scholarly journals Physicochemical, antioxidant properties of carotenoids and its optoelectronic and interaction studies with chlorophyll pigments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruby Srivastava
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Antioxidant Properties ◽  
Visible Region ◽  
State Theory ◽  
Chemical Hardness ◽  
Functional Theory

AbstractThe physicochemical and antioxidant properties of seven carotenoids: antheraxanthin, β-carotene, neoxanthin, peridinin, violaxanthin, xanthrophyll and zeaxanthin were studied by theoretical means. Then the Optoelectronic properties and interaction of chlorophyll-carotenoid complexes are analysed by TDDFT and IGMPLOT. Global reactivity descriptors for carotenoids and chlorophyll (Chla, Chlb) are calculated via conceptual density functional theory (CDFT). The higher HOMO–LUMO (HL) gap indicated structural stability of carotenoid, chlorophyll and chlorophyll-carotenoid complexes. The chemical hardness for carotenoids and Chlorophyll is found to be lower in the solvent medium than in the gas phase. Results showed that carotenoids can be used as good reactive nucleophile due to lower µ and ω. As proton affinities (PAs) are much lower than the bond dissociation enthalpies (BDEs), it is anticipated that direct antioxidant activity in these carotenoids is mainly due to the sequential proton loss electron transfer (SPLET) mechanism with dominant solvent effects. Also lower PAs of carotenoid suggest that antioxidant activity by the SPLET mechanism should be a result of a balance between proclivities to transfer protons. Reaction rate constant with Transition-State Theory (TST) were estimated for carotenoid-Chlorophyll complexes in gas phase. Time dependent Density Functional Theory (TDDFT) showed that all the chlorophyll (Chla, Chlb)–carotenoid complexes show absorption wavelength in the visible region. The lower S1–T1 adiabatic energy gap indicated ISC transition from S1 to T1 state.

SOLVENT EFFECTS ON THE ELECTRONIC STRUCTURE AND NON-LINEAR OPTICAL PROPERTIES OF PYRENE AND SOME OF ITS DERIVATIVES BASED ON DENSITY FUNCTIONAL THEORY

2021 ◽  
Vol 4 (4) ◽  
pp. 236-251
Author(s):  
A. S. Gidado ◽  
L. S. Taura ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Lumo Energy ◽  
Functional Theory ◽  
Organic Optoelectronic ◽  
Homo Lumo

Pyrene (C16H10) is an organic semiconductor which has wide applications in the field of organic electronics suitable for the development of organic light emitting diodes (OLED) and organic photovoltaic cells (OPV). In this work, Density Functional Theory (DFT) using Becke’s three and Lee Yang Parr (B3LYP) functional with basis set 6-311++G(d, p) implemented in Gaussian 03 package was  used to compute total energy, bond parameters, HOMO-LUMO energy gap, electron affinity, ionization potential, chemical reactivity descriptors, dipole moment, isotropic polarizability (α), anisotropy of polarizability ( Δ∝) total first order hyper-polarizability () and second order hyperpolarizability (). The molecules used are pyrene, 1-chloropyrene and 4-chloropyrene  in gas phase and in five different solvents: benzene, chloroform, acetone, DMSO and water. The results obtained show that solvents and chlorination actually influenced the properties of the molecules. The isolated pyrene in acetone has the largest value of HOMO-LUMO energy gap of and is a bit closer to a previously reported experimental value of  and hence is the most stable. Thus, the pyrene molecule has more kinetic stability and can be described as low reactive molecule. The calculated dipole moments are in the order of 4-chloropyrene (1.7645 D) < 1-chloropyrene (1.9663 D) in gas phase. The anisotropy of polarizability ( for pyrene and its derivatives were found to increase with increasing polarity of the solvents.  In a nutshell, the molecules will be promising for organic optoelectronic devices based on their computed properties as reported by this work.

A Density Functional Theory Study on the Structures and Electronic Properties of XAln (X = Br, I; n = 3–15) Clusters

2019 ◽  
Vol 74 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Ming Hui ◽  
Qing-Huai Zhao ◽  
Zhi-Peng Wang ◽  
Shuai Zhang ◽  
Gen-Quan Li
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Three Dimensional ◽  
Density Functional Theory Calculations ◽  
Chemical Hardness ◽  
Geometrical Structures ◽  
Functional Theory ◽  
The Density Functional Theory

AbstractThe effects of halogen element X (X = Br, I) doping on the geometrical structures and electronic properties of neutral aluminium clusters are systematically studied by utilising the density functional theory calculations. The structures of X-doped clusters show the three-dimensional forms with increasing atomic number except for n = 3 and X (X = Br, I) atom prefer to occupy the surface site of the host Aln clusters. BrAl7 and IAl7 clusters are the most stable geometries. The HOMO-LUMO energy gap and chemical hardness show an odd–even alternative phenomenon. The charges always transfer from the Al atoms to the X (X = Br, I) atom. Finally, the dipole and polarisability are discussed.

scholarly journals A Computational Study of Optoelectronic and Charge Transport Properties of Purine Nucleobases Dinucleotides Compounds

2021 ◽  
Author(s):  
Kimberly Madison ◽  
Wojciech Kolodziejczyk ◽  
Karina Kapusta ◽  
Glake Hill
Keyword(s):  
Density Functional Theory ◽  
Charge Transport ◽  
Transport Properties ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Computational Study ◽  
Blue Shift ◽  
Functional Theory ◽  
Vertical Excitation

Abstract Optoelectronic and charge transport properties of eight novel compounds are presented in this work. Density functional theory B3LYP was utilized to optimize all structures while time-dependent density functional theory was utilized for vertical excitation characteristics. Gas and solvent phases (water, THF, and DCM) were evaluated to gain insight on solid-state and solution processed devices. While the solvent phases enhanced most of the charge transport properties, there was seen a blue-shift in their absorption wavelengths. However, C2, C4, C6, and C8 in THF absorption maxima were the highest and similar to those of the gas phase (605-652 nm). Extension of the polymer size decreased the HOMO-LUMO gap energy with C7 having the lowest energy gap in the gas phase. Although tuning the properties in optoelectronic devices is challenging, these findings will assist with the design of higher quality materials that could surpass the quality of inorganic devices.

scholarly journals Density Functional Theory Investigation of the Doping Effects of Bromine and Fluorine on the Electronic and Optical Properties of Neutral and Ionic Perylene

2021 ◽  
pp. 1-13
Author(s):  
Auwal A. Abubakar ◽  
A. B. Suleiman ◽  
A. S. Gidado
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Hardness ◽  
Functional Theory ◽  
Bond Lengths ◽  
Hybrid Molecules ◽  
Non Linear ◽  
Linear Optical Properties

Perylene and its derivatives are some of the promising organic semiconductors. They have found vast applications in many areas such as photovoltaic systems, organic light-emitting diodes, and so on. The instability of organic molecules under ambient conditions is one factor deterring the commercialization of organic semiconductor devices. Currently, most of the investigation of Perylene and its derivatives concentrated on its diimide and bisimide derivatives. In this work, an investigation of the effects of doping Bromine and Fluorine on the electronic and non-linear optical properties was carried out based on Density Functional Theory (DFT) as implemented in the Gaussian 09 software package. We computed the Molecular geometries of the molecules, HOMO-LUMO energy gap, global chemical indices and non-linear optical properties using the same method. The bond lengths and angles of the mono-halogenated molecules at different charge states were found to be less than that of the isolated Perylene. 1-fluoroperylene was found to be the most stable amongst the studied molecule for having the least bond angles and bond lengths. In the calculation of the energy bandgap neutral 1-fluoroperylene was observed to have the highest energy gap 3.0414 eV and 3.0507 eV for 6-31++G(d,p) and 6-311++G(d,p) basis sets respectively. These results were found to agree with the existing literature. This reconfirmed 1-fluoroperylene as the most stable molecule. The computations of the ionic molecules reported small values of the energy gap. The molecule with the most chemical hardness was obtained to be the neutral 1-fluoroperylene with a chemical hardness of 1.5253eV. All the ionic molecules results were found to be more reactive than their neutral form for having lower values of chemical hardness. For NLO calculations, the results showed an increment in their values with the ionic hybrid molecules having the largest values.  In the case of first-order hyper-polarizability, 1-bromoperylene (neutral), 1-fluoroperylene (neutral), 1-bromoperylene (anionic), 1-fluoroperylene (anionic), 1-bromoperylene (cationic) and 1-fluoroperylene (cationic) were found to be 73.93%, 1.71%, 83.9%, 39.2%,38.7% and 41.7% larger than that of Urea respectively. These calculated results make these hybrid molecules suitable for a wide range of optoelectronic applications.

scholarly journals Density Functional Theory Calculation of Molecular Descriptors for Simple Coumarins in Gas and Different Solvents

2020 ◽  
Vol 32 (10) ◽  
pp. 2545-2552
Author(s):  
Poodari Sumalatha ◽  
Mannam Subbarao
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Theoretical Calculations ◽  
Density Functional Theory Calculation ◽  
Log P ◽  
Full Geometry Optimization ◽  
Functional Theory ◽  
Functional Density Theory

The primary aim of this study is to show the importance of molecular structure analysis of pharmaceutical active coumarins compounds using quantum chemistry methods based on density functional theory. To explore the theoretical calculations for global descriptors, the standard Gaussian 09W program was used for coumarins compounds. The full geometry optimization was carried out by the B3LYP/6-311G level of theory. The octanol-water and air-water partition coefficients were also estimated using functional density theory. The order of the HOMO-LUMO energy gap for studied coumarins in the gas phase is umbelliferone (UBA) < (herniarin) HNR ~ (crenulatin) CNT < (scopoletin) SCT < (scoparone) SCO < (isoscopoletin) IST < (4-methylesculetin) MST < (umbelliferone-2- carboxylic acid) UCA < (isofraxidin) IFD < (fraxetin) FXT < (aesculetine) ACT < (dapnetine) DPT. Therefore, UBA molecule in gas phase is less stable. Compared to the measured index of electrophilicity (DE). The MST molecule is stronger, more reactive, nucleophile electrophile at the gas phase and in solvents. In all solvent phases, CNT and UCA molecules have lower values, which mean they are strong nucleophiles. From the log P values of ACT and MST coumarins are in between 1.35-1.8, so ACT and MST coumarins use oral and intestinal absorptions.

scholarly journals Structure-antioxidant Activity Relationships of Dendrocandin Analogues Determined Using Density Functional Theory

2021 ◽  
Author(s):  
Ning Zhang ◽  
Yilong Wu ◽  
Miao Qiao ◽  
Wenjuan Yuan ◽  
Xingyu Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Electron Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Hydrogen Atom Transfer ◽  
Antioxidant Compounds ◽  
Functional Theory ◽  
Chemical Structures

Abstract Quantum-chemical calculations based on the density functional theory (DFT) at the B3LYP/6–311++G(2d,2p)//B3LYP/6–31G(d,p) level were employed to study the relationship between the antioxidant properties and chemical structures of six dendrocandin (DDCD) analogues in the gas phase and two solvents (methanol and water). The hydrogen atom transfer (HAT), electron-transfer-proton-transfer (ET-PT), and sequential proton-loss-electron-transfer (SPLET) mechanisms are explored. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), reactivity indices (η, μ, ω, ω+, and ω–), and molecular electrostatic potentials (MEPs) were also evaluated. The results suggest that the D ring plays an important role in mediating the antioxidant activity of DDCDs. For all the studied compounds, indicating that HAT was identified as the most favorable mechanism, whereas the SPLET mechanism was the most thermodynamically favorable pathway in polar solvents. The results of our study should aid in the development of new or modified antioxidant compounds.

Density functional theory study of structural, magnetic and spectral properties of the CrmFen (m + n = 6) and CrmFenCu (m + n = 5) clusters

2019 ◽  
Vol 9 (6) ◽  
pp. 570-577
Author(s):  
Yunlong Chen ◽  
Zhenghua Tang ◽  
Chong He ◽  
Yong Sheng
Keyword(s):  
Density Functional Theory ◽  
Infrared Spectroscopy ◽  
Density Functional ◽  
Energy Gap ◽  
Binding Energies ◽  
Chemical Hardness ◽  
Lumo Energy ◽  
Functional Theory ◽  
Homo Lumo ◽  
Original Cluster

Using Density functional theory (DFT) to study the geometries, stability, magnetic properties and infrared spectroscopy of CrmFen (m + n = 6) and CrmFenCu (m + n = 5) clusters at the BP86/SDD level. The ground state structures of CrmFen (m + n = 6) and CrmFenCu (m + n = 5) clusters are determined according to the principles of lowest energy and no virtual frequency. On this basis, the structural and chemical stabilities are obtained by the average binding energies (Eb), chemical hardness (η) and HOMO-LUMO energy gap (Eg). The average binding energies show the substitution of a copper atom is beneficial to improve the structural stability; It can be seen Cr4Fe2 and Cr3Fe2Cu have the best chemical stability in the two cluster series from the chemical hardness and HOMO-LUMO energy gap. By calculating the magnetic moment, it is shown that Cr5Fe and CrFe4Cu have large magnetic moments, which can be understood by the spin distribution. Finally, infrared spectroscopy of the clusters are calculated, we find a copper atom substitutes the CrmFen (m + n = 6) does not change the range of vibration frequency a lot because it does not significantly change the molecular structure of the original cluster, but it changes the vibration mode of the original cluster, resulting in the strongest infrared absorption peak intensity of Cr3Fe2Cu being lower than that of Cr3Fe3.

scholarly journals A DENSITY FUNCTIONAL THEORY STUDY OF ANTIOXIDANT ACTIVITY OF ISOTHIOCYANATES IN BROCCOLI SPROUTS (BRASSICA OLERACEA L.)

2018 ◽  
Vol 54 (2C) ◽  
pp. 306 ◽  
Author(s):  
Truc Xuyen Nguyen Phan
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Brassica Oleracea ◽  
Gas Phase ◽  
Density Functional ◽  
Hydrogen Atom Transfer ◽  
Functional Theory ◽  
Vertical Ionization Energy ◽  
Vertical Electron Affinity ◽  
Brassica Oleracea L

Antioxidant activity of 9 isothiocyanate derivatives (−N=C=S) extracted from Broccolisprouts (Brassica oleracea L.) has been investigated using density functional theory (DFT) –based computational methods. Through the hydrogen atom transfer (HAT) and single electrontransfer (SET) mechanisms, three thermodynamic parameters including bond dissociationenthalpy (BDE), vertical ionization energy (IE), and vertical electron affinity (EA) werecalculated in the gas phase using B3LYP/6-311++G(3df,3p)//B3LYP/6-311G(d,p) modelchemistry. As a result, the isothiocyanate (ITC) shows potential antioxidant activity via HATmechanism. The most potential antioxidant is 3-isothiocyanato pro-1-en (3ITCP) withBDE(C−H) of 72.9 kcal/mol. The SET mechanism is not dominant in case of the studied ITCs.Moreover, the radicals formed H• removal had more reactive and less stable than the intialneutral compounds with lower IE, higher EA and ω.

scholarly journals Tuning the optoelectronic properties of hematite with rhodium doping for photoelectrochemical water splitting using density functional theory approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdur Rauf ◽  
Muhammad Adil ◽  
Shabeer Ahmad Mian ◽  
Gul Rahman ◽  
Ejaz Ahmed ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Water Splitting ◽  
Density Functional ◽  
Formation Energy ◽  
Visible Region ◽  
Photoelectrochemical Water Splitting ◽  
Theory Approach ◽  
Functional Theory

AbstractHematite (Fe2O3) is one of the best candidates for photoelectrochemical water splitting due to its abundance and suitable bandgap. However, its efficiency is mostly impeded due to the intrinsically low conductivity and poor light absorption. In this study, we targeted this intrinsic behavior to investigate the thermodynamic stability, photoconductivity and optical properties of rhodium doped hematite using density functional theory. The calculated formation energy of pristine and rhodium doped hematite was − 4.47 eV and − 5.34 eV respectively, suggesting that the doped material is thermodynamically more stable. The DFT results established that the bandgap of doped hematite narrowed down to the lower edge (1.61 eV) in the visible region which enhanced the optical absorption and photoconductivity of the material. Moreover, doped hematite has the ability to absorb a broad spectrum (250–800) nm. The enhanced optical absorption boosted the photocurrent and incident photon to current efficiency. The calculated results also showed that the incorporation of rhodium in hematite induced a redshift in optical properties.

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