Authors: Emilia Kuźniak | Piotr Konieczny | Robert Pełka | Tadeusz M. Muzioł | Marcin Kozieł | Robert Podgajny
Source: Inorganic Chemistry (article, 2021-07-07)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Engineering of the <i>XY</i> Magnetic Layered System with Adeninium Cations: Monocrystalline Angle-Resolved Studies of Nonlinear Magnetic Susceptibility An original example of <i>modular</i> crystal engineering involving molecular magnetic {Cu<sup>II</sup>[W<sup>V</sup>(CN)<sub>8</sub>]}<sup>-</sup> bilayers and adeninium cations (AdeH<sup>+</sup>) toward the new layered molecular magnet (AdeH){Cu<sup>II</sup>[W<sup>V</sup>(CN)<sub>8</sub>]}·2H<sub>2</sub>O (<b>1</b>) is presented. <b>1</b> crystallizes within the monoclinic <i>C</i>2 space group (<i>a</i> = 41.3174(12), <i>b</i> = 7.0727(3), <i>c</i> = 7.3180(2) Å, β = 93.119(3)°, and <i>V</i> = 2135 Å<sup>3</sup>). The bilayer topology is based on a stereochemical matching between the square pyramidal shape of Cu<sup>II</sup> moiety and the bicapped trigonal prismatic shape of [W<sup>V</sup>(μ-CN)<sub>5</sub>(CN)<sub>3</sub>], and the separation between bilayers is significantly increased (by ∼50%; from ca. 9.5 to ca. 14.5 Å) compared to several former analogues in this family. This was achieved via a unique combination of (i) a 1D ribbonlike hydrogen bond system {AdeH<sup>+</sup>···H<sub>2</sub>O···AdeH<sup>+</sup>···}<sub>∞</sub> exploiting planar water-assisted Hoogsteen···Sugar synthons with (ii) parallel 1D π-π stacks {AdeH<sup>+</sup>···AdeH<sup>+</sup>}<sub>∞</sub>. In-plane 2D <i>XY</i> magnetism is characterized by a <i>T</i><sub>c</sub> close to 33 K, <i>H</i><sub>c,in-plane</sub> = 60 Oe, and <i>H</i><sub>c,out-of-plane</sub> = 750 Oe, high values of in-plane γ critical exponents (γ<sub>b</sub> = 2.34(6) for <i>H</i>||<i>b</i> and γ<sub>c</sub> = 2.16(5) for <i>H</i>||<i>c</i>), and a Berezinskii-Kosterlitz-Thouless (BKT) topological phase transition, deduced from crystal-orientation-dependent scaling analysis. The obtained values of in-plane ν critical exponents, ν<sub><i>b</i></sub> = 0.48(5) for <i>H</i>||<i>b</i> and ν<sub><i>c</i></sub> = 0.49(3) for <i>H</i>||<i>c</i>, confirm the BKT transition (ν<sub>BKT</sub> = 0.5). Full-range angle-resolved monocrystalline magnetic measurements supported by dedicated calculations indicated the occurrence of nonlinear susceptibility performance within the easy plane in a magnetically ordered state. We refer the occurrence of this phenomenon to spontaneous resolution in the <i>C</i>2 space group, a tandem not observed in studies on previous analogues and rarely reported in the field of molecular materials. The above <i>magneto-supramolecular strategy</i> may provide a novel means for the design of 2D molecular magnetic networks and help to uncover the inherent phenomena. Chemistry ; Crystallography ; Monocrystalline silicon ; Magnetic susceptibility ; Hydrogen bond ; Crystal structure ; Monoclinic crystal system ; Condensed matter physics ; Topology (electrical circuits) ; Physics ; Molecule ; Silicon Magnetism in coordination complexes ; Metal-Organic Frameworks: Synthesis and Applications ; Organic and Molecular Conductors Research