Journal of Inclusion Phenomena and Macrocyclic Chemistry最新文献

Today, the modification of the organic molecules using the copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) is of great interest, as evidenced by the Nobel Prize in Chemistry awarded in 2022 to the founder of “click” chemistry. Supramolecular chemistry, in turn, is one of the actively developing branches of modern science. Using the CuAAC approach is a very convenient method to obtain new macrocyclic structures of interest. This review focuses on the use of the modular “click”-chemistry approach for the synthesis of various triazole derivatives of thiacalix[4]arenes and calix[4]arenes as well as general routes for the synthesis of their precursors (azides and alkynes). Examples of some functional systems based on triazole-containing macrocycles, such as chemosensors, multicalixarenes, amphiphilic calixarenes as well as examples of the use of triazole calixarenes for bioapplications are described.

Modification of the upper rim of the lipophilic cone-shaped tetrapropoxycalix [4]arene with hydrophilic phosphine oxide groups or phosphinic acid groups yielded nano-sized water-soluble calixarenes that form supramolecular complexes with uracils, including active pharmaceutical ingredients of 5-Fluorouracil and 5-Methyluracil drugs. Stability constants of the formed complexes in an aqueous-organic medium were determined by the HPLC method. The most favored structures of the calixarenes and their uracil complexes were optimized at the DFT level of approximation. In the most favored structures of all adducts, the uracil molecules coordinate via hydrogen bonding with the phosphorus-containing groups on the upper rim of the calixarene ligands.

Anionic complex of antamanide with the nitrate anion has been proven by electrospray ionization mass spectrometry (ESI-MS) method. Further, applying quantum chemical DFT calculations, the most probable structure of this complex was derived. The nitrate anion is embedded in the molecule of antamanide and its oxygens atoms are bonded by seven bonds to the hydrogen atoms of the ligand. Finally, the interaction energy, E(int), of the antamanide-NO₃⁻ complex was calculated as E(int) = -175.9 kJ/mol.

The present manuscript describes the synthesis, spectral characterisation, DFT studies and biological activity of a series of 3d transition metal complexes of (E)-2-((2-(benzo[d]thiazole-2-yl)hydrazono)methyl)-5-(diethylamino)phenol (L1) in (1:1) and (1:2) ratio. Various spectral analysis revealed the presence of ONN binding domain in L1. The elemental composition was confirmed using mass spectrometry technique. The stability of the geometry was also confirmed with DFT based method using B3LYP/LanL2Dz level of theory. Absence of any imaginary frequency revealed the presence of geometry on global minima of potential energy surface. Job’s plot confirm the stoichiometric ratio of metal complexes. Electrochemical behaviour (cyclic voltammetry), magnetic moment and Conductance measurements were also investigated for the metal-complexes. Kinetic parameters for different stages of thermal decomposition of metal complexes were calculated by using Coats–Redfern and Broido method. Positive free-energy of decomposition describes the non-spontaneous nature of thermal decomposition. The negative ΔS value observed for metal complexes under consideration reveals the ordered arrangement of metal complexes than their reactants. The octahedral environment of Co²⁺, Ni²⁺, Cu²⁺ and Cd²⁺ complexes was elucidated with the help of spectroscopic data. The ligand (L1) and its metal complexes (M1–M8) exhibited excellent α-amylase and moderate anti-oxidant activities. Maximum α-amylase inhibition was exhibited by M7 with a percentage inhibition of 96.65% (IC₅₀ = 0.070 µM) and the lowest by M1 (87.00%, IC₅₀ = 0.086 µM).

A new theoretical approach was recently addressed to predict cyclodextrin host–guest binding constants with the GFN2-xTB semiempirical quantum method. Within such a strategy, a set of starting supramolecular arrangements is automatically obtained through the UD-APARM software, and many optimized host–guest systems are used to obtain each binding constant. In the present work, within the scope of the multi-equilibrium treatment, we carried out a theoretical study concerning the host–guest systems formed with paraoxon (PRX), methyl-parathion (MPTN), and parathion (PTN) into α-cyclodextrin (α-CD), for which experimental data were addressed. Those guests correspond to pesticides in use, and their inclusion plays a role in remediation technology. The procedure for estimating binding constants for the host–guest system is discussed in terms of the ranges for the supramolecular parameters employed in exploring the GFN2-xTB Potential Energy Surface (PES). As a result, by investigating an unprecedented number of starting systems (3,076), we identified that proper exploration of the GFN2-xTB PES gives a reliable prediction of the binding constant in solution. Furthermore, with the study of different starting associations, for PTN/α-CD, we found an excellent linear correlation (R² = 0.987) between GFN2-xTB data and experimental information, which, as in our previous study, supports the discussed methodology for application in predicting binding constants for CD-based host–guest systems.

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A new indole-containing 2,6-pyridinedicarbohydrazide P3 was synthesized and well characterized employing NMR, ESI⁺-MS, FT-IR, and elemental analyses. The synthesized compound was examined as an efficient fluorescent turn-off and colorimetric cation receptor. The P3 receptor exhibited a remarkable rapid color change from colorless to brown in the presence of Cu²⁺ cations. P3 displayed selective fluorescence quenching and a UV-vis redshift only in the presence of Cu²⁺ ions. Job’s plot, NMR titration, and ESI⁺-MS data were used to determine the complex’s 1:2 stoichiometry between P3 and Cu²⁺. Fluorescence titration was used to calculate the association constant (K_a) as 2.9–3.5 × 10¹¹ M^− 2 and the limit of detection (LOD) as 4.2 × 10^− 9 M. P3-based test strips were developed, which might be used as a simple and effective Cu²⁺ test kit. DFT calculations were also performed to optimize the structures of the P3 and P3 + Cu²⁺ complex. This design will likely provide another avenue to develop chemosensors incorporating a functional group on the upper rim of the 2,6-pyridinedicarbohydrazide platform.

Tris(tetra-armed cyclen) with three cyclens linearly linked (1a) and pentakis(tetra-armed cyclen) with four cyclens linked to the central cyclen (1b) have been prepared. These structures of the ligands were confirmed by ¹H and ¹³C{¹H} NMR, CSI-MS, and elemental analysis. Upon addition of Ag⁺ to these novel ligands, we observed the formation of 1:1 to 1:3 (= 1a:Ag⁺) complexes and 1:1 to 1:5 (= 1b:Ag⁺) complexes, respectively, according to stoichiometry. The association constants for 1a and 1b with Ag⁺ using titration experiments with UV–vis spectroscopy were also estimated. Logβ₁, logβ₂, and logβ₃ of 1a were 6.4, 14, and 21, respectively, while logβ₁, logβ₂, logβ₃, logβ₄, and logβ₅ of 1b were 6.8, 13, 19, 24, and 29, respectively. The association constants obtained from experiments revealed that all cyclen units within the molecules formed complexes with Ag⁺ that exhibited nearly identical association constants. The result suggests that the ligands have a uniform binding affinity for Ag⁺ throughout their structures.

Benzimidazoles are known G-quadruplex binding molecules. G-quadruplex-selective binding is relevant in the target-based design of the molecules for treating certain diseases, including cancer. Herein, we present the synthesis of a new benzimidazolyl guanidine and its binding association with various nucleic acids viz., calf thymus DNA (duplex), kit22, myc22, and telo (G-quadruplexes). The synthesized compound is characterized by IR, NMR, and mass spectrometric techniques. The binding titration is carried out utilizing UV–vis and fluorescence spectroscopy. The conformational changes of DNAs on the ligand binding are monitored using circular dichroism. Further, the compound inclusion complex with a porphyrin-β-cyclodextrin host molecule. The binding strengths of the guanidine and its Ppy-CD inclusion complex are compared. The inclusion complexes bind stronger to G-quadruplexes than CT-DNA. The binding constants value is the largest for the interaction of the guanidine: porphyrin-β-cyclodextrin inclusion complex with the G-quadruplex kit22, which possesses a parallel conformation. The difference in the binding strengths is articulated and compared between duplex and G-quadruplex bindings.

This Review Article covers advances over the past two decades in the field of the organic modulation reactivity by supramolecular hosts. Specifically, the scope of this review is focused on some members of the cucurbit[n]urils (CB[n]) family. As we will show with different examples, the use of CB [6], CB [7] and CB [8] enables modification of the reactivity on a wide variety of reactions by their exceptional recognition properties in aqueous medium, adequate size, hydrophobic cavity and polarity portals. The first part of this review gives a brief discussion of the chemical properties of CB[n] relevant to understanding their effect on the reactivity of organic guests. Then, this article highlights two opposite effects: catalysis and inhibition processes based on the ability of CB[n] to modulate the chemical reactivity of representatives guests. Some examples of organic reactions, such as solvolysis, oxidation, isomerization, cicloaddition, among others, are discussed from a kinetic and thermodynamic point of view.