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Influence of the ligand shell on the surface orientation of Mn12 single molecule magnets

2009; Elsevier BV; Volume: 28; Issue: 9-10 Linguagem: Inglês

10.1016/j.poly.2008.11.028

1873-3719

M. Fonin, S. Voss, Simon J. Herr, G. de Loubens, A. D. Kent, M. Burgert, Ulrich Groth, U. Rüdiger,

Porphyrin and Phthalocyanine Chemistry

Si ngle molecule magnetsMn "Here we repo rt the synthesis, investigatiol1 as weil as surface deposition of a truly axial symmetry Mn l2 diphenylphosphinate (Mn' 2-phn ) single moleeule magnet.Out 0116 acetate ligands encapsulating t.he Mn J20' 2 core.12 ligand s were exchanged by diphenylphosphinate in this compound.Mn ,rphn shows well-deflned magnetic 11ysteresis curves indicating .I very high crystal quality.A monolayer 01 Mn, r phn was chemi cally gralted on a lunctionalized Au( 1 1 1) surface via ligand exchange reaction and stud ied by mcans of scannin g tunneling mic rosco py and spectroscopy.Via distance-voltagc spectroscopy we dcte rmine th e real-space height of the Mn 12-phn molecules with high accura.cy.A large spread in the measured molecular heights obtained from the distance-voltage spectra lI1dicates the absence of prefer ential orientation of Mn ",-phn molecules with respec.t to the surface which we attribute to the equal anchoring probability of all diphenylphosphinate ligands in Mn,rphn while none of the four acetate ligands are cxchanged.These results are compared with the experimental data obtained from a d ifferent Mn' 2 derivative contai ning 16 thiophe necarboxylatc ligands.In general.we show that the substitution of the ligand shell may have a major impact on th e surface orientation ofthe MnJ2 clusters deposited on Au. i.e. on the orientatiol1 of the easy magnetization axis.