covalent character
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2022 ◽  
pp. 1-16
Author(s):  
Ebrahim Balali ◽  
Sara Sandi ◽  
Masoome Sheikhi ◽  
Siyamak Shahab ◽  
Sadegh Kaviani

The adsorption of the Zejula drug on the surface of B12N12 nanocluster has studied using DFT and TD-DFT. The quantum calculations have performed at the M062X/6–311 + + G(d,p) level of theory in the solvent water. The adsorption of the Zejula from N13 atom on the B12N12 leads to the higher electrical conductivity due to the low Eg rather. The change of DM also displays a charge transfer between Zejula and nanocluster. The UV absorption and IR spectra were calculated. The adsorption of Zejula drug over B12N12 nanocluster in the complexes Zejula/B12N12 can be considered as a bathochromic shift. According to QTAIM analysis, -G(r)/V(r) values for B-O and B-N bonds confirming the electrostatic and partial covalent character. The values of LOL and ELF confirm that the interactions are dominated by electrostatic interaction contributions. The calculated data reveal the B12N12 nanocluster can be appropriate as a biomedical system for the delivery of Zejula drug.


2021 ◽  
Vol 18 ◽  
Author(s):  
Shamsa Sharifi ◽  
Masoome Sheikhi ◽  
Siyamak Shahab ◽  
Sadegh Kaviani ◽  
Rakesh Kumar

: The adsorption of the Lenalidomide (LNA) drug on the surface of the B12N12 nanocluster has been studied using DFT and TD-DFT calculations. The quantum calculations have been performed at the B3LYP/6-311+G** level of theory in the solvent water. The change of DM also displays a charge transfer between LNA and nanocluster. The adsorption of the LNA drug from the O1 atom on the B12N12 nanocluster leads to higher electrical conductivity due to the low Eg rather than the other active sites. According to QTAIM analysis, -G(r)/V(r) values for B-O and B-N bonds are between 0.5 and 1, confirming the partially covalent character. The values of LOL and ELF are low in the region between the nitrogen and oxygen atoms of LAN and B12N12, which show that the interactions have mainly non-covalent character. The calculated data revealed that the B12N12 nanocluster can be an appropriate biomedical carrier for the delivery of LNA drugs.


IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Valentina Milašinović ◽  
Krešimir Molčanov ◽  
Anna Krawczuk ◽  
Nikita E. Bogdanov ◽  
Boris A. Zakharov ◽  
...  

The variation of charge density of two-electron multicentre bonding (pancake bonding) between semiquinone radicals with pressure and temperature was studied on a salt of 5,6-dichloro-2,3-dicyanosemiquinone radical anion (DDQ) with 4-cyano-N-methylpyridinium cation (4-CN) using the Transferable Aspheric Atom Model (TAAM) refinement. The pancake-bonded radical dimers are stacked by non-bonding π-interactions. With rising pressure, the covalent character of interactions between radicals increases, and above 2.55 GPa, the electron density indicates multicentric covalent interactions throughout the stack. The experimental charge densities were verified and corroborated by periodic DFT computations. The TAAM approach has been tested and validated for atomic resolution data measured at ambient pressure; this work shows this approach can also be applied to diffraction data obtained at pressures up to several gigapascals.


2021 ◽  
Author(s):  
Peter Kraus

<div>In this work, I derive a set of formulas for calculating extrapolation parameters based on the percentage of HF exchange and PT correlation within the functional recipe. I use a set of CBS energies from finite element calculations, calculated with PBE and related functionals, to do so.<br></div><div>The obtained extrapolation parameters perform better than previous, empirically-derived values. They are shown to be transferrable to non-PBE functionals, and the [2,3]-zeta extrapolations work well in cases with non-covalent character.<br></div>


2021 ◽  
Author(s):  
Peter Kraus

<div>In this work, I derive a set of formulas for calculating extrapolation parameters based on the percentage of HF exchange and PT correlation within the functional recipe. I use a set of CBS energies from finite element calculations, calculated with PBE and related functionals, to do so.<br></div><div>The obtained extrapolation parameters perform better than previous, empirically-derived values. They are shown to be transferrable to non-PBE functionals, and the [2,3]-zeta extrapolations work well in cases with non-covalent character.<br></div>


2021 ◽  
Author(s):  
Peter Kraus

<div>In this work, I derive a set of formulas for calculating extrapolation parameters based on the percentage of HF exchange and PT correlation within the functional recipe. I use a set of CBS energies from finite element calculations, calculated with PBE and related functionals, to do so.<br></div><div>The obtained extrapolation parameters perform better than previous, empirically-derived values. They are shown to be transferrable to non-PBE functionals, and the [2,3]-zeta extrapolations work well in cases with non-covalent character.<br></div>


2021 ◽  
Vol 887 ◽  
pp. 201-206
Author(s):  
O.S. Sirotkin ◽  
Artem E. Buntin

The paper shows the possibility of using such quantitative characteristics of the element-oxygen chemical bond as the covalent character, metallic character and ionic character in substances to select a set of technological methods and develop a technology for nanomodification of natural bentonite aluminosilicates. The research results showed that thermal activation of bentonite at 200, 300, 380 and 400 °C with different modes of isothermal exposure (15, 30, 60, 120 minutes) does not significantly affect the efficiency of its modification with silicon (SS) and aluminum (AS) oxide nanoparticles, estimated by the increment of the compressive strength and the adsorption index for methylene blue. Obtaining a 46 % aqueous suspension of bentonite and modifying it with silicon and aluminum oxide nanoparticles followed by ultrasonic treatment after standing decreases the particle size by more than 4 times, which is a promising technological solution for improving the performance properties of ceramics, molding mixtures, adsorbents and other materials based on bentonite from various deposits.


2021 ◽  
Vol 45 (15) ◽  
pp. 6803-6810
Author(s):  
Naixin Zhang ◽  
Ailin Li ◽  
Congzhi Wang ◽  
Qunyan Wu ◽  
Jianhui Lan ◽  
...  

Actinide encapsulation can form chiral borospherenes, and the covalent character of An–B bonds dominates the formation of these actinoborospherenes.


2021 ◽  
Author(s):  
Atul D Sontakke ◽  
Arnoldus J van Bunningen ◽  
Sadakazu Wakui ◽  
Andries Meijerink

The covalent character of (oxy)nitrides has enabled tuning of emission color for new Eu2+- and Ce3+-doped phosphors and widespread implementation in white light LEDs. Mn2+-doped (oxy)nitrides form a relatively unexplored...


2020 ◽  
Author(s):  
Bin Sun ◽  
Amin morteza najarian ◽  
Chao Zheng ◽  
Laxmi Sagar ◽  
Min-Jae Choi ◽  
...  

Abstract Colloidal quantum dots (CQDs) are promising materials for IR light detection due to their tunable bandgap and solution processing; but to date, the time response of CQD IR photodiodes has been inferior to that provided by Si and InGaAs. We reasoned that the high permittivity of II-VI CQDs leads to slow charge extraction due to screening and capacitance; whereas III-Vs – if their surface chemistry could be mastered – offer a strong covalent character for low permittivity and fast operation. In initial studies, we found that existing covalent character led to imbalanced charge transport in InAs, the result of unpassivated surfaces and uncontrolled heavy doping. We report surface management using amphoteric ligand coordination and find that it addresses simultaneously the In and As surface dangling bonds. The new InAs CQD solids combine high mobility (0.04 cm2 V-1 s-1) with a 4x reduction in permittivity compared to PbS CQDs. The resulting photodiodes achieve a response time faster than 300 ps – a more than 100x improvement compared to the best previously-reported CQD photodiodes – combined with an external quantum efficiency (EQE) of 30% at 940 nm.


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