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Hydrogen from water splitting presents a sustainable energy solution with high energy density. Semiconductor photocatalysts facilitate this process but face challenges such as sluggish kinetics and selectivity. Zinc Cadmium Sulfide (ZnxCd1-xS) has emerged as a promising photocatalyst due to its tunable band gap and strong visible light absorption. Despite its potential, ZnxCd1-xS photocatalysts often suffer from rapid charge carrier recombination, particle agglomeration, and limited absorption. This review systematically examines ZnxCd1-xS photocatalysts, focusing on synthesis, characterization, and modification strategies including cocatalyst loading, heterojunction formation, and morphology engineering. It critically evaluates the photocatalytic performance of these materials in seawater and wastewater, highlighting the challenges and proposing future research directions to enhance their practical application.

Two-step thermochemical H2S splitting process is a promising method to recover both H2and S from a toxic waste H2S gas via low/high metal sulfide conversion. Several studies have examined the potential of the process experimentally. Still, there is a lack of comprehensive research into such as to provide a guideline for selecting the appropriate metal for the process. The most common metals in the periodic Table (28 metals) have been examined to find stable low/high metal sulfide couples. A list consisting of 17 metals that can form thermodynamically stable couples has been shortlisted, in which six metals: K, Zr, Hf, Nb, Fe, and Ni, were found to be promising candidates with a high H2S splitting efficiency, high H2yield and good reversible transition between low and high sulfides. The transition between sulfide crystals has been experimentally demonstrated with the Ni3S2/Ni3S2+xcouple. This couple can decompose up to 90 mg H2S/g-Ni3S2at 500 °C to produce H2and high sulfides Ni3S2+xthat was successfully regenerated at 700 °C for multiple cycles. The thermodynamic calculations revealed that the sulfides of Zr, Hf, and Nb are favorable for the two-step H2S splitting process, but have not been explored experimentally. The sulfide of Zr was examined in this work, but they got oxidized by residual oxygen in the test gas before the crystalline transition was detected and remained as a challenge in the future works.

Cefonicid is a common second-generation cephalosporin, and the 7-amino-3-[sulphomethyl-1-H-tetrazol-5-yl-thiomethyl]-3-cephem-4-carboxylate monosodium salt is a key synthetic intermediate in its preparation. Despite the considerable international demand for this antibiotic, its preparation is hampered by low synthetic yield, long reaction time, and time-consuming industrial filtration over charcoal after the purification step. In the context of the industrial production of pharmaceutical intermediates, in which the balance between streamlining and enhancing productivity is necessary in order to compete in the global active pharmaceutical ingredients (API) market, we have investigated an efficient and practical procedure for the synthesis of a key cefonicid intermediate that features a telescopic route whose synthetic steps are all performed at room temperature; from the displacement of the acetoxy group with boron trifluoride to crystallization without treatment with charcoal. In other words, a simpler, scalable, cost-effective and energy-saving protocol is herein reported as a means of moving towards commercial manufacturing. The optimization of the process parameters and the industrial-scale impact assessment should pave the way for industrialization.

Background: Microreactor devices have attracted increasing attention over the last years due to their high surface-to-volume ratio, which ensures a high heat and mass transfer, short molecular diffusion distance and greater spatial illumination homogeneity compared to the traditional reactors. Objective: The aim of this study was to model the kinetics of photo-degradation of 2-propanol over TiO2-based thin films in a gas-phase batch-reactor and simulate their performance in a microreactor device. Methods: The reaction was carried out in a gas-phase batch-reactor, assessing the reactivity of singlelayer nitrogen (N)-doped TiO2 and a bilayer consisting of N-doped TiO2 as a bottom layer and copper (Cu)-doped TiO2 as a top layer. The kinetics of the photocatalytic process was modelled by Langmuir– Hinshelwood (LH) model. The constants obtained from the LH model were used to simulate the performance of the photocatalysts in a microreactor, operating in a continuous flow mode and investigating the effect of the volumetric flow rate (Q), initial concentration of pollutant (Co), number of microchannels (n) and microchannel length (l) on the photo-degradation of 2-propanol. Results: N-Cu-TiO2 exhibited a higher reactivity but a lower adsorption ability towards the target pollutant compared to N-TiO2. To maximize and leverage the advantages of a microreactor, optimal operating conditions for a continuous flow mode, at a steady-state, should be moderately low Q and Co, long l and n that minimizes flow maldistribution in parallel. Conclusion: The findings in this work could serve as a basis to design and fabricate efficient microreactors for the removal of VOC in air purification applications.

TiO2catalysts, modified with acidic or alkaline solutions and then platinized, were used for the partial photocatalytic oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B3under environmentally friendly conditions. The reaction took place in water under UVA light and air oxygen. Catalysts were characterized by TEM, photoluminescence, DRIFT-IR, Raman, DRS, XPS, and photocurrent measurements. The photocatalytic activity results show that Pt loading of untreated samples leads to a significant activity improvement (hence product yield) as much as acid and alkaline treatments do. Moreover, the alkaline treated TiO2samples exhibit a further increase in activity after loading with Pt. Pt acts as an electron scavenger promoting electron transfer from the TiO2conduction band, consequently boosting the photogenerated pair numbers available for the reactive process. Photocurrent measurements show that the TiO2photocatalysts' active sites increase significantly after platinization and alkaline/acid treatment. The treated and/or Pt loaded catalysts showed good thermal stability (at least up to 400 °C).

In this work, the activity enhancement of TiO2photocatalysts by alkaline treatment has been investigated. Commercial (BDH, U.K., anatase phase) TiO2samples, treated in alkaline solutions of NaOH at different concentrations and temperatures, were tested for the photocatalytic partial oxidation of 3-pyridinemethanol in water under UVA irradiation to form vitamin B3. Photocatalyst characterization has been carried out by XRD, BET, TEM, TGA, photoluminescence, FTIR, Raman, DRS, EPR and photocurrent measurements. The alkaline-treated samples showed an increased activity of up to 7 times (by considering first order rate constant values) compared to untreated BDH and the superior performance was maintained even after a thermal treatment at 400 °C, while the selectivity values were affected only marginally by the treatment (being ca.40% and 15% for 3-pyridinemethanal and vitamin B3, respectively). The effect of NaOH concentration and treatment duration on the photocatalytic activity has also been studied extensively. The alkaline treatment has also proven to be effective in modifying the surface properties of another commercial catalyst, i.e., Merck, anatase, improving its reactivity in the conversions of both 4-methoxybenzyl alcohol and 3-pyridinemethanol. The NaOH treatment boosted the porosity and surface area, while lowering the percent crystallinity of the catalysts, due to a higher density of surface hydroxyl groups. It also enhanced the adsorption capability towards the reacting substrate, as shown by FTIR analysis. Despite the oxygen vacancies (or total abundance of Ti3+centres) not being changed after the NaOH treatment, the process of hole trapping under irradiation is drastically affected due to the different water adsorption capabilities of the samples, as highlighted by EPR. The proposed simple treatment of commercial photocatalysts has the potential to support the development of effective photocatalysts, which do not require complex surface modification or doping to achieve high yields in reactions relevant to the chemical industry.

In this paper we describe the identification of two classes of contaminants: sulfonated-PCBs and hydroxy-sulfonated-PCBs. This is the first published report of the detection of these chemicals in soil. They were found, along with hydroxy-PCBs, in soil samples coming from a site historically contaminated by the industrial production of PCBs and in background soils. Sulfonated-PCB levels were approximately 0.4–0.8% of the native PCB levels in soils and about twice the levels of hydroxy-sulfonated-PCBs and hydroxy-PCBs. The identification of sulfonated-PCBs was confirmed by the chemical synthesis of reference standards, obtained through the sulfonation of an industrial mixture of PCBs. We then reviewed the literature to investigate for the potential agents responsible for the sulfonation. Furthermore, we predicted their physicochemical properties and indicate that, given the low pKaof sulfonated- and hydroxy-sulfonated-PCBs, they possess negligible volatility, supporting the case for in situ formation from PCBs. This study shows the need of understanding their origin, their role in the degradation path of PCBs, and their fate, as well as their (still unknown) toxicological and ecotoxicological properties.

We present here an integrated study of the photoelectrochemical and hydrophilic properties of sputtered TiO2thin films, enhanced by means of nitrogen (N) and copper (Cu) doping. We investigated the effect that doping has on both photoelectrochemical efficiency and surface properties by employing a variety of techniques spanning from impedance electrochemical impedance spectroscopy to static contact angle and atomic force microscope (AFM) force spectroscopy before and after UV irradiation through a comprehensive approach able to connect photelectrochemical and hydrophilic performance. Namely, Cu doping was observed to worsen TiO2photoelectrochemical efficiency, unlike N-doping, which instead improved it, whereas both doping enhanced the surface chemistry. Both doping resulted in anodic shift of the flat band potential and in an increase in the donor density with the occurrence of surface defects beneficial for the separation of charge carriers in N–TiO2on one side, and more recombination centers in Cu–TiO2on the other. On the other hand, macroscopic wettability characterization indicated that Cu–TiO2and N–TiO2had a much lower contact angle than TiO2(static contact angle ≈ 20 and 10° for Cu-doped and N-doped films, respectively, as compared to 50° in the bare film) and became superhydrophilic after UV irradiation; AFM corroborated the contact angle data, pointing out that the enhanced hydrophilicity in doped films can be ascribed to an alteration in the surface chemistry because of a greater number of surface defects, such as oxygen vacancies, acting as binding sites for water molecules.

Anatase TiO2samples were synthesized in the presence of different amounts of HF acid with the aim of understanding the effect of the presence of fluorine on the photocatalytic activity. It is well known that the presence of fluoride ions influences the photocatalytic performance by adsorption on the surface of TiO2and that they are capping agents in the control of specific exposed facets. The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption–desorption measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrophotometry, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated in gas–solid and liquid–solid systems by monitoring the oxidation of 2-propanol and 4-methoxybenzyl alcohol, respectively. Some differences in the physico-chemical properties of the different samples were noted; in particular, the presence of F−caused a net decrease of the specific surface area, an increase of the crystallinity degree and an increase of the conductivity, whilst only a slight difference was noted in the distribution of the exposed anatase facets. Moreover, an increase in the total oxidation of 2-propanol and in the selectivity to 4-methoxybenzaldehyde was observed.

•Low temperature sol-gel method was developed to functionalize polymeric membranes.•Vacuum, spray and sol gel coating were tested to make photocatalytic HF membranes.•Sol gel coating yielded higher permeability than spray and vacuum coating.•Membranes were carefully characterized to assess coating impact on their properties.•Coated membranes achieved 30–40% degradation of MB and CHD under solar light.

In the context of sustainable development, the photocatalytic conversion of CO2represents an appealing approach to mitigate climate change while also helping the economy. In this regard, numerous catalysts have been tested for the photoreduction of gaseous CO2; however, the photoconversion of pure liquid CO2has rarely been investigated. This work provides a novel approach for the application of photocatalytic CO2conversion through the utilization of CO2in its pure liquid state. Experimental results show much higher CO yields during the photoreduction of liquid CO2when compared to gaseous CO2. This is ascribed to stronger interactions between CO2and TiO2when considering the solvation effect, as confirmed by DFT calculations. Results also show the positive effect of doping TiO2with copper. The CO yields obtained with liquid CO2, which range from ca. 92–206 mmol·gcat−1, are the highest ever reported.

Soilless farming systems are currently considered a viable production technique reducing environmental impacts due to use of chemical factors, soil and water This study analysed the first high-tech hydroponic greenhouse in Southern Italy, using a Life Cycle Assessment approach. The environmental performances of equipped with automated systems for monitoring the growth environment (high-tech) and soil based without automation of climate and lighting (low-tech) greenhouses were compared. The analysis of high-tech greenhouse was based on primary data from field surveys. For low-tech greenhouse, secondary data from literature were used. The system boundary was from ‘cradle-to-farm-gate’, the functional unit 1 ha of cultivated area. Soil-based cultivation had the highest overall environmental impacts primarily attributable to consumption of fossil fuel and the fertilisers. The results showed that in the high-tech greenhouse, the use of renewable energy and soilless closed-loop cultivation system electronically controlled and managed, significantly reduced the environmental burden. Results suggest solution for the expansion of greenhouse farming improving their environmental performances by renewable energy and closed-loop systems. This study regarding an advanced and almost unique reality is suitable to be reapplied in any context vocated to greenhouses vegetable farming with the foresight to appropriately complement it by economic and social assessments.

Cultural ecosystem services (CES) are non-material intangible benefits that humans derive from ecosystems, which are indispensable for the well-being of communities and directly influence the quality of life. CES are deeply interconnected to each other and to providing and regulating services, thus influencing everyday life. CES are among the most important values that people associate with nature, but understanding them may be challenging. The definition of CES is both self-evident and elusive, specifically because they consist of the interaction between two dynamic systems: human societies and natural ecosystems. This paper updates the state of the art about CES evaluation methods, underlining the gap between their economic values and their incorporation into planning and decision-making on different scales and in different sectors, and emphasizes their importance in conservation policies and sustainable development programs. This study reviewed 68 articles published between August 2019 and May 2023 from the SCOPUS database, and classified CES assessment into 15 evaluation methods. This review reveals that the choice of CES assessment methodologies has often depended on evaluation purposes. In addition, specific CES classifications are required, since different definitions and unstandardized economic concepts for assigning market values to the CES can lead to conflicting results. The combination of different methods, monetary and non-monetary, can aid better evaluation of CES by focusing on the interaction between different components, and can facilitate the mapping and quantification of social values of ecosystem services. This can help decision-makers to develop sustainable territorial planning and policies.

The development of porous metal materials with pore geometries and sizes at the nanoscale offers promising opportunities for the development of smart responsive interfaces for separation and catalytic applications and as building blocks for complex composite materials. Dealloying is an innovative technique based on selective removal of a sacrificial metal from a metal alloy to engineer surface textures and pores across significant thicknesses. Dealloyed structures may be processed over large scales and for a range of source alloys, offering unprecedented manufacturing opportunities. This review presents the operations and challenges of dealloying routes and discusses avenues for process optimizations and improvements, aiming at the development of scalable nanoporous materials. The potential of dealloyed materials for catalytic and sensing applications is expanded and benchmarked against reference materials. Future prospects and applications of dealloyed materials toward surface reactivity control and pore architecture development are highlighted.

There is currently a significant increase in the use of glycerol as a renewable solvent for catalytic reactions. Glycerol has often been the solvent of choice in both homogeneous and heterogeneous catalyses, despite its high viscosity at ambient temperature and the low solubility of highly hydrophobic reagents found in glycerol. Its biodegradability and non-toxicity have led to reports of improved reaction performance and selectivity, as well as easier product separation and effective catalyst recycling. All relevant advances in this emerging field of “green” catalysis are thoroughly reviewed below.

There is currently a significant increase in the use of glycerol as a renewable solvent for catalytic reactions. Glycerol has often been the solvent of choice in both homogeneous and heterogeneous catalyses, despite its high viscosity at ambient temperature and the low solubility of highly hydrophobic reagents found in glycerol. Its biodegradability and non-toxicity have led to reports of improved reaction performance and selectivity, as well as easier product separation and effective catalyst recycling. All relevant advances in this emerging field of “green” catalysis are thoroughly reviewed below.

Ferrite-based materials are becoming increasingly attractive as heterogeneous photocatalysts. Their photocatalytic performance can be limited by fast recombination of charge carriers, particle agglomeration, and low light absorption. Therefore, integrated photocatalytic technologies are one of many options being explored to overcome these limitations. This paper presents a critical review and discussion on the recent application of ferrites-based photocatalysts in the degradation of organic pollutants using integrated photocatalytic technologies such as photocatalytic ozonation (PCO), photo-electrocatalysis (PEC), and sono-photocatalysis (SPC). This review reveals that such integrated photocatalytic technologies offer effective strategies for improving photocatalytic efficiency in the remediation of organic and inorganic pollutants. PCO provides enhanced production of hydroxyl radicals, resulting in high degradation efficiency. PEC provides effective charge carrier separation, thereby improving photocatalytic efficiency. SPC offers high synergy by simultaneously increasing the exposure of active sites and the production of hydroxyl radicals from photo and non-photo catalytic activation. PCO, PEC, and SPC have great potential to accelerate the deployment of advanced photocatalytic (waste)water treatment technology.

Scaling is the bane of households and industries that make use of water frequently. The consequences are so egregious that harmful chemicals have been sought after to remedy the situation. These chemicals, though efficacious, do more harm than good because they render water unsuitable for human consumption and cause ecological imbalance. Anti-scale magnetic water devices offer a cleanersolution to handling the scaling dilemma. This method of water treatment has been in existence for more than a century and is still the subject of much debate today, with the method being viewed with much skepticism, although evidence of its efficacy has been provided on countless occasions. Reports are given on several effects associated with magnetic water treatment, as well as proposed mechanisms. Yet no general consensus has been reached regarding the treatment method's mode of operation, which could explain the cynical reception magnetic water devices often receive. Insights into the enigmatic technique of magnetic water treatment attempt to explain magnetic effects on water and its constituents, citing explanations, which are unrelated to the current principles of magnetism. Several reports and accounts that involve the use and application of anti-scale magnetic water treatment are elucidated with special focus on calcium carbonate scale and its transformation.

A visible light – driven photocatalytic hydrogen production system was evaluated for methanol as a sacrificial agent using a Cu2O/TiO2composite material. A simple ball – milling method was proposed to prepare the Cu2O/TiO2photocatalyst, focusing on those factors influencing the photocatalytic system through a two-level 3-factorial design approach. The effect of the Cu2O loading and the operating conditions (milling time and rotation rate) for the preparation method were analysed. 1% wt. of Cu2O over TiO2was identified as the best formulation for the composite catalyst, achieving a maximum hydrogen production of about 1 mmol/g after 5 h of irradiation. The quantum yield and the light to chemical conversion under visible light conditions for the best performing photocatalyst were 1.51% and 0.6%, respectively, which was about 1.5 – fold higher than that obtained in the presence of a simple mixture of the pure starting powders.

A systematic approach to the design of metal–dielectric multilayer coatings is proposed for energy‐efficient building glazing application. Thirty‐six coatings were modeled with alternating metal (Ag, Au, Cu) and dielectric (TiO2, Ta2O5, ITO, ZrO2, SiO2, Al2O3) thin films in three‐layer (3L) and five‐layer (5L) configurations. It is found that the optical performance is less affected by the bottom dielectric layer compared with the metal and middle/top dielectric layers. The 5L coatings offer a competitive modulation of optical properties, ensuring an optimal balance between luminous transmittance and infrared reflectance. 5L configuration ensures a higher visible transmittance in the whole visible region with peak values close to those of unfunctionalized glass (≈85%), i.e., 3–4% higher compared with the 3L configuration. The optical properties of the optimized multilayers are then used as inputs to building energy models of typical office buildings located in extreme cold and hot weather conditions. The 5L–Ag configurations achieve significant reductions in cooling loads under hot climate conditions (around 15%) without compromising access to daylight (important driver of occupants’ comfort and wellbeing). However, under cold climate conditions, cooling energy savings are outweighed by unintended increases in heating loads, confirming the need for more climate‐driven glazing research efforts. Optical design is conducted on metal–dielectric multilayered coatings to optimize their optical properties for use in energy‐efficient windows. The optical properties of the optimized multilayers are used as inputs to building energy models. The five‐layer coatings with silver as a dielectric ensure the highest reductions in cooling loads under hot climate conditions without compromising access to daylight.

Counting on substrate and oxidation: The Minireview illustrates the use of heterogeneous photocatalysis for performing selective oxidation reactions of alcohols dissolved in water. For instance, the hydroxylation of benzene bearing both, an electron donor group (EDG) or an electron withdrawing group (EWG), and the formation of various aldehydes from the corresponding alcohols are presented.

A new series of leach-proof nanostructured Pd(0) catalysts able to catalyze a number of fundamental organic transformations including C–C bond formation has been developed. Reactions in general proceed with high yield and often at completion, while the catalysts can be reused in further reaction runs. This establishes a new class of relevant solid catalysts for synthetic organic chemistry trademarked SiliaCatPd0Hydrogel.

(Pentamethylcyclopentadienyl)iridium dichloride dimer {[IrCp*Cl2]2}‐catalyzed hydroalkoxylation of bis‐homopropargylic alcohols provides an efficient access to dioxabicyclo[2.2.1]ketals. The cycloisomerizations proceed under mild conditions, with low catalytic loadings and short reaction times. This new protocol involving an Ir(III) catalyst also promoted the cycloisomerization of nitrogen‐tethered 1,6‐enynes to give azabicyclo[4.1.0]heptenes, enhancing the synthetic potential of our method.

The present review is devoted to illustrate the state of the art of the syntheses of indoles, focusing particularly on the most recent developments of new synthetic approaches. Emphasis is given to the preparation of natural products or bioactive compounds containing the indole unit. We present a historical perspective of indole synthesis showing the strategies by choosing the nitrogen precursors. The review is organized sharing the indole synthetic approaches by using different nitrogen-containing functional groups in aromatic substrates used as source of the nitrogen of the indole moiety. Some functional groups and some typical reactions are particularly stressed and highlighted because of the limited coverage given in previous reviews published on this topic. Other synthetic approaches more used and discussed in recent, complete and excellent reviews on the topic are summarized but the most recent published results are highlighted. Our interest is particularly focused on the indolization procedures and on the different methods used for the ring closure and no attention is given to modification of indole structures starting from molecules with a preformed indole unit. Intriguing indole syntheses are continually discovered and the importance that the scientific community gives to these new developments is connected with the strategic role of molecules containing the indole unit. Indoles are the class of heterocycles with more applications and extensive interest due to their biological and pharmacological activity.

Thin‐film flexible photovoltaics are paving the way to low‐cost electricity. Organic, inorganic and organic–inorganic solar cells are deposited over flexible substrates by high‐throughput (often roll‐to‐roll printing) technologies to afford lightweight, economic solar modules that can be integrated into, not installed on, various surfaces. Current conversion efficiencies under standard conditions are in the 3–15 % range, but in real applications the overall productivity is high. These new photovoltaic technologies are ready to provide cheap, clean electricity to the 2 billion people who lack access to the grid as well as to energy‐eager companies and families in the developed world facing the increasing costs of electricity generated using fossil fuel resources. This Review focuses on recent achievements in the area of flexible solar cells, highlights the principles behind the main technologies, and discusses future challenges in this area.

We have developed a three-component, one-pot domino reaction that combines the allylindation of 1H-indole-3-carbaldehyde with the dehydrative alkylation of stabilized Cnucleophiles (e.g., electron-rich heteroarenes, electron-rich aromatics, and stabilized enols) or N nucleophiles (e.g., azoles). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The photocatalytic oxidation of benzyl alcohol (BA) and 4‐methoxybenzyl alcohol (MBA) has been performed in pure water by using commercial TiO2samples (Sigma‐Aldrich, Merck, Degussa P25) and rutile TiO2prepared from TiCl4at low temperature. Particular attention has been devoted to the identification of the produced aromatic compounds along with the formed CO2. Oxidation products such as the corresponding aromatic aldehyde and acid, as well as mono‐ and dihydroxylated aldehydes have been detected. The home‐prepared rutile sample showed a marked selectivity towards the formation of the aromatic aldehyde (38 and 60 % for BA and MBA, respectively), resulting in a three‐ to sevenfold improvement relative to commercial samples, with the only byproduct being CO2. This catalyst was found to be the most selective in the formation of aldehyde in water. By using the commercial or the calcined home‐prepared samples, many hydroxylated aromatic compounds were detected besides the aldehyde and the acid. This finding points to a higher selectivity performance of the home‐prepared rutile relative to the commercial TiO2samples. Some of the home‐prepared samples were also dialysed to check the influence of the presence of Cl−species on catalyst reactivity and selectivity. We have attempted to explain the different reaction rate and selectivity observed for MBA and BA.

Hybrid sol−gel TiO2/organosilica films doped with Cu(II), Fe(II), and Fe(III) phthalocyanines are excellent photocatalysts for the oxidative degradation of organics under visible light irradiation. The films show pronounced stability with the Fe(III)Pc-doped film showing the best performance in the gas-phase mineralization of 2-propanol. The versatile chemistry of both sol−gel materials and phthalocyanines will enable large improvement in terms of performance and technical adaptability of these new photocatalytic devices for future practical application.

Heck couplings were carried out ligandless in air with very low catalyst loads under microwave or simultaneous microwave/ultrasound irradiation. Using ligand-free palladium(II) acetate [Pd(OAc)2] in the range of 0.01–0.1 mol % or palladium-on-carbon (Pd/C) 10 % in the range of 1.0–2.0 mol %, most aryl iodides and bromides gave high yields under conventional heating (120 °C) in 18 4;h. Microwave irradiation alone or, better still, combined with high-intensity ultrasound, strongly promotes the reaction, generally decreasing reaction times to 1 4;h. Electron-poor aryl chlorides such as 4-chloroacetophenone and 1-chloro-4-nitrobenzene reacted with styrene to afford high product yields in the presence of 0.25 mol % Pd(OAc)2 or 2.0–3.0 mol % Pd/C. In several cases the addition of a co-catalyst, either rhodium tris(triphenylphosphine) chloride, 0.005 mol %, or a copper(I) salt (iodide or bromide), 2.0–4.0 mol %, proved very advantageous. 4-Bromo- and 4-chloroacetophenone afforded up to 15 % of oxidation products, namely the corresponding 4-halobenzoic acid and 4-styrylbenzoic acid, a drawback that was avoided by working under a nitrogen atmosphere.

The photocatalytic oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde (PAA) was performed in water with organic-free suspensions of home-prepared and commercial titanium dioxide (TiO2) catalysts. The nanostructured TiO2 samples were synthesised by boiling aqueous solutions of titanium tetrachloride (TiCl4), under mild conditions, for different times. The crystallinity increased with the boiling time. The 4-methoxybenzyl alcohol oxidation rate followed the same pattern but the highest yield (41.5 % mol) to PAA was found for the least crystalline sample, that showed a quantum efficiency of 0.116 %. A comparison with two commercial TiO2 samples showed that all the home-prepared catalysts exhibited a PAA yield higher than that of commercial ones. The only by-products present were traces of 4-methoxybenzoic acid and aliphatic products, carbon dioxide being the other main oxidation product.

We synthesized several sulfur isosters of ferulenol and related prenylcoumarins from Ferula communispreliminary to finding whether the antitubercular activity of these natural compounds might be dissociated from their antithrombin activity. Direct thionation of ferprenine, an instance of “diversityoriented” synthesis, yielded a mixture of three thiocoumarin derivatives. When 4hydroxy2deoxy2thiocoumarin was reacted with farnesal and other α,βunsaturated aldehydes, the isosteric oxygensulfur substitution at position 2 surprisingly caused a regiochemical inversion in the tandem Knoevenagelelectrocyclic reaction, prevalently affording the linear adduct. An extensive investigation with variously substituted enals highlighted a competition between Knoevenagel and Michael addition. This result was rationalized by energy calculations that took into consideration steric and electronic factors as well as complex formation with the catalyst.

The mechanical properties (hardness and elastic modulus) of organically modified silicate thin films can be finely tuned by varying the degree of alkylation and thus the fraction of six- and four-membered siloxane rings in the organosilica matrix. This opens the way to large tunability of parameters that are of crucial practical importance for films that are finding increasing application in numerous fields ranging from microelectronics to chemical sensing.

We describe a new sol-gel molecular electrode made of a thin layer of organosilica doped with the nitroxyl radical TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) electrodeposited on the surface of an ITO-coated glass and its employment as a selective and versatile oxidation catalyst in the electrochemical conversion of different alcohols to carbonyl compounds. Environmentally friendly water or a water/acetonitrile mixture buffered with bicarbonate is used as solvent. The electrode is highly stable and it can be reused for a prolonged period of time allowing easy separation from the products.

Four new ligands for lanthanide ions based on the H3do3a (=1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) structure and bearing one N-sulfonylacetamide arm were synthesized, i.e., H4dota-NHSO2R=10-{2-[(R)sulfonylamino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acids 1a–e. A 15N-NMR study of the 15N-labelled Eu3+ complex of one such ligands, 1d, showed that the coordination of the N-sulfonylacetamide arm involves the carbonyl O-atom rather than the N-atom. The relaxometric properties of the corresponding Gd3+ complexes were investigated as a function of pH and temperature. These complexes have relaxivities in the range 4.5–5.3 4;mM−1 s−1, at 20 4;MHz and 25°, and are characterized by a single H2O molecule in their inner coordination sphere. The mean residence lifetime of this molecule is relatively long (500–700 4;ns) compared to other anionic complexes. The slow rate of H2O exchange can be justified by the extensive delocalization of the negative charge on the N-sulfonylacetamide arm. The long residence time of the coordinated H2O allowed the observation of the effect of the prototropic exchange on the relaxivity. The study of the interaction between the complex [Gd(1e)]- and HSA revealed a weak affinity constant highlighting the importance of a localized negative charge on the complex to promote a strong interaction with the protein.

We have employed high-intensity ultrasound (HIU) to reinvestigate the aldol reaction (AR) in water. A number of aldols that under usual conditions would undergo elimination were isolated in acceptable to good yields. Within 15−30 min, acetophenone reacted with non-enolizable aldehydes to afford the aldol exclusively, while under conventional conditions (stirring or heating under reflux) the same compounds either failed to react or gave, after several hours, the enone, often in complex product mixtures. A library of polyols was obtained starting from a series of acetophenones and excess formaldehyde. Benzaldehyde reacted with a series of 1,3-dicarbonyl compounds to afford the corresponding bis(benzylidene) adducts. The results proved to be highly reproducible because the relevant sonochemical parameters were rigorously controlled. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The three novel pyridine-containing 12-membered macrocyclic ligands 1–3 were synthesized. The coordinating arms are represented by three acetate moieties in 1 and 3 and by one acetate and two phosphonate moieties in 2. In all three ligands, the acetate arm in the distal position is substituted, with a benzyl group in 1 and 2 and with an arylmethyl moiety in 3. The relaxivities r1p (20 MHz, 25°) of Gd^III complexes are: GD·1, r1p=8.3 mM⁻¹ s⁻¹; GD·2, r1p8.1 mM⁻¹ s⁻¹; Gd·3, r1p10.5 mM⁻¹ s⁻¹. ¹H-NMRD and ¹⁷O-NMR T2 data show that Gd·1 and Gd·3 contain two H2O molecules in the inner sphere, whereas the presence of two phosphonate arms allows the coordination of only one H2O molecule in Gd·2. Interestingly, the exchange lifetime of coordinated H2O in the three complexes is similar in spite of the difference in the coordination number of the Gd^III ion (i.e., 9 in Gd·1 and Gd·3, and 8 in Gd·2). ¹H-Relaxometric measurements at different pH and in the presence of lactate and oxalate were carried out to get some insight into the formation of ternary complexes from Gd·1 and Gd·3. Finally, it was found that binding to human-serum albumin (HSA) of Gd·1 and Gd·2, though weak, yields limited relaxivity enhancements, likely as a consequence of effects on the hydration sphere caused by donor atoms on the surface of the protein.

Starting from 4-hydroxy-5-methylcoumarin (7), (±)-preethulia coumarin (3) was synthesized in six steps and in 4% overall yield. The key synthetic procedure was a new type of Lewis acid catalysed, three-component Knoevenagel/hetero Diels−Alder reaction, which employs α-dicarbonyl compounds to generate chromandiones, and vinyl ethers to trap them. Some unexpected rearrangements were observed during the manipulation of various acetalic Diels−Alder adducts, resulting in the serendipitous assembly of bridgehead and fused tetracyclic coumarin assemblies.

A hetero DielsAlder reaction with inverse electron demand between 4hydroxycoumarin, aromatic aldehydes and electronrich alkenes yielded a multitude of 2,4disubstituted 3,4dihydropyranocoumarins. This route opened an easy access to coumarin anticoagulants and provided a library of pyranocoumarin derivatives.

Three novel Gd chelates containing on their external surface pendant phosphonate and carboxylate groups, which promote the interaction with the positively charged groups of polyornithine and polyarginine, have been synthesized. Their solution structures have been assessed on the basis of 1H‐ and 31P‐NMR spectra of the Eu and Yb analogues. A thorough investigation of the relaxometric (1H and 17O) properties of the Gd chelates has been carried out and the observed relaxivities have been accounted for the sum of three contributions arising from water molecules in the first, second, and outer coordination layers, respectively. It has been found that the occurrence of a tight second coordination coating renders the dissociation of the water molecule directly coordinated to the Gd ion more difficult. The binding interactions between the negatively charged Gd chelates and the positively charged groups of polyornithine (ca. 140 residues) and polyarginine (ca. 204 residues) have been evaluated by means of the proton relaxation enhancement (PRE) method. Although the binding interaction decreases markedly in the presence of competitive anions in the solution medium, the affinity is strong enough that in blood serum it is possible to meet the conditions where most of the chelate is bound to the polyamino acid substrate. On this basis one may envisage a novel route for a MRI location of tumors as it is known that positively charged polyamino acids selectively bind to tumors having a greater negative charge than non‐tumor cells.

The fully diethoxyphosphoryl(Dep)-protected polyamines 1b – 3b were prepared from the corresponding polyamines with `diethyl phosphite' (=diethyl phosphonate) and CCl4 in a solid base/organic liquid two-phase system in the presence of Bu4NBr as phase-transfer catalyst. Subsequent phase-transfer-catalyzed alkylation of phosphoramidates 1b – 3b with bis(chloromethyl)arenes 5 – 8 in the presence of Bu4N(HSO4) followed by deprotection gave good yields of polyazacyclophanes 9a – 16a.

AbstractA practical preparation of the versatile macrocycle 1,4,7,10-tetraazacyclododecane (cyclen) was developed starting from cheap and easily available starting materials as ethylenediamine and glyoxal.

Two pairs of new chiral selectors, derived from octakis(6-O-t-butyldimethylsilyl)- and octakis(6-O-t-hexyldimethylsilyl)-γ-cyclodextrin, were synthesized with inverse substitution patterns at the secondary positions. 2-O-methyl-3-O-acetyl- and 2-O-acetyl-3-O-methyl derivatives are suggested as useful models to further investigate the effect of substituents at C-2 and C-3 on the efficiency of enantio-separation using gas chromatography.

This study presents a techno‐economic assessment of a process involving conversion of H2S into hydrogen (a valuable clean fuel) and sulfur. A typical sour gas stream in the oil and gas industry was sweetened by scrubbing with aqueous solution of sodium hydroxide, and the dissolved H2S gas was converted using a TiO2slurry photocatalytic reactor. More details can be found in article number 2100163, Giovanni Palmisano and co‐workers.

The removal of the noxious H2S from natural gas remains a challenging task in the oil and gas industry. Different H2S splitting technologies are proposed and investigated based on the techno‐economic analysis. Herein, the photocatalysis route for H2S splitting represents a potential technology that is not yet fully analyzed. The present study reports a techno‐economic analysis of hydrogen production from H2S via photocatalysis. Guided by the previous experimental result on H2S splitting, Aspen Plus software is used to design and simulate the proposed plant. An economic analysis is performed with CapCost software to estimate the plant capital expenditure (CAPEX) and operational expenditure (OPEX) and the cost of hydrogen production. At 0.485 t H2per h, the process CAPEX is about 105 M$, and OPEX is 143 M$ per year. At a levelized cost of hydrogen (LCOH) production of 1860 $ per t H2, the proposed plant will be able to break even at the end of the plant life. Sensitivity analysis reveals that the process OPEX and price of hydrogen are strongly dependent on the cost of aqueous NaOH. These findings are potentially useful for oil and gas industries looking to incorporate an emerging technology like the presented one in refineries. This study presents a techno‐economic assessment of photocatalytic hydrogen production from H2S and aqueous NaOH solution in a slurry batch reactor. Hydrogen production is simulated using ASPEN plus V8.4 process simulator, and economic calculation is performed using CAPCOST. This process is a potentially sustainable alternative for sour gas sweetening in natural gas processing.

The influence of pH on the photocatalytic partial oxidation of 4-methoxybenzyl alcohol (MBA) and vanillyl alcohol (VA) to their corresponding aldehydes in aqueous suspension under UVA irradiation was investigated by using poorly crystalline home-prepared and crystalline commercial TiO2(BDH, Merck and Degussa P25) photocatalysts. The results clearly show as tuning pH can strongly impart selectivity and activity to photocatalytic processes which are often quite unselective in aqueous suspensions. It was found that pH effect on reaction rate and product selectivity strongly depended on TiO2crystallinity and substrate type. In the case of MBA oxidation, photoreactivity and selectivity were very high at low pH values for all of TiO2catalysts, and the crystalline samples showed to be more active than the poorly crystalline ones. At pH= 1 the photoactivity of Degussa P25 was the highest one, and 88% selectivity at 50% conversion was determined. At acidic pH values, selectivity and activity were higher in the presence of HCl than H2SO4or H3PO4. For VA oxidation, high selectivity values were obtained at high pH’s for all of the samples, and the crystalline samples showed higher activity at the alkaline pH values with respect to that observed at the acidic ones. Experiments starting from the obtained products, that are p-anisaldehyde and vanillin, showed that the selectivity depends on the resistance of those compounds to be subjected to further oxidation under the experimental conditions used.

The formation of a macromolecular adductbetween a suitably functionalized GdIIIcomplex and an exogeneous substance such as a poly‐β‐cyclodextrin (see picture) forms the basis of the novel route to contrast agents for magnetic resonance imaging endowed with high relaxivity discussed herein.

Synthetic protocols for the manipulation of the polyhydroxylated southern region of ingenol (1a) were developed, and a series of isosteres of the anticancer compound ingenol 3,20-dibenzoate (1b) was prepared. The biological evaluation of these compounds showed that cytotoxicity was relatively tolerant to changes at C-20, while PKC activation was markedly affected by these modifications. These data suggest that chemical manipulation can effectively dissect cytotoxicity and tumour-promoting activity (or potential) of ingenoids, affording more optimal candidates for development, like 20-deoxy-20-fluoroingenol 3,20-dibenzoate (5b). In mild acidic medium, an unexpected vinylogous retro-pinacol rearrangement of ingenol to a tigliane derivative was observed.