Selective Oxidation Of Sulfides Research Articles

Photoactive Covalent Organic Frameworks for Catalyzing Organic Reactions.

Because of their large surface areas, long-range order, π-π stacking interactions and hierarchically integrated building blocks, covalent organic frameworks (COFs) have attracted increasing attention. Recently, COFs have been regarded as promising heterogeneous photocatalysts, owing to their remarkable light-harvesting and energy transition capabilities. The research progress of COFs in photocatalytic organic synthesis is summarized, such as preparation of imines through the oxidation of amines, selective oxidation of sulfides, oxidative hydroxylation of arylboronic acids, C-H bond activation, cyclization, asymmetric organic synthesis and so on. Finally, a perspective of the present challenges of photoactive COFs in organic transformations is given.

Spatial Band Separation in a Surface Doped Heterolayered Structure for Realizing Efficient Singlet Oxygen Generation.

Singlet oxygen (1 O2 ) with electrical neutrality and long lifetime holds great promise in producing high-added-value chemicals via a selective oxidation reaction. However, photocatalytic 1 O2 generation via the charge-transfer mechanism still suffers from low efficiency due to the mismatched redox capacities and low concentration of photogenerated carriers in confined systems. Herein, by taking bismuth oxysilicate (Bi2 O2 SiO3 ) with alternating heterogeneous layered structure as a model, it is shown that iodine doping can facilitate the spatial redistributions of bands on alternated [Bi2 O2 ] and [SiO3 ] layers, which can promote the separation and transfer of photogenerated charge carriers. Meanwhile, the band positions of Bi2 O2 SiO3 are optimized to match the redox potential of 1 O2 generation. Benefiting from these features, iodine-doped Bi2 O2 SiO3 exhibits efficient 1 O2 generation with respect to its pristine counterpart, leading to promoted performance in the selective sulfide oxidation reaction. A new strategy is offered here for optimizing charge-transfer-mediated 1 O2 generation.

Introduction of Ni into mesoporous MCM-41: A new recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles and the selective oxidation of sulfides

Introduction of Ni into mesoporous MCM-41: A new recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles and the selective oxidation of sulfides

Solvent-Induced Isomeric Cu13 Nanoclusters: Chlorine to Copper Charge Transfer Boosting Molecular Oxygen Activation in Sulfide Selective Oxidation

Isomers with minimal structural dissimilarities are promising research objects to obtain a comprehensive understanding of structure-property relationships; however, comparability of isomeric structures is a prerequisite. Herein, two quasi-structurally isomeric 13-nuclei copper nanoclusters (Cu NCs) (Cu13a and Cu13b) containing highly similar Cu13 kernels and different arrangements of peripheral ligands were obtained using a solvent-induced strategy. The exotic chloride ion is shown to play a prominent role in inducing the selective formation of two quasi-isomers, where the comparative study to establish a structure-property relationship was realized. Due to the charge transition from chlorine to the copper core (X(Cl)M(Cu)CT), the molecular oxygen activation of Cu13a showed higher singlet oxygen (1O2) and lower superoxide radical (O2•-) yields compared to those of Cu13b, which gives it better catalytic selectivity for the 1O2 involved selective oxidation of sulfides. The present work not only offers a controllable strategy for the rational design and synthesis of quasi-structurally isomeric Cu NCs but also provides a pathway to boost catalytic selectivity by a halogen to metal core charge transition.

Selective oxidation of sulfides and synthesis of 5-substituted 1H-tetrazoles on Ce (III) immobilized CoFe2O4 as a magnetically separable, highly active, and reusable nanocatalyst

Selective oxidation of sulfides and synthesis of 5-substituted 1H-tetrazoles on Ce (III) immobilized CoFe2O4 as a magnetically separable, highly active, and reusable nanocatalyst

Atropisomer-based construction of a new perylene diimide macrocycle as visible-light photocatalyst for selective sulfide oxidation

By using a perylene diimine (PDI) syn -atropisomer as highly preorganized precursor, we successfully constructed a visible-light-active organic macrocycle PDI-M . The formation of macrocyclic structure effectively avoids self-aggregation of PDI cores and enhances the absorption in visible region. As a photocatalyst, PDI-M exhibits excellent activity on aerobic selective oxidation of sulfide into sulfoxide under visible light irradiation at room temperature. Mechanism studies show that both superoxide and singlet oxygen act as reactive oxygen species. This work provides a typical case toward the maximum utilization of photosensitive groups under mild conditions. A visible-light-active organic macrocycle was successfully constructed from a perylene diimide syn -atropisomer as highly preorganized precursor. As a photocatalyst, the macrocycle exhibits excellent activity on aerobic oxidation of sulfide into sulfoxide under visible light irradiation at room temperature.

A Bimetallic Ag/Ti‐Based Coordination Polymer as a Catalyst for Electrocatalytic CO2 Reduction and Selective Sulfide Oxidation

AbstractThe first example of heterometallic Ag/Ti bimetallic‐based coordination polymer was synthesized using salicylic acid as the ligand. The uniform Ag/Ti−O rod array has efficient electrocatalytic CO2 reduction activity with a Faradaic efficiency (FE) of 90.3 % at −0.88 V (vs RHE) and a maximum TOF of 658 h−1 at −1.08 V. The chemical catalytic property of the Ag/Ti−O rod was also studied, and the results showed that the Ag/Ti−O rod has good catalytic performance for selective oxidation of sulfide to sulfoxide.

Donor-acceptor type two-dimensional porphyrin-based covalent organic framework for visible-light-driven heterogeneous photocatalysis

• New metal-free acceptor-donor type COFs were synthesized. • As-synthesized COFs exhibited excellent photocatalytic properties. • The simulation of energy levels reveals the mechanism of electron transfer. • The COFs have excellent recyclability. Two-dimensional covalent organic frameworks (2D-COFs) with permanent porosity, structural controllability, and excellent stability, are receiving ongoing attention in metal-free heterogeneous photocatalysis of organic conversions. In order to construct high optical performance COFs for selective organic transformation, herein, 2D porphyrin-based donor-acceptor (D-A) type COFs were prepared by adjusting the morphology and structure. The as-synthesized COFs facilitate charge transfer and separation of photogenerated electron-hole pairs, efficaciously producing superoxide radical anions as mediates for selective oxidation of sulfides (97% conversion and 99% of selectivity) and reductive dehalogenation of 2-bromoacetophenone (up to 99% conversion and 82% of yield). The COFs have excellent stability and recyclability, demonstrating that the 2D D-A type COFs are attractive as heterogeneous photocatalyst for visible light driven organics transformation.

Recent Advances in Catalytic Oxidation of Organic Sulfides: Applications of Metal-Ionic Liquid Catalytic Systems.

Catalytic oxidation of organic sulfides is of considerable significance in industrial chemistry and fuel industry. Therefore, numerous methods have been developed for the oxidation. Metal-containing ionic liquid-based catalysts can catalyze the selective oxidation reactions and are highly used in chemical processes, which have also been used as effective solvents, reaction media, extractants, and catalysts for the oxidation of organic sulfides including oxidative desulfurization of fuel oil. Recently, much attention is being drawn to the preparation of heterogenous catalysts based on the immobilization of metal- or nonmetal-containing ILs on diverse solid supports, which can be easily separated after the completion reaction and recycled. Therefore, there is still an increasing interest in developing new and efficient catalytic procedures for the oxidation of organic sulfides. In this review, we have outlined the recent advances in catalytic oxidation of organic sulfides including oxidative desulfurization of fuel oil. The versatilities and adaptabilities of metal–ionic liquid catalytic systems in the selective oxidation of sulfides are considered a powerful research field in these transformations.

Synthesis, crystal structure, spectral characterization, theoretical studies, and investigation of catalytic activity in selective oxidation of sulfides by oxo-peroxo tungsten(VI) Schiff base complex

A novel oxo–peroxo tungsten(VI) Schiff base complex, [WO(O2)L(CH3OH)], a homogeneous catalyst for sulfoxidation was synthesized by treating WO3 in the presence of H2O2 with a dibasic tridentate (ONO) Schiff base ligand. The complex was characterized by FT–IR, 1H NMR, and 13C NMR spectroscopy. Moreover, the structure of the crystalline tungsten(VI) complex was further investigated by single crystal X-ray diffraction analysis (SC-XRD). The crystal structure analysis revealed that the complex is hepta-coordinated, and metal ion is surrounded by ONO set of the coordinated doubly deprotonated ligand to adopt a distorted pentagonal–bipyramidal geometry. The theoratical calculations of the geometrical parameters, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), and natural bond orbital (NBO) analysis of the synthesized compounds utilizing DFT at the B3LYP level of theory at the Def2-TZVP basis set revealed that the predicted data match the experimental results. The main purpose of the current study is to employ the synthesized W complex for its homogeneous catalytic effectiveness for the oxidation of aryl and alkyl sulfides in ethanol by using 30% aqueous H2O2.

Pyridylidene Amide Ru Complex for Selective Oxidation in Organic Synthesis.

The ruthenium(II) bis(PYA) complex 1 (PYA = p-pyridylidene amide) is a powerful catalyst for the oxidation of sulfides to sulfones, of alkenes to carbonyl compounds, and of terminal alkynes to carboxylic acids by using NaIO4 as the terminal oxidant. The catalytic system shows a broad functional group tolerance and rate differences between alkyne and sulfide oxidation that are sufficiently large to effectively achieve selective sulfide oxidation with exquisite selectivity.

Self-Assembly of Chiral Ferrocene-Functionalized Polyoxotitanium Clusters for Photocatalytic Selective Sulfide Oxidation.

Here, we systematically studied the self-assembly behavior of chiral polyoxytitanium clusters for the first time. Through the cooperative assembly of ferrocenecarboxylic acid and ketoxime ligands, we successfully incorporated the planar chirality of ferrocene (Fc) into the layered {Ti5} building blocks. The resulting {Ti5Fc} clusters can be used as structural units to assemble into large ordered structures in various ways; either a pair of {Ti5Fc} enantiomers are bridged by organic adhesive to form sandwich structures or two homochiral {Ti5Fc} units participate in the assembly to form the large clusters. Depending on the assembly modes, the chirality of {Ti5Fc} can be transferred to large nanoclusters or disappear to form mesostructures. The difference of the assembly modes between the {Ti5Fc} units can also tune the photoelectric activity of the resulting clusters, which has been verified by using {Ti10Fc-6/7} as catalysts for photocatalytic selective sulfide oxidation. This work not only is an important breakthrough in the study of the self-assembly of chiral nanoclusters but also provides an important reference for understanding of chiral transfer on the nanoscale.

2D Ti-based metal–organic framework photocatalysis for red light-driven selective aerobic oxidation of sulfides

Ti-based metal-organic frameworks (MOFs) consisting of organic linkers and Ti-oxo clusters have tremendous proneness in visible light photocatalysis. Here, two-dimensional (2D) Ti-based porphyrin MOF (PMOF (Ti)) and bulk PMOF (Ti) were synthesized and fully characterized. Consequently, the porphyrin linker imparts broad absorption of visible light and the appropriate reduction potential of Ti‐oxo clusters can activate O2 to superoxide (O2•–). The 2D PMOF (Ti) exhibits more satisfying results for the red light-driven selective oxidation of sulfides with O2 than bulk PMOF (Ti). In addition, 2D PMOF (Ti) is highly robust which could be recycled 8 times without any loss of photocatalytic activity. Mechanistic investigations reveal that O2•– is the crucial reactive oxygen species (ROS) in forming sulfoxides with high selectivities. This work highlights that 2D MOFs could have a great potential in selective photocatalytic transformations of organic molecules.

Acetylene/Vinylene-Bridged π-Conjugated Covalent Triazine Polymers for Photocatalytic Aerobic Oxidation Reactions under Visible Light Irradiation.

Solar-driven photocatalytic chemical transformation provides a sustainable strategy to produce valuable feedstock, but designing photocatalysts with high efficiency remains challenging. Herein, two acetylene- or vinylene-bridged π-conjugated covalent triazine polymers, A-CTP-DPA and V-CTP-DPE, were successfully fabricated toward metal-free photocatalytic oxidation under visible light irradiation. Compared to the one without acetylene or vinylene bridge, both resulting polymers exhibited superior activity in photocatalytic selective oxidation of sulfides and oxidative coupling of amines; in particular, A-CTP-DPA delivered an optimal photocatalytic performance. The superior activity was attributed to the broadened spectral response range, effective separation, rapid transportation of photogenerated charge carriers, and abundant active sites for photogenerated electrons due to the existence of the acetylene bridge in the framework. This work highlights the potential of acetylene and vinylene bridges in tuning catalytic efficiency of organic semiconductors, providing a guideline for the design of efficient photocatalysts.

Scalable selective electrochemical oxidation of sulfides to sulfoxides

An electrochemical protocol for the selective oxidation of sulfides to sulfoxides has been developed in which NaCl plays a dual role: (1) as an electrolyte for the electrochemical transformations and (2) as a redox mediator to avoid oxidation of sensitive functional groups.

A two-dimensional Bi-based porphyrin metal–organic framework photocatalyst for white light-driven selective oxidation of sulfides

A single crystal of a Bi-based porphyrin metal–organic framework was synthesized by a hydrothermal method. It exhibited significant photocatalytic activity for the selective oxidation of sulfides, maintaining high activity after 10 catalytic cycles.

A highly efficient heterogeneous catalyst for selective oxidation of sulfides derived from an open-framework copper borovanadate containing a unique crown-shaped anion.

A novel 3D open-framework copper borovanadate with a unique crown-shaped anion [(VIVO)8(VVO)4B32O64(OH)8]12- and the largest ratio of Cu2+/borovanadate anions (6/1) has been successfully synthesized and systematically studied. The compound not only possesses high stability in a wide pH range of 3.2-10.8 (DMF solution), but also exhibits excellent catalytic activities for selective oxidation of sulfides.

Molecular engineering of covalent triazine frameworks for highly enhanced photocatalytic aerobic oxidation of sulfides

By integrating various electron-donating units into CTFs, their photophysical and photochemical properties can be facilely modulated to achieve an enhanced performance for photocatalytic selective oxidation of sulfides to sulfoxides.

Olefin-linked covalent organic framework nanotubes based on triazine for selective oxidation of sulfides with O2 powered by blue light

Imine, hydrazone, and olefin-linked covalent organic frameworks (COFs) prosper in visible light photocatalysis. Markedly, the olefin-linked COFs are usually superior in transfer of π-conjugated electron powered by visible light albeit their construction is more challenging. Herein, two olefin-linked COFs were forged between 2,4,6-trimethyl-1,3,5-triazine (TMT) and 2,4,6-tris(4-formyl-phenyl)-1,3,5-triazine (TFPT) or 1,3,5-tris(4-formyl-phenyl)-benzene (TFPB) to afford TTO-COF or TBO-COF, respectively. Both of the olefin-linked COFs based on triazine are of good crystallinity, uniform micropores, and high specific surface areas, but of different morphologies, namely nanotubes and nanosheets. Compared to TBO-COF, TTO-COF nanotubes were constructed with two building blocks based on triazine, which could not only improve the planarity of a single layer but also cause closer stacking of layers in between. Therefore, TTO-COF nanotubes exhibit better photocatalytic performance and stability in the selective oxidation of organic sulfides into corresponding sulfoxides with O2 powered by blue light. Mechanistic investigation evidence the formation of desired sulfoxides was shaped by both electron and energy transfer pathways over TTO-COF nanotubes. This work underlines the ascendancy of olefin-linked COFs inasmuch as they provide an effective platform to construct efficient and durable photocatalysts based on adaptable organic building blocks.

Fabrication of La (III) supported on CoFe2O4 MNPs: a novel and efficient heterogeneous catalyst for selective oxidation of sulfides and synthesis of symmetrical disulfides

Fabrication of La (III) supported on CoFe2O4 MNPs: a novel and efficient heterogeneous catalyst for selective oxidation of sulfides and synthesis of symmetrical disulfides