Nanoporous Magnets of Chiral and Racemic [{Mn(HL)}₂Mn{Mo(CN)₇}₂] with Switchable Ordering Temperatures (T_C = 85 K ↔ 106 K) Driven by H₂O Sorption (L = N,N-Dimethylalaninol)

Abstract

Molecule-based solids represent a rare opportunity to combine, adjust, and interrelate structural and physical functionalities to develop multifunctional materials. Here we report on a series of porous supramolecular magnets whose magnetic properties are related to their sorption state. A family of magnets of the formula [{Mn(HL)(H2O)}2Mn{Mo(CN)7}2].2H2O have been obtained by assembling the heptacyano-metalate building unit {Mo(CN)7}4- with Mn(II) in the presence of protonated N,N-dimethylalaninol (L) as ligand, the latter being either as a racemic mixture or as a chiral R- or S-enantiomer. The resulting magnets possess an open framework structure and exhibit a TC with a switching behavior (TC = 85 K <--> 106 K) as a function of the hydration state. Moreover, chiral magnets are formed with the optically active ligands. The H2O and gas (N2, CO2, CO) sorption features, the magnetic behavior of both the hydrated and dehydrated magnets, and the crystal structures of the hydrated chiral (S) and racemic magnets are described.

Iron(II)-octacyanoniobate(IV) ferromagnet with TC 43 K

“…The energy has been calibrated to the spectra of the reference sample, measured simultaneously with the sample. XANES spectra of both samples, K 4 [Nb(CN) 8 ]·2H 2 O and 1, at the Nb:K edge, have the same edge energy, shifted to 6.6(1) eV and 16.8(5) eV, taken as the first and second maximum of the first derivative and 12.8(1) eV taken as the half of the edge jump, corresponding to the metallic Nb foil (0.0(1) eV, 12.5(1) eV and 5.7(1) eV, respectively). The shape of both lines is also identical in the XANES energy range.…”

“…10- 16 We have introduced the inorganic-organic hybrid octacyanoniobate(IV)-based networks offering relatively high T c (up to 62 K) together with the opportunity of its tuning on the molecular level. [17][18][19] Parallel to our research, Ohkoshi and co-workers initiated research on the iron(II) SCO (spin-crossover) in Fe II -[Nb IV (CN) 8 (LT phase) between 325-150 K, the latter providing the ferrimagnetically ordered phase below T c = 12 K. Incorporation of the 3-py-CH 2 OH ligand reduces the number of coordination sites at the Fe centre available for cyano-bridging and thus reduces the overall cyano-connectivity, resulting in the T c value lying far beyond the reach of spin-crossover phenomena. molecules, while the second one is dominated by the loss of CNions.…”

Cu(II) and Zn(II) Complexes with an N- and O-Donor Ligand: Structural Characterization, Jahn-Teller Effect and Fluorescence

“…Metal ions possessing unpaired electrons, such as Mn(II), Co(II), Ni(II), and Cu(II) etc. could be bridged by ligands to form polynuclear subunits which may mediate magnetic interactions [11,12]. Moreover, complexes containing metal centers with d 10 electron configuration, such as Zn (II) and Cd(II), may exhibit luminescence [13,14].…”

Synthesis, Structure and Physical Properties of A Novel 2D Cd(II) Coordination Polymer Involving 4-Thiopyridine Based on in situ Formation from 4,4'-Dithiodipyridine

“…[1][2][3][4][5][6] It is well known that the organic ligand is the key factor that influences the construction of coordination polymer. Recently, the in situ ligand synthesis as a new approach to prepare coordination polymers are of great interest.…”