title: Progressive Transformation between Two Magnetic Ground States for One Crystal Structure of a Chiral Molecular Magnet.
abstract: We report the exceptional observation of two different magnetic ground states (MGS), spin glass (SG, T(B) = 7 K) and ferrimagnet (FI, T(C) = 18 K), for one crystal structure of [{Mn(II)(D/L-NH2ala)}3{Mn(III)(CN)6}]·3H2O obtained from [Mn(CN)6](3-) and D/L-aminoalanine, in contrast to one MGS for [{Mn(II)(L-NH2ala)}3{Cr(III)(CN)6}]·3H2O. They consist of three Mn(NH2ala) helical chains bridged by M(III)(CN)6 to give the framework with disordered water molecules in channels and between the M(III)(CN)6. Both MGS are characterized by a negative Weiss constant, bifurcation in ZFC-FC magnetizations, blocking of the moments, both components of the ac susceptibilities, and hysteresis. They differ in the critical temperatures, absolute magnetization for 5 Oe FC (lack of spontaneous magnetization for the SG), and the shapes of the hysteresis and coercive fields. While isotropic pressure increases both T(crit) and the magnetizations linearly and reversibly in each case, dehydration progressively transforms the FI into the SG as followed by concerted in situ magnetic measurements and single-crystal diffraction. The relative strengths of the two moderate Mn(III)-CN-Mn(II) antiferromagnetic (J1 and J2), the weak Mn(II)-OCO-Mn(II) (J3), and Dzyaloshinkii-Moriya antisymmetric (DM) interactions generate the two sets of characters. Examination of the bond lengths and angles for several crystals and their corresponding magnetic properties reveals a correlation between the distortion of Mn(III)(CN)6 and the MGS. SG is favored by higher magnetic anisotropy by less distorted Mn(III)(CN)6 in good accordance with the Mn-Cr system. This conclusion is also born out of the magnetization measurements on orientated single crystals with fields parallel and perpendicular to the unique c axis of the hexagonal space group.
authors.affiliation: Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.|Institute for Advanced Materials Research, Hiroshima University & Natural Science Center for Basic Research and Development , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.|Center for Chiral Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Sadafumi
authors.initials: S
authors.lastname: Nishihara
authors.affiliation: Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.|Institute for Advanced Materials Research, Hiroshima University & Natural Science Center for Basic Research and Development , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.|Center for Chiral Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Center for Chiral Science, Hiroshima University , 1-3-1, Kagamiyama, Higashi Hiroshima, Hiroshima 739-8526, Japan.|Institut de Chimie de Strasbourg, Université de Strasbourg , CNRS-UMR 7177, 4 rue Blaise Pascal, 67008 Strasbourg Cedex, France.
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo