The development of collagen hydrogels with tailored properties for improved applications in biomedicine represents an area of opportunity for materials science. The collagen can form semi-interpenetrated networks (semi-IPN) with various natural and/or synthetic polymers. This work aims the preparation of novel hydrogels generated from a collagen matrix cross-linked with polyurethane (PU), and the subsequent inclusion of polysaccharide chains to form semi-IPN systems with improved properties. The choice of polysaccharides for this purpose is related to their ability to modulate the biocompatibility and the antibacterial capacity in various biomedical strategies. The work

In this paper, we present a brief review of quinoid systems, focusing on their chemical synthesis over the last decade. We address not only major methods of synthesizing quinoids, but also their involvement in biological processes. We highlight their medical relevance and versatility, including antitumor, antiretroviral, or antihypertensive agents, properties determined by their various patterns of substitution. Graphical AbstractKeywords Quinone Á Synthesis Á Cytotoxicity Á Natural products Á Pharmacology Á Redox Abbreviations 3a-HSD 3a-Hydroxysteroid dehydrogenase AIDS Acquired Immune Deficiency Syndrome AlnA Alnumycin A AlnB Alnumycin B BAQ Benzanthracene quinone (7,12-benzo[a] anthraquinone) BPQ Benzo[a]pyrene-7,8-dione CAN Ceric ammonium nitrate CC 50 50 % Cytotoxic concentration CDC25 Cell division cycle phosphatases Cyt Ferricytochrome d-A 2 0 -Deoxyadenosine DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene DDQ 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone d-G, d-Guo 2'-Deoxyguanosine DMF N,N-dimethylformamide DMP Dess-Martin periodinane DMSO

In this work, a series of phenacyl bromide derivatives was synthesized and employed as key intermediate for the synthesis of substituted imidazo [1,2-a]pyridines. First, phenacyl bromide molecules were obtained from the bromination reaction of acetophenones assisted by microwave irradiation, obtaining the products 4a-v in a 15 minutes reaction with yields in the range of 50% to 99%. Subsequently, the conjugation of these molecules with 2-aminopyridine conduced to the production of imidazo[1,2-a]pyridine derivatives (7a-v) in a 60-second reaction with yields of 24% to 99%. Improved yields were determined with respect to those obtained with more tedious methodologies like thermally and mechanically assisted routes. Intense luminescence emissions in the purple and blue regions of the electromagnetic spectra were observed under UV excitation according to the nature of the substituents. This environmentally friendly methodology is expected to constitute an important class of organic compounds for the development of biomarkers, photochemical sensors, and medicinal applications.

The development of practical and sensitive tools for detecting phosphate deficiency could facilitate engineering approaches to enhance crop yield and quality in phosphate-stressed environments, reducing the misuse of nonrenewable fertilizers and their consequent ecological impact. Herein, a 975 nm-activated method based on ZrO2:Yb,Er@ZrO2 core@shell upconversion nanoparticles is presented for rapid visualization and determination of the phosphate ions in aqueous solutions and extracts. At optimized thickness, the nondoped ZrO2 shell not only enhances the emission of the ZrO2:Yb,Er but also provides an active surface for the intense interaction with the phosphate group, allowing a “label-free” determination that avoids the use of additional phosphate-recognizing elements like ligands or antibodies. According to the experimental evidence, the optical output of the ZrO2:Yb,Er@ZrO2 nanoparticles specifically matches with the absorption spectrum of the fast green alimentary dye (FG) electrostatically attached to the nanoparticle surface, activating the Förster resonance energy transfer (FRET) and thereby the upconversion luminescence quenching. Upon addition of the phosphate ions and the covalent interaction with the ZrO2:Yb,Er@ZrO2–FG nanocomplex, the FG is gradually removed, displaying a fast and reproducible “turn-on” luminescence which allows measurements in a few minutes. This rapid response is due to the stronger coordination between the ZrO2 shell and the phosphate compared to the FG molecules (−31.97 and −5.99 eV, respectively). The detection method was then effectively modulated in a 20–1000 nM linear response range without interfering effects of commonly coexisting ions, achieving a detection limit up to 15 times lower than that obtained with the conventionally used colorimetric methods.

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An efficient and simple synthesis of novel and densely substituted N-benzyl-1H-pyrroles 6a-r is described by a 1,4-addition/isomerization/ring closure/demetalation cascade process of alkynyl Fischer carbene complexes 1a-f and 2a and α-imino glycine methyl esters 3a, b, d, g, h, and k promoted with LDA.

The unprecedented reaction of ketone‐containing aromatic pyridinium salts 3a‐e and alkynyl Fischer complexes 1a‐f proceeds via a mild domino process to provide 4,6‐disubstituted pyran‐2‐ones 5a‐k and 2,3,5‐trisubstituted furans 6a‐h (45‐97%). According of the results of isotopic labeling experiments, a mechanism involving an initial Michael addition appears to be the key step, obtaining a mesomeric structure responsible for the formation of both products.

A series of 2,4,6-trisubstituted phenols 7a-7p has been prepared in moderate to good yields (23-77 %) by a retroDiels-Alder reaction from hindered tricyclic alcohols 6a-6q, using mild acidic conditions. The tricyclic alcohols were obtained by reduction of highly functionalized cyclohexadienones 5a-5q, which in turn were regioselectively prepared under mild conditions in high yields by treatment of a series of stable chromium(0) and tungsten(0) Fischer dienyl carbenes 4a-4g with different terminal alkynes 3a-3l. Carbenes 4a-4g were pre-