Recent progress on CO2 separation membranes.

Presently, excessive carbon dioxide emissions represent a critical environmental challenge. Thus, urgent efforts are required to develop environmentally friendly and low-energy technologies for carbon dioxide treatment. In this case, membrane separation technology stands out as a promising avenue for CO2 separation, with selective membrane materials of high permeability playing a pivotal role in this process. Herein, we categorize CO2 separation membranes into three groups: inorganic membranes, organic membranes, and emerging membranes. Moreover, representative high-performance membranes are introduced and their synthesis methods, gas separation performances, and applications are examined. Furthermore, a brief analysis of the challenges encountered by carbon dioxide separation membrane materials is provided together with a discussion on the future research direction. It is expected that this review will provide some potential insights and guidance for the future development of CO2 separation membranes, which can promote their development.

Resource Utilization of Waste Cooking Oil Catalyzed by Na2CO3/ZSM-5.

A catalyst with a simple synthetic process and good catalytic performance was prepared using Na2CO3 as the active component and ZSM-5 as the carrier for the resource utilization of waste cooking oil. The structure of Na2CO3/ZSM-5 was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy, and the effects of parameters such as Na2CO3 loading, catalyst percentage, and reaction time on the yield of fatty acid methyl esters were investigated. The results showed that the conversion of waste cooking oil to fatty acid methyl esters yielded up to 96.89% when the Na2CO3 loading was 35%, the reaction temperature was 65 °C, the reaction time was 2 h, and the catalyst percentage was 1 wt %. The Na2CO3/ZSM-5 catalyst could be used to replace H2SO4 or NaOCH3 in the industrial treatment of waste cooking oil for its resource utilization.

Optimization of preparation conditions of medium and highly substituted carboxymethyl inulin through response surface methodology.

This article introduces the synthesis optimization of carboxymethyl inulin using response surface methodology. The important factors affecting the degree of substitution (DS) were determined by Plackett-Burman design, including sodium hydroxide concentration, monochloroacetic concentration, and etherification temperature. Further optimization was conducted using the Box-Behnken response surface design. The coefficient of determination (R2) of the response surface model was 0.9827, and the adjusted R2 value was 0.9516, which proved the significance of the model. The optimized results of the predicted response showed that the molar ratios of sodium hydroxide to monochloroacetic acid and fructose to furan were 3.67 and 2.21, respectively. The maximum DS of 1.67 was obtained at 30 °C alkalization for 30 min and 50.30 °C etherification for 4 h, and the reaction efficiency (RE) reached 76.01 %. Under the optimized conditions, the Experimental DS was 1.68, suggesting that the experimental and predicted values of DS were in good agreement. The characterization results confirmed the synthesis of CMI. In this work, we have provided an effective method for the preparation of moderately to highly substituted CMI in 95 % ethanol.

Azide-free cyclization reaction access to 4-aryl-NH-1,2,3-triazoles: P-toluenesulfonyl hydrazide and sulfamic acid as nitrogen sources.

An iodine-mediated cyclization has been developed to 4-aryl-NH-1,2,3-triazoles, with p-toluenesulfonyl hydrazide and sulfamic acid used as nitrogen sources. Sulfamic acid plays a crucial role in this reaction by both acting as a substrate and providing an acidic environment. This reaction offers a metal- and azide-free strategy to access NH-1,2,3-triazoles.

A novel turn-on fluorescent probe for detection of pH in extremely acidic environment and its application.

A water-soluble turn-on fluorescent probe PNAP for pH has been designed and synthesized. PNAP was consist of pyrene as fluorophore and morpholine as receptor. Owing to the photoinduced electron transfer (PET) effect, the fluorescence of PNAP was quenched, while PNAP exhibited a remarkable "turn-on" fluorescence with the increase of acidity. Notably for its pKa of 2.15, PNAP was one of the pH fluorescent probes used in extremely acidic environments. Furthermore, PNAP also displayed good repeatability, strong anti-ion interference ability, high sensitivity and selectivity toward pH. In addition, PNAP has been successfully applied to the test strips and monitor the pH of environment water samples and realistic samples, showing its good promising prospect.

Tandem Ene/[4 + 2] Cycloaddition Reaction for the Synthesis of 9-Benzylphenanthrenes from Arynes and α-(Bromomethyl)styrenes.

A tandem reaction for the synthesis of phenanthrenes from arynes and α-(bromomethyl)styrenes is reported. The transformation proceeds via an ene reaction of α-(bromomethyl)styrenes with arynes, followed by a [4 + 2] cycloaddition reaction. The reaction generates 9-benzylphenanthrene derivatives in moderate to excellent yields.

Copper/TEMPO-Promoted Denitrogenation/Oxidation Reaction for Synthesis of Primary α-Ketoamides Using α-Azido Ketones.

A copper(II)-promoted denitrogenation/oxidation reaction for the preparation of primary α-ketoamides was developed using α-azido ketones as a substrate and TEMPO as an oxidant. α-Azido ketones were denitrogenated in situ to form an imino ketone intermediate, which underwent a radical addition process and radical migration to form α-ketoamides. It is worth noting that the imino ketone intermediate is the key to this reaction.

Intramolecular redox cyclization reaction access to cinnolines from 2-nitrobenzyl alcohol and benzylamine via intermediate 2-nitrosobenzaldehyde.

A transition-metal-free intramolecular redox cyclization reaction for the synthesis of cinnolines has been developed from 2-nitrobenzyl alcohol and benzylamine. Mechanistic investigations disclosed the involvement of a key intramolecular redox reaction, followed by condensation, azo isomerization to hydrazone, cyclization, and aromatization to form the desired products. Notably, the formation of intermediate 2-nitrosobenzaldehyde and (E)-2-(2-benzylidenehydrazineyl) benzaldehyde plays an important role in this transformation.

Rh(III)-Catalyzed Tandem Reaction Access to (Quinazolin-2-yl)methanone Derivatives from 2,1-Benzisoxazoles and α-Azido Ketones.

A Rh(III)-catalyzed tandem reaction for the synthesis of (quinazolin-2-yl)methanone derivatives has been explored from 2,1-benzisoxazoles and α-azido ketones. The transformation involves Rh(III)-catalyzed denitrogenation of α-azido ketones, aza-[4 + 2] cycloaddition, ring opening, and dehydration aromatization processes. Notably, the aza-[4 + 2] cycloaddition of an imine rhodium complex intermediate with 2,1-benzisoxazoles is the key to this reaction.

Recent progress in cadmium fluorescent and colorimetric probes.

Cadmium is a heavy metal which exists widely in industrial and agricultural production and can induce a variety of diseases in organisms. Therefore, its detection is of great significance in the fields of biology, environment and medicine. Fluorescent probe has been a powerful tool for cadmium detection because of its convenience, sensitivity, and bioimaging capability. In this paper, we reviewed 98 literatures on cadmium fluorescent sensors reported from 2017 to 2021, classified them according to different fluorophores, elaborated the probe design, application characteristics and recognition mode, summarized and prospected the development of cadmium fluorescent and colorimetric probes. We hope to provide some help for researchers to design cadmium fluorescent probes with higher selectivity, sensitivity and practicability.

Tunable Luminescent Properties of Tricyanoosmium Nitrido Complexes Bearing a Chelating O

We have recently reported a strongly luminescent osmium(VI) nitrido complex [OsVI(N)(NO2-L)(CN)3]- [HNO2-L = 2-(2-hydroxy-5-nitrophenyl)benzoxazole]. The excited state of this complex readily activates the strong C-H bonds of alkanes and arenes (Commun. Chem. 2019, 2, 40). In this work, we attempted to tune the excited-state properties of this complex by introducing various substituents on the bidentate L ligand. The series of nitrido complexes were characterized by IR, UV/vis, 1H NMR, and electrospray ionization mass spectrometry. The molecular structures of five of the nitrido compounds have been determined by X-ray crystallography. The photophysical and electrochemical properties of these complexes have been investigated. The luminescence of these nitrido complexes in the solid state, in a CH2Cl2 solution, and in a CH2Cl2 solid matrix at 77 K glassy medium clearly shows that these emissions are due to 3LML'CT [L ligand to Os≡N] phosphorescence. The presence of strongly electron-withdrawing substituents in these complexes enhances the LML'CT emission. Our result demonstrates that the excited-state properties of this novel class of luminescent osmium(VI) nitrido complexes can be fine-tuned by introducing various substituents on the bidentate L ligand.

Metal-Free Cascade [4 + 1] Cyclization Access to 4-Aryl-NH-1,2,3-triazoles from N-Tosylhydrazones and Sodium Azide.

A molecular iodine-mediated coupling cyclization reaction for the synthesis of 4-aryl-NH-1,2,3-triazoles has been developed from N-tosylhydrazones and sodium azide. This metal-free cascade [4 + 1] cyclization reaction could rapidly synthesize valuable compounds via a sequential C-N and N-N bond formation. Mechanistic studies demostrate that the nitrogen atoms of the 1,2,3-triazoles are not entirely from sodium azide.

A cascade oxidation/[4 + 1] annulation of sulfonium salts for synthesis of polyfunctional furans: DMSO as one carbon source.

A novel DMSO-involved cascade reaction of stabilized sulfonium salts has been established for direct construction of polyfunctional furans. This one-pot sequential reaction involving in situ generated α-methylene sulfonium salts was followed by [4 + 1] annulation with sulfur ylides. Notably, DMSO plays a very important role in this transformation, not only as a solvent but also as one carbon source.

TFA-Mediated DMSO-Participant Sequential Oxidation/1,3-Dipolar Cycloaddition Cascade of Pyridinium Ylides for the Assembly of Indolizines.

A trifluoroacetic acid (TFA)-mediated cascade oxidation/1,3-dipolar cycloaddition reaction of stabilized pyridinium salts with dimethyl sulfoxide (DMSO) has been developed in the presence of K2S2O8 and trimethylethylenediamine (TMEDA). In this transition-metal-free reaction, DMSO acts as a one-carbon source, thus providing a convenient method for the efficient and direct synthesis of various indolizine derivatives.

Molecular iodine-mediated formal [2+1+1+1] cycloaddition access to pyrrolo[2,1-a]isoquinolines with DMSO as the methylene source.

A molecular iodine-mediated formal [2+1+1+1] cycloaddition for the efficient synthesis of pyrrolo[2,1-a]isoquinolines from acetophenones, 1,2,3,4-tetrahydroisoquinoline (THIQ) and DMSO has been developed. Mechanistic studies revealed that DMSO served as the methylene source, and this novel protocol involves intermolecular cycloaddition of two in situ generated intermediates that enable efficient formation of one C-N bond and three C-C bonds via multiple sequential C-H functionalizations.

Sequential σ-Bond Insertion/Benzannulation Involving Arynes: Selective Synthesis of Polysubstituted Naphthalenes.

An interesting σ-bond insertion/benzannulation reaction for the synthesis of polysubstituted naphthalene derivatives has been developed from readily accessible ketones, arynes, and alkynoates. This practical and transition-metal-free method provides a novel route to diverse naphthalenes through a substrate-controlled rearrangement reaction with the cleavage of C-C bonds.

Acid-Mediated Intermolecular [3 + 2] Cycloaddition toward Pyrrolo[2,1-a]isoquinolines: Total Synthesis of the Lamellarin Core and Lamellarin G Trimethyl Ether.

A novel one-pot reaction has been developed for the efficient synthesis of pyrrolo[2,1-a]isoquinolines and 1-dearyllamellarin core from (E)-(2-nitrovinyl)benzenes and azomethine ylides generated in situ. This strategy provides a concise total synthesis of the lamellarin core and lamellarin G trimethyl ether using electrophilic substitution and palladium-catalyzed Suzuki-Miyaura cross-coupling reactions.

Transition-Metal-Free Coupling Annulation of Arynes with Ketones and Alkynoates: Assembly of Functionalized Naphthalenes.

A transition-metal-free coupling annulation reaction of arynes, ketones, and alkynoates has been demonstrated. Using this formal [2 + 2 + 2] cycloaddition reaction, a wide variety of naphthalene derivatives were conveniently constructed in one pot with high efficiency. In addition, this novel and valid annulation has been successfully applied to the synthesis of 1-phenanthrenol derivatives.

Acid-Mediated N-H/α,ß-C(sp(3))-H Trifunctionalization of Pyrrolidine: Intermolecular [3 + 2] Cycloaddition for the Construction of 2,3-Dihydro-1H-Pyrrolizine Derivatives.

A one-pot acid-mediated reaction has been developed for the N-H/α,ß-C(sp(3))-H trifunctionalization of pyrrolidine without any metallic reagents or external oxidants. This reaction involves the intermolecular [3 + 2] cycloaddition of in situ-generated azomethine ylides with acrylic esters to provide facile access to 2,3-dihydro-1H-pyrrolizine derivatives in high yields under mild conditions.

Acid-Catalyzed Multicomponent Tandem Cyclizations: Access to Polyfunctional Dihydroindolizino[8,7-b]indoles.

An acid-catalyzed multicomponent tandem cyclization protocol has been developed for the synthesis of polyfunctional dihydroindolizino[8,7-b]indoles from simple and readily available arylglyoxal monohydrates, tryptamines, and trans-ß-nitrostyrenes or malononitrile. This reaction represents a highly efficient and convenient methodology for the synthesis of diversely substituted heteropolycyclic scaffolds under mild, metal-free conditions.