scholarly journals Stereochemistry of Simple Molecules inside Nanotubes and Fullerenes: Unusual Behavior of Usual Systems

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2437 ◽  
Author(s):  
Valerij Kuznetsov

Over the past three decades, carbon nanotubes and fullerenes have become remarkable objects for starting the implementation of new models and technologies in different branches of science. To a great extent, this is defined by the unique electronic and spatial properties of nanocavities due to the ramified π-electron systems. This provides an opportunity for the formation of endohedral complexes containing non-covalently bonded atoms or molecules inside fullerenes and nanotubes. The guest species are exposed to the force field of the nanocavity, which can be described as a combination of electronic and steric requirements. Its action significantly changes conformational properties of even relatively simple molecules, including ethane and its analogs, as well as compounds with C−O, C−S, B−B, B−O, B−N, N−N, Al−Al, Si−Si and Ge−Ge bonds. Besides that, the cavity of the host molecule dramatically alters the stereochemical characteristics of cyclic and heterocyclic systems, affects the energy of pyramidal nitrogen inversion in amines, changes the relative stability of cis and trans isomers and, in the case of chiral nanotubes, strongly influences the properties of R- and S-enantiomers. The present review aims at primary compilation of such unusual stereochemical effects and initial evaluation of the nature of the force field inside nanotubes and fullerenes.

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4539
Author(s):  
Nguyen Minh Thuy ◽  
Vo Minh ◽  
Tran Ben ◽  
My Tuyen Thi Nguyen ◽  
Ho Ha ◽  
...  

Butterfly pea flower have great sensory attraction, but they have not yet been used widely in Vietnam. Extracts of butterfly pea flowers can be used conveniently as a natural blue colorant for food products. In this study, the identification of anthocyanin compounds in butterfly pea flowers was performed by UPLC coupled with a UV and Mass spectrometer instrument. Positive and negative ion electrospray MS/MS chromatograms and spectra of the anthocyanin compounds were determined. By analyzing the chromatograms and spectra for each ion, five anthocyanins were identified in the butterfly pea flower extract; these were delphinidin-3-(6”‐p-coumaroyl)-rutinoside, cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl) glucose in both cis- and trans- isomers, cyanidin-3-(p-coumaroyl-glucoside) and delphinidin-3-pyranoside. Additionally, based on their intensity, it was determined that cyanidin-3-(p-coumaroyl-glucoside) was the most abundant anthocyanin, followed by cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl-glucoside), delphinidin-3-(6”-p-coumaroyl)-rutinoside and delphinidin-3-pyranoside. In this study, cyanidin derivatives were discovered in butterfly pea flower extract, where these compounds had not been detected in previous studies.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuta Saito ◽  
Shogo Hatayama ◽  
Yi Shuang ◽  
Paul Fons ◽  
Alexander V. Kolobov ◽  
...  

AbstractTwo-dimensional (2D) van der Waals (vdW) materials possess a crystal structure in which a covalently-bonded few atomic-layer motif forms a single unit with individual motifs being weakly bound to each other by vdW forces. Cr2Ge2Te6 is known as a 2D vdW ferromagnetic insulator as well as a potential phase change material for non-volatile memory applications. Here, we provide evidence for a dimensional transformation in the chemical bonding from a randomly bonded three-dimensional (3D) disordered amorphous phase to a 2D bonded vdW crystalline phase. A counterintuitive metastable “quasi-layered” state during crystallization that exhibits both “long-range order and short-range disorder” with respect to atomic alignment clearly distinguishes the system from conventional materials. This unusual behavior is thought to originate from the 2D nature of the crystalline phase. These observations provide insight into the crystallization mechanism of layered materials in general, and consequently, will be useful for the realization of 2D vdW material-based functional nanoelectronic device applications.


2020 ◽  
Vol 153 (24) ◽  
pp. 244308
Author(s):  
Ali Abou Taka ◽  
Mark C. Babin ◽  
Xianghai Sheng ◽  
Jessalyn A. DeVine ◽  
Daniel M. Neumark ◽  
...  

2011 ◽  
Vol 300 (6) ◽  
pp. H1990-H1996 ◽  
Author(s):  
Houli Jiang ◽  
John Quilley ◽  
Anabel B. Doumad ◽  
Angela G. Zhu ◽  
John R. Falck ◽  
...  

Epoxyeicosatrienoic acids (EETs) are vasodilator, natriuretic, and antiinflammatory lipid mediators. Both cis- and trans-EETs are stored in phospholipids and in red blood cells (RBCs) in the circulation; the maximal velocity ( Vmax) of trans-EET hydrolysis by soluble epoxide hydrolase (sEH) is threefold that of cis-EETs. Because RBCs of the spontaneously hypertensive rat (SHR) exhibit increased sEH activity, a deficiency of trans-EETs in the SHR was hypothesized to increase blood pressure (BP). This prediction was fulfilled, since sEH inhibition with cis-4-[4-(3-adamantan-1-ylureido)cyclohexyloxy]benzoic acid (AUCB; 2 mg·kg−1·day−1 for 7 days) in the SHR reduced mean BP from 176 ± 8 to 153 ± 5 mmHg ( P < 0.05), whereas BP in the control Wistar-Kyoto rat (WKY) was unaffected. Plasma levels of EETs in the SHR were lower than in the age-matched control WKY (16.4 ± 1.6 vs. 26.1 ± 1.8 ng/ml; P < 0.05). The decrease in BP in the SHR treated with AUCB was associated with an increase in plasma EETs, which was mostly accounted for by increasing trans-EET from 4.1 ± 0.2 to 7.9 ± 1.5 ng/ml ( P < 0.05). Consistent with the effect of increased plasma trans-EETs and reduced BP in the SHR, the 14,15- trans-EET was more potent (ED50 10−10 M; maximum dilation 59 ± 15 μm) than the cis-isomer (ED50 10−9 M; maximum dilation 30 ± 11 μm) in relaxing rat preconstricted arcuate arteries. The 11,12-EET cis- and trans-isomers were equipotent dilators as were the 8,9-EET isomers. In summary, inhibition of sEH resulted in a twofold increase in plasma trans-EETs and reduced mean BP in the SHR. The greater vasodilator potency of trans- vs. cis-EETs may contribute to the antihypertensive effects of sEH inhibitors.


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