scholarly journals IR spectral manifestation of tin impurity sites in titanium dioxide

2021 ◽  
Vol 12 (3) ◽  
pp. 184-189
Author(s):  
O. V. Smirnova ◽  
◽  
A. G. Grebenyuk ◽  
V. V. Lobanov ◽  
T. A. Khalyavka ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Absorption Spectrum ◽  
Ir Spectra ◽  
Band Gap ◽  
Density Functional ◽  
Spectral Characteristics ◽  
Basis Set ◽  
Ultraviolet Region ◽  
Vis Spectroscopy ◽  
Ft Ir

It is known that titanium dioxide as photocatalyst has significant drawback - limited absorption spectrum in the ultraviolet region makes it impossible to use solar energy. To expands the absorption spectrum of TiO2, the doping of impurities (metal, non-metal, etc.) were used. They affected the electronic structure and spectral characteristics of TiO2. The aim of our work was to investigate the influence of tin impurities on spectral characteristics of titanium dioxide using experimental and theoretical methods. The TiO2 powders modified by different amount of tin (Sn/TiO2) were synthesized by sol-gel method. The samples were characterized by SEM, EDX, FT-IR and UV-VIS spectroscopy. It has been found that Sn/TiO2 consists of fragmented agglomerates in the range of 5–10 mm. EDX spectroscopy prove that powders include Ti, O and Sn elements. Modification of titanium dioxide with tin leads to band gap narrowing of samples, which explains by insertion of Sn atoms into crystal lattice of titanium dioxide, because Ti4+ and Sn4+ ions radii are close. The band gap values increased with increasing of tin content. The work also analyzes the vibrational spectra of Sn/TiO2 both experimentally and theoretically. In order to interpret the results obtained, quantum chemical calculations on the spatial and electronic structures of cluster models of titanium dioxide (anatase) with inserted tin atoms using the density functional theory B3LYP method and the basis set 6-31G (d, p) were carried out and the corresponding FT-IR spectra have been simulated. By comparing the experimental and theoretical results, the influence has been analyzed of the number and arrangement of impurity tin atoms in clusters on the observed IR spectra of the samples. This makes it possible to forgive the most probable structural motives of titanium dioxide particles doped with tin atoms, as well as to establish the fact of the presence of tin atoms in the samples. Based on the comparison of the IR spectra of samples with different numbers of tin atoms, it is possible to quantify their composition.

scholarly journals A quantum chemical study on the effect of titanium dioxide modification with non-metals on its spectral characteristics

2020 ◽  
Vol 11 (4) ◽  
pp. 539-546
Author(s):  
O. V. Smirnova ◽  
◽  
A. G. Grebenyuk ◽  
V. V. Lobanov ◽  
◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Quantum Chemical ◽  
Density Functional ◽  
Spectral Characteristics ◽  
Quantum Chemical Study ◽  
Visible Region ◽  
Wavelength Region ◽  
Basis Set ◽  
Oxidation States ◽  
Impurity Atoms

The experimental results obtained in the study on the possibility of sensitizing titanium dioxide (polymorphic anatase phase) to the visible region of the spectrum by doping and co-doping with impurities of non-metals in order to create effective photocatalysts for the decomposition of organic compounds have been analyzed. The presence of impurity atoms appears to result in a change in the electronic structure of the titanium dioxide matrix, in the appearance of “impurity bands” and in the narrowing of the energy gap of titanium dioxide. Such a modification is accompanied by an extension of the spectral range of sensitivity of photoactive solids to the long-wavelength region of the spectrum and, therefore, can be used to improve the catalytic properties of these materials. Spectral manifestations of carbon impurities in titanium dioxide in the form of carbide and carbonate, as well as sulfur in the forms of sulfite, sulfide, and sulfate, have been studied by the density functional theory method. A Ti14H22O39 cluster model was chosen for the titanium dioxide matrix. The calculations were carried out in the framework of the cluster approximation, using functional B3LYP and basis set 6-31G (d, p). Comparison of the results of quantum chemical calculations with the available experimental data shows that the impurity sulfur and carbon atoms in titanium dioxide, which are in different coordination states and different oxidation states, appear in different spectral ranges. This circumstance makes it possible to elucidate the structure of the samples based on the experimental spectra. A change in the coordination and oxidation states of impurity atoms leads to spectral shifts and splitting of peaks, which can reach 1.5 eV (XPS). The presence of admixtures of non-metals leads to a change in color (deepening in the case of sulfide or carbide) of the samples, appearing in the corresponding UV spectra.

Density functional theory, Comparative vibrational spectroscopic studies, HOMO-LUMO, and NBO analysis of Trichloro isocyanuric acid and Trithio cyanuric acid

2015 ◽  
Vol 8 (3) ◽  
pp. 2197-2221
Author(s):  
Theraviyum Chithambarathanu ◽  
M. Darathi ◽  
J. DaisyMagdaline ◽  
S. Gunasekaran
Keyword(s):  
Density Functional ◽  
Cyanuric Acid ◽  
Nbo Analysis ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Point Energy ◽  
Isocyanuric Acid ◽  
Ft Ir ◽  
Homo Lumo ◽  
Ft Raman

The molecular vibrations of Trichloro isocyanuric acid (C3Cl3N3O3) and Trithio cyanuric acid (C3H3N3S3) have been investigated in polycrystalline sample at room temperature by Fourier Transform Infrared (FT-IR) and FT-Raman spectroscopies in the region 4000-450 cm-1 and 4000-50 cm-1 respectively, which provide a wealth of structural information about the molecules. The spectra are interpreted with the aid of normal co-ordinate analysis following full structure optimization and force field calculations based on density functional theory   (DFT) using standard B3LYP / 6-311++ G (d, p) basis set for investigating the structural and spectroscopic properties. The vibrational frequencies are calculated and the scaled values are compared with experimental FT-IR and FT-Raman spectra. The scaled theoretical wave numbers shows very good agreement with experimental ones. The complete vibrational assignments are performed on the basis of potential energy distribution (PED) of vibrational modes, calculated with scaled quantum (SQM) method. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that change in electron density (ED) in σ* and π* anti-bonding orbitals and second order delocalization   energy (E2) confirm the occurrence of Intra molecular Charge Transfer (ICT) within the molecule. The thermodynamic properties like heat capacity, entropy, enthalpy and zero point energy have been calculated for the molecule. The frontier molecular orbitals have been visualized and the HOMO-LUMO energy gap has been calculated. The Molecular Electrostatic Potential (MEP) analysis reveals the sites for electrophilic attack and nucleophilic reactions in the molecule.

scholarly journals Synthesis of Fluorene Based Alternating Copolymers using Direct Arylation Polymerization

2021 ◽  
Vol 33 (2) ◽  
pp. 393-398
Author(s):  
Mohd Sani Sarjadi ◽  
Yap Leong Khen ◽  
Xin Lin Wong ◽  
Zuhair Jamain ◽  
Md Lutfor Rahman
Keyword(s):  
Solar Cell ◽  
Band Gap ◽  
Active Layer ◽  
Optical Band Gap ◽  
Direct Arylation ◽  
Low Band Gap ◽  
Alternating Copolymers ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Direct Arylation Polymerization

Many researches have been done to obtain a low band gap and high Polymeric solar cell (PSCs) polymer either by creating new polymer or revising reported polymers from previous studies. In present work, two new copolymers were synthesized through direct arylation polymerization to produce poly(9,9-didodecylfluorene-alt-benzo[c][1,2,5]thiadiazole (P1) and poly(9,9-didodecylfluorene-altthieno[ 3,2-b]thiophene) (P2). The P1 and P2 are donor-accepter copolymers. P1 and P2 were compared to investigate its suitability to be applied in PSCs. The polymers obtained were characterized using FT-IR, NMR and UV-Vis spectroscopy. P1 shows two adsorption bands at λmax1 = 243 nm and λmax2 = 320 nm, whereas P2 also shows two adsorption bands at λmax1 = 243 nm and λmax2 = 427 nm. The optical band gap was calculated, P1 enabled band gap of 3.88 eV while P2 showed band gap of 2.91 eV. This work could be provided an insight to design and synthesize more efficient fluorene-based copolymers as active layer of PSCs in due course.

Structural, electronic, and mechanical properties of anatase titanium dioxide

2019 ◽  
Vol 15 (2) ◽  
pp. 306-316 ◽  
Author(s):  
Debashish Dash ◽  
Chandan Kumar Pandey ◽  
Saurabh Chaudhary ◽  
Susanta Kumar Tripathy
Keyword(s):  
Mechanical Properties ◽  
Titanium Dioxide ◽  
Electronic Properties ◽  
Density Functional ◽  
Paper Industry ◽  
Ground Level ◽  
Basis Set ◽  
Indirect Transition ◽  
Content Type ◽  
Valence Region

PurposeThe purpose of this paper is to analyze various properties of anatase titanium dioxide (TiO2) nanoparticles. Further, it proposes to implement Linear Combinations of Atomic Orbitals (LCAO) basis set under the framework of density functional theory and outline how LCAO is able to provide improved results in terms of various mechanical properties rather than plane wave and other theoretical results.Design/methodology/approachThis paper provides an exploratory study on anatase TiO2by implementing OLCAO–DFT–LDA–LBFGS–EOS–PZ algorithms to find out various ground-level properties. The data so obtained are complemented by various analysis using mathematical expressions, description of internal processes occurred and comparison to others’ analytical results.FindingsThe paper provides some empirical insights on how mechanical properties of anatase TiO2improved by implementing LCAO methodology. From the analysis of electronic properties, it is seen that the anatase TiO2supports the inter band indirect transition from O-2p in valence region to Ti-3d in the conduction region.Research limitations/implicationsMost of the electronic properties are underestimated because a single exchange-correlation potential is not continuous across the gap. This gap can be enhanced by implementing Green’s function in place of DFT and the other way is to implement self-interaction correction.Practical implicationsThe use of anatase TiO2is primarily used for catalytic applications. This is also used to enhance the quality of paper in the paper industry. Additionally, this is used as a prime ingredient in cosmetic industry.Originality/valueThis paper fulfills an identified need to study how LCAO, another basis set, plays an important role in improving material properties.

Experimental and Theoretical Studies on the Molecular Structure, FT-IR, NMR, HOMO, LUMO, MESP, and Reactivity Descriptors of (E)-1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one

2020 ◽  
Vol 17 (SpecialIssue1) ◽  
pp. 54-72
Author(s):  
Rahul Ashok Shinde ◽  
Vishnu A shok Adole ◽  
Bapu Sonu Jagdale ◽  
Thansing Bhavsing Pawar
Keyword(s):  
Molecular Structure ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Dft Method ◽  
Basis Set ◽  
Group Symmetry ◽  
Ir Absorption ◽  
Hydrogen Atoms ◽  
Reactivity Descriptors ◽  
Ft Ir

The present research deals with the synthesis, characterization and density functional theory (DFT) study of (E)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (DTMPP). For the computational investigation, DFT method at B3LYP/6-311++G(d,p) basis set has been used. Herein, structural properties like molecular structure, bond lengths, and bond angles of the DTMPP have been explored. The all-important examination of the electronic properties; HOMO and LUMO energies were studied by the time-dependent DFT (TD-DFT) method. The experimental and theoretical spectroscopic Investigation on FT-IR, 1HNMR, 13C NMR has been unveiled in the present research. To study the chemical behaviour of the DTMPP, Mulliken atomic charges, molecular electrostatic surface potential, and reactivity descriptors have been explored. The dipole moment of the DTMPP is 1.27 Debye with C1 point group symmetry and -1225.77 a.u. E(B3LYP) energy. The most electropositive carbon and hydrogen atoms in the DTMPP are C14 and H27 respectively. The C1-C6 bond is the longest (1.4089 Å) C=C bond in the DTMPP. The oxygen atom O33 is having short contact interaction with the hydrogen atom H44 with a distance of 3.3258 Å. The molecular electrostatic potential plot predicts the positive electrostatic potential is around hydrogen atoms. The FT-IR assignments were made by comparing the experimental FT-IR absorption peaks with the scaled frequencies obtained using DFT method. Furthermore, some valuable insights on thermochemical data are obtained using the harmonic frequencies at same basis set.

Vibrational spectroscopic and conformational studies of 1-(4-pyridyl)piperazine

2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Özgür Alver ◽  
Mustafa Şenyel
Keyword(s):  
Density Functional ◽  
Structural Parameters ◽  
Density Functional Theory Method ◽  
Basis Set ◽  
Stable Form ◽  
Functional Theory ◽  
B3lyp Method ◽  
Ft Ir ◽  
Hybrid Density Functional ◽  
Ir And Raman

AbstractPossible stable conformers of the 1-(4-pyridyl)piperazine (1-4pypp) molecule were experimentally and theoretically studied by FT-IR and Raman spectroscopy. FT-IR and Raman spectra were recorded in the region of 4000–200 cm−1. Optimized geometric structures related to the minimum on the potential energy surface were investigated by the B3LYP hybrid density functional theory method using the 6-31G(d) basis set. Comparison of the experimental and theoretical results indicates that the density functional B3LYP method provides satisfactory results for the prediction of vibrational wavenumbers and structural parameters and equatorial-equatorial (e-e) isomer is supposed to be the most stable form of the 1–4pypp molecule.

scholarly journals Density functional theory study on the molecular structure of loganin

2011 ◽  
Vol 25 (6) ◽  
pp. 287-302 ◽  
Author(s):  
Anoop Kumar Pandey ◽  
Shamoon Ahmad Siddiqui ◽  
Apoorva Dwivedi ◽  
Kanwal Raj ◽  
Neeraj Misra
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Solid Phase ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
B3lyp Method ◽  
Ft Ir ◽  
Detailed Interpretation

The computational Quantum Chemistry (QC) has been used for different types of problems, for example: structural biology, surface phenomena and liquid phase. In this paper we have employed the density functional method for the study of molecular structure of loganin. The equilibrium geometry, harmonic vibrational frequencies and infrared intensities were calculated by B3LYP/6-311G (d, p) method and basis set combinations. It was found that the optimized parameters obtained by the DFT/B3LYP method are very near to the experimental ones. A detailed conformational analysis was carried out. A detailed interpretation of the infrared spectra of loganin is also reported in the present work. The FT-IR spectra of loganin were recorded in solid phase. The thermodynamic calculations related to the title compound were also performed at B3LYP/6-311G (d, p) level of theory.

Resonance Raman and absorption infrared with density functional theory studies of Fe(III)/Fe(II) and Ni(II) complexes of modified 21-oxaporphyrins

2013 ◽  
Vol 17 (04) ◽  
pp. 289-308 ◽  
Author(s):  
Mateusz Fościak ◽  
Edyta Proniewicz ◽  
Krzysztof Zborowski ◽  
Younkyoo Kim ◽  
Leonard M. Proniewicz
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Resonance Raman ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ft Ir ◽  
Optimized Geometries ◽  
Good Agreement

This work presents a complete vibrational analysis of iron [ Fe (II) and Fe (III)] and nickel [ Ni (II)] complexes with 5,10,15,20-tetraphenyl-21-oxaporphyrin [OTPPH] and 5,20-bis(p-tolyl)-10,15-diphenyl-21-oxaporphyrin [ODTDPPH]. In these porphyrins, a furan ring replaces one of the pyrrole rings. The six-coordinate (OTPP) FeIIICl2 and (ODTDPP) FeIIICl2 as well as the five-coordinate (OTPP) FeIICl and (OTPP) NiIICl complexes were investigated using experimental and theoretical methods. The experimental part of this work involved Fourier-transform absorption infrared (FT-IR), resonance Raman (RR), and electron absorption (UV-vis) measurements for all of the investigated complexes. In the theoretical section, optimized geometries and vibrational frequencies for model compounds are provided. The theoretical calculations were performed at the B3LYP level with the LANL2DZ basis set. Good agreement was achieved between the experimental and theoretical vibrational spectra. In addition, charge distributions (GAPT) and geometrical aromaticity indices (Bird's I5 and HOMA) were calculated and discussed.

scholarly journals DFT and TD-DFT Study of Structure and Properties of Semiconductive Hybrid Networks Formed by Bismuth Halides and Different Polycyclic Aromatic Ligands

2011 ◽  
Vol 8 (s1) ◽  
pp. S195-S202
Author(s):  
Y. Belhocine ◽  
M. Bencharif
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Density Functional ◽  
Relativistic Effects ◽  
Spectroscopic Properties ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Td Dft ◽  
Polycyclic Aromatic

The structure and spectroscopic properties of polycyclic aromatic ligands of 2,3,6,7,10,11-hexakis (alkylthio) triphenylene (alkyl: methyl, ethyl, and isopropyl; corresponding to the abbreviations of the molecules: HMTT, HETT and HiPTT) were studied using density functional theory (DFT) and time dependent density functional theory (TD-DFT) methods with triple-zeta valence polarization (TZVP) basis set. It was shown that the type of functional theory used, Becke-Perdew (BP) and Leeuwen-Baerends (LB94) implemented in Amsterdam Density functional (ADF) program package, does not have essential influence on the geometry of studied compounds in both ground and excited states. However, significant differences were obtained for the band gap values with relativistic effects of the zero order regular approximation scalar corrections (ZORA) and LB94 functional seems to reproduce better the experimental optical band gap of these systems.

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