Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Hosts, a key component of inclusion complexes, are cyclic oligomeric compounds containing a cavity in which another component of the complex is bound by non-covalent forces. Chiral hosts are particularly important and interesting because they allow the study of specific intermolecular interactions and molecular recognition. The most important classes of chiral hosts and their physicochemical properties are briefly reviewed. An important part of this Review is the description of selected concepts necessary to understand the properties and behavior of inclusion complexes studied by the most suitable analytical method for studying inclusion complexes—nuclear magnetic resonance.

The geometrical structures of cucurbit[n]uril (CB[n], n = 5–8 and their complexes with molnupiravir (MLP) drug have been investigated using the DFT computations. The complexation energies and electronic properties of CB[n]/MLP complexes were also computed. The host–guest interactions in the complexation are occurred through the of dipole–dipole interactions which are the hydrogen bonds between the O−H or N−H of molnupiravir and oxygen atoms of CB[n]s. The CB[n]/MLP host–guest complexation in both gas and water are found to be an exothermic reaction with negative complexation energy values. By means of the NBO analysis and MEP contours, the partial charge transfers from CB[n]s to molnupiravir are displayed. After drug complexation, the electronics properties of CB[n]s are significantly changed. This means that CB[n]s can act as a host for appropriately molnupiravir guest, even in aqueous solution.

Thymol and carvacrol belong to the class of terpenoids that usually contribute to the flavor, color, and development of plants, and their complexation with CD has been recently reported. Due to their structural similarities, including such guests in CD poses a challenging task to theoretical methodologies. With the present contribution, we applied the recently developed GFN2-xTB multi-equilibrium approach to study the inclusion of those guests into β-CD. The inclusion of 1-adamantane carboxylic acid in β-CD was also investigated for comparison. The study was conducted with a progressive increase in the number of systems in steps, comprising 792, 1,188, and 1,584 systems. Therefore, for the three guest/host pairs studied, complete optimization in vacuum and water with the ALPB continuum method was applied to 10,692 systems at the GFN2-xTB level of theory. Furthermore, single-point calculations at the B97-3c/def2-TZVPP level of theory were carried out using the SMD solvation model. As a result, beyond determining the experimental trend, we addressed that the additional degree of freedom represented by the gamma Euler parameter decreased the errors related to the estimated adjusted binding constants. On the other hand, the use of the B97-3c/def2-TZVPP in conjunction with the set of systems selected by GFN2-xTB (ALPB) must be further investigated since the experimental trend was obtained only with a basis in the difference in electronic energies.

Graphical Abstract

1,4-Phenylene-bis(di-p-tolylmethanol) (H), a host compound with the wheel-and-axle design, formed complexes with organic guest solvents pyridine (PYR) and 2-, 3- and 4-methylpyridine (2MP, 3MP and 4MP). The host: guest (H: G) ratios were 1:3, 1:2, 1:2 and 1:1, respectively. Host crystallization experiments from mixed guests demonstrated H to prefer both PYR and 4MP; however, it was established that these difficult-to-separate (by fractional distillations) guest mixtures cannot be purified/separated by means of H through supramolecular chemistry strategies owing to these selectivities for PYR and 4MP being less than optimal. Single crystal X-ray diffraction experiments showed that each guest compound was held in its complex by means of a classical hydrogen bond with H, and that one of the preferred guests, PYR, experienced a significantly shorter contact of this type than the other guests. Hirshfeld surface analyses demonstrated that PYR was also involved in a greater percentage of (guest)N···H(host) interactions compared with the other guest molecules. Thermal analyses, on the other hand, revealed that 4MP (also a favoured guest species) formed the most stable complex of the four in this investigation. These results with H were compared to those obtained when employing a closely related host compound from a previous report, 1,4-bis(diphenylhydroxymethyl)benzene: while both host species preferred the same guests (PYR and 4MP), the extent of the selectivity of that host compound compared with H in the present work was significantly more enhanced. Thus, minor modifications may deleteriously affect the selectivity behaviour of closely related host compounds.

β-Cyclodextrin plays a crucial role in augmenting the activity of metal complexes by ameliorating their solubility, stability, and reactivity, therefore the thio-functionalized β-cyclodextrin based amino ligand mono-6-deoxy-(o-aminobenzylthio)-β-cyclodextrin (4) was synthesized and analyzed by elemental analyses, AAS, UV–visible, FTIR, and ¹H NMR spectroscopy. The newly synthesized Fe III) complex was soluble in water. The Fe(III) complex's spectral analysis using FTIR confirmed that the ligand aided the metal ion coordinate by way of the sulfur atom of the β-cyclodextrin moiety and the nitrogen atoms of the two ligand molecules, with two H₂O occupying the fifth and sixth coordination sites. Additionally, the mass spectrometry verifies that the intended Fe(III) complex has synthesized. Density functional theory (DFT) was used to calculate different electronic parameters of the optimized structure of Fe(III) complex to reveal its stability. Antimicrobial metal complexes that are suitable for therapeutic application are known to be more stable and bioavailable when β-cyclodextrin is introduced, therefore studies have been done to inquire into the possible comparative in vitro antibacterial activity of the Fe(III) complex and free ligand against two gram positive (Bacillus subtilis, and Staphylococcus aureus) and two gram negative bacteria (Escherichia coli, Klebsiella pneumoniae) strains. Molecular docking was used to further corroborate these capabilities.

The effective binding of Rhodamine B (RhB), a xanthene dye, in solutions of amphiphilic sulfobetaine tetrapentylcalix[4]resorcinarene (C₅-SB) at millimolar concentrations has been found. Using the FT-PGSE NMR technique, it was determined that the binding fraction (P_b) of RhB in the solution with a С(RhB)/С(С₅-SB) ratio of 3.75 mM/5 mM was 0.57, whereas in a solution with an order of magnitude lower concentration, the P_b was only 0.12. This significant difference in interaction is also supported by 2D NOESY and ¹H NMR spectra. Based on fluorimetry data, it appears that the influence of C₅-SB on the spectral properties of RhB increases as the C₅-SB/RhB molar ratio increases, but decreases as the concentration of C₅-SB and RhB decreases. By comparing the spectral properties of RhB in the presence of C₅-SB and tetrapentylcalix[4]resorcinarene with carboxylic (C₅-COO⁻) and trimethylammonium (C5-N⁺Me₃) peripheral groups, an assumption about the driving forces behind RhB, which led to an enhancement of the emission properties of the dye, was made. The study demonstrates the possibility of controlling the emissive properties of a xanthene dye by binding it to a supramolecular associate with amphiphilic calix [4] resorcinarene.

Physical manipulation can be carried out on molecules and cells through the utilization of nanomachines which are machines with nano dimensions. There are different types of nanomachines. Among them, rotaxanes stand out as the most well-known. The term of rotaxane originates from the combination of the Latin words wheel and axis. The application of nanomachines is identifying and measuring the concentration of toxic substances in the environment, targeted drug delivery and cancer diagnosis. The objective of this study is to synthesize and identify several new nanomachines in the form of rotaxanes (internally locked molecules) with nanopharmaceutical properties from the corresponding crown compounds. In the first step, 2,2-dimethylphenol was converted into bisphenol compound (1) in reaction with thionyl chloride. Bisphenol compound (1) was converted into methyl diester compound (2) in reaction with methyl chloroacetate. The methyl diester compound (2) reacts with the appropriate diamine to form the diamide macrocycle compound (3). Rod (4) is prepared from the reaction of diethylene glycol ditosylate, 4,4-bipyridine and a bulk phenol such as 4-tert-butylphenol in DMF. Each of the rings in the presence of the prepared rod leads to the corresponding rotaxane compound (5). Chemical structure of the obtained compounds were established by ¹HNMR, ¹³CNMR, FT-IR and SEM spectroscopic methods.

The reaction of a square-planar platinum(II) complex containing two bis(2-diphenylphosphinoethyl)phenylphosphine (triphos), [Pt(triphos)₂](NO₃)₂, with [Au(tu)₂]Cl (tu = thiourea) gave a new trinuclear Au^I₂Pt^II complex, [Pt(triphos)₂{Au(tu)}₂]Cl₂(NO₃)₂, through Au-P coordination. While the [Pt(triphos)₂]²⁺ unit in [Pt(triphos)₂](NO₃)₂ adopted the trans-meso configuration, only the cis-racemic isomer was observed for [Pt(triphos)₂{Au(tu)}₂]Cl₂(NO₃)₂. ³¹P NMR spectroscopy indicated rapid equilibrium among the possible isomers of [Pt(triphos)₂]²⁺, which facilitated the trans-to-cis transformation at the Pt^II center in this system. Additionally, we observed that this structural transformation led to an increase in the emission intensity.

To improve the efficiency of cyclodextrins as carotenoid carriers, the kinetics and thermodynamics of the inclusion complex formation between modified β-cyclodextrin (βCD-NH₂) and β-carotene (βCT) were studied using surface plasmon resonance (SPR) at pH 7.4 and theoretical calculations. The observed dissociation rate of the [βCD-NH₂/βCT]° inclusion complex is small ((2.59times 1{0}^{-1} {text{s}}^{-1})), indicating that βCD-NH₂ only interacted with the βCT ionone group to form inclusion complex. The βCD-NH₂/βCT binding constant is (2.80times 1{0}^{4} text{L} {text{m}text{o}text{l}}^{-1}) (at 298.15 K), and its temperature dependence indicates that the [βCD-NH₂/βCT]° formation is driven by hydrophobic interactions (({Delta }H^circ = 28.83 text{k}text{J} text{m}text{o}{text{l}}^{-1}) and (T{Delta }S^circ = 54.21 text{k}text{J} text{m}text{o}{text{l}}^{-1})) caused mainly by the βCT end group desolvation. In contrast, the formation of the [βCD-NH₂/βCT]^‡ activated complex via association between free molecules and dissociation of [βCD-NH₂/βCT]° occurred with the overcoming of an energy barrier ((E_{a}^{ddag } = 40.77~{text{kJ mol}}^{{ - 1}} ~) and ({E}_{d}^{ddag}=11.94 text{k}text{J} text{m}text{o}{text{l}}^{-1})) and decrease in entropy ((T{varDelta S}_{a}^{ddag}=-11.70 text{k}text{J} text{m}text{o}{text{l}}^{-1}) and (T{varDelta S}_{d}^{ddag}=- 65.92 text{k}text{J} text{m}text{o}{text{l}}^{-1})).

Bone adhesives are known as a promising fracture treatment material because they can quickly heal broken bones. However, the existing bone adhesives have the disadvantages of weak binding ability to bone tissue, non-absorption, or difficulty in curing under wet conditions, which limits their wide application in the field of bone tissue engineering. In this study, the raw material of magnesium phosphate bone adhesive was modified, and the composite material of magnesium phosphate bone repair was prepared by the method of solid–liquid blending crosslinking. Mineral-organic composite, a new type of bone adhesive was prepared using calcined dolomite and montmorillonite as mineral components, phytic acid and gelatin as organic components. The compressive strength, porosity and bonding strength of the magnesium phosphate-based bone adhesive were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. When the dosage of dolomite is 8 wt% and the concentration of gelatin is 9 wt%, the adhesion strength of the bone adhesive is 2.04 MPa after 168 h placement. And the compressive strength of the bone adhesive was 6.66 MPa after 168 h placement. After the prepared bone adhesives were immersed in SBF solution for 14 and 21 days, EDS analysis showed that the accumulated material was bone-like hydroxyapatite, indicating that the prepared bone adhesives had good osteogenic activity. In addition, it was also found that the bone adhesive had fluid absorption ability and no cytotoxicity. So, conclusively it can be stated that such newly synthesized bone adhesive has significant medical potential.