In this investigation, solvent polarity and viscosity effects coupled with the concentration effect on the photophysical behavior of a formyl fluorene derivative ( AF ) have been explored by stationary and ultrafast spectroscopies. The femtosecond spectroscopic results pointed out the formation of a double triplet state with a short lifetime characteristic of a singlet and spectral features of the triplet state. Moreover, efficient triplet exciton separation was observed with a triplet yield in a trend with solution concentration that reaches values higher than 100% and up to 140% in viscous medium at high concentration. The latter finding definitively corroborated the presence of an unconventional INTRA + INTERmolecular singlet fission (SF) mechanism: INTRAmolecular formation of the correlated triplet pair 1 TT, followed by INTERmolecular triplet separation via a “super‐diffusional” triplet–triplet energy transfer process. Interestingly, small changes in solvent dielectric constant/polarizability have been found to be very effective in modulating the S 1 ‐ 1 TT energy gap pointing to a slightly endothermic SF in toluene and an exothermic SF in the less polar cyclohexane and decahydronaphthalene. Moreover, femtosecond fluorescence up‐conversion measurements of AF in Tol unveiled delayed fluorescence from S 1 and proper emission of 1 TT and allowed the quantum yield for these processes to be separated and roughly estimated (∼0.01 for both of them).

In recent years, the focus on luminescent solar concentrator (LSC) materials has been renewed thanks to their properties that support their integration into PV technologies in buildings and in the urban environment. In this work, three dyes bearing push-pull units and presenting anthracene (compound 1) or 2,1,3-benzothiadiazole (BTZ-P6t, compound 2, and TBTZ-P12t, compound 3) as the central chromophore module are investigated as luminophores for the LSCs based on polyacrylate. The optical and luminescence characterization of the dyes in solution and in polyacrylate panels has been carried out to examine the impact of medium polarity and stiffening on the photophysical behavior of the dyes. The photoluminescence quantum yield (PLQY), decay times, and radiative and nonradiative rate constants have been evaluated together with the overlap integral to rationalize the reabsorption phenomena. The photophysical parameters highlight that medium polarity and matrix stiffening have an impact on the photoluminescence properties. The evaluation of the photovoltaic performance, performed by placing an edge of dye panels in contact with a silicon PV device, shows that the panels act as LSCs. In particular, compound 3 exhibits the highest value of PLQY (81%), resulting in the highest value of PV light-to-energy conversion efficiencies (ηopt%, 2.8%). This study proposes a thorough and correlated examination of the photophysical characteristics of molecular systems when the media are switched from solution to acrylate panels in order to rationalize the photovoltaic performance of the prepared LSCs. Although the prepared dye-acrylate panels fall outside accepted standard dimensions for LSC size, this study is relevant to designing chromophore architecture for enhanced efficiencies for LSCs.

Asphaltene-derived materials have been successfully demonstrated as effective anode materials for Li-ion batteries. Pyrolyzed asphaltene used as an anode exhibited a specific capacity of up to 420 mAh g−1, significantly surpassing that of well-known commercial graphite and raw asphaltene. The battery anode made from pyrolyzed asphaltene also displayed excellent rate capabilities, even at a high 5 °C-rate. Both pyrolyzed asphaltene and N-doped pyrolyzed asphaltene demonstrated strong cycle performance, underscoring their potential as high-performance anode materials.

This study presents the synthesis and characterization of six small-molecule benzo[1,2-b:5,4-b']dithiophene (BDT) derivatives incorporating acetylenic bonds and various thienyl-based substituents, designed for application in solution-processable organic field-effect transistors (OFETs). Structural variations included pristine, linear alkylated, and branched alkylated thiophene and bithiophene units. Thermal, optical, electrochemical, and theoretical properties of these molecules were systematically analyzed, along with characterization of thin-film morphologies and microstructure via AFM and XRD measurements. All derivatives demonstrated sufficient solubility in toluene, affirming compatibility with solution process. Among the compounds, the unsubstituted molecule (compound 1) exhibited the highest hole mobility (up to 0.16 cm2/Vs) with average hole mobility (0.086 cm2/Vs) and marked film crystallinity. This enhancement is attributed to its high molecular planarity and rigidity, induced by the acetylenic linkage. In contrast, compounds functionalized with alkyl chains or bithiophene units exhibited increased molecular distortion, poor crystallinity, and significantly reduced OFET performance. These results underline the critical role of structural planarity and minimal steric hindrance in achieving high-performance OSCs, simultaneously highlighting the potential performance degradation from improper functionalization.

Lignocellulosic biomass, rich in cellulose, hemicellulose, and lignin, represents a promising renewable resource. However, lignin, a complex polyphenolic material, remains underutilized despite its surplus production. This review focuses on the conversion of lignin into macromonomers for polymer production. While lignin's potential in polymer science is gaining recognition, studies focusing specifically on lignin-based macromonomers remain limited. This review addresses this gap by discussing the synthesis of lignin macromonomers and their role in polymer synthesis. It also highlights the potential and challenges of sourcing lignin from agri-food waste, with the goal of inspiring advancements and fostering innovation in the development of more sustainable and circular polymer systems.

Lignocellulosic biomass, a rich and underutilized source of lignin, presents considerable potential for advancing sustainable electronic materials. This review explores the lignin’s role in organic transistor-based devices, considering its integration into various components. It highlights lignin’s structural and chemical characteristics that influence its performance in such devices, along with key factors affecting its processability, interfacial behavior, and compatibility with existing organic electronic materials. By outlining current research directions and emerging applications, this work aims to provide a foundation for further exploration of lignin-based thin films in next-generation, green organic electronics.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a highly promising biodegradable and bio-based thermoplastic recognized for its environmental benefits and potential versatility. However, its industrial adoption has been limited due to its inherent brittleness and suboptimal processability. Despite these challenges, PHBV’s performance can be tailored for a wide range of applications through strategic modifications, particularly by blending it with other biodegradable polymers or reinforcing it with natural fibers and bio-based fillers. This study explores the potential of brewers’ spent grain (BSG) as a sustainable source for the development of PHBV biocomposites. The biocomposites were synthesized by incorporating arabinoxylan-bound benzoate, which can be derived from BSG, as a sustainable filler at concentrations of 4% and 10% w/w. The resulting materials were characterized using tensile testing, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The findings demonstrate that the incorporation of functionalized arabinoxylan significantly enhances the mechanical properties of PHBV, preserves its thermal stability, and increases its crystallinity (from 59.9% to 67.6%), highlighting a positive impact on both material performance and processing characteristics.

The growing global population has intensified waste generation, creating significant environmental and sustainability challenges particularly in the agri-food sector, where large volumes of residues are generated demanding efficient management and valorization. In this regard, brewer's spent grains (BSG), the main byproduct of the brewing industry, offers a valuable opportunity for valorization due to its rich composition. This study presents a strategy to valorize BSG by selectively extracting protein, phenolic compounds, and oligosaccharides, which are compounds with numerous applications in the food area. To reduce energy and water costs, wet BSG was used, eliminating the need for a drying step. A sequential process combining enzymatic hydrolysis and hydrothermal treatment was performed, achieving high extraction yields for protein (65 %) and oligosaccharides (91 %). Additionally, protein extraction using alcalase enzyme in a mild alkaline medium (pH 8.5) facilitated the recovery of phenolic compounds (1.1 g GAE/100 g dry BSG). Hydrothermal treatment was highly efficient and selective to recover oligosaccharides (i.e., gluco-, xylo-, and arabino-oligosaccharides) free of impurities such as furfural, 5-hydroxymethylfurfural, and acetic acid. These findings highlight a viable approach for the selective extraction of high-purity compounds from BSG, offering a sustainable strategy for its valorization.

This study introduces a sustainable approach for enhancing the fire retardancy and smoke suppression of poly(lactic acid) (PLA) composites, contributing to addressing one of the major challenges in biocomposites that limits their application in various engineering fields, as automotive and construction sectors. Flax fibers (FF) were surface functionalized with a novel organic-inorganic hybrid flame retardant (FR), offering a sustainable bioinspired approach that mitigates potential mechanical properties impairment and FR leaching, which can cause environmental concerns and reduced composite durability. The process involves a three-step coating procedure. First, the flax fibers (FF) are pretreated with ozone to promote carboxylic group formation (FF-O3); subsequently, gallic acid (GA) units are covalently immobilized on the fiber surface (FF-GA); finally, the hybrid FR iron phenylphosphonate is complexed with the phenolic groups of GA units (FF-GA-FeP). Fourier transform infrared (FT-IR) analysis of FF-GA-FeP confirmed the presence of specific absorptions associated with the deposited FR coating. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed changes in fiber morphology and confirmed the incorporation of iron and phosphorus. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy and X-ray WAXS microscopy revealed that fibers' crystallinity was not significantly affected by derivatization. Microwave plasma atomic emission spectroscopy (MP-AES) detected a precise 0.1 wt% iron loading. Using FF-GA-FeP as reinforcement in PLA-based composites (PLA/FF-FeP) resulted in enhanced thermal stability and flame retardancy of the composites, with minimal coating application, as revealed by thermogravimetric analysis (TGA) and cone calorimetry tests (CCT). A decrease in peak of heat release rate (pHRR), total smoke release (TSR), specific extinction area (SEA), and Fire Propagating Index (FPI) of 5, 87, 68, and 9.5 %, respectively, was achieved for PLA/FF-FeP, compared to untreated flax fiber reinforced PLA (PLA/FF). Furthermore, preliminary tensile tests indicate minor changes in tensile strength and a slight increase in stiffness of the PLA/FF-FeP compared to PLA/FF. Hence, in the biocomposite, the immobilization of a minimal amount of iron phenylphosphonate directly on the flax fiber surface proved to be an effective strategy for smoke suppression while preserving the mechanical integrity of the composite.

This study investigates the effectiveness of citric acid as a salt crystallization inhibitor aimed at improving the durability and mechanical performance of concrete exposed to marine environments. The goal is to evaluate whether the addition of citric acid can mitigate the deterioration of concrete caused by salt crystallization during wet–dry cycles and simulated wave impacts. The novelty of this work lies in the experimental demonstration that a simple and environmentally friendly organic compound can effectively reduce salt-induced damage in marine-exposed concrete. Concrete samples were subjected to repeated wet–dry cycles and simulated marine wave impacts to assess changes in their physical and elastic properties. Variations in P-wave and S-wave velocities, Young’s modulus, and the effects of salt crystallization within the concrete matrix were evaluated through acoustic measurements. Results show that citric acid significantly reduces internal cracking, stiffness loss, and salt accumulation, leading to enhanced structural integrity and greater resistance to environmental stressors. These findings highlight the potential of citric acid as a sustainable additive for improving the long-term durability and mechanical stability of concrete structures in marine environments.

Hydrothermal carbonization (HTC) serves as a sustainable method to transform pine needle waste into nitrogen-doped (N-doped) hydrochars. The primary focus is on evaluating these hydrochars as catalytic electrodes for the oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR), which are pivotal processes with significant environmental implications. Hydrochars were synthesized by varying the parameters such as nitrogen loading, temperature, and residence time. These materials were then thoroughly characterized using diverse analytical techniques, including elemental analysis, density measurements, BET surface area analysis, and spectroscopies like Raman, FTIR, and XPS, along with optical and scanning electron microscopies. The subsequent electrochemical assessment involved preparing electrocatalytic inks by combining hydrochars with an anion exchange ionomer (AEI) to leverage their synergistic effects. To the best of our knowledge, there are no previous reports on catalytic electrodes that simultaneously incorporate both a hydrochar and AEI. Evaluation metrics such as current densities, onset and half-wave potentials, and Koutecky–Levich and Tafel plots provided insights into their electrocatalytic performances. Notably, hydrochars synthesized at 230 °C exhibited an onset potential of 0.92 V vs. RHE, marking the highest reported value for a hydrochar. They also facilitated the exchange of four electrons at 0.26 V vs. RHE in the ORR. Additionally, the CO2RR yielded valuable C2 products like acetaldehyde and acetate. These findings highlight the remarkable electrocatalytic activity of the optimized hydrochars, which could be attributed, at least in part, to their optimal porosity.

In this work, detailed experimental proof and in-depth analysis of the singlet fission (SF) mechanism, operative in fluorene-based small molecules, are carried out by employing advanced time-resolved spectroscopies with nanosecond and femtosecond resolution. The investigation of the effect of solution concentration and solvent viscosity together with temperature and excitation wavelength demonstrates INTRAmolecular formation of the correlated triplet pair followed by INTERmolecular independent triplet separation via a "super-diffusional" triplet-triplet transfer process. This unconventional INTRA- to INTERmolecular SF may be considered an "ideal" mechanism. Indeed, intramolecular formation of the correlated triplet pair is here interestingly proved for small molecules rather than large multichromophoric systems, allowing easy synthesis and processability while maintaining good control over the SF process. On the other hand, the intermolecular triplet separation may be exploited to achieve high triplet quantum yields in these new SF small molecules.

A sustainable, bioinspired approach to functionalize basalt fibers with an innovative gallic acid (GA)-iron phenyl phosphonate complex (BF-GA-FeP), for the purpose of improving the flame retardancy in composite materials, is developed. BFs were at first pretreated with O3, obtaining surface free hydroxyl groups that allowed the subsequent covalent immobilization of biosourced GA units on the fiber through ester linkages. Phenolic -OH groups of the GA units were then exploited for the complexation of iron phenyl phosphonate, resulting in the target-complex-coated BF fiber (BF-GA-FeP). Microwave plasma atomic emission spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analyses of BF-GA-FeP highlighted an increase in iron content, modification of fiber morphology, and occurrence of phosphorus, respectively. BFs, modified with a low amount of the developed complex, were used to reinforce a poly(lactic acid) (PLA) matrix in the production of a biocomposite (PLA/BF-FeP). PLA/BF-FeP showed a higher thermal stability than neat PLA and PLA reinforced with untreated BFs (PLA/BF), as confirmed by thermogravimetric analysis. The cone calorimeter test highlighted several advantages for PLA/BF-FeP, including a prolonged time to ignition, a reduced time to flame out, an 8% decrease in the peak heat release rate, and a 15% reduced fire propagating index compared to PLA/BF.

Green chemistry and engineering seek for maximizing efficiency and minimizing negative impacts on the environment and human health in chemical production processes. Driven by advances in the principles of environment protection and sustainability, these fields are expected to greatly contribute to achieving sustainable development goals. To this end, many studies have been conducted to develop new approaches within green chemistry and engineering. The Advances in Green Chemistry and Engineering Collection at Scientific Reports aims at gathering the latest research on developing and implementing the principles of green chemistry and engineering.

Beer is the most consumed alcoholic beverage worldwide, and its production involves the generation of a huge volume of by-products (i.e., spent grain, spent hop, and spent yeast). This review aims to highlight the main properties of these by-products as a valuable source of biomolecules (i.e., proteins, cellulose, hemicellulose, lignin, phenolic compounds, and lipids) and the biorefining methods used in the last decade for their valorization. The pros and cons of the technologies employed will be shown, highlighting which of them could be more ready for the transition to an industrial scale, and which applications (e.g., food and feed, bioenergy, biochemicals, and biomaterials) are the most feasible.

This research aligns with sustainability goals, wherein hydrochar derived from the hydrothermal treatment of brewing industry waste was employed as a support for a ruthenium-based catalyst. Hydrochar-supported Ru metal (Ru-HC) was synthesized and applied in the reductive amination pathway within the H-cube, a flow reactor coupled with a hydrogen source. The reductive reaction between levulinic acid and n-butylamine was chosen as a model reaction. High conversion and high selectivity were obtained after optimization with temperature, flow rate, hydrogen pressure and solvents. At 40 bar of hydrogen pressure, 80 degrees C of temperature, with a flow of 0.1 mLmin-1, 99% conversion with selectivity of 98% towards the hydrogenated product was obtained. The catalytic ability of Ru-HC was investigated across a variety of substrate scopes. Several biomass-derived molecules such as furfural, 5-hydroxymethylfurfural, furfurylamine etc. were employed in the reductive amination process to yield diverse valuable N-containing products. The possible mechanism was further proved with the formation of an intermediate and a recyclability study proved the robust nature of Ru-HC. Overall, the established pathway for reductive amination with Ru-HC as a heterogeneous catalyst provides a sustainable protocol for the synthesis of N-containing molecules, which is highly valuable for our society.

Two new benzo[b]thieno[2,3-d]thiophene (BTT) derivatives, 2-(benzo[b]thiophen-5-yl)benzo[b]thieno[2,3-d]thiophene (compound 2), and 2-(benzo[b]thieno[2,3-d]thiophene-2yl)dibenzo[b,d]thiophene (compound 3) have been synthesized and utilized as solution-processable small molecular organic semiconductors for organic field-effect transistors (OFETs). The physicochemical characteristics of the recently created substances were analyzed using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and UV-vis spectroscopy. Subsequently, the above-mentioned substances were employed as semiconductor layers in bottom-gate/top-contact OFETs through solution shearing methods for device fabrication, and their electrical performances were meticulously evaluated. The outcoming OFET device displayed p-channel behavior, demonstrating hole mobility of up to 0.005cm2/Vs and a current on/off ratio higher than 106.

The conversion of levulinic acid (LA) into alkyl levulinates is highly significant due to the wide range of applications for these products, including their use as fuel additives, solvents, and fragrances. In order to meet the growing need for environmentally friendly chemical production, this study takes a circular economy approach by upcycling a common urban waste, i.e., pine needles, to synthesize a robust heterogeneous acid catalyst, subsequently used to efficiently upgrade LA into levulinates. By utilizing a single-step procedure under mild operating conditions, the resulting PiNe–SO3H catalyst demonstrated good performances and flexibility in synthesizing diverse bio-derived levulinates. In fact, the catalyst showed an exceptionally broad range of applicability, resulting in isolated yields ranging from ̴ 46% to ̴ 93%, which is an unprecedented achievement. The catalyst's ability to be reused was tested, revealing remarkable performance for up to 10 consecutive cycles with negligible loss in efficiency. Additionally, a significant focus was directed towards developing a method that minimizes waste during the isolation process. This involved optimizing reaction conditions and rationalizing work-up procedures, resulting in low Environmental factor (E-factor) values ranging from 1.2 to 8.9. To comprehensively assess the overall environmental sustainability of the process, various additional green metrics were calculated, and the Ecoscale tool was employed as well. Furthermore, mechanistic investigations elucidated the favored reaction pathway, underscoring that, under the optimized conditions, the prevailing mechanism entails direct esterification, as opposed to the generation of a pseudo-ester intermediate.

The brewing industry plays a significant role in producing a substantial annual volume of by-products, which contributes to the global accumulation of food waste. The primary by-product generated is brewer's spent grain (BSG), a lignocellulosic biomass rich in proteins, fiber, and moisture content. Leveraging biorefining and valorization techniques for BSG represents a promising strategy to enhance sustainability, resilience, and circularity within the brewing chain. To date, most studies have focused on extracting proteins from BSG. Yet, it is crucial to note that the fiber part of BSG also holds considerable potential for biorefining processes. This study introduces a novel sequential extraction method designed to integrally recover the major components of BSG. Notably, it introduces a reactive extraction approach that enables the simultaneous extraction and tuneable functionalization of the hemicellulose component. Additionally, the study assesses the utility of the attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy as a user-friendly tool to monitor and evaluate the effectiveness of the fractionation process. This spectroscopic technique can provide valuable insights into the changes and composition of BSG throughout the extraction process.

Bio-based glycerol and aldehydes have been valorized by acetalization reaction over novel macroporous sulfonated polystyrene-type resins (MR-SP20-SO3H and MR-SP50-SO3H). The influence of reactants molar ratio, catalyst amount, temperature, and reaction time on the activity and selectivity to acetals have been investigated. Results showed that MR-SP20-SO3H and MR-SP50-SO3H confirm a high performance in the acetalization of the glycerol derivatives 1,2- propandiol, 1,3-propandiol, 3-methoxy-1,2-propandiol and monoacetin; these catalytic systems enable recover and reuse.