A Family of Layered Chiral Porous Magnets Exhibiting Tunable Ordering Temperatures

A simple change of the substituents in the bridging ligand allows tuning of the ordering temperatures, Tc, in the new family of layered chiral magnets A­[MIIMIII(X2An)3]·G (A = [(H3O)­(phz)3]+ (phz = phenazine) or NBu4+; X2An2– = C6O4X22– = 2,5-dihydroxy-1,4-benzoquinone derivative dianion, with MIII = Cr, Fe; MII = Mn, Fe, Co, etc.; X = Cl, Br, I, H; G = water or acetone). Depending on the nature of X, an increase in Tc from ca. 5.5 to 6.3, 8.2, and 11.0 K (for X = Cl, Br, I, and H, respectively) is observed in the MnCr derivative. Furthermore, the presence of the chiral cation [(H3O)­(phz)3]+, formed by the association of a hydronium ion with three phenazine molecules, leads to a chiral structure where the Δ-[(H3O)­(phz)3]+ cations are always located below the Δ-[Cr­(Cl2An)3]3– centers, leading to a very unusual localization of both kinds of metals (Cr and Mn) and to an eclipsed disposition of the layers. This eclipsed disposition generates hexagonal channels with a void volume of ca. 20% where guest molecules (acetone and water) can be reversibly absorbed. Here we present the structural and magnetic characterization of this new family of anilato-based molecular magnets.

通过简单调控桥联配体（bridging ligand）上的取代基，可调控该新型层状手性磁体家族A[MIIMIII(X2An)3]·G的相变温度Tc。其中，A为[(H3O)(phz)3]+（phz = 吩嗪（phenazine））或四丁基铵阳离子（NBu4+）；X2An2– = C6O4X22– = 2,5-二羟基-1,4-苯醌衍生物二价阴离子；MIII为Cr、Fe；MII为Mn、Fe、Co等；X为Cl、Br、I、H；G为水或丙酮。以MnCr衍生物为例，根据X的种类不同，Tc可从约5.5 K依次提升至6.3 K、8.2 K和11.0 K（对应X分别为Cl、Br、I、H）。此外，由水合氢离子与三个吩嗪分子结合形成的手性阳离子[(H3O)(phz)3]+，可构建出手性结构：Δ-[(H3O)(phz)3]+阳离子始终位于Δ-[Cr(Cl2An)3]3–中心的下方，这使得Cr与Mn两类金属呈现极为罕见的局部分布模式，并使各磁层呈现重叠排布。该层间重叠排布可形成孔隙率约20%的六方通道，可可逆吸附丙酮与水等客体分子。本文报道了这一类anilato基分子磁体的结构与磁学表征。