Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Porous high surface area supramolecules have been widely researched for controlled delivery and chemical stabilization of active molecular species. Metal–organic frameworks (MOFs), a vast category of high surface area microporous compounds, can be tailored to encapsulate specific active molecules, and control their release kinetics in the headspace of a product-package system for treatment and shelf-life extension of various agricultural produce. Hexanal has been widely reported to reduce post-harvest losses due to its antimicrobial, antifungal, ethylene-modulating, and phospholipase D (PLD) inhibiting characteristics. In this work, we synthesized Calcium-Squarate MOF by a quick simple mechanochemical process using bioderived linkers and non-toxic endogenous cations. We herein report the encapsulation of hexanal in Ca-Squarate MOF, and probe the strength of non-covalent host–guest interactions of hexanal encapsulated in the pores. The synthesized MOF crystals were characterized by thermal analysis, infrared spectroscopy, and diffraction studies. We observed approximately 20% encapsulation of hexanal by weight using thermo-gravimetric analysis. The infrared spectroscopy and simulation study supported the formation of hydrogen bonds between H atoms of hexanal and O atoms of the Ca-Squarate MOF with the strongest binding affinity of  −3.81 kcal mol⁻¹. Crystals maintained their porous structure and microscale morphologies post-encapsulation, as observed using X-ray diffraction and scanning electron microscopy. These results are encouraging for the potential use of hexanal encapsulated MOFs in active packaging applications.

In this investigation, the wheel-and-axle host compound, 1,4-phenylene-bis(di-p-fluorophenylmethanol) (H), was demonstrated to have inclusion ability for each of PYR, 2MP, 3MP and 4MP (1:1, 1:2, 1:2 and 1:2 were the H: G ratios). In the equimolar guest competition experiments, H was observed to have an overwhelming affinity for PYR and 4MP relative to 2MP and 3MP. In fact, selectivity coefficients calculated from the non-equimolar binary guest competition experiments suggested that this host compound would be an efficient candidate for the separation of all PYR/2MP mixtures and a 40:60 4MP/3MP solution through host-guest chemistry strategies. SCXRD analyses established the preferred guests (PYR and 4MP) to be involved in significantly shorter stabilizing classical hydrogen bonding interactions with H, explaining the selectivity behaviour of this host compound in the guest mixtures. Additionally, Hirshfeld surface considerations also explained this behaviour, but only for PYR. Furthermore, thermal analyses were used to ascertain the relative thermal stabilities of the four complexes and, satisfyingly, the PYR- and 4MP-containing complexes possessed the greater thermal stabilities compared with H·2(2MP) and H·2(3MP), as was demonstrated by a comparison of their guest release onset temperatures.

Novel derivatives of diazadioxocalix[2]arene[2]triazine were synthesized and evaluated for their catalytic effects on direct asymmetric Aldol reactions in organic solvents. Chiral groups were attached to the heteroatom-bridged calix[2]triazine scaffold through reactions involving (R)/(S)-1,2,3,4-tetrahydro-1-naphthylamine with diazadioxocalix[2]arene[2]triazine. Diazadioxocalix[2]arene[2]triazine derivatives were found to be effective catalysts for the reaction of acetone with aromatic aldehydes. According to the obtained results, it has been determined that the moiety of the catalyst affects the configuration of the Aldol product. The Aldol adducts were obtained in excellent yields (93%) and enantioselectivities (96%).

Quercetin (QC) has various biological activities such as anti-inflammatory and antibacterial properties. However, due to its poor solubility and stability, the application of QC in clinical practice is limited. Nanosponge (NS), as a new drug carrier, can significantly improve the solubility of low-soluble drug components, and significantly improve the efficacy and bioavailability of drugs. In this paper, cyclodextrin nanosponges (CDNS) were synthesized by cross-linking β-cyclodextrin with diphenyl carbonate (DPC) in a green and safe synthetic pathway. As wall material, CDNS were further used to encapsulate quercetin and quercetin-cyclodextrin nanosponges (QCNS) were formed. The resultant CDNS and QCNS were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The results showed that CDNS and QCNS were successful prepared. The solubilizing impact of CDNS on quercetin was investigated. The results showed that its solubility in water was 176 times higher than that of pure QC. The cumulative release of quercetin and QCNS over 48 h and the cumulative transdermal penetration over 12 h were measured. The antioxidant and antibacterial properties of QCNS were determined. QCNS exhibited superior stability, permeability, and sustained-release properties compared to pure quercetin, and had notable bacteriostatic and antioxidant capabilities.

Two neutral, dizwitterionic dicarboxylates, N,N,Nʹ,Nʹ-tetramethylethane-1,2-diammonioacetate (L1) and biphenyl-4,4ʹ-diyl-bis(4-carboxylatopyridiniomethylene) (L2), have been used as ligands in syntheses of uranyl ion complexes which exemplify the effect of different reaction conditions. [UO₂(L1)Cl₂]·H₂O (1) has been crystallized at room temperature and is a simple monoperiodic coordination polymer. In contrast, [(UO₂)₄(O)₂(OH)₂(C₂O₄)(L1)₂]·4H₂O (2), obtained under solvo-hydrothermal conditions, contains a tetranuclear, bis(µ₃-oxido)-bridged cluster resulting from uranyl hydrolysis, and additional oxalate coligands most likely due to oxidative degradation of L1, and it crystallizes as a diperiodic coordination polymer with tetranuclear nodes and the sql topology. The same arrangement is found in [(UO₂)₄(O)₂(OH)₂(L2)₃](I₃)₂·6H₂O (3), also synthesized under solvo-hydrothermal conditions, but here the more oxidation-resistant ligand does not generate oxalate, and replacement of the latter by neutral L2 bridges makes this complex cationic. The very large cells of the network in 3 (~ 22 Å × 39 Å) accommodate the triiodide anions formed in situ.

The wheel-and-axle host compounds 9,9′-(1,4-phenylene)bis(fluoren-9-ol) (H1), 9,9′-(ethyne-1,2-diyl)bis(fluoren-9-ol) (H2) and 9,9′-(biphenyl-4,4′-diyl)bis(fluoren-9-ol) (H3) each formed complexes with tetramethylurea (TMU), a polar aprotic organic solvent, with host: guest ratios of 1:2. Single crystal X-ray diffraction revealed that these complexes crystallized in the monoclinic space group P2₁/c, their analyses being performed in P2₁/c for H1⋅2(TMU) and in the alternative setting P2₁/n for both H2·2(TMU) and H3·2(TMU). Furthermore, these inclusion compounds are stabilized by both classical and non-classical hydrogen bonds between the host and guest molecules. Hirshfeld surface analyses demonstrated that the percentage of interatomic (host)H···O(guest) interactions ranged between 7.8 and 10.3%, while thermal analyses showed that the relative thermal stabilities of these complexes were high, with the onset temperatures for the guest release event, T_on, being 83.1 (H1·2(TMU)), 81.1 (H2·2(TMU)) and 90.3 °C (H3·2(TMU)). Moreover, the calculated mass loss percentages, after heating each complex in a controlled manner to release the guest species, correlated closely with those expected for these 1:2 host: guest inclusion complexes. Finally, determination of the activation energies for complex desolvation yielded 148.7 ± 5.4, 128.6 ± 10.8 and 149.4 ± 0.8 kJ·mol^‒1 for H1·2(TMU), H2·2(TMU) and H3·2(TMU) respectively. A single guest desolvation mechanism was at work in the first and last of these complexes, while this mechanism in H2·2(TMU) changed during this process. The H1·2(TMU) inclusion complex has been reported previously, and the results obtained in that work are also compared with those from the present investigation.

Oseltamivir (OST) phosphate is a prodrug, metabolized by hepatic carboxylesterase to its active metabolite (oseltamivir carboxylate). OST is efficient in treatment of influenza, in both children and adults. The protein bonding of the prodrug and its active metabolite is low (42% and 3%, respectively). It has a short half-life 1–3 h but its active metabolite has a half-life of 6–10 h, permitting twice daily administration. The most common side effect is gastrointestinal disturbances that are usually nausea and vomiting and can be reduced when taken simultaneously with food. OST phosphate is a white powder with bitter taste and the marketed oral suspension uses sorbitol for masking it. Cross-linked cyclodextrin polymers are known for their ability to increase the dissolution rate, solubility, stability, and permeability of insoluble drugs and provide prolonged release. Therefore, they are promising drug delivery systems that could improve its pharmacokinetic properties and patient adherence. In this study we focused on developing a therapeutic system of OST using cyclodextrin polymer crosslinked with pyromellitic dianhydride (PMDA CD) to enhance its pharmacokinetic properties and to improve its compliance. PMDA CD polymer and PMDA CD polymer complex with OST were prepared. Physicochemical characterization by FTIR spectra, thermal analysis, DLS, SEM and EDX confirmed the existence of interaction between the two components. The prepared complex has a different pharmaceutical profile compared to OST, with higher stability and a controlled dissolution profile. Toxicity studies showed that the polymer complex has lower toxicity than OST, suggesting the protective effect of the polymer.

Here we report on the host behaviour of compounds N, N’-bis(9-phenyl-9-xanthenyl)propane-1,3-diamine (H1) and N, N’-bis(9-phenyl-9-xanthenyl)butane-1,4-diamine (H2) in the presence of potential guest species cyclohexanone (CYC) and 2-, 3- and 4-methylcyclohexanone (2MeCYC, 3MeCYC and 4MeCYC). H1 only formed a complex with CYC, whilst all four guest solvents were enclathrated by H2. Thermal analyses in conjunction with SCXRD experiments revealed that more energy was required to remove guest species from the crystals of their complexes when they were housed in discrete cavities compared with guest molecules retained in channels. Only in H1·CYC was identified an intramolecular (host)N‒H···N(host) hydrogen bond, while complexes H2·2(CYC), H2·2(3MeCYC) and H2·4MeCYC all experienced strong (host)N‒H···O(guest) hydrogen bonds which assisted in retention of the guests in the complexes; this interaction type was absent in both H1·CYC and H2·2(2MeCYC). Hirshfeld surface analyses demonstrated that the amounts of (guest)O···H(host) interatomic interactions were comparable and ranged between 11.1 and 13.9%. Guest competition experiments showed that H2 possessed an affinity for, more usually, 3MeCYC, despite the complex H2·2(3MeCYC) being the least thermally stable one. Finally, it was established that H1 and H2 would not be appropriate host compounds for separations of mixed cyclohexanones through supramolecular chemistry strategies.

As a booming research theme, heterogeneous catalysts have demonstrated significant advantages over homogeneous catalysts in terms of stability, recyclability, and separability from the reactant mixture. In this study, a supramolecular coordinated polymer (P[5]-SCP) was synthesized by complexing thiazole-derived pillar[5]arene (P[5]) with Pd(II), which was obtained by nucleophilic substitution between 1,4-bis(2-Bromoethoxy) pillar[5]arene and 4-methyl-5-(β-hydroxyethyl) thiazole. The chemical component and structure of the P[5]-SCP were confirmed by NMR, EA, FI-IR, XPS, XRD, SEM, TEM, HR MS. In the Suzuki–Miyaura coupling reaction, the catalytic activity, stability, and recyclability were thoroughly evaluated. The P[5]-SCP had excellent catalytic activity in mild reaction conditions (up to 81% yield) and exhibited little loss of activity after at least five recycles. Furthermore, catalyst P[5]-SCP was easily synthesized from simple raw materials and low-cost, thereby a novel pillar[5]arene based-NHC catalyst was developed in green heterogeneous catalysis.

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