New trends in the chemistry of condensed heteromacrocycles Part A: Condensed azacrown ethers and azathiacrown ethers

Fabrication of Azacrown Ether-Embedded Covalent Organic Frameworks for Enhanced Cathode Performance in Aqueous Ni-Zn Batteries

Crown ethers (CEs), known for their exceptional host-guest complexation, offer potential as linkers in covalent organic frameworks (COFs) for enhanced performance in catalysis and host-guest binding. However, their highly flexible conformation and low symmetry limit the diversity of CE-derived COFs. Here, we introduce a novel C3-symmetrical azacrown ether (ACE) building block, tris(pyrido)[18]crown-6 (TPy18C6), for COF fabrication (ACE-COF-1 and ACE-COF-2) via reticular synthesis. This approach enables precise integration of CEs into COFs, enhancing Ni2+ ion immobilization while maintaining crystallinity. The resulting Ni2+-doped COFs (Ni@ACE-COF-1 and Ni@ACE-COF-2) exhibit high discharge capacity (up to 1.27 mAh ⋅ cm-2 at 8 mA ⋅ cm-2) and exceptional cycling stability (>1000 cycles) as cathode materials in aqueous alkaline nickel-zinc batteries. This study serves as an exemplar of the seamless integration of macrocyclic chemistry and reticular chemistry, laying the groundwork for extending the macrocyclic-synthon driven strategy to a diverse array of COF building blocks, ultimately yielding advanced materials tailored for specific applications.

Utility of 2-Chloro-N-arylacetamide and 1,1'-(Piperazine-1,4-diyl)bis(2-chloroethanone) as Versatile Precursors for Novel Mono- and Bis[thienopyridines]

A series of novel thieno[2,3-b]pyridines linked to N-aryl carboxamides or (carbonylphenoxy)-N-(aryl)acetamides, as well as bis(thieno[2,3-b]pyridines) linked to piperazine core via methanone or carbonylphenoxyethanone units, were synthesized by treating the appropriate chloroacetyl- or bis-bromoacetyl derivatives with 2-mercaptonicotinonitrile derivatives in ethanolic sodium ethoxide at reflux. The spectral data were used to determine the compositions of novel compounds.

Synthesis of Novel Diphenyl Ether-Based Bis-Heterocycles as Novel Hybrid Molecules via Michael and Other Cyclocondensation Reactions

Molecular hybridization is a technique used in drug creation that involves combining the pharmacophoric moieties of multiple bioactive compounds to create a new hybrid molecule with better affinity and effectiveness. In this regard, we created unique hybrid molecules out of diphenyl ether-linked fused pyrans and other heterocycles. The Michael reaction of 4,4'-oxydibenzaldehyde with malononitrile and various active methylene derivatives, as well as enaminone derivatives, produced the matching bis-fused pyrans and fused pyridines, both connected to a diphenyl ether moiety. Furthermore, the acid-catalyzed reaction of 4,4'-oxydibenzaldehyde with dimedone or β-naphthol produced the corresponding new bis(hexahydro-1H-xanthene-1,8-dione) and bis(14H-dibenzo[a,j]xanthene). The processes by which the target products are formed were also examined.

Synthesis and investigation of 3,5-bis-linear and macrocyclic tripeptidopyridine candidates by using l-valine,N,N′-(3,5-pyridinediyldicarbonyl)bis-dimethyl ester as synthon

Interest in the synthesis of heterocyclic organic molecules with peptide moieties has gained attention due to their potential biological activities. The current work aimed at synthesizing new macrocyclic tripeptide imides and evaluating their possible antimicrobial activities. A series of 11 derivatives were prepared from dimethyl 3,5-pyridinevalinyl ester either by NaOH or NH2NH2treatment, followed by cyclization and further reaction with NaOH or NH2NH2. The majority of synthesized derivatives showed promising antibacterial and antifungal activities in comparison to standard known antibiotics. Compounds5aand7bshowed the most potential antibacterial againstStaphylococcus aureusand antifungal activities againstCandida albicans, respectively.

Synthesis and biological activities of some new (Nα-dinicotinoyl)-bis-L-leucyl linear and macrocyclic peptides

A series of linear and macrocyclic peptides 3–12 were synthesized using 3,5-pyridinedicarboxylic acid (1) as starting material and screened for their antimicrobial, anti-inflammatory and anticancer activities. Bis-ester 3 was prepared from 1 and l-leucine methyl ester. Hydrazinolysis and hydrolysis of dipeptide methyl ester 3 with hydrazine hydrate or 1 N sodium hydroxide afforded compounds 4 and 5, respectively. Cyclization of the dipeptide 5 with l-lysine methyl ester afforded cyclic pentapeptide ester 6. Compounds 7–9 were synthesized by reacting hydrazide 4 with phthalic anhydride, 1,8-naphthalene anhydride or acetophenone derivatives. Treatment of acid hydrazide 4 with aromatic aldehydes or tetraacid dianhydrides afforded the corresponding bis-dipeptide hydrazones 10a–e and macrocyclic peptides 11 and 12, respectively. The structures of newly synthesized compounds were confirmed by IR, ¹H-NMR, MS spectral data and elemental analysis. The detailed synthesis, spectroscopic data, biological and pharmacological activities of the synthesized compounds was reported.

Synthesis of new macrocyclic polyamides as antimicrobial agent candidates

A series of macrocyclic imides and Schiff-bases have been prepared via the cyclocondensation of pyridine-2,6-dicarbonyl dichloride (1) with L-ornithine methyl ester to give the corresponding macrocyclic bisester 2. Treatment of 2 with hydrazine hydrate gave macrocyclic bisacid hydrazide 3, which was used as starting material. Condensation of bishydrazide 3 with diacid anhydrides or aromatic aldehydes in refluxing acetic acid or ethanol gave the corresponding macrocyclic bisimides 4, 5a,b and macrocyclic bis- hydrazones 6a–j, respectively. The structure assignments of the new compounds were based on chemical and spectroscopic evidence. The antimicrobial screening showed that many of these newly synthesized compounds have good antimicrobial activities, comparable to ampicillin and ketaconazole used as reference drugs.

Dibenzotetraaza Crown Ethers: A New Family of Crown Ethers Based on o-Phenylenediamine

Dibenzotetraaza (DBTA) crown ethers possess two o-phenylenediamine moieties. They are homologues of dibenzo crown ether phase-transfer catalysts and were prepared from the condensation of benzimidazoles with oligo(ethyleneglycol) dichlorides and oligo(ethyleneglycol) ditosylates. Compounds with ring sizes ranging from 18-crown-6 to 42-crown-14 were prepared. In addition, various altered benzimidizoles were used to produce DBTA crown ethers with modified substituents and ether bridges, as well as benzimidazolidine crown ethers. The synthetic approach presented here proved to be a convenient route to a new family of crown ethers with overall yields of up to 48% based on the benzimidazole. Yields for the ring-closing step were generally high, ranging from 51% to 94%, without the need for high-dilution conditions. Reaction of the DBTA crown ethers with alkyl and benzyl halides was found to be a facile way to obtain the corresponding tetra(N-organyl) compounds. Picrate extraction studies were carried out to determine phase-transfer catalytic capabilities. Extraction efficiencies for alkali-metal ions were lower than those for dibenzo-18-crown-6. Efficiencies were higher for other metal ions, with some selectivity for Pb(2+). Tetra(N-methyl) DBTA-18-crown-6 generally exhibited higher extraction efficiencies than its N-H analogue, but the selectivity was lower.