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1.
Angew Chem Int Ed Engl ; : e202412922, 2024 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-39175166

RESUMEN

Chalcogens are used as sensitive redox-responsive reagents in tumor therapy. However, chalcogen bonds triggered by external ionizing radiation, rather than by internal environmental stimuli, enable site-directed and real-time drug degradation in target lesions. This approach helps to bypass chemoresistance and global systemic toxicity, presenting a significant advancement over traditional chemoradiotherapy. In this study, we fabricated a hybrid monodisperse organosilica nanoprodrug based on homonuclear single bonds (disulfide bonds (S-S, approximately 240 kJ/mol), diselenium bonds (Se-Se, approximately 172 kJ/mol), and tellurium bonds (Te-Te, 126 kJ/mol)), including ditelluride-bond-bridged MONs (DTeMSNs), diselenide-bond-bridged MONs (DSeMSNs) and disulfide-bond-bridged MONs (DSMSNs). The results demonstrated that differences in electronegativities and atomic radii influenced their oxidation sensitivities and reactivities. Tellurium, with the lowest electronegativity, showed the highest sensitivity, followed by selenium and sulfur. DTeMSNs exhibited highly responsive cleavage upon exposure to X-rays, resulting in oxidation to TeO32-. Furthermore, chalcogen-hybridized organosilica was loaded with manganese ions (Mn2+) to enhance the release of Mn2+ during radiotherapy, thereby activating the the stimulator of interferon genes (STING) pathway and enhancing the tumor immune response to inhibit tumor growth. This investigation of hybrid organosilica deepens our understanding of chalcogens response characteristics to radiotherapy and enriches the design principles for nanomedicine based on prodrugs.

2.
Angew Chem Int Ed Engl ; 63(27): e202401020, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38632078

RESUMEN

Singlet carbenes are not always isolable and often even elude direct detection. When they escape observation, their formation can sometimes be evidenced by in situ trapping experiments. However, is carbene-like reactivity genuine evidence of carbene formation? Herein, using the first example of a spectroscopically characterized cyclic (amino)(aryl)carbene (CAArC), we cast doubt on the most common carbene trapping reactions as sufficient proof of carbene formation.

3.
Chemistry ; 30(36): e202400850, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38656583

RESUMEN

The stable ferrocene-based N-heterocyclic silylenes fc[(N{B})2Si] (A; fc=1,1'-ferrocenylene, {B}=(HCNDipp)2B, Dipp=2,6-diisopropylphenyl) and fc[(NDipp)2Si] (B) are compared in a study focussing on their reactivity towards a range of small to moderately sized molecular substrates, viz. P4, S8, Se8, MesN3 (Mes=mesityl), RC≡CH, and RC≡CR (R=Ph, SiMe3). The Dipp-substituted congener B exhibits a more pronounced ambiphilicity and is sterically less congested than its 1,3,2-diazaborolyl-substituted relative A, in line with the higher reactivity of the former. The difference in reactivity is obviously due more to electronic than to steric reasons, as is illustrated by the fact that both A and B react with the comparatively bulky substrate MesN3 under mild conditions to afford the corresponding silanimine fc[(N{B})2Si=NMes] and fc[(NDipp)2Si=NMes], respectively. The heavier ketone analogues fc[(N{B})2Si=E] (E=S, Se, Te) are readily available from A and the corresponding chalcogen. In contrast, the reaction of the more reactive silylene B with elemental sulfur or selenium is unspecific, affording product mixtures. However, fc[(NDipp)2Si=Se] is selectively prepared from B and (Et2N)3PSe; the Te analogue is also accessible, but crystallises as head-to-tail dimer.

4.
Beilstein J Org Chem ; 20: 287-305, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38379731

RESUMEN

The "precursor approach" has proved particularly valuable for the preparation of insoluble and unstable π-conjugated polycyclic compounds (π-CPCs), which cannot be synthesized via in-solution organic chemistry, for their improved processing, as well as for their electronic investigation both at the material and single-molecule scales. This method relies on the synthesis and processing of soluble and stable direct precursors of the target π-CPCs, followed by their final conversion in situ, triggered by thermal activation, photoirradiation or redox control. Beside well-established reactions involving the elimination of carbon-based small molecules, i.e., retro-Diels-Alder and decarbonylation processes, the late-stage extrusion of chalcogen fragments has emerged as a highly promising synthetic tool to access a wider variety of π-conjugated polycyclic structures and thus to expand the potentialities of the "precursor approach" for further improvements of molecular materials' performances. This review gives an overview of synthetic strategies towards π-CPCs involving the ultimate elimination of chalcogen fragments upon thermal activation, photoirradiation and electron exchange.

5.
Chemistry ; 30(19): e202304183, 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38240709

RESUMEN

The electrophilic functionalization of the triple-decker sandwich complex [{Cp*Mo}2(µ,η6:6-P6)] (A) and its mono-oxidized counterpart [{Cp*Mo}2(µ,η6:6-P6)][SbF6] (B) with reactive main-group electrophiles as well as radical scavengers is shown to be a reliable method for the selective functionalization of the hexaphosphabenzene ligand. Depending on the electrophile used, the regioselectivity of the functionalization can be adjusted. Using group 16 electrophiles, the trisubstituted compounds [{Cp*Mo}2{(µ,η3 : 3-P3)(µ,η1 : 1 : 1 : 1-1,3-(SePh)2-2-Br-P3)}][TEF] (1), [{Cp*Mo}2(µ,η3 : 3-P3)(µ,η1 : 1 : 1 : 1-1,2,3-(EPh)3-P3)][SbF6] (E=S (2), Se (3)) as well as the side product [{Cp*Mo}2(µ,η4:4-P4)(µ,η1 : 1-P(SPh)2)][SbF6] (4) are obtained. By switching to phosphenium ions as group 15 electrophiles, the ring-inserted products [{Cp*Mo}2(µ,η3 : 3 : 2 : 2-P7R2)][TEF] (R=Cy (5), iPr (6)) are isolated, showing an unprecedented P7R2 structural motif. Furthermore, the reaction with MeOTf yields the dimeric [{Cp*Mo}4(1,4-Me2-µ4,η1 : 1 : 1 : 1 : 1 : 1-P6)(µ,η3 : 3-P3)2][TEF]2 (7) as the first example of a complex featuring two interconnected cyclo-P6 middle deck ligands. Finally, by combination of the methylation step with Ph2Se2, the mixed group 14/16 complex [{Cp*Mo}2{(µ,η3 : 3-P3)(µ,η1 : 1 : 1 : 11,2-(SePh)2-3-Me-P3)}][OTf] (8) is obtained.

6.
Chemistry ; 30(24): e202304361, 2024 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-38284777

RESUMEN

Exchanging oxygen in the functional group C=O (i. e., carbonyl) for the less electronegative Group 16 elements, sulfur or selenium, unexpectedly enhances the electronegativity of the C=X group in π-conjugated molecules and reduces the molecular π HOMO-LUMO energy gap. Quantum-chemical analyses revealed that the steric size of the chalcogen atom X is at the origin of this seemingly counterintuitive behavior. This tuning of the chemical properties of carbonyl compounds by varying the chalcogen atom size in the C=X bond can be applied in many fields of chemistry. This concept article delineates several useful applications in the fields of organocatalysis, supramolecular chemistry, and photo(electro)chemistry.

7.
Chemistry ; 30(7): e202302933, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-37970753

RESUMEN

Telluronium salts [Ar2 MeTe]X were synthesized, and their Lewis acidic properties towards a number of Lewis bases were addressed in solution by physical and theoretical means. Structural X-ray diffraction analysis of 21 different salts revealed the electrophilicity of the Te centers in their interactions with anions. Telluroniums' propensity to form Lewis pairs was investigated with OPPh3 . Diffusion-ordered NMR spectroscopy suggested that telluroniums can bind up to three OPPh3 molecules. Isotherm titration calorimetry showed that the related heats of association in 1,2-dichloroethane depend on the electronic properties of the substituents of the aryl moiety and on the nature of the counterion. The enthalpies of first association of OPPh3 span -0.5 to -5 kcal mol-1 . Study of the affinity of telluroniums for OPPh3 by state-of-the-art DFT and ab-initio methods revealed the dominant Coulombic and dispersion interactions as well as an entropic effect favoring association in solution. Intermolecular orbital interactions between [Ar2 MeTe]+ cations and OPPh3 are deemed insufficient on their own to ensure the cohesion of [Ar2 MeTe ⋅ Bn ]+ complexes in solution (B=Lewis base). Comparison of Grimme's and Tkatchenko's DFT-D4/MBD-vdW thermodynamics of formation of higher [Ar2 MeTe ⋅ Bn ]+ complexes revealed significant molecular size-dependent divergence of the two methodologies, with MBD yielding better agreement with experiment.

8.
Chemistry ; 29(65): e202302332, 2023 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-37677126

RESUMEN

Frustrated Lewis pairs (FLPs) have been the subject of considerable study since the field's inception. While much of the research into FLPs has centered around small molecule activation for diverse stoichiometric and catalytic transformations, intramolecular FLPs also show promise as chelating ligands. The cooperative action of Lewis basic and acidic moieties enables intramolecular FLPs to stabilize low oxidation state centers and (consequently) reactive molecular fragments through a donor-acceptor approach, making them an attractive ligand class in main group element chemistry. This review outlines the state of FLP chelation to date throughout the p-block, encompassing primarily groups 13-16.

9.
Pharmaceuticals (Basel) ; 16(9)2023 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-37765124

RESUMEN

The antimicrobial properties of one of the most important secondary metabolites, Eugenol (EU), inspired us to design and synthesize three different series of derivatives enhancing its parent compound's anti-Helicobacter pylori activity. Thus, we prepared semisynthetic derivatives through (A) diazo aryl functionalization, (B) derivatization of the hydroxy group of EU, and (C) elongation of the allyl radical by incorporating a chalcogen atom. The antibacterial evaluation was performed on the reference NCTC 11637 strain and on three drug-resistant clinical isolates and the minimal inhibitory and bactericidal concentrations (MICs and MBCs) highlight the role of chalcogens in enhancing the antimicrobial activity (less than 4 µg/mL for some compounds) of the EU scaffold (32-64 µg/mL).

10.
Chemistry ; 29(50): e202301322, 2023 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-37317647

RESUMEN

Herein, a new tellurium and mercury containing mercuraazametallamacrocycle has been prepared via (2+2) condensation of bis(o-aminophenyl)telluride and bis(o-formylphenyl)mercury(II). The isolated bright yellow solid of mercuraazametallamacrocycle has adopted unsymmetrical figure-of-eight conformation in the crystal structure. To study the metallophilic interactions between closed shell metal ions, the macrocyclic ligand has been treated with two equiv. of AgOTf (OTf=trifluoromethansulfonate) and AgBF4 , which afforded greenish-yellow bimetallic silver complexes. The isolated silver complexes displayed intramolecular Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions as well as intermolecular Hg⋅⋅⋅Hg interactions and formed an extended 1D molecular chain by directing six atoms to interact as TeII ⋅⋅⋅AgI ⋅⋅⋅HgII ⋅⋅⋅HgII ⋅⋅⋅AgI ⋅⋅⋅TeII in a non linear fashion. The Hg⋅⋅⋅Ag, Te⋅⋅⋅Ag interactions have also been studied in solution by 199 Hg, 125 Te NMR spectroscopy, absorption, and emission spectroscopy. In DFT calculations, the Atom in Molecule (AIM) analysis, non-covalent interactions (NCI), natural bonding orbital (NBO) analysis strongly supported for experimental evidences and revealed that the intermolecular Hg⋅⋅⋅Hg interaction is stronger than the intramolecular Hg⋅⋅⋅Ag interactions.

11.
Chemistry ; 29(34): e202300850, 2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-36974900

RESUMEN

Our quantum chemical analyses elucidated how the replacement of O in the amide bonds of benzene-1,3-5-tricarboxamides (OBTAs) with the larger chalcogens S and Se enhances the intermolecular interactions and thereby the stability of the obtained hydrogen-bonded supramolecular polymers due to two unexpected reasons: i) the SBTA and SeBTA monomers have a better geometry for self-assembly and ii) induce stronger covalent (hydrogen-bond) interactions besides enhanced dispersion interactions. In addition, it is shown that the cooperativity in benzene-1,3,5-triamide (BTA) self-assembly is caused by charge separation in the σ-electronic system following the covalency in the hydrogen bonds.

12.
J Environ Manage ; 334: 117482, 2023 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-36801684

RESUMEN

Microbial transformations play a vital role in Se cycle in the environment and decrease the solubility and toxicity of Se oxyanions by converting to elemental selenium (Se0) nanostructures. Aerobic granular sludge (AGS) has attracted interest due to efficient reduction of selenite to biogenic Se0 (Bio-Se0) and retention in bioreactors. Here, selenite removal, biogenesis of Bio-Se0 and entrapment of Bio-Se0 by different size groups of aerobic granules were investigated to optimize biological treatment process for Se-laden wastewaters. Furthermore, a bacterial strain showing high selenite tolerance and reduction was isolated and characterized. Removal of selenite and conversion to Bio-Se0 were achieved by all the size groups of granules ranging from 0.12 mm to 2 mm and above. However, selenite reduction and Bio-Se0 formation were rapid and more efficient with large aerobic granules (≥0.5 mm). The formed Bio-Se0 was majorly associated with the large granules, due to better entrapment capabilities. In contrast, the Bio-Se0 formed by the small granules (≤0.2 mm) was distributed both in the granules and aqueous phase because of ineffective entrapment. Scanning electron microscope and energy dispersive X-ray (SEM-EDX) analysis confirmed formation of Se0 spheres and association with the granules. Efficient selenite reduction and entrapment of Bio-Se0 was related to prevalent anoxic/anaerobic zones in the large granules. A bacterial strain showing efficient SeO32- reduction of up to 15 mM SeO32- under aerobic conditions was identified as Microbacterium azadirachtae. SEM-EDX analysis confirmed the formation and entrapment of Se0 nanospheres (size: 100 ± 5 nm) in the extracellular matrix. The cells immobilized in alginate beads showed effective SeO32- reduction and Bio-Se0 entrapment. Efficient reduction and immobilization of bio-transformed metalloids by large AGS and AGS-borne bacteria implicates prospective use in bioremediation of metal(loid) oxyanions and bio-recovery.


Asunto(s)
Nanopartículas , Selenio , Selenio/química , Ácido Selenioso , Aguas del Alcantarillado , Nanopartículas/química , Biodegradación Ambiental , Bacterias
13.
Curr Med Chem ; 30(21): 2396-2420, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-35702779

RESUMEN

Sulfur and oxygen containing-compounds are a relevant class of derivatives that is constantly growing due to their wide range of pharmacological activity, including the antiviral one. As proof of this, there are several FDA approved antiviral compounds having sulfur and oxygen in their structures. Among RNA viruses, the flavivirus genus (e.g. Dengue, West Nile, Yellow Fever and Zika viruses) holds a relevant place within zoonotic pathogens and thus flavivirus infections are considered a growing risk for the public health. As a consequence, the drug discovery process aimed at identify new anti- flavivirus agents is of great relevance and will help to find effective therapies not available yet. One of the most alarming features of flaviviruses is their ability to co-infect the host, thus aggravating the symptoms of the disease. Therefore, finding compounds endowed with a broad-spectrum anti-flavivirus activity is now becoming a pressing need. In this review, we describe the most promising compounds having both sulfur and oxygen in their structures characterized by a broad-spectrum activity against different flaviviruses. Furthermore, the synthetic procedures applied for the preparation of the described derivatives are also reported. Readers can be inspired by the contents of this review to design and synthesize more effective anti-flavivirus agents as well as to select viral or host targets to achieve an antiviral activity as broadly as possible.


Asunto(s)
Infecciones por Flavivirus , Flavivirus , Infección por el Virus Zika , Virus Zika , Humanos , Flavivirus/genética , Oxígeno/uso terapéutico , Infecciones por Flavivirus/tratamiento farmacológico , Virus Zika/genética , Azufre/uso terapéutico , Antivirales/farmacología , Antivirales/uso terapéutico , Infección por el Virus Zika/tratamiento farmacológico
14.
Chemistry ; 29(7): e202202364, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36322693

RESUMEN

The separation of tellurium from cadmium telluride is examined using a unique combination of mild, anhydrous chlorination and complexation of the subsequent tellurium tetrachloride with 3,5-di-tert-butylcatecholate ligands (dtbc). The resulting tellurium complex, Te(dtbc)2 , is isolated in moderate yield and features a 103 to 104 reduction in cadmium content, as provided by XRF and ICP-MS analysis. Similar results were obtained from zinc telluride. A significant separation between Te, Se, and S was observed after treating a complex mixture of metal chalcogenides with this protocol. These three tunable steps can be applied for future applications of CdTe photovoltaic waste.

15.
Macromol Rapid Commun ; 44(4): e2200731, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36285613

RESUMEN

The synthesis and characterization of asymmetric alkoxy- are reported, fluoro-benzothiadiazole (BT) acceptor core derivatized with a series of six different heterocycles (selenophene, thiophene, furan, 5-thiazole, 2-thiazole and 2-oxazole). The effect of the flanked-heterocycles containing different chalcogen atoms of the six homopolymers (HPX) is studied using optical, thermal, electrochemical, and computational analysis. Computational calculations indicate a strong relationship between the most stable conformation for each homopolymer and their bearing heterocycle, thus homopolymers HPSe', HPTp', HPFu', and HPTzC5, adopted the syn-syn and syn-anti conformations due to their noncovalent interactions with shorter distances, while HPTzC2' and HPOx' demonstrate preference for the anti-anti conformation. Optical property studies of the homopolymers reveal a strong red-shift in solution and film upon exchanging the chalcogen atom from Oxygen < Sulfur < Selenium in HPFu, HPTp, and HPSe, respectively. In addition, deeper highest occupied molecular orbital (HOMO) energy levels are observed when the donor-acceptor moieties (HPSe, HPTp, and HPFu) are substituted for the acceptor-acceptor systems such as HPTzC5, HPTzC2, and HPOx. Improved packing and morphology are exhibited for the donor-acceptor homopolymers. Thus, having a flanked heterocycle containing different chalcogen-atoms in polymeric systems is one way of tuning the physicochemical properties of conjugated materials for optoelectronic applications.


Asunto(s)
Calcógenos , Tiadiazoles , Calcógenos/química , Oxígeno/química
16.
Materials (Basel) ; 15(24)2022 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-36556648

RESUMEN

Nanocrystals of Si doped with S, Se and Te were synthesized by annealing them in chalcogen vapors in a vacuum at a high temperature range from 800 to 850 °C. The influence of the dopant on the structure and morphology of the particles and their optical and electrical properties was studied. In the case of all three chalcogens, the recrystallization of Si was observed, and XRD peaks characteristic of noncubic Si phases were found by means of electronic diffraction for Si doped with S and Se. Moreover, in presence of S and Te, crystalline rods with six-sided and four-sided cross-sections, respectively, were formed, their length reaching hundreds of µm. Samples with sulfur and selenium showed high conductivity compared to the undoped material.

17.
ChemCatChem ; 14(17): e202200485, 2022 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-36245968

RESUMEN

Phenochalcogenazines such as phenoxazines and phenothiazines have been widely employed as photoredox catalysts (PCs) in small molecule and polymer synthesis. However, the effect of the chalcogenide in these catalysts has not been fully investigated. In this work, a series of four phenochalcogenazines is synthesized to understand how the chalcogenide impacts catalyst properties and performance. Increasing the size of the chalcogenide is found to distort the PC structure, ultimately impacting the properties of each PC. For example, larger chalcogenides destabilize the PC radical cation, possibly resulting in catalyst degradation. In addition, PCs with larger chalcogenides experience increased reorganization during electron transfer, leading to slower electron transfer. Ultimately, catalyst performance is evaluated in organocatalyzed atom transfer radical polymerization and a photooxidation reaction for C(sp2)-N coupling. Results from these experiments highlight that a balance of PC properties is most beneficial for catalysis, including a long-lived excited state, a stable radical cation, and a low reorganization energy.

18.
Angew Chem Int Ed Engl ; 61(41): e202207521, 2022 10 10.
Artículo en Inglés | MEDLINE | ID: mdl-35983584

RESUMEN

The deshielding or downfield 13 C NMR chemical shift of amide carbonyl carbon upon H-bonding is a widely observed phenomenon. This downfield shift is commonly used as a spectroscopic ruler for H-bonding. However, the very first observation of an upfield 13 C NMR of thiocarbonyl carbon in thioamides upon H-bonding encouraged us to explore the physical origin of the reversal of 13 C NMR chemical shielding. Careful NMR analysis shows that sulfur and selenium-centered H-bonds (S/SeCHBs) induce a shielding effect on the 13 CC=S(Se) while changing from amides to thioamides or selenoamides. In addition, natural chemical shielding (NCS) analysis shows that the σ11 and σ22 components of the isotropic shielding tensor (σ) have a crucial role in this unusual shielding.


Asunto(s)
Selenio , Carbono , Hidrógeno/química , Enlace de Hidrógeno , Azufre , Tioamidas
19.
Eur J Inorg Chem ; 2022(7): e202100934, 2022 Mar 09.
Artículo en Inglés | MEDLINE | ID: mdl-35873275

RESUMEN

The diorgano(bismuth)alcoholate [Bi((C6H4CH2)2S)OPh] (1-OPh) has been synthesized and fully characterized. Stoichiometric reactions, UV/Vis spectroscopy, and (TD-)DFT calculations suggest its susceptibility to homolytic and heterolytic Bi-O bond cleavage under given reaction conditions. Using the dehydrocoupling of silanes with either TEMPO or phenol as model reactions, the catalytic competency of 1-OPh has been investigated (TEMPO=(tetramethyl-piperidin-1-yl)-oxyl). Different reaction pathways can deliberately be addressed by applying photochemical or thermal reaction conditions and by choosing radical or closed-shell substrates (TEMPO vs. phenol). Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single-crystal X-ray diffraction analysis, and (TD)-DFT calculations.

20.
Angew Chem Int Ed Engl ; 61(36): e202206249, 2022 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-35797220

RESUMEN

The face-to-face association of (E)-1,2-di(4-pyridyl)ethylene (bpen) molecules into rectangular motifs stabilized for the first time by chalcogen bonding (ChB) interactions is shown to provide photoreactive systems leading to cyclobutane formation through single-crystal-to-single-crystal [2+2] photodimerizations. The chelating chalcogen bond donors are based on original aromatic, ortho-substituted bis(selenocyanato)benzene derivatives 1-3, prepared from ortho-diboronic acid bis(pinacol) ester precursors and SeO2 and malononitrile in 75-90 % yield. The very short intramolecular Se⋅⋅⋅Se distance in 1-3 (3.22-3.24 Å), a consequence of a strong intramolecular ChB interaction, expands to 3.52-3.54 Šin the chalcogen-bonded adducts with bpen, a distance (<4 Å) well adapted to the face-to-face association of the bpen molecules into the reactive position toward photochemical dimerization.

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