scholarly journals A theoretical approach on the ability of functionalized gold nanoparticles for detection of Cd2+

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Khavani ◽  
Aliyeh Mehranfar ◽  
Mohammad Izadyar
Keyword(s):  
Gold Nanoparticles ◽  
Metal Ions ◽  
Functional Groups ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Md Simulations ◽  
Orbital Interactions ◽  
Donor Acceptor ◽  
The Stability ◽  
Functionalized Aunps

AbstractCadmium (Cd) as a toxic element that is widely present in water, soil, and air has important effects on human health, therefore proposing an accurate and selective method for detection of this element is of importance. In this article, by employing full atomistic molecular dynamics (MD) simulations and density functional theory dispersion corrected (DFT-D3) calculations, the effects of 6-mercaptonicotinic acid (MNA) and l-cysteine (CYS) on the stability of gold nanoparticles (AuNPs) and their sensitivity against Cd2+ were investigated. The obtained results indicate that pure AuNPs are not stable in water, while functionalized AuNPs with CYS and MNA groups have considerable stability without aggregation. In other words, the functional groups on the surface of AuNPs elevate their resistance against aggregation by an increase in the repulsive interactions between the gold nanoparticles. Moreover, functionalized AuNPs have considerable ability for selective detection of Cd2+ in the presence of different metal ions. Based on the MD simulation results, MNA-CYS-AuNPs (functionalized AuNPs with both functional groups) have the maximum sensitivity against Cd2+ in comparison with MNA-AuNPs and CYS-AuNPs due to the strong electrostatic interactions. DFT-D3 calculations reveal that the most probable interactions between the metal ions and functional groups are electrostatic, and Cd2+ can aggregate functionalized AuNPs due to strong electrostatic interactions with MNA and CYS groups. Moreover, charge transfer and donor–acceptor analyses show that molecular orbital interactions between the functional groups and Cd2+ can be considered as the driving force for AuNPs aggregation. A good agreement between the theoretical results and experimental data confirms the importance of the molecular modeling methods as a fast scientific protocol for designing new functionalized nanoparticles for application in different fields.

scholarly journals Phosphorene–Fullerene Nanostructures: A First-Principles Study

2021 ◽  
Author(s):  
Diego Cortes-Arriagada ◽  
Daniela E. Ortega
Keyword(s):  
Active Sites ◽  
Short Range ◽  
Density Functional ◽  
Dipole Moments ◽  
Molecular Size ◽  
Bandgap Engineering ◽  
Donor Acceptor ◽  
The Stability ◽  
Strong Repulsion ◽  
Intermolecular Distances

Hybrid materials formed by carbon fullerenes and layered materials have emerged due to their advantages for several technological applications, and phosphorene arises as a promising two-dimensional semiconductor for C60 adsorption. However, the properties of phosphorenefullerene hybrids remain mainly unexplored. In this work, we employed density functional theory to obtain structures, adsorption energies, electronic/optical properties, binding (AIM, NBO), and energy decomposition analyses (ALMO-EDA) of nanostructures formed by phosphorene and fullerenes (C24 to C70). We find fullerenes form covalent and non-covalent complexes with phosphorene depending on the molecular size, showing remarkable stability even in solution. Two classes of covalent complexes arise by cycloaddition-like reactions: the first class, where short-range effects (charge-transfer and polarization) determines the stability; and the second one, where short-range effects decay to avoid steric repulsion, and balanced longrange forces (electrostatics and dispersion) favors the stability. Otherwise, high-size fullerenes (C50 to C70) only form non-covalent complexes due to strong repulsion at shorter intermolecular distances and lack of dissociation barriers. In terms of electronic properties, fullerenes act as mild p-dopants for phosphorene, increasing its polar character and ability to acquire induced dipole moments (polarizability). Also, small energy-bandgap fullerenes (<0.8 eV) largely increase the phosphorene metallic character. We also note fullerenes retain their donor/acceptor properties upon adsorption, acting as active sites for orbital-controlled interactions and maximizing the phosphorene light absorbance at the UV-Vis region. Finally, we strongly believe our study will inspire future experimental/theoretical studies focused on phosphorene-fullerene uses for storage, anode materials, sensing, phosphorene bandgap engineering, and optoelectronics.<br>

THEORETICAL STUDY OF SANDWICH COMPLEXES [Fe(η4 - E4)2]2- (E = N, P, As, Sb, AND Bi)

2007 ◽  
Vol 06 (02) ◽  
pp. 363-376 ◽  
Author(s):  
ZHIWEI LI ◽  
CUNYUAN ZHAO ◽  
LIUPING CHEN
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Sandwich Complexes ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Orbital Interactions ◽  
The Stability ◽  
Equilibrium Geometries ◽  
Orbital Analysis ◽  
Iron Center

The equilibrium geometries, energies, harmonic vibrational frequencies, stability, and aromaticities for the [Formula: see text], E 4 Fe , and [ Fe (η4 - E 4)2]2- ( E = N, P, As, Sb, and Bi ) species are studied using density functional theory (DFT). The ground states of the E 4 Fe and [ Fe (η4 - E 4)2]2- systems are predicted to be Cs and D4d structures, respectively. Orbital analysis indicates that the orbital interactions between the π orbitals of the ligands and the atomic orbitals of the d 6 iron center are the main bonding scheme for these [ Fe (η4 - E 4)2]2- (D4d) complexes. The stability of the [ Fe (η4 - E 4)2]2- complexes exhibits the order P > As > Sb > Bi > N for E. On the basis of comparison with the known ferrocene, the NICS analysis confirms that the [ Fe (η4 - E 4)2]2- (D4d) as well as ferrocene are aromatic. The dissected NICS reveals that the aromaticities of the [ Fe (η4 - E 4)2]2- (D4d) are primarily attributed to the effects of their E–E π bonds and Fe lone pairs.

scholarly journals A Theoretical Study of the Adsorption Process of B-aflatoxins Using Pyracantha koidzumii (Hayata) Rehder Biomasses

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 283
Author(s):  
Abraham Méndez-Albores ◽  
René Escobedo-González ◽  
Juan Manuel Aceves-Hernández ◽  
Perla García-Casillas ◽  
María Inés Nicolás-Vázquez ◽  
...  
Keyword(s):  
Functional Groups ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Ph Value ◽  
Theoretical Calculations ◽  
Basis Set ◽  
Hydroxyl Group ◽  
Biosorption Process

Employing theoretical calculations with density functional theory (DFT) using the B3LYP/6-311++G(d,p) functional and basis set, the interaction of the aflatoxin B1 (AFB1) molecule and the functional groups present in the Pyracantha koidzumii biosorbent was investigated. Dissociation free energy and acidity equilibrium constant values were obtained theoretically both in solution (water) and gas phases. Additionally, the molecular electrostatic potential for the protonated molecules was calculated to verify the reactivity. Thus, methanol (hydroxyl group), methylammonium ion (amino group), acetate ion (carboxyl group), and acetone (carbonyl group), were used as representatives of the substrates present in the biomass; these references were considered using the corresponding protonated or unprotonated forms at a pH value of 5. The experimental infrared spectrophotometric data suggested the participation of these functional groups in the AFB1 biosorption process, indicating that the mechanism was dominated by electrostatic interactions between the charged functional groups and the positively charged AFB1 molecule. The theoretical determination indicated that the carboxylate ion provided the highest interaction energy with the AFB1 molecule. Consequently, an enriched biosorbent with compounds containing carboxyl groups could improve the yield of the AFB1 adsorption when using in vitro and in vivo trials.

Lithium Decorated Borane Clusters (BnHnLi6, n=5-7) as Promising Materials for Hydrogen Storage: A Computational Study

2021 ◽  
Author(s):  
Shakti S Ray ◽  
Sridhar Sahu
Keyword(s):  
Hydrogen Storage ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Md Simulations ◽  
Department Of Energy ◽  
Hydrogen Molecules ◽  
The Stability ◽  
Almost All

Abstract In this study, we have investigated the hydrogen adsorption potential of lithium decorated borane clusters (BnHnLi6, n = 5–7) using density functional theory calculations. The principle of maximum hardness and minimum electrophilicity confirmed the stability of the hydrogen adsorbed complexes. The outcomes of the study reveals that, the hydrogen molecules are adsorbed in a quasi-molecular fashion via Niu-Rao-Jena type of interaction with average adsorption energy falling in the range of 0.10-0.11eV/H2and average Li-H2 bond length is in the range of 2.436–2.550Å. It was found that the hydrogen molecules are physiosorbed at the host clusters at low temperature range 0K- 77K with gravimetric density up to 26.4 wt% which was well above target set by U.S. Department of Energy (US-DOE). ADMP-MD simulations showed that almost all the H2 molecules are desorbed at higher temperature form 373K-473K without distorting the host clusters which indicates the studied clusters can be promoted as promising reversible hydrogen storage

Can THF hydrogen bond to glycine as strong as water?

2017 ◽  
Vol 95 (6) ◽  
pp. 664-673 ◽  
Author(s):  
Damanjit Kaur ◽  
Geetanjali Chopra ◽  
Rajinder Kaur
Keyword(s):  
Hydrogen Bond ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Dominant Role ◽  
Basis Set ◽  
Hydrogen Bond Donor ◽  
Orbital Theory ◽  
Interaction Terms ◽  
Stability Of Complexes ◽  
The Stability

Hydrogen bond complexation between glycine and THF and between glycine and water involving four lowest-energy glycine conformers have been studied. The complexes have been investigated in the gas phase at the ab initio molecular orbital theory (MP2) with aug-cc-pVDZ basis set and density functional theory (B3LYP) with aug-cc-pVTZ basis set. Bader’s theory of atoms in molecules (AIM), natural bond orbital (NBO), and symmetry adapted perturbation theory (SAPT) analyses are employed to elucidate the interaction characteristics in the complexes. The premise that the hydrogen bond donor ability of the O–H group of the carboxyl group dominates the interaction between glycine and THF and between glycine and water is confirmed. It is found that in comparison with water, THF binds more strongly to glycine. The quantum studies indicate that contribution of N–H···O and C–H···O hydrogen bonds in the complexes, although lower in magnitude to O–H···O interactions, play an important role in the stability of complexes. The blue and red shifts in the stretching frequencies of the hydrogen bond donors X–H (X = O, C, N) have also been related to stabilization energies. Decomposition of the stabilization energy based on the SAPT method clearly indicates the dominant role of the electrostatic interactions in all the complexes under study; however, induction and dispersion interaction terms are relatively higher in glycine–THF complexes.

scholarly journals Epoxy Resins and their Zinc Composites as Novel Anti-Corrosive Materials for Copper in 3% Sodium Chloride Solution: Experimental and Computational Studies

2020 ◽  
Vol 2 (2) ◽  
pp. 40-41
Keyword(s):  
Epoxy Resins ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
Md Simulations ◽  
Corrosion Current ◽  
Metallic Surface ◽  
Computational Studies ◽  
Functional Theory ◽  
Donor Acceptor ◽  
Phosphoric Triamide

The evaluation the anticorrosive performance of two macromolecular aromatic epoxy resins (ERs), namely, tetra glycidyl of ethylene dianiline (TGEDA), hexaglycidyl Tris (p-Ethylene Dianiline) Phosphoric Triamide (HGEDPAT), and their polymer composite reinforced with Zinc for copper corrosion in 3% NaCl by means of computational and experimental analyses. Anticorrosive property of the standards and composites was demonstrated using experimental and computational methods. Electrochemical results showed that HGEDAPT cured with methylene dianiline (MDA) showed better protection efficiency with optimum corrosion current density (icorr) value of 2.0 µcm-2 and the polarization resistance (Rp) value of 17,00 kΩ.cm2 than that of TGEDA-MDA having icorr value of 2.4 µcm-2 and the Rp value of 15.24 kΩ.cm2. The anticorrosive effect of TGEDA-MDA and HGEDAPT-MDA was evaluated in the presence of 5% zinc (Zn). Experimental results demonstrate that the presence of 5% of zinc in TGEDA-MDA and HGEDAPT-MDA formulations significantly enhanced their protection ability. The anticorrosive effect of different formulations followed the order: ER1 (TGEDA-MDA) (potentiodynamic polarization (PDP); 90% and electrochemical impedance spectroscopy (EIS) 92%) < ER2 (HGEDAPT-MDA) (PDP; 92% and EIS 93%) < ER3 (TGEDA-MDA-5%Zn) (PDP; 96% and EIS 97%) < ER4 (HGEDAPT-MDA-5%Zn) (PDP; 97% and EIS 98.5%). Density Functional Theory (DFT) study revealed that ER1 and ER2 interact with the metallic surface using donor-acceptor interactions in which electron-rich centers acted as the most favorable sites for the interactions. Molecular dynamics (MD) simulations studies suggest that ER1 and ER2 acquire flat or horizontal orientations, and their orientations on the metallic surface are largely influenced by the presence of zinc. Different experimental and computational studies are in good agreement.

scholarly journals Density Functional Theory Analysis of Poly Glycolic Acid with Metal Ions (Na+, K+) Interaction

2019 ◽  
Vol 9 (1S3) ◽  
pp. 366-369
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
Glycolic Acid ◽  
Carbonyl Oxygen ◽  
Chemical Hardness ◽  
Binding Affinities ◽  
Functional Theory ◽  
Fukui Functions ◽  
The Stability

The complexation between Poly glycolic acid (PGA) and alkali metal ions (Na+ , K+ ) have been studied using B3LYP/6-311++G** method. The binding site of metal ion interaction on PGA is carbonyl oxygen. Both metal ions form bidendate complexation with PGA. Further, it can be noted that the PGA with K+ complex is more stable than the PGA with Na+ complex. The binding affinities (ΔH), basicity (ΔG) and the complexation entropies (ΔS) of all the studied systems are calculated. The interaction energy is maximum in PGA-Na+ than the PGA-K + complex. This is due to more charge transfer taking place between PGA and Na. The stability of the complex is studied by the chemical hardness value. The condensed Fukui functions are calculated and are used to predict the favourable reactive site

scholarly journals Phosphorene–Fullerene Nanostructures: A First-Principles Study

2021 ◽  
Author(s):  
Diego Cortes-Arriagada ◽  
Daniela E. Ortega
Keyword(s):  
Active Sites ◽  
Short Range ◽  
Density Functional ◽  
Dipole Moments ◽  
Molecular Size ◽  
Bandgap Engineering ◽  
Donor Acceptor ◽  
The Stability ◽  
Strong Repulsion ◽  
Intermolecular Distances

Hybrid materials formed by carbon fullerenes and layered materials have emerged due to their advantages for several technological applications, and phosphorene arises as a promising two-dimensional semiconductor for C60 adsorption. However, the properties of phosphorenefullerene hybrids remain mainly unexplored. In this work, we employed density functional theory to obtain structures, adsorption energies, electronic/optical properties, binding (AIM, NBO), and energy decomposition analyses (ALMO-EDA) of nanostructures formed by phosphorene and fullerenes (C24 to C70). We find fullerenes form covalent and non-covalent complexes with phosphorene depending on the molecular size, showing remarkable stability even in solution. Two classes of covalent complexes arise by cycloaddition-like reactions: the first class, where short-range effects (charge-transfer and polarization) determines the stability; and the second one, where short-range effects decay to avoid steric repulsion, and balanced longrange forces (electrostatics and dispersion) favors the stability. Otherwise, high-size fullerenes (C50 to C70) only form non-covalent complexes due to strong repulsion at shorter intermolecular distances and lack of dissociation barriers. In terms of electronic properties, fullerenes act as mild p-dopants for phosphorene, increasing its polar character and ability to acquire induced dipole moments (polarizability). Also, small energy-bandgap fullerenes (<0.8 eV) largely increase the phosphorene metallic character. We also note fullerenes retain their donor/acceptor properties upon adsorption, acting as active sites for orbital-controlled interactions and maximizing the phosphorene light absorbance at the UV-Vis region. Finally, we strongly believe our study will inspire future experimental/theoretical studies focused on phosphorene-fullerene uses for storage, anode materials, sensing, phosphorene bandgap engineering, and optoelectronics.<br>

The stability of graphene-based Möbius strip with vacancy and at high-temperature

2018 ◽  
Vol 32 (31) ◽  
pp. 1850350
Author(s):  
Kaishuai Yang ◽  
Chuanguo Zhang ◽  
Xiaohong Zheng ◽  
Xianlong Wang ◽  
Zhi Zeng
Keyword(s):  
Density Functional ◽  
Md Simulations ◽  
Melting Behavior ◽  
Stable Configuration ◽  
Möbius Strip ◽  
Functional Theory ◽  
Melting Temperatures ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Mobius Strip

The structural and electronic properties of mono-vacancy (MV) defect in graphene-based Möbius strip (GMS) are studied in the framework of density functional theory (DFT) combined with the molecular dynamics (MD) simulations. Two kinds of MV defects are observed: the 59-type MV (a configuration with one pentagon and one nonagon ring) located at the curved areas of Möbius strip, and the 5566-type MV (a configuration with two pentagon and two hexagon rings) with one sp3 hybridized carbon appeared in the twisted areas. The 5566-type MV defect is the most stable configuration at 0 K, while the DFT-MD calculations show that it is unstable at room-temperature and will transform into a 59-type MV. Additionally, the melting behavior of GMSs is investigated through empirical potential MD simulations, and we find that their melting temperatures are about 2750 K, which is lower than that of carbon nanotubes and graphene.

Functional gold nanoparticles for sensing applications

2013 ◽  
Vol 2 (3) ◽  
pp. 269-288 ◽  
Author(s):  
Guomei Zhang
Keyword(s):  
Heavy Metal ◽  
Gold Nanoparticles ◽  
Metal Ions ◽  
Surface Functionalization ◽  
Heavy Metal Ions ◽  
Catalytic Properties ◽  
Smart Sensors ◽  
Sensing Applications ◽  
New Generation ◽  
Functionalized Aunps

AbstractNanoparticle-based technologies have played important roles in providing opportunities for the development of a new generation of sensing tools. Because of their unique optical, chemical, electrical, and catalytic properties, gold nanoparticles (AuNPs) have been extensively studied for biological and chemical detections as well as analytical applications. AuNP-based sensors are expected to change the foundations of sensing and detecting biomolecules and metal ions. The ease of surface functionalization of AuNPs allows chemists to create the desired functionalities for specific applications. In this review, we will discuss the use of surface-functionalized AuNPs for fabricating smart sensors that are capable of detecting heavy metal ions, glucose, and specific biomolecules such as protein and DNA.

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