1
|
Density functional theoretical study, spectroscopic characterization and molecular docking of the diuretic drug, spironolactone, adsorbed on AuNPs surface and in-vitro studies based on anticancer activity studies against A549 lung cancer cell line. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
2
|
Philip BM, John JS, V S, Kuruvilla TK, Paulose TAP, Sajan D. Vibrational spectra and molecular docking studies of bergapten isolated from Melicopedenhamii leaves as anti-breast cancer agents. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.132656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
3
|
Spectroscopic characterization and structural insights of 4-[(1E)-3-(4-methoxyphenyl)-3-oxoprop-1-en-1-yl] phenyl 4-methylbenzene-1-sulfonate using vibrational, electronic spectra and quantum chemical calculations. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129144] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
4
|
Ishiguro Y, Yamakita Y, Hayashi N. Penning ionization electron spectroscopy of anisole, thioanisole, and selenoanisole by collision with He*(23S): Conjugation effects and conformational stability. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137653] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
5
|
Barclay MS, Elles CG, Caricato M. On the Discrepancy between Experimental and Calculated Raman Intensities for Conjugated Phenyl and Thiophene Derivatives. J Phys Chem A 2020; 124:4678-4689. [PMID: 32392419 DOI: 10.1021/acs.jpca.0c00363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Compared with experimental spectra, calculations for conjugated phenyl and thiophene oligomers tend to overestimate the ground state Raman intensities of higher-frequency vibrations (1200-1800 cm-1) relative to the intensities at lower frequencies (<1200 cm-1). The discrepancy was observed in previous benchmarking work that examined the method dependence of the calculated Raman spectra for a series of aromatic molecules. This paper further investigates the nature of the discrepancy by examining the role of anharmonic corrections and the dependence of the calculated Raman spectra on the inter-ring torsion angle for the representative molecules biphenyl (BP), 2-phenylthiophene (PT), and 2,2'-bithiophene (BT). Perturbative anharmonic corrections to the spectra calculated using density functional theory (DFT) provide only slightly better agreement with experiment. On the other hand, calculations at larger torsion angles give up to 30% improvement in the relative Raman intensities compared with the spectra calculated at the optimized geometries. The torsion-angle dependence of the Raman intensities is most pronounced for delocalized C-C and C-S stretching modes, and less pronounced for bending and ring distortion modes that do not involve inter-ring stretching. Higher-level calculations using the coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] method indicate that DFT underestimates the energy barrier for torsion isomerization at small angles, and it overestimates the barriers at large angles, thus predicting minimum geometries at torsion angles that are too small. Therefore, the results suggest that the discrepancy in relative Raman intensities may be related to an overestimation of inter-ring conjugation by DFT, which also tends to favor geometries that are too planar.
Collapse
Affiliation(s)
- Matthew S Barclay
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| |
Collapse
|
6
|
Barclay MS, Elles CG, Caricato M. Benchmark Study of Ground-State Raman Spectra in Conjugated Molecules. J Chem Theory Comput 2019; 16:612-620. [DOI: 10.1021/acs.jctc.9b00960] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew S. Barclay
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G. Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| |
Collapse
|
7
|
Praveen PA, Babu RR. Evaluation of nonlinear optical properties from molecular descriptors of benzimidazole metal complexes by principal component analysis. J Mol Graph Model 2019; 93:107447. [PMID: 31521880 DOI: 10.1016/j.jmgm.2019.107447] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/30/2019] [Accepted: 08/30/2019] [Indexed: 11/19/2022]
Abstract
In the present work, semiempirical quantum chemical method (PM6) has been used for the simulation of molecular descriptors of first row transition metal ions incorporated benzimidazole metal complexes. Metal complexes with and without substituents are considered for the analysis. In both the cases, molecules show distinct properties with respect to the molecular descriptors. Since the dimension of the data set is large, principal component analysis has been used and the obtained principal components, PCA1 and PCA2, are linearly regressed with hyperpolarizability values. The obtained results indicate that molecular energy plays a dominant role in the nonlinear optical properties of benzimidazole metal complexes. Further, it is observed that the bond angle, global hardness and heat of formation of the molecules have considerable impact on the hyperpolarizability values.
Collapse
Affiliation(s)
- P A Praveen
- Department of Physics, Indian Institute of Science Education and Research, Tirupati, 517 507, Andhra Pradesh, India; Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli, 620 024, Tamilnadu, India
| | - R Ramesh Babu
- Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli, 620 024, Tamilnadu, India.
| |
Collapse
|
8
|
Density functional theoretical analysis with experimental, invitro bioactivity and molecular docking investigations on the pesticide Albendazole. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.01.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
9
|
Almutairi MS, Xavier S, Sathish M, Ghabbour HA, Sebastian S, Periandy S, Al-Wabli RI, Attia MI. Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) profiling and computational studies on methyl 5-methoxy-1H-indole-2-carboxylate: A potential precursor to biologically active molecules. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2016.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
10
|
Manzoor Ali M, George G, Ramalingam S, Periandy S, Gokulakrishnan V. Vibrational [FT-IR, FT-Raman] analysis, NMR and mass – Spectroscopic investigation on 3,6-Dimethylphenanthrene using computational calculation. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.05.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
11
|
Alen S, Sajan D, Joseph L, Chaitanya K, Shettigar V, Jothy VB. Synthesis, growth, vibrational spectral investigations and structure–property relationship of an organic NLO crystal: 3,4-Dimethoxy chalcone. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.07.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
12
|
Balamurugan N, Charanya C, SampathKrishnan S, Muthu S. Molecular structure, vibrational spectra, first order hyper polarizability, NBO and HOMO-LUMO analysis of 2-amino-5-bromo-benzoic acid methyl ester. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 137:1374-1386. [PMID: 25306133 DOI: 10.1016/j.saa.2014.09.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/29/2014] [Accepted: 09/18/2014] [Indexed: 06/04/2023]
Abstract
An organic crystal of 2-amino-5-bromobenzoic acid methyl ester [abbreviated at 2A5BrBAMe], single crystal, belongs to the amino acid group, were grown by the slow evaporation solution growth technique at room temperature. The grown crystal had been subjected to single-crystal X-ray diffraction technique and cell parameters of the crystal were determined. The quantitative analysis on the crystal had been carried out using Fourier transform infrared (FTIR) and Fourier transform Raman (FT-Raman) spectral measurements. The molecular structures, vibrational wave numbers were calculated using DFT (B3LYP) method with 6-311++G(d,p) basis set. The formation of the hydrogen bond was investigated using NBO calculations. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (μ) and polarizability (α0), anisotropy polarizability (Δα) and first order hyperpolarizability (β0) of the molecule have been reported.
Collapse
Affiliation(s)
- N Balamurugan
- Department of Physics, Sri Venkateshwara College of Engineering, Sriperumbudur 602105, Tamil Nadu, India; Department of Physics, PERI Institute of Technology, Chennai, Tamil Nadu, India
| | - C Charanya
- Department of Physics, Sri Venkateshwara College of Engineering, Sriperumbudur 602105, Tamil Nadu, India
| | - S SampathKrishnan
- Department of Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602105, Tamil Nadu, India
| | - S Muthu
- Department of Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602105, Tamil Nadu, India.
| |
Collapse
|
13
|
Balachandran V, Santhi G, Karpagam V, Revathi B, Karabacak M. Spectroscopic investigation, natural bond orbital analysis, HOMO-LUMO and thermodynamic functions of 2-tert-butyl-5-methyl anisole using DFT (B3LYP) calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 136 Pt B:451-463. [PMID: 25448946 DOI: 10.1016/j.saa.2014.09.057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 08/23/2014] [Accepted: 09/18/2014] [Indexed: 06/04/2023]
Abstract
The optimized molecular structure and corresponding vibrational assignments of 2-tert-butyl-5-methyl anisole (TBMA) have been investigated using density functional theory (DFT)/B3LYP with 6-31G(d,p) and 6-311++G(d,p) basis sets investigation of the relative orientation of the methoxy group has shown two conformers (O-cis) and (O-trans) exist. The vibrational analysis of the stable conformer of the title compound is performed by means of infrared absorption and Raman spectroscopy in combination with theoretical simultaneously. The natural bond orbital (NBO) analysis is useful to understand the intra-molecular hyper conjugative interaction lone pair and π(∗)(C-C), σ(∗)(C-H) bond orbital. HOMO and LUMO energies show that charge transfer occurs in the molecule, therefore; HOMO, LUMO and molecular electrostatic potential (MEP) were calculated and analyzed. (1)H and (13)C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data. The thermodynamic functions of TBMA were calculated by B3LYP/6-311+G(d,p) basis set.
Collapse
Affiliation(s)
- V Balachandran
- Centre for Research, Department of Physics, AA Government Arts College, Musiri, Tiruchirappalli 621211, India.
| | - G Santhi
- Department of Physics, Government Arts College, Karur 639005, India
| | - V Karpagam
- Department of Physics, Srinivasan Polytechnic College, Perambalur 621212, India
| | - B Revathi
- Centre for Research, Department of Physics, AA Government Arts College, Musiri, Tiruchirappalli 621211, India
| | - M Karabacak
- Department of Mechatronics Engineering, H.F.T. Technology Faculty, Celal Bayar University, 45400 Turgutlu, Manisa, Turkey
| |
Collapse
|
14
|
Balachandran V, Karpagam V, Revathi B, Kavimani M, Santhi G. Conformational stability, vibrational and NMR analysis, chemical potential and thermodynamical parameter of 3-tert-butyl-4-hydroxyanisole. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 135:1039-1051. [PMID: 25173520 DOI: 10.1016/j.saa.2014.07.093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Revised: 07/12/2014] [Accepted: 07/29/2014] [Indexed: 06/03/2023]
Abstract
The FT-IR and FT-Raman spectra of 3-tert-butyl-4-hydroxyanisole (TBHA) molecule have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. Optimized geometrical structure, harmonic vibrational frequencies has been computed by B3LYP level using 6-31G (d,p) and 6-311+G (d,p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The Mulliken charges, the natural bonding orbital (NBO) analysis, the first-order hyperpolarizability of the investigated molecule were computed using DFT calculations. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and analyzed. The isotropic chemical shift computed by (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the TBHA calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations.
Collapse
Affiliation(s)
- V Balachandran
- Research Department of Physics, AA Government Arts College, Musiri 621211, India.
| | - V Karpagam
- Department of Physics, Sri Saradha College for Women, Perambalur 621212, India
| | - B Revathi
- Research Department of Physics, AA Government Arts College, Musiri 621211, India
| | - M Kavimani
- Research Department of Physics, AA Government Arts College, Musiri 621211, India
| | - G Santhi
- PG Department of Physics, Government Arts College, Karur 639005, India
| |
Collapse
|
15
|
Kandasamy M, Velraj G, Kalaichelvan S, Mariappan G. Characterization of 1,5-dimethoxynaphthalene by vibrational spectroscopy (FT-IR and FT-Raman) and density functional theory calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 134:191-199. [PMID: 25014641 DOI: 10.1016/j.saa.2014.06.092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 06/03/2023]
Abstract
In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and natural bond orbital (NBO) analysis of 1,5-dimethoxynaphthalene. The optimized molecular structure, atomic charges, vibrational frequencies and natural bond orbital analysis of 1,5-dimethoxynaphthalene have been studied by performing DFT/B3LYP/6-31G(d,p) level of theory. The FTIR, FT-Raman spectra were recorded in the region of 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of the most fundamentals is very small. The formation of hydrogen bond was investigated in terms of the charge density by the NBO analysis. Natural Population Analysis (NPA) was used for charge determination in the title molecule. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.
Collapse
Affiliation(s)
- M Kandasamy
- Department of Physics, Arignar Anna Govt. Arts College, Namakkal 637 002, India.
| | - G Velraj
- Department of Physics, Periyar University, Salem 636 011, India
| | - S Kalaichelvan
- Tamilnadu Teachers Education University, Lady Willington College Campus, Chennai 600 005, India
| | - G Mariappan
- Department of Physics (Engg.), Annamalai University, Annamalai Nagar 608 002, Chidambaram, Tamil Nadu, India
| |
Collapse
|
16
|
Govindarasu K, Kavitha E. Vibrational spectra, molecular structure, NBO, UV, NMR, first order hyperpolarizability, analysis of 4-Methoxy-4'-Nitrobiphenyl by density functional theory. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 122:130-141. [PMID: 24299985 DOI: 10.1016/j.saa.2013.10.122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 10/16/2013] [Accepted: 10/31/2013] [Indexed: 06/02/2023]
Abstract
In this study, geometrical optimization, spectroscopic analysis, electronic structure and nuclear magnetic resonance studies of 4-Methoxy-4'-Nitrobiphenyl (abbreviated as 4M4'NBPL) were investigated by utilizing HF and DFT/B3LYP with 6-31G(d,p) as basis set. The equilibrium geometry, vibrational wavenumbers and the first order hyperpolarizability of the 4M4'NBPL have been calculated with the help of density functional theory computations. The FT-IR and FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. Natural Bond Orbital (NBO) analysis is also used to explain the molecular stability. The UV-Vis absorption spectra of the title compound dissolved in chloroform were recorded in the range of 200-800 cm(-1). The HOMO-LUMO energy gap explains the charge interaction taking place within the molecule. Good correlation between the experimental (1)H and (13)C NMR chemical shifts in chloroform solution and calculated GIAO shielding tensors were found. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizability of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. The chemical reactivity and thermodynamic properties of 4M4'NBPL at different temperature are calculated. In addition, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.
Collapse
Affiliation(s)
- K Govindarasu
- Department of Physics (Engg.), Annamalai University, Annamalainagar 608 002, India
| | - E Kavitha
- Department of Physics (Engg.), Annamalai University, Annamalainagar 608 002, India.
| |
Collapse
|
17
|
Joseph L, Sajan D, Chaitanya K, Isac J. Molecular conformational analysis, vibrational spectra and normal coordinate analysis of trans-1,2-bis(3,5-dimethoxy phenyl)-ethene based on density functional theory calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 122:375-386. [PMID: 24317264 DOI: 10.1016/j.saa.2013.11.077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 11/08/2013] [Accepted: 11/13/2013] [Indexed: 06/02/2023]
Abstract
The conformational behavior and structural stability of trans-1,2-bis(3,5-dimethoxy phenyl)-ethene (TDBE) were investigated by using density functional theory (DFT) method with the B3LYP/6-311++G(d,p) basis set combination. The vibrational wavenumbers of TDBE were computed at DFT level and complete vibrational assignments were made on the basis of normal coordinate analysis calculations (NCA). The DFT force field transformed to natural internal coordinates was corrected by a well-established set of scale factors that were found to be transferable to the title compound. The infrared and Raman spectra were also predicted from the calculated intensities. The observed Fourier transform infrared (FTIR) and Fourier transform (FT) Raman vibrational wavenumbers were analyzed and compared with the theoretically predicted vibrational spectra. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP).
Collapse
Affiliation(s)
- Lynnette Joseph
- Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala, India; Department of Physics, CMS College, Kottayam 686001, Kerala, India
| | - D Sajan
- Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala, India.
| | - K Chaitanya
- Department of Chemistry, Nanjing University of Science and Technology, Xialingwei 200, Nanjing, People's Republic of China
| | - Jayakumary Isac
- Department of Physics, CMS College, Kottayam 686001, Kerala, India
| |
Collapse
|
18
|
Sert Y, El-Emam AA, Al-Deeb OA, Al-Turkistani AA, Ucun F, Cırak C. The biomolecule, 2-[(2-methoxyl)sulfanyl]-4-(2-methylpropyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile: FT-IR, Laser-Raman spectra and DFT. SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 126:86-97. [PMID: 24589995 DOI: 10.1016/j.saa.2014.01.140] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/21/2014] [Accepted: 01/27/2014] [Indexed: 11/25/2022]
Abstract
In this study, the experimental and theoretical vibrational frequencies of a newly synthesized potential chemotherapeutic agent namely, 2-[(2-methoxyl)sulfanyl]-4-(2-methylpropyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile have been investigated. The experimental FT-IR (4000-400cm(-1)) and Laser-Raman spectra (4000-100cm(-1)) of the molecule in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis by using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with the results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.
Collapse
Affiliation(s)
- Yusuf Sert
- Department of Physics, Faculty of Art & Sciences, Bozok University, Yozgat 66100, Turkey.
| | - Ali A El-Emam
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Omar A Al-Deeb
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | | | - Fatih Ucun
- Department of Physics, Faculty of Art & Sciences, Süleyman Demirel University, Isparta 32100, Turkey
| | - Cağrı Cırak
- Department of Physics, Faculty of Art & Sciences, Erzincan University, Erzincan 24100, Turkey
| |
Collapse
|
19
|
Cinar Z, Karabacak M, Cinar M, Kurt M, Chinna Babu P, Sundaraganesan N. The infrared, Raman, NMR and UV spectra, ab initio calculations and spectral assignments of 2-amino-4-chloro-6-methoxypyrimidine. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 116:451-459. [PMID: 23973593 DOI: 10.1016/j.saa.2013.07.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 07/04/2013] [Accepted: 07/21/2013] [Indexed: 06/02/2023]
Abstract
The 2-amino-4-chloro-6-methoxypyrimidine abbreviated as ACMP have been investigated by both the experimental and theoretical methods; through this work we provide the essential fact about the structural and vibrational insights. The optimized molecular structure, atomic charges, vibrational frequencies and ultraviolet spectral interpretation of ACMP have been studied by performing DFT/B3LYP/6-311++G(df,pd) level of theory. The FT-IR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1) respectively. The UV absorption spectrum of the compound that dissolved in ethanol and water solution were recorded in the range of 200-400 nm. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Based on the UV spectrum and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. The (1)H, (13)C and DEPT 135 nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated using with the Gauge Including Atomic Orbital (GIAO) method and compared with experimental results. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.
Collapse
Affiliation(s)
- Z Cinar
- Department of Physics, Afyon Kocatepe University, 03040 Afyonkarahisar, Turkey
| | | | | | | | | | | |
Collapse
|
20
|
Joshi BD, Srivastava A, Gupta V, Tandon P, Jain S. Spectroscopic and quantum chemical study of an alkaloid aristolochic acid I. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 116:258-269. [PMID: 23954541 DOI: 10.1016/j.saa.2013.07.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 07/10/2013] [Accepted: 07/21/2013] [Indexed: 06/02/2023]
Abstract
Aristolochic acids (AAs) (Aristolochiaceae) are used in the traditional Chinese herb medicine. We have presented the geometry optimization, electrostatic potential surface, frontier orbital energy gap and vibrational wavenumbers of aristolochic acid I (AA I) using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method employing 6-311G(d,p) basis set. A complete vibrational assignment has been done on the basis of calculations on monomer and dimer of AA I. The UV-vis absorption spectrum has been recorded in ethanol solvent and compared with the calculated one in the gas phase as well as in solvent environment (integral-equation formalism polarizable continuum model; IEF-PCM) using TD-DFT/6-31G basis set. A short outline of the NBO analysis segment with their structural meaning has been presented. The variation of thermodynamic properties with temperature was calculated theoretically and the thermal response of the compound has been recorded with the help of differential scanning calorimetry (DSC) in N2 environment.
Collapse
Affiliation(s)
- Bhawani Datt Joshi
- Department of Physics, University of Lucknow, Lucknow 226007, India; Department of Physics, Siddhanath Sc. Campus, Tribhuvan University, Nepal
| | | | | | | | | |
Collapse
|
21
|
Arivazhagan M, Anitha Rexalin D, Geethapriya J. Vibrational spectra, DFT quantum chemical calculations and conformational analysis of P-iodoanisole. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 113:236-249. [PMID: 23727676 DOI: 10.1016/j.saa.2013.04.106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/15/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
The solid phase FT-IR and FT-Raman spectra of P-iodoanisole (P-IA) have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by ab initio (HF) and density functional theory (B3LYP) methods with LanL2DZ as basis set. The potential energy surface scan for the selected dihedral angle of P-IA has been performed to identify stable conformer. The optimized structure parameters and vibrational wavenumbers of stable conformer have been predicted by density functional B3LYP method with LanL2DZ (with effective core potential representations of electrons near the nuclei for post-third row atoms) basis set. The nucleophilic and electrophilic sites obtained from the molecular electrostatic potential (MEP) surface were calculated. The temperature dependence of thermodynamic properties has been analyzed. Several thermodynamic parameters have been calculated using B3LYP with LanL2DZ basis set.
Collapse
Affiliation(s)
- M Arivazhagan
- PG & Research Department of Physics, A.A. Government Arts College, Musiri 621 211, Tamil Nadu, India.
| | | | | |
Collapse
|
22
|
Sheela NR, Sampathkrishnan S, Thirumalai Kumar M, Muthu S. Quantum mechanical study of the structure and spectroscopic, first order hyperpolarizability, Fukui function, NBO, normal coordinate analysis of phenyl-N-(4-methyl phenyl) nitrone. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 112:62-77. [PMID: 23659952 DOI: 10.1016/j.saa.2013.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/20/2013] [Accepted: 04/01/2013] [Indexed: 06/02/2023]
Abstract
The title compound, Phenyl-N-(4-Methyl Phenyl) Nitrone (PN4MPN) was synthesized and characterized by FT-IR, FT-Raman and (1)HNMR, (13)CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at the Hartree-Fock/6-311++G(d,p) and three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The calculated results show that the predicted geometry can well reproduce the structural parameters. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. The dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the investigated molecule is calculated by using HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) methods on the finite field approach. Besides, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and thermodynamical properties are described from the computational process. The electron density-based local reactivity descriptor such as Fukui functions are calculated to explain the chemical selectivity or reactivity site in PN4MPN. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra.
Collapse
Affiliation(s)
- N R Sheela
- Department of Applied Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602 105, India
| | | | | | | |
Collapse
|
23
|
Vijaya Chamundeeswari SP, James Jebaseelan Samuel E, Sundaraganesan N. Structural, vibrational, electronic and NMR spectral analysis of 3-chloro-6-methoxypyridazine by DFT calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 110:36-45. [PMID: 23557772 DOI: 10.1016/j.saa.2013.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 12/15/2012] [Accepted: 03/03/2013] [Indexed: 06/02/2023]
Abstract
In this work, the FT-Raman and FT-Infrared spectra of 3-chloro-6-methoxypyridazine sample were measured to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm(-1) and 4000-400 cm(-1), respectively. The molecular geometry and vibrational frequencies of 3-chloro-6-methoxypyridazine in the ground state were calculated using the DFT/B3LYP/6-31G(d),6-311G(d,p) level. The recorded FT-IR and FT-Raman spectral measurements favor the calculated structural parameters which are further supported by spectral simulation. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The UV-Visible absorption spectrum of the compound that dissolved in methanol was recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. The isotropic chemical shift computed by (13)C and (1)H NMR analysis also shows good agreement with experimental observations. In addition, the molecular electrostatic potential (MEP) and frontier molecular orbitals (FMOs) analysis of the title compound were investigated using theoretical calculations.
Collapse
Affiliation(s)
- S P Vijaya Chamundeeswari
- Photonics, Nuclear & Medical Physics Division, School of Advanced Sciences, VIT University, Vellore 632 014, Tamil Nadu, India
| | | | | |
Collapse
|
24
|
Sheela NR, Sampathkrishnan S, Thirumalai Kumar M, Muthu S. Synthesis, spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 109:272-281. [PMID: 23542518 DOI: 10.1016/j.saa.2013.03.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 02/25/2013] [Accepted: 03/03/2013] [Indexed: 06/02/2023]
Abstract
The title compound, 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone (2HPN4MPN) was synthesized and characterized by FT-IR, FT-Raman, UV-Vis and (1)HNMR, (13)CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The most stable conformer of 2HPN4MPN is identified from the computational results. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The UV-Vis spectrum was recorded in chloroform solution. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements the experimental findings. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. In addition, DFT calculations of the compound, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and non-linear optical (NLO) properties are performed at B3LYP/6-311++G(d,p) level of theory. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra.
Collapse
Affiliation(s)
- N R Sheela
- Department of Applied Physics, Sri Venkateswara College of Engineering, Sriperumbudur 602 105, India
| | | | | | | |
Collapse
|
25
|
Balachandran V, Karunakaran V. Quantum mechanical study of the structure and vibrational spectroscopic (FT-IR and FT-Raman), first-order hyperpolarizability, NBO and HOMO-LUMO studies of 4-bromo-3-nitroanisole. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 106:284-298. [PMID: 23416886 DOI: 10.1016/j.saa.2012.12.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 12/17/2012] [Accepted: 12/21/2012] [Indexed: 06/01/2023]
Abstract
The FT-IR and FT-Raman spectra of 4-bromo-3-nitroanisole (BNA) molecule have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. Optimized geometrical structure, harmonic vibrational frequencies, intensities, reduced mass, force constants and depolarization ratio have been computed by ab initio HF and the B3LYP density functional levels using 6-311++G (d,p) basis set. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The first-order hyperpolarizability (β) of the investigated molecule were computed using DFT calculations. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and analyzed. The influences of bromine atom, nitrile group and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed.
Collapse
Affiliation(s)
- V Balachandran
- PG and Research Department of Physics, A A Government Arts College, Musiri, Tiruchirappalli 621 211, India.
| | | |
Collapse
|
26
|
Poiyamozhi A, Sundaraganesan N, Karabacak M, Tanrıverdi O, Kurt M. The spectroscopic (FTIR, FT-Raman, UV and NMR), first-order hyperpolarizability and HOMO–LUMO analysis of 4-amino-5-chloro-2-methoxybenzoic acid. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
27
|
Ramalingam S, Periandy S. Spectroscopic investigation, computed IR intensity, Raman activity and vibrational frequency analysis on 3-bromoanisole using HF and DFT (LSDA/MPW1PW91) calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:835-843. [PMID: 21216183 DOI: 10.1016/j.saa.2010.12.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 12/08/2010] [Accepted: 12/10/2010] [Indexed: 05/30/2023]
Abstract
In this work, the experimental and theoretical spectra of 3-bromoanisole (3-BA) are studied. FT-IR and FT-Raman spectra of title molecule in the liquid phase have been recorded in the region 4000-100 cm(-1). The structural and spectroscopic data of the molecule in the ground state have been calculated by using Hartree-Fock and density functional method (LSDA and MPW1PW91) with the 6-31G (d, p) and 6-311G (d, p) basis sets. The vibrational frequencies are calculated and scaled values have been compared with the experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found in good agreement. The DFT-LSDA/6-311G (d, p) calculations have been found are more reliable than the ab initio HF/6-31G (d, p) calculations for the vibrational study of 3-BA. The optimized geometric parameters (bond lengths and bond angles) are compared with experimental values of the molecule. The alteration of vibrational bands due to the substitutions in the base molecule is also investigated from their characteristic region of linked spectrum.
Collapse
|
28
|
Krishnakumar V, Prabavathi N. Structure and vibrational frequencies of 6,7-dimethoxy-1,4-dihydro-1,3-quinoxalinedione based on density functional theory calculations: The role of pi-electron conjugation and back-donation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 77:238-247. [PMID: 20538512 DOI: 10.1016/j.saa.2010.05.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 04/27/2010] [Accepted: 05/15/2010] [Indexed: 05/29/2023]
Abstract
This work deals with the vibrational spectroscopy of 6,7-dimethoxy-1,4-dihydro-1,3-quinoxalinedione by means of quantum chemical calculations. The mid and far FT-IR and FT-Raman spectra are recorded in the condensed State. The fundamental vibrational frequencies and intensity of vibrational bands are evaluated using density functional theory (DFT) with the standard B3LYP/6-31G* method and basis set combination and is scaled using various scale factors which yields a good agreement between observed and calculated frequencies. The vibrational spectrum is interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results of the calculations are applied to simulate infrared and Raman spectra of the title compounds, which showed excellent agreement with the observed spectra. The infrared unscaled frequencies and intensities are used to disentangle the role played by back-donation in the title compound. For this purpose five other molecules are considered as references: ethane, dimethyl ether, anisole, p-nitro-anisole, and p-hydroxyanisole, in which back-donation has already been ascertained also experimentally. From the study of infrared intensities it is shown that no back-donation of electrons from the oxygen lone pairs takes place, independently of the conformation of the methoxy-group.
Collapse
Affiliation(s)
- V Krishnakumar
- Department of Physics, Periyar University, Salem 636 011, India
| | | |
Collapse
|
29
|
Subramanian N, Sundaraganesan N, Jayabharathi J. Molecular structure, spectroscopic (FT-IR, FT-Raman, NMR, UV) studies and first-order molecular hyperpolarizabilities of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine by density functional method. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 76:259-269. [PMID: 20413344 DOI: 10.1016/j.saa.2010.03.033] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 05/29/2023]
Abstract
Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine [vanillin azine (VA)] were carried out by using density functional (DFT/B3LYP) method with 6-31G(d) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment (mu) and the first hyperpolarizability (beta) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the VA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of VA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The theoretical NMR chemical shifts complement with experimentally measured ones.
Collapse
Affiliation(s)
- N Subramanian
- Govt College of Education, Komarapalayam 638183, Tamil Nadu, India
| | | | | |
Collapse
|
30
|
Krishnakumar V, Prabavathi N. Simulation of IR and Raman spectra of p-hydroxyanisole and p-nitroanisole based on scaled DFT force fields and their vibrational assignments. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2009; 74:154-161. [PMID: 19523872 DOI: 10.1016/j.saa.2009.05.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 05/10/2009] [Accepted: 05/18/2009] [Indexed: 05/27/2023]
Abstract
This work deals with the vibrational spectroscopy of p-hydroxyanisole (PHA) and p-nitroanisole (PNA) by means of quantum chemical calculations. The mid and far FT-IR and FT-Raman spectra were recorded in the condensed state. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) with the standard B3LYP/6-31G* method and basis set combination and were scaled using various scale factors which yield a good agreement between observed and calculated frequencies. The vibrational spectra were interpreted with the aid of normal coordinate analysis based on scaled density functional force field. The results of the calculations were applied to simulate infrared and Raman spectra of the title compounds, which showed excellent agreement with the observed spectra.
Collapse
Affiliation(s)
- V Krishnakumar
- Department of Physics, Periyar University, Salem 636 011, India
| | | |
Collapse
|
31
|
Abraham JP, Sajan D, Shettigar V, Dharmaprakash S, Němec I, Hubert Joe I, Jayakumar V. Efficient π-electron conjugated push–pull nonlinear optical chromophore 1-(4-methoxyphenyl)-3-(3,4-dimethoxyphenyl)-2-propen-1-one: A vibrational spectral study. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2008.06.031] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
32
|
Sajan D, Abraham JP, Hubert Joe I, Jayakumar V, Aubard J, Faurskov Nielsen O. Molecular structure, vibrational spectra and first-order molecular hyperpolarizabilities of potential anti-cancer drug, combretastatin-A1. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2008.01.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
33
|
James C, Pettit GR, Nielsen OF, Jayakumar VS, Joe IH. Vibrational spectra and ab initio molecular orbital calculations of the novel anti-cancer drug combretastatin A-4 prodrug. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:1208-1216. [PMID: 18248845 DOI: 10.1016/j.saa.2007.10.052] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 10/22/2007] [Accepted: 10/31/2007] [Indexed: 05/25/2023]
Abstract
The NIR-FT Raman and FT-IR spectral studies of the novel antineoplastic and antiangiogenesis substance comprestatin A-4 prodrug (CA4P) were carried out. The equilibrium geometry, various bonding features and harmonic vibrational frequencies of CA4P have been investigated with the help of B3LYP density functional theory (DFT) method. The most preferred cis-configuration for its bioactivity has been demonstrated on the basis of torsional potential energy surface (PES) scan studies. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity, charge delocalization and mesomeric effects have been analyzed using natural bond orbital (NBO) analysis. Detailed assignments of the vibrational spectra have been made with the aid of theoretically predicted vibrational frequencies. The optimized geometry shows near-planarity of phenyl rings and perpendicular conformation of meta substituted methoxy group. The vibrational analysis confirms the differently acting ring modes, steric repulsion, pi conjugation and back-donation.
Collapse
Affiliation(s)
- C James
- Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala, India
| | | | | | | | | |
Collapse
|
34
|
Vijayakumar T, Hubert Joe I, Reghunadhan Nair C, Jayakumar V. Efficient π electrons delocalization in prospective push–pull non-linear optical chromophore 4-[N,N-dimethylamino]-4′-nitro stilbene (DANS): A vibrational spectroscopic study. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2007.10.033] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
35
|
Lambert M, Olsen L, Jaroszewski JW. Stereoelectronic effects on 1H nuclear magnetic resonance chemical shifts in methoxybenzenes. J Org Chem 2007; 71:9449-57. [PMID: 17137372 DOI: 10.1021/jo061757x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Investigation of all O-methyl ethers of 1,2,3-benzenetriol and 4-methyl-1,2,3-benzenetriol (3-16) by 1H NMR spectroscopy and density-functional calculations disclosed practically useful conformational effects on 1H NMR chemical shifts in the aromatic ring. While the conversion of phenol (2) to anisole (1) causes only small positive changes of 1H NMR chemical shifts (Delta delta < 0.08 ppm) that decrease in the order Hortho > Hmeta > Hpara, the experimental O-methylation induced shifts in ortho-disubstituted phenols are largest for Hpara, Delta delta equals; 0.19 +/- 0.02 ppm (n = 11). The differences are due to different conformational behavior of the OH and OCH3 groups; while the ortho-disubstituted OH group remains planar in polyphenols due to hydrogen bonding and conjugative stabilization, the steric congestion in ortho-disubstituted anisoles outweighs the conjugative effects and forces the Ar-OCH3 torsion out of the ring plane, resulting in large stereoelectronic effects on the chemical shift of Hpara. Conformational searches and geometry optimizations for 3-16 at the B3LYP/6-31G** level, followed by B3LYP/6-311++G(2d,2p) calculations for all low-energy conformers, gave excellent correlation between computed and observed 1H NMR chemical shifts, including agreement between computed and observed chemical shift changes caused by O-methylation. The observed regularities can aid structure elucidation of partly O-methylated polyphenols, including many natural products and drugs, and are useful in connection with chemical shift predictions by desktop computer programs.
Collapse
Affiliation(s)
- Maja Lambert
- Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | | | | |
Collapse
|
36
|
Panicker CY, Varghese HT, Philip D, Nogueira HIS, Castkova K. Raman, IR and SERS spectra of methyl(2-methyl-4,6-dinitrophenylsulfanyl)ethanoate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:1313-20. [PMID: 17196427 DOI: 10.1016/j.saa.2006.09.042] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Accepted: 09/20/2006] [Indexed: 05/13/2023]
Abstract
Methyl(2-methyl-4,6-dinitrophenylsulfanyl)ethanoate was prepared by nucleophilic substitution. FT-IR and FT-Raman spectra of methyl(2-methyl-4,6-dinitrophenylsulfanyl)ethanoate were recorded and analyzed. Surface-enhanced Raman scattering (SERS) spectrum was recorded on a silver colloid. The vibrationl wavenumbers were computed by density functional theoretical (DFT) computations at the B3LYP/6-31G* level and they were found to be in good agreement with the experimental values. The molecule is adsorbed on the silver surface with the benzene ring in a 'tilted orientation'.
Collapse
Affiliation(s)
- C Yohannan Panicker
- Department of Physics, TKM College of Arts and Science, Kollam, Kerala 691005, India.
| | | | | | | | | |
Collapse
|
37
|
Yamakita Y, Isogai Y, Ohno K. Large Raman-scattering activities for the low-frequency modes of substituted benzenes: Induced polarizability and stereo-specific ring-substituent interactions. J Chem Phys 2006; 124:104301. [PMID: 16542073 DOI: 10.1063/1.2163344] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The large nonresonant Raman-scattering activities of the out-of-plane bending and torsional modes of monosubstituted benzene analogs are studied by low-frequency Raman experiments and B3LYP6-31++G(d,p) calculations. Electronic interactions between the sigma orbitals of the substituent and the pi orbitals of the ring are found to enhance the Raman activities, depending on the substituent and its conformation. In the case of tert-butylbenzene [C6H5C(CH3)3] and trimethylphenylsilane [C6H5Si(CH3)3], three single bonds which are linked to the alpha atom of the substituent have low rotational barriers around the joint bond. Nearly free rotation of the substituents leads to a significant probability for one of the single bonds to occupy a conformation close to the vertical configuration with respect to the ring at room temperature. The resultant sigma-pi electronic interaction gives rise to the large Raman activities. In contrast, those possessing a single bond in a coplanar (or nearly coplanar) configuration at the most stable equilibrium state, i.e., anisole (C6H5OCH3), thioanisole (C6H5SCH3), and N-methylaniline (C6H5NHCH3), display no prominent Raman bands for the low-frequency vibrational modes. In these molecules, the sigma-pi conjugation does not take place due to the orthogonal orientation of the orbitals. Strong conformational dependence of the sigma-pi Raman enhancement is clearly obtained for the metastable vertical conformer of thioanisole, for which Raman activities are one-order magnitude greater than those of the coplanar conformer.
Collapse
Affiliation(s)
- Yoshihiro Yamakita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Sendai 980-8578, Japan.
| | | | | |
Collapse
|
38
|
Yi JT, Ribblett JW, Pratt DW. Rotationally Resolved Electronic Spectra of 1,2-Dimethoxybenzene and the 1,2-Dimethoxybenzene−Water Complex. J Phys Chem A 2005; 109:9456-64. [PMID: 16866394 DOI: 10.1021/jp053254l] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rotationally resolved S(1) <-- S(0) electronic spectra of 1,2-dimethoxybenzene (DMB) and its water complex have been observed and assigned. The derived values of the rotational constants show that the bare molecule has a planar heavy-atom structure with trans-disposed methoxy groups in its ground and excited electronic states. The transition of DMB is polarized along the b-axis bisecting the methoxy groups, demonstrating that its S(1) state is an (1)L(b) state. Higher energy bands of DMB are also polarized along the b-axis and have been tentatively assigned to different vibrational modes of the (1)L(b) state. The water complex origin appears 127 cm(-1) to the blue of the bare molecule origin. Analyses of the high resolution spectra of DMB/H(2)O and DMB/D(2)O suggest that the water molecule is attached via two O-H...O hydrogen bonds to the methoxy groups in both electronic states. A tunneling motion of the attached water molecule is revealed by a splitting of these spectra into two subbands. Potential barriers to this motion have been determined.
Collapse
Affiliation(s)
- John T Yi
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | | | | |
Collapse
|
39
|
Spectroscopic behaviour, bond properties and charge distribution in methoxy groups in hydrofluoroethers: the effect of neighbouring CF2 group. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/j.theochem.2004.07.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
40
|
Surprisingly regular structure–property relationships between C–O bond distances and methoxy group torsional potentials: An ab initio and density functional study. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0166-1280(03)00413-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
41
|
Gellini C, Moroni L, Muniz-Miranda M. High Overtones of the C−H Stretching Vibrations in Anisole and Thioanisole. J Phys Chem A 2002. [DOI: 10.1021/jp020691g] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cristina Gellini
- Dipartimento di Chimica, Universita' di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Firenze, Italy
| | - Laura Moroni
- Dipartimento di Chimica, Universita' di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Firenze, Italy
| | - Maurizio Muniz-Miranda
- Dipartimento di Chimica, Universita' di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Firenze, Italy
| |
Collapse
|
42
|
Conformation, structure and molecular solvation: a spectroscopic and computational study of 2-phenoxy ethanol and its singly and multiply hydrated clusters. Chem Phys 2002. [DOI: 10.1016/s0301-0104(02)00498-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
43
|
Vibrational spectra and conformational isomerism of calixarene building blocks. III. 2,6-Dimethylanisole and n-propyl-2,6-dimethylphenyl ether. J Mol Struct 2002. [DOI: 10.1016/s0022-2860(02)00025-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|