Spectroscopic investigation, HOMO–LUMO energies, natural bond orbital (NBO) analysis and thermodynamic properties of two-armed macroinitiator containing coumarin with DFT quantum chemical calculations

Abstract

In the present work, two-armed macroinitiator containing coumarin were synthesized, characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance techniques and investigated theoretically using density functional theory (DFT) calculations. The molecular geometry, fundamental vibrational frequencies, atomic charges obtained from atomic polar tensors and Mulliken were analyzed by means of structure optimizations based on the DFT method with 6-31G+(d, p) as a basis set. The 1H chemical shifts were calculated by the gauge-including atomic orbital method and compared with available experimental data. The electronic properties, such as highest occupied molecular orbital – lowest unoccupied molecular orbital (HOMO–LUMO) energies, electron affinity, electronegativity, ionization energy, hardness, chemical potential, global softness, and global electrophilicity were calculated by using the DFT method. The electrostatic potential and molecular electrostatic potential surfaces were performed to predict the reactive sites of the two-armed macroinitiator. The energy difference between acceptor and donor and stabilization energy were determined using natural bond orbital analysis. The results show that the occurrence of intramolecular charge transfers within the polymer. Time-dependent density functional theory calculations of visible spectra were analyzed at different solvents. Finally, thermodynamic functions, such as enthalpy, heat capacity, and entropy, of the two-armed macroinitiator at different temperatures were calculated and the relationship with temperature was investigated.

Application of Hammett equation to intramolecular hydrogen bond strength in para-substituted phenyl ring of trifluorobenzoylacetone and 1-aryl-1,3-diketone malonates

“…The average energy difference between the HOMO and LUMO of the title molecules are in the 3.87-4.49 eV range (Tables 4 and 5). This energy gap indicates that the title molecules are very stable [52][53][54][55]. Our results show that there are good linear correlations between σp and the energy difference between HOMO and LUMO in the studied molecules, see Table 8 and Figure 3.…”

Physicochemical data of p-cresol, butyric acid, and ammonia

“…The molecular electrostatic potential maps (ESP) reveal electron-rich and electron-poor areas in a molecule, which may be used to visually analyze and predict the reactivity of a given molecule based on color-red being most negative and blue being the most positive [1], [2]. As can be seen from butyric acid's ESP (Fig.…”

Coumarin-based random copolymer

“…17 Most of the physical and chemical properties of monomer and polymer can be estimated by various computational methods. 18,19 In addition, by adding a monomeric unit to the polymer chain, the thermal properties of a polymer can be significantly modified. 20 This coumarin-based random copolymer can be used for the preparation of various photoresponsive polymers, which has become the focus of interest, as well as thermal decomposition and theoretical studies on designing polymers containing coumarin using the DFT method.…”