Heterobasidion annosum s.s. and H. parviporum are severe pathogens of conifers causing butt rot and root rot thus reducing the economic value of timber. Here, the antifungal activity of Bacillus subtilis isolate A18 against these two Heterobasidion species was investigated. Five different culture media with different culture age were investigated to study the effect of substrate composition and culture age for metabolite production. Bacterial cultures and cell-free culture filtrates were tested for antifungal activity. Inhibition of fungal growth was analysed using the agar disc-diffusion method. MALDI-TOF and LC-HRMS analyses were used to identify the antifungal metabolites. Substrate composition and age of culture were found to be active variables with direct effect on the antifungal activity of bacterial culture extracts. High anti-fungal activity was observed when B. subtilis was cultured in PDB, SGB and LB media for four days. Mass-spectrometry analysis showed the presence of lipopeptides in culture filtrates identified as members of the surfactins, polymixins, kurstakins and fengycins. A culture filtrate containing fengycin-type lipopeptides showed the highest bioactivity against Heterobasidion species. Bacterial cultures had higher bioactivity compared to their respective cell free culture filtrates. The results of the present study suggest that B. subtilis A18 is a powerful biocontrol agent against Heterobasidion infections of tree wounds and stumps.

The combination of anline and tetrafluoroboric acid diethyl etherate (2.5 mol% and 5 mol%, respectively) significantly accelerates the formation of sulfinyl imines in dichloromethane and isopropylacetate at room temperature compared to previous procedures. A DFT and NMR spectroscopic study shows that the anilinium tetrafluoroborate complex is solvated by sulfinamide molecules in the initial state and that the rate-limiting step of the reaction is the addition of the sulfinamide molecule to the protonated aniline-based imine. In addition, the catalytic system was also utilised in a one-pot, two step reaction, where the in situ formed sulfinyl imine was arylated in a rhodium catalysed reaction with high diastereoselectivity.

The development of facilely synthesized, dopant-free hole-transporting materials (HTMs) with high efficiency is of great significance for the potential application of perovskite solar cells (PSCs). Herein, we report two novel indolo[3,2-b]carbazole (ICZ) based small molecules obtained via a three-step reaction in a high yield without using expensive catalysts, namely C201 and C202, and further apply them as dopant-free HTMs in PSCs. Compared with C201, C202 contains two additional biphenylamino groups to improve its spatial configuration. It is found that the interplay between the molecular geometry and the aggregation behavior can exert a great influence on the film formation property and thus on the device performance. Strikingly, the champion devices employing C202 as the HTM deliver a much higher PCE of up to 17.7%, which is substantially higher than that of devices containing C201 (8.7%) under 100 mW cm(-2) illumination (AM 1.5G). It is revealed that the C202 capping layer exhibits a more homogeneous and uniform surface morphology as compared to that of C201, which effectively reduces the charge recombination losses and facilitates charge extraction, leading to a much-enhanced photovoltaic performance. This is the first example of ICZ core-based small molecules as dopant-free HTMs in PSCs. Moreover, the PSCs containing C202 as the HTM also exhibited good long-term stability under ambient conditions (40% RH) as compared to devices with doped spiro-OMeTAD, due largely to the hydrophobic nature of C202 which prevented moisture from destroying the perovskite film. This work offers a new avenue for developing cost-effective and stable HTMs for PSCs and other optoelectronic devices.

Modulation of ion-transfer processes across nanometer-sized voltammetry membranes by ferrocene-based self-assembled monolayer on regular glassy carbon electrode is herein demonstrated. The composition of the membrane is advantageously tuned to promote either cation or anion transfer: the presence of an exchangeable cation results in cation transfer, whereas a lipophilic salt induces anion transfer through the fulfilment of the electroneutrality of the system. When an anodic scan oxidizes ferrocene moieties in the monolayer, these are stabilized by the pairing of lipophilic anions present in the membrane. As a result, either, hydrophilic cations present in the membrane are expelled into the solution or anions enter from the solution generating hence reversible and voltammetric waves for these transfers. The use of a redox active monolayer rather than a conducting polymer film or a redox active compound into the membrane overcomes a number of drawbacks previously manifested by these systems. The confinement of the redox process in a thin film at the immediate vicinity of the membrane allows to avoid the need of elevated number of redox moieties to be sued in the membrane, therefore suppressing its acute leaching and being compatible with the incorporation of both cation and anion ionophores for the first time. In this sense, assisted transfer of lithium and chloride are shown as proof-of-concept. Here, the peak potential of the associated voltammetric waves shifts according to the Nernst equation, in analogy to potentiometric sensors. Analytical detection of lithium and chloride ions in real samples is additionally presented.

Emissions of defence chemicals from Norway spruce seedlings can be induced by feeding arthropods or by exogenous hormonal application. Some defence chemicals may attract or repel associated arthropods. The aim of this study was to show that it is possible to detect and collect stress-induced volatiles from micro sites, such as at the scale of a single needle, in vivo by using SPME. Methyl jasmonate application on the stem of Norway spruce seedlings induced emission of (E)-beta-farnesene only from the needles closest to the application site. Emissions of (E)-beta-farnesene, (E,E)-alpha-farnesene and (E)-alpha-bisabolene were only detected from needles infested by the spider mite Oligonychus ununguis. The total volatile amount detected by SPME-GC-MS reached a considerable mass of 14 ng/needle/24 h, suggesting that emission from damaged and stressed conifers might have a larger impact on the macro climate than previously estimated.

Earth-abundant transition-metal-based oxides are potential candidates to replace the state-of-the-art noble-metal-based oxygen evolution catalysts (OECs) such as IrO2 and RuO2. Despite the low cost and large abundance, copper-based OER catalysts have been less frequently studied, mainly owing to the low electrical conductivity of copper oxides that results in large overpotential and sluggish kinetics for oxygen evolution. We report here the insitu fabrication of semi-metallic Cu3P nanorod arrays on commercial copper foam via a template approach; the resulting self-supported core-shell Cu-Cu3P/CuO electrode has the merits of high electrical conductivity, large active area, and short diffusion paths for electrolyte and evolved oxygen, exhibiting a low overpotential of 315mV and high durability over 50h at a current density of 10mAcm(-2) for OER in 1.0 M KOH. The remarkable OER performance reported here is not only superior to that of analogous Cu-CuO foam electrode, but also outperforms those of copper-based OER electrocatalysts in the literature.

Essential oils extracted from the leaves of Libyan Rosemary (Rosmarinus officinalis L.), and Miswak (Salvadora persica L.) were evaluated for their acaricidal and repellent effects on Ixodes ricinus L. nymphs (Acari: Ixodidae) using a bioassay based on an open filter paper method'. Rosmarinus officinalis leaf essential oil diluted to 0.5 and 1 mu l/cm(2) in acetone exhibited, respectively, 20 and 100% tick mortality after about 5h of exposure. A total of 50 and 95% of I. ricinus nymphs were killed by direct contact with the oil when exposed to lethal concentrations (LC)of 0.7 mu l/cm(2) (LC50) and 0.95 mu l/cm(2) (LC95), respectively. The LC50 (0.5 mu l/cm(2)) was reached before the end of the first 24h of exposure time (ET), as tick mortality at 24h was 60%. Salvadora persica leaf essential oil at 1 mu l/cm(2) showed a significant repellency effect against I. ricinus nymphs at 1.5h ET. A 95% repellency was observed at a repellent concentration (RC95) of 1 mu l/cm(2) of S. persica, but no significant mortality was recorded at this dose of S. persica oil. Gas chromatography-mass spectrometry analyses showed that the main monoterpenes in both oils were 1,8-cineol, -pinene, and -pinene, although in markedly different proportions. These results suggest that essential oils have substantial potential as alternative approaches for I. ricinus tick control.

Co-sensitization of molecular dyes and catalysts on semiconductor surfaces is a promising strategy to build photoelectrodes for solar fuel production. In such a photoelectrode, understanding the charge transfer reactions between the molecular dye, catalyst and semiconductor material is key to guide further improvement of their photocatalytic performance. Herein, femtosecond mid-infrared transient absorption spectroscopy is used, for the first time, to probe charge transfer reactions leading to catalyst reduction on co-sensitized nickel oxide (NiO) photocathodes. The NiO films were co-sensitized with a molecular dye and a proton reducing catalyst from the family of [FeFe](bdt)(CO)(6) (bdt = benzene-1,2-dithiolate) complexes. Two dyes were used: an organic push-pull dye denoted E2 with a triarylamine-oligothiophene-dicyanovinyl structure and a coumarin 343 dye. Upon photo-excitation of the dye, a clear spectroscopic signature of the reduced catalyst is observed a few picoseconds after excitation in all co-sensitized NiO films. However, kinetic analysis of the transient absorption signals of the dye and reduced catalyst reveal important mechanistic differences in the first reduction of the catalyst depending on the co-sensitized molecular dye (E2 or C343). While catalyst reduction is preceded by hole injection in NiO in C343-sensitized NiO films, the singly reduced catalyst is formed by direct electron transfer from the excited dye E2* to the catalyst in E2-sensitized NiO films. This change in mechanism also impacts the lifetime of the reduced catalyst, which is only ca. 50 ps in E2-sensitized NiO films but is >5 ns in C343-sensitized NiO films. Finally, the implication of this mechanistic study for the development of better co-sensitized photocathodes is discussed.

A facile preparation of bio-inspired and morphology controllable catalytic electrode FeS@MoS2/CFC, featuring a carbon fiber cloth (CFC) covered with FeS dotted MoS2 nanosheets, has been established. Synergy between the CFC as a self-standing conductive substrate and the FeS nanoparticle dotted MoS2 nanosheets with abundant active sites makes the noble-metal-free catalytic electrode FeS@MoS2/CFC highly efficient in nitrogen reduction reaction (NRR), with an ammonia production rate of 8.45 mu g h(-1) cm(-2) and excellent long-term stability at -0.5 V in pH neutral electrolyte. Further electrolysis in acidic and alkaline electrolytes revealed the overall NRR catalytic activity of this electrode over a wide pH range.

Production cost per peak watt of solar electricity produced is critical to various PV technologies and second-generation thin-film solar cells. The dye-sensitized solar cell (DSC), a molecular solar cell technology, has the potential to significantly lower production costs below previous PV technologies. DSC research groups have been established around the world. Integration into different products opens up new commercial opportunities for niche applications with large flexibilities in product shape, color, and transparency. 

The regioselective organocatalytic ring-opening polymerization (ROP) of a 6-membered cyclic carbonate, rac-1-methyl trimethylene carbonate, was studied using phosphazene base (t-BuP2) as the principle catalyst. The influence on the reaction kinetics caused by the reaction temperature (-74-60 degrees C), catalyst loading (0.5-2.5%), and reaction solvent (toluene and tetrahydrofuran) was systematically tuned and followed by H-1 NMR. All studied reactions reached close to or above 90% monomer conversion in 3 h, and all exhibited typical equilibrium polymerization behavior that is inherent to 6-membered cyclic carbonates. Good control over the molecular weight and distribution of the polycarbonate product was obtained in most studied conditions, with M-n ranging from similar to 4k to similar to 20k and D < 1.2. The regioregularity (X-reg) of the resulting polycarbonate was thoroughly studied using various NMR techniques, with the highest X-reg obtained being.0.90. The major influence from the reaction conditions on both the ROP kinetics and X-reg are as follows: higher reaction temperature resulted in a decrease of both; higher catalyst loading resulted in a faster ROP reaction but a slight decrease in X-reg; and toluene being a better solvent resulted in both faster reaction and higher X-reg. Throughout this study, we have demonstrated the possibility to synthesize regioregular aliphatic polycarbonate using an organic base as the ROP catalyst, contrary to the existing studies on similar systems where only metal-base catalysts were in focus and our systems showed similar high X-reg of the product.

A bifunctional amine/squaramide catalyst promoted direct aldol addition of an hydantoin surrogate to pyridine 2-carbaldehyde N-oxides to afford adducts bearing two vicinal tertiary/quaternary carbons in high diastereo- and enantioselectivity (d.r. up to >20:1; ee up to 98 %) is reported. Acid hydrolysis of adducts followed by reduction of the N-oxide group yields enantiopure carbinol-tethered quaternary hydantoin-azaarene conjugates with densely functionalized skeletons. DFT studies of the potential energy surface (B3LYP/6-31+G(d)+CPCM (dichloromethane)) of the reaction correlate the activity of different catalysts and support an intramolecular hydrogen-bond-assisted activation of the squaramide moiety in the transition state of the catalytic reaction.

Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole-transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low-cost and excellent stability. However, the most efficient PSCs using CuPc-based HTMs reported thus far still rely on hygroscopic p-type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc-Bu and CuPc-OBu, by molecular engineering of the non-peripheral substituents of the Pc rings, and applied as dopant-free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant-free CuPc-OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc-Bu (14.3%). Moreover, PSCs containing dopant-free CuPc-OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro-OMeTAD. This work thus provides a fundamental strategy for the future design of cost-effective and stable HTMs for PSCs and other optoelectronic devices.

Conventional methods for carrying out carbon-hydrogen functionalization and carbon-nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon-carbon and carbon-heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

Lignocellulosic biomass is available in large quantities and constitutes an attractive feedstock for the sustainable production of bulk and fine chemicals. Although methods have been established for the conversion of its cellulosic fractions, valorization of lignin has proven to be challenging. The difficulty in disassembling lignin originates from its heterogeneous structure and its propensity to undergo skeletal rearrangements and condensation reactions during biorefinery fractionation or biomass pretreatment processes. A strategy for hindering the generation of these resistive interunit linkages during biomass pretreatment has now been devised using formaldehyde as a stabilizing agent. The developed method when combined with Ru/C‐catalyzed hydrogenolysis allows for efficient disassembly of all three biomass fractions: (cellulose, hemicellulose, and lignin) and suggests that lignin upgrading can be integrated into prevailing biorefinery schemes.

During the past decade, visible light photocatalysis has become a powerful synthetic platform for promoting challenging bond constructions under mild reaction conditions. These photocatalytic systems rely on harnessing visible light energy for synthetic purposes through the generation of reactive but controllable free radical species. Recent progress in the area of visible light photocatalysis has established it as an enabling catalytic strategy for the mild and selective generation of nitrogen-centered radicals. The application of visible light for photocatalytic activation of amides, hydrazones, and imides represents a valuable approach for facilitating the formation of nitrogen-centered radicals. Within the span of only a couple of years, significant progress has been made for expediting the generation of amidyl, hydrazonyl, and imidyl radicals from a variety of precursors. This Perspective highlights the recent advances in visible light-mediated generation of these radicals. A particular emphasis is placed on the unique ability of visible light photocatalysis in accessing elusive reaction manifolds for the construction of diversely functionalized nitrogen-containing motifs and as a platform for nontraditional bond disconnections in contemporary synthetic chemistry.

The laboratory of Professor Corey Stephenson at the University of Michigan (Ann Arbor, USA) has had an interest in lignin depolymerization since 2014. According to Corey Stephenson there were two main reasons that initially attracted their attention towards lignin. On the one hand, there is its abundance and unique aromatic backbone, which makes it an exceptional renewable source for small aromatic chemicals. On the other hand there are only few examples of selective methodologies found in the literature regarding its depolymerization, a majority of them employing harsh conditions due to its recalcitrant nature. He added: “Since the major interest of my laboratory focuses on harnessing the energy of visible light, we saw the opportunity of using photoredox catalysis to selectively cleave the ß-O–4 bonds present in the lignin backbone, a methodology that proved to be exceptionally robust for lignin model systems.

However, a prior oxidation step was required to achieve this fragmentation, which prompted us to search for alternative oxidation methodologies.” Such a method is presented in the present ACS Central Science publication.”

Lignin valorization has long been recognized as a sustainable solution for the renewable production of aromatic compounds. Two-step oxidation/reduction strategies, whereby the first oxidation step is required to “activate” lignin systems for controlled fragmentation reactions, have recently emerged as viable routes toward this goal. Herein we describe a catalytic protocol for oxidation of lignin model systems by combining photoredox and Pd catalysis. The developed dual catalytic protocol allowed the efficient oxidation of lignin model substrates at room temperature to afford the oxidized products in good to excellent yields.

Catalysts for oxidation of water to molecular oxygen are essential in solar-driven water splitting. In order to develop more efficient catalysts for this oxidatively demanding reaction, it is vital to have mechanistic insight in order to understand how the catalysts operate. Herein, we report the mechanistic details associated with the two Ru catalysts 1 and 2. Insight into the mechanistic landscape of water oxidation catalyzed by the two single-site Ru catalysts was revealed by the use of a combination of experimental techniques and quantum chemical calculations. On the basis of the obtained results, detailed mechanisms for oxidation of water by complexes 1 and 2 are proposed. Although the two complexes are structurally related, two deviating mechanistic scenarios are proposed with metal-ligand cooperation being an important feature in both processes. The proposed mechanistic platforms provide insight for the activation of water or related small molecules through nontraditional and previously unexplored routes.

The use of photochemical transformations is a powerful strategy that allows for the formation of a high degree of molecular complexity from relatively simple building blocks in a single step. A central feature of all light-promoted transformations is the involvement of electronically excited states, generated upon absorption of photons. This produces transient reactive intermediates and significantly alters the reactivity of a chemical compound. The input of energy provided by light thus offers a means to produce strained and unique target compounds that cannot be assembled using thermal protocols. This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds. Synthetic designs based on photochemical transformations have the potential to afford complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.

The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)(2)](Cl)(2) but instead to [Cu(dmp)(2)Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu-(dmp)(2)Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E-1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)(2)](+), as one may expect. Instead, [Cu(dmp)(2)](+) is isolated as a product when the reduction of [Cu(dmp)(2)Cl]PF6 is performed with L-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)(2)](2+) complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)(2)](ClO4)(2) crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)(2)(CH3CN)](ClO4)(2), in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)(2)(CH3CN)](2+) is identical to the one of [Cu(dmp)(2)](+), if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.

Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)(2)](+), [Cu(dmp)(2)](+), [Cu(Br-dmp)(2)](+), [Cu(bcp)(2)](+), [Cu(dsbtmp)(2)](+), [Cu(biq)(2)](+), and [Cu(dap)(2)](+) in solution, and those of their heteroleptics [Cu(dbda)(dmp)](+), [Cu(dbda)(Br-dmp)](+), [Cu(dbda)(bcp)](+), [Cu(dbda)(dsbtmp))(+), [Cu(dbda)(biq)](+), [Cu(dbda)(dap)](+) adsorbed on the surface of anatase TiO2 (dbda = 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid; dmp = 2,9-dimethyl-1,10-phenanthroline; Br-dmp = 5-bromo 2,9-dimethyl-1,10-phenanthroline; bcp = bathocuproine or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline; biq = 2,2'-biquinoline; dap = 2,9-dianisyl-1,10-phenanthroline). We show that the maximum absorption wavelengths of the heteroleptic complexes on TiO2 can be reasonably predicted from those of the homoleptic complexes in solution through a simple linear relation, whereas the prediction of their redox properties is less trivial. In the latter case, two different linear patterns emerge: one including the ligands bcp, biq, and dap and another one including the ligands dmp, Br-dmp, and dsbtmp. We offer an interpretation of the data based on the chemical structure of the ligands. On one hand, ligands bcp, biq, and dap possess a more extended pi-conjugated system, which gives a more prominent contribution to the overall redox properties of the ligand dbda. On the other hand, the ligands dmp, Br-dmp, and dsbtmp are all phenanthroline-based containing alkyl substituents and contribute less than dbda to the overall redox properties.

Binuclear ruthenium complexes bearing the 2,2'-bipyridine-6,6'-dicarboxylate (bda) ligand have been demonstrated to be highly active catalysts towards water oxidation with CeIV as an oxidant. However, the catalytic properties of ruthenium dimers have not yet been explored for visible light-driven water oxidation. Herein, the photocatalytic performance of a dipyridyl propane-bridged ruthenium dimer 2 was investigated in comparison with its monomeric precursor, [Ru(bda)(pic)2] (1), in CH3CN/phosphate buffer mixed solvent in a three-component system including a photosensitizer and a sacrificial electron acceptor. Experimental results showed that the activity of each catalyst was strongly dependent on the content of CH3CN in the phosphate buffer, which not only affected the driving force for water oxidation, but also altered the kinetics of the reaction, probably through different mechanisms associated with the O–O bond formation. As a result, dimer 2 showed significantly higher activity than monomer 1 in the solvent containing a low content of CH3CN, and comparable activities were attained with a high content of CH3CN in the solvent. Under the optimal conditions, complex 2 achieved a turnover number of 638 for photocatalytic O2 evolution.

Transparent wood is a candidate for use as an energy-saving building material due to its low density (ca. 1.2 g/cm(3)), high optical transmittance (over 85% at 1 mm thickness), low thermal conductivity (0.23 W m(-1) K-1), and good load-bearing performance with tough failure behavior (no shattering). High optical transmittance also makes transparent wood a candidate for optoelectronic devices. In this work, for the first time, perovskite solar cells processed at low temperature (<150 degrees C) were successfully assembled directly on transparent wood substrates. A power conversion efficiency up to 16.8% was obtained. The technologies demonstrated may pave the way for integration of solar cells with light transmitting wood building structures for energy-saving purposes.

A silver-mediated reaction between 2-ethynyl-3-(1-hydroxyprop-2-yn-1-yl)phenols or 2-ethyn-yl-3-(1-hydroxy-prop-2-yn-1-yl)anilines and methylene isocyanides has been developed. A sequential 5-endo-dig cyclization and [3 + 2] cycloaddition process is proposed. This synthetic strategy is atom- and step-efficient and applicable to a broad scope of substrates, allowing the synthesis of valuable substituted benzofuran- and indole-pyrroles in moderate to high yields.

The selective modification of alpha-amino acids and peptides constitutes a pivotal arena for accessing new peptide-based materials and therapeutics. In recent years, visible light photoredox catalysis has appeared as a powerful platform for the activation of small molecules via single-electron transfer events, allowing previously inaccessible reaction pathways to be explored. This review outlines the recent advances, mechanistic underpinnings, and opportunities of applying photoredox catalysis to the expansion of the synthetic repertoire for the modification of specific amino acid residues. 1 Introduction 2 Visible-Light-Mediated Functionalization of alpha-Amino Acids 2.1 Decarboxylative Functionalization Involving Redox-Active Esters 2.2 Direct Decarboxylative Coupling Strategies 2.3 Hypervalent Iodine Reagents 2.4 Dual Photoredox and Transition-Metal Catalysis 2.5 Amination and Deamination Strategies 3 Photoinduced Peptide Diversification 3.1 Gese-Type Bioconjugation Methods 3.2 Peptide Macrocyclization through Photoredox Catalysis 3.3 Biomolecule Conjugation through Arylation 3.4 C-H Functionalization Manifolds 4 Conclusions and Outlook

A silver-induced cycloaddition of isocyanides with acyl chlorides has been developed. This transition metal-catalyzed strategy provides an effective and scalable approach for the formation of 2,5-disubstituted oxazoles in good to high yields. The employed silver-based MOF catalyst can be efficiently recycled without compromising the yield.

A novel blue-colored organic donor-pi-acceptor sensitizer, the so-called MKA16 dye, has been employed to construct solid-state dye-sensitized solar cells (ssDSSCs). Using 2,2',7-,7'-tetrakis(N,N-di-p-methoxyphenyl-amine) 9,9'-spirobifuorene (Spiro-OMeTAD) as hole-transport material, a good conversion efficiency of 5.8% was recorded for cells based on the MKA16 dye and a high photovoltage of 840 mV in comparison with 5.6% efficiency using the known (Dyenamo Blue) dye. By co-sensitization using the orange-colored D35 dye and MKA16 together, the solid-state solar cells showed an excellent efficiency of 7.5%, with a high photocurrent of 12.41 mA cm(-2) and open-circuit voltage of 850 mV. The results show that the photocurrent of ssDSSCs can be significantly improved by co-sensitization mainly attributed to the wider light absorption range contributing to the photocurrent. In addition, results from photo-induced absorption spectroscopy show that the dye regeneration is efficient in co-sensitized solar cells. The current results possible routes of improving the design of aesthetic and highly efficient ssDSSCs.

An efficient and robust water oxidation catalyst based on abundant and cheap materials is the key to converting solar energy into fuels through artificial photosynthesis for the future of humans. The development of molecular water oxidation catalysts (MWOCs) is a smart way to achieve promising catalytic activity, thanks to the clear structures and catalytic mechanisms of molecular catalysts. Efficient MWOCs based on noble-metal complexes, for example, ruthenium and iridium, have been well developed over the last 30 years; however, the development of earth-abundant metal-based MWOCs is very limited and still challenging. Herein, the promising prospect of iron-based MWOCs is highlighted, with a comprehensive summary of previously reported studies and future research focus in this area.

Resistance to herbivores and pathogens is considered a key plant trait with strong adaptive value in trees, usually involving high concentrations of a diverse array of plant secondary metabolites (PSM). Intraspecific genetic variation and plasticity of PSM are widely known. However, their ecology and evolution are unclear, and even the implication of PSM as traits that provide direct effective resistance against herbivores is currently questioned. We used control and methyl jasmonate (MJ) induced clonal copies of genotypes within families from ten populations of the main distribution range of maritime pine to exhaustively characterize the constitutive and induced profile and concentration of PSM in the stem phloem, and to measure insect herbivory damage as a proxy of resistance. Then, we explored whether genetic variation in resistance to herbivory may be predicted by the constitutive concentration of PSM, and the role of its inducibility to predict the increase in resistance once the plant is induced. We found large and structured genetic variation among populations but not between families within populations in resistance to herbivory. The MJ-induction treatment strongly increased resistance to the weevil in the species, and the genetic variation in the inducibility of resistance was significantly structured among populations, with greater inducibility in the Atlantic populations. Genetic variation in resistance was largely explained by the multivariate concentration and profile of PSM at the genotypic level, rather than by bivariate correlations with individual PSM, after accounting for genetic relatedness among genotypes. While the constitutive concentration of the PSM blend did not show a clear pattern of resistance to herbivory, specific changes in the chemical profile and the increase in concentration of the PSM blend after MJ induction were related to increased resistance. To date, this is the first example of a comprehensive and rigorous approach in which inducibility of PSM in trees and its implication in resistance was analyzed excluding spurious associations due to genetic relatedness, often overlooked in intraspecific studies. Here we provide evidences that multivariate analyses of PSM, rather than bivariate correlations, provide more realistic information about the potentially causal relationships between PSM and resistance to herbivory in pine trees.

A scalable homogeneous metal-catalyzed protocol for direct amidation of carboxylic acids is presented. The use of 2-10 mol% of the commercially available Zr(Cp)(2)(OTf)(2)center dot THF results in high yields of amides at moderate temperature, using an operationally convenient reaction protocol that circumvents the use of water scavenging techniques.

Interspecific phenotypic variation in plant secondary metabolites (PSM) is often explained by biotic and abiotic factors. However, patterns of variation within species do not clearly fit the theoretical predictions. Exploring how genetics, environment and demographic processes shape such variation among and within populations is crucial for understanding evolution of PSM, particularly in long-lived plants such as forest trees. Here, we quantified genetic variation in PSM among and within populations, and explored drivers of local adaptation by studying the role of climate as a source of population differentiation in PSM of maritime pine. Constitutive profile and concentrations of 63 PSM and their herbivory-associated inducibility were determined in the bark of 130 clonally replicated genotypes with known familial structure from 10 populations covering the distribution range of the species. We compared neutral and quantitative population genetic differentiation of PSM (F ST and Q ST ). Also, we accounted for population genetic structure and kinship among individuals when exploring climate–trait relationships. We found large population differentiation and additive genetic variation in constitutive PSM. Many PSM were inducible, although very low genetic variation was observed with respect to their inducibility. Q ST –F ST comparisons suggest that differentiation of most diterpenes, monoterpenes, and phenolics can be explained by neutral demographic processes. Spatially heterogeneous selection across populations leading to local adaptation was only found for total constitutive sesquiterpenes and a few individual PSM. After accounting for population genetic structure, only the constitutive concentration of two sesquiterpenes showing signs of diversifying selection was predicted by climate, with decreasing concentrations along a growth-prone climatic gradient. Synthesis. Evolutionary patterns of plant secondary metabolites depended on their chemical nature, with neutral differentiation governing most plant secondary metabolites. Evidence of local adaptation was only found for total constitutive sesquiterpenes and a few individual plant secondary metabolites. The low genetic variation in the inducibility of plant secondary metabolites suggests a conserved model of defensive induction in this species. Since population differentiation linked to past demographic history could lead to false positives of adaptive differentiation signals, accounting for the genetic relatedness among populations is required to infer the environmental determinants of intraspecific genetic variation in putatively adaptive traits such as plant defences.

Lignin, which is a highly cross-linked and irregular biopolymer, is nature's most abundant source of aromatic compounds and constitutes an attractive renewable resource for the production of aromatic commodity chemicals. Herein, we demonstrate a practical and operationally simple two-step degradation approach involving Pd-catalyzed aerobic oxidation and visible-light photoredox-catalyzed reductive fragmentation for the chemoselective cleavage of the beta-O-4 linkage-the predominant linkage in lignin for the generation of lower-molecular-weight aromatic building blocks. The developed strategy affords the beta-O-4 bond cleaved products with high chemoselectivity and in high yields, is amenable to continuous flow processing, operates at ambient temperature and pressure, and is moisture- and oxygen-tolerant.

A comprehensive molecular analysis of a simple aqueous complexing system. U(VI) acetate. selected to be independently investigated by various spectroscopic (vibrational, luminescence, X-ray absorption, and nuclear magnetic resonance spectroscopy) and quantum chemical methods was achieved by an international round-robin test (RRT). Twenty laboratories from six different countries with a focus on actinide or geochemical research participated and contributed to this scientific endeavor. The outcomes of this RRT were considered on two levels of complexity: first, within each technical discipline, conformities as well as discrepancies of the results and their sources were evaluated. The raw data from the different experimental approaches were found to be generally consistent. In particular, for complex setups such as accelerator-based X-ray absorption spectroscopy, the agreement between the raw data was high. By contrast, luminescence spectroscopic data turned out to be strongly related to the chosen acquisition parameters. Second, the potentials and limitations of coupling various spectroscopic and theoretical approaches for the comprehensive study of actinide molecular complexes were assessed. Previous spectroscopic data from the literature were revised and the benchmark data on the U(VI) acetate system provided an unambiguous molecular interpretation based on the correlation of spectroscopic and theoretical results. The multimethodologic approach and the conclusions drawn address not only important aspects of actinide spectroscopy but particularly general aspects of modern molecular analytical chemistry.

The most common view of carbocations in organic chemistry is that they are short-lived intermediates in several fundamental reactions, e.g. the classic SN1-reaction. However, carbocations that can delocalize their positive charge can be stable enough to be isolated and used as Lewis acid catalysts, phase transfer catalysts or oxidants in various reactions. The theme of this thesis concerns applying trityl cations as Lewis acid catalysts in different organic reactions. The first chapter presents a general introduction of the field of Lewis acids, the characteristics and applications of carbocations in different organic reactions, and the aims of this thesis. The second chapter describes the carbocation-catalyzed asymmetric Diels–Alder reactions assisted by chiral counteranions. The third chapter shows that carbocations can be utilized as catalysts in oxa-Diels–Alder reactions with unactivated aldehydes and dienes as substrates. The fourth chapter investigates the application of carbocation catalysis in bromination reactions for selective functionalization at the benzylic position and on the aromatic ring, respectively. The fifth chapter highlights that carbocation-catalyzed aldehyde–olefin metathesis reactions can be achieved in high yields by suppressing the decomposition of both starting materials and products.

The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst isdemonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction wasconducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadingsdown to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable toan extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to mostpreviously reported strategies, this protocol does not require any radical initiator or extensive heating. Forelectron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3CH functionalization and arene sp2 CH functionalization by simply alternating the solvent. Thischemoselective switch allows for high substrate control and easy preparation of benzyl bromides andbromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 CBr and sp2 CBr functionality.

A highly efficient aldehyde-olefin metathesis catalysed by the carbocation, 4-phenylphenyl-diphenylmethylium ion, has been developed. This protocol is characterized by high yields, low catalyst loading (down to 2 mol%), good functional group compatibility and mild reaction conditions.

A highly efficient aldehyde-olefin metathesis catalyzed by the carbocation, 4-phenylphenyl-diphenylmethylium ion has been developed. This protocol is characterized by high yields, low catalyst loading (down to 2 mol%), good functional group compatibility and mild reaction conditions.

Singlet fission directly from the upper excited vibrational and electronic states of cofacial perylene dimers, bypassing the relaxed state S-1, was detected within 50 fs. This process competes well with vibrational cooling in S-1 (4.7-7.0 ps) and S-2 -> S-1 internal conversion (380 fs). The singlet fission has the energy threshold E = 3.06 eV. Other competitive relaxation processes are excimer and dimer cation formation on an ultrafast time scale. Excitation to higher energy levels (4.96 eV) leads to a higher efficiency of singlet fission.

The development of an efficient, stable, and low-cost hole-transporting material (HTM) is of great significance for perovskite solar cells (PSCs) from future commercialization point of view. Herein, we specifically synthesize a dicationic salt of X60 termed X60(TFSI)(2), and adopt it as an effective and stable "doping" agent to replace the previously used lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) for the low-cost organic HTM X60 in PSCs. The incorporation of this dicationic salt significantly increases the hole conductivity of X60 by two orders of magnitude from 10(-6) to 10(-4) S cm(-1). The dramatic enhancement of the conductivity leads to an impressive power conversion efficiency (PCE) of 19.0% measured at 1 sun illumination (100 mW cm(-2), AM 1.5 G), which is comparable to that of the device doped with LiTFSI (19.3%) under an identical condition. More strikingly, by replacing LiTFSI, the PSC devices incorporating X60(TFSI)(2) also show an excellent long-term durability under ambient atmosphere for 30 days, mainly due to the hydrophobic nature of the X60(TFSI)(2) doped HTM layer, which can effectively prevent the moisture destroying the perovskite layer. The present work paves the way for the development of highly efficient, stable, and low-cost HTM for potential commercialization of PSCs.

Living matter is built on complex dynamic systems consisting of numerus biotransformations. By exploiting the adaptive and evolutive behaviors ofmolecular matter, dynamic chemistry has developed as an important tool tounderstand the organization of nonliving matter into complex living systems.This thesis concerns three aspects of dynamic chemistry with a general focus onthe influence of different stimuli on the structures and functions of dynamicsystems.The first section focuses on dynamic kinetic resolution, where enzymes areutilized for asymmetric synthesis of an enantiopure (2R,5R)-1,3-oxathiolane. Byemploying surfactant-treated subtilisin Carlsberg and Candida antarcticalipase B, the absolute configuration of the resulting 1,3-oxathiolane ring couldbe efficiently controlled.The second section addresses the motional dynamics of configurational enamineswitch systems controlled by multiple stimuli. Complete forward and backwardrotation around the enamine C=C bond could be precisely regulated uponaddition of acid/base or metal ions. The enamine switches exhibited specificsensing ability for CuII ions in solution. Moreover, the enamines exhibitedswitchable aggregation-induced emission in the solid state, which could beapplied in the development of sensors as well as fluorescent organogel.Lastly, the enamine switches could readily undergo constitutional exchange withprimary amines under catalytic acidic conditions, resulting in dynamic enaminesystems. However, under basic conditions or in the presence of excessive acid,this process exhibited extremely slow kinetics, leading to an efficient regulationof the exchange process by controlling the switch status with regulation of pHin the system.

An enantiopure (2R,5R)-1,3-oxathiolane derivative was obtained using amultienzymatic cascade protocol. By employing a combination of surfactant-treatedsubtilisin Carlsberg and Candida antarctica lipase B, the absolute configuration of theresulting 1,3-oxathiolane ring was efficiently controlled, resulting in an excellentenantiomeric excess (> 99%). This enantiopure 1,3-oxathiolane derivative is a keyprecursor to anti-HIV agents, such as lamivudine, through subsequent N-glycosylation.

An enantiopure (2R,5R)-1,3-oxathiolane was obtained using a multienzymatic cascade protocol. By employing a combination of surfactant-treated subtilisin Carlsberg and Candida antarctica lipase B, the absolute configuration of the resulting 1,3-oxathiolane ring was efficiently controlled, resulting in an excellent enantiomeric excess (>99%). This enantiopure 1,3-oxathiolane derivative is a key precursor to anti-HIV agents, such as lamivudine, through subsequent N-glycosylation.

Dual configurational and constitutional dynamics in systems based on enamine molecularswitches has been systematically studied. pH-responsive moieties, such as 2-pyridyl and 2-quinolinyl units, were required on the “stator” part, also providing enamine stability throughintramolecular hydrogen-bonding (IMHB) effects. Upon protonation or deprotonation, forward andbackward switching could be rapidly achieved. Extension of the stator π-system in the 2-quinolinylderivative provided a higher E-isomeric equilibrium ratio under neutral conditions, pointing to ameans to achieve quantitative forward/backward isomerization processes. The ‘rotor’ part of theenamine switches exhibited constitutional exchange ability with primary amines. Interestingly,considerably higher exchange rates were observed with amines containing ester groups, indicatingpotential stabilization of the transition state trough IMHB. Acids, particularly BiIII, were found toefficiently catalyze the constitutional dynamic processes. In contrast, the enamine and the formeddynamic enamine system showed excellent stability under basic conditions. This coupledconfigurational and constitutional dynamics expand the scope of dynamic C-C and C-N bonds, andpotentiates further studies and applications in the fields of molecular machinery and systemschemistry.

A family of responsive enaminitrile molecular switches showing tunable turn-onfluorescence upon switching and aggregation is reported. Activated by addition of acid/base,isomerization around the C=C bond could be effectuated, resulting in complete, reversible switchingto the E- or Z-isomers. Typical aggregation-induced emission could be recorded for one specificstate of the different switches. By subtle tailoring of the parent structure, a series of compounds withemission covering almost the full visible color range were obtained. The switchable AIE features ofthe enaminitrile structures enabled their demonstration as solid state chemosensors to detect acidicand basic vapors, where the emission displayed an “off-on-off” effect. X-ray crystal analysis andDFT calculations suggested a restriction of intramolecular rotation mechanism, and anintramolecular charge transfer effect in the AIE luminogens.

Multistimuli-responsive enaminitrile-based configurational switches displaying aggregation-induced emission (AIE), fluorescence turn-on effects, and supergelation properties are presented. The E-isomers dominated (>97%) in neutral/basic solution, and the structures underwent precisely controlled switching around the enamine C═C bond upon addition of acid/base. Specific fluorescence output was observed in response to different external input in the solution and solid states. In response to H+, configurational switching resulted in complete formation of the nonemissive Z-H+-isomers in solution, however displaying deep-blue to blue fluorescence (ΦF up to 0.41) in the solid state. In response to CuII in the solution state, the E-isomers exhibited intense, turn-on, blue-green fluorescence, which could be turned off by addition of competitive coordination. The acid/base-activated switching, together with the induced AIE-effects, further enabled the accomplishment of a responsive superorganogelator. In nonpolar solvents, a blue-fluorescent supramolecular gel was formed upon addition of acid to the E-isomer suspension. The gelation could be reversed by addition of base, and the overall, reversible process could be repeated at least five cycles.