The project targets at efficient and progressive design of novel and advanced functional materials based on metal-organic complexes. Combination of metal centres with polydentate organic ligands provide colossal, structurally-diverse, platforms possessing a variety of magnetic, electrical, thermal, optical and other properties. In the proposed project, two analogue bridging ligands, oxalate (C2O42−) and substituted 2,5-dihydroxyquinonate (DHQ), will be used in the preparation of the coordination polymers of different dimensionality and topology. Their interactions with transition metal cations involve a variety of magnetic phenomena, which can be tuned by highly sensitive selection of structural fragments.

The oxalate-based complexes will be studied not only as potential magnetic materials ordering at a certain temperature, but also as the single-source precursors for the preparation of technologically important mixed-metal oxides through the thermal decomposition process. This method of preparing oxides, as compared to conventional solid-state reactions, has several advantages: shorter thermal treatment at lower temperature, without repeating grinding procedures, and the products are more homogeneous.

The DHQ complexes will be studied due to their potential for charge transfer, which may lead to materials with reversible magnetic transition. Also, promising class of the ligands are stable semiquinone radicals derived from variously substituted DHQs. So far, their complexes with transition metals are little-known and have not been exploited for design of functional materials. The interdisciplinary nature of the project requires a variety of methods to characterise these advanced materials: single-crystal and powder X-ray diffractions including X-ray charge density studies, thermal analyses (TG/DTA), IR, UV/Vis and EPR spectroscopies, etc. The results obtained will be used to correlate their structure and properties.

The three main direction of this project are :

1. Preparation and characterization of novel coordination polymers of transition metals with oxalate and 2,5-DHQ ligands with fine-tuned magnetic properties.
2. Study of heterpolynuclear oxalate complexes as the single-source precursors for the preparation of the mixed-metal oxides through their thermal decomposition; detailed characterization of the obtained phases and evaluation of their physical properties, such as structural, thermal, optical, magnetic, electric, photocatalytic, etc.
3. Preparation and study of complexes of transition metals with semiquinone radicals as ligands: development of synthetic methods and detailed studies of their properties and stability. An evaluation of their physical properties in view of their potential as (multi)functional materials.

Project Results

Available on the Croatian scientific bibliography web pages.