Total synthesis of Carpatamides A–D

A synthetic strategy was developed for the synthesis of the common core structure of Carpatamides A–D. The total synthesis of Carpatamides A and C was completed in 6 steps and of Carpatamides B and D in 7 steps, by employing the Wittig olefination, olefin cross metathesis and acid amine coupling reactions as key steps.     

Unified Asymmetric Total Syntheses of (−)-Alotaketals A–D and (−)-Phorbaketal A

The novel tricyclic spiroketal alotane-type sesterterpenoids showed strikingly different biological activities and potency with subtle structural alterations. Asymmetric total syntheses of the tricyclic sesterterpenoids (−)-alotaketals A–D and (−)-phorbaketal A were accomplished [29–31 steps from (−)-malic acid] in a collective way for the first time. The key features of the strategy included 1) a new cascade cyclization of vinyl epoxy δ-keto-alcohols to forge the common tricyclic spiroketal intermediate, 2) a late-stage allylic C−H oxidation, and 3) olefin cross-metathesis to install the different side chains.     

A straight forward and first total synthesis of Penilumamides B–D

A simple and straight forward first total synthesis of rare lumazine peptides, Penilumamide B, C and D isolated from the marine-derived fungi Aspergillus and Penicillium sp. is described from a common starting material, 1,3-dimethyllumazine-6-carboxylic acid. Penilumamide C was prepared from Penilumamide B by oxidation of the methionine residue to the corresponding sulphone.     

A new D–D–π–A dye for efficient dye-sensitized solar cells

New metal-free organic dye sensitizers containing mono-triphenylamine or bis-triphenylamine as the electron donor, a thiophene as the π-conjugated system, and a cyanoacrylic acid moiety as the electron acceptor were synthesized. The optical and electrochemical properties of the dyes were investigated,and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye containing bis-triphenylamine as the electron donor produced a photon-to-current conversion efficiency of 6.06%(Jsc = 14.21 m A/cm~2, Voc = 0.62 V, ff = 0.69) under 100 m W/cm~2 simulated AM 1.5 G solar irradiation(100 m W/cm~2).     

A series of novel 1D coordination polymers constructed from metal–quinolone complex fragments linked by aromatic dicarboxylate ligands

Self-assembly of quinolones with metal salts in the presence of aromatic dicarboxylate ligands affords a series of novel 1D metal–quinolone complexes, namely [Mn(Hppa)(oba)]·3H₂O (1), [Co(Hppa)(oba)]·3.25H₂O (2), [Zn(Hppa)(sdba)]·1.5H₂O (3), [Mn(Hcf)(bpda)(H₂O)]·2H₂O (4), [Mn(Hppa)₂(bpdc)] (5) and [Mn(Hlome)₂(bpdc)]·4H₂O (6) (Hppa = Pipemidic acid, Hcf = ciprofloxacin, Hlome = lomefloxacin). The structures of compounds 1–3 consist of novel polymeric chains spanning two different directions, which display an intriguing 1D → 3D inclined polycatenation of supramolecular ladders. Compound 4 exhibits a chain compound formed from the interconnection of [Mn₂(Hcf)₂(μ-CO₂)₂] dimers with bpda ligands. Compounds 5 and 6 are similar chain compounds constructed from [Mn(Hppa)₂] (or [Mn(Hlome)₂]) fragments linked by bpdc ligands. The magnetic properties of 4 have been studied, which indicate the existence of antiferromagnetic interactions. Furthermore, the luminescent properties of compound 3 are discussed.     

Heteroatom substitution-induced asymmetric A–D–A type non-fullerene acceptor for efficient organic solar cells

Research on asymmetric A–D–A structured non-fullerene acceptors has lagged far behind the development of symmetric counterpart. In this contribution, by simply replacing one sulfur atom in indacenodithiophene unit with a selenium atom, an asymmetric building block Se PT and a corresponding asymmetric non-fullerene acceptor Se PT-IN have been developed. Asymmetric Se PT-IN achieved a high efficiency of 10.20% in organic solar cells when blended with PBT1-C, much higher than that of symmetric TPT-IN counterpart(8.91%). Our results demonstrated an effective heteroatom substitution strategy to develop asymmetric A–D–A structured non-fullerene acceptors.     

Total synthesis of infectopyrone,aplysiopsenes A–C,ent-aplysiopsene D,phomapyrones A and D, 8,9-dehydroxylarone,and nectriapyrone

The total synthesis of the 2-pyrone natural products nectriapyrone, aplysiopsenes A–C, ent-aplysiopsene D, phomapyrones A and D, and of 8,9-dehydroxylarone were achieved by Wittig olefination starting with vermopyrone. Infectopyrone was synthesized by Horner–Wadsworth–Emmons reaction starting with phomapyrone D. Racemic phomapyrone C methyl ether was obtained by hydrogenation of nectriapyrone. The total syntheses were achieved starting from commercially available 3,5-heptanedione and led to the desired natural products in 18–46% over 5–6 steps, whereupon all five-step syntheses were carried out with a single chromatographic workup. The total synthesis of infectopyrone, aplysiopsenes A–D, of phomapyrones A and D, and of 8,9-dehydroxylarone were achieved for the first time, giving unambiguous proof for the proposed structures of these natural products.     

A phenyl imidazole dicarboxylate-based 3D terbium–organic framework for selective sensing of nitrobenzene

A novel lanthanide(III)–organic framework, {(Tb(μ₃-HPhIDC)(μ₂-C₂O₄)_0.5(H₂O))·2H₂O}_n (1) (H₃PhIDC = 2-phenyl-1H-imidazole-4,5-dicarboxylic acid) has been solvothermally synthesised and structurally characterised, which exhibits selective detection of nitrobenzene via a photoinduced electron transfer quenching mechanism. The high efficiency, stability and recyclability of 1 make it a potential chemosensor for nitrobenzene.     

1D Mn–Fe heterometallic coordination polymer built by an approach of metalloligand

1D heterometallic coordination polymer of [(Fe^II(L)₂)(Mn^III(salen))(ClO₄) · 2CH₃CN · CH₃OH] (1 · 2CH₃CN · CH₃OH) has been built through a metalloligand approach (L = hydrotris (1,2,4-triazolyl)borate). Ferrous [Fe^II(L)₂] moiety can be easily incorporated into further extended networks by the facile reduction of ferric antiprismatic [Fe^III(L)₂]⁺ metalloligand due to the reducing ability of borate ligands during the reaction. And more, hydroquinone facilitates the reduction. Therefore, we present single crystal X-ray structure analysis of 1 · 2CH₃CN · CH₃OH along with X-ray absorption spectroscopy to confirm the reduction of iron centres.     

Electronic and photophysical properties of the bend D–T–A–T–D derivatives for small-molecule organic photovoltaic (SM-OPV) solar cells: a DFT and TD-DFT investigation

A series of D–T–A–T–D derivatives (D, electron-donating moiety; T, π-conjugated linker; A, electron-acceptor moiety) with seven electron donor moieties and various electron abilities are designed to investigate the influence of the donor on photophysical properties for small-molecule organic photovoltaic solar cells. The 4,8-dimethoxybenzodithiophene (D₁), triphenyldsramine (D₂), 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline (D₃), 9,9-dimethyl-9H-fluorene (D₄), 9-methyl-9H-carbazole (D₅), 4-methyl-4H-dithieno-pyrrole (D₆), and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are adopted as the electron donor moiety. The BDTC (buta-1,3-diene-1,1,4,4-tetracarbonitrile) is used for the A moiety, and the thiophene (T) is used for the π-conjugated linker. The optimized structure of D–T–A–T–D derivatives exhibits the bend molecular conformation due to the steric effect within the A moiety. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of these derivatives are dependent on the electron donating ability of D, which influences the open-circuit voltage and driving force. Reorganization energy suggests that these derivatives are good hole-transporting type materials. Projected density of state analysis demonstrates that in the HOMO, the electron density distribution is delocalized on the terminal D and T moieties, while in the LUMO, the electron density distribution is localized mainly on the A moiety. The maximum absorption peak, which has relatively high light harvesting efficiency, is due to the π to π* transition and can be tuned by the electron-donating ability and the resonance energy of the D moiety. The bend D₆–T–A–T–D₆/D₇–T–A–T–D₇ derivatives with D moiety of 4-methyl-4H-dithieno-pyrrole (D₆) and 4,4-dimethyl-4H-cyclopenta-dithiophene (D₇) are good candidates as electron donor materials for SM-OPV.     

The Synthesis of a Multiple D–A Conjugated Macrocycle and Its Application in Organic Photovoltaic

As a novel class of materials, D–A conjugated macrocycles hold significant promise for chemical science. However, their potential in photovoltaic remains largely untapped due to the complexity of introducing multiple donor and acceptor moieties into the design and synthesis of cyclic π-conjugated molecules. Here, we report a multiple D–A ring-like conjugated molecule ( RCM ) via the coupling of dimer molecule DBTP-C3 as a template and thiophenes in high yields. RCM exhibits a narrow optical gap (1.33 eV) and excellent thermal stability, and shows a remarkable photoluminescence yield (Φ_PL) of 11.1 % in solution, much higher than non-cyclic analogues. Organic solar cell (OSC) constructed with RCM as electron acceptor shows efficient charge separation at donor-acceptor band offsets and achieves a power conversion efficiency (PCE) of 14.2 %-approximately fourfold higher than macrocycle-based OSCs reported so far. This is partly due to low non-radiative voltage loss down to 0.20 eV and a high electroluminescence yield (Φ_EL) of 4×10⁻⁴. Our findings emphasize the potential of D–A cyclic conjugated molecules in advancing organic photovoltaic technology.     

Mechanofluorochromism of carbazole-type D–π–A fluorescent dyes

We have newly designed and synthesized unsymmetrical carbazole-type D–π–A fluorescent dyes. The dyes show a bathochromic shift-type mechanofluorochromism (MFC): grinding of as-recrystallized dyes induces a bathochromic shift of fluorescent color and the fluorescent color is recovered by heating or exposure to solvent vapor. In order to clarify the MFC mechanism for the carbazole-type D–π–A fluorescent dyes, time-resolved fluorescence spectroscopy, X-ray powder diffractometry, single-crystal X-ray structural analysis, IR spectroscopy, and differential scanning calorimetry are performed before and after grinding of the solids. On the basis of experimental results and semi-empirical molecular orbital calculations (AM1 and INDO/S), we have revealed that the MFC is attributed to a reversible switching between crystalline and amorphous states with changes of intermolecular hydrogen bonding and π–π interaction.     

Photodissociation dynamics of D2O via the B̃(1A1) electronic state

Photodissociation dynamics of D(2)O in the B?((1)A(1)) state at different photolysis wavelengths have been investigated using the D-atom Rydberg "tagging" time-of-flight (TOF) technique, in combination with a tunable vacuum ultraviolet photolysis light source. TOF spectra of the D-atom product from the D(2)O photodissociation in both parallel and perpendicular polarizations have been measured. Product kinetic energy distributions and angular distributions have been derived from these TOF spectra. From these distributions, internal state distributions of the OD product as well as the OD quantum state specific angular anisotropy parameters have been derived. Two product channels governed by distinct dissociation dynamics have been clearly observed in the B?((1)A(1)) state photodissociation: ground electronic state radical product OD(X (2)Π) + D and excited electronic state OD(A (2)Σ(+)) + D. The OD(A) + D channel proceeds via adiabatic pathway on the B?((1)A(1)) state surface, producing rovibrational excitation in the OD(A) product, while the OD(X) + D channel is generated through nonadiabatic pathway mainly via conical intersections between the B?((1)A(1)) and the X?((1)A(1)) state surfaces. Due to strong angular force induced by the conical intersections, the OD(X) product is extremely hot in the rotational excitation close to the energy limit (N ～ 50 for v = 0). However, the vibrational excitation is cold in the OD(X) product with dominant population in the ground vibrational state v = 0. Detailed experimental results at different photolysis wavelengths show that at higher energy the unstable periodic orbit, from which dissociation starts, on the B? state has stronger excitation degree of the OD internal state. The negative angular anisotropy parameters of the OD(A) products suggest that the angular forces in this adiabatic dissociation pathway from these periodic orbits have changed the original angular distribution of the D(2)O molecule excited by the B?((1)A(1))←X?((1)A(1)) parallel transition.     

Electrochemical and Opto-Electronic Properties of Carbazole-Based Derivatives with Symmetric A–CZ–A Architecture

In this work novel bisheterocyclic derivatives of alkylcarbazole with A–CZ–A architecture are investigated (CZ stands for alkylcarbazole). The study presents their opto-electronic and electrochemical properties which influence on the possibility of their prospective application. Monomers undergo electropolymerisation with formation of conducting layer of polythiophene derivatives, while presence of chalcone moiety hampers the process. Two-step oxidation processes of polymers results in generation of polaron and bipolaron types of charge carriers on the macromoleculs’ chains. The charge is delocalized over center and side subunits (bithiophene or bithiazole one) in first stage of oxidation. It is possible to influence on the properties of the polymers and their composition by variation of synthesis condition like solvent polarity and applied potential boundaries. Obtained conducting polymers show high stability under ambient conditions. Their energy gap values are estimated with electrochemical and spectroscopic methods.     

Toonapolyynes A–D,new polyynes from Toona ciliata

Abstract

Phytochemical investigation on the leaves and twigs of Toona ciliata has led to the isolation of four new polyynes (1–4) and two knowns (5 and 6). Their structures were determined by extensive spectroscopic analysis (MS, UV, IR, and NMR) and Mosher’s method. All compounds were evaluated for their inhibitory activities against HepG2 human tumor cell line but were inactive.     

Concise total syntheses of Marinoquinolines A–C

The first concise total syntheses of pyrroloquinoline natural products, Marinoquinolines A–C, have been achieved in six linear steps from commercially available starting materials. The key steps were a reaction between (p-tolylsulfonyl)methylisocyanide (TosMIC) and α, β-unsaturated ester under basic condition to prepare the pyrrole moiety and Morgen-Walls reaction to construct quinoline ring.     

A New Method for the Synthesis of C/D Ring Synthon of Vitamin D

Inrecentyears,vitaminDresearchareahasbeenstimulatedbythediscoveriesthatIQ,25-dihydroxyvitaminD,,theactivemetaboliteofvitaminD,,inadditiontotheclassicalrolesofregulatingcalciumandphosphorusmetabolisms',hasamuchbroaderspectrumofactivitiesthanoriginallythought,suchaspromotingcelldifferelltiationandinhibitingcellproliferation"'.Thebiologicalsignificanceandmedicalneedshaveledeffortstowardthesearchforanaloguesofpotentcelldifferelltiationandantiproliferationactivitywithouttoxichypercalcemiaassociate…     

Improved Synthesis of (–)-Agelastatin A

Optimization of key steps in the synthesis of the architecturally unique tetracyclic antitumor alkaloid (–)-agelastatin A (1) improved the overall yield of the 11-step process (eight operations) from 9% to 23%. Changing the solvent and using a more efficient N-benzyl deprotecting-group procedure enhanced the yields of the C-ring and D-ring intermediates, (–)-4 and (–)-7, respectively. Bromination of (–)-7 with 1,3-dibromo-5,5-dimethylhydantoin, rather than N-bromosuccinimide (NBS), increased the yield of (–)-1 from 69% to more than 94% yield.     

A study of the extraction of plutonium from planchets by Aridus–ICP–SFMS

Two extraction processes of plutonium (Pu) on planchets from alpha spectrometry (AS) have been evaluated by inductively coupled plasma sector field mass spectrometry with a desolvator system (Aridus–ICP–SFMS). The samples were traced with known concentrations of ²³⁹Pu (1.2 × 10³ fg) and ²⁴²Pu (2 × 10³ fg) followed by an electrodeposition in planchets, according to the Hallstadius method. The processes of extraction were carried out with 50 mL of 0.36 mol L^?1 HNO₃ every 30 min up to 180 min in a glass beaker at 60 °C. The first process was on a hotplate and the second used an ultrasonic system. Finally, samples were evaporated to dryness, and resuspended in 10 mL of 0.72 mol L^?1 HNO₃ for evaluation. The results showed that at 120 min, a ~70 % recovery of ²³⁹Pu and a ~80 % recovery of ²⁴²Pu in both processes were obtained. The average recoveries of ²³⁹Pu and ²⁴²Pu at 180 min using the hotplate in plate were 93.4 ± 4.6 and 93.7 ± 4.2 % respectively, and with the ultrasonic system were 96.0 ± 4.3 and 98.2 ± 1.0 % respectively. In conclusion, both processes are suitable for Pu extraction, and Aridus–ICP–SFMS is an essential technique for the reassessments and quantification of Pu. In addition, procedural blanks spiked with 1 × 10² fg mL^?1 U were prepared for each process, in order to study the contribution of the ²³⁸U on the background signal at m/z = 239, which was 0.5 ± 0.2 cps, indicating that the contribution of ²³⁸U on the ²³⁹Pu signal was negligible. Furthermore, this methodology can be applied to sample planchets with environmental, food, biological and nuclear origin, and thereby to avoid repetitive analysis when Pu concentration determined by AS are under minimum detectable activities.     

Assembly of Organic–Inorganic Hybrids From 1D to 2D Framework Based on Triethanolamine-Functionalized Molybdovanadate with Electrochemical Sensing of Ascorbic Acid

Journal of Cluster Science - Two new organic–inorganic hybrids, (TeaH)2[Cu(Tea)(H2O)2]2[Cu(Tea)]2[HN(CH2CH2O)3VMo6O22]2·12H2O (1),...