Journal of Research in Science Vol. 2, December 2014, pp. 101-103
ISSN: 2278-9073
Density Functional Theoretical Computations of 1-benzothiazoyl-3-phenyl-2propenone C. Anubaa, B. Jini Kumarib, S. P. Selvin Pragalath Paulb & T. F. Abbs Fen Rejib* a
Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil - 629003, Tamilnadu, India
b
Department of Chemistry & Research Centre, Nesamony Memorial Christian College, Marthandam - 629165, Tamilnadu, India Email:
[email protected]
1-Benzothiazoyl-3-phenyl-2-propenone is a chalcone found to have antioxidant and anticancer activities. FT-IR spectra of 1-benzothiazoyl-3-phenyl-2-propenone have been recorded and analyzed. Theoretical information on the optimized geometry of the molecule were obtained by means of Density Functional Theory (DFT) using standard B3LYP/6-31G basis sets with Gaussian ’09 software package. The optimized geometric bond length, bond angle, dihedral angle and dipole moment of the molecule were calculated and compared with experimental values. With the help of different scaling factors, the observed vibrational wave numbers in FT-IR were assigned to different normal modes of the molecule. Most of the modes have wave numbers in the expected range.
Keywords: FT-IR, Gaussian, DFT, B3LYP, Mulliken charges, HOMO, LUMO
During the last decade, a large number of hybrid chalcone conjugates was synthesized and found to possess several therapeutic applications. Due to the presence of enone functionality in chalcone moiety, confers biological activity upon it, like antiinflammatory1, antifungal2, antioxidant3, 4 5 antimalarial , antituberculosis , analgesic6, anti HIV7 and antitumor8 activities. The natural chalcone, licochalcone A isolated from Chinese licorice roots was revealed to exhibit potential antimalarial activity9. The hybrid chalcone was found to possess potent anticancer activity permitting lower dose and better toxicological profile required for the possible therapeutic applications. These important pharmacophores can be accessed by modification of the basic chalcone system with heterocyclic, polyaromatic or organometallic structures10. In the present work, we report the synthesis of novel hybrid chalcones and an additional attempt was made to study the optimized geometry of the molecule were obtained by means of Density Functional Theory using standard B3LYP/6-31G basis sets with Gaussian ’09 Software Package.
Gaussian ’09 Software Package. Results and Discussions Molecular Structure Analysis The optimized molecular geometry of the molecule 1-benzothiazoyl-3-phenyl-2-propenone calculated using Guassian ’09 as shown in fig.1. The Self-Consistent Field (SCF) energy of 1benzothiazoyl-3-phenyl-2-propenone at B3LYP level with the basis set 6-31G is found to be 1144.5029a.u; with dipole moment value 3.6425 Debye. The bond lengths of C2-C3, C4-C5, C1-C6, N29-C7, C12-O13, C15-C14, C19-C18, C20-C23 and C21-C25 shows double bond character similarly the bond length of C3-C4, C5-C6, C1-C2, C7-S30, C7-C12, C12-C14, H17-C15, C15-C18, C19-C21, C25-C23 and C19-C21 shows single bond characters.
Experimental and Computational details Condensation of variously substituted 2Acetylbenzothiazole and Aromatic aldehyde furnished the corresponding Chalcones. The geometry and vibrational frequencies of the title compound 1-benzothiazoyl-3-phenyl-2-propenone has been optimized with the help of B3LYP/6-31G Density Functional Theory (DFT) method using —————— *Corresponding author
Figure 1: Optimized structure of 1-benzothiazoyl-3-phenyl-2propenone
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Mulliken Atomic Charges Mulliken atomic charge calculation has an important role in the application of quantum chemical calculation to molecular system because of atomic charges effect dipole moment, molecular polarizability, electronic structure and more a lot of properties of molecular systems. The bonding capability of a molecule depends on the electronic charge on the chelating atoms. The atomic charge values have been obtained by mulliken population analysis. To validate the reliability of our results, the mulliken population analysis of 1-benzothiazoyl-3phenyl-2-propenone has been calculated using B3LYP/6-31G basis set. The mulliken atomic charge of sulphur carries positive charge. Nitrogen carries negative charge (-0.469). Carbon atom carries both positive and negative charge. The oxygen atom carries negative charge (-0.291e).
ISSN: 2278-9073
with literature values reveal that the B3LYP method shows very good agreement with the literature observation.
E = -0.23854 a.u. (HOMO)
HOMO-LUMO The electronic properties of molecule are related to the geometry of isolated molecule but they provide a lot of information about macroscopic properties of molecular system in condensed phases. In fact all the features discussed above can be rested in terms of HOMO and LUMO. There are several ways to calculate the excitation energies and the simplest one, involves the difference between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) of neutral system. LUMO is an electron acceptor that represents the ability to obtain an electron and HOMO represents the ability to donate an electron. The relative energy of the molecular orbital has been calculated and a graphical representation of HOMO-LUMO of 1-benzothiazoyl-3-phenyl-2propenone is given in figure 2. The energies of HOMO-LUMO are: -0.23854a.u; -0.09363 respectively and energy gap ΔE is 0.33217a.u; (ΔE reveals the chemical activity of the molecule). The HOMO-LUMO energy gap of 1-benzothiazoyl-3phenyl-2-propenone have been calculated at the B3LYP/6-31G level. Vibrational assignments In order to obtain the spectroscopic signature of the title compound, we performed a frequency calculation analysis. Vibrational frequencies were calculated by using B3LYP/6-31G method. 1benzothiazoyl-3-phenyl-2-propenone molecule consists of 30 atoms therefore it got 84 normal modes of vibrations. Comparison of the frequencies calculated at DFT method using 6-31G basis set
E = -0.09363 a.u. (LUMO)
Figure 2: HOMO-LUMO of 1-benzothiazoyl-3-phenyl-2propenone
C-H Vibrations The aromatic structure shows the presence of CH stretching vibrations in the region 3100-3000cm-1 which is the characteristic region for the ready identification of the C-H stretching vibrations11-13. The C-H stretching vibration computed by B3LYP/6-31G method good agreement with literature observation. The C-H in-plane bending vibrations were observed in the region 14201000cm-1. These bands represent the C-H in-plane– bending vibrations. In the present work, the theoretical calculation indicates the unscaled frequency value at 1480 cm-1 is assigned to C-H inplane-bending vibration. The presence of C-H out-of plane vibrations were observed in the region 999750cm-1.In the present work, the C-H out-of-plane bending vibration computed by B3LYP/3-21G method good agreement with literature observation. Ring vibrations Generally, the carbon-carbon stretching vibration in aromatic compound from the band is in the region 1650-1430cm-1. In the present study, the unscaled frequency values at 1670cm-1and 1640cm-1 are assigned to carbon-carbon stretching vibration.
C. Anuba, B. Jini Kumari, S. P. Selvin Pragalath Paul & T. F. Abbs Fen Reji: Density Functional Theoretical computations of 1-benzothiazoyl-3-phenyl-2-propenone
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C-N vibrations
Acknowledgement
The identification of C-N vibrations is a difficult task, since the mixing of vibrations is possible in this region 1600-1500cm-1. In the present work, the C-N stretching vibration show good agreement with theoretically computed (unscaled) values at 1545cm1 by B3LYP/6-31G basis set.
S. P. Selvin Pragalath Paul acknowledges University Grants Commission, SERO, Hyderabad for financial assistance in the form of Minor Research Project [F.MRP-5354/14 (SERO/UGC)]. T. F. Abbs Fen Reji thank University Grants Commission, New Delhi for financial assistance in the form of Major research Project [F.No. 41229/2012 (SR)]. The authors thank NIIST, Trivandrum and CDRI, Lucknow for spectral and analytical data.
C-S vibrations The C-S stretching vibration is expected in the region 710-685cm-1. While DFT calculations give the C-S stretching vibration at 663cm-1 is assigned to C-S stretching vibration. Cabonyl group vibrations The carbonyl group is important and its characteristic frequency has been extensively used to study a wide range of compounds. The C=O stretching frequency appears strongly in the range 1850-1600cm-1. The DFT calculations give C=O stretching mode at 1690cm-1 is assigned to carbonyl group vibration. The C=O bending vibrations computed by B3LYP/6-31G method good agreement with literature observation. Conclusion The structure of 1-benzothiazoyl-3-phenyl-2propenone was optimized by the DFT methods using the basis sets 6-31G. Using the optimized geometry, the vibrational frequencies, have been found to agree well with the literature reported values. The energy of Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) is also made.
References 1 Ballesteros, J. F.; Sanz, M. J.; Ubenda, A.; Miranda, M. A.; Iborra, S.; Paya, M.; Alcaraz, M., J. Med. Chem., 1995, 38, 2794. 2 Go, M. L.; Wu, X.; Liu, X. L., Curr. Med. Chem., 2005, 12, 483. 3 Mukerjee, V. K.; Prased, A. K.; Raj, A. G.; Brakhe, M. E.; Olsen, C. E.; Jain, S. C.; Parmer, V. P. Bioorg. Med. Chem., 2001, 9, 337. 4 Liu, U. M.; Wilairat, P.; Croft, S. L.; Tan, A. L.; Go, M., Bioorg. Med. Chem., 2003, 11, 2729. 5 Siva Kumar, P. M.; Geetha Babu, S. K.; Mukesh, D. Chem. Pharm. Bull., 2007, 55, 44. 6 Viana, G. S.; Bandeira, M. A.; Mantos, F. J. Phytomed., 2003, 10, 189. 7 Tiwari, N.; Dwivedi, B.; Nizamuddin, K. F.; Nakanshi, Y.; Lee, K. H., Bioorg. Med. Chem., 2000, 10, 699. 8 Ducki, S.; Forrest, R.; Hadfield, J. A.; Kendall, A.; Lawrence, N. J.; Mc-Gown, A. T.; Rennison, D., Bioorg. Med. Chem., 1998, 8, 1051. 9 Warare, G.; Aher, R.; Kawathekar, N.; Renjan, R.; Kaushik, N. K.; Sahal, D., Bioorg. Med. Chem. Lett.., 2010, 420, 4675. 10 Violeta, M.; Nevena, D.; tatjana, S.; Branka, K.; Dusan, S.; Mivosleva, V.; Barbara, J.; Nikola, T.; Milka, P.; Vesna, T.; Jadranka, A.; Milan, D., Eur. J. Med. Chem., 2013, 89, 402. 11 Kuwae, A.; Machida, K., Spectrochim. Acta A, 1979, 35, 841. 12 Green, J. H. S.; Harrison, D. J., Spectrochim. Acta A, 1976, 32, 1279. 13 Sinta, S. P.; Chatterjee, C. L., Spectrosc. Lett., 1976, 9 461.
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