Pikrik Asit ile 2-aminofenol ve 4-aminofenol Arasında Oluşan Enerjik Ko-kristallerin X-ışını Kırınımı ve Kuantum Mekaniksel Hesaplama Yöntemleri ile İncelenmesi
Özet
The main purpose of this thesis is to investigate the energetic co-crystals formed by proton transfer between commonly used explosive picric acid (TNP, 2,4,6-trinitrophenol) [C6H2(NO2)3OH] and 2-aminophenol and 4-aminophenol [C6H4NH3OH] with experimental and quantum mechanical methods.
The co-crystals consisting of picric acid and aminophenol investigated in this thesis, first synthesized by Prof. Dr. Orhan ATAKOL (Department of Chemistry, Faculty of Science, Ankara University). Their crystal and molecular structures experimentally determined using x-ray single crystal diffraction (XRD) method.
For the ease of understanding within the scope of the thesis, co-crystals formed between picric acid (PA), 2-aminophenol (2A), and 4-aminophenol (4A) abbreviated as PA-2A-KK and PA-4A-KK, respectively.
The molecular formula of PA-2A-KK crystal is [C6H2(NO2)3OC6H4NH3OH] and it is in the triclinic crystal system, space group P-1, with unit cell parameters a = 8.1456(12) Å, b = 8.4827(12) Å, c = 10.3466(14) Å, α = 79.745(4)°, β = 82.017(4)°, and γ = 88.870(4)°. The molecular formula of PA-4A-KK crystal is [C6H2(NO2)3OC6H4NH3OHH2O] and one mole of water is integrated into the structure. The structure is in the monoclinic crystal system with space group P21/c and the unit cell parameters are a = 14.998(2) Å, b = 7.7882(12) Å, c = 13.1987(19) Å, and β = 109.481(5)°. The water molecule incorporated into the structure of PA-4A-KK contributes to forming and stabilizing the co-crystal structure between PA and 4A.
Quantum mechanical calculations performed for the gas phase of PA-2A-KK and PA-4A-KK co-crystals. The quantum mechanical calculations carried out for the structures obtained by placing PA, 2A, and 4A molecules close to each other without forming co-crystals. The abbreviations PA-2A-SM and PA-4A-SM used to refer to the free molecule states of PA with 2A and PA with 4A, respectively. The purpose of performing quantum mechanical calculations for the gas phase of these molecules is to investigate the properties of explosives that did not synthesized as single crystal using computational methods to test how closely the structural information matches the experimental results. The aim is to find physical and chemical information about the structures with theoretical calculations where the experimental study is not possible.
In thesis proposal, the research topic included the synthesis of co-crystals of picric acid and TNT molecules with 4A to investigate with experimental and quantum mechanical methods. Since, the co-crystal synthesis cannot be performed using TNT and 4A, as an extension of this study, theoretical studies can be conducted on the free molecules of TNT with 4A and TNT with 2A by comparing the experimental and theoretical results gathered in this thesis, to investigate the insights of the structures TNT-2A-SM and TNT-4A-SM.
In theoretical calculations, Hartree-Fock (HF), second-order Møller-Plesset perturbation theory (MP2), and Density Functional Theory (DFT) methods used. At the beginning, using 3-21G, 6-31G(d,p), and 6-311G(d,p) basis sets for each of HF, MP2, and DFT/B3LYP methods, single point energy (SPE) values calculated for PA-2A-KK and PA-4A-KK co-crystal molecules. Additionally, SPE values computed for PA-2A-SM and PA-4A-SM free molecules following their optimization results. Based on the obtained results, the most suitable method and basis set for the structures studied in the thesis found as DFT/B3LYP/6-311G(d,p). Using this method and basis set, molecular boundary orbitals (HOMO, LUMO) and binding energies calculated for the gas phase of PA-2A-KK and PA-4A-KK co-crystal molecules, as well as for PA-2A-SM and PA-4A-SM free molecules. Potential energy surfaces (PES) also drawn. For the solid phase of PA-2A-KK and PA-4A-KK co-crystals, Hirshfeld surface analysis performed with the CIF file obtained from XRD data, and fingerprint plots drawn. The stability of structures determined by comparing their reactivity parameters.
The input files for quantum mechanical calculations generated and results were analyzed with GaussView 5.0.9 software. Gaussian 09 software used for performing the calculations. Hirshfeld surface analysis of co-crystal structures carried out with CrystalExplorer21 software.
