scholarly journals Positional Effect of π-extension in Triple Helicenes

2021 ◽  
Author(s):  
Alex van der Ham ◽  
Hermen S. Overkleeft ◽  
Dmitri V. Filippov ◽  
Grégory F. Schneider
Keyword(s):  
Optical Properties ◽  
Nmr Spectroscopy ◽  
Rational Design ◽  
Marked Effect ◽  
Chemical Properties ◽  
Positional Effect ◽  
Physico Chemical ◽  
Optical Applications ◽  
High Level ◽  
Vt Nmr

Application of multiple helicenes in photo‐optical applications requires their rational design. We therefore here report on the synthesis of pyrene‐based triple helicene 1, to study the positional effect of extension of the π‐conjugated system on the photo‐chemical and chiro‐optical properties of triple helicenes. The conformational and aggregatory behavior of 1 were studied both experimentally using VT NMR spectroscopy and computationally using high‐level DFT computations. Although π‐extension was observed to have a marked effect on the spectroscopy properties of triple helicenes, comparison with other known π‐extended helicenes reveals that the position at which π‐extension is introduced is only of nominal importance. Our results thus suggest that the presence of a particular helicene motive is dominant in dictating the physico‐chemical properties of triple helicenes.

scholarly journals Positional Effect of π-extension in Triple Helicenes

2021 ◽  
Author(s):  
Alex van der Ham ◽  
Thomas Hansen ◽  
Hermen S. Overkleeft ◽  
Trevor A. Hamlin ◽  
Dmitri V. Filippov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Rational Design ◽  
Marked Effect ◽  
Chemical Properties ◽  
Spectroscopic Properties ◽  
Positional Effect ◽  
Physico Chemical ◽  
Optical Applications ◽  
High Level ◽  
Vt Nmr

The targeted application of multiple helicenes in photo-optical applications requires their rational design. Toward this goal, we report on the synthesis of pyrene-based triple helicene 1 and investigate the positional effect of extension of the π-conjugated system on the photo-chemical and chiro-optical properties of triple helicenes. The conformational and aggregatory behavior of 1 were studied both experimentally using VT NMR spectroscopy and computationally using high-level DFT computations. Although π-extension was observed to have a marked effect on the spectroscopic properties of triple helicenes, comparison with other known π-extended helicenes reveals that the position at which π-extension is introduced is only of nominal importance. Our results thus suggest that the presence of a particular helicene motif is dominant in dictating the physico-chemical properties of triple helicenes.

Efficient Assessment of Physico-Chemical Properties of the Cryolite Melts for Research on the Improvement of Low-Temperature Aluminum Electrolysis

2018 ◽  
Vol 284 ◽  
pp. 839-844 ◽  
Author(s):  
V.A. Lebedev ◽  
Andrey A. Shoppert
Keyword(s):  
Low Temperature ◽  
Chemical Properties ◽  
Aluminum Electrolysis ◽  
Total Power ◽  
Potassium Cryolite ◽  
High Magnitude ◽  
Rate Of Dissolution ◽  
Physico Chemical ◽  
Hazardous Production ◽  
High Level

Modern aluminum electrolysis in cryolite-alumina melts is energy-intensive, inefficient and environmentally hazardous production. Addressing these significant shortcomings, the technology of low-temperature electrolyte is directed. The basis of low-temperature electrolysis is potassium cryolite, which results in high magnitude and rate of dissolution of alumina. Additive of sodium and lithium fluorides provide the necessary conductivity. Experimental investigation of these properties is extremely time consuming. In this work, as a parameter, which will allow to characterize effectively and rapidly the complexing ability of cryolite melts, the ratio of cationic ion power of Al3+ to the total power of the other cations of the melt is proposed. Regression analyses of the known experimental data establish the existence with a high level of reliability (R2=0.966-0.995) of a directly proportional dependence of this parameter on solubility of alumina and electrical conductivity of cryolite melts.

scholarly journals Use of Organosilicon Compounds towards the Rational Design of Antiparasitic and Antiviral Drugs

1995 ◽  
Vol 2 (3) ◽  
pp. 143-151 ◽  
Author(s):  
Gérard Déléris
Keyword(s):  
Reverse Transcriptase ◽  
Antisense Oligonucleotides ◽  
Rational Design ◽  
Chemical Properties ◽  
Therapeutic Agents ◽  
Main Group ◽  
Biologically Active ◽  
Hiv Reverse Transcriptase ◽  
Antiparasitic Drugs ◽  
High Level

One of the major problems met for the conception of antiviral or antiparasitic drugs is to reach a high level of selectivity towards the pathogenic agent versus the host. We shall describe two synthetic approaches where main group organometallics have been used towards this goal. A series of nucleoside sila-analogues was synthesized as potential therapeutic agents designed to inhibit HIV Reverse Transcriptase. In a second approach novel organosilicon derivatives have been synthesized as mimics of antisense oligonucleotides.Infectious agents, namely viruses or parasites, more or less use cellular machinery. Therefore therapeutic agents must interfere with biochemical mechanisms or possess high affinity towards specific molecular cellular components, to reach selectivity.We thought that main group organometallics could show many advantages for designing biologically active molecules in this field. They allow a high synthetic flexibility for the modulations of physico-chemical properties and they show a mechanistic behaviour which may be close to the one of several heteroelements present in living organisms such as sulfur or phosphorus.We tried to use this approach towards two directions involving the synthesis of organosilicon derivatives i.e:-the synthesis of organosilicon derivatives as inhibitors of HIV Reverse Transcriptase,-the synthesis of organosilicon precursors of modified antisense oligonucleotides.

scholarly journals Metal Chalcogenides Based Heterojunctions and Novel Nanostructures for Photocatalytic Hydrogen Evolution

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 89 ◽  
Author(s):  
Jian Li ◽  
Pablo Jiménez-Calvo ◽  
Erwan Paineau ◽  
Mohamed Nawfal Ghazzal
Keyword(s):  
High Performance ◽  
Rational Design ◽  
Individual Component ◽  
Chemical Properties ◽  
Charge Carriers ◽  
Metal Chalcogenides ◽  
Physico Chemical ◽  
Efficient Charge ◽  
Periodical Structure ◽  
Hollow Cylinders

The photo-conversion efficiency is a key issue in the development of new photocatalysts for solar light driven water splitting applications. In recent years, different engineering strategies have been proposed to improve the photogeneration and the lifetime of charge carriers in nanostructured photocatalysts. In particular, the rational design of heterojunctions composites to obtain peculiar physico-chemical properties has achieved more efficient charge carriers formation and separation in comparison to their individual component materials. In this review, the recent progress of sulfide-based heterojunctions and novel nanostructures such as core-shell structure, periodical structure, and hollow cylinders is summarized. Some new perspectives of opportunities and challenges in fabricating high-performance photocatalysts are also discussed.

scholarly journals Ichthyofaunal Diversity and Physico-Chemical Factors of Melamchi River, Sindhupalchok, Nepal

2016 ◽  
Vol 21 (1) ◽  
pp. 10-18
Author(s):  
Abha R. Mishra ◽  
Chitra Bahadur Baniya
Keyword(s):  
Fish Species ◽  
Fish Community ◽  
Diversity Index ◽  
Chemical Properties ◽  
Habitat Characteristics ◽  
Fish Diversity ◽  
Physico Chemical ◽  
Chemical Factors ◽  
High Level

The fish community and physico-chemical properties at five sites of Melamchi River were studied monthly from January 2011 to December 2013.    Melamchi River is one of tributaries larger Indrawati River basin, originates from the high snowy Jugal Mountain (5,875 m asl). Eleven fish species within two orders and five families were recorded.   Cypriniformes  was  found  to  be  the  most  dominant  order  with  ten  fish  species. Schizothorax plagiostomus  was the most common fish species followed by  Neolissochilus hexagonolepis, and  Psilorhynchus pseudecheneis.  Shannon Wiener fish diversity index and species richness recorded were highest at site 2 and lowest at site 5, whereas, evenness index was highest at site 3. The cluster analysis revealed  that  similarity  between  fish  species  decreased  as  the  distance  between  the  sites  increased.  Fish species were found distributed among four groups with respect to the significant habitat characteristics in the redundancy analysis (RDA). River water was found well-oxygenated and alkaline at all sites. However, high level for turbidity (43.25/ NTU) was observed at site 5, which exceeded compliance levels of WHO indicating the influence of intensive agriculture and deforestation along river area. To improve fish diversity and water quality of this river proper monitoring and management are an urgent need.Journal of Institute of Science and TechnologyVolume 21, Issue 1, August 2016, Page: 10-18

scholarly journals A voltage-dependent fluorescent indicator for optogenetic applications, archaerhodopsin-3: Structure and optical properties from in silico modeling

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 33 ◽  
Author(s):  
Dmitrii M. Nikolaev ◽  
Anton Emelyanov ◽  
Vitaly M. Boitsov ◽  
Maxim S Panov ◽  
Mikhail N. Ryazantsev
Keyword(s):  
Optical Properties ◽  
Rational Design ◽  
Molecular Design ◽  
Hybrid Approach ◽  
Three Dimensional ◽  
Membrane Voltage ◽  
Dimensional Structure ◽  
Fluorescent Indicators ◽  
Voltage Dependent ◽  
High Level

It was demonstrated in recent studies that some rhodopsins can be used in optogenetics as fluorescent indicators of membrane voltage. One of the promising candidates for these applications is archaerhodopsin-3. However, the fluorescent signal for wild-type achaerhodopsin-3 is not strong enough for real applications. Rational design of mutants with an improved signal is an important task, which requires both experimental and theoretical studies. Herein, we used a homology-based computational approach to predict the three-dimensional structure of archaerhodopsin-3, and a Quantum Mechanics/Molecular Mechanics (QM/MM) hybrid approach with high-level multireference ab initio methodology (SORCI+Q/AMBER) to model optical properties of this protein. We demonstrated that this methodology allows for reliable prediction of structure and spectral properties of archaerhodopsin-3. The results of this study can be utilized for computational molecular design of efficient fluorescent indicators of membrane voltage for modern optogenetics on the basis of archaerhodopsin-3.

Some physico-chemical properties of porcine milk

1975 ◽  
Vol 42 (1) ◽  
pp. 43-56 ◽  
Author(s):  
M. C. T. Hoynes ◽  
P. F. Fox
Keyword(s):  
Bovine Milk ◽  
Chemical Properties ◽  
Complete Removal ◽  
Heat Stability ◽  
Rennet Coagulation ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
High Level ◽  
Ph Curve ◽  
Porcine Milk

SummaryThe principal results of an investigation of the major physico-chemical properties of porcine milk were:Heat stability: all individual porcine milks examined had poor heat stability and some coagulated in 2 min at 95°C; the Q10°C was high and variable and was 40 for some samples. Dialysis of porcine milk against bulk bovine milk did not influence its heat stability; removal of colloidal calcium phosphate (CCP) from porcine milk increased its heat stability 4-fold, but it was still very unstable. Unlike bovine milk, porcine milk did not exhibit a maximum-minimum in the heat stability-pH curve, but rather resembled bovine casein micelles suspended in milk dialysate. Addition of isolated bovine β-lactoglobulin to porcine milk did not influence its heat stability-pH curve.Rennet coagulation: under similar conditions, porcine milk coagulated about 4 times faster than bovine milk and the resultant curd was about twice as soft. Dialysis of porcine milk against a large excess of bulk bovine milk did not influence its rennet coagulability nor did removal of 50% of its CCP, but complete removal of the CCP rendered porcine milk non-coagulable by rennin. Porcine milk was readily coagulated by rennin down to 5°C; its second-stage coagulation was independent of temperature – a characteristic due mainly to its high level of CCP.Alcohol stability: porcine milk was coagulated by 66–68% (v/v) ethanol, as compared with 74% (v/v) for bovine milk.Calcium stability: porcine milk was stable to at least 300 mM-CaCl2 at both 2 and 37°C.Solvation: porcine milk contained significantly less water of hydration than bovine milk, 1·7g H2O/g casein compared with 2·0g H2O/g casein.

scholarly journals 1H NMR spectroscopy study of structural water in rehydrated biocomposite of Spongilla lacustris freshwater demosponge origin

2020 ◽  
Vol 126 (8) ◽  
Author(s):  
Tatiana Krupska ◽  
Marcin Wysokowski ◽  
Iaroslav Petrenko ◽  
Yuliya Khrunyk ◽  
Krzysztof Nowacki ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Properties ◽  
Model Systems ◽  
Spectroscopy Study ◽  
Structural Water ◽  
H Nmr ◽  
Physico Chemical ◽  
History Of ◽  
Model Drug ◽  
Scientific Attention

Abstract Biocomposites of sponge origin attract scientific attention due to their renewability as well as special properties. Dried skeletons of fresh water demosponge Spongilla lacustris represent unique kind of naturally occurring silica-chitin-based biocomposites with long history of their applications in dermatocosmetics. However, there is still a lack of knowledge on their physico-chemical properties in model systems. The aim of this work was to model drug systems based on S. lacustris powdered biocomposite, water and a hydrophobic medium, which served as an analog of an oil base. Both thermogravimetric analysis and 1H NMR spectroscopy study of structural water in rehydrated biocomposite lead to obtaining of interesting experimental data useful for preparation of biocosmetic products.

scholarly journals Synthesis, physic and chemical properties of 2-(4-R-5-(thiophene-2-ylmethyl)-4h-1,2,4-triazole-3-ylthio)acetate acids and their salts

2018 ◽  
pp. 48-54
Author(s):  
O. A. Suhak ◽  
О. I. Panasenko ◽  
Ye. G. Knysh
Keyword(s):  
Biological Activity ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Chemical Properties ◽  
Biological Action ◽  
Biologically Active ◽  
Physico Chemical ◽  
Methods Of Synthesis ◽  
Medicinal Drugs

Derivatives of 1,2,4-triazole are inherent in various types of biological activity. They can be used as pesticide and medicinal drugs (anticonvulsants, analgetics, antitumor and antibacterial). In this regard the search of new methods of synthesis and investigation of biological activity of 2-(4-R-5-(thiophene-2-ylmethyl)-4H-1,2,4-triazole-3-ylthio)acetate acids and their salts is relevant nowadays. With the aim of finding the new biologically active compounds 2-(4-R-5-(thiophene-2-ylmethyl)-4H-1,2,4-triazole-3-ylthio)acetate acids and their salts are synthesized, where R is methyl, ethyl, phenyl. The interaction of 4-R-5-(thiophene-2-ylmethyl)-4H-1,2,4-triazole-3-thions with monochloracetate acid in the medium of i-propyl alcohol in the presence of an equivalent amount of alkali the corresponding 2-(4-R-5-(thiophene-2-ylmethyl)-4H-1,2,4 triazole-3-ylthio)acetate acids are obtained on the basis of which the corresponding salts of morpholine, dimethylamine, monoethanolamine, pteridine, ZnSO4 , CuSO4, NaOH and KOH are obtained and the structure of the received compounds was confirmed on the basis of the data of elemental, IR-, 1H-NMR-spectroscopy. The synthesis of 2-(4-R-5-(thiophene-2-ylmethyl)-4H-1,2,4-triazole-3-ylthio) acetate acids and their salts was conducted. With the help of modern physico-chemical methods: elemental analysis, IR, 1H-NMR-spectroscopy the structure of synthesized compounds, and their individuality by HPLC-MS is proved. In the IR spectrum of the compound 2-(4-phenyl-5-(thiophene-2-ylmethyl)-4H-1,2,4-triazole-3-ylthio)acetate acid Ic available band fluctuations groups characteristic for the nucleus of 1,2,4-triazole: NH– in the range of 3 400–3 100 cm-1,–C=N– – 1 690–1 620 cm-1. Also present band fluctuations groups –C–S– at 691 cm-1. Available band fluctuations characteristic of the group –CH2 within 1496.59 cm-1 and group –COO-H– – 1722.70 cm-1. This suggests the possibility to further study the biological action of the synthesized compounds.

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