Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir-Blodgett films

Silver complexes of a cation binding supramolecular host, resorcinarene bis-crown (CNBC5) with propyl, nonyl, decyl and undecyl alkyl chains were investigated by NMR titration, picrate extraction and single crystal X-ray diffraction. Binding studies showed that both 1 : 1 and 1 : 2 (host-Ag(+)) complexes are present in solution with only a slight effect of the lower rim alkyl chain length on the binding constants (log K 4.0-4.2 for 1 : 2 complexes). Solid state complexes of the resorcinarene bis-crowns bearing either C(3) or C(11) chains were obtained. Single crystal X-ray analyses showed that both derivatives bind silver ions by metal-arene and Ag···O coordination from the crown ether bridges and from the solvent, and pack in layered or bilayered fashion. Furthermore, the amphiphilic nature of C11BC5 was demonstrated using the Langmuir balance technique. Langmuir-Blodgett films of the amphiphilic C11BC5-Ag complex were transferred onto a substrate and shown to possess antibacterial activity against E. coli.     

Effect of Laser Pulse Energy on the Characteristics of Cu Nanoparticles Produced by Laser Ablation Method in Acetone

The effect of laser fluence on the characteristics of Cu nanoparticles, prepared by laser ablation method, is investigated experimentally. 1–6 nm Cu nanoparticles were synthesized by the pulsed laser ablation of a high purity copper bulk in acetone. Effect of laser fluence on the size, morphology and structure of produced nanoparticles has been studied. Pulses of a Q-switched Nd:YAG laser of 1,064 nm wavelengths at 7 ns pulse width at different fluences was employed to irradiate the Cu target in acetone. The UV–Vis–NIR absorption spectra of nanoparticles exhibit surface plasmon resonance absorption peak in the visible region. TEM and SEM micrographs indicate that with increasing the laser fluence the average size of spherical Cu nanoparticles is decreased and only the sample which is produced with the highest fluence shows exceptional behavior. It is found that Cu nanoparticles exhibit photoluminescence emission with single peak due to its interband transition.     

Recent Progress on Biological Activity of Amaryllidaceae and Further Isoquinoline Alkaloids in Connection with Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive age-related neurodegenerative disease recognized as the most common form of dementia among elderly people. Due to the fact that the exact pathogenesis of AD still remains to be fully elucidated, the treatment is only symptomatic and available drugs are not able to modify AD progression. Considering the increase in life expectancy worldwide, AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. Due to their complex nitrogen-containing structures, alkaloids are considered to be promising candidates for use in the treatment of AD. Since the introduction of galanthamine as an antidementia drug in 2001, Amaryllidaceae alkaloids (AAs) and further isoquinoline alkaloids (IAs) have been one of the most studied groups of alkaloids. In the last few years, several compounds of new structure types have been isolated and evaluated for their biological activity connected with AD. The present review aims to comprehensively summarize recent progress on AAs and IAs since 2010 up to June 2021 as potential drugs for the treatment of AD.