Iridium(I)-salicylaldiminato-cyclooctadiene complexes used as catalysts for phenylborylation

Iridium(I) salicylaldiminato-cyclooctadiene complexes, Ir(-o-O-C₆H₄-CHN-R)(cod) (R = CH₂Ph (1), Ph (2); cod = 1,5-cyclooctadiene), have been prepared, characterized and used as catalysts for arylborylation via C-H activation. With 1 as a catalyst, isolated yields of up to 91% has been achieved for the borylation of benzene by bis(pinacolato)diboron in the presence of tetra-2-pyridinylpyrazine and an ionic liquid. The catalytic system could be recycled for at least three times without loss of activity.     

A new recyclable/reusable ionic liquid/LiCl system for Suzuki–Miyaura cross coupling reactions

Suzuki–Miyaura cross coupling reactions of aryl halides with aryl boronic acids were carried out in basic ionic liquids in the presence of lithium chloride as a promoter. The coupling reactions, carried out in the absence of base and ligand, proceed in good to excellent yields with easy product isolation and catalyst recycle.     

Ligand‐Induced Evolution of Intrinsic Fluorescence and Catalytic Activity from Cobalt Ferrite Nanoparticles

To develop CoFe₂O₄ as magneto‐fluorescent nanoparticles (NPs) for biomedical applications, it would be advantageous to identify any intrinsic fluorescence of this important magnetic material by simply adjusting the surface chemistry of the NPs themselves. Herein, we demonstrate that intrinsic multicolor fluorescence, covering the whole visible region, can be induced by facile functionalization of CoFe₂O₄ NPs with Na‐tartrate. Moreover, the functionalized CoFe₂O₄ NPs also show unprecedented catalytic efficiency in the degradation of both biologically and environmentally harmful dyes, pioneering the potential application of these NPs in therapeutics and wastewater treatment. Detailed investigation through various spectroscopic tools unveils the story behind the emergence of this unique optical property of CoFe₂O₄ NPs upon functionalization with tartrate ligands. We believe our developed multifunctional CoFe₂O₄ NPs hold great promise for advanced biomedical and technological applications.     

Solubility enhancement and QSPR correlations for polycyclic aromatic hydrocarbons complexation with α, β, and γ cyclodextrins

Through batch equilibrium experiments, hydroxypropyl substituted α, β, and γ cyclodextrin (CDs) were shown to greatly increase the apparent solubility of eight common polycyclic aromatic hydrocarbons (PAHs) in aqueous solutions. Equations based on the volume fraction of solution composed of water and CDs have been developed to determine guest phase distribution. Based on these equations, the results of this and similar studies for CD showed that a log–log relationship exists between the fraction of CD occupied with a guest organic compound and the aqueous solubility of those guests (rsq 0.980). Analysis of potential quantitative structure property relationship (QSPR) found strong correlations between structural properties of the guests (e.g. aqueous solubility, octanol/water partitioning coefficient, molar volume, molecular surface area, and polarizability) and water/CD partitioning coefficients, phase distribution of the PAH between water and CD phases, and the fraction of CD molecules occupied with a guest PAH. Noteworthy among these, is the inverse relationship between the log of the fraction of CD molecules occupied under saturated conditions and the ratio of the molar volume of the PAH to the volume of the CD cavities (rsq for α, β, and γ: 0.887–0.892). Comparisons of the three CDs shows that while the size of the guest compound reduces its propensity to enter into the CD cavity, the effect of the guest size is lessened as the width of the CD ring increases. Development of these QSPR correlations provides a means to predict and evaluate guest/CD interactions for homologous series of compounds.     

Synthesis of a novel class of steroidal tetrazolo[1,5-a]pyridines via intramolecular 1,3-dipolar cycloadditions

A facile synthesis of a novel class of steroidal A/B/D-ring annulated tetrazolo[1,5-a]pyridine derivatives has been accomplished via intramolecular 1,3-dipolar cycloaddition reaction of azide with nitrile in aprotic solvent. The synthesis of D-ring annulated tetrazolo[1,5-a]pyridine in alcohol showed incorporation of an alcohol molecule into the heterocyclic system.     

Demonstration of temperature resilient properties of 2D silicon carbide photonic crystal structures and cavity modes

In this paper, photonic crystal (PhC) based on two dimensional (2D) square and hexagonal lattice periodic arrays of Silicon Carbide (SiC) rods in air structure have been investigated using plane wave expansion (PWE) method. The PhC designs have been optimized for telecommunication wavelength (λ = 1.55 μm) by varying the radius of the rods and lattice constant. The result obtained shows that a photonic band gap (PBG) exists for TE-mode propagation. First, the effect of temperature on the width of the photonic band gap in the 2D SiC PhC structure has been investigated and compared with Silicon (Si) PhC. Further, a cavity has been created in the proposed SiC PhC and carried out temperature resiliency study of the defect modes. The dispersion relation for the TE mode of a point defect A1 cavity for both SiC and Si PhC has been plotted. Quality factor (Q) for both these structures have been calculated using finite difference time domain (FDTD) method and found a maximum Q value of 224 for SiC and 213 for Si PhC cavity structures. These analyses are important for fabricating novel PhC cavity designs that may find application in temperature resilient devices.     

Synthesis and conformational studies of novel cyclic peptides constrained into a 3 10 helical structure by a heterochiral D-pro-L-pro dipeptide template

An acyclic tripeptide based on a heterochiral D-pro-L-pro template shows a propensity to exist as a 3(10) helical conformation and can be cyclized, via ring-closing metathesis, to the corresponding cyclic tetrapeptides without disrupting the helical conformations in CDCl(3) as well as in DMSO-d(6) solutions. The detailed conformational studies were carried out by using NMR spectroscopy, X-ray crystallography, molecular dynamic simulations, and circular dichroism spectroscopy.     

Synthesis and Antifungal Activities of Some New 5,7‐Disubstituted[1,2,4]Triazolo[1,5‐a]Pyrimidin‐6‐one Derivatives

Synthesis of a new series of [1,2,4]triazolo[1,5‐a]pyrimidin‐6‐one by [4 + 2]cycloaddition reaction of 3‐benzylidineamino[1,2,4]triazole with monophenyl ketene and diphenyl ketene generated in situ from phenylacetyl chloride and diphenylacetyl chloride in the presence of triethylamine is described. The newly synthesized compounds were also tested for antifungal activities against Rhizoctonia solani and Trichoderma sp.     

(Cyclopentadienone)iron Complexes: Synthesis,Mechanism and Applications in Organic Synthesis

(Cyclopentadienone)iron tricarbonyl complexes are catalytically active, inexpensive, easily accessible and air-stable that are extensively studied as an active pre-catalyst in homogeneous catalysis. Its versatile catalytic activity arises exclusively due to the presence of a non-innocent ligand, which can trigger its unique redox properties effectively. These complexes have been employed widely in (transfer)hydrogenation (e. g., reduction of polar multiple bonds, Oppenauer-type oxidation of alcohols), C−C and C−N bond formation (e. g., reductive aminations, α-alkylation of ketones) and other synthetic transformations. In this review, we discuss the remarkable advancement of its various synthetic applications along with synthesis and mechanistic studies, until February 2021.     

Partition identities arising from Ramanujan’s formulas for multipliers

We find new partition identities arising from Ramanujan’s formulas of multipliers. Several of the identities are for overpartitions, overpartition pairs, and \(\ell \)-regular partitions.