Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Cyclosporine A (CP) inclusion complex using cyclodextrin (binary) and cyclodextrin with TPGS (ternary) was prepared by the freeze-drying method. The phase solubility study was performed to calculate the solubility parameters. The prepared formulations were evaluated for saturation solubility and drug release studies. The spectroscopy and molecular docking studies were performed to confirm the formation of inclusion complex. The phase solubility results revealed a high stability constant for both binary and ternary samples. A significant enhancement in saturation solubility and dissolution was found in the prepared inclusion complexes. The spectroscopy studies revealed no interaction between the drug and carrier. The molecular docking study displayed the formation of a stable complex with a good docking score. The diffraction pattern showed the conversion of crystalline CP into an amorphous form after the formation of the inclusion complex. The findings were also supported by the saturation solubility study, which showed a significant enhancement in solubility. From the results, it can be concluded that Cyclosporine A inclusion complex using HP βCD with TPGS is an excellent delivery system. Therefore, the prepared delivery systems may be an alternative to the conventional delivery system for enhanced solubility of highly lipophilic drugs.

Three new dinuclear triple helicates were synthesised using a ditopic semi-rigid pyridylylimine ligand L, separated by a diphenoxy-biphenol spacer providing considerable length to the backbone. L and the new large dinuclear triple helicate complexes [Fe₂L₃](BF₄)₄ (1), [Ni₂L₃](BF₄)₄ (2) and [Zn₂L₃](BF₄)₄ (3) have been characterised in solution and solid state. Single crystal X-ray diffraction was used to investigate overall complex ion shape as the coordination sphere was modulated by metal ion selection. Small differences in complex shape were seen to arise due to subtle distortions in coordination sphere environments. This study sheds light on how the length and twist of dinuclear triple helicates can be tuned by selection of coordinating metal ion.

We have developed a chemosensor using calix[4]arene, which features a thiosemicarbazone binding/sensing unit and a naphthalene chromogenic group. Our objective was to understand the intricate binding affinity of these chemosensors towards a diverse range of anions and cations using UV–Visible, HNMR and IR spectroscopic techniques. We showed that this chemosensor can form complexes with Ag(I) or Cu (II) and to detect CN⁻ or F⁻ ions by deprotonation of thiosemicarbazone. To understand the behavior of these interactions, our analysis provides information on the interaction patterns between the receptors and the ions. The sulfur and imine nitrogen on the thiosemicarbazone substituent are vital sites of engagement for cation ions, as evidenced by the observed changes in IR. HNMR studies for interaction with anions indicate the involvement of the thiosemicarbazone hydrogens. Interactions taking place during complex formation with cations lead to changes in the color of the solution or solid complex, easy to follow by UV–Vis spectrocopy. Our study improves the understanding of molecular recognition of this chemosensor, highlighting its potential for ion- selective detection.

The inclusion of 1,8-octanediphosphonic acid (OA) in cucurbit[7]uril (Q[7]) has been investigated via a combined solid state and solution study. The reaction of OA and Q[7] in water led to the formation of a 1:1 inclusion compound 1 as a white crystalline material. Synchrotron single crystal X-ray diffraction revealed its detailed structure validated by Raman spectroscopy with featured vibrational modes from both organic molecules. Subsequent ¹H solution NMR data supported the formation of a 1:1 inclusion complex in aqueous solution. The changes in NMR chemical shifts are consistent with the solid-state orientation in which the phosphonic acid groups of OA are oriented externally to the carbonyl portals and the intervening alkyl chain lies within the cavity of Q[7]. However, the solution study also inferred possible formations of other complexes in solution. This work highlighted the advantage of combining solid state and solution studies to reveal the detailed molecular interactions involving complex inclusion phenomena.

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Self-assembly of C-iso-butyl-resorcinolcalix[4]arene (CBCR) with 4-aminopyridine (4-AP) or 3-dimethylaminopyridine (3-DMAP) in ethanol afforded two host-guest complexes CBCR⋅4-AP (1) and CBCR⋅2(3-DMAP) (2), respectively. Supramolecules 1 and 2 were characterized by FT-IR, ¹H NMR, ¹³C NMR spectroscopies and single crystal X-ray diffraction analysis. The antioxidant and antibacterial experiments were conducted on complexes 1, 2 and the starting materials. The 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical scavenging rate could reach 91.73% and 98.55% when the concentration of complex 2 was 500 and 31.25 mg/mL, respectively. The antibacterial test of complex 1 showed that the antibacterial circle diameter against Escherichia coli was 10.25 mm, with a MIC value of 12.5 mg/mL, and the antibacterial circle diameter against Staphylococcus aureus was 14.33 mm with a MIC value of 3.12 mg/mL.

Bis-benzyl 2-(oxy) benzoate substituted axially silicon phthalocyanine was synthesized by the reaction of silicon phthalocyanine dichloride and benzyl salicylate compounds. Characterization of the compound was done by FT-IR, ¹H NMR, ¹³C NMR, UV-visible and Mass spectrum. Photochemical and photophysical properties of new silicon phthalocyanine (SiPc) was investigated. Biological properties of SiPc was carried out by several different parameters. The highest antioxidant ability of 73.18% was obtained at 100 mg/L concentration while the lowest antioxidant activity of 38.46% was obtained at 6.25 mg/L concentration. The antimicrobial effects of SiPc were investigated against different bacteria and microfungi. The results regarding the antimicrobial activity of this compound 3 showed that E. faecalis (ATCC 29,212) was the most sensitive microorganism to the tested compounds, while C. tropicalis was the most resistant microorganism. In addition, when the antimicrobial photodynamic treatment of SiPc was examined, a better activity was observed against all microorganisms. DNA fragmentation activity and microbial cell viability of compound 3 was investigated. SiPc showed excellent DNA nuclease activity and 99.96% inhibition of cell viability at 100 mg/L. The effect of compound 3 on antibiofilm activity fabricated by S. aureus and P. aureginosa was also measured and a good biofilm inhibition values of 86.51% and 75.24% was achieved at 50 mg/, respectively. In addition, when the antidiabetic effects of the compounds were examined, it showed an antidiabetic effect of 20.14% at 400 mg/L.

DNA molecules have excellent molecular recognition abilities through the complementary hydrogen-bonded base pairing. Since the hybridization of oligonucleotides can be programmed based on the sequences of the nucleobases, a great number of DNA supramolecular architectures have been constructed via self-assembly processes. The development of stimuli-responsive DNA supramolecules has attracted increasing interests because it will contribute to the construction of dynamic molecular systems such as molecular machines. Metal ions are considered as useful chemical stimuli, but the construction of metal-responsive DNA systems is still in the early stage. This review article describes current progress on the development of DNA supramolecules whose structure and function can be regulated in response to metal ions, with mainly focusing on our recent studies. The basic strategy is the introduction of unnatural metal ligands that form interstrand metal complexes in DNA structures. For example, artificial metal-mediated base pairs, formed through complexation between ligand-type nucleobase analogs and a bridging metal ion, were incorporated into known DNAzymes (catalytic DNA) to allosterically regulate their activity in a metal-responsive manner. Novel ligand-type nucleobases that form both metal-mediated and hydrogen-bonded base pairs have been recently devised as metal-responsive building blocks, and were used to construct a simple prototype of DNA molecular machines. Branched DNA structures bearing metal ligands at the junction core were also synthesized as novel structural motifs, with which metal-mediated structure transformation was demonstrated. These metal-responsive DNA supramolecules are expected to expand the toolbox of DNA-based supramolecular chemistry and nanotechnology.

Binding constants for host-guest cyclodextrin systems have been estimated recently through the small-cost GFN2-xTB semiempirical quantum method in a multi-equilibrium scope. This work applied such an approach to investigate the inclusion of fenchone and camphor into α-cyclodextrin. The computational cost associated with GFN2-xTB and the supramolecular arrangements automated obtained by UD-APARM allowed the investigation of an unprecedented 18,615 starting systems (8640 for 1:1 guest/CD and 5184 + 2232 + 2559 for 1:2 guest/CD stoichiometry). According to the present study, only 18 (0.21%) for 1:1 associations and 45 (0.45%) for 1:2 associations contribute to the binding constants. The chiral recognition was achieved for the four inclusion compounds investigated: (−)-fenchone@(α-CD)₂, (+)-fenchone@(α-CD)₂, and (−)-camphor@(α-CD)₂ and (+)-camphor@(α-CD)₂. When experimental and theoretical GFN2-xTB (ALPB) binding constants were compared, a linear correlation with an R² equal to 0.9933 was obtained. Estimated error varied from 1 to 3% to adjusted GFN2-xTB values. Furthermore, the theoretical data supported the experimental information that two CD units encapsulate camphor guests, increasing their stabilities. The procedure adopted can be expanded to investigate other 1:1 and 1:2 chiral host-guest systems for which it was addressed that finding out representative host-guest systems correspond to the bottleneck in the use of the discussed GFN2-xTB/UD-APARM multi-equilibrium approach.

Graphical abstract

A new tripodal siderophore-mimic hexadentate chelator, 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) containing three 1,2-hydroxypyridinone units attached to a cyclohexane ring through amide linkage at 1,3 and 5 positions have been designed, synthesized, and characterized by FT-IR, ¹H NMR, ¹³C NMR, ESI-MS, and electronic spectroscopy. The solution thermodynamics and photophysical properties of the ligand and its metal complexes (M = La³⁺, Gd³⁺, and Lu³⁺) were investigated experimentally and theoretically in an aqueous medium. The pK_a values for the ligand were found to be 8.32, 6.86, and 5.45. In an aqueous solution, the ligand formed complexes of the type MLH3, MLH2, MLH, and Mion. Additionally, it formed three hydrolyzed species, MLH_− 1, MLH_− 2, and MLH_− 3 at a higher pH. DFT studies were performed, which support the experimental results. The nature of bonding between the lanthanide ions and the ligand was explained by NBO, Morokuma Ziegler energy decomposition analysis (ETS-NOCV).