and tested. VP-CNC formulations markedly reduced the BV2 pro-inflammatory phenotype and increased cell viability under both basal and LPS-stimulated conditions. The nanoformulations also decreased pERK1/2 levels and increased SIRT1 expression, exhibiting biological activities comparable to VP alone. V. vinifera phytocomplex derived from plant cell cultures represents an innovative and standardized product with promising anti-neuroinflammatory properties. Full article

(This article belongs to the Special Issue Medicinal Value of Natural Bioactive Compounds and Plant Extracts, 3rd Edition)

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19 pages, 6312 KB

Open AccessArticle

Antioxidant, Anti-Inflammatory, and Chemical Composition Analysis of In Vitro Huperzia serrata Thallus and Wild Huperzia serrata

by Yongchun Huang, Xinyuan Li, Liangfang Dai, Malong Cheng, Linlin Zhao, Yu Shen, Jiankun Xie and Xiangdong Luo

Molecules 2026, 31(1), 195; https://doi.org/10.3390/molecules31010195 - 5 Jan 2026

Abstract

Huperzine A is a preferred treatment option for Alzheimer’s disease. Huperzia serrata (Thunb. ex Murray) Trev. (H. serrata) has garnered significant attention for its ability to produce Huperzine A (HupA). However, natural populations of wild H. serrata (WH) are rapidly declining. [...] Read more.

Huperzine A is a preferred treatment option for Alzheimer’s disease. Huperzia serrata (Thunb. ex Murray) Trev. (H. serrata) has garnered significant attention for its ability to produce Huperzine A (HupA). However, natural populations of wild H. serrata (WH) are rapidly declining. Fortunately, our group obtained two types of H. serrata thalli (OT and ST) capable of stably producing Huperzine A, which have the potential to serve as an alternative resource to WH. To evaluate the feasibility of this strategy, we conducted a comprehensive assessment of both WH and H. serrata thallus. The results indicated that compared to WH, ST and OT exhibited stronger anti-inflammatory and antioxidant activities, with lower cytotoxicity. Notably, ST demonstrated a strong radical scavenging activity, reaching 93.23% (DPPH at 0.2 μg/mL) and 99.87% (ABTS at 4 μg/mL), and reduced nitrite production from 10.29 μM to 6.51 μM at 50 µg/mL. GC-MS and widely targeted metabolomics analyses revealed that the higher antioxidant and anti-inflammatory activities for ST and OT were due to higher concentrations of phenolic acids and flavonoids compared to WH. In addition, the HupA content in ST reached 36.56% of that found in WH. KEGG enrichment analysis revealed that the flavonoid, phenylalanine, and phenylpropanoid biosynthesis pathways may be involved in regulating the antioxidant activity. P-coumaroyl quinic acid and caffeoyl quinic acid are the crucial metabolites for antioxidant activity. These findings suggested that the H. serrata thallus could serve as a sustainable alternative to WH. Full article

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16 pages, 5636 KB

Open AccessArticle

Natural Polyphenol Corilagin Enhances Osteogenesis and Chondrogenesis Differentiation of Mesenchymal Stem Cells: Implications for Bone and Cartilage Regeneration

by Thitianan Kulsirirat, Sittisak Honsawek, Mariko Takeda-Morishita and Korbtham Sathirakul

Molecules 2026, 31(1), 194; https://doi.org/10.3390/molecules31010194 - 5 Jan 2026

Abstract

Corilagin is a hydrolyzable ellagitannin and naturally occurring polyphenolic compound widely distributed in medicinal plants. It is also present in longan (Dimocarpus longan), known as lumyai in Thailand, a subtropical fruit extensively cultivated across China and Southeast Asia. Corilagin has been [...] Read more.

Corilagin is a hydrolyzable ellagitannin and naturally occurring polyphenolic compound widely distributed in medicinal plants. It is also present in longan (Dimocarpus longan), known as lumyai in Thailand, a subtropical fruit extensively cultivated across China and Southeast Asia. Corilagin has been reported to exhibit strong antioxidant, anti-inflammatory, hepatoprotective, and anticancer activities through modulation of multiple cellular signaling pathways. However, despite these well-established pharmacological properties, its potential role in regulating bone marrow mesenchymal stem cell (BM-MSC) differentiation has not been fully explored in biomedical applications. In this study, we investigated the effects of corilagin on BM-MSC viability, protein-binding interactions, and lineage-specific differentiation toward osteogenic and chondrogenic pathways. Cytotoxicity assessment using human synovial SW-982 cells demonstrated that corilagin maintained cell viability at concentrations ranging from 1.56 to 50 µg/mL within 48 h, whereas prolonged exposure resulted in a time-dependent reduction in viability. In BM-MSCs, corilagin significantly enhanced osteogenic and chondrogenic differentiation in a dose-dependent manner, as evidenced by increased mineral deposition and cartilage matrix formation, as revealed by Alizarin Red S, Toluidine Blue, and Alcian Blue staining. Quantitative analyses further showed the upregulation of key lineage-specific genes, including Runx2 and osteopontin (OPN) for osteogenesis and Sox9 and aggrecan for chondrogenesis. Protein-binding assays confirmed the molecular interaction capacity of corilagin, supporting its biological activity. Overall, these findings demonstrate that corilagin promotes MSC-mediated osteogenic and chondrogenic differentiation while maintaining acceptable cytocompatibility, highlighting its potential as a natural small-molecule candidate for bone and cartilage tissue engineering and other biomedical fields with regenerative medicine applications. Full article

(This article belongs to the Special Issue Natural Bioactive Compounds from Traditional Asian Plants—Second Edition)

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16 pages, 2897 KB

Open AccessArticle

Diphosphine-Substituted Rhodium Carbonyl Clusters: Synthesis and Structural and Spectroscopic Characterization of the Heteroleptic Rh₄(CO)_8+2n(L)_2−n (n = 0, 1) and {Rh₄(CO)₁₀L}₂ Monomeric and Dimeric Species

by Giorgia Scorzoni, Guido Bussoli, Cristiana Cesari, Maria Carmela Iapalucci, Stefano Zacchini and Cristina Femoni

Molecules 2026, 31(1), 193; https://doi.org/10.3390/molecules31010193 - 5 Jan 2026

Abstract

Tetranuclear rhodium carbonyl clusters are vital catalytic precursors; yet derivatives featuring bidentate phosphines are less common, due to the propensity for cluster fragmentation during synthesis. This study reports the successful isolation of five new heteroleptic species by reacting Rh₄(CO)₁₂ with [...] Read more.

Tetranuclear rhodium carbonyl clusters are vital catalytic precursors; yet derivatives featuring bidentate phosphines are less common, due to the propensity for cluster fragmentation during synthesis. This study reports the successful isolation of five new heteroleptic species by reacting Rh₄(CO)₁₂ with various bidentate diphosphines under homogeneous conditions and at room temperature, namely the mono-substituted Rh₄(CO)₁₀(dppe) (1) and Rh₄(CO)₁₀(dppb) (3), the rare bis-substituted derivative Rh₄(CO)₈(dppe)₂ (2), and the two unique dimeric assemblies {Rh₄(CO)₁₀(dpp-hexane)}₂ (4) and {Rh₄(CO)₁₀(trans-dppe)}₂ (5). The tetrahedral Rh₄ core of the cluster precursor was preserved in all cases. The new compounds were characterized via infrared (IR) spectroscopy and single-crystal X-ray diffraction (SC-XRD). Furthermore, variable-temperature (VT) ³¹P{¹H} NMR spectroscopy elucidated the dynamic behavior of the phosphorus atoms. This work reports a robust methodology for accessing stable, low-nuclearity rhodium phosphine clusters with tunable properties. Full article

(This article belongs to the Section Inorganic Chemistry)

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24 pages, 666 KB

Open AccessReview

Green Extraction at Scale: Hydrodynamic Cavitation for Bioactive Recovery and Protein Functionalization—A Narrative Review

by Francesco Meneguzzo, Federica Zabini and Lorenzo Albanese

Molecules 2026, 31(1), 192; https://doi.org/10.3390/molecules31010192 - 5 Jan 2026

Abstract

Hydrodynamic cavitation (HC) is a green and readily scalable platform for the recovery and upgrading of bioactives from agri-food and forestry byproducts. This expert-led narrative review examines HC processing of citrus and pomegranate peels, softwoods, and plant protein systems, emphasizing process performance, ingredient [...] Read more.

Hydrodynamic cavitation (HC) is a green and readily scalable platform for the recovery and upgrading of bioactives from agri-food and forestry byproducts. This expert-led narrative review examines HC processing of citrus and pomegranate peels, softwoods, and plant protein systems, emphasizing process performance, ingredient functionality, and realistic routes to market, and contrasts HC with other green extraction technologies. Pilot-scale evidence repeatedly supports water-only operation with high solids and short residence times; in most practical deployments, energy demand is dominated by downstream water removal rather than the extraction step itself, which favors low water-to-biomass ratios. A distinctive outcome of HC is the spontaneous formation of stable pectin–flavonoid–terpene phytocomplexes with improved apparent solubility and bioaccessibility, and early studies indicate that HC may also facilitate protein–polyphenol complexation while lowering anti-nutritional factors. Two translational pathways appear near term: (i) blending HC-derived dry extracts with commercial dry protein isolates to deliver measurable functional benefits at low inclusion levels and (ii) HC-based extraction of plant proteins to obtain digestion-friendly isolates and conjugate-ready ingredients. Priority gaps include harmonized reporting of specific energy consumption and operating metrics, explicit solvent/byproduct mass balances, matched-scale benchmarking against subcritical water extraction and pulsed electric field, and evidence from continuous multi-ton operation. Overall, HC is a strong candidate unit operation for circular biorefineries, provided that energy accounting, quality retention, and regulatory documentation are handled rigorously. Full article

(This article belongs to the Special Issue Bioproducts for Health, 4th Edition)

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14 pages, 4531 KB

Open AccessReview

Quantitative Surface-Enhanced Raman Spectroscopy: Challenges, Strategies, and Prospects

by Zhixuan Lu, Jun Wang and Sen Yan

Molecules 2026, 31(1), 191; https://doi.org/10.3390/molecules31010191 - 5 Jan 2026

Abstract

Surface-Enhanced Raman Spectroscopy (SERS) is highly attractive as an analytical technique owing to its high sensitivity, distinctive molecular specificity, and speed of analysis. It offers the potential to match the sensitivity and molecular specificity of established techniques like Gas Chromatography–Mass Spectrometry in a [...] Read more.

Surface-Enhanced Raman Spectroscopy (SERS) is highly attractive as an analytical technique owing to its high sensitivity, distinctive molecular specificity, and speed of analysis. It offers the potential to match the sensitivity and molecular specificity of established techniques like Gas Chromatography–Mass Spectrometry in a more affordable, faster, and portable format, providing unique solutions for challenging analytical problems such as bedside diagnostics and in-field forensic analysis. Despite these benefits, SERS currently remains a specialized technique and has not yet successfully entered the mainstream of analytical chemistry. This transition is hindered primarily by challenges in achieving robust, reliable, and especially quantitative measurements in real-world applications. Achieving quantitative SERS requires addressing core issues arising from the heterogeneous nature of enhancing substrates and the complexity of real-life samples. This perspective summarizes the fundamental challenges associated with signal variability and matrix interference. It then details modern strategies focused on standardizing performance metrics, with particular emphasis on the newly proposed SERS Performance Factor for substrate evaluation, alongside the development of advanced quantification methods (e.g., internal standardization and digital SERS) and rapid sample pretreatment protocols. Finally, emerging prospects, including the deployment of Artificial Intelligence for enhanced analysis and advancements in deep-tissue SERS sensing, are explored as critical drivers for integrating SERS into routine analytical practice. Full article

(This article belongs to the Section Analytical Chemistry)

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15 pages, 3557 KB

Open AccessArticle

Obtaining and Studying the Properties of Composite Materials from ortho-, meta-, para-Carboxyphenylmaleimide and ABS

by Eldar Garaev, Shahana Guliyeva, Aygun Alikhanova, Konul Huseynguliyeva and Bakhtiyar Mammadov

Molecules 2026, 31(1), 190; https://doi.org/10.3390/molecules31010190 - 5 Jan 2026

Abstract

This work presents the results of the synthesis and investigation of new antibacterial composite materials based on acrylonitrile–butadiene–styrene (ABS) copolymer and o-, m-, p-carboxyphenylmaleimides (CPhMI). The composites were obtained by thermal mixing with varying contents of different CPhMI isomers in [...] Read more.

This work presents the results of the synthesis and investigation of new antibacterial composite materials based on acrylonitrile–butadiene–styrene (ABS) copolymer and o-, m-, p-carboxyphenylmaleimides (CPhMI). The composites were obtained by thermal mixing with varying contents of different CPhMI isomers in the polymer matrix. The structural and thermal characteristics of the synthesized materials were investigated using IR and UV spectroscopy, as well as thermogravimetric (TGA) and differential thermal analysis (DTA). The results indicate that the o-isomer imparts the highest thermal stability, while the p-isomer shows slightly lower stability. In terms of processability, the m-isomer exhibits the highest melt flow, the p-isomer an intermediate level, and the o-isomer the lowest. The antibacterial activity of the composites was evaluated by the agar diffusion method against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms. All synthesized samples exhibited strong antibacterial activity against S. aureus and E. coli at a concentration of 0.5 wt%, confirming their potential for application in medical devices, as well as in sanitary polymer coatings and packaging. Full article

(This article belongs to the Section Macromolecular Chemistry)

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17 pages, 854 KB

Open AccessArticle

Influence of Coexisting Copper and Zinc on the Adsorption and Migration of Sulfadiazine in Soda Saline–Alkali Wetland Soils: A Simulation Approach

by Wencong Yang, Xia Wu, Wenyue Shao, Nana Luo and Jia Zhou

Molecules 2026, 31(1), 189; https://doi.org/10.3390/molecules31010189 - 5 Jan 2026

Abstract

This study investigates the adsorption and migration of sulfadiazine (SDZ) in soda saline–alkali soils under Cu/Zn co-pollution using equilibrium adsorption and soil column experiments. Freundlich and Langmuir isothermal models, combined with Hydrus-1D two-site modeling, revealed concentration-dependent interactions. Low Cu (10–100 mg kg⁻¹ [...] Read more.

This study investigates the adsorption and migration of sulfadiazine (SDZ) in soda saline–alkali soils under Cu/Zn co-pollution using equilibrium adsorption and soil column experiments. Freundlich and Langmuir isothermal models, combined with Hydrus-1D two-site modeling, revealed concentration-dependent interactions. Low Cu (10–100 mg kg⁻¹) and Zn (10–100 mg kg⁻¹) enhanced SDZ adsorption via charge regulation and complexation, while high concentrations (300 mg kg⁻¹) suppressed adsorption through competitive adsorption and hydroxide precipitation. Synergistic Cu-Zn coexistence further reduced adsorption to 3.035 mg kg⁻¹. Freundlich modeling (R² = 0.922–0.995) outperformed Langmuir, confirming adsorption site heterogeneity. Column experiments showed Cu (300 mg kg⁻¹) and Zn (300 mg kg⁻¹) accelerated SDZ migration (peaks 0.93–0.94), delaying breakthrough versus Br⁻. Hydrus-1D simulations (R² ≥ 0.915, RMSE < 0.1) effectively quantified nonlinear dynamics between instantaneous adsorption sites (f = 0.101–0.554) and metal concentrations. Results demonstrate heavy metals critically regulate antibiotic fate via concentration-dependent mechanisms in saline–alkali ecosystems. Full article

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19 pages, 2663 KB

Open AccessArticle

Enhancing Antioxidant and Flavor of Xuanwei Ham Bone Hydrolysates via Ultrasound and Microwave Pretreatment: A Backpropagation Artificial Neural Network Model Prediction

by Xin Chen, Xianchao Feng, Xingwei Wang, Nianwen Zhang, Yuxia Jin, Jianxin Cao, Xuejiao Wang and Chaofan Guo

Molecules 2026, 31(1), 188; https://doi.org/10.3390/molecules31010188 - 4 Jan 2026

Abstract

This study aimed to produce the hydrolysates of Xuanwei ham bone using enzymatic hydrolysis assisted by microwave and ultrasound pretreatment. A back propagation artificial neural network (BP-ANN) model was utilized to predict the optimal conditions, which involved 15 W/g bone for 15 min [...] Read more.

This study aimed to produce the hydrolysates of Xuanwei ham bone using enzymatic hydrolysis assisted by microwave and ultrasound pretreatment. A back propagation artificial neural network (BP-ANN) model was utilized to predict the optimal conditions, which involved 15 W/g bone for 15 min of ultrasound pretreatment and 5 W/g bone for 30 min of microwave pretreatment, achieving the highest degree of hydrolysis (DH). The model predicted a DH of 27.69, closely aligning with the experimentally measured actual DH of 28.33. DPPH radical scavenging and TBARS demonstrated that hydrolysates prepared by ultrasound combined microwave pretreatment (UMH) exhibited the highest antioxidant activity and significantly inhibited lipid oxidation. GC-MS analysis revealed that the UMH showed removal of bitter volatile flavor compounds, such as o-Cresol and m-Cresol, the retention of aromatic volatile compounds, such as 2-pentylfuran, formation of new aromatic volatile compounds such as 3-methylbutanal, and the reduction in certain aldehyde and ketone compounds. Pearson correlation analysis elucidated that the reduction in aldehyde and ketone compounds was positively linked to the enhanced antioxidant capacity of UMH. The results obtained hold substantial significance for enhancing the added value of Xuanwei ham within the food industry. Full article

(This article belongs to the Special Issue Chemical Transformations and Analysis in Food: Nutrition, Flavor Compounds, and Microbiological Research)

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26 pages, 4087 KB

Open AccessReview

Oxime Esters as Efficient Initiators in Photopolymerization Processes

by Monika Dzwonkowska-Zarzycka, Alicja Balcerak-Woźniak and Janina Kabatc-Borcz

Molecules 2026, 31(1), 187; https://doi.org/10.3390/molecules31010187 - 4 Jan 2026

Abstract

The development of new photoinitiators for photocurable systems has gained increasing interest in response to regulatory and environmental requirements, including efficient absorption in the UV/Vis range and reduced toxicity. Among emerging light-sensitive compounds, oxime esters have attracted growing attention as efficient radical photoinitiators. [...] Read more.

The development of new photoinitiators for photocurable systems has gained increasing interest in response to regulatory and environmental requirements, including efficient absorption in the UV/Vis range and reduced toxicity. Among emerging light-sensitive compounds, oxime esters have attracted growing attention as efficient radical photoinitiators. In this paper, five series of oxime esters based on carbazole, coumarin, carbazole–coumarin, phenothiazine, and triphenylamine scaffolds were described. Their high performance in photopolymerization processes was presented, demonstrating their ability to act as both type I and type II photoinitiators, as confirmed by high monomer conversion degrees. These data highlight oxime esters as versatile photoinitiating systems and provide a basis for further structural optimization aimed at improving water solubility and enabling comprehensive cytotoxicity assessment. Full article

(This article belongs to the Topic Science and Technology of Polymeric Blends, Composites, and Nanocomposites)

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22 pages, 4820 KB

Open AccessArticle

Evaluation of Pyrrole Heterocyclic Derivatives as Selective MAO-B Inhibitors and Neuroprotectors

by Maya Georgieva, Martin Sharkov, Emilio Mateev, Alexandrina Mateeva and Magdalena Kondeva-Burdina

Molecules 2026, 31(1), 186; https://doi.org/10.3390/molecules31010186 - 4 Jan 2026

Abstract

Novel pyrrole-based derivatives were synthesized in high purity and yields (52–89%), with 17i and 17j displaying selective MAO-B inhibition (50–60%), comparable to Selegiline, and negligible MAO-A activity. In rat brain subcellular fractions, both compounds showed low intrinsic neurotoxicity at 100 μM while exerting [...] Read more.

Novel pyrrole-based derivatives were synthesized in high purity and yields (52–89%), with 17i and 17j displaying selective MAO-B inhibition (50–60%), comparable to Selegiline, and negligible MAO-A activity. In rat brain subcellular fractions, both compounds showed low intrinsic neurotoxicity at 100 μM while exerting significant neuroprotective and antioxidant effects under 6-OHDA, t-BuOOH, and Fe²⁺/ascorbate-induced stress. Mechanistic studies indicate dual protection via reactive oxygen species scavenging and preservation of reduced glutathione, with mitochondria and microsomes being the most responsive compartments. The performed in silico analysis revealed no general toxicity alerts, though hydrazine groups classify the compounds as contact allergens, and the furan ring in 17i poses hepatotoxic and carcinogenic risks. Metabolic predictions suggest ester hydrolysis at the pyrrole ring as the main biotransformation pathway. Overall, 17i and 17j are promising lead compounds for developing therapeutics targeting oxidative stress-related neurodegenerative diseases, such as Parkinson’s and Alzheimer’s, supporting further in vivo studies. Full article

(This article belongs to the Special Issue Advances in Synthesis and Biological Activity of Novel Derivatives Based on Five-Membered Heterocyclic Scaffolds and Their Intermediates, 3rd Edition)

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