The title compound exists as yellow （1Y） and red （1R） crystals, but both gave red solutions. The intermolecular interactions between the CN parts of the crystals in IY are very weak. By the mechanical crushing as ...The title compound exists as yellow （1Y） and red （1R） crystals, but both gave red solutions. The intermolecular interactions between the CN parts of the crystals in IY are very weak. By the mechanical crushing as well as in solution 1Y again becomes red due to the absence of intermolecular interactions. We explain this color behavior by crystallochromism and solvation chromism.展开更多
Several 3-aminoquinazolin-4-(3H)-one derivatives were synthesized and characterized.Using proton nuclear magnetic resonance (NMR) spectra,we have investigated the barriers to rotation around the N ― N bond as a funct...Several 3-aminoquinazolin-4-(3H)-one derivatives were synthesized and characterized.Using proton nuclear magnetic resonance (NMR) spectra,we have investigated the barriers to rotation around the N ― N bond as a function of temperature.Changes in the NMR spectra at high temperatures are explained in terms of hindered rotations of the N ― N bond.Free energies of activation for the rate determining stereochemical process were calculated to be as high as 67-75 kJ · mol-1.Ground state molecular geometries and vibrational frequencies were calculated using the HF/6-31G and B3LYP/6-31G level of theories.The optimized bond lengths and bond angles are in good agreement with experimental values at both theoretical levels.展开更多
基金support and facilities to carry out the research work provided by King Khalid University are greatly acknowledged
文摘The title compound exists as yellow （1Y） and red （1R） crystals, but both gave red solutions. The intermolecular interactions between the CN parts of the crystals in IY are very weak. By the mechanical crushing as well as in solution 1Y again becomes red due to the absence of intermolecular interactions. We explain this color behavior by crystallochromism and solvation chromism.
基金AL-AMRI Reem S. Abdulaziz was supported by the King Abdul Aziz City of Science and Technology (KACST) (GSP-18-138)
文摘Several 3-aminoquinazolin-4-(3H)-one derivatives were synthesized and characterized.Using proton nuclear magnetic resonance (NMR) spectra,we have investigated the barriers to rotation around the N ― N bond as a function of temperature.Changes in the NMR spectra at high temperatures are explained in terms of hindered rotations of the N ― N bond.Free energies of activation for the rate determining stereochemical process were calculated to be as high as 67-75 kJ · mol-1.Ground state molecular geometries and vibrational frequencies were calculated using the HF/6-31G and B3LYP/6-31G level of theories.The optimized bond lengths and bond angles are in good agreement with experimental values at both theoretical levels.
