Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

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).

Stabilization of reactive organic species by encapsulation in self-assembly supramolecules is a popular technique. Citral, a common antimicrobial and flavor compound, is highly sensitive to oxidation, especially when exposed to elevated temperature and light. In this study we evaluated the encapsulation efficiency of citral in cyclodextrin-metal organic framework (CDMOF) to prevent oxidation, provide chemical stability, and control the release of citral for various industrial applications including packaging. Computational simulations indicated the formation of stable inclusion complex between CDMOF and citral with binding energy of the IC approximately − 3.89 kcal mol⁻¹. We observed around 11.83% w/w inclusion of citral in CDMOF as measured using TGA. Host–guest interactions between CDMOF and citral were further elucidated using FTIR, DSC, and SEM. Encapsulation of CDMOF in citral offers higher temperature stability, and extended-release kinetics.

Inclusion complexes of benzene (Bz) with cyclodextrins (CD) have been investigated so far using non-NMR techniques in various solvents resulting in conflicting data. Here, the first application of NMR spectroscopy in combination with rigorous statistical analysis of the results has allowed us to determine accurately the stoichiometry of complexes and their association constants. Titration measurements have been performed by ¹H NMR spectroscopy in D₂O at a magnetic field B₀ of 14.1 T. αCD and γCD host molecules form weak 1 : 1 complexes with Bz. In contrast, Bz and βCD build 1 : 1 and 2 : 1 complexes coexisting in solution with large binding constants. Binding of second benzene molecule is strongly cooperative.

New coumarin derivatives C1, C2, and C3 with different substituents (methylphenyl, chlorophenyl, and nitrophenyl) were prepared and characterized using various spectroscopic techniques. C1 and C2 display luminescence when excited at 325 nm, while C3 has weak emission at 335 nm. The binding properties of these derivatives toward transition metals and lanthanum cations were studied using UV-visible absorption spectroscopy, and the former cations were found to form ML₂ complexes by titration method. The chelation of each ligand with metal cations induced changes in their luminescence properties.

A hydroxypropyl β-cyclodextrin (HPCD)/5-fluorouracil (5-FU) inclusion complex was loaded into konjac glucomannan hydrogel successfully by co-assembly. The influence of HPCD on the structure and properties of konjac glucomannan (KGM) hydrogel was investigated. The networks of KGM/HPCD hydrogel became flat and firm after HPCD intervened. The KGM/HPCD hydrogel had diversified microstructures including HPCD molecular cavities, porous lamellar structure in fibrous bands. The X-ray diffractometry (XRD) results reflected amorphous characters of the KGM/HPCD xerogel. The analytical data of Fourier transform infrared spectrometry (FT-IR) and differential scanning calorimetry (DSC) confirmed the supramolecular interactions between KGM and HPCD molecules in the gel network were mainly H-bonding interactions. HPCD improved KGM/HPCD hydrogel by crosslinking physically to construct a novel drug delivery system in the presence of sodium carbonate. The KGM/HPCD hydrogel achieved more effective and sustained drug release, in which HPCD cavities shared responsibility for the controlled release of chemotherapeutic 5-FU molecules. Rheological measurements also showed the presence of HPCD increased the elastic modulus (G') of the novel KGM/HPCD hydrogel.

Graphical abstract

Through co-assembly, a green drug delivery system was successfully constructed with hydroxypropyl β-cyclodextrin/5-fluorouracil inclusion complex loaded into konjac glucomannan hydrogel. By dialysis experiments, the drug 5-fluorouracil release rate from the inclusion complex loaded hydrogel was prolongated remarkably compared to that from single 5-fluorouracil loaded hydrogel. For the inclusion complex loaded hydrogel with different 5-fluorouracil concentrations, or under different physiological conditions, the drug cumulative release appeared also evident difference. This green drug delivery system has important potential application in medical engineering material.