Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

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.

While the world is in search of a vaccine that can cure COVID-19 disease, favipiravir is the most commonly used antiviral drug in the treatment of patients during the pandemic process. In this study, we investigated the host–guest interaction between the popular supramolecule calix[4]arene derivatives and the favipiravir drug by using the DFT (Density Functional Theory) method. The B3LYP hybrid method and 6-31G (d,p) basis set were utilized to determine the optimized structures of the host and guest molecules and their complexes. The negative adsorption energy (∆E) and adsorption enthalpy (∆H) calculated for the complexes formed between calix[4]arene compounds and favipiravir drug molecule mentioned that adsorption of favipiravir molecule was an exothermic process on calix[4]arene structures. On the other hand, among the calixarene derivatives in the study, Gibbs free energy change (∆G) value for the adsorption was only negative on calix[4]arene4 molecule. The infrared spectroscopy (IR) calculations were performed by examining the C=O, O–H and NH₂ vibrational frequencies to see the adsorption behavior in the favipiravir-calix[4]arene complex. After adsorption of the favipiravir molecule, HOMO–LUMO gap values decreased significantly for the structures and therefore electrical conductivity increased proportionally. In addition, sensor response factors, Fermi energy levels and workfunction changes of calix[4]arene derivatives were calculated and examined. Charge transfer between the four calix[4]arene compounds and the favipiravir molecule has occurred after adsorption. This attributes that calix[4]arene derivatives can be used as a well-suited favipiravir sensor (electronic and workfunction) and adsorbent at room temperature. Based on the calculations made to see the solvent effect on the adsorption of favipiravir it was determined that it did not affect the interaction between the drug molecule and the calix[4]arene compound too much and the adsorption energy turned into a slightly less negative value.

The pathological origin of Alzheimer’s disease (AD) remains uncharted terrain, despite intensive investigation. Discriminating aberrant proteinaceous deposits, such as β-amyloid (Aβ) and (hyperphosphorylated) tau protein by imaging methods, is a vital tool to support investigations towards the network of interacting features that results in AD pathology. In this context, multispectral fluorescence imaging (MSFI) has drawn much attention enabling the distinction of several analytes with merely a single fluorophore emitting a multichromatic fluorescent signal. Herein, we developed three kinds of benzimidazole-derived fluorescent dyes, BZ1–BZ3. The photophysical properties and intramolecular charge transfer (ICT) characteristics of the probes were evaluated in various solvents. Furthermore, a benzimidazole-associated polar-sensitivity displayed multichromatic behavior and enabled the visualization of minute differences in microenvironmental polarity between Aβ and tau aggregates, resulting in different maximal fluorescent emission wavelengths. Indeed, BZ2 demonstrated an approximately 30 nm bathochromic shift in maximal fluorescent emission. All these observations offer a potential for the development of a future generation of benzimidazole-derived ICT-based fluorescent probes.

A methylene crosslinked calix[4]arene tetracarboxylic acid resin that exhibits high precious metal adsorption properties was prepared. The maximum loading capacity of this resin was compared with that of an unmodified methylene crosslinked calix[4]arene resin to verify its applicability for platinum and palladium adsorption. The introduction of multiple acetic acid groups improved the adsorption capacity for divalent palladium, while that for tetravalent platinum was slightly suppressed. The newly obtained capacity of palladium was 1.17 mmol/g, while that of platinum was 0.23 mmol/g. The stoichiometry of Pd(II) to the calix[4]arene tetracarboxylic acid monomer in the methylene crosslinked tetracarboxylic acid calix[4]arene resin was found to be 1:2, while that of Pt(IV) to the same monomer was 9:1. Linear and non-linear methods were applied to evaluate the fitting of the Langmuir and Freundlich models for the studied adsorption isotherm. The results showed that the adsorption isotherm was consistently fitted by the Langmuir model. Further, the non-linear method was found to be more suitable for obtaining the isotherm parameters.

The host and guest supramolecular interactions between symmetric dicyclohexanocucurbit[6]uril (CyH₂Q[6]) and 1H-benzotriazole (BTA) were investigated using nuclear magnetic resonance spectroscopy, isothermal titration calorimetry (ITC), MALDI-TOF mass spectrometry and single-crystal X-ray diffraction analysis. From the experimental results, it was concluded that there was a 1:1 mode of inclusion in BTA@CyH₂Q[6]. In addition, the benzene ring of the BTA molecule entered the cavity of CyH₂Q[6], while the triazole part was at the port of the CyH₂Q[6], forming a supramolecular framework. According to ITC, the complexation process for BTA with CyH₂Q[6] is exothermic and mainly driven by enthalpy.

The binding properties of 1,ω-bisbenzimidazolyl derivatives with cucurbit[6]uril (Q[6]) and cyclohexanocucurbit[6]uril (Cy6Q[6]) host, for 1:1 stoichiometry, have been studied using density functional theory. The distance between the two benimidazole acidic hydrogen’s along with the flexible butyl spacer group play a vital role in the complexation with host. The energetic analysis exhibits strong complexation ability of guests with Q[6] than Cy6Q[6] host. The computed enthalpy and free energy change were negative indicating the encapsulation process to be spontaneous and thermodynamically favorable and enthalpy driven. The global reactivity descriptors based charge transfer calculations show that charge transfer occurs from the guest to host molecule which was supported by the electron density difference map. The main factors for the higher stability of stable complex was the presence of C–H····O=C hydrogen bonding interactions in addition to the weak C···O, C···N, N···O, C···H, H···N type of interactions. AIM topological parameters and NCI analysis reveals the existence of weak interaction, mainly of electrostatic in nature and more number of hydrogen bonds are present in stable complexes. EDA analysis demonstrates the presence of noncovalent and electrostatic interaction with partial covalent character in the encapsulated complexes. The lower stability of Cy6Q[6] complexes compare to Q[6] are due to the presence of positive V_s,max values of cyclohexanone methylene hydrogen’s on Cy6Q[6] host.

Graphic abstract

Leaving a mixture of excess N,N,N′,N′-tetramethyl-1,4-butanediamine (Me₄BDA) with p-t-butylcalix[8]arene (L) and [(UO₂)(dmso)₅](ClO₄)₂ in a 1:2 ratio in acetonitrile solution to stand for an extended period resulted in the deposition of a mixture of three different crystalline materials. Single crystal X-ray structural studies were carried out to determine that the three materials were the solvated uncomplexed macrocycle L.1.5MeCN, and two uranyl complexes. These were formulated as (Me₄BDAH₂)²⁺[(HO)(UO₂)₂(L-5H)]^2–·9MeCN·H₂O and (Me₄BDAH₂)²⁺[HO(UO₂)₂{L-5H)]^2–·(Me₃BDAH)⁺[H₂O(UO₂)₂(L-5H)]⁻·Me₄BDA·14MeCN·H₂O·CH₃OH respectively. In contrast to analogous systems based on 1,2-ethanediamine and 1,3-propanediamine derivatives, extension of the chain length separating the N-centres to (CH₂)₄ in the present systems has resulted in the formation of polymeric chains where the calixuranate anions are linked by H-bond acceptance from diammonium units. These links are still not completely direct and pass in part through solvent bridges. Direct double interactions do occur in the inverse situation where the calixarene acts as an H-bond donor to neutral 1,4-butanediamine species but lead only to dimerisation.

The chiral separation of terbutaline (TB) using β-cyclodextrins (β-CD) and its derivatives has aroused intensive interest. Herein, the enantioseparation mechanisms of β-CD and heptakis(2,3-di-O-acetyl)-β-CD (HAD-β-CD) towards TB are investigated by a molecular dynamics/quantum mechanics/continuum solvent model (MD/QM/CSM) approach based on the experimental data. One of the two experimentally predicted binding modes of HAD-β-CD/TB is confirmed by our approach and ascribed to the R-complex. R-TB is compactly included by HAD-β- CD: the aromatic ring is within the CD cavity, while the alkyl moiety is also included and almost parallel to the secondary rim of the CD. As indicated by the computed binding affinity, this tight binding mode of R-complex enhances the host–guest hydrophobic interaction and renders the R-complex significantly more stable than the S-complex. In contrast, the binding modes of R- and S-TB with β-CD are similar due to the poor flexibility of the host, which jeopardizes its ability to differentiate R- and S-TB.