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De novo design of organic photocatalysts: bithiophene derivatives for the visible-light induced C-H functionalization of heteroarenes
摘要： Herein, we report the de novo synthesis and characterization of a series of substituted bithiophene derivatives as novel inexpensive organic photocatalysts. DFT calculations were used to predict a priori their absorption spectra and redox potentials, which were then confirmed with empirical data. The photocatalytic activity of this novel class of organic photoredox catalyst was demonstrated in two visible-light mediated strategies for the C-H functionalization of heteroarenes. The implementation of these strategies in a continuous-flow photo-microreactor afforded moderate to excellent yields within few minutes of reaction time. Due to their straightforward synthesis, low cost and good photocatalytic properties we believe that the proposed bithiophene derivatives could be employed as a new class of organic photoredox catalysts.
关键词： Organic photocatalysts,C-H functionalization,Photoredox catalysis,DFT calculations,Continuous flow catalysis
更新于2025-09-04 15:30:14
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Controllable Synthesis and Catalytic Performance of Gold Nanoparticles with Cucurbit[n]urils (n = 5–8)
摘要： A series of gold nanoparticles (AuNPs) was prepared in situ with different cucurbit[n]urils (CB[n]s) in an alkaline aqueous solution. The nanoparticle sizes can be well controlled by CB[n]s (n = 5, 6, 7, 8) with different ring sizes. The packing densities of CB[5–8] and free surface area on AuNPs were determined. A direct relationship was found between the ring size and packing density of CB[n]s with respect to the AuNP-catalyzed reduction of 4-nitrophenol in the presence of NaBH4. The larger particle size and higher surface coverage of bigger CB[n]-capped AuNPs significantly decreased the catalytic activity. Furthermore, this work could lead to new applications that utilize AuNPs under an overlayer of CB[n]s for catalysis, sensing, and drug delivery.
关键词： gold nanoparticles,catalysis,cucurbit[n]urils,controllable synthesis
更新于2025-09-04 15:30:14
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Amidyl Radical Directed Remote Allylation of Unactivated sp3 C-H Bonds via Organic Photoredox Catalysis
摘要： The development of visible-light-mediated allylation of unactivated sp3 C-H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre-functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C-H allylation products in good yields. A variety of electron deficient allyl sulfone systems could be used as δ-carbon radical acceptor.
关键词： amidyl radical,eosin Y,metal free,photoredox catalysis,Unactivated C-H Bonds
更新于2025-09-04 15:30:14
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Faceting and metal-exchange catalysis in (010) β-Ga <sub/>2</sub> O <sub/>3</sub> thin films homoepitaxially grown by plasma-assisted molecular beam epitaxy
摘要： We here present an experimental study on (010)-oriented β-Ga2O3 thin films homoepitaxially grown by plasma assisted molecular beam epitaxy. We study the effect of substrate treatments (i.e., O-plasma and Ga-etching) and several deposition parameters (i.e., growth temperature and metal-to-oxygen flux ratio) on the resulting Ga2O3 surface morphology and growth rate. In situ and ex-situ characterizations identified the formation of (110) and (ˉ110)-facets on the nominally oriented (010) surface induced by the Ga-etching of the substrate and by several growth conditions, suggesting (110) to be a stable (yet unexplored) substrate orientation. Moreover, we demonstrate how metal-exchange catalysis enabled by an additional In-flux significantly increases the growth rate (>threefold increment) of monoclinic Ga2O3 at high growth temperatures, while maintaining a low surface roughness (rms < 0.5 nm) and preventing the incorporation of In into the deposited layer. This study gives important indications for obtaining device-quality thin films and opens up the possibility to enhance the growth rate in β-Ga2O3 homoepitaxy on different surfaces [e.g., (100) and (001)] via molecular beam epitaxy.
关键词： molecular beam epitaxy,metal-exchange catalysis,surface morphology,homoepitaxy,β-Ga2O3
更新于2025-09-04 15:30:14
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Piezotronic modulations in electro- and photochemical catalysis
摘要： Electrochemical catalyst design and optimization primarily relies on understanding and facilitating interfacial charge transfer. Recently, piezotronics have emerged as a promising method for tuning the interfacial energetics. The unique band-engineering capability using piezoelectric or ferroelectric polarization could lead to performance gains for electrochemical catalysis beyond what can be achieved by chemical or structural optimization. This article addresses the fundamentals of surface polarization and corresponding band modulation at solid–liquid interfaces. The most recent advances in piezotronic modulations are discussed from multiple perspectives of catalysis, including photocatalytic, photoelectrochemical, and electrochemical processes, particularly for energy-related applications. The concept of piezocatalysis, a direct conversion of mechanical energy to chemical energy, is introduced with an example of mechanically driven water splitting. While still in the early stages, piezotronics is envisioned to become a powerful tool for revolutionizing electrochemical catalysis.
关键词： electrochemical catalysis,piezotronics,piezoelectric polarization,piezocatalysis,ferroelectric polarization
更新于2025-09-04 15:30:14
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Metal–Organic Frameworks for Photocatalysis and Photothermal Catalysis
摘要： To meet the ever-increasing global demand for energy, conversion of solar energy to chemical/thermal energy is very promising. Light-mediated catalysis, including photocatalysis (organic transformations, water splitting, CO2 reduction, etc.) and photothermal catalysis play key roles in solar to chemical/thermal energy conversion via the light?matter interaction. The major challenges in traditional semiconductor photocatalysts include insufficient sunlight utilization, charge carrier recombination, limited exposure of active sites, and particularly the difficulty of understanding the structure?activity relationship. Metal?organic frameworks (MOFs), featuring semiconductor-like behavior, have recently captured broad interest toward photocatalysis and photothermal catalysis because of their well-defined and tailorable porous structures, high surface areas, etc. These advantages are beneficial for rational structural modulation for improved light harvesting and charge separation as well as other effects, greatly helping to address the aforementioned challenges and especially facilitating the establishment of the structure?activity relationship. Therefore, it is increasingly important to summarize this research field and provide in-depth insight into MOF-based photocatalysis and photothermal catalysis to accelerate the future development.
关键词： Charge separation,Photocatalysis,Light harvesting,Solar energy conversion,Photothermal catalysis,Metal?organic frameworks
更新于2025-09-04 15:30:14
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Nonresonant photons catalyze photodissociation of phenol
摘要： Phenol represents an ideal polyatomic system for demonstrating photon catalysis because of its large polarizability, well-characterized excited-state potential energy surfaces, and nonadiabatic dissociation dynamics. A nonresonant IR pulse (1064 nm) supplies a strong electric field (4 x 107 V/cm) during the photolysis of isolated phenol (C6H5OH) molecules to yield C6H5O + H near two known energetic thresholds: the S1/S2 conical intersection and the S1 - S0 origin. H-atom speed distributions show marked changes in the relative contributions of dissociative pathways in both cases, compared to the absence of the nonresonant IR pulse. Results indicate that nonresonant photons lower the activation barrier for some pathways relative to others by dynamically Stark shifting the excited-state potential energy surfaces rather than aligning molecules in the strong electric field. Theoretical calculations offer support for the experimental interpretation.
关键词： phenol,photodissociation,dynamic Stark shift,photon catalysis,nonresonant IR field
更新于2025-09-04 15:30:14
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<i>In My Element</i> : Yttrium
摘要： After a near 7-year pathway devoted solely to late transition metal systems, my hunt in the world of catalysis drove me progressively towards the very left side of the periodic table. Group 4, then group 3, and now group 2 elements. Rare-earths and alkali-earths are really unique elements. Even though going down those two columns and running through the lanthanide row, physicochemical properties most often vary monotonously, their reactivity remains sometimes quite mysterious: who has ever truly rationalized the “peak activity” of neodymium catalyst systems in diene and ethylene polymerization?! But my favorite element isn’t neodymium: its paramagnetism makes for too nasty an NMR spectra to satisfy a molecular chemist in the search for understanding what’s going on in the coordination sphere… No, my special one is yttrium. This one is diamagnetic, providing beautiful, informative NMR spectra. And, importantly for the single-site polymerization catalysis community, some complexes of this abundant element have proved really unique in the ring-opening polymerization of cyclic esters, featuring high activity and unequaled stereocontrol abilities—not unrelated to its small size, which makes for a crowded, discriminative coordination sphere.
关键词： rare-earths,polymerization,alkali-earths,yttrium,catalysis
更新于2025-09-04 15:30:14