Mild Conditions Research Articles

Glycogen: A Novel Biopolymer Catalyst for the One-Pot Synthesis of Spirooxindoles, Spiro-Acenaphthylenes, and Spiro-2-Aminopyrans Derivatives under Mild Conditions

Background: Glycogen, a naturally occurring macromolecule, in its granular form and without any post-modification was found to be an efficient and eco-friendly bifunctional heterogeneous organocatalyst. Objective: This catalyst can be useful for the domino synthesis of various spiropyren annulated derivatives through three-component condensation of isathin, malononitrile, and diverse 1,3-dicarbonyl compounds, activated CH-acids, through Knoevenagel-Michael-annulation sequence under mild conditions. Methods: Corresponding spiro derivatives were obtained in high to excellent yields after 5-15 min stirring in 2 mL EtOH and 60°C in the presence of 0.01 g of glycogen, equimolar amounts of isatin/ acenaphthoquinone/ninhydrin, malononitrile, and 1,3-dicarbonyl compounds. Results: FTIR and 1H NMR spectroscopic showed there isn't any catalyst in the media and desired products were obtained in excellent purity. Conclusion: Avoiding any transition metal, one-pot, and multicomponent procedure catalyzed by a biopolymer, broad substrate scope, and operational simplicity are essential features of this methodology for the preparation of medicinally important compounds.

Co-N-C catalyst with single atom active sites for base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under mild conditions

The production of 2,5-furandicarboxylic acid (FDCA), a promising biodegradable alternative to fossil-based terephthalic acid (PTA), from biomass-derived 5-hydroxymethylfurfural (HMF) is of significant importance. A major challenge is to develop an effective non-precious metal catalyst system that does not require a homogeneous base. In this study, we present a noble-metal-free Co-N-C catalyst, derived from the pyrolysis of cobalt-phenanthroline complexes on a carbon support. This catalyst demonstrates exceptional performance, achieving a FDCA yield of 99.9 % and maintaining reusability for up to five catalytic cycles in the base-free oxidation of HMF to FDCA under mild conditions. Through controlled experiments and comprehensive characterizations, we propose that the active sites in the Co-N-C catalyst are Co single atoms bonded to nitrogen within graphitic sheets. This approach provides valuable insights into the exact nature of the active sites in such noble-metal-free M-N-C catalysts designed for biomass conversion

Insights into a photo-driven laccase coupling system for enhanced photocatalytic oxidation and biodegradation

Effective depolymerization of lignin into environmentally friendly aromatic chemicals under mild conditions is gaining interest. Fungal laccase is capable of catalyzing a wide range of reactions, but its low redox potential and preference for acidic pH limit its potential applications. Herein, we developed a laccase-methylene blue (LAC-MB) coupling system, combining the selectivity of enzyme catalysis with the high reactivity of photocatalysis, for the efficient degradation of lignin model compounds. Theoretical calculations indicate that the electron donor’s distance to the LAC’s active site T1 Cu is shortened from 29.7 to 7.3 Å in the LAC-MB. In this system, MB, possessing strong interaction with T1 Cu, acts as a light absorber, enabling the rapid transfer of photogenerated electrons to T1 Cu. This significantly enhances the degradation rate of guaiacol (GUA) from 28.8 % to 91.46 %. The LAC-MB can oxidize both phenolic and non-phenolic lignin model compounds under red-LED irradiation with wide pH ranging from 3.0 to 7.0 and high-efficiency. By tuning the primary coordination sphere and the access tunnel of T1 Cu, we further revealed that enhanced binding affinity and active site accessibility for the LAC-MB complex attributed to the photocatalysis’s high reactivity. Based on this, LAC variants with enhanced binding capabilities were constructed and the resulting mutant LAC-MB are characterized by higher oxygen consumption and ROS generation activated by red-LED, specifically a higher quantum yield of 1O2, demonstrating increased electron transfer and light-driven reactivity. This photo-enzyme coupling system presents a new pathway for the high-efficiency processing of lignocellulosic biomass and offers insights for designing future artificial photosynthetic systems.

Selective Hydrogenation of Furfural into Cyclopentanone Over Composite Metal Catalysts under Mild Conditions

Background/Introduction: The direct hydrogenate conversion of furfural to cyclopentanone is very interesting technology in biomass conversion and utilization. Many kinds of metal catalysts were used in this field, and composite metal catalysts exhibited superior catalytic performance. The hydrogenation process and rearrangement of the furan ring are competitive, polymerization of furfural can prevent the improvement of yield for the main product. Objective: Efficient and high selective catalyst need to be prepared for the improvement the yield of cyclopentanone from hydrogenate conversion of furfural under mild conditions. Methods: Preparation of many composite metal catalysts and catalytic test for the direct hydrogenate conversion of furfural to cyclopentanone. Characterization is chosen to explore the strong metal synergistic effect and micro react mechanism. Results: MCM-41 was chosen as the carrier, and both WO3 and TiO2 were selected as the modifiable assistant, Ru-Cu-WO3@TiO2-MCM-41 were prepared successfully and performed a strong metal synergistic effect in this reaction. The 2%Ru-5%Cu-4%WO3@TiO2-MCM-41 exhibited a 98.54% yield of cyclopentanone when water was chosen as solvent and good stability was found in the recycle tests in mild conditions. Conclusion: A certain amount of WO3 is helpful to enhance the Ru and Cu atoms’ dispersion and the number of acidic sites on the surface of nano catalyst, which may weaken the cracking of C-C bonds and improved the yield of cyclopentanone in mild conditions. A certain amount of TiO2- anatase species adjusted the textural properties of the carrier and show good synergism catalytic function. The best catalytic hydrogenation conversion of furfural was high at 99.75%, and the best selectivity to cyclopentanone was high at 98.79% over 2%Ru-5%Cu-4%WO3@TiO2-MCM-41 catalyst under mild conditions.

Facile synthesis of Metal-Organic Framework/Chitosan cryogel as a robust Scavenger for Diclofenac sodium

Diclofenac sodium (DS), a commonly detected contaminant in aquatic environments, poses a a significant risk to both the ecological balance and the safety of aquatic products. Therefore, efficient removal of DS from water is ergently needed but remains a major challenge. In this study, an environmentally friendly Fe-based metal–organic framework/chitosan (NH2-MIL-53(Fe)/CS) cryogel was prepared through a Schiff base condensation reaction under mild conditions. Taking advantage of the catalytic role of the MOF in accelerating the reaction between CS and 1,3,5-triformylphloroglucinol, NH2-MIL-53(Fe) powders were incorporated into the polymeric networks within 30 s. Owing to the rich binding sites, the resulting NH2-MIL-53(Fe)/CS cryogel demonstrated remarkable efficacy in eliminating DS from water. The adsorption process reached equilibrium within 120 min with a maximum adsorption capacity of 728.6 mg g−1. A comprehensive mechanistic investigation revealed that the exceptional adsorption capability of the NH2-MIL-53(Fe)/CS cryogel for DS was attributed to the synergistic effect of multiple interactions, including favorable hydrophilicity, electrostatic forces, π-π stacking, hydrogen bonding, and coordination. Thus, this study provides a straightforward and rapid synthesis route for MOF/CS cryogel, offering a promising adsorbent that combines exceptional adsorption performance with ease of separation. The resulting MOF/CS cryogel holds great potential for the treatment of DS-contaminated wastewater.

Synergistic regulation of dual thresholds: Hydroxyl occupancy and carbon species in the targeted catalytic hydrocracking of lignite

The preparation of carbon-based catalyst supports from low-grade lignite, followed by its self-catalytic hydrocracking to produce lignite-derived aromatic compounds, is crucial for achieving efficient lignite utilization and expanding aromatic compound sources. During lignite catalytic hydrocracking, the uncontrolled diffusive migration of active hydrogen (H*) and insufficient protection of aromatic rings reduce the yield of aromatic compounds. Using Heishan lignite as the raw material, we employed a relay process of thermal-induced self-assembly and oxidation-mediated carbon distortion for fabricating the Co3O4/AC&GC-S-600 composite material, which features an optimal hydroxyl occupancy ratio and a balanced combination of amorphous carbon/graphite carbon (AC/GC) types. The optimal hydroxyl occupancy threshold balances Co3O4 dispersion and hydrophilicity, facilitating the efficient formation and directional migration of H* through synergistic interaction between Co3O4 and H2O. The adequate threshold of AC/GC ratio regulates substrate adsorption, activation, and inhibition of aromatic hydrogenation, enhancing selective C–O bridge bond cleavage and preserving the unsaturation of aromatic rings. The synergistic regulation of dual thresholds promotes the rapid formation and the directional migration of H*, enabling efficient conversion of Heishan lignite to aromatic compounds (45.8% conversion, 80.8% selectivity) under mild conditions. Characterization techniques, experimental analyses, kinetic studies, and density functional theory calculations confirm that thermally induced self-assembly and oxidation-mediated carbon distortion are crucial for redistributing the carbon framework of the Heishan lignite matrix and regulating the optimal dual thresholds of hydroxyl occupancy and AC/GC types, which are essential for the catalytic hydrocracking of Heishan lignite to aromatic compounds. This strategy provides a scientific basis for selective catalytic production of lignite-based aromatic compounds, thereby supporting its clean and efficient utilization.

Synergistic interplay of CuOx and Pd nanodots on TiO2 for efficient and highly selective photocatalytic oxidation of CH4 to oxygenates with O2

Direct photocatalytic methane oxidation to produce liquid oxygenates offers a promising approach for the upgrading of abundant methane under mild conditions, yet it remains a formidable challenge in achieving high reaction rates while maintaining high selectivity. Herein, we report the highly dispersed CuOx and Pd nanodots decorated TiO2 for photocatalytic oxidation of CH4 with O2 at room temperature, which exhibits a remarkable C1 oxygenates production rate of 39.5 mmol·g−1·h−1 with a nearly 100 % selectivity, outperforming most of the state-of-the-art photocatalysts. Both experimental and theoretical studies suggest that the impressive photocatalytic performance is attributed to the synergy of Cu+ species and Pd nanodots. Cu+ species not only promote the interfacial electrons transfer from TiO2 to Pd, but also mediate CH4 oxidation reaction to avoid overoxidation of oxygenates to CO2, while the resulting electron-rich Pd sites boost the production of primary products (CH3OOH and CH3OH) by lowering the reaction energy. This work provides a new pathway for developing highly efficient photocatalysts for the selective conversion of methane to value-added chemicals by designing bimetallic cocatalysts.

Methylated magnetic covalent organic framework for sample preparation and LC-MS/MS detection of 12 tadalafil analogs in dietary supplements

Tadalafil analogs are often illegally added to dietary supplements such as herbal beverages, protein powders and tablet foods. Due to the complexity of the matrices, effective extraction of tadalafil analogs is the key to achieve accurate quantification. Therefore, it is of great significance to establish a rapid and effective method for the analytical determination of tadalafil analogs in complex matrices. In this study, a novel methylated magnetic covalent organic framework, Fe3O4@TFPB-OT, was successfully synthesized under mild conditions. Fe3O4@TFPB-OT demonstrated robust adsorption capabilities, with capacities ranging from 52.4 to 90.9 mg/g for the tadalafil analogs. Several pre-enrichment parameters were optimized, including adsorbent dosage, extraction time, pH, shaking time, elution solvent, and desorption time. The applicability of Fe3O4@TFPB-OT was evaluated as effective adsorbents for the magnetic solid-phase extraction (MSPE) of 12 tadalafil analogs in dietary supplements. Combined with high-performance liquid chromatography-tandem mass spectrometry, the limits of detection (LODs) of this method ranged from 0.005 to 0.05 μg/L in liquid matrices and from 0.005 to 0.05 μg/kg in solid matrices, showing good sensitivity and recoveries ranged from 56.1 % to 90.9 %with relative standard deviations lower than 3.9 %, demonstrating good accuracy and precision. Additionally, the adsorbent retained its effectiveness after at least ten reuse cycles, indicating significant reusability. This study provides an effective method for the analysis and detection of tadalafil analogs in dietary supplements and has great potential for application.

Microwave assisted treatment of carpentry waste wood flour with natural deep eutectic solvents for nanocellulose production and removal of organic pollutants.

Row carpentry waste wood flour, constituted of poplar (∼60%) and fir (∼30%) biomass, was subjected for the first time to microwave-assisted deep eutectic solvent (DES) treatment, with the purposes of solubilizing lignin and hemicellulose, leaving cellulose as solid residue, thus performing a biorefinery. Several acidic (choline chloride/oxalic acid; choline chloride/citric acid; betaine hydrochloride/oxalic acid) and alkaline (urea/choline chloride; glycerol/K2CO3) DESs were employed under the same reaction conditions. Since the highest extraction yield was obtained by using choline chloride/oxalic acid DES, the use of the latter was investigated by varying some parameters (temperature, manner of microwave irradiation, addition of water) aiming at increasing the solubilization yield, which in fact in some cases reached satisfying values (60%) under mild conditions. The solid residues (SRs) recovered after all treatments with all tested DESs were characterized by Thermogravimetric Analysis (TGA), Attenuated Total Reflectance-Fourier Tranform Infrared Spectroscopy, Solid-State NMR Spectroscopy, and titration of surface acid groups. All SRs were also ultrasonicated to produce cellulose nanoparticles which were in turn characterised by transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. In addition, the solid residues recovered from acidic DESs were able to decontaminate water from organic pollutants, such as p-nitrophenol, by an adsorption process. Thus, the proposed DES treatment efficiently converted carpentry waste wood flour into a valuable biomaterial useful for environmental decontamination.

Vat Photopolymerization 3D Printing of High-Performance Ionic Organogel for Multifunctional Sensors

Ionic gels present a promising solution to meet the growing demand for stretchable and conductive materials in wearable and flexible devices. Compared to ionic hydrogels, which exhibit poor thermal and electrical stability, ionic organogels demonstrate significant potential due to their superior performance characteristics. However, the fabrication of ionic organogels that exhibit high mechanical properties, transparency, and stability remains a significant challenge. In this paper, we report the fabrication of an ionic organogel using vat photopolymerization 3D printing with Projection Micro-Stereolithography technology under mild conditions. The 3D-printed ionic organogel exhibits outstanding transparency (93.81% in the range of 400-800nm), high stretchability (elongation at break of 2782%), tunable mechanical properties, excellent ionic conductivity, electrical stability with a high decomposition voltage of 4V, and thermal stability up to 300°C. The strain sensor based on the ionic organogel is capable of monitoring human movement, including both large-scale movements and subtle signals, with high sensitivity and extreme-temperature tolerance. In addition, the ionic organogel-based pressure and temperature sensor with dual functionality demonstrates excellent temperature and pressure sensing capabilities, even at extreme temperatures up to 100°C (boiling point of water). Thus, the as-fabricated ionic organogel presents an excellent choice of material for wearable and flexible devices, particularly for applications operating in harsh and extreme-temperature environments.

Innovative synthesis and practical application of graphitic carbon nitride/α-zirconium phosphate in visible light-activated Knoevenagel condensation

To advance the development of efficient photocatalysts activated by visible light for environmental applications. We employed a simple approach to synthesize g-C3N4/α-ZrP composite in different mass ratios, followed by comprehensive characterization through several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM/EDS), and UV–Visible diffuse reflectance spectra (DRS). Furthermore, the g-C3N4/α-ZrP with mass ratio 6:1 was demonstrated high performance catalytic activity in Knoevenagel condensation (Yield 88 %–96 %) in a short reaction time (5–20 min) under visible light irradiation. The use of g-C3N4/α-ZrP has transformed the traditional synthesis of carbon–carbon double bonds, offering improved reaction rates and reduced by-products. These next-generation photocatalysts also exhibit remarkable properties that facilitate the activation of substrates under milder conditions, opening up new possibilities for green and sustainable synthesis. This advancement contributes to the development of environmentally friendly and efficient synthetic methodologies.

Unprecedented synthesis of indole-linked tetra-substituted alkenes by catalyst-free domino reaction

Herein, we report a simple, efficient catalyst-free green domino reaction of indole, arylglyoxal, and cyclic 1,3-dicarbonyls such as barbituric acid derivatives/dimedone at 100oC in dimethylformamide medium in open air condition. In this reaction, one C-C and one C=C bonds have been formed in one-pot without using any additive or metal based reagent. Considering the presence of indole, benzoyl and cyclic 1,3-dicarbonyl moieties in the products, it is expected that they will exhibit interesting medicinal properties. All the synthesized products were characterized by recording FTIR, 1H NMR, 13C NMR, and HRMS. Moreover, a single crystal XRD of compound 4i was recorded to confirm the structure of the product. Operational simplicity, gram-scale synthesis, mild reaction conditions, good yields, and wide substrate scope are the salient features of this methodology.

Multicomponent Synthesis of Structurally Diverse Spiroheterocycles using Bio-organic Catalyst in Aqueous Medium

Background: MCRs are one of the most significant tools in the synthesis of organic compounds. MCR is a rapid chemical technique that uses three or more reactants to produce products that sustain all structural and substructural properties of the initial components. MCRs are useful in all fields of synthetic chemistry because of their rapid rate of reaction, simple procedure and excellent yields. We reported an efficient and environmentally friendly domino approach for the synthesis of spiroheterocycles spiro annulated with indeno[1,2-b]quinoline. Method: The spiroheterocycles with privileged heterocyclic substructures have been synthesized using taurine (2-aminoethanesulfonic acid) as a green, sustainable, bio-organic and recyclable catalyst in a three-component reaction of isatins, 1,3-diketones, and 1-napthylamine in aqueous media. The present synthetic method is probably the first report to synthesize spiroheterocycles, spiroannulated with indeno[1,2-b]quinoline. Furthermore, the approach is valuable because of the excellent yield that results from the reaction in 15-20 min. Result: The optimization of reaction conditions is an important case of efficient synthesis. The solvent, temperature, time and catalyst loading were all examined. The reusability of the catalyst was also investigated experimentally. The used catalyst taurine has a high activity as well as good reusability. The present synthetic protocol will be extended to synthesise a library of hybrid compounds. The present synthetic approach is cost-effective, and time-efficient with an easy-workup methodology that gives outstanding yields (80–95%) in 15–20 min. Conclusion: Taurine-catalyzed multicomponent reaction is a novel and efficient method for the synthesis of spiroannulated indeno[1,2-b]quinolines. The high catalytic activity of taurine as a catalyst with water as a green solvent makes the process environmentally friendly. The special features of the synthetic protocol include synthetic efficiency, operational simplicity, and reusability of the catalyst and it is expected to make significant contributions not only to drug discovery studies but also to pharmaceutical and therapeutic chemistry in view of introducing molecular diversity in the synthesized molecules.

Non-noble Co supported on Beta framework for hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to renewable biofuel 2,5-dimethylfuran

Selective transformation of biomass platform molecule 5-hydroxymethylfurfural (HMF) into biofuel 2,5-dimethylfuran (DMF) through hydrogenolysis path has attracted significant attention in the field of biomass catalytic conversion. In general, this process required supported noble catalysts under elevated temperature (423-533 K) and enough H2 pressure (1-4 MPa). Herein, Co/Beta-DA catalysts with various Co loadings of 5-20 wt% were post-synthesized through wet impregnation. Benefiting from the relatively open channel systems and strong metal-support interactions, the obtained 10Co/Beta-DA with ∼10 wt% Co contents facilitated the hydrogenation of C=O bonds and the cleavage of C-O bonds, which was efficient for the selective hydrogenolysis from HMF to DMF (Conv.HMF ≥ 99.9%, Sel.DMF ≥ 99.9%) under mild reaction conditions (H2 pressure, 1.0 MPa; temp., 423 K; time, 3 h). The innovative strategy of designing and preparing rational non-noble impregnated zeolite provided brand-new perspectives to solve the problems of high cost and harsh reaction conditions in the HMF hydrogenolysis process, which has the potential to convert biomass into renewable liquid fuels.

Gallium Sulphide (Ga2S3): Green, Reusable, and Efficient Nanocatalyst for the Synthesis of 3,3-(arylmethylene)-bis-(4-hydroxycoumarin) Under Solvent-free Condition

: Our current work's primary goal is to create novel heterogeneous gallium sulfide (Ga2S3) nanocatalysts and investigate their catalytic activity in the synthesis of 3,3-(arylmethylene)-bis-(4- hydroxycoumarin) derivatives without use of solvent. FT-IR, XRD, SEM, and EDX analysis characterized the synthesized gallium sulfide (Ga2S3) nanomaterial catalysts. This method's main benefits are its short reaction time, solvent-free conditions, extremely mild reaction conditions, good product yield, and, most importantly, its ability to recover catalysts after at least four runs.

Ultrasound-assisted Adsorptive Desulfurization of Dibenzothiophene from Model Fuel on K2CO3-Activated Biochar

A novel mesoporous activated biochar (ABC) was developed from an equal mix of date and olive stones and implemented in the ultrasound-assisted adsorptive desulfurization (USADS) of model gasoline (300 ppm DBT/n-hexane) and model kerosene (300 ppm DBT/cyclohexane). The biowaste blend was carbonized at 450°C for 75 min at a 10°C/min heating rate, followed by K2CO3-activation. The superior ABC was synthesized at 750°C for 1h using an impregnation ratio of 1:1 K2CO3: biochar. The BET surface area and average pore diameter of the resulting ABC were 1099.70 m2/g and 5.14 nm, respectively. The USADS of both models was achieved at relatively mild experimental conditions (0.20 g of the ABC 30°C, 40 min, and 120 W US power). At these conditions, the USADS of model gasoline amounted to 97.32 % compared to 99.39 % for model kerosene. The USADS process of both models followed the Langmuir model of the adsorption isotherms and the pseudo-2nd-order kinetics model. The ABC was recoverable and effective until the 5th regeneration cycle and reused reasonably. The maximum USADS of real gasoline (88.12 %) was achieved using 1.0 g of the ABC at 30°C for 120 min.

Fe-promoted Ni nanocatalysts for hydrogenolysis of Klason lignin to monophenols

The efficient cleavage of lignin's inter-unit bonds is essential for its conversion into valuable monophenols. However, conventional Ni-based catalysts often suffer from poor metal dispersion, sintering, and limited catalytic activity. In this study, a series of bimetallic Ni2M/Al2O3 (M=Fe/In/Mn/Cu/Co) catalysts were synthesized using layered double hydroxides as precursors. Among the metal promoters tested, Fe showed the highest efficacy in improving catalytic performance. NixFey/Al2O3 catalysts with varying Ni/Fe molar ratios exhibited superior activity due to the formation of Ni-Fe alloys and defect-rich FeOx species. The optimized Ni1.5Fe1.5/Al2O3 catalyst, characterized by well-dispersed small metal particles, strong Ni-Fe interactions, abundant surface oxygen vacancies, and a high density of strong acid sites, achieved a monophenol yield of 16.6 wt% from the hydrogenolysis of Klason lignin under mild reaction conditions (240°C, 4 hours, 1 MPa initial H2). This work presents a novel approach for developing highly active bimetallic catalysts for lignin depolymerization, offering insights into the design of efficient catalysts for lignin valorization.

Carbonate-mediated Mars-van Krevelen mechanism on CuxO/CeO2 catalysts for boosting CO oxidation

Copper-cerium-based catalysts have gained considerable attention for their excellent performance in low-temperature CO oxidation applications. In this context, the carbonate-mediated Mars-van Krevelen (M−vK) pathway stands out as a promising route for enhancing catalytic performance. Herein, we prepared three CuxO/CeO2 nanocatalysts with varying copper content using Cu2O nanocrystals (Cu2O NCs) and Ce-BTC metal–organic frameworks (MOFs) as dual precursors. The optimal catalyst exhibits excellent performance (T100 value of 110 °C) comparable to the precious metal catalyst. Through integrating in-depth experimental results and density functional theory (DFT) calculations, we reveal the intricate interplay of interfacial synergistic catalysis and carbonate-mediated M−vK mechanisms, confirming that carbonate species generated under mild conditions significantly promote CO oxidation on CuxO/CeO2 nanocatalysts. Based on the comparison of the transition state (TS) energy barrier between the traditional and the carbonate-mediated M−vK mechanism reaction paths, we found that carbonate species is easier to form and establish the rate-determining step (viz., carbonate → CO2, the energy barrier of 1.51 eV). This study sheds light on the importance of carbonate species in modulating the catalytic behaviour of copper-cerium catalysts and provides valuable insights for designing efficient catalysts for CO oxidation applications.

Highly Selective On‐Surface Dehydrogenative Aromatization of n‐Hexyl to Phenyl Substituents

AbstractDehydrogenative aromatization of alkyl substituents represents a powerful approach to aryl‐substituted functional molecules. However, the inertness of alkyl groups and the need for harsh reaction conditions accompanied by low product selectivity hamper its widespread applications. Here, we demonstrate the highly selective on‐surface thermal aromatization of n‐hexyl substituents on polycyclic aromatic hydrocarbons (PAHs) to their phenyl‐substituted analogues under mild conditions. After depositing two representative precursor molecules, n‐hexyl‐substituted hexaphenylbenzene (HPB‐Hex) and bianthryl octacarboxylic tetraimide (BATI‐Hex), onto a pre‐heated Au(111) substrate, dehydroaromatization of the peripheral n‐hexyl groups into phenyl rings occurs, following the planarization of hexaphenylbenzene and bianthryl core. This process involves sequential intramolecular C−C bond rotations, dehydrogenation, and cyclodehydrogenation reactions, yielding phenyl‐substituted hexabenzocoronene (HBC‐Ph) and bisanthene octacarboxylic tetraimides (BSTI‐Ph). The reaction sequences were monitored using scanning tunneling microscopy (STM) and bond‐resolved non‐contact atomic force microscopy (nc‐AFM), offering structural proof of both intermediates and final products. These experimental techniques were complemented by density functional theory (DFT) simulations, which facilitated the detection of crucial steps in the conversion of n‐hexyl to phenyl groups. Moreover, the effect of alkyl aromatization on the electronic properties of the newly formed aromatic hydrocarbons was elucidated using scanning tunneling spectroscopy (STS).

Controlled hydrogenation of furfural to furfuryl alcohol or cyclopentanone over Ni–P under mild conditions

Controlled hydrogenation of furfural to furfuryl alcohol or cyclopentanone over Ni–P under mild conditions