甲巯咪唑互变异构和振动光谱的密度泛函理论研究
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摘要
甲巯咪唑(MMI)是一种广泛应用于临床治疗的抗甲状腺药物。它有硫醇式和硫酮式两种互变异构体,利用密度泛函理论中的B3LYP混合泛函方法和6-311+G(d,p)基函数组,计算了两种结构的吉布斯自由能。结果表明,硫酮式结构的能量最低,是最稳定的结构。针对硫酮式结构,采用GAR2PED程序得到了MMI分子各振动频率的势能分布,并结合实验测定的数据对各振动频率归属做出了全面地指认,弥补了以往文献未能充分考虑互变异构对振动频率归属影响的缺憾,提供了MMI分子振动光谱的新信息,有益于对与之相关衍生物光谱性质的进一步研究。
2-mercapto-1-methylimidazole( MMI) is a kind of important anti-thyroid drug widely used in clinical treatment. MMI exists in thiol and thione tautomeric forms. In order to make sure which one is the stable structure,the calculation of Gibbs free energy was performed by the B3LYP method with the 6-311+G( d,p) basis set. The results showed that the thione form was the right one we want to find. As a follow-up work,molecular potential energy of each frequency distribution was obtained using the program GAR2PED,and the overall recognition of the vibration frequency assignment was made considering the experimental data. Previous literature didn' t consider the impact of tautomerism,so such kind of work can provide more information about the molecular vibrational spectra of MMI and is useful for the further study on spectral properties of the related derivative.
2-mercapto-1-methylimidazole( MMI) is a kind of important anti-thyroid drug widely used in clinical treatment. MMI exists in thiol and thione tautomeric forms. In order to make sure which one is the stable structure,the calculation of Gibbs free energy was performed by the B3LYP method with the 6-311+G( d,p) basis set. The results showed that the thione form was the right one we want to find. As a follow-up work,molecular potential energy of each frequency distribution was obtained using the program GAR2PED,and the overall recognition of the vibration frequency assignment was made considering the experimental data. Previous literature didn' t consider the impact of tautomerism,so such kind of work can provide more information about the molecular vibrational spectra of MMI and is useful for the further study on spectral properties of the related derivative.
引文
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[2]Urquiza N M,Naso L G,Silvia G,et al.Manca antioxidant activity of methimazole-copper(II)bioactive species and spectroscopic investigations on the mechanism of its interaction with Bovine Serum Albumin[J].Polyhedron,2012,31(1):530-538.
[3]Kurzepa M,Dobrowolski J C,Mazurek A P.Theoretical studies on tautomerism and IR spectra of C-5 substituted imidazoles[J].Journal of Molecular Structure,2001,565/566(1/2/3):107-113.
[4]Zhu H J,Ren Y,Ren J,et al.DFT explorations of tautomerism of 2-mercaptoimidazole in aqueous solution[J].Journal of Molecular Structure:THEOCHEM,2005,730(1/2/3):199-205.
[5]Balachandran V,Lakshmi A,Janaki A.Ab initio,DFT,HOMO-LUMO and natural bond orbital analyses of the electronic structure of 2-mercapto-1-methylimidazole[J].Journal of Molecular Structure,2011,1006(1/2/3):395-401.
[6]Biswas N,Thomas S,Sarkar A,et al.Adsorption of methimazole on silver nanoparticles:FTIR,raman,and surface-enhanced raman scattering study aided by density functional theory[J].J Phys Chem C,2009,113(17):7091-7100.
[7]Zou Q,Jiang L,Du X,et al.Optimization of phenanthrene structure and vibrational spectra studies based on density functional theory[J].Chin J Lumin,2012,33(12):1389-1397.
[8]谷明信,何国田,李明,等.1-乙基-3-甲基咪唑四氟硼酸盐光谱分析与计算[J].重庆师范大学学报:自然科学版,2011,28(6):56-60.Gu M X,He G T,Li M,et al.Spectral analysis and calculations of 1-ethyl-3-methyl imidazole tetrafluoroborate[J].Journal of Chongqing Normal University:Natural Science,2011,28(6):56-60.
[9]Martin J M L,Alsenoy C V.Gar2ped[CP/OL].Belgium:University of Antwerp,1995.
[10]Frisch M J,Trucks G W,Schlegel H B,et al.Gaussian03[DB/CD].Revision C.02.Pittsburgh:Gaussian Inc,2003.
[11]Garner M,Armstrong D R,Reglinski J,et al.The structure of methimazole and its consequences for current therapeutic models of Graves'disease[J].Bioorganic Medicinal Chemistry Letters,1994,4(11):1357-1360.
[12]Pulay P,Fogarasi G,Pongo G,et al.Combination of theoretical ab initio and experimental information to obtain reliable harmonic force constants.Scaled quantum mechanical(QM)force fields for glyoxal,acrolein,butadiene,formaldehyde,and ethylene[J].J Am Chem Soc,1983,105(24):7037.
[13]Fogarasi G,Xhov X,Taylor P W,et al.The calculation of ab initio molecular geometries:efficient optimization by natural internal coordinates and empirical correction by offset forces[J].J Am Chem Soc,1992,114(21):8191.
[14]Raper B S,Creighon J R.l-methyl-4-imidazoline-2-thione:structure,comparison with related molecules and a discussion of coordination characteristics[J].Acta Cryst,1983,B39(3):355-360.
[15]Andersson M P,Uvdal P.New scale factors for harmonic vibrational frequencies using the B3LYP density functional method with the triple-úbasis set 6-311+G(d,p)[J].J Phys Chem A,2005,109(12):2937-2941.