TY - JOUR
T1 - Single-chain magnet behavior in an alternated one-dimensional assembly of a MnIII schiff-base complex and a TCNQ radical
AU - Miyasaka, Hitoshi
AU - Madanbashi, Tomokura
AU - Sugimoto, Kunihisa
AU - Nakazawa, Yasuhiro
AU - Wernsdorfer, Wolfgang
AU - Sugiura, Ken Ichi
AU - Yamashita, Masahiro
AU - Coulon, Claude
AU - Clérac, Rodolphe
PY - 2006/9/18
Y1 - 2006/9/18
N2 - An alternated 1:1 chain compound of a MnIII salen derivative and the TCNQ monoradical was synthesized: [Mn(5-TMAMsaltmen)-(TCNQ)](ClO 4)2 (1) (TCNQ = tetracyano-p-quinodimethane; 5-TMAM-saltmen = N,N′-(1,1,2,2-tetramethylethylene) bis(5-trimethylammoniomethylsalicylideneiminato)). Compound 1 has a zigzag chain structure packed with adjacent chains with an interchain Mn⋯Mn distance of over 8 Å. As compound 1 contains no crystallization solvent, the void spaces between chains are occupied only by ClO4- counter ions. Compound 1 has a structure reminiscent of what has been observed in the family, of MnIII(porphyrin)-TCNE or -TCNQ compounds reported previously by Miller and co-workers and we demonstrate herein its unique single-chain magnet behavior among this family of compounds. The direct current (dc) magnetic measurements established the one-dimensional nature of compound 1 with an antiferromagnetic exchange coupling, J/kB≈-96K, between the MnIII ion and TCNQ radical and with an activated correlation length (Δξ = 26.5K) at low temperatures (50-15 K). The slow relaxation of the magnetization was shown in compound 1 by the field hysteresis of the magnetization observed below 3.5 K (with a coercive field up to 14 kOe at 1.8 K). Single-crystal magnetization measurements demonstrated the uniaxial symmetry of this compound and allowed an estimation of the anisotropy field, Ha≈97 kOe. The absence of magnetic ordered phase or spin-glass behavior was established by heat-capacity calorimetry measurements that exhibit no abnormality of Cp between 0.5 K and 10 K. The study of the magnetization relaxation by combined ac (alternating current) and dc techniques showed that compound 1 possesses a single relaxation time (r). As the consequence of the finite size of the chain, the temperature dependence of r presents two activated regimes above and below 4.5 K with τ01 =2.1 × 10-10 s, Δτ1 = 94.1 K and τ02 = 6.8× 10-8s and Δ τ2 = 67.7 K, respectively. The detailed analysis of these dynamics properties together with the correlation length, allows an unambiguous demonstration of the single-chain magnet behavior in 1.
AB - An alternated 1:1 chain compound of a MnIII salen derivative and the TCNQ monoradical was synthesized: [Mn(5-TMAMsaltmen)-(TCNQ)](ClO 4)2 (1) (TCNQ = tetracyano-p-quinodimethane; 5-TMAM-saltmen = N,N′-(1,1,2,2-tetramethylethylene) bis(5-trimethylammoniomethylsalicylideneiminato)). Compound 1 has a zigzag chain structure packed with adjacent chains with an interchain Mn⋯Mn distance of over 8 Å. As compound 1 contains no crystallization solvent, the void spaces between chains are occupied only by ClO4- counter ions. Compound 1 has a structure reminiscent of what has been observed in the family, of MnIII(porphyrin)-TCNE or -TCNQ compounds reported previously by Miller and co-workers and we demonstrate herein its unique single-chain magnet behavior among this family of compounds. The direct current (dc) magnetic measurements established the one-dimensional nature of compound 1 with an antiferromagnetic exchange coupling, J/kB≈-96K, between the MnIII ion and TCNQ radical and with an activated correlation length (Δξ = 26.5K) at low temperatures (50-15 K). The slow relaxation of the magnetization was shown in compound 1 by the field hysteresis of the magnetization observed below 3.5 K (with a coercive field up to 14 kOe at 1.8 K). Single-crystal magnetization measurements demonstrated the uniaxial symmetry of this compound and allowed an estimation of the anisotropy field, Ha≈97 kOe. The absence of magnetic ordered phase or spin-glass behavior was established by heat-capacity calorimetry measurements that exhibit no abnormality of Cp between 0.5 K and 10 K. The study of the magnetization relaxation by combined ac (alternating current) and dc techniques showed that compound 1 possesses a single relaxation time (r). As the consequence of the finite size of the chain, the temperature dependence of r presents two activated regimes above and below 4.5 K with τ01 =2.1 × 10-10 s, Δτ1 = 94.1 K and τ02 = 6.8× 10-8s and Δ τ2 = 67.7 K, respectively. The detailed analysis of these dynamics properties together with the correlation length, allows an unambiguous demonstration of the single-chain magnet behavior in 1.
KW - Magnetic properties
KW - Manganese
KW - Salen-type ligand
KW - Single-chain magnet
KW - TCNQ
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U2 - 10.1002/chem.200600289
DO - 10.1002/chem.200600289
M3 - Article
C2 - 16892471
AN - SCOPUS:33749020307
VL - 12
SP - 7028
EP - 7040
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 27
ER -