Dalton Transactions

doi: 10.1039/c1dt90144cpmid: N/A

doi: 10.1039/c1dt90145apmid: N/A

doi: 10.1039/c1dt90146jpmid: N/A

Guo, Yun-Nan; Xu, Gong-Feng; Guo, Yang; Tang, Jinkui

doi: 10.1039/c1dt10474hpmid: 21829790

Over the past decade, lanthanide compounds have become of increasing interest in the field of Single Molecule Magnets (SMMs) due to the large inherent anisotropy of the metal ions. Heavy lanthanide metal systems, in particular those containing the dysprosium(iii) ion, have been extensively employed to direct the formation of a series of SMMs. Although remarkable progress is being made regarding the synthesis and characterization of lanthanide-based SMMs, the understanding and control of the relaxation dynamics of strongly anisotropic systems represents a formidable challenge, since the dynamic behaviour of lanthanide-based SMMs is significantly more complex than that of transition metal systems. This perspective paper describes illustrative examples of pure dysprosium(iii)-based SMMs, published during the past three years, showing new and fascinating phenomena in terms of magnetic relaxation, aiming at shedding light on the features relevant to modulating relaxation dynamics of polynuclear lanthanide SMMs.

Meng, Xing; Qin, Chao; Wang, Xin-Long; Su, Zhong-Min; Li, Bo; Yang, Qi-Hua

doi: 10.1039/c1dt11227apmid: 21904746

Immobilization of the chiral salen-metal complex [MnIII(salen)(H2O)2ClO4] on the Keggin-type polyoxometalate (POM) skeletons leads to the isolation of POM derivatives functionalized with chiral salen-metal complexes, which represent the first examples of introducing chiral salen-metal complexes into the POM systems.

Kauf, Thomas; Braunstein, Pierre

doi: 10.1039/c1dt10804bpmid: 21713291

The reaction of TCNE and TCNQ zwitterionic benzoquinonemonoimine derivatives under basic conditions resulted in HCN elimination to give a tricyanoethenyl derivative – which forms a π-complex with Pd(0) – or a stable malodinitrile salt, respectively. In the latter case, chemoselective C-alkylation was observed whereas oxidation led to dimerization by C–C coupling.

Höppe, Henning A.; Kazmierczak, Karolina; Kacprzak, Sylwia; Schellenberg, Inga; Pöttgen, Rainer

doi: 10.1039/c1dt10043bpmid: 21655577

The optical emission properties of the lanthanoid catena-polyphosphates Ln(PO3)3 (Ln = Y, Gd, Lu) doped with europium were investigated. Incommensurately modulated β-Y(PO3)3 : Eu (super space group Cc (0|0.364|0)0) and Gd(PO3)3 : Eu (space group I2/a) show the usual emission characteristics of Eu3+, while in Lu(PO3)3 : Eu (space group Cc) the europium is unprecedentedly partially reduced to the divalent state, as proven by both a broad emission band at 406 nm excited at 279 nm and an EPR spectroscopic investigation. 151Eu-Mössbauer spectroscopy showed that only a very small part of the europium is reduced in Lu(PO3)3 : Eu. An explanation for this unusual behaviour is given.

Delahaye, Emilie; Xie, Zailai; Schaefer, Andreas; Douce, Laurent; Rogez, Guillaume; Rabu, Pierre; Günter, Christina; Gutmann, Jochen S.; Taubert, Andreas

doi: 10.1039/c1dt10841gpmid: 21881660

Yu, Byong Yong; Kwak, Seung-Yeop

doi: 10.1039/c1dt10650cpmid: 21904731

Based on a self-assembly strategy, spherical mesoporous cobalt and nickel ferrite nanocrystal clusters with a large surface area and narrow size distribution were successfully synthesized for the first time via a template-free solvothermal process in ethylene glycol and subsequent heat treatment. In this work, the mesopores in the ferrite clusters were derived mainly from interior voids between aggregated primary nanoparticles (with crystallite size of less than 7 nm) and disordered particle packing domains. The concentration of sodium acetate is shown herein to play a crucial role in the formation of mesoporous ferrite spherical clusters. These ferrite clusters were characterized in detail using wide-angle X-ray diffraction, thermogravimetric-differential thermal analysis, 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, and other techniques. The results confirmed the formation of both pure-phase ferrite clusters with highly crystalline spinel structure, uniform size (about 160 nm) and spherical morphology, and worm-like mesopore structures. The BET specific surface areas and mean pore sizes of the mesoporous Co and Ni-ferrite clusters were as high as 160 m2 g−1 and 182 m2 g−1, and 7.91 nm and 6.87 nm, respectively. A model for the formation of the spherical clusters in our system is proposed on the basis of the results. The magnetic properties of both samples were investigated at 300 K, and it was found that these materials are superparamagnetic.

Inglis, Ross; Houton, Edel; Liu, Junjie; Prescimone, Alessandro; Cano, Joan; Piligkos, Stergios; Hill, Stephen; Jones, Leigh F.; Brechin, Euan K.

doi: 10.1039/c1dt11118cpmid: 21858345

The serendipitous self-assembly of the complex [MnIII2ZnII2(Ph-sao)2(Ph-saoH)4(hmp)2] (1),whose magnetic core consists solely of two symmetry equivalent Mn(iii) ions linked by two symmetry equivalent –N–O– moieties, provides a relatively simple model complex with which to study the magneto-structural relationship in oxime-bridged Mn(iii) cluster compounds. Dc magnetic susceptibility measurements reveal ferromagnetic (J = +2.2 cm−1) exchange resulting in an S = 4 ground state. Magnetisation measurements performed at low temperatures and high fields reveal the presence of significant anisotropy, with ac measurements confirming slow relaxation of the magnetisation and Single-Molecule Magnetism behaviour. Simulations of high field, high frequency EPR data reveal a single ion anisotropy, D(MnIII) = −3.83 cm−1. DFT studies on a simplified model complex of 1 reveal a pronounced dependence of the exchange coupling on the relative twisting of the oxime moiety with respect to the metal ion positions, as suggested previously in more complicated [MnIII3] and [MnIII6] clusters.