Benzyl Aldehyde Research Articles

Efficient hole extraction to reactive oxidation sites over a Co3O4/Cs3Sb2Br9 p-n heterojunction for enhanced benzylic C(sp3)-H bond oxidation

Photocatalytic selective oxidation of aromatic hydrocarbons plays an important role in the production of value-added chemicals. A key step in this process is the activation of C(sp3)-H bond by photogenerated holes. However, the inadequate hole generation and lack of surface adsorption-activation sites severely hinders the improvement in photocatalytic C-H bond oxidation. In particular, the random charge migration to the surface impedes the effective capture of holes by surface active sites to dissociate the C(sp3)-H bond. Here, we design and fabricate a Co3O4/Cs3Sb2Br9 p-n heterojunction that effectively addresses these challenges. The p-n heterojunction forms strong built-in electric fields (BEF) facilitating spatial charge separation. Holes are accumulated on Co3O4, while electrons are accumulated on Cs3Sb2Br9, thereby offering abundant active holes and electrons. Moreover, Co3O4 shows stronger adsorption and activation capacity for the C(sp³)-H bond, enabling the C(sp3)-H bond dissociation with low reaction energy barrier. Consequently, the holes are directionally extracted from photoactive Cs3Sb2Br9 to catalytically active Co3O4 under visible light irradiation, thereby accelerating the toluene oxidation. The optimized 5 % Co3O4/Cs3Sb2Br9 exhibits a benzyl aldehyde (BAD) evolution rate of 5044 μmol g−1 h−1 and a benzyl alcohol (BA) production rate of 1820 μmol g−1 h−1, which are 12 and 17 times higher than that of blank Cs3Sb2Br9, respectively.

Thermo physical properties and IR spectral studies of some binary liquid mixtures and correlation with the Jouyban–Acree model

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of propargyl alcohol (J) with benzyl aldehyde (J1), benzylamine (J2) and benzyl alcohol (J3) components with selected compositions were determined from the measured values of densities (ρ), viscosities (η), and speeds of sound (u) of pure components and their mixtures from 303.15 K to 313.15 K. The effect of various functional groups on the excess properties has been discussed in terms of attractive forces between the components. The results of the Jouyban-Acree model are discussed in terms of the mean relative deviation and individual relative between the calculated and experimental densities, speed of sound, and viscosities as an accuracy criterion.FTIR studies have also been added to confirm the experimental findings of the investigated mixtures

Engineering MPC-Assisted Heterojunctional Photo-Oxidation Tailored by Interfacial Design of a P-Modulated C3N4 Heterojunction for Improved Aerobic Alcohol Oxidation.

The creation of two-dimensional van der Waals (VDW) heterostructures is a sophisticated approach to enhancing photocatalytic efficiency. However, challenges in electron transfer at the interfaces often arise in these heterostructures due to the varied structures and energy barriers of the components involved. This study presents a novel method for constructing a VDW heterostructure by inserting a phosphate group between copper phthalocyanine (CuPc) and boron-doped, nitrogen-deficient graphitic carbon nitride (BCN), referred to as Cu/PO4-BCN. This phosphate group serves as a charge mediator, enabling effective charge transfer within the heterostructure, thus facilitating electron flow from BCN to CuPc upon activation. As a result, the photogenerated electrons are effectively utilized by the catalytic Cu2+ core in CuPc, achieving a conversion efficiency of 96% for benzyl alcohol (BA) and a selectivity of 98.8% for benzyl aldehyde (BAD) in the presence of oxygen as the sole oxidant and under illumination. Notably, the production rate of BAD is almost 8 times higher than that observed with BCN alone and remains stable over five cycles. The introduction of interfacial mediators to enhance electron transfer represents a pioneering and efficient strategy in the design of photocatalysts, enabling the proficient transformation of BA into valuable derivatives.

Guest-Regulated Generation of Reactive Oxygen Species from Porphyrin-Based Multicomponent Metallacages for Selective Photocatalysis.

The development of novel materials for highly efficient and selective photocatalysis is crucial for their practical applications. Herein, we employ the host-guest chemistry of porphyrin-based metallacages to regulate the generation of reactive oxygen species and further use them for the selective photocatalytic oxidation of benzyl alcohols. Upon irradiation, the sole metallacage (6) can generate singlet oxygen (1O2) effectively via excited energy transfer, while its complex with C70 (6⊃C70) opens a pathway for electron transfer to promote the formation of superoxide anion (O2⋅-), producing both 1O2 and O2⋅-. The addition of 4,4'-bipyridine (BPY) to complex 6⊃C70 forms a more stable complex (6⊃BPY) via the coordination of the Zn-porphyrin faces of 6 and BPY, which drives fullerenes out of the cavities and restores the ability of 1O2 generation. Therefore, benzyl alcohols are oxidized into benzyl aldehydes upon irradiation in the presence of 6 or 6⊃BPY, while they are oxidized into benzoic acids when 6⊃C70 is employed as the photosensitizing agent. This study demonstrates a highly efficient strategy that utilizes the host-guest chemistry of metallacages to regulate the generation of reactive oxygen species for selective photooxidation reactions, which could promote the utilization of metallacages and their related host-guest complexes for photocatalytic applications.

Guest‐Regulated Generation of Reactive Oxygen Species from Porphyrin‐Based Multicomponent Metallacages for Selective Photocatalysis

AbstractThe development of novel materials for highly efficient and selective photocatalysis is crucial for their practical applications. Herein, we employ the host‐guest chemistry of porphyrin‐based metallacages to regulate the generation of reactive oxygen species and further use them for the selective photocatalytic oxidation of benzyl alcohols. Upon irradiation, the sole metallacage (6) can generate singlet oxygen (1O2) effectively via excited energy transfer, while its complex with C70 (6⊃C70) opens a pathway for electron transfer to promote the formation of superoxide anion (O2⋅−), producing both 1O2 and O2⋅−. The addition of 4,4′‐bipyridine (BPY) to complex 6⊃C70 forms a more stable complex (6⊃BPY) via the coordination of the Zn‐porphyrin faces of 6 and BPY, which drives fullerenes out of the cavities and restores the ability of 1O2 generation. Therefore, benzyl alcohols are oxidized into benzyl aldehydes upon irradiation in the presence of 6 or 6⊃BPY, while they are oxidized into benzoic acids when 6⊃C70 is employed as the photosensitizing agent. This study demonstrates a highly efficient strategy that utilizes the host‐guest chemistry of metallacages to regulate the generation of reactive oxygen species for selective photooxidation reactions, which could promote the utilization of metallacages and their related host‐guest complexes for photocatalytic applications.

Thermophysical properties of binary liquid mixtures at various temperatures, supported by FTIR spectral studies and correlation with the Jouyban–Acree model (allyl alcohol, benzyl aldehyde, benzylamine and benzyl alcohol)

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of allyl alcohol (C) with benzyl aldehyde (C1), benzylamine (C2) and benzyl alcohol (C3) components in selected compositions were determined from the measured values of densities (ρ), viscosities (η) and speeds of sound (u) of pure components and their mixtures at 303.15–313.15 K. These results were analysed by different theoretical models, such as PFP and Jouyban–Acree model. The effect of various functional groups on the excess properties was discussed in terms of disruption of H-bonding and dipole–dipole interaction between the components of the mixtures. The thermodynamic results of the present investigation have been correlated with FTIR spectral studies and have obtained a good agreement.

Catalytic Hydrogenation Property of Methyl Benzoate to Benzyl Aldehyde over Manganese-Based Catalysts with Appropriate Oxygen Vacancies

The synthesis of benzaldehyde, a compound widely utilized in food, medicine, and cosmetics, was achieved through a one-step catalytic hydrogenation using the cost-effective raw material, methyl benzoate. This process aligns with the principles of atom economy and green production. Despite the development of numerous high-performance catalysts by scholars, the challenge remains in achieving lower reaction temperatures, ideally below 400 °C. In this study, a series of MnOx/γ-Al2O3 catalysts were meticulously prepared using the precipitation-impregnation method. These catalysts featured supports calcined at various temperatures and distinct manganese active components. Characterization techniques such as X-ray diffraction (XRD), N2 physical adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), and NH3 temperature-programmed desorption (NH3-TPD) were employed to analyze the structure and surface properties of the catalysts. Notably, the optimized reaction temperature was found to be 360 °C. The catalyst exhibited the most favorable performance when the calcination temperature of the support was 500 °C and the Mn/Al molar ratio reached 0.18. Under these conditions, the catalyst demonstrated the most suitable oxygen vacancy concentration, yielding impressive results: a conversion rate of 87.90% and a benzaldehyde selectivity of 86.1%. These achievements were attained at 360 °C, atmospheric pressure, a hydrogen to methyl benzoate molar ratio of 40:1, and a Gas Hourly Space Velocity (GHSV) of 800 h−1. This research underscores the potential for optimizing catalysts to enhance the efficiency and sustainability of benzaldehyde synthesis.

Mass spectrometric monitoring of ligand-bridged hot electron transfer and anaerobic oxidization on auto renewable droplet-based plasmonic nanoreactors under visible light illumination

The light induced hot-electron on plasmonic nanostructures has been recognized as a breakthrough discovery for photovoltaic and photocatalytic applications. With mass spectrometry, we demonstrate the dynamics of hot electron transfers of anaerobic oxidization reactions on Au decorated TiO2 plasmonic nanoparticles, which were coated on the inner surface of a flask. Those nanoparticles were covered by continuously renewed liquid droplets of solvent and reactants that were transported through a Venturi jet mixer with auto-spray. In addition to intensive mass transfer in such droplet-based nanoreactors, as well as strong adsorption of reactants and rapid desorption of products on materials surfaces, the localized surface plasmon resonance (LSPR) excitation upon visible light illumination, by which accumulated energies of plasmons are transferred to electrons in the conduction band of the material, attributes to the efficient photocatalytic transformation. Mass spectrometric detection of intermediate radical anions and negative ions with stable isotope labeling unambiguously identifies that highly energetic hot electrons can escape from the plasmonic nanostructures, be collected by adsorbed molecules, and initiate bond cleavages. It was demonstrated that losses of two H atoms result in the anaerobic oxidization of each benzyl alcohol molecule to a benzyl aldehyde molecule in the absence of molecular oxygen with more than 90 % yields. The well recyclable plasmonic nanoreactors implicate the injection of transferred electrons eventually back to electronically depleted Au+ positive ions. Bridged by adsorbed molecules, electrons were repeatedly circulated back and forth in plasmonic nanoreactors, where the collected light was eventually converted into chemical energy.

In-situ construction of FAPbBr3-wrapped MoS2 heterostructure for photocatalytic H2 evolution from dehydrogenation of aromatic alcohols

Photocatalytic H2 evolution from organics dehydrogenation has sparked tremendous research attention. Metal halide perovskites (MHPs) with unique photoelectrical properties are deemed as a promising new-generation photocatalysts. Here, FAPbBr3-wrapped MoS2 heterostructure photocatalysts are in-situ constructed by an anti-solvent method for photocatalytic dehydrogenation of aromatic alcohols, which realizes a co-production of clean H2 fuel and value-added aldehydes. Experimental characterizations and theoretical calculations disclose that the introduction of MoS2 decreases the size of the FAPbBr3, and forms a built-in electric field in the composite, which synergistically inhibit the electron-hole pairs recombination and enhance the charge separation. Meanwhile, the MoS2 with low hydrogen binding energy provides abundant reduction sites to accelerate the kinetic of H2 evolution. As a consequence, the optimal FAPbBr3/MoS2-7 composite exhibits a H2 evolution rate of 1150 μmol g−1 h−1 and a benzyl aldehyde (BAD) generation rate of 1040 μmol g−1 h−1 under visible light irradiation, which is about 6 times of blank FAPbBr3. The activity is comparable to the reported value of H2 production from photocatalytic haloid acid splitting using MHPs-based catalysts. Electron paramagnetic resonance (EPR) measurement reveals that carbon-centered radical of •CH(OH)Ph is the primary intermediate for the photocatalytic dehydrogenation of aromatic alcohols.

Tuning redox ability of Zn3In2S6 with surfactant modification for highly efficient and selective photocatalytic C-C coupling

Heterogeneous photocatalytic C-C coupling is a green and efficient approach to producing valuable chemicals. The strategies for guiding effective photocatalyst design are desired but still limited. Here, we report visible-light-driven highly selective photocatalytic C-C coupling of benzyl alcohol over surfactant-modified Zn3In2S6 semiconductors. A complete switch of product selectivity from benzyl aldehyde (91.5 %) to C-C coupling products (96.5 %) is obtained by the modification of Zn3In2S6 with stearyl trimethyl ammonium bromide (STAB). This modification assists the formation of sulfur vacancies on Zn3In2S6 to enhance charge carrier separation, thereby increasing the photocatalytic activity. The selectivity switch is mainly attributed to increasing conduction band position of Zn3In2S6 by surfactant modification which strengthens the reduction ability of photogenerated electrons to induce the reversible reduction of benzyl aldehyde to ketyl radicals, and partially to the poor oxidation ability of the material that inhibits the oxidation of ketyl radicals to benzyl aldehyde. Encouragingly, this universal protocol has been successfully applied to a series of aromatic alcohols and biomass-derived furanic alcohols to selectively produce C-C coupling products.

Photocatalytic Anaerobic Oxidation of Aromatic Alcohols Coupled With H2 Production Over CsPbBr3/GO-Pt Catalysts.

Metal halide perovskites (MHPs) have been widely investigated for various photocatalytic applications. However, the dual-functional reaction system integrated selective organic oxidation with H2 production over MHPs is rarely reported. Here, we demonstrate for the first time the selective oxidation of aromatic alcohols to aldehydes integrated with hydrogen (H2) evolution over Pt-decorated CsPbBr3. Especially, the functionalization of CsPbBr3 with graphene oxide (GO) further improves the photoactivity of the perovskite catalyst. The optimal amount of CsPbBr3/GO-Pt exhibits an H2 evolution rate of 1,060 μmol g−1 h−1 along with high selectivity (>99%) for benzyl aldehyde generation (1,050 μmol g−1 h−1) under visible light (λ > 400 nm), which is about five times higher than the CsPbBr3-Pt sample. The enhanced activity has been ascribed to two effects induced by the introduction of GO: 1) GO displays a structure-directing role, decreasing the particle size of CsPbBr3 and 2) GO and Pt act as electron reservoirs, extracting the photogenerated electrons and prohibiting the recombination of the electron–hole pairs. This study opens new avenues to utilize metal halide perovskites as dual-functional photocatalysts to perform selective organic transformations and solar fuel production.

Improved visible-light activities of ultrathin CoPc/g-C3N4 heterojunctions by N-doped graphene modulation for selective benzyl alcohol oxidation

The interface modulation is the key factor affecting the photoactivity of metal phthalocyanine (MPc)/g-C3N4 heterojunctions for aerobic selective alcohol oxidation. Here, we have successfully fabricated the N-doped graphene-modulated CoPc/g-C3N4 nanosheets (CoPc/NG/CN) heterojunctions. Optimal CoPc/NG/CN photocatalyst demonstrates approximately fourfold photoactivity improvement for benzyl alcohol oxidation with ∼99% selectivity toward benzyl aldehyde and of approximately ninefold 2,4-dichlorophenol degradation rate compared with bare CN, using O2 as oxidant. By means of steady-state surface photovoltage responses in N2 atmosphere, time-resolved photoluminescence spectra, single-wavelength photocurrent action spectra, and electrochemical O2 reduction measurements, it is confirmed that the exceptional photoactivities of resulting CoPc/NG/CN heterojunction are attributed to the facilitated interfacial charge transfer between CoPc and CN by the modulation of NG with favorable electron-induced capacity. In addition, more enriched hydroxyl groups of NG by N doping could induce high dispersion of CoPc molecules via H-bonding effect, resulting in the increase of exposed number of CoPc as visible-light absorption units and single Co2+ sites as catalytic centers for O2 activation so as to further benefit the photocatalytic oxidation processes. This work provides a feasible interfacial modulation strategy to fabricate efficient supported MPc-based heterojunction photocatalyst nanomaterials.

Integration of Metabolome and Transcriptome Reveals the Relationship of Benzenoid-Phenylpropanoid Pigment and Aroma in Purple Tea Flowers.

Tea (Camellia sinensis) flowers are normally white, even though the leaves could be purple. We previously discovered a specific variety with purple leaves and flowers. In the face of such a phenomenon, researchers usually focus on the mechanism of color formation but ignore the change of aroma. The purple tea flowers contain more anthocyanins, which belong to flavonoids. Meanwhile, phenylalanine (Phe), derived from the shikimate pathway, is a precursor for both flavonoids and volatile benzenoid–phenylpropanoids (BPs). Thus, it is not clear whether the BP aroma was attenuated for the appearance of purple color. In this study, we integrated metabolome and transcriptome of petals of two tea varieties, namely, Zijuan (ZJ) with white flowers and Baitang (BT) with purple flowers, to reveal the relationship between color (anthocyanins) and aroma (volatile BPs). The results indicated that in purple petals, the upstream shikimate pathway promoted for 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS) was elevated. Among the increased anthocyanins, delphinidin-3-O-glucoside (DpG) was extremely higher; volatile BPs, including benzyl aldehyde, benzyl alcohol, acetophenone (AP), 1-phenylethanol, and 2-phenylethanol, were also enhanced, and AP was largely elevated. The structural genes related to the biosynthesis of volatile BPs were induced, while the whole flavonoid biosynthesis pathway was downregulated, except for the genes flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′,5′-hydroxylase (F3′5′H), which were highly expressed to shift the carbon flux to delphinidin, which was then conjugated to glucoside by increased bronze-1 (BZ1) (UDP-glucose: flavonoid 3-O-glucosyltransferase) to form DpG. Transcription factors (TFs) highly related to AP and DpG were selected to investigate their correlation with the differentially expressed structural genes. TFs, such as MYB, AP2/ERF, bZIP, TCP, and GATA, were dramatically expressed and focused on the regulation of genes in the upstream synthesis of Phe (DAHPS; arogenate dehydratase/prephenatedehydratase) and the synthesis of AP (phenylacetaldehyde reductase; short-chain dehydrogenase/reductase), Dp (F3′H; F3′5′H), and DpG (BZ1), but inhibited the formation of flavones (flavonol synthase) and catechins (leucoanthocyanidin reductase). These results discovered an unexpected promotion of volatile BPs in purple tea flowers and extended our understanding of the relationship between the BP-type color and aroma in the tea plant.

Switchable All Inorganic Halide Perovskite Nanocrystalline Photoelectrodes for Solar‐Driven Organic Transformations

All inorganic halide perovskite nanocrystals (NCs) are considered as fascinating materials for a wide range of optoelectronic applications encompassing photovoltaics, lasing, sensing, and photocatalysis due to their outstanding optoelectronic properties. Herein, it is demonstrated that the photoelectrochemical behavior of CsPbBr3 NC films can be tailored through engineering the selective contacts and accepting species in the electrolyte. This concept has been successfully applied to the photoelectrochemical oxidation of benzyl alcohol (BzOH) to benzyl aldehyde (BzCHO) and the reverse photoelectrochemical reduction of BzCHO to BzOH, demonstrating that CsPbBr3 NCs activate both reactions with photocurrents up to 40 μA cm−2 toward BzCHO production and 5 μA cm−2 for the reverse reaction at 0.15 V versus normal hydrogen electrode. The obtained results highlight the huge potential and versatility of halide perovskite NCs for photoelectrocatalytic applications, validating the implementation of these materials for a wide range of solar‐driven complex organic transformations, and emphasizing the urgent need for stabilization strategies to move beyond the proof‐of‐concept stage to relevant technological developments.

Ultrasound-assisted decoration of CuOx nanoclusters on TiO2 nanoparticles for additives free photocatalytic hydrogen production and biomass valorization by selective oxidation

• Ultrasound-assisted ultra-wet (US-UWet) impregnation synthetic method is presented. • Mixed cupric and cuprous oxides nanoclusters (< 4 nm) were decorated on TiO 2 P25. • The nanocomposite showed H 2 formation capability under low power UV irradiation. • The additive free oxidation of biomass derived model platform chemicals was studied. • Nanocomposite revealed higher selectivity comparing to P25 for HMF and BnOH oxidation. The herein presented ultrasound-assisted ultra-wet (US-UWet) impregnation synthetic approach was followed in order to avoid the drawbacks of the conventional wet impregnation synthesis. The goal was to homogeneously decorate the surface of the TiO 2 nanoparticles with nanometric sized (< 4 nm) clusters of mixed cupric and cuprous oxides. The physicochemical features of the nanocomposite (TiO 2 CuO x ) were determined by high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and Diffuse reflectance (DR) spectroscopy. TiO 2 CuO x showed an enhanced and continuous capability to generate molecular hydrogen upon low power ultraviolet irradiation. The benchmark commercial TiO 2 P25 did not reveal any H 2 formation under these conditions. TiO 2 CuO x presented also a high efficiency for the additives-free selective partial oxidation of two well established biomass derived model platform chemicals/building blocks, 5-hydroxymethylfurfural (HMF) and benzyl alcohol (BnOH) to the value-added chemicals 2,5-diformylfuran (DFF) and benzyl aldehyde (PhCHO), respectively. The nanocomposite showed higher DFF and PhCHO yield compared to P25.

Mild oxidation of benzyl alcohols to benzyl aldehydes or ketones catalyzed by visible light

Induced by visible light, mild oxidation condition to prepare benzyl aldehydes or ketones have been developed by using bromotrichloromethane as photochemical oxidant. This method avoids high temperature, pressure and peroxidation with only visible light as the green driving force.

Visible-near-infrared-light-driven selective oxidation of alcohols over nanostructured Cu doped SrTiO3 in water under mild condition

Cu doped SrTiO3 (Cu-STO) has been synthesized and investigated as the photocatalyst for selective alcohol oxidation under mild condition. Cu-STO samples demonstrate intense absorption to visible light and near-infrared light. Using water as the reaction solvent, Cu-STO samples can efficiently oxidize benzyl alcohol (BA) into benzyl aldehyde under both anaerobic and aerobic conditions with high selectivity. In aerobic condition, an apparent quantum efficiency as high as 43.22% at 420 nm has been reached for benzyl alcohol oxidation. More strikingly, the apparent quantum efficiency remains as high as 14.47% even at 700 nm, being the highest one reported to date under similar conditions. Further analysis indicates Cu dopants induces abundant oxygen vacancies and introduces interband springboard into SrTiO3, which effectively extend the light response of SrTiO3 to the visible and NIR region and enhance the separation of charge carriers, being critical to the highly selective and efficient conversion of alcohols.

Macro- and mesoporous Cu2O/Cu3(OH)2(CO3)2 synthesized by supercritical CO2 as an efficient catalyst for alcohol oxidation

To develop high-performance catalyst for the selective oxidation of benzyl alcohols to benzyl aldehydes is of great importance. Here we synthesized a novel catalyst of cuprous oxide/basic cuprous carbonate (Cu2O/Cu3(OH)2(CO3)2) composite by supercritical CO2. The two components of Cu2O and Cu3(OH)2(CO3)2 have a synergistic catalytic effect to facilitate the oxidation of alcohol. Moreover, the catalyst has a hierarchically macro- and mesoporous structure, which favors the exposure of active sites, adsorption of reactants on the catalyst surface and mass transfer. Owing to these unique features, the as-synthesized Cu2O/Cu3(OH)2(CO3)2 shows high performance for the oxidation of benzyl alcohol to benzyl aldehyde at 75 °C under atmospheric O2.

Thiazolo[5,4‑d]thiazole linked conjugated microporous polymer photocatalysis for selective aerobic oxidation of amines

Recently, conjugated microporous polymers (CMPs) comprised of thiazolo[5,4-d]thiazole (TzTz) linkages have received much attention due to their excellent photoelectric properties. Herein, the polycondensation of dithiooxamide and benzyl aldehydes of C2, C3, and D2h symmetry afforded three TzTz-linked CMPs, namely TzTz-CMP-1, TzTz-CMP-2, and TzTz-CMP-3. Importantly, the porous and flexible characteristics of TzTz-linked CMPs enable the smooth selective aerobic oxidation of amines in ethanol (C2H5OH), a clean but redox-active solvent. All three TzTz-linked CMPs significantly surpass the benchmark mesoporous graphite carbonnitride (mpg-C3N4) photocatalyst. Intriguingly, TzTz-CMP-2 displays the best photocatalytic activity for the blue-light-mediated selective transformation of primary and secondary amines into imines. The conversions of amines were up to 90% with excellent selectivities for imines. This work highlights that CMPs with TzTz linkages may offer efficient photocatalytic selective transformations under genuinely ambient conditions.

Synthesis of Ni2+ cation modified TS-1 molecular sieve nanosheets as effective photocatalysts for alcohol oxidation and pollutant degradation

Improvement of the charge separation of titanosilicate molecular sieves is critical to their use as photocatalysts for oxidative organic transformations. In this work, MFI TS-1 molecular sieve nanosheets (TS-1 NS) were synthesized by a low-temperature hydrothermal method using a tailored diquaternary ammonium surfactant as the structure-directing agent. Introducing Ni2+ cations at the ion-exchange sites of the TS-1 NS framework significantly enhanced its photoactivity in aerobic alcohol oxidation. The optimized Ni cation-functionalized TS-1 NS (Ni/TS-1 NS) provide impressive photoactivity, with a benzyl alcohol (BA) conversion of 78.9% and benzyl aldehyde (BAD) selectivity of 98.8% using O2 as the only oxidant under full light irradiation; this BAD yield is approximately six times greater than that obtained for bulk TS-1, and is maintained for five runs. The excellent photoactivity of Ni/TS-1 NS is attributed to the significantly enlarged surface area of the two-dimensional morphology TS-1 NS, extra mesopores, and greatly improved charge separation. Compared with bulk TS-1, Ni/TS-1 NS has a much shorter charge transfer distance. The as-introduced Ni species could capture the photoelectrons to further improve the charge separation. This work opens the way to a class of highly selective, robust, and low-cost titanosilicate molecular sieve-based photocatalysts with industrial potential for selective oxidative transformations and pollutant degradation.