TY - DATA T1 - Magnetic and Luminescent Binuclear Double-Stranded Helicates PY - 2014/07/21 AU - Paula Cucos AU - Floriana Tuna AU - Lorenzo Sorace AU - Iulia Matei AU - Catalin Maxim AU - Sergiu Shova AU - Ruxandra Gheorghe AU - Andrea Caneschi AU - Mihaela Hillebrand AU - Marius Andruh UR - https://acs.figshare.com/articles/dataset/Magnetic_and_Luminescent_Binuclear_Double_Stranded_Helicates/2272807 DO - 10.1021/ic501051q.s003 L4 - https://ndownloader.figshare.com/files/3908824 KW - temperature dependence KW - 55 K KW - relaxation rate KW - Dynamic susceptibility measurements evidence KW - metal ions KW - helicate KW - Orbach mechanism KW - EPR spectroscopy KW - axis type anisotropy KW - dc field KW - Zn KW - fluorescence quantum yields KW - Co KW - exhibits fluorescence emission KW - tetrahedral geometry KW - M 2L KW - center KW - cobalt ions KW - helicand H 2L N2 - Three new binuclear helicates, [M2L2]·3DMF (M = Co­(II), 1, Zn­(II), 3) and [Cu2L2]·DMF·0.4H2O (2), have been assembled using the helicand H2L that results from the 2:1 condensation reaction between o-vanillin and 4,4′-diaminodiphenyl ether. The metal ions within the binuclear helicates are tetracoordinated with a distorted tetrahedral geometry. Direct current magnetic characterization and EPR spectroscopy of the Co­(II) derivative point to an easy axis type anisotropy for both Co­(II) centers, with a separation of at least 55 K between the two doublets. Dynamic susceptibility measurements evidence slow relaxation of the magnetization in an applied dc field. Since the distance between the cobalt ions is quite large (11.59 Å), this is attributed in a first instance to the intrinsic properties of each Co­(II) center (single-ion magnet behavior). However, the temperature dependence of the relaxation rate and the absence of slow dynamics in the Zn­(II)-doped sample suggest that neither the simple Orbach mechanism nor Raman or direct processes can account for the relaxation, and collective phenomena have to be invoked for the observed behavior. Finally, due to the rigidization of the two organic ligands upon coordination, the pure zinc derivative exhibits fluorescence emission in solution, which was analyzed in terms of fluorescence quantum yields and lifetimes. ER -