Unconventional approaches for chiral resolution.

Chirality is a fundamental and ubiquitous property of nature involved in multiple fields of science. In particular, the possible resolution of the enantiomeric forms of a molecule is crucial in the pharmaceutical, food, and agrochemical industries. The search for efficient, broad-spectrum, and yet simple methods for obtaining enantiomerically pure substances is a current challenge. Enantioselective resolution methods rely on an asymmetric environment that allows the two antipodes of a chiral molecule to be distinguished. In addition to enantiomeric separation techniques, such as chromatography and electrophoresis, new promising approaches involving out-of-the-scheme synergistic effects between chiral selectors (CS) and external stimuli are emerging. This Trends article discusses different enantioselective mechanisms triggered by unconventional physicochemical stimuli for the design of avant-garde approaches that could offer novel perspectives in the field of chiral resolution.

Inherently Chiral Oligomers Based on Indole-Benzothiophene Core.

In recent years, transductors of chiral information based on conducting polymers have gained considerable attention. In particular, inherently chiral materials, which allow differentiation between the antipodes of a chiral analyte in terms of energetic variations, are highly desired. In this work, we successfully synthesized a novel inherently chiral oligomer based on an indole-benzothiophene core, namely, 2-([2,2'-bithiophen]-5-yl)-3-(2-([2,2'-bithiophen]-5-yl)benzo[b]thiophen-3-yl)-N-methylindole (BTIndT4). The electrochemical characterization evidences a stabilization of electrogenerated radical cations due to the presence of the indole group, which guides the oligomerization, producing well-ordered polymeric matrices. Furthermore, the in situ electrochemical conductance analysis demonstrates a simultaneous intrachain and interchain transfer of charge carriers. Finally, the highly efficient enantiorecognition capabilities of the antipodes of the oligo-BTIndT4 films toward the enantiomers of tryptophan and 3,4-dihydroxyphenylalanine (DOPA), as model chiral analytes, were demonstrated.

Wireless asymmetric umpolung electrosynthesis.

Electroorganic synthesis has become an exciting tool for the asymmetric conversion of pro-chiral compounds. Herein, we introduced a wireless methodology based on bipolar electrochemistry in synergy with the enantioselective capabilities of inherently chiral oligomers to induce an umpolung chirality transfer. This was exemplified by the electro-conversion of a racemic mixture of lansoprazole to an enantio-enriched solution of a single antipode.

Adaptive 2D and Pseudo-2D Systems: Molecular, Polymeric, and Colloidal Building Blocks for Tailored Complexity.

Two-dimensional and pseudo-2D systems come in various forms. Membranes separating protocells from the environment were necessary for life to occur. Later, compartmentalization allowed for the development of more complex cellular structures. Nowadays, 2D materials (e.g., graphene, molybdenum disulfide) are revolutionizing the smart materials industry. Surface engineering allows for novel functionalities, as only a limited number of bulk materials have the desired surface properties. This is realized via physical treatment (e.g., plasma treatment, rubbing), chemical modifications, thin film deposition (using both chemical and physical methods), doping and formulation of composites, or coating. However, artificial systems are usually static. Nature creates dynamic and responsive structures, which facilitates the formation of complex systems. The challenge of nanotechnology, physical chemistry, and materials science is to develop artificial adaptive systems. Dynamic 2D and pseudo-2D designs are needed for future developments of life-like materials and networked chemical systems in which the sequences of the stimuli would control the consecutive stages of the given process. This is crucial to achieving versatility, improved performance, energy efficiency, and sustainability. Here, we review the advancements in studies on adaptive, responsive, dynamic, and out-of-equilibrium 2D and pseudo-2D systems composed of molecules, polymers, and nano/microparticles.

Gold-oxoborate nanocomposite-coated orthodontic brackets gain antibacterial properties while remaining safe for eukaryotic cells.

The study's main objective is to limit bacterial biofilm formation on fixed orthodontic appliances. Bacterial biofilm formation on such devices (e.g., brackets) causes enamel demineralization, referred to as white spot lesions (WSL). WSL is significant health, social and economic problem. We provide a nanotechnology-based solution utilizing a nanocomposite of gold nanoparticles embedded in a polyoxoborate matrix (BOA: B-boron, O-oxygen, A-gold, Latin aurum). The nanocomposite is fully inorganic, and the coating protocol is straightforward, effective, and ecologically friendly (low waste and water-based). Prepared coatings are mechanically stable against brushing with a toothbrush (up to 100 min of brushing). Bacteria adhesion and antibacterial properties are tested against Streptococcus mutans-common bacteria in the oral cavity. BOA reduces the adhesion of bacteria by around 78%, that is, from around 7.99 × 105  ± 1.33 × 105  CFU per bracket to 1.69 × 105  ± 3.07 × 104  CFU per bracket of S. mutans detached from unmodified and modified brackets, respectively. Modified fixed orthodontic brackets remain safe for eukaryotic cells and meet ISO 10993-5:2009 requirements for medical devices. The gathered data show that BOA deposited on orthodontic appliances provides a viable preventive measure against bacteria colonization, which presents frequent and significant complications of orthodontic treatment.

Heteroaggregation of virions and microplastics reduces the number of active bacteriophages in aqueous environments.

The objective of this study is to explore the effects of microplastics on the viability of the bacteriophages in an aqueous environment. Bacteriophages (phages), that is, viruses of bacteria, are essential in homeostasis. It is estimated that phages cause up to 40% of the death of all bacteria daily. Any factor affecting phage activity is vital for the whole food chain and the ecology of numerous niches. We hypothesize that the number of active phages decreases due to the virions' adsorption on microplastic particles or by the released leachables from additives used in the production of plastic, for example, stabilizers, plasticizers, colorants, and reinforcements. We exposed three diverse phages, namely, T4 (tailed), MS2 (icosahedral), and M13 (filamentous), to 1 mg/mL suspension of 12 industrial-grade plastics [acrylonitrile butadiene styrene, high-impact polystyrene, poly-ε-caproamide, polycarbonate, polyethylene, polyethylene terephthalate, poly(methyl methacrylate), polypropylene, polystyrene, polytetrafluoroethylene, polyurethane, and polyvinyl chloride] shredded to obtain microparticles of radius ranging from 2 to 50 µm. The effect of leachables was measured upon exposure of phages not to particles themselves but to the buffer preincubated with microplastics. A double-overlay plaque counting method was used to assess phage titers. We employed a classical linear regression model to verify which physicochemical parameters (65 variables were tested) govern the decrease of phage titers. The key finding is that adsorption mechanisms result in up to complete scavenging of virions, whereas leachables deactivate up to 50% of phages. This study reveals microplastic pollution's plausible and unforeseen ecotoxicological effect causing phage deactivation. Moreover, phage transmission through adsorption can alter the balance of the food chain in the new environment. The effect depends mainly on the zeta potentials of the polymers and the phage type.

Azahomofullerenes as New n-Type Acceptor Materials for Efficient and Stable Inverted Planar Perovskite Solar Cells.

Fullerene derivatives with a strong electron-accepting ability play a crucial role in enhancing both the performance and stability of perovskite solar cells (PSCs). However, most of the used fullerene molecules are based on [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which limits the device performance due to difficulties in preparing high-quality and uniform thin films. Herein, solution-processable azahomofullerene (AHF) derivatives (abbreviated as AHF-1 and AHF-2) are reported as novel and effective electron-transport layers (ETLs) in p-i-n planar PSCs. Compared to the control PCBM ETL-based PSCs, the devices based on AHFs exhibit higher photovoltaic performances, which is attributed to the enhanced charge-transport properties and improved layer morphology leading to a maximum power conversion efficiency (PCE) of 20.21% in the case of the device based on AHF-2 ETL. Besides, due to the preferable energy band alignment with the perovskite layer, reduced trap states, and suppressed charge recombination, the device with AHF-2 ETL exhibits significantly suppressed hysteresis and improved stability under both ambient and thermal conditions.