A Characterization Study on 4-Amino-3,5-Dialkyl-1-Triazole by Density Functional Theory and Ab Initio Hartree-Fock Calculations

Ordu Üniv. Bil. Tek. Derg., Cilt:1, Sayı:1,2011,36-49 Ordu Univ. J. Sci. Tech., Vol:1, No:1, 2011,36-49 A CHARACTERIZATION STUDY ON 4-AMINO-3,5-DIALKYL-1-TRIAZOLE BY DENSITY FUNCTIONAL THEORY AND AB INITIO HARTREE–FOCK CALCULATIONS Yusuf ZALAOGLU1 Gürcan YILDIRIM2 Asaf Tolga ULGEN2,3 Barış GUNER4 Cabir TERZIOGLU2 1 Osmaniye Korkut Ata University, Department of Physics, Osmaniye–Turkey, 80000 2 Abant Izzet Baysal University, Department of Physics, Bolu–Turkey, 14280 3 Sirnak University, Electrical and Electronics Engineering Faculty, Sirnak–Turkey, 73000 4 Rize University, Department of Physics, Rize–Turkey, 53100 Özet 4-Amino-3,5-Dialkyl-1-Triazole molekülünün karakterizesi için, bağ uzunluklarını ve açılarını içeren temel haldeki optimize moleküler yapısı, 6–31G (d,p) temel setli yoğunluk fonksiyon metodu (DFT) ve ab initio Hartree–Fock (HF) kuantum hesaplama yöntemleri ile incelenmiştir. Hesaplanan bağ uzunlukları ve bağ açıları birbirleriyle ile iyi bir uyum içinde olduğu gözlenmiştir. Molekülün kimliği için ayrıca; atomik yükler, termodinamik nicelikler, nükleer magnetik rezonans ve mor ötesi spektrumları belirlendi ve yorumlandı. Teorik 13C and 1H kimyasal kaymalar mevcut deneysel verileri ile iyi bir uyuma sahip olduğunu görüldü. Buna ek olarak da hem sınır orbital (FMO) ve elektrostatik potansiyel enerji değerleri (MEP) simüle edildi, hem de enerji geçiş durumları ve bant enerjileri değerlendirildi. Anahtar Kelimeler: 4-Amino-3,5-Dialkyl-1-Triazole, FMO, MEP, HF, DFT 4-AMİNO-3,5-DİALKYL-1-TRİAZOLE MOLEKÜLÜNÜN AB İNİTİO HARTREEFOCK (HF) VE YOĞUNLUK FONKSİYON TEORİSİ (DFT) HESAPLAMALARI İLE KARAKTERİZE EDİLMESİ Abstract The optimized molecular structures including bond lengths and angles of 4-Amino-3,5-Dialkyl1-Triazole molecule were investigated using Density Functional Theory (DFT) and ab initio Hartree–Fock (HF) quantum mechanical calculation methods at 6–31G (d,p) basis set in order to characterize the molecule. All the calculated bond lengths and bond angles were found to be in good agreement with each other. Moreover atomic charges, thermodynamic properties, nuclear magnetic resonance (NMR) spectra and ultraviolet visible (UV–Vis) spectra were determined and interpreted for the identification of the molecule. Theoretical 13C and 1H chemical shifts were shown to have a good agreement with available experimental determines. Furthermore, we not only simulated frontier molecular orbitals (FMO) and the molecular electrostatic potential (MEP) but evaluated the transition state and energy band gap. Key Words: 4-Amino-3,5-Dialkyl-1-Triazole, FMO, MEP, HF, DFT 36 A characterization study on 4-amino-3,5-Dialkyl-1-triazole by density functional theory and ab initio hartree-fock calculations 1. INTRODUCTION As it is well known, triazole one of a pair of isomeric chemical compounds has a fivemembered ring of two carbon atoms and three nitrogen atoms. Derivatives of this compound were thought that it undertook some vital assignments to continue the biological activity. Thus, the researches on triazole derivatives increase in the last decades due to the fact that the increased interest in not only the fundamental researches in heterocyclic chemistry and biology but the application in industry of these derivatives in the last decades stems from its pharmacological, insecticidal, fungicidal, herbicidal (Joshi et al., 1962; Hartwell and Abbot,1969; Kubota et al., 1978; Ikizler et al., 1996; Costales et al., 1998; Liu et al., 2000; Varma, 2000; Demirbas et al., 2002; Holla et al., 2002; Almasirad et al., 2004). In order to support the experimental evidences, the scientists use computational methods which are reliable to characterize the molecule because of their efficiency and accuracy with respect to the evaluation of a number of molecular properties (Ravikumar et al., 2008). A suitable quantum chemical study is helpful to predict compound properties economically and to clarify some experiment phenomena insightfully (Sun et al., 2010). In this respect, the computational researches on compound properties tend to increase (Fang et al., 2008 ; Avci et al., 2009; Karakurt et al., 2010). In this study, we calculated the molecular structures including bond lengths and angles, atomic charges, thermodynamic properties, NMR spectra and UV–Vis Spectra. Furthermore; after frontier orbitals and the molecular electrostatic potential were visualized, transition states and energy band gap were determined and interpreted for the 4Amino-3,5-Dialkyl-1-Triazole molecule by using quantum mechanical methods. The aim of this study is to not only clarify the characterization of 4-Amino-3,5-Dialkyl-1-Triazole but show the way to future studies of this molecule, as well. 2. COMPUTATIONAL DETAILS In order to predict compound properties economically and obtain the characterization of the 4-Amino-3,5-Dialkyl-1-Triazole molecule, the optimized molecular structures, atomic charges, thermodynamic properties, NMR Spectra, UV spectra, translation energy (HOMO– LUMO) and molecular electrostatic potential (MEP) were investigated by means of HF (Young, 2001) and B3LYP (Becke, 1992) methods at 6–31G(d,p) (Francl et al., 1982) basis set and then compared with each other. All the computations were performed by using Gaussian 09 package program with molecular visualization program (Gaussview et al., 2003 ; Frisch, M. J., et. al, 2009) on the personal computer. 3. RESULT AND DISCUSSION We determined the molecular geometry, thermodynamic properties, atomic charges, NMR spectra UV–Vis spectra, electrostatic potential and translation energy │ΔE│ for the identification of 4-Amino-3,5-Dialkyl-1-Triazole. 3.1. Molecular Geometry Essentially two internal rotating groups are present in the molecule. The first one is the amine group NH2, which can rotate about the bond N–H (N20–H21 and N20–H22 for amine group connected to N19 atom). The other rotate group is the methyl groups CH 3, which can rotate about C–C (C16–C23 for methyl groups C16–CH3 and C23–CH3, respectively). Therefore, there are many more possible conformers of the molecule. In this study, in order to find the most 37 Y. Zaloğlu, G. Yıldırım, A.T. Ulgen, B. Güner, C. Terzioğlu optimized geometry, the molecular energies of these tautomeric forms were calculated at different methods and various basis sets. The energy obtained in this study is minimum for the most optimized geometry. The most optimized molecular structures including bond lengths and bond angles of 4-Amino-3,5-Dialkyl-1-Triazole are shown in Figure 1 along with labeling and symbolizing by using schema. Geometric properties of structure were calculated by B3LYP/6– 31G(d,p) and HF/6–31G(d,p) levels of calculation and depicted in Table 1. As can be seen from the table, all calculated data are in good agreement with each other. The largest difference of the calculated geometries was found to be about 0.04 Å (C15-N17) for the bond lengths and 1.49 (C5-C6-C15) for the bond angles. Table 1. Ca (...truncated)