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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - SPINSWITCH (Multifunctional Spin Crossover Materials)

Teaser

Summary

Molecular multifunctional switching materials attractive both scientificaly and technologicaly due to potential utilization in molecular electronics including switches, information storage, signal processing, molecular spintronics, and sensors. A great advantage of molecule-based bistability is the great variety of external stimuli for change of electronic geometrical states of individual molecules. Spin crossover (SCO) materials are a type of molecular functional material possessing labile electronic configurations switchable between the high- (HS) and low-spin (LS) states in response to temperature, pressure, light, substrates, phase transition and is mostly studied for iron(II) complexes. In the HS and LS states SCO compounds reveal great differences in magnetism, optical and dielectric properties, colour and structure.
The field of SCO researches is extremely actively developing during last 20 years toward materials of technological interest. Among prominent highlights of SCO research are contrast agents for tomography, thermal displays, dielectric bistability for information storages, photo-commutation of spin state, microactuators.
The current SCO investigations are guided toward the construction of addressable molecular systems, where (i) SCO is controlled by another easily controllable function (sorption-absorption, phase behaviour etc.) and/or (ii) SCO controls another useful property (mechanical, electrical, optical, fluorescence, etc.). An interesting aspect is the use of SCO units as building blocks for the construction of sensing materials capable of acting as switches in response to change in ambient conditions (pressure, temperature, humidity, chemical contaminants etc.) due to the predesigned structure of the molecules, where the periphery of the molecule functions as a receiver for the external stimuli and becomes an essential element of the multifunctional SCO complex. This type of sensitivity opens a way toward the precise control of the SCO parameters (temperature, abruptness, completeness), a task elusive for tackling by other methods.
SPINSWITCH has several main goals:
-Investigation of new multifinctional materials, composites, hybrid mixtures where a controlable macroscopic event controls SCO properties;
-New metal-organic SCO Hofmann clathrates with sorption-desorption functionlity;
-Pressure effect study for prototyping pressure sensors;
-Nanostrucuturation of SCO materials;

Work performed

- Desing and synthesis of new ligands suitable for preparation of multifunctional SCO compounds, new SCO compounds and nanomaterials (nanoparticles and thin films) based on them. Synthetic protocols for new SCO complexes with pyridazines, naphtyridine, isothiocarbohydrazide were developed. Protocols towards complexes with isomerizable ligands and those carrying long alkyl chains are elaborated. We have synthesized new SCO Fe(II) cyanometallic and triazolic nanoparticles and films. Films based upon an Fe(II) triazolylborate complex were elaborated.
- Full physico-chemical characterization of new compounds and nanomaterials. We obtained physicochemical parameters for new SCO complexes with pyridazines, naphtyridine, isothiocarbohydrazide, series of complexes with isomerizable ligands and those carrying long alkyl chains, new SCO cyanometallic, triazolic and triazolylborate nanoparticles and film..
- Pressure measurements of SCO compounds, elaboration of SCO pressure sensors. We obtained data for SCOfor the nanoparticles of iron-gold complex under pressure. Pressure effects for Fe(II) triazolic nanoparticles and 2 polymorphs of one Fe(III) SCO complex were studied. Pressure effects on the electrical properties of bulk and nano samples of iron-gold complex were monitored. Effects of pressure on the Fe(II) triazolic nanoparticles aqnd electric properties of SCO thin films were investigated.

Final results

The proposed project expands the border between chemistry, physics and nanoscience. The development of techniques, strategies, and approaches within these areas is continuous. To maintain a tight contact and collaboration between all the activity participants (countries, agencies, research groups) that operate in the frontiers of these fields is a priority for ERA in order to sustain and potentiate the strength and attractiveness of its research environment. We believe that this project moves in this direction and encourages the exchange of research expertise, know-how, and technologies to create the background for the further innovation activity. The success of this exchange program will be the result of a tight collaboration on research and technological development among all seven participants and will contribute directly in the application of high-added value integrated approaches, combining synthetic organic and coordination chemistry, magnetochemistry, photophysics and nanotechnology and providing a general strategy for systematic design of novel materials of technological use with predefined properties that will allow development of new multifunctional SCO materials, efficient, selective and low-cost chemical detectors and pressure sensors.
New multifunctional compounds are of particular interest for academic and industrial partners working in the growing field of molecular materials. These materials can find application in a new generation of molecule-based devices. We have developed compounds with unique characteristics of spin crossover and achieved extraordinary effects of the pressure on different SCO materials. Until the end of the project we plan to extand the set of nes SCO materials for potential application and to propose a SCO pressure sensor.