Crystallography and magnetism of radicals with hindered hydroxyl groups: 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl and 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl.
Radicals form networks of OH... ON and OH...Me(nitroxide) interactions. In 2, a frustrated network forms with insufficient N-O units to form extended chain interactions. The magnetism of 1 fits a 1-D Heisenberg model with J/k=-25 J mol(-1), while 2 shows more complex exchange behaviour consistent with its disordered crystal lattice.
Aminophenylnitronylnitroxides: Highly Networked Hydrogen-Bond Assembly in Organic Radical Materials
2-(Meta-aminophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (mAPN) and 2-(para-aminophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (pAPN) were synthesized and subjected to magnetostructural analysis. Both form extended hydrogen bonding networks involving both amino NH bonds to radical spin-density bearing nitronylnitroxide NO groups. Their crystallographic assembly motifs and magnetic exchange properties are compared to those of tert-butoxylcarbonyl (BOC) and amide derivatives having only one NH bond. The conversion of pAPN to acid salt derivatives gives a solid that is essentially diamagnetic, although dissolution of the solid shows the radical spin units to be preserved.
Analysis of Macro and Micronutrients in Soils from Palestine Using Ion Exchange Membrane Technology
Ion Exchange membrane technology (IEM) is a method that allowed a single extraction process and a single subsequent measurement of different elements that are available in soil. The values of the available forms of the different macro- and micronutrients obtained by IEM extraction were compared with the values of the soluble form obtained by conventional extraction methods. In surface soil sample, the concentrations of available potassium, nitrate, phosphate, iron and boron were 37.7 mg kg–1, 17.5 mg kg–1, 3.6 mg kg–1, 171.0 μg kg–1, and 4.2 μg kg–1 respectively were greater than that of soluble forms of the same elements which were 7.0 mg kg–1, 9.2 mg kg–1, 0.4 mg kg–1, 109.0 μg kg–1, and 1.9 μg kg–1 respectively.