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Crystal engineering of homometallic FeIII and heterometallic FeIII/4 f carboxylate clusters and coordination polymers: synthesis, characterization, and properties


Author: Botezat Olga
Degree:doctor of chemistry
Speciality: 02.00.05 - Electrochemistry
Year:2019
Scientific adviser: Victor Kravtov
doctor, associate professor (docent), Institute of Applied Physics of the ASM
Scientific consultant: Svetlana Baca
doctor, associate professor (docent)
Institution: Institute of Applied Physics of the ASM

Status

Term of presenting of the thesis 27 March, 2019

Abstract

Adobe PDF document2.19 Mb / in romanian
Adobe PDF document2.29 Mb / in english

Thesis

CZU 546.72-32:548.5(043.2) 546.650-32:548.5(043.2)

Adobe PDF document 9.67 Mb / in english
176 pages


Keywords

crystal engineering, iron, lanthanides, carboxylates, clusters, coordination polymers, magnetism

Summary

PhD thesis in chemistry, speciality 144.07 – solid state chemistry. Chisinau, 2019. The thesis consists of introduction, 4 chapters, general conclusions and recommendations, bibliography of 259 titles, 113 pages of the basic text, 8 tables, 50 figures, 4 annexes. The obtained results were published in 21 scientific papers: 7 articles and 14 theses at conferences.

Field of study: natural sciences.

The goal and objectives of the thesis: the construction of new homo- and heterometallic FeIII/FeIII-4f carboxylate magnetic clusters and coordination polymers based on them using crystal engineering principles. To achieve this goal the following objectives were set: development of synthetic approaches for the preparation of FeIII/FeIII-4f coordination clusters with variable nuclearity and topology and cluster-based coordination polymers; synthesis of new crystalline designed compounds; determination of their structures using a single crystal X-ray diffraction analysis; characterization of their physico-chemical properties; investigation of their magnetic properties b y variable temperature susceptibility measurements. Scientific novelty and originality: consists in the elaboration of methods and conditions of syntheses, including hydro(solvo)thermal, microwave and ultrasonic treatment, that resulted in 42 new FeIII/FeIII-4f compounds. For the first time, a series of the largest wheel-shaped heterometallic {Fe18Ln6}-type clusters has been obtained. The influence of the nature of metals and ligands on the composition, structure, and magnetic properties of Fe/Fe-Ln compounds has been determined.

Scientific problem solved. The optimal synthetic conditions for the obtaining of Fe III/FeIII-4f carboxylate clusters with enhanced magnetic properties and coordination polymers of Fe III (0D, 1D and 3D) with notable porosity, using FeIII oxo-carboxylate precursors and N,O-donor ligands have been established. The prepared heterometallic {Fe4Dy2}, {Fe6Dy3}, {Fe6Dy4}, {Fe6Tb4}, {Fe7Dy4}, {Fe18Dy6}, and {Fe18Tb6}-type clusters showed a magnet-like behavior.

The theoretical significance. The thesis contributes to the elaboration of effective strategies for obtaining new materials based on coordination compounds of Fe III and LnIII metals with magnetic properties. Experimental results of structural, spectroscopic, and magnetic measurements extended the knowledge of this class of compounds and provided novel insights in the fundamental understanding of the principles that govern magnetic behavior in the discrete clusters and clusterbased structures. The applied value of the work consists in the fact that new synthesized d/d- f compounds can be used as prospective materials for developing of magnetic sensors and memory devices.

Implementation of scientific results. The structural and magnetic data of the obtained polynuclear clusters have been used for the development of the wxJFinder program to calculate the Heisenberg coupling constants J in FeIII(μ2+n-O)FeIII systems.

Summary


1. CURRENT STATE OF RESEARCH IN THE FIELD OF HOMO- AND HETEROMETALLIC FeIII-LnIII POLYNUCLEAR CARBOXYLATES
  • 1.1. Crystal engineering: brief introduction
  • 1.2. Homometallic FeIII carboxylate clusters and cluster-based coordinat ion polymers
  • 1.3. Heterometallic FeIII-LnIII carboxylate clusters
  • 1.4. Conclusions to the Chapter 1

2. EXPERIMENTAL METHODS OF SYNTHESIS, ANALYSIS AND INVESTIGATIONS
  • 2.1. Materials, general methods of investigation and synthetic strategies
  • 2.2. Synthesis of homometallic FeIII clusters
  • 2.3. Synthesis of homometallic FeIII carboxylate coordination polymers
  • 2.4. Synthesis of heterometallic FeIII-LnIII carboxylate wheels
  • 2.5. Synthesis of heterometallic FeIII-LnIII carboxylate clusters
  • 2.6. Conclusions to the Chapter 2

3. HOMOMETALLIC POLYNUCLEAR FeIII CLUSTERS AND COORDINATION POLYMERS
  • 3.1. Di-, tri-, tetra, hexa-, hepta-, octa-, dodeca-, docosanuclear FeIII clusters with N,O-donor ligands
  • 3.2. Homometallic FeIII carboxylate coordination polymers with N-bridging ligands
  • 3.3. Conclusions to the Chapter 3

4. HETEROMETALLIC POLYNUCLEAR FeIII-LnIII CARBOXYLATE COMPOUNDS
  • 4.1. Nona-, deca-, tetracosanuclear FeIII-LnIII carboxylate wheels
  • 4.2. Hexa- and undecanuclear FeIII-LnIII carboxylate clusters
  • 4.3. Conclusions to the Chapter 4

OVERALL CONCLUSIONS AND RECOMMENDATIONS
REFERENCES