内部分子桥梁策略,以抑制双声波拉曼旋转放松在dysprosocenium单分子磁铁中的放松
Jakob K Staab1, Md Kholilur Rahman1, Nicholas F Chilton1,2
1Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK.
Physical chemistry chemical physics : PCCP
|June 17, 2024
概括
研究人员通过桥接连体抑制了双 (III) 二cyclopentadienyl单分子磁体 (SMM) 中的拉曼放松. 这一策略通过减少振动干扰来增强磁性记忆效应,这对于推进SMM技术至关重要.
科学领域:
- 材料科学 材料科学 材料科学
- 量子化学 是一个量子化学.
- 凝聚物质物理学 凝聚物质物理学
背景情况:
- 双 (III) 双cyclopentadienyl (Cp) 化合物是领先的单分子磁铁 (SMMs) 由于强大的磁性异构和记忆效应.
- 目前的SMM设计侧重于最大限度地提高异构性障碍,增加有效的激活能量 (Ueff) 和减缓Orbach放松.
- 两声波拉曼旋转放松仍然是一个瓶,限制了SMM工作温度.
研究的目的:
- 为了研究在Dy(III) SMM中抑制拉曼放松.
- 测试假设,增加连接体框架刚度会减少低频振动,从而抑制拉曼放松.
- 探索Cp连接体对磁放松动态的共价桥接的影响.
主要方法:
- 模拟的奥巴赫和拉曼旋转放松使用量子力学/分子力学 (QM/MM) 凝聚相嵌入协议.
- 采用周期性溶剂矩阵来建模凝聚相环境,包括语音自由度.
- 研究了一系列零,单,二和三桥的[Dy(Cp^ttt) 2+类似物.
主要成果:
- QM/MM模型准确地模拟了一个非桥接[Dy(Cp^ttt) 2+化合物的磁放松动态.
- 单桥式SMM显著减缓了拉曼放松,而进一步的桥梁加速了它.
- 拉曼放松率与第一次激发的克莱默斯双倍的mJ含量的纯度相关 = ±13/2.
结论:
- 共振桥可以有效地重塑状态的振动密度,以抑制SMM中的拉曼放松.
- 虽然桥梁修改了振动特性,但它也可以降低磁性异构性,需要精细的链接器化学.
- 周期性溶剂嵌入模型准确地预测了凝结相分子自旋动力学,而不需要晶体结构.
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