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تحضير قواعد الازو - شف المشتقة من السالسلديهايد ومعقداتها مع اللانثانيدات واختبار سلوكها الحراري كبلورات سائلة == Synthesis of Schiff - base Derived from Salicylaldehyde with their Lanthanide Complexes and Examination of their Thermal Behavior as Liquid Crystals
Author name:
سديم محمد بدري البارودي
Supervisor name:
خليل خلف عبد التميمي
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Doctorate
University:
Mustansiriyah University - College Of Science
Language:
English
University location:
Baghdad
First pages:
25T1786 - p.pdf
Abstract:
In this work four ligands based on azobenzene mesogenic unit and their lanthanide complexes which could exhibit liquid crystalline behavior were synthesized and investigated. The four classes briefly described as follows : [H2L1] N - (2 - hydroxy phenyl) - 4 - n - butylsalicylaldimines) which prepared by the reaction of 5 - ((4 - Butyl phenyl) azo) - salicylaldehyde [AZO1] with 2 - Aminophenol. [H2L2] N, N - Di - (4 - butylsalicylidene) - 1,3 - diaminopropane by the reaction of [AZO1] with 1,3 - Diaminopropane in 2 : 1 molar ratio. [H2L3] Bis[{1 - (4 - Hydroxyphenylazo) - 2 - nitrobenzene}salicylidene] - 1,2 - benzene diamine by the reaction of 1 - (3 - Formyl - 4 - hydroxyphenylazo) - 2 - nitrobenzene [AZO2] with 2 - phenylenediamine in 2 : 1 molar ratio. [H2L4] Bis[{1 - (4 - hydroxyphenylazo) - 2 - nitrobenzene}salicylidene] - 1,3 - diamino propane by the reaction of [AZO2] with 1,3 - diaminopropane in 2 : 1 molar ratio.Lanthanide metal complexes of the prepared ligands of the type LnH2L1(HL1)2Cl, Ln(H2L2)L2Cl, LnH2L3Cl3 and Ln(H2L4)L4Cl, Ln= La+3, Ce +3, Sm+3 and Gd+3 were prepared and characterized.The ligands and complexes were characterized by 1H and 13CNMR, elemental analysis (C.H.N.O), FT - IR spectroscopy, GC - mass, Magnetic susceptibility, Molar Conductivity and Thermo gravimetric analysis (TGA).Investigation of complexes suggest that lanthanide ions react with H2L1 in 1 : 3 molar ratio and two ligands molecules behaves as tridentate and the third one as bidentate as it present in zwitter ionic form with an additional one chloro ion to complete nine coordination geometry.VIThe 1 : 2 molar ratio with H2L2 ligand shown one molecule behaves as tetradentate and bidentate for the other which were presents as zwitteric ion form with an additional one chloro ion to complete seven coordination geometry. The third lanthanide complexes H2L3 ligand were conformed with 1 : 1 molar ratio ligand, which behaves as tetradentate and an additional three chloro ions to complete seven coordination geometry. Lanthanide complexes H2L4 of 1 : 2 molar ratio, one ligand molecule behaves as tetradentate and bidentate for the other as it present in zwitter ionic and an additional chloro ion to complete seven coordination geometry.Differential scanning calorimetry (DSC) measurements and optical polarized microscopy (POM) were used to study the thermal behavior of the prepared ligands and lanthanide(III) complexes and indicated that : [H2L1] and the lanthanide(III) complexes are an enantiotropic liquid crystal exhibiting smectic - A (SmA) phases during heating to isotropic liquid (I) and the reverse cooling process to crystalline solid (Cr) exhibit as Smectic - A phase.[H2L2]and the lanthanide(III) complexes exhibit smectic - A (SmA) broken focal - conic fan texture during heating to isotropic liquid (I) and the reverse cooling process to crystalline solid (Cr) exhibit as Smectic - A phase.[H2L3] directly changed from crystal to isotropic at 294 ℃ and did not exhibit any mesophase texture and appear under (POM) as bright crystals, while the lanthanide(III) complexes are an enantiotropic liquid crystal exhibiting smectic - A (SmA) phases.[H2L4] exhibits smectic A (SmA) phases during heating to isotropic liquid (I) and the reverse cooling process to crystalline solid (Cr), However, its lanthanide(III) complexes didn’t exhibit any mesophase texture under (POM) or phase transition in (DSC) and directly changed from crystal to isotropic
