Frontier Molecular Orbital Calculations Research Articles

A Fluorescent and Colorimetric Chemosensor for Hg2+ Based on Rhodamine 6G With a Two-Step Reaction Mechanism.

A fluorescent and colorimetric chemosensor L based on rhodamine 6G was designed, synthesized, and characterized. Based on a two-step reaction, the chemosensor L effectively recognized Hg2+. The interaction between the chemosensor and Hg2+ was confirmed by ultraviolet–visible spectrophotometry, fluorescence spectroscopy, electrospray ionization–mass spectrometry, Fourier-transform infrared spectroscopy, and frontier molecular orbital calculations. The chemosensor L was also incorporated into test strips and silica gel plates, which demonstrated good selectivity and high sensitivity for Hg2+.

Conformers of 1,2,3,4 –tetrahydroisoquinoline in S0 and S1: An analysis through potential energy surface, hardness principles and vibrational spectroscopy

The conformational search for 1, 2, 3, 4-tetrahydroisoquinoline (THIQ) yields a number of conformers in S0 and S1 states. DFT calculations with different functionals along with ab-initio calculations indicate that the structure of the global minima in S0 strongly depends on basis sets and methods of calculation. The two close lying low energy conformers are the twisted ones with i) the axial position of NH and ii) equatorial position of NH. Their energy differs by 60 ± 30 cm−1 over all possible variations. The computed potential energy surfaces (PES) show three inequivalent minima in S0 and two in S1. Three transition states are found in S0 and two in S1. The twisted conformer with axial hydrogen (TA) is found to be the global minima in S1. The twisting angle for the optimized TA conformer is ∼31° in S0 and ∼32° in S1. The excited state is probed through CIS and TDDFT methods. The characteristic low-frequency vibrations appear at 93 cm−1 and 146 cm−1 in S0. The observed FT-IR spectra and the earlier observations in molecular beam experiments corroborate well with our calculated spectra. Frontier molecular orbital calculations associated with the electron density plots clearly identify the changes on the density on excitation. The calculated UV–Vis absorption spectra are explained with the help of these orbitals. Molecular electrostatic potential is calculated and the sites of eletrophilic interactions are noted. Hardnesses and electrophilicities are calculated for all the conformers to check their relative stability. The maximum hardness principle (MHP) is obeyed by the lowest energy conformer in DFT calculations with different functionals, but minimum electrophilicity principles (MEP) are not obeyed.

Synthesis, Spectroscopic Properties, Quantum Chemical Calculations, and Biological Activities of 2-{[5-(2-Fluorophenyl)-4-(4-methylphenyl)-4H-1,2,4-triazol-3-yl]sulfanyl}-1-[3-methyl-3-(2,4,6-trimethylphenyl)-cyclobutyl]ethan-1-one

2-{[5-(2-Fluorophenyl)-4-(4-methylphenyl)-4H-1,2,4-triazol-3-yl]sulfanyl}-1-[3-methyl-3-(2,4,6-trimethylphenyl)cyclobutyl]ethanone was synthesized and characterized by spectral techniques and quantum chemical calculations. The molecular geometry, vibrational frequencies, and gauge-including atomic orbital (GIAO) 1H and 13C NMR chemical shifts of the title compound in the ground state were calculated using the density functional method (B3LYP) with the 6–311G(d, p) basis set, and its electronic absorption spectra were calculated by the TD-DFT method based on the B3LYP/6-311G(d, p) level optimized structure in ethanol by using the PCM model. The calculated results showed that the optimized geometry well reproduces the theoretical vibrational frequencies, and the calculated chemical shifts were in a good agreement with the experimental values. The energetic behavior of the title compound was examined using the B3LYP method with the 6-311G(d, p) basis set in the framework of the Onsager and polarizable continuum model (PCM). In addition, DFT calculations of frontier molecular orbitals were carried out at the B3LYP/6-311G(d, p) level of theory. The title compound showed antibacterial and antioxidant activities at different levels.

Evaluating Adsorption of Proline Amino Acid on the Surface of Fullerene (C60) and Carbon Nanocone by Density Functional Theory

Determination of proline is of great importance and investigating the interaction of this amino acid with nanostructures play a key role in the construction of novel appropriate sensors for proline measurement. In this regard, proline adsorption on the surface of fullerene and carbon nanocone was studied by density functional theory. For this purpose, the structures of fullerene, nanocone, proline and proline-adsorbent complexes at two different configurations were optimized geometrically. Then, IR and Frontier molecular orbital calculations were done in the temperature range of 298.15-398.15 K at 10˚ intervals. The obtained adsorption energies, adsorption enthalpy changes, Gibbs free energy variations and thermodynamic equilibrium constants showed that the adsorption of proline on the surface of nanocone is exothermic, spontaneous, one sided and experimentally feasible. In this sense, proline adsorption on the fullerene is endothermic, non-spontaneous, balanced and experimentally impossible. The achieved specific heat capacity values reveal that carbon nanocone can be used in the development of thermal sensors for the determination of proline. The effect of temperature on the adsorption process was also checked out and the results indicate that 298.15 is the optimum temperature for the studied procedure. Some HOMO-LUMO parameters such as energy gap, electrophilicity, maximum charge capacity, chemical hardness and chemical potential were also evaluated. Accordingly, the findings demonstrate that carbon nanocone can be utilized in the electrochemical determination of proline.

Adsorption of Tetryl on the Surface of B12N12: A Comprehensive DFT Study

In this study, the adsorption of tetryl on the surface of boron nitride cage was evaluated by density functional theory. For this purpose, the structures of tetryl, B12N12, and the tetryl-B12N12 complexes were geometrically optimized. Then, IR and frontier molecular orbital calculations were performed on them. The calculated adsorption energies, Gibbs free energy changes (ΔGad), adsorption enthalpy changes (ΔHad) and thermodynamic equilibrium constants (Kth) revealed that the adsorption process of both explosives is experimentally feasible, spontaneous, exothermic and non-equilibrium. The specific heat capacity values (CV) showed that the heat sensitivity has been significantly reduced in the tetryl complexes with B12N12. The N-O and C-N bond lengths and the density values demonstrated that tetryl-derived products with boron nitride cage have higher explosive velocity and blasting pressure in comparison to the pure blasting materials without B12N12. The frontier molecular orbital parameters such as band gap, chemical hardness, electrophilicity, chemical potential and charge capacity were also studied and the results proved that boron nitride cage is an ideal electroactive sensing material in order to fabricate novel sensors for the determination of tetryl.

Synthesis, Experimental and Theoretical Characterization of 4-(((4-Ethyl-5-(Thiophene-2-yl)-4H-1,2,4-Triazol-3-yl)Thio)Methyl)-6-Methoxycoumarin

In this article 4-(((4-ethyl-5-(thiophene-2-yl)-4H-1,2,4-triazol-3-yl)thio)methyl)-6-methoxycoumarin compound (ETMM) has been synthesized and characterized both experimentally and theoretically. The synthesized compound was characterized experimentally by Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and Ultraviolet (UV) spectroscopic techniques. It was used Gaussian 09 software for theoretical calculations. Based on the theoretical data obtained was calculated the global reactivity descriptor of ETMM. Density Functional Theory (DFT) calculations of molecular electrostatic potentials and frontier molecular orbitals of ETMM were implemented at the B3LYP/6-311G(d,p) level of theory. It was observed that there was an excellent agreement between experimental NMR and calculated NMR data. R2 for 1HNMR and 13CNMR were computed as 0.992 and 0.993, respectively.

Synthesis and evaluation of antioxidant activity of some novel hydroxypyridinone derivatives: a DFT approach for explanation of their radical scavenging activity.

Background and purpose:Reactive oxygen species (ROSs) are continuously produced as byproducts of cell metabolism. Free radicals are an unstable form of ROSs with the tendency to react readily with biomolecules such as amino acids, lipids and DNA. These reactions lead to oxidative damages to the cell. Oxidative stress occurs when the concentration of the ROSs exceeds the capacity of antioxidative protection systems of the body. 5-Hydroxypyridin-4-one derivatives can chelate Fe2+ and Fe3+ due to their α-hydroxyketone moiety. Also, tautomerism in hydroxypyridinone ring leads to enough level of aromaticity resulting in a catechol-like behavior that provides them with good chelating and radical scavenging properties.Experimental approach:Different compounds were synthesized with 5-hydroxypyridine-4-one moiety as the core. The antioxidant properties of molecules were evaluated experimentally by DPPH scavenging method and theoretically using DFT/B3LYP with a 6-31++G (d,p) basis set. Electronic properties were investigated using frontier molecular orbital theory calculations. Furthermore, global descriptive parameters were obtained to find the chemical reactivity of molecules. The natural bond orbital analysis was performed to investigate charge distribution and hydrogen bonding.Findings/Results:Structures of the synthesized compounds were confirmed using IR, 1H-NMR, and 13C-NMR spectral analyses. Among all the synthesized compounds, Va and Vb showed the best antioxidant effect experimentally and computationally.Conclusion and implications:Results of this study were valuable in terms of synthesis, in silico, and in vitro antioxidant evaluations and can be useful for future investigations about the design of novel 5-hydroxypyridin- 4-one derivatives possessing iron-chelating and radical scavenging abilities.

A DFT and TD-DFT study on electronic structures and UV-spectra properties of octaethyl-porphyrin with different central metals(Ni, V, Cu, Co)

In this work, the octaethyl-porphyrins with different central metals (M-OEP, M = Ni, VO, Cu, Co) were used to investigate the ground-state molecular structure, electron distribution and UV-spectra properties on molecular level by density functional theory (DFT). The results showed that the calculation structure parameters of metalloporphyrins agreed well with the experimental value. According to the Natural Bond Orbital (NBO) analysis, the charge distribution of different metalloporphyrins was found that the charge values of the central metal M decreased with the order of VO < Ni < Co < Cu, while the bonding strength between M and the coordinating atom N was VO > Ni > Co > Cu. At the same time, the frontier molecular orbital calculations showed that the SOMO energy of VO (OEP) molecules in the open-shell system was higher than that of Co (OEP) and Cu (OEP), which means that its UV absorption characteristic peak would be red-shifted. In addition, the IEFPCM model of Time-dependent Density functional theory (TD-DFT) was further utilized to simulate the four substance in toluene solution: Co (OEP), Ni (OEP), Cu (OEP) and VO (OEP), and the Soret band peaks were calculated respectively as: 382 nm, 383 nm, 391 nm and 401 nm. Furthermore, the quantitative simulation analysis of metalloporphyrins was combined with experimental data. It could be found that the location rules of the four kinds of metalloporphyrins calculated absorption characteristic peaks were consistent with the experimental ones, and the relative errors of each peak were within 3%. These methods used above provide a theoretical path for analyzing and identifying unknown porphyrin compounds in petroleum.

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A new imidazole derivative, 2-(4-bromophenyl)-1-(3-fluoro-4-methylphenyl)-4,5-diphenyl-1H-imidazole (I) was synthesized and characterized by IR, Mass, NMR (1H and 13C), Single crystal X-ray diffraction, and elemental analysis techniques. Hirshfeld surface analysis was performed to find out the intercontacts in the crystal structure. Density functional theorem (DFT) based calculations viz. optimized geometry, frontier molecular orbital analysis and vibrational analysis were performed using Gaussian09 software at B3LYP functional and 6–31G* level basis set and compared with experimental values. The calculated geometric parameters are consistent with XRD data. Stability and charge transfer within the compound was explained by frontier molecular orbital calculations. Molecular electrostatic surface analysis revealed that positive potential is concentrated on the nitrogen atoms of the imidazole ring. Molecular docking of the compound to the active site of Candida albicans dihydrofolate reductase (PDB ID: 4HOE) revealed that the molecule is tightly bound to the target protein, with good docking score compared to standard ciprofloxacin.

Nucleophilic Substitution Reaction of Imidazole with Various 2-Bromo-1-arylethanone Derivatives: A Computational Study

In this study, it was intended to investigate the reactions between imidazole and 2-bromo-1-arylethanones such as 2-bromoacetophenone, 2-bromo-1-(4-chlorophenyl)ethan-1-one, 2-bromo-1-(2,4-dichlorophenyl)ethan-1-one and 2-bromo-1-(furan-2-yl)ethan-1-one, computationally. In the study, some Density Functional Theory (DFT) calculations have been performed on the chemical species involved in the investigated chemical reactions. DFT calculations have been performed at DFT B3LYP (Becke, three-parameter, Lee-Yang-Parr) level of theory using 6-31G(d), 6-31G(d,p), 6-311G(d,p) and 6-311+G(2d,p) basis sets. Single Point Energy (SPE) calculations, geometry optimizations, vibrational analysis, Frontier Molecular Orbital (FMO) calculations, global reactivity descriptor determinations, Molecular Electrostatic Potential (MEP) map calculations and estimation of the nuclear magnetic shielding tensors have been carried out at the same levels of theory. In 1H-NMR calculations, CSGT (Continuous Set of Gauge Transformations) and GIAO (Gauge-Independent Atomic Orbital) models were used and experimental data have been compared with the computationally obtained data.

Synthesis, characterization, DFT and molecular docking studies for novel 1,5-diphenylpenta-1,4-dien-3-one O-benzyl oximes

The main objectives of this study are: (a) to synthesize novel 1,5-diphenylpenta-1,4-dien-3-one O-benzyl oximes in an efficient way, (b) to investigate the synthesized molecules computationally via DFT calculations, (c) to compare computationally obtained data with experimental results and (d) to perform molecular docking calculations for the newly synthesized compounds and heat shock protein HSP90A N-terminal domain to determine the binding affinities of the investigated molecules and to reveal possible receptor–ligand interactions. In the first part of the study, syntheses and characterizations of the investigated compounds have been carried out. In this part, the target compounds have been synthesized and characterized successively. In the synthesis of target compounds from corresponding oximes, ultrasound has been used alternatively and results showed that the usage of ultrasound considerably increases the reaction rate and the efficiency. In the second part, detailed density functional theory calculations have been performed on the investigated compounds with the use of Becke, three-parameter, Lee–Yang–Parr hybrid functional and various basis sets. In this part, geometry optimizations, frequency analyses, NMR spectral analyses, frontier molecular orbital calculations, and molecular electrostatic potential map calculations have been performed. In NMR spectral analyses, both continuous set of gauge transformations (CSGT) and gauge-independent atomic orbital (GIAO) methods have been used and the obtained results with the use of various basis sets have been compared. Results showed that in NMR calculations, GIAO method is more successful than CSGT method and can provide satisfactory results even with small basis sets. In the third part of the study, molecular docking calculations have been performed on the investigated compounds and HSP90A N-terminal domain. Results showed that investigated molecules show a good binding affinity for HSP90A N-terminal domain. The binding affinities were found to be in the range of − 8.7 to − 10.1 kcal/mol.

Synthesis, X-ray crystal structure, Hirshfeld surface analysis, DFT, MESP and molecular docking studies of 2-(4-bromophenyl)-1-(3-fluoro-4-methylphenyl)-4,5-diphenyl-1H-imidazole

Abstract A new imidazole derivative, 2-(4-bromophenyl)-1-(3-fluoro-4-methylphenyl)-4,5-diphenyl-1H-imidazole (I) was synthesized and characterized by IR, Mass, NMR (1H and 13C), Single crystal X-ray diffraction, and elemental analysis techniques. Hirshfeld surface analysis was performed to find out the intercontacts in the crystal structure. Density functional theorem (DFT) based calculations viz. optimized geometry, frontier molecular orbital analysis and vibrational analysis were performed using Gaussian09 software at B3LYP functional and 6–31G* level basis set and compared with experimental values. The calculated geometric parameters are consistent with XRD data. Stability and charge transfer within the compound was explained by frontier molecular orbital calculations. Molecular electrostatic surface analysis revealed that positive potential is concentrated on the nitrogen atoms of the imidazole ring. Molecular docking of the compound to the active site of Candida albicans dihydrofolate reductase (PDB ID: 4HOE ) revealed that the molecule is tightly bound to the target protein, with good docking score compared to standard ciprofloxacin.

In vitro anti‐proliferative and in silico docking studies of heteroleptic copper(II) complexes of pyridazine‐based ligands and ciprofloxacin

Three heteroleptic copper(II) complexes of the type [Cu(L1–3)(cf)(ClO4)] (1–3), where cf = ciprofloxacin, have been synthesized using pyridazine‐based ligands 3‐chloro‐6‐(salicylidenehydrazinyl)pyridazine (HL1), 3‐chloro‐6‐(4‐diethylaminosalicylidenehydrazinyl)pyridazine (HL2) and 3‐chloro‐6‐(5‐bromosalicylidenehydrazinyl)pyridazine (HL3). Electronic spectral data and magnetic moment values suggest octahedral geometry for the synthesized copper(II) complexes. Electrochemical data of the copper(II) complexes present an irreversible one‐electron reduction wave in the cathodic potential region (Epc) between −0.631 and −0.670 V. Frontier molecular orbital calculations were carried out, and the obtained low‐energy gap supports the bio‐efficacy of the complexes. All the complexes were screened for their in vitro cytotoxicity activity against three human cancerous (breast adenocarcinoma (MCF‐7), hepatoma (HepG‐2) and cervical (HeLa)) and one non‐cancerous (non‐tumorigenic human dermal fibroblast (NHDF)) cell lines using MTT assay, in which complex 2 exhibited higher activity. The apoptosis induction by the complexes was analysed using the Hoechst dye staining method with MCF‐7 cell line, which indicates higher apoptotic activity of complex 2. A molecular docking study was carried out to ascertain the binding affinity of the synthesized heteroleptic copper(II) complexes with phosphoinositide 3‐kinase gamma (PI3Kγ) receptor.

Mechanistic Insight into Palladium‐Catalyzed Carbocyclization‐Functionalization of Bisallene: A Computational Study

AbstractDensity functional theory calculations were performed to reveal the mechanisms of Pd‐catalyzed cascade carbocyclization‐borylation and arylation reactions. The computational results indicate that the reactions start with allylic C−H cleavage through concerted metalation‐deprotonation and an intramolecular exo‐type allene insertion to form a six‐membered carbocycle intermediate. The regioselectivity of insertion could be explained by frontier molecular orbital theory and natural population analysis calculation. In the absence of extra nucleophiles, η1/η3‐isomerization followed by acetate‐assisted deprotonation could yield polyene product. When nucleophile was added to the reaction system, transmetalation and subsequent reductive elimination could give the exo‐substituted triene as major product. Meanwhile, η1/η3‐isomerization, transmetalation, and reductive elimination could afford the endo‐isomer as side product. The regioselectivity of further functionalization is controlled by the competition of transmetalation and η1/η3‐isomerization. The computational results show that both exo‐ and endo‐boronation product could be observed when bis(pinacolato)diboron is added as nucleophile. However, only exo‐phenylation product is observed when phenylboronic acid is used as nucleophile because of the high free‐energy barrier for reductive elimination from aryl η3‐allylic palladium.

Novel acyl thiourea derivatives: Synthesis, antifungal activity, gene toxicity, drug-like and molecular docking screening.

Nine novel acyl thioureas were synthesized. Their identities and purities were confirmed by LC-MS spectra; each structure was elucidated by elemental analysis, IR, 1 Н and 13 C NMR spectra. Applying an in vitro screening of their antifungal potential, three substances (3, 5, and 6) could be selected as showing high activity against 11 fungi and 3 Phytophthora strains of phytopathogenic significance. Analysis of gene toxicity with the Salmonella reverse mutagenicity test, as an assessment of drug likeness, lipophilicity, and calculations of frontier molecular orbitals assign a low toxicity profile to these compounds. Molecular docking studies point to 14α-demethylase (CYP51) and N-myristoyltransferase (NMT) as possible fungal targets for growth inhibition. The findings are discussed with respect to structure-activity relationship (SAR).

A Computational Study on the Nucleophilic Substitution Reaction between 2-Bromoacetophenone and Azole Derivatives

In this study, it was aimed to investigate the reaction of 2-bromoacetophenone with various azole derivatives, such as imidazole, benzimidazole, 1,2,4-triazole and benzotriazole computationally. For this purpose, some Density Functional Theory (DFT) calculations have been carried out on the reactants and products at B3LYP (Becke, three-parameter, Lee-Yang-Parr) level of theory using various basis sets, including 6-31G(d), 6-31G(d,p), 6-311G(d,p) and 6-311+G(2d,p). Geometry optimizations, Single Point Energy (SPE) calculations, frequency analysis, frontier molecular orbital calculations, molecular electrostatic potential (MEP) map calculations, and determination of global reactivity descriptors have been carried out at the same levels of theory. In NMR calculations, both Continuous Set of Gauge Transformations (CSGT) and Gauge-Independent Atomic Orbital (GIAO) methods have been used and computationally obtained data have been compared with the experimental data.

Sc2O@Cs(126339)-C92: Di-scandium oxide cluster encapsulated into a large fullerene cage

The geometric, electronic structure and thermodynamic stability of Sc2O@C92 has been characterized by using hybrid density functional theory calculations combined with statistical thermodynamic analyses. Results indicate that the isolated pentagon rule (IPR) isomers Sc2O@Cs(126339)-C92, Sc2O@C1(126367)-C92 and Sc2O@C1(126390)-C92 are favorable. Noteworthy, it is the first time to declare that fullerene isomer Cs(126339)-C92 could be considered as the suitable cage to encapsulate metallic cluster. The electronic properties of these three isomers were performed with frontier molecular orbital (HOMO and LUMO) analyses and bond order calculations. Finally, 13C NMR and UV-vis-NIR spectra were simulated to provide valuable information for future experiments.

Effects of styrene unit on molecular conformation and spectral properties of CN[sbnd]PhCH[dbnd]NPhCH[dbnd]CHPh[sbnd]CN

Compound CN-PhCH=NPhCH=CHPh-CN with both stilbene and benzylidene aniline units was synthesized, and studied from the viewpoint of molecular conformation and spectroscopic property by a combined use of experimental and computational methods. The maximum UV absorption wavelength (λmax) of the compound in ethanol, acetonitrile, chloroform and cyclohexane solvents were measured, and the 13C NMR chemical shift value δC(CN) in chloroform-d was determined. The crystal structure of the compound was determined by X-ray diffraction. The frontier molecular orbital was calculated by density functional theory method. The results show that the UV absorption spectrum of the titled compound is similar to those of Schiff bases, while there is a larger red shift of λmax comparing to that of CN-PhCH=NPh-CN. Moreover, the molecular configuration of the titled compound relative to CN is anti-form, having a more obvious twisted structure. The spectral and structural behaviors are further supported by the results of frontier molecular orbital analyses, NBO, electrostatic potentials and TD-DFT calculations. The study provides deeper insights into the molecular conformation of Schiff bases.

MOLECULAR DOCKING OF AMITRIPTYLINE TO CERULOPLASMIN, RETINOL-BINDING PROTEIN, AND SERUM ALBUMIN

Objective: A drug’s efficiency depends on the binding capacity of the drug with the particular plasma protein. The less bound drug can be easily diffused through cell membranes. The present study deals with in silico studies of amitriptyline binding to three plasma proteins human ceruloplasmin (HCP), cellular retinol-binding protein (CRBP), and human serum albumin (HSA) and tries to establish the binding capacity behavior with the frontier molecular orbital approach.Methods: Amitriptyline is selected as legend and docked with three plasma proteins HCP, HCP PDB ID 1KCW, CRBP PDB ID 5LJC, and HSA. Docking calculations were carried out using docking server. frontier molecular orbital calculations are performed through web-based computational chemistry interface WEBMO version 17.0.012e using server Buchhner.chem.hope.edu. on computational engine MOPAC.Results: HCP and HSA predominantly show polar and hydrophobic interactions, whereas CRBP forms hydrogen bond apart from polar and hydrophobic interactions. Favorable values of inhibition constant, Ki, is obtained which is equal to 1.13 μM for CRBP, 6.00 μM for HCP, and 2.00 μM for has.Conclusion: A studies prove that amitriptyline can bind to all three plasma proteins, namely, HCP, CRBP, and HSA. Amitriptyline binds to an HSA and HCP through polar and hydrophobic interactions while weak electrostatic interactions felicitate diffusion of amitriptyline through the plasma membrane. Comparatively, strong hydrogen bond in CRBP may make the bound drug to be released at a slow rate. Strong binding of amitriptyline to CRBP is also evident from the least value of inhibition constant, Ki, which is equal to 1.13 μM for CRBP, 6.00 μM for HCP, and 2.00 μM for has.

Determination of trace metal concentration in compost, DAP, and TSP fertilizers by neutron activation analysis (NAA) and insights from density functional theory calculations.

Leaching of toxic metals from fertilizers is a growing concern in an agricultural country like Bangladesh due to the serious consequences in health and food chain. Fertilizers used in farming fields and nurseries (plant sales outlet) in the mid-southern part of Bangladesh were collected for the determination of toxic metals. This study employed the neutron activation method and a relative standardization approach. Three standard/certified reference materials, namely NIST coal fly ash 1633b, IAEA-Soil-7, and IAEA-SL-1 (lake sediment), were considered for elemental quantification. Concentration of As (2.63-16.73mg/kg), Cr (40.93-261.77mg/kg), Sb (0.47-63.58mg/kg), Th (1.44-19.16mg/kg), and U (1.90-209.41mg/kg) were determined in fertilizers. High concentrations of Cr, Sb, and U were detected in some compost and phosphate fertilizers (TSP and diammonium phosphate (DAP)) in comparison with the IAEA/European market standard and other studies. Quantum mechanical calculations were performed to understand the molecular level interaction of CrO3, Sb2O3, and AsO3, with DAP by employing density functional theory with the B3LYP/SDD level of theory. Our results indicated that CrO3 and Sb2O3 have strong binding affinity with DAP compared to AsO3, which supports the experimental results. These compounds attached to the phosphate group through covalent-like bonding with oxygen. The frontier molecular orbital calculation indicated that HOMO-LUMO gap of the AsO3-DAP (5.46eV) and Sb2O3-DAP (6.48eV) complexes are relatively lower than the CrO3-DAP, which indicates that As and Sb oxides are chemically more prone to attach with the phosphate group of DAP fertilizer.