Bennett Tom S, Lockyer Selena J, Asthana Deepak, Whitehead George F S, Vitorica-Yrezabal Inigo J, Timco Grigore A, Winpenny Richard E P, McInnes Eric J L
Department of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.
Chem Asian J. 2024 Oct 16;19(20):e202400641. doi: 10.1002/asia.202400641. Epub 2024 Sep 24.
Mono- and bis-salen functionalised [2]rotaxanes have been synthesised from the esterification of [2]rotaxanes containing phenol-terminated threads (salen=N,N'-bis(salicylidene)ethylenediamine). The [2]rotaxanes have general formula [RH][CrNiF(OCBu)], where [RH] is a thread with a central secondary ammonium site that templates a [CrNiF(OCBu)] ring. The threads are terminated at one or both ends by carboxylic acid functionalised salen groups. The {M(salen)} groups can be free-base [M=(H)] or metallated [M=Cu, Ni, (VO)]. The [2]rotaxanes have been characterised by single crystal XRD and solid- and solution-state EPR spectroscopy. Where two paramagnetic M ions are involved [M=Cu and/or (VO)] the [2]rotaxanes contain three electron spin S= centres, since the {CrNi} ring has an S= ground state which is well isolated at low temperatures. These three-spin [2]rotaxanes have been characterised in solution by pulsed dipolar EPR spectroscopies (DEER, also known as PELDOR, and RIDME). The M⋅⋅⋅M and M⋅⋅⋅{CrNi} interactions measured are consistent with dipolar interactions and also with the distances from single crystal XRD. The authors declare no competing financial interest.
单-和双-萨伦功能化的[2]轮烷是由含酚端基链的[2]轮烷（萨伦=N,N'-双（水杨醛）乙二胺）酯化合成的。[2]轮烷的通式为[RH][CrNiF(OCBu)]，其中[RH]是一条带有中心仲铵位点的链，该位点作为[CrNiF(OCBu)]环的模板。链的一端或两端由羧酸功能化的萨伦基团终止。{M(萨伦)}基团可以是游离碱[M=(H)]或金属化的[M=Cu、Ni、(VO)]。[2]轮烷已通过单晶XRD以及固态和溶液态EPR光谱进行了表征。当涉及两个顺磁M离子时[M=Cu和/或(VO)]，[2]轮烷包含三个电子自旋S = 中心，因为{CrNi}环具有S = 的基态，在低温下该基态很好地隔离。这些三自旋[2]轮烷已通过脉冲偶极EPR光谱（DEER，也称为PELDOR和RIDME）在溶液中进行了表征。测量的M⋅⋅⋅M和M⋅⋅⋅{CrNi}相互作用与偶极相互作用一致，也与单晶XRD得到的距离一致。作者声明不存在相互竞争的财务利益。
