Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Circularly polarized luminescence (CPL) organic dyes are currently receiving a great interest, but there are still not many reported observations of CPL spectra of hydrophobic dyes from aqueous solution. We have prepared hydrophobic pyrene derivatives and dissolved them into aqueous solutions with γ-cyclodextrin (γ-CD) by using grinding technique. Among these derivatives, (pyrene-1-carbonyl)serine (PySer) forms a spatially restricted dimer in the hydrophobic chiral cavity of γ-CD and exhibits excimer emission with a high quantum yield of Φ_f = 0.68. In addition, circular dichroism and CPL signals were induced for the complex. The strong g_CPL value of g_CPL = + 2.2 × 10⁻³ was obtained, which may be attributed to the interaction between the hydroxyl groups in the side chain of PySer with those of γ-CD and it strengthens the chiral dimeric structure.

Graphic abstract

Roof-shaped host compounds trans-α,α,α′,α′-tetraphenyl-9,10-dihydro-9,10-ethanoanthracene-11,12-dimethanol H3 and trans-α,α,α′,α′-tetra(p-chlorophenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dimethanol H6 were assessed for their host potential and selectivity behaviour when presented with single or mixed guest solvents comprising o-xylene, m-xylene, p-xylene and ethylbenzene (o-Xy, m-Xy, p-Xy and EB). H3 included each solvent with 3:1 host:guest ratios, while the ratios preferred by H6 were more varied (4:3, 1:1 and 3:2). More importantly, the selectivity behaviour of these two host compounds was observed to be entirely different: H3 possessed only a very modest preference for o-Xy (37.9–68.2%) when recrystallized from various equimolar binary, ternary and quaternary guest mixtures, while H6 was considerably more selective, preferring m-Xy (the least favoured guest of H3) with selectivities ranging from 57.7 to 91.4% in analogous conditions. The latter result was obtained in o-Xy/m-Xy mixtures and demonstrates that H6 may be employed as a purification tool for mixtures of these two xylenes via host–guest chemistry protocols. A single crystal diffraction experiment on 3(H3)·o-Xy (containing the preferred guest of H3) revealed that the guest was retained in the host crystal by means of a singular (host)m-Ar–H···π(guest) interaction that measured 2.73 Å (148°) as well as numerous other host···guest interactions involving only the aromatic protons of the free host phenyl groups and the guest methyl protons or aromatic carbons and protons (2.20–2.54 Å, 121–125°). Thermal analyses explained the preference of H3 for o-Xy, while these were less informative for the complexes of H6.

Nowadays, biomedical films containing drug carriers are preferred over conventional ones, since the protection of the injury and the therapy is joined within a single device. In the current work, we prepared polycaprolactone (PCL) composite films with β-cyclodextrin (βCD) or its epichlorohydrin crosslinked polymer (βCDP) as ibuprofen (Ibu) drug carrier. The composite films were prepared at different PCL/additive ratios (2, 5, 10 and 20 wt%). ATR-FTIR spectroscopy and water contact angle (WCA) measurements indicated a scarce presence of the additives on the surface. Cross-section scanning electron micrographs showed the presence of aggregates corresponding to βCD and βCDP in the inner regions of the films. The incorporation of βCD and βCDP into the PCL films did not affect their thermal properties as was determined from differential scanning calorimetry (DSC). PCL-films with 10 wt% of the inclusion complexes Ibu@βCD and Ibu@βCDP were prepared and the release studies were performed. At pH = 7.2, PCL-Ibu@βCDP composite film released 55% of Ibu within the first six hours; eight times the amount released by PCL-Ibu@βCD within the same time interval. A plausible mechanism for ibuprofen release is discussed based on the cross-section SEM micrographs of composite films.

The condensation reaction of mono-amido-functionalized pillar[5]arenes with tere- and iso-phthaloyl diisothiocyanates in acetone under ultrasonic irradiation afforded tere- and iso-phthaloylthiourea-bridged dipillar[5]arenes. The similar reaction of mono-amido-functionalized pillar[5]arenes with 1,ω-bis(4-isothiocyanatophenoxy)alkanes also afforded diphenoxyalkylene thiourea-bridged dipillar[5]arenes. ¹H NMR and NOESY spectra clearly indicated that bis-[1]rotaxanes were formed by insertion of longer alkylene chains into the cavities of two pillar[5]arenes. On the other hand, the free-forms of dipillar[5]arenes were obtained with the shorter ethylene chains existing on the outside of the cavities of two pillar[5]arenes.

Graphic abstract

Some novel benzimidazole-bridged aren ruthenium rectangle compounds of the general structure [{Ru₂(p-cymene)₂(µ₄-OO∩OO)}₂(µ₄-bbim)]⁴⁺ (bbim = 1,1′-butyl-2-ene-di(benzimidazole) were obtained from the corresponding double-nuclear arene ruthenium compounds [Ru₂(p-cymene)₂(µ₄-OO∩OO)Cl₂] (OO∩OO = 2,5-dioxido-1,4-benzoquinonato (dobq), 2,5-dichloro-1,4-benzoquinonato (dClbq), 2,5-dibromo-1,4-benzoquinonato (dBrbq), oxalato (oxa), and 5,8-dioxido-1,4-naphtoquinonato (donq) via reaction with the bbim molecule and AgCF₃SO₃. The antiproliferative activity and anti-cancer properties of the tetranuclear arene ruthenium compounds were evaluated against the human breast cancer cell line (MDA-231-MB). Compound 2 showed the highest antiproliferative effect among the compounds during 24- and 48-h administration. In addition, all other compounds exhibited very good cancer cell selectivity and very low micromolar cytotoxicity. The antimicrobial activities of the synthesized compounds were also determined against various test microorganisms. Evaluations were carried out using the disk diffusion method and the dilution method. In particular, the compounds exhibited more potential antibacterial effects against Gram negative bacteria than against Gram positive bacteria and showed a superior antifungal effect against Candida species. The results revealed the benzimidazole-bridged aren ruthenium rectangle compounds to be very strong and potent inhibitors.

Newly phthalocyanine derivative which carries 2,6-dimethoxyphenoxy bioactive groups as tetrakis from non-peripheral positions of the phthalocyanine ring and contains strontium (II) as an alkaline earth metal ion in its cavity was synthesized. Its structure was characterized by elemental analysis, fourier transform infrared, ultraviolet–visible, proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance and matrix assisted laser desorption/ionization time-of-flight mass spectroscopic techniques. Its thermal properties were determined using thermogravimetric analysis and differential scanning calorimetry. The solubility and aggregation behavior in polar protic, polar aprotic and non-polar solvents were determined. Also, its aggregation behavior was studied at a range of different concentrations in dimethyl sulfoxide. The photophysical properties (fluorescence quantum yield, fluorescence lifetime, natural radiation lifetime, non-radiative lifetime, rate constant for fluorescence, non-radiative rate constant and observed fluorescence decay rate constant values) of newly strontium(II) phthalocyanine were determined in dimethyl sulfoxide. In addition, the spectroscopic, thermal and photophysical properties of newly strontium(II) phthalocyanine were also compared with its counterparts reported in the literature. The findings of this work can be useful to those systems involving changes in the forms analogous to the compound studied. In addition, newly strontium(II) phthalocyanine with particularly sufficient and enhanced photophysical properties, could be a photosensitizer candidate for photocatalytic applications.

Porous materials have been widely studied for encapsulation and controlled release of active species for packaging applications. This study examines the encapsulation efficiency of hexanal in γ-cyclodextrin metal organic frameworks (γ-CDMOF) for potential active packaging applications. γ-CDMOF was synthesized and hexanal was encapsulated in the MOF using a vapor diffusion process. The synthesized MOF was characterized both before and after the encapsulation of hexanal using x-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The diffraction peaks of various planes obtained from XRD characterization matched the theoretically calculated values. We identified the most stable docking sites using energy minimization calculations. FTIR and computational studied indicated hydrogen bonding interactions play a significant role in the stabilization of hexanal and γ-CDMOF inclusion complex. TGA characterization results revealed an encapsulation efficiency of about 15%. DSC and SEM study also supported encapsulation of hexanal in γ-CDMOF.

In this work, calix[4]arene was used as a building block for the preparation of 1,3-alternate calix[4]arene tetrabenzoic acids. Two structural isomers, 3A and 3B were obtained which have the carboxylate groups on the para and meta positions, respectively. The reaction conditions were optimized to obtain, four coordination polymers with linkers of 3A and 3B with Zn²⁺ and Cd²⁺ in different forms. Structural analysis of the product (CU-SCRU1) from 3A with Zn²⁺ showed that it was a 1D polymeric chain. In the case of 3B with Zn²⁺ it was a 1D polymeric chain in a zig-zag shape (CU-SCRU2). The free rotation of the methylene bridge allowed the carboxylate group at the meta position of 3B to coordinate with the Zn²⁺ ion. In both cases, the carboxylate groups at each side of the organic linkers, 3A and 3B, chelated to the same metal center (Zn²⁺) which resulted in the formation of 1D coordination polymers. However, each polymeric chain extended to a 3D framework by nonclassical hydrogen bonding and intermolecular interactions for CU-SCRU1 and CU-SCRU2, respectively. The reaction of 3B and Cd²⁺ provided coordination polymers that were suitable for structural characterization. Interestingly, two products were formed in the same reaction, CU-SCRU3 and CU-SCRU4, that had different coordination structures. The structural features of these two products suggested that they exist as a 3D framework, however, the nitrogen adsorption–desorption analysis revealed that they were nonporous materials.

Graphic abstract

The synthesis and spectroscopic and structural characterisation of new 3,5-dibromophenyl-functionalised imidazolium salts and their corresponding [Au(NHC)₂]⁺ complexes is reported. X-ray diffraction studies revealed intra- and intermolecular interactions involving the 3,5-dibromophenyl group, including Br…π interactions with imidazolyl and C₆ arene rings. Au-NHC complexes functionalised with 3,5-dibromophenyl substituents showed potent activity against OVCAR-8 (ovarian cancer) cells at low micromolar concentrations.

The interaction of the newly approved pharmacon esketamine with HSA (human serum albumin) has been investigated by various spectrographic methods. The fluorescence quenching results of HSA by esketamine revealed that the 1:1 ground state complex has formed. The results of binding parameters lead to the conclusion that the reaction was exothermic. In the presence of esketamine, HSA was found to undergo partial unfolding, and thermodynamic parameters (ΔG° = − 2.08 × 10⁴ J·mol⁻¹, ΔS° = 35.7 J·mol⁻¹·K⁻¹, and ΔH° = − 1.20 × 10⁴ J·mol⁻¹ at 298 K) revealed that electrostatic forces dominated the stabilization of the complex. The qualitative and quantitative analyses of conformational changes of HSA were conducted using circular dichroism, three-dimensional, and synchronous fluorescence spectroscopy, revealing the loosening of skeleton structure and adaptive modifications of secondary structures. Fe³⁺ and Mg²⁺ may help prolong the storage time and improve the drug efficacy.