Journal of Chemical Sciences最新文献

This paper discusses synthesizing green, recyclable, heterogeneous nickel–chromium oxide (NiCr₂O₄) catalyst and its application in solvent-free, room-temperature Knoevenagel condensation reaction. Nickel–chromium oxides (Ni–Cr oxides) were prepared using the coprecipitation method in various proportions, such as 2:1, 1:1, and 1:2 ratios. The synthesized catalysts were characterized using X-ray diffraction, SEM-EDX, and BET-surface area analysis. The synthesized catalysts were employed as heterogeneous catalysts in the Knoevenagel condensation model reaction of 4-chlorobenzaldehyde and malononitrile under room temperature, solvent-free grinding reaction conditions, and the results were compared. This paper will discuss the most suitable catalyst and its possible mechanism.

A study on the interaction of non-metal oxide with water is very critical in order to understand the formation of acidic species and polyanions. It is very easy to understand the interaction of non-metal oxides with water by employing density functional theory (DFT). First-principles DFT is used to simulate the water cluster with three-dimensional continuums by defining a supercell with dimensions (13.49 times 12.696 times 3.174) ų. The geometry-optimized non-metal oxides are placed on the water clusters and allow for interactions. The geometry and stability of the chemical species formed are discussed and the results are correlated with the experiments. The phonon calculations are also carried out to confirm the chemical species formed and match well with the literature.

Graphical abstract

First-principles DFT is used to simulate the water cluster with three-dimensional continuums by defining a supercell with dimensions (13.49 times 12.696 times 3.174 ) ų. Interactions of water cluster with non-metal oxides furnished H₂CO₃, ({text{HSO}}_{3}^{-}), ({text{SO}}_{4}^{2-}), and ({text{NO}}_{3}^{-}) for CO₂, SO₂, SO₃, and ({{text{N}}_{2}text{O}}_{5}) respectively

The Sonogashira coupling reaction and hydration of nitriles were demonstrated using a facile catalytic system comprising a readily available cobalt salt and an environmentally friendly room-temperature ionic liquid, choline hydroxide (ChOH). The present system offers an alternative pathway for constructing C_sp–C_sp2 bonds through the alkynylation of aryl iodides in an aqueous environment, without the need for palladium- or copper-metal catalysts, phosphine ligands, or any external bases, albeit with some limited scope. Building upon the advantages and drawbacks of the present system employed in the Sonogashira coupling, we further extend its application to showcase the conversion of nitriles into amides, revealing the respective roles of ChOH and cobalt salt in the hydration of nitriles.

Graphic Abstract

The Sonogashira coupling and nitrile hydration were accomplished with cobalt salt and choline hydroxide (ChOH). Aryl iodides underwent alkynylation without external additives, albeit with limitations. Roles of ChOH and cobalt salt in nitrile hydration were also demonstrated.

Dinitrogen and dihydrogen ligated metal complexes [(L)_nM−H₂/N₂] have been known to chemists for nearly four decades. These species are captivating for their unusual bonding interactions between transition metal atoms and closed-shell diatomic molecules like H₂/N₂. Some of these complexes are part of the textbook, with emphasis given to their surprising stability, often without the formation of an electron-sharing M−H₂/N₂ bond. The nature of chemical bonding in these complexes is speculated due to M−H₂/N₂ bond distances and mode of binding (side-on or end-on). In the past, spectroscopic and other tools have studied the nature of the chemical bonds. We report on the energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) calculations to shed light on the deeper insight of the quantitative pairwise bonding interactions in previously isolated/reported (L)Co−N₂ and (L)Co−H₂ complexes [L = three P- and one E-donor ligand; E = Si, B; Co is either Co(I) or Co(0)]. A comparative EDA-NOCV analysis shows that N₂ is a better π-acceptor while, in contrast, H₂ is a superior σ-donor although both ligands (H₂, N₂) are σ-donor and σ/π-acceptor. The extent of backdonation from Co to H₂/N₂ also depends on E atoms of the chelating ligands (L). The overall intrinsic interaction energy of the Co−N₂ bond is significantly higher by 5–10 kcal/mol than that of the Co−H₂ bond. EDA-NOCV analyses have also studied two Fe−H₂ complexes.

Graphical abstract

An efficient multi-component protocol for synthesizing substituted 3-arylmethyl indoles derivatives through a three-component strategy using water: ethanol (H₂O:EtOH) at 45–50°C with good to excellent yields. The main advantages of this protocol are mild reaction conditions, easy workup, and recyclability of the catalyst for up to four catalytic cycles.

Graphical abstract

Synopsis: Synthesis of substituted 3-arylmethyl indoles by using efficient multi-component strategy in ethanol: water as a solvent system by using (Bu₃Sn)₂MoO₄ as a reusable catalyst at 45–50 °C with good to excellent yields. The catalyst is reusable in four catalytic cycles.

Abstract

Organic-inorganic hybrid perovskites like methylammonium lead iodide (MAPbI₃) have received extensive attention in solar energy conversion due to their superb optoelectronic properties. However, the serious charge recombination at the nanoscale domain and the lack of catalytic sites on the perovskite's surface seriously limit their photocatalytic hydrogen evolution activities. Taking MAPbI₃ as a typical example, we show that coupling amorphous molybdenum phosphide (MoP) cocatalyst with MAPbI₃ can significantly enhance the photocatalytic H₂ evolution performance of MAPbI₃. The MoP coupling can accelerate the electron extraction from MAPbI₃ and promote the hydrogen evolution reaction catalysis. Consequently, the photocatalytic hydrogen evolution activity of MoP/MAPbI₃ is ca. 97 times higher than that of bare MAPbI₃. Moreover, the MoP/MAPbI₃ exhibits good stability during cycling tests. This work demonstrates the possibility of employing amorphous MoP as a non-noble metal-based cocatalyst in a hybrid perovskite-based photocatalytic hydrogen production reaction.

Graphical abstract

Methylammonium lead iodide (MAPbI₃) loaded with molybdenum phosphide (MoP) cocatalyst demonstrates 97 times higher photocatalytic hydrogen evolution activity than bare MAPbI₃ from HI splitting reaction under visible light irradiation.

A series of 1-carbonyl-1H-indoles were prepared by 2-iodoanilines and calcium carbide in a one-pot reaction catalyzed by recyclable10% Pb/C, resulting in the corresponding substituted indoles in good yields. This protocol offers several advantages, including the utilization of sustainable, low-cost calcium carbide, an easy-to-handle acetylene source, and recyclable Pb/C catalysts.

Graphic abstract

The synthesis of a series of 1-carbonyl-1H-indoles were prepared by 2-iodoanilines and calcium carbide in a one-pot reaction catalyzed by 10% Pb/C, resulting in the corresponding substituted indoles in good yields. This protocol offers several advantages, including the utilization of sustainable, low-cost feedstock, an easy-to-handle acetylene source, and recyclable Pb/C catalysts.

Quinoline-based “turn-on” fluorescent probe was successfully synthesized using 5-amino quinoline and 2-(phenylselanyl)benzaldehyde. The probe was found to be selective for superoxide over other reactive oxygen species (ROS) and biothiols. The probe can detect superoxide in the presence of other ROS and biothiols. The detection limit of the probe for superoxide was found to be 37 nM with a Stokes shift of 150 nm. The probe quickly detects superoxide with a 21-fold increase in fluorescence intensity. The probe exhibited anticancer activity on HeLa cells that was comparable to the standard drug (Cisplatin).

Graphical abstract

Organoselenium based quinoline probe was developed. The probe was selective for superoxide with instant response and possess good anticancer activity.

The π-binding of iron tricarbonyl, Fe(CO)₃, tripod is known to effectively alter the stereoselectivity and torquoselectivity of electrocyclic ring opening (ERO) of cyclobutene and its derivatives by changing the mechanism. Representative examples of pseudopericyclic and also borderline pericyclic ERO reactions were chosen for the present study to establish the role of Fe(CO)₃ in manipulating the reactions. The parameters like nucleus-independent chemical shift (NICS), natural bond orbital (NBO) analysis, and topological parameters like ∇²ρ(r) (Laplacian) and ε (ellipticity) have revealed marked drifting of the reaction lying on the pseudopericyclic end to the borderline pericyclic end, which is due to Fe(CO)₃ binding.

Graphical abstract

Iron tricarbonyl alters the nature of pseudopericyclic reaction by making it borderline pericyclic. Activation barrier increases for pseudopericyclic case which is very low in the absence of Fe(CO)_3. No disconnection of orbitals is observed for pseudopericyclic system when complexed with Fe(CO)₃.

Three new palladium(II)-iminophosphine complexes, [Pd(L1)(Cl)₂] C1, [Pd(L2)(Cl)₂] C2 and [Pd(L3)(Cl)₂] C3 have been synthesized and successfully characterized by using ¹H-NMR, ¹³C-NMR, ³¹P-NMR, UV–Vis, FT-IR and magnetic susceptibility techniques. Catalytic activities of complexes towards Suzuki–Miyaura C–C coupling reactions between phenylboronic acid and several aryl halides were investigated under several reaction conditions (solvent, temperature, base, reaction time, and type of substrate). Under optimum conditions, achieving high yields of up to 99% was possible. When 1-bromo-4-nitrobenzene was used for complex C1, bromobenzene for complex C2, and bromobenzene for complex C3, product yields of 99, 99, and 98% were achieved, respectively.

Graphical abstract

Three new palladium complexes bearing iminophosphine ligands was synthesized and successfully characterized. Catalytic activities of the synthesized complexes were investigated on Suzuki–Myaura type coupling reaction between phenylboronic acid and several aryl halides. All complexes exhibited good catalytic activities on C–C coupling reactions up to 99% product formations under mild conditions.