Papers by Dinh Hieu Truong
Surface enhanced Raman scattering (SERS) experiments and quantum chemical calculations (using den... more Surface enhanced Raman scattering (SERS) experiments and quantum chemical calculations (using density functional theory) on the interactions of chlorpyrifos (CPF), which is an intensively used pesticide, with roughed silver nanoparticle surface were thoroughly investigated to study the inherent molecular mechanism. Ligand-cluster interaction geometries show that the CPF molecule is mainly adsorbed on the silver surface via both S atom and pyridine ring involving a covalent Ag•••S coordination as well as van der Waals physisorption. Raman vibrational modes of CPF are centered at 474, 632, 678, 1277 and 1551 cm 1 characterizing the P-O-C bending, P=S stretching, Cl-ring mode and pyridine ring stretching, respectively, which are all enhanced when CPF is adsorbed on a silver surface. The concentration-dependent effect of CPF on silver substrates has been reproduced for the first time by coordinating 2 and 3 CPF molecules on an Ag 20 silver cluster model simulated by DFT computations. The intensities of the
Phytochemistry
Primary and secondary antioxidant activities of pyridoxal have been investigated by using density... more Primary and secondary antioxidant activities of pyridoxal have been investigated by using density functional theory (DFT) at the M05-2X level combined with 6-311++G(d,p) basis set for non-metallic atoms and LanL2DZ for metallic ions. The former has been examined by its free radical scavenging activity towards HOO●, HO●, and NO2●via different mechanisms including formal hydrogen transfer (FHT), proton transfer (PT), single electron transfer (SET), and radical adduct formation (RAF). The latter has been accomplished through its transition metal-chelating ability with Fe(III)/Fe(II) and Cu(II)/Cu(I) ions. The results show that pyridoxal illustrates as an efficient radical scavenger, especially, for HO● and NO2● in water. The overall rate constants (koverall) for the reactions with HOO●, HO●, and NO2● radicals are 1.30 × 104, 5.76 × 109, and 1.43 × 109 M-1s-1, respectively. The SET from the anionic state is the most dominant for the HOO● and NO2● scavenging reactions, while both RAF and SET contribute largely to the reaction with highly reactive HO● radicals. Moreover, the anionic form of pyridoxal demonstrates a better role as a metal chelator than the neutral. However, the pro-oxidant risks of the formed complexes could be observed if there are superoxide radical anion (O2●-) and ascorbate (Asc-) in aqueous media.
Vietnam Journal of Science and Technology
Phenolic acids are one of the major fractions identified in the extract of several vegetable seed... more Phenolic acids are one of the major fractions identified in the extract of several vegetable seed oils which present interesting antioxidant properties. A density functional theory (DFT) study on the antioxidant potential of eight phenolic acids including gallic, vanillic, isovanillic, ferulic, caffeic, b-coumaric, cinnamic, and chlorogenic acids, is presented in this paper. The bond dissociation enthalpies (BDEs) of C–H and O–H bonds, the proton affinities (PA) and the ionization energies (IEs) were calculated in detail by using the LC-wPBE functional coupled with the 6-311++G(d,p) basis set. The standard Gibbs free energies (DrG0) for the scavenging reactions towards HOO· radical were calculated. In addition, the kinetics of H-atom transfer reaction was evaluated. As a result, the chosen long-range corrected DFT LC-wPBE functional is shown as the highly reliable computational approaches in calculating geometrical properties as well as the thermochemical parameters by comparison wi...
Journal of molecular modeling, Jan 11, 2017
Understanding the physicochemical properties of corrosion inhibitors and their chemical interacti... more Understanding the physicochemical properties of corrosion inhibitors and their chemical interactions with metal surfaces is crucial to the design of improved (i.e., more efficient) corrosion inhibitors. In this work, the physicochemical properties of six thiophene-based corrosion inhibitors (2-acetylthiophene (AT), 2-formylthiophene (FT), thiophene (Th), 2-methyl-3-thiophenthiol (MTT), 2-pentylthiophene (PT), and 2-thenylthiol (TT)) were systematically studied by performing ab initio calculations at the MP2(full)/6-31G(2df,p) level of theory. Adsorption of the inhibitors on an iron surface was also modeled by investigating the interactions of these molecules with a tetrahedral Fe4 cluster using the B3LYP method and the 6-311G(d,p) basis set or the LanL2DZ basis set. The calculated results indicate that the nature of the substituent group present has a significant impact on the geometric and electronic structures of the thiophene-based molecules. The presence of an electron-donating ...
Vietnam Journal of Science and Technology
The surface-enhanced Raman scattering (SERS) phenomenon of 2,4,5-trichlorophenoxyacetic acid (2,4... more The surface-enhanced Raman scattering (SERS) phenomenon of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) adsorbed on Au20 pyramidal cluster is studied by Density Functional Theory. All possible adsorption configurations between the adsorbate and the Au20 clusters are evaluated and the vibrational assignments of normal Raman and SERS spectra are analyzed. The result shows that the most stable adsorption configuration of the adsorbate on Au20 cluster is formed by the interaction of O13 (-COOH group) and Au atom. The SERS activities of 2,4,5-T adsorbed on 1:1 Au-Ag and Au-Cu bimetallic clusters are also investigated. For bimetallic clusters, the substitution of 1, 4 or 10 Au atoms by Ag/Cu is performed by replacing the respective number of Ag/Cu atoms in 1, 2 and 3 parallel layers of the Au20 cluster. While the Raman scattering activity of the Au10Ag10 cluster is comparable to that of the Au20 cluster, it is remarkably higher than the Au10Cu10 cluster. This observation is explained by th...
The oxidation of L-proline (Pro) amino acid by HO● radical and the influence of transition metal ... more The oxidation of L-proline (Pro) amino acid by HO● radical and the influence of transition metal ions on this process have been investigated by using the density functional theory (DFT) method at the M05-2X/6-311++G(3df,3pd)//M05-2X/6-311++G(d,p) level of theory in the aqueous phase. The results show that Pro can be oxidized by HO● radical via formal hydrogen transfer (FHT) reactions at multiple sites, with the highest branching ratio found at hydrogen atoms H10 (30.04%) and H12 (25.60%). The overall rate constant at 298.15K is determined as 6.04 × 108 M-1 s-1, and its expression from 250 to 400K is k=1.634×T2.990×exp[1.591(kcal mol-1)/RT] M-1 s-1. In addition, Pro tends to form the stable mono- and bidentate complexes with both Fe and Cu ions via the–COO functional group of dipole-salt form, which significantly increases when the concentration of Pro doubles. The most stable Cu(II)-Pro complexes have high potential oxidant risks by enhancing the HO● radical formation when reducing ...
Royal Society Open Science
Hydroxyl radical (HO·) formation initiated by the Fenton-type reactions of Fe and Cu complexes of... more Hydroxyl radical (HO·) formation initiated by the Fenton-type reactions of Fe and Cu complexes of l -leucine (Leu) amino acid as well as its oxidation reaction by HO· was computationally investigated by using the density functional theory method at the M05-2X/6-311++G(3df,2pd)//M05-2X/6-311++G(d,p) level of theory in the aqueous phase. The results showed that dipole-salt is the main form of Leu in the physiological condition. Leu exhibits high chelating potential towards both Fe(III)/Fe(II) and Cu(II)/Cu(I) ions with the most favourable coordinating positions at two oxygen atoms of the –COO functional group. Furthermore, the Leu-ions complexes show a high risk of HO· formation via Fenton-like reactions, especially when ascorbate anion exists in the environment as a reducing agent. Finally, the oxidation reaction of l -leucine by HO· demonstrated a relatively high overall apparent reaction rate, k overall , being 1.18 × 10 9 M −1 s −1 , in which formal hydrogen transfer reactions of ...
RSC Advances, 2022
Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH3OO˙ radical s... more Direct and indirect antioxidant activities of rosmarinic acid (RA) based on HOO˙/CH3OO˙ radical scavenging and Fe(iii)/Fe(ii) ion chelation were theoretically studied using density functional theory at the M05-2X/6-311++G(2df,2p) level of theory.
Renewable Energy
The aim of this research is to develop an innovative approach for electric power conversion of th... more The aim of this research is to develop an innovative approach for electric power conversion of the vast ocean wave energy. A floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), which is shortened as HSTWEC, has been proposed to enhance the wave energy generation from wave fluctuations. In the HSTWEC device, the power takeoff system (PTO) was combined with an HST circuit and an electric generator to convert the mechanical energy generated by wave energy into electrical energy. Design concept and working principle of the HST circuit were firstly derived. Next, a mathematical model, control concepts and selections of main components of the HSTWEC system has been carried out for an adequate investigation of the suggested system. Finally, simulations using MATLAB/ Simulink and AMESim software have been performed in order to verify the effectiveness of the proposed HSTWEC. The simulation results show that more than 65% of wave energy can be absorbed by using the HSTWEC device.
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Papers by Dinh Hieu Truong