Tripods of general formula R’–O–CH2C(CH2OH)3 are excellent site-specific ligands for the preparation offunctionalized Fe4 single-molecule magnets. Herein, we describe the synthesis and characterization oftwo novel complexes designed to bind graphene surfaces, in which the R group consists of an alkyl spacer–(CH2)n– (n = 6 and 10) and a terminal pyrenyl moiety. The site-specific ligand substitution on [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane) with the new tripods has been studied with 2H NMR on isotopically-enriched samples, revealing that, once formed, these clusters are stable in solution over longtimescales. It was not possible to isolate the new compounds as crystalline solids, nevertheless they werechemically characterized by elemental analysis and 1H NMR. The presence of the pyrenyl ending groupsprompted us to investigate the effect of metal complexation on fluorescence, and a full pyrene-to-ironcluster excitation energy transfer was observed. The analysis of the magnetic behaviour revealed anS = 5 ground spin state with a negative zero-field splitting parameter D = 0.42 cm1.
A novel class of tetrairon(III) single-molecule magnets with graphene-binding groups / Danieli, Chiara; Cornia, Andrea; C., Cecchelli; R., Sessoli; A. L., Barra; Ponterini, Glauco; Zanfrognini, Barbara. - In: POLYHEDRON. - ISSN 0277-5387. - STAMPA. - 28:9-10(2009), pp. 2029-2035. [10.1016/j.poly.2008.12.024]
A novel class of tetrairon(III) single-molecule magnets with graphene-binding groups
DANIELI, Chiara;CORNIA, Andrea;PONTERINI, Glauco;ZANFROGNINI, Barbara
2009
Abstract
Tripods of general formula R’–O–CH2C(CH2OH)3 are excellent site-specific ligands for the preparation offunctionalized Fe4 single-molecule magnets. Herein, we describe the synthesis and characterization oftwo novel complexes designed to bind graphene surfaces, in which the R group consists of an alkyl spacer–(CH2)n– (n = 6 and 10) and a terminal pyrenyl moiety. The site-specific ligand substitution on [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane) with the new tripods has been studied with 2H NMR on isotopically-enriched samples, revealing that, once formed, these clusters are stable in solution over longtimescales. It was not possible to isolate the new compounds as crystalline solids, nevertheless they werechemically characterized by elemental analysis and 1H NMR. The presence of the pyrenyl ending groupsprompted us to investigate the effect of metal complexation on fluorescence, and a full pyrene-to-ironcluster excitation energy transfer was observed. The analysis of the magnetic behaviour revealed anS = 5 ground spin state with a negative zero-field splitting parameter D = 0.42 cm1.
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