Search In this Thesis
   Search In this Thesis  
العنوان
Synthesis, characterization, molecular
modeling and applications on complexes of
some azine derivatives /
المؤلف
Teleb,Hany Magdy Ahmed.
هيئة الاعداد
باحث / Hany Magdy Ahmed Teleb
مشرف / Ali Mahmoud Taha
مشرف / Magdy Shebl Saleh
مشرف / Omima Mohamed Ibrahim
تاريخ النشر
2018
عدد الصفحات
247p.:
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
Inorganic Chemistry
تاريخ الإجازة
1/1/2018
مكان الإجازة
جامعة عين شمس - كلية التربية - الكيمياء
الفهرس
Only 14 pages are availabe for public view

from 247

from 247

Abstract

In the present work, 12 organic ligands and twelve complexes,were synthesized. Structures of the ligands and complexes have been deduced from elemental analyses and spectral data (IR, 1HNMR, XRD and electronic spectra), as well as magnetic moment, thermal analysis and molar conductance measurments. The ligands, were prepared by a condensation of 5,6-diphenyl-[1,2,4]-triazin-3-ylhydrazine (DHT) with respective aldehyde or ketone in molar ratio 1:1 to yeild the corresponding hdrazone ligand.
230
The dissociation and formation constants of some ligands and complexes, have been investigated in 75% (v/v) dioxane-water at different temperatures. The corresponding thermodynamic parameters were evaluated. The results obtained reveals that the ligand behaves as monobasic forming 1:1 and 1:2 M:L molar ratio in solution. logK1 logK2, indicating that, the vacant orbits of the metal ions are more freely available for binding of the first ligand molecule than the second one. Finally, the stability of the formed complexes affected by: HSAB properties, the size of chelate ring and temperature consisting with the exothermic of complexation.
The polarographic reduction of HBDHT, o-HBDHT and HBzDHT were studied reveals that the polarograms of these compounds exhibited two waves at pH˂7 and one wave at pH˃7, except HBzDHT that shows one polarographic wave at all pH range. The height of the two waves remain approximately in the range of pH studied .whereas the half –wave potential is pH dependent. Polarographic reduction of the current compounds are irreversible and diffusion controlled. The azomethane or hydrazo group is reduced in the protonated form to produce, R-NH-NH2 and RCH3, where R- = 3 substituted -5,6-diphenyl-1,2,4-triazine and R= C6H5 or o-OH-C6H5.
The solid complexes, were obtained by reacting of some of the current ligands (HBDHT and o-HBDHT) with different metal ions (Co(II), Ni(II), Cu(II), Fe(III), Zn(II) and UO2(II) )- as nitrates, or acetates with molar ratio (1:1) in ethanol medium. The formed solid complexes are mononuclear ML except Co(II) which forms ML2 complexes
The current ligands showed a variety of bonding modes toward the metal ions. HBDHT ligand, behaves as monoanionic and NN bidentate in all complexes via C=N of azomethine and triazine ring. However, o-HBDHT ligand, acts as monoanionic NNO tridentate in all complexes except Co(II)complexes it behaves as NO bidentate.
231
The formed complexes display octahedral geometry except Cu(II)- and Zn(II)-complexes, they are, square planar and tetrahedral geometries, respectively.
Molecular orbital calculations were carried out on the free ligands and their solid complexes using Gaussian 09 program on DFT method at B3LYP level. The calculated structural parameters data were correlated with some of the experimental data such as UV-VIS, IR and fluorescence spectra. Investigation of the structural parameters data and their correlations refers the following points.
1. The calculated heat of formation (ΔHf) as well as total energy, dipole moment,Ehomo,Elumo and Egap of the free ligands conformers, predicted the more favorable tautomeric forms of the ligands.
2. ΔEgap of all complexes are smaller than that of their free ligands, indicates that the reactivity of complexes are higher than free ligands.
3. Generally, bond lengths of coordinating centers are longer than the corresponding in the free ligands (N-N & C=N) triazine and C=N azomethine).
4. The increasing of ΔEgap leads to blue shift and decreases of frequency of (C-O) bond i.e. strong coordinating between oxygen and metal ion.
- Applications of HBDHT and o-HBDHT ligands and some of their metal complexes in various fields have included: fluorescence, optoelectronic and biological submissions.
-All the synthesized ligands and their complexes may attend as potential photoactive provisions as indicated from their distinctive fluorescence. This new approach allows for the extraction of some new information not obtained from excitation and/or fluorescence spectroscopy for a single spectral scan. The HBDHT compound has the maximum probability of fluorescence emission, as it has the highest ɛ value (10.2 x106). However, DHT and its hydrazone, DHBDHT have the minimum probability of
232
fluorescence emission, ɛ value (2.1 x106). In contrast, the lifetime go in the opposite direction. The Stokes-shifted emission spectra were measured for various photoactive molecules in solution, varies in the range 51 - 290 nm. The lowest. Stokes shift found for DHBDHT (51 nm), whereas the highest Stokes shift found for p-HBDHT (290 nm). The complexes of o-HBDHT have higher stokes shift than those of HBDHT. This promising optical properties of o-HBDHT- complexes will be good candidates in the solar cell devices. The quantum yield values are found in the range 0.12 – 0.62, indicate that the lowest quantum yield is p-MBDHT (φ = 0.12). However, the brightest fluorophore is the vaniline compound (φ = 0.62), it is known that the higher quantum yield is desirable in most imaging applications.
- The optical characteristics of the prepared films were studied using spectrophotometric measurements in a wide spectral range of 200-2500 nm. Some important optical parameters such as extinction index, refractive index, dispersion energy, oscillator energy and high-frequency dielectric constant were extracted. Analysis of the absorption coefficient near the fundamental absorption edge confirms an indirectly allowed transition with the energy gaps of 1.7, 2.55 and 3.80 eVfor o-HBDHT, Ni-o-HBDHT and Cu-BDHT, respectively. The dispersion of the refractive index was analyzed in terms of single oscillator model expressed by Wemple–Didomenico. The heterojunction of o-HBDHT, Cu-BDHT and Ni-o-BDHT films/p-Si showed remarkable rectifying behavior in dark as well as demonstrated distinguished photovoltaic characteristics under illumination of 100 mW/cm2. Furthermore, the time-dependent photocurrent investigation demonstrated an acceptable response time to the influence of light. This responsivity characteristic specifies a recommendation for the prepared heterojunction for opening another point of view in photodetector applications.
-Antimicrobial activity of the ligands and their metal complexes was examined against selected kinds of bacteria, yeast and fungi and showed low bioactivity.