Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Host-guest systems that function under physiologically relevant conditions possess considerable potential to contribute to biological and biomedical applications. We previously developed a 4-aminoquinoline (4-AQ)-based tweezer-type host molecule that forms stable complexes with heme and protoporphyrin IX (PPIX) in DMSO/HEPES buffer (pH 7.4) (2:3, v/v), respectively. However, the binding study including the determination of association constants of the 4-AQ-based tweezer-type host molecule under more physiologically relevant conditions was not possible although it was one of the most important parts of our studies. In this paper, we report a new host-guest system based on the 4-AQ-based tweezer-type host molecule and chlorin e6 (Ce6). The 4-AQ-based tweezer-type host molecule formed a highly stable host-guest complex not only in DMSO/HEPES buffer (pH 7.4) (2:3, v/v) but also in more physiologically relevant conditions (HEPES buffer or phosphate-buffered saline, pH 7.4, 1.0% (v/v) DMSO). Their association constants for a 1:1 complex were determined to be 10⁶–10⁷ M^− 1 under the investigated aqueous media. These results were first obtained using Ce6 as the guest molecule instead of heme and PPIX because Ce6 at low concentrations preferentially exists in a monomeric form in water at neutral pH. The study findings provide useful information for the future molecular design, evaluation, and applications of host-guest systems between tweezer-type host molecules and their appropriate guest molecules in aqueous media.

Herein, the electrochemical, luminescent and potential biological properties of a newly synthesized series of macrocyclic complexes of samarium(III) metal ion are described. Macrocycles, Schiff bases and their complexes with metals display several structural and electronic features that allow their vast applications in diverse research fields especially, in medicinal science. The synthesis of luminescent and electrically active complexes containing (1E,15Z)-3,4,6,7,9,10,12,13,14,16-decahydro-2H-[1, 4, 7]trioxa [11, 14]diaza-cycloheptadecino[12, 13-b]indole scaffold is done via template route using isatin or its derivatives i.e., 5-chloroisatin and 5-bromoisatin, and 1,13-diamino-4,7,10-trioxatri-dacane ligand precursors in the presence of Sm(III)nitrate hexa-hydrate salt. The synthesized complexes are found thermally stable up to ~ 230^oC and after that started to decompose. The structural characterization is done by the ¹H-NMR, electrospray ionization mass, Fourier transform, and ultraviolet-visible spectroscopy. The proposed structure of these complexes was well-matched by the data. Crystalline nature of the reported complexes is confirmed by the existence of sharp narrow peaks in the X-ray diffraction (XRD). The complexes also found electrically active as the cyclic voltammetry conductivity measured by using DMSO solvent. The complexes displayed characteristic luminescence peaks of Sm(III) at ~ 563, ~602 & ~644 nm assigned to ⁴G_5/2 →⁶H_5/2, ⁴G_5/2→ ⁶H_7/2, ⁴G_5/2→ ⁶H_9/2 transitions respectively. The biological studies results indicate the remarkable potential of these complexes as antimicrobial and antioxidant agent which may lead the use of these complexes in pharmaceutical field.

Silver nanoparticles (AgNPs) are increasingly valued for their diverse applications, but traditional preparation methods often involve toxic chemicals, necessitating environmentally friendly alternatives. This study explores a sustainable alternative: the green synthesis of AgNPs using brewed coffee grounds (BCG). BCG, a readily available agricultural byproduct rich in phenolic compounds, particularly chlorogenic acid, acts as a reducing and capping agent, facilitating the sustainable and efficient reduction of silver ions to AgNPs. The preparation process was optimized by varying the pH (6 and 8), impacting nanoparticle size and morphology. Characterizations using UV-Vis spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy confirmed the formation of crystalline AgNPs with a face-centered cubic structure. The results demonstrate that alkaline conditions (pH 8) yielded smaller, more uniformly distributed AgNPs with superior stability than those prepared at pH 6. This green synthesis method offers a promising approach to producing AgNPs while promoting sustainability and resource efficiency. The study highlights the potential for waste valorization and the development of eco-friendly nanomaterials for various applications.

The interactions of a novel quinoline-based N₃O₆ polydentate chelator, CYTOM5OX, towards La³⁺ and Er³⁺ have been examined by solution thermodynamics, coordination behavior, photophysical, and DFT studies. The influence of pH on the complexation behavior has been explored by adopting pH-metry, electronic absorption, and emission spectroscopic techniques. The potentiometric and spectrophotometric studies established six pKa values for CYTOM5OX between 2.8–10. Lanthanide ions form thermodynamically stable complexes with the ligand, giving high formation constants log β₁₁₀ = 30–35 and pLn = 20 − 24. Irrespective of the lanthanides used, the monometallic Ln(LH) is the main species formed at neutral pH. The principal coordination sphere contains two and three aqua molecules for La(CYTOM5OX) and Er(CYTOM5OX), respectively, according to time-resolved photoluminescence experiments in an H₂O and D₂O solvent at a pH of 7.0. Both absorption and emission studies of these compounds show significant spectral changes. The probe showed simultaneous sensing of La³⁺ and Er³⁺ ions in the visible range under neutral pH, exhibiting a green fluorescence. To validate the experimental findings, the ground state and excited state theoretical spectra of the species have been computed from DFT-optimized structures using the GGA (BLYP-D3) functional and the PM7-Sparkle energy-minimized geometries at CIS excitation levels using the ZINDO/s approach.

The fabrication and chelation of Ln(III) metal ions (Ln = Eu and Tb) with ligands i.e.; N-[3,5-bis[(1-hydroxy-6-oxo-pyridine-2-carbonyl)amino]cyclohexyl]-1-hydroxy-6-oxo-pyridine-2-carboxamide, (TACH-1,2-HOPO) (L₁) and N,N',N''-(((1R,3R)-cyclohexane-1,3,5-triyl)tris(methylene))tris(1-hydroxy-6-oxo-1,6-dihydropyridine-2 carboxamide), (TMACH-1,2-HOPO) (L₂) made up of three 1,2-HOPO units attached with tris-aminocyclohexane and tris-aminomethylcyclohexane framework are reported. The Eu(III) and Tb(III) complexes with hexadentate L₁ and L₂ are evaluated in terms of their thermodynamic stability in aqueous solution by potentiometric and spectrophotometric methods. The UV–visible absorption and luminescence properties are also studied. The overall stability constants, logβ₁₁₀ were found to be 13.98 and 10.75 for Eu(III) and Tb(III) complexes respectively with L₁, whereas for L₂ they were found to be 11.29 and 10.24 for Eu(III) and Tb(III) respectively. Complexes of both the ligands exhibit significantly similar characteristics in terms of stability and photophysical aspects and are found to be nine-coordinated in which the ligand is coordinated to three pairs of O–O donor atoms of three 1,2-HOPO moieties along with three coordinated water molecules forming a distorted tricapped trigonal prismatic geometry. From the computational studies, it was observed that the metal ions are wrapped in the ligand's cavity without affecting their fundamental geometry. The density functional theory (DFT) method has been used to elucidate the coordination behavior and experimental absorption properties of lanthanide complexes. Furthermore, NBO and ETS-NOCV studies were also carried out to investigate the nature of bonding.

Curcumin (CUR) is a polyphenol known for its therapeutic potential, but faces limitations in clinical application due to its poor aqueous solubility and low bioavailability. This study envisaged developing stable ternary inclusion complexes of CUR with β-cyclodextrin (βCD) and ascorbic acid (AA) as the ternary substance. Inclusion complexes were prepared by kneading and autoclaving method. Phase solubility studies revealed that the A_L type relation between CUR and βCD. We observed The AA improved the stability of the ternary complexes with its stability constant as 138.8M^− 1, complexation efficiency as 0.198, utility number as 3.96 and the bulk as 4.80. The solubilization power improved from − 17.42 to 1.33. Cytotoxicity assays using the A549 lung cancer cell line demonstrated that the ternary complex exhibits potent anticancer activity, comparable to pure CUR. In vitro dissolution tests showed a marked increase in the release rate of CUR from the ternary complex. Our study demonstrates that the inclusion of AA significantly enhances the solubility, stability, and biological efficacy of CUR. The higher stability constant and complexation efficiency of CUR-βCD-AA was due to improved interaction facilitated by AA. The inclusion complexes showed improved antibacterial activity against Staphylococcus aureas and Staphylococcus epidermis Enhanced dissolution rates and strong cytotoxic effects against A549 lung cancer cells further support the potential of this ternary complex in overcoming CUR’s bioavailability limitations. These results suggest that the CUR-βCD-AA ternary complex effectively enhances curcumin’s solubility, stability, and anticancer activity, offering a promising formulation strategy to overcome curcumin’s bioavailability challenges and improve its therapeutic potential.

Here, a new ‘hybrid’ β-diketonato ligand derived from the structure of coumarin and chalcone precursors, namely L, has been designed and synthesised, and the complete structural characterisation was achieved using NMR spectroscopy and X-ray diffraction studies. Potential applications of this compound include metal detection and/or sensing, as well as potential bioactive functions.

Novel monoaza-15-crown-5 ethers have been synthesized with an α-d-mannopyranoside backbone. These chiral catalysts contain different heteroaromatic side chains, which have never been incorporated in sugar-based crown ethers before. The novel macrocycles together with a few previously synthesized mannose-based crown ethers were examined in four asymmetric phase-transfer cyclopropanations. The reactions proceeded mainly with excellent yields (up to 99%), while enantiomeric excesses ranged from 1 to 44%, proving the mannose-based lariat ethers to be moderate enantioselective catalysts in these reactions. The distance between the crown ring and the functional group of the side chain proved to be important in terms of enantioselectivity, the propylene moiety was more favorable than the ethylene bridge. The type of heteroaromatic ring also affected the catalytic activity of the mannose-based macrocycles, using lariat ethers containing a pyrrole unit, higher enantiomeric excess was measured.