ABSTRACT New derivatives of spiroisoxazolines were synthesized via a 1, 3‐dipolar cycloaddition reaction between various nitrile oxides and 9α‐hydroxy‐1β,10α‐epoxyparthenolide. The natural epoxide precursor, 9α‐hydroxy‐1β,10α‐epoxyparthenolide, was obtained through the stereoselective epoxidation of the natural product 9α‐hydroxyparthenolide, which was isolated in grams from the aerial parts of Anvillea radiata . This approach underscores the versatility of natural product derivatives in constructing novel heterocyclic compounds with potential biological activity. The structures of all products have been characterized by 1 H NMR, 1 3 C{ 1 H} NMR spectral analysis, and high‐resolution mass spectrometry (HRMS). Notably, the molecular structure of compound 5e was unambiguously established by single‐crystal x‐ray diffraction analysis, providing detailed insight into its stereochemistry and solid‐state conformation. Furthermore, density functional theory (DFT) calculations were employed to investigate the chemical reactivity of the 1,3‐dipolar cycloaddition between compound 2 and nitrile oxide 3a , and the results confirmed the experimental findings.

With the purpose of exploring alternatives to the poorly stable astatoaryl bond found in most 211At-labeled radiopharmaceuticals, the coordination between astatine and metal-NHC (NHC = N-heterocyclic carbene) complexes was investigated. To orient this work, relativistic DFT calculations were performed, highlighting a superiority of gold(I) over rhodium(I) and iridium(I), both regarding the strength of the metal-astatine bond and the metal's preference for astatine over other halogens. The DFT calculations also revealed a more stable metal-astatine bond with electron-withdrawing NHCs. Accordingly, two Au(I) complexes, [AuCl(IPr)] (IPr = N,N'-bis[2,6-(di-isopropyl)phenyl]imidazol-2-ylidene) and [AuCl(IAd)] (IAd = N,N'-bis[adamantyl]imidazol-2-ylidene) were radiolabeled by halide exchange in excellent radiochemical yields with iodine-125 and astatine-211 in a water/acetonitrile mixture with a reducing agent. While the adamantyl-substituted complex was not investigated further due to its lack of solubility in aqueous or semi aqueous media, the stability of [Au211At(IPr)] in the presence of phosphate-buffered saline was evaluated and proved excellent (96% after two half-lives), encouraging further studies with relevant cancer-targeting vectors.

An electron-deficient tetranitroazacalixarene is shown to undergo reversible cyanide capture via nucleophilic aromatic substitution, yielding an unprecedented class of metastable dianionic macrocycle incorporating two Meisenheimer units, fully characterized by single-crystal X-ray diffraction, NMR, and electronic absorption spectroscopies. Acting as a chemical fuel, cyanide transiently drives the formation of this adduct, which can spontaneously regenerate the parent macrocycle under mild conditions, representing a rare demonstration of metastability in a Meisenheimer complex. The dynamic behavior of this system, reminiscent of out-of-equilibrium assemblies, is finely tunable through macrocycle concentration, counterion nature, solvent, and temperature. Detailed crystallographic, spectroscopic, and computational analyses reveal that intramolecular hydrogen bonding plays a key role in stabilizing the adduct. Comparative studies with simpler analogues further highlight the importance of macrocyclic preorganization and non-covalent interactions in governing this reversible reactivity.

The quinolone scaffold is a key structural motif found in heterocycles exhibiting biological activities, coordination behaviors, and photosensitizing properties. Herein, we report the synthesis and photophysical characterization of Donor-π-Acceptor (D-π-A) systems incorporating the pyrroloquinolone core. By varying the electron-donating and electron-withdrawing substituents, we demonstrate the formation of charge-transfer (CT) fluorophores exhibiting Stokes shifts exceeding 6000 cm-1 and red emission. While the absorption spectra are essentially unaffected by solvent polarity, pronounced positive solvatofluorochromism is observed. Fluorescence quenching is nevertheless noted in polar solvents such as acetone, acetonitrile, and ethanol. The photophysical behavior of the dyes is further rationalized through time-dependent density functional theory (TD-DFT) calculations.

This study presents the synthesis and the characterization of a new covalent zinc porphyrin‐fullerene (ZnP‐C 60 ) dyad, featuring a π‐conjugated bridge to link the donor (ZnP) and the acceptor (C 60 ). This system, along with a couple more reference compounds, namely ZnP‐3DoH‐COOH and C 60 tr ZnPCOOH , is tested as photosensitizers in p ‐type dye‐sensitized solar cells ( p ‐DSSCs). Photophysical studies, including absorption and emission spectroscopy, reveal strong electronic communication between the porphyrin core and the fullerene unit, corroborated by theoretical calculations demonstrating efficient electron transfer from the donor to the acceptor. Electrochemical measurements, supported by theoretical insights, confirm that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital(LUMO) energy levels of the C 60 ‐3PV‐ZnP‐2DoH‐COOH dyad are well aligned for effective integration into NiO‐based DSSCs. Notably, photovoltaic performance measurements show that solar cells sensitized with the covalent dyad exhibit significantly enhanced efficiencies compared with those using the reference compounds and other “ZnP‐Acceptor” dyads. These findings highlight the potential of covalent ZnPor‐C 60 assemblies in advancing the design of high‐performance p ‐type DSSCs.

This article describes a synthesis of epoxy dienone products starting from para-substituted phenols bearing an electron-deficient alkene at the meta position. This one-pot photooxygenation/epoxidation transformation takes place at room temperature using catalytic amounts of Rose Bengal and cesium carbonate upon green light irradiation. This reaction provides access to a range of functionalized epoxy dienone products with diastereoisomeric ratios ranging from 4:1 to > 12:1. DFT calculations and mechanistic experiments revealed that this reaction would proceed through singlet oxygen-mediated photooxidation of phenols followed by an intramolecular oxygen atom transfer on the alkene side arm.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

We report the design, synthesis, and characterization of two new carbazole-based organic dyes PC1-2 as potential sensitizers for NiO-based p-type dye-sensitized solar cells (p-DSSCs). The D-A-pi-A' configured PC1 dye comprises a thienyl unit as a pi-spacer and a malononitrile as an end-capping acceptor unit, whereas in PC2(,) the cyanovinylene group serves as an acceptor unit and a thienyl group acts as a donor unit in a D-A-D configuration. These molecules achieved excellent solubility due to their long-branched alkyl chains. The current work encompasses their structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies, establishing structure-property relationships. PC1-2 exhibit lambda(abs) and lambda(emi) in the range of 389-404 and 448-515 nm, respectively, with a band gap in the range of 2.88-2.92 eV. Electrochemical studies confirm the feasibility of electron injection, regeneration, and recombination. The introduction of an additional electron-withdrawing group (cyanovinylene group) on the dye PC1 skeleton endows it with a higher dye loading capacity, high hole injection, and a strengthened intramolecular charge transfer (ICT) effect, resulting in a redshifted ICT absorption with a higher molar extinction coefficient. Among the two new dyes, the device based on PC1 achieved the highest power conversion efficiency (PCE) of 0.027% with a short-circuit current density (J(SC)) of 1.29 mAmiddotcm(-2), open-circuit voltage (V-OC) of 67 mV, and fill factor (FF) of 31%, whereas the device with dye PC2 performed less efficiently (PCE: 0.018%, J(SC): 0.92 mAmiddotcm(-2), V-OC: 68 mV, and FF: 30%). Conclusively, the study provides insights into the intricacies involved in the structural modification of carbazole-based p-type dyads for the development of highly efficient DSSCs.

Finding new efficient p-type sensitizers for NiO photocathodes is a great challenge for the development of promising low-cost tandem dye-sensitized solar cells (DSSCs). Now, the focus of researchers investigating these cells has been to create high-performance p-type systems. With this intention, herein, the design and synthesis of six new phenoxazine-based donor-acceptor (D-A)-configured organic dyes PO1-6 was reported, comprising different acceptor moieties specially designed for the sensitization of mesoporous p-type semiconductor NiO for the construction of p-type DSSCs (p-DSSCs). This work includes structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies of these dyes, including evaluation of their structure-property relationships. The optical studies revealed that PO1-6 displayed adequate absorption and emission features in the range of 480-550 and 560-650 nm, respectively, with a bandgap in the order of 2.05-2.40 eV, and their thermodynamic parameters favored an efficient interfacial charge transfer involving NiO. Among the six new dyes, the device based on sensitizer PO2 carrying electron-withdrawing 1,3-diethyl-2-thiobarbituric acid achieved the highest power conversion efficiency of 0.031 % (short-circuit current density=0.89 mA cm(-2), open-circuit voltage=101 mV, and fill factor=35 %). Conclusively, the study furnishes an understanding of the intricacies involved in the structural modification of phenoxazine-based sensitizers to further ameliorate the performance of the p-type DSSCs.

A variety of physicochemical properties and several hydrogen-bond donors have been used to define methods and to build scales aiming at measuring the hydrogen-bond acceptance of solvents. There is a great deal of confusion in these scales and methods. Solvatochromic, solvatocalorimetric, solvatovibrational, and 19F solvatomagnetic comparison methods are critically reviewed. Only two methods, the solvatomagnetic and the solvatocalorimetric ones, are able to yield reliable solvent hydrogen-bond acceptance scales. The solvatomagnetic β1 scale defined from the 19F chemical shift of 4-fluorophenol is extended to many solvents including ionic liquids and green solvents. The results for about 240 hydrogen-bond acceptor solvents are organized in a numerical β1 database. The comparison of β1 with solvatochromic scales highlights their shortcomings, in particular for the important class of amphiprotic solvents. Therefore, the use of the 19F solvatomagnetic comparison method and of the solvatomagnetic β1 scale is recommended in solvent effect studies.

Green plasmon excitation of colloidal Au nanoparticles, onto which a copper( ii ) complex was grafted, in the presence of nitrobenzaldehyde and nitromethane in DMF, lead to the formation of the corresponding nitroaldol with high efficiency.

The discovery of a multiple-bond-forming process merging the singlet oxygen-mediated dearomatization of 3,4-disubstitued phenols and diastereo- and regioselective epoxidation is described. This one-pot strategy using a transition metal-free multicatalytic system comprised of rose bengal and cesium carbonate allowed the efficient formation of functionalized epoxyquinol products under mild conditions. Mechanistic investigations have been performed to shed the light on the key species involved in this transformation.

Exploring a catalytic reaction other than water oxidation at the photoanode of a photoelectrochemical cell is probably a key feature to more efficiently generate the electrons needed to produce solar fuels. In this framework, we describe herein the fabrication of a TiO2-based dye-sensitized photo-electrosynthesis cell (DSPEC) using a zinc porphyrin (ZnP) sensitizer and a 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) organo-catalyst that quite efficiently catalyzes light-driven oxidation of methoxybenzyl alcohol into aldehyde. Two dyads ZnP-TEMPO, differing by the anchoring group (carboxylic acid and hydroxamic acid) on ZnP, were prepared and their electrochemical, absorption, and emission properties were recorded and quantum chemical modeling was realized. The photovoltaic performances in dye-sensitized solar cells were first examined in order to optimize the dyeing conditions and compare the relative efficiencies of the compounds. The dyads substituted with TEMPO outperform the reference zinc porphyrin lacking TEMPO with a much higher J(sc) and V-oc. The photocatalytic properties after immobilization on TiO2 nanocrystalline films toward para-methoxy benzyl alcohol oxidation were explored in borate buffer and in an acetonitrile electrolyte. In borate buffer, the optimal pH was 8 and using dyad ZnP-TEMPO anchored with hydroxamic acid, para-methoxy benzaldehyde was selectively produced with an average photocurrent density of 200 mu A/cm(2), a Faradaic efficiency of 82%, a turnover number (TON) of 26, and a turnover frequency (TOF) of 47 h(-1). In acetonitrile, in the presence of 0.1 M N-methyl-imidazole, the same dyad gives an average photocurrent density of about 100 mu A/cm(2), a Faradaic efficiency of 76%, a TON of 13, and a TOF of 24 h(-1). The stability of the anchor is crucial in the acetonitrile electrolyte, where the dyad is quite soluble since only the dyad functionalized with hydroxamic acid is compatible with these organic solvent conditions. Overall, this study paves the way to the development of more efficient and probably more stable TiO2-based DSPECs for alcohol oxidation that could advantageously complement those devoted to water oxidation.

In this study, we report the utilization of BODIPY-(Zn)Porphyrin hybrids in photocatalytic H-2 production from water. These entities were applied as photosensitizers upon their chemisorption onto the surface of platinum-doped titanium dioxide nanoparticles (Pt-TiO2), which acted as photocatalysts. To evaluate the impact of the different connectivity between the chromophores in photocatalytic in H-2 evolution, we employed two diverse BODIPY-(Zn)Porphyrin entities, in which the BODIPY moiety is either covalently attached (BDP-Por) or axially coordinated (BDP(Im)-Por) with the (Zn)Porphyrin. The covalently connected dyad (BDP-Por) presented higher catalytic activity (17 500 TONs) compared to the axial coordinated (BDP(Im)-Por, 13 700 TONs). In BDP-Por dyad, an additional BDP(Im) moiety was introduced and the formed hybrid (BDP-Por-BDP(Im)) outperformed the aforementioned systems, due to the enhanced light harvesting ability. Overall, we developed highly efficient dye-sensitized photocatalytic systems (DSPs) based on noble-metal-free photosensitizers reaching 18 600 turnover numbers (TONs) and 225 mmol(H-2) g(cat)(-1) h(-1).

In the current work, we present the use of two free-base and two zinc-metallated porphyrin-ruthenium(II) polypyridine dyads, along with two reference porphyrin derivatives, as sensitizers in both n- and p-type DSSCs and DSPECs. Two of the dyads contain the well-known Ru(bpy)3 unit (HOOC-DMP-Ru(bpy)3 and HOOC-(Zn)DMP-Ru(bpy)3), while in the other two terpyridine-Ru(Cl)-bypiridine was used (HOOC-DMP-tpy-Ru and HOOC-(Zn)DMP-tpy-Ru). In all systems, the amide-bonding motif was utilized for the connection of the counterparts comprising each dyad. Photophysical investigation of the reported systems indicated sufficient electronic interactions for the dyads in their excited states (emission measurements). The photovoltaic measurements revealed that the presence of the ruthenium complex improves the overall performance of the dyads with the most efficient dyad being HOOC-(Zn)DMP-tpy-Ru in both n- and p-type DSSCs. Consequently, HOOC-(Zn)DMP-tpy-Ru was used to fabricate n- and p-DSPECs towards the oxidation of methoxy-benzyl alcohol and the reduction of CO2, respectively.

A highly enantioselective synthesis of (R,S) or (S,S)-2,6-disubstituted dehydropiperidines has been previously achieved through Sn/Li transmetalation of the corresponding stannylated dehydropiperidines or of their precursors. Herein, we successively consider their Upjohn's syn dihydroxylation and their anti-dihydroxylation via an epoxidation reaction followed by epoxide opening reaction. The stereochemical course of these reactions was first reported including the use of appropriate protecting groups before considering the conversion of the obtained compounds into NH or NMe iminosugar hydrochlorides. A primary evaluation of the designed iminosugar C-glycosides as glycosidase inhibitors suggests candidates for the selective inhibition of α-galactosidase, amyloglycosidase and naringinase. Beyond the reported results, the method constitutes a highly modulable route for the synthesis of well stereodefined iminosugar C-glycosides, an advantage which might be used for the design of iminosugars to enhance their biological properties.

We identified a new series of azole antifungal agents bearing a pyrrolotriazinone scaffold. These compounds exhibited a broad in vitro antifungal activity against pathogenic Candida spp. (fluconazole-susceptible and fluconazole-resistant) and were 10- to 100-fold more active than voriconazole against two Candida albicans isolates with known mechanisms of azole resistance (overexpression of efflux pumps and/or specific point substitutions in the Erg11p/CYP51 enzyme). Our lead compound 12 also displayed promising in vitro antifungal activity against some filamentous fungi such as Aspergillus fumigatus and the zygomycetes Rhizopus oryzae and Mucor circinelloides and an in vivo efficiency against two murine models of lethal systemic infections caused by Candida albicans.

The anchoring group of a sensitizer may strongly affect the overall properties and stability of the resulting dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrosynthetic solar cells (DSPECs). The properties of seven perylene monoimide (PMI) dyes have been comprehensively studied for their immobilization on nanocrystalline NiO film. The PMI dyes differ only by the nature of the anchoring group, which are: carboxylic acid (PMI-CO2H), phosphonic acid (PMI-PO3H2), acetyl acetone (PMI-acac), pyridine (PMI-Py), aniline (PMI-NH2), hydroxyquinoline (PMI-HQ), and dipicolinic acid (PMI-DPA). The dyes are investigated by cyclic voltammetry and spectroelectrochemistry and modeled by TD-DFT quantum chemical calculations. The mode of binding of these anchoring groups is investigated by infrared spectroscopy and the stability of the binding to NiO surface is studied by desorption experiments in acidic and basic media. The phosphonic acid group is found to offer the strongest binding to the NiO surface in terms of stability and dye loading. Finally, a photophysical study by ultrafast transient absorption spectroscopy shows that all dyes inject a hole in NiO with rate constants on a subpicosecond timescale and display similar charge recombination kinetics. The photovoltaic properties of the dyes show that PMI-HQ and PMI-acac give the highest photovoltaic performances, owing to a lower degree of aggregation on the surface.

Mono- and di-anchoring gamma-pyranylidene-based organic dyes featuring D-pi-A and D-(pi-A)(2) architectures have been engineered as sensitizers for applications in Dye-Sensitized Solar Cells (DSSCs). Their photophysical, electrochemical and photovoltaic properties were further investigated. TD-DFT calculations were performed to rationalize the trends observed in the optical and electrochemical properties of the dyes. The investigation of the photovoltaic performances of this series of new dyes provided structure-property relationships where their Power Conversion Efficiencies (PCE) could be correlated to structural features, such as the length of the pi-conjugated spacer, the nature of the substituents on the pyranylidene electron donor moiety and the number of anchoring groups. Dye-Sensitized Solar Cells based on mono-anchoring dyes were more efficient than the corresponding cells based on di-anchoring analogues due to high dye loading. The highest Power Conversion Efficiency of 5.23% was achieved with the mono-anchoring 17a dye containing t-butyl substituent groups on the pyranylidene fragment and with one thienyl pi-conjugated spacer.