December 22, 2024
Mahmood Niad

Mahmood Niad

Academic Rank: Associate professor
Address:
Degree: Ph.D in chemistry
Phone: 07136333174
Faculty: Faculty of Nano and Biotechnology

Research

Title
Synthesis and characterization of sandwich-type polyoxometalates and investigation of their thermal behaviour
Type Thesis
Keywords
Sandwich-Type Polyoxometalates, Organic-Inorganic Hybrids, Conceptual DFT Descriptors, Porphyrins, Gaussian, AIM analysis, NBO analysis
Researchers Mahmood Niad (Primary advisor) , Khosro Mohammadi (Advisor)

Abstract

Part I: In this study, synthesis and characterization of sandwich-type polyoxometalate based organic-inorganic hybrids including Na12[Co4(PW9O34)2( PNA)2].10H2O and Na12[Co4(PW9O34)2(ABI)2].10H2O have been investigated. Since using each different organic ligand for the synthesis of polyoxometalate based organic-inorganic hybrids result in a unique structure, it seems crucial to find a unified synthesis procedure and propagate it to most of these ligands. For this purpose, substitution of water molecules by different organic ligands, such as 2-aminobenzimidazole and p-nitroaniline has been performed in aqueous solution in a closed teflon lined autoclave at 160˚C for 3 days. The obtained compounds have been characterized by ICP-MS, UV-Vis, FTIR, TGA-DSC and EDAX analysis. Using pyridine and imidazole have not yielded in desired product, so conceptual DFT descriptors of some organic ligands have been studied by B3LYP/6-311G(d,P) basis set and a model has been developed for prediction of synthesis of such hybrid compounds. The employed descriptors are consisted of global and local reactivity descriptors. According to the obtained results for global reactivity descriptors, organic ligands with least electronegativity, hardness, total electrophilicity and energy bond gap values and maximum total softness and chemical potential values, tend to substitute water molecules on the metal center, while other ligands prefer to react with peripheral sites of polyoxometalate component. Furthermore, based on the results for local reactivity descriptors, when positive component of fukui, local hardness and local softness are greater in value from their negative component, the reaction result in the desired product. In addition, ligands with dipole moments greater than of water and larger in size are most favorite ligands for this reaction. The aforementioned model has been showed graphically in below scheme. Based on the mentioned method, 5-nitrobenzimidazole, 4-nitroaniline, 2-amino