General Papers ARKIVOC 2008 (xiv) 158-165
Synthesis and characterisation of several di-, tri-, and tetra- radicals linked by flexible or rigid linkers
Miron T. Caproiu,a Gabriela Ionita,b Constantin Draghici,a and Petre Ionita*b
aCenter of Organic Chemistry, Spl. Independente 202B, Bucharest 71141, Romania bInstitute of Physical-Chemistry, 202 Spl. Independentei, Bucharest 060021, Romania E-mail:
[email protected]
Abstract
This paper reports the synthesis of eight new polyradicals (di-, tri-, and tetra- stable radicals) linked by flexible (aliphatic) or rigid (aromatic) units. Their preparation, as well as their electron paramagnetic resonance characteristics are described and discussed. These polyradicals were successfully tested as spin-labels for gold nanoparticles.
Keywords: ESR, stable radical, polyradicals, synthesis, gold nanoparticles
Introduction
Polyradicals are compounds of special interest, due to their (para)magnetic properties, as well as their potential probes and sensors in many physical, chemical, or biological processes, or in materials labelling (like nanoparticles, silica, polymers, etc).1-4
Organic-based magnetic materials are an attractive field in materials chemistry, which offers the possibility to build step-by-step single molecules which contain many stable radical moieties, of the same type or of different types.5-8 Co-operative magnetic properties may led to the formation of an organo-metallic solid, with important practical properties; moreover, the properties of these compounds may be tuned by using the appropriate building blocks to get it right.9-11
Pure organic materials based on stable polyradicals (stable organic high spin molecules) are shown in literature data, and they exhibit many interesting features, like ferro- or ferric magnetism, molecular magnets or wires, switches, and other metallic properties.5-11
Our interest 12 in preparation of new paramagnetic (multispin) compounds prompted us to synthesise several stable di-, tri-, and tetra-radicals, in which the paramagnetic moieties are separated by flexible or rigid linkers. Due to their constituency, these polyradicals may be involved in several types of processes, like acid-base or redox, or to label gold nanoparticles.4-6 T
There is also an interest in measuring and in the correlation of the distances between spins
ISSN 1551-7012 Page 158 ©ARKAT USA, Inc.
