From the FeIII^{III}2_{2}Ln2_{2} Butterfly’s Perspective: the Magnetic Benefits and Challenges of Cooperativity within 3 d–4 f Based Coordination Clusters

The well-known oxo-centred Fe triangle is used to access the vast majority of [Fe$^{III}$$_{2}$Ln$_{2}$(μ$_{3}$-OR)$_{2}$L$_{2}$(O$_{2}$CR)$_{6}$] butterflies, since it provides a di-iron central body unit and carboxylate bridges to the wingtips, which are occupied by supplied Ln ions. The remaining coordination sites of the lanthanide are occupied by a multidentate ligand, which can also provide further bridging. This system provides a useful testbed for exploring multiple variations, for example changing the Ln, the bridging carboxylate and the nature of the chelating ligand. In this Review we discuss the tuning handles which can be used to steer the magnetic properties of Fe$^{III}$-4 f “butterfly” compounds. The majority of presented compounds were produced in the context of project A3 “Di- to tetranuclear compounds incorporating highly anisotropic paramagnetic metal ions” within the SFB/TRR88 “3MET”. These contain {Fe$^{III}$$_{2}$Ln$_{2}$} cores encapsulated in ligand shells which are easy to tune in a “test-bed” system. We identify the following advantages and variables in such systems: (i) the complexes are structurally simple usually with one crystallographically independent Fe$^{III}$ and Ln$^{III}$ respectively. This simplifies theory and anaylsis; (ii) choosing Fe allows $^{57}$Fe Mössbauer spectroscopy to be used as an additional technique which can give information about oxidation levels and spin states, local moments at the iron nuclei and spin-relaxation and, more importantly, about the anisotropy not only of the studied isotope, but also of elements interacting with this isotope; (iii) isostructural analogues with all the available (i. e. not Pm) 4 f ions can be synthesised, enabling a systematic survey of the influence of the 4 f ion on the electronic structure; (iv) this cluster type is obtained by reacting [Fe$^{III}$$_{3}$O(O$_{2}$CR)$_{6}$(L)$_{3}$](X) (X=anion, L=solvent such as H$_{2}$O, py) with an ethanolamine-based ligand L′ and lanthanide salts. This allows to study analogues of [Fe$^{III}$$_{2}$Ln$_{2}$(μ$_{3}$-OH)$_{2}$(L′)$_{2}$(O$_{2}$CR)$_{6}$] using the appropriate iron trinuclear starting materials. (v) the organic main ligand can be readily functionalised, facilitating a systematic investigation of the effect of organic substituents on the ligands on the magnetic properties of the complexes. We describe and discuss 34 {M$^{III}$$_{2}$Ln$_{2}$} (M=Fe or in one case Al) butterfly compounds which have been reported up to 2020. The analysis of these gives perspectives for designing new SMM systems with specific electronic and magnetic signature

Breaking Symmetry Relaxes Structural and Magnetic Restraints, Suppressing QTM in Enantiopure Butterfly Fe2_{2}Dy2_{2} SMMs**

These 2 coordination clusters are similar but different both in the fine details of their structures as well as their magnetic behaviour. [Fe$_{2}$Dy$_{2}$(μ$_{3}$-OH)$_{2}$(Me-teaH)$_{2}$(O$_{2}$CPh)$_{6}$], which normally forms with the racemic version of Me-teaH3 by using enantiopure ligand, allows access to the S-version, but for the R-version there is significant racemisation. Surprisingly, by using the synthesis of [Fe$_{2}$Dy$_{2}$(μ$_{3}$-OH)$_{2}$(Me-teaH)$_{2}$(O$_{2}$CPh)$_{4}$(NO$_{3}$)$_{2}$] both enantiopure R- and S-compounds were obtained. In both cases breaking the symmetry of the parent compounds leads to enhanced SMM behaviour. The {Fe$_{2}$Dy$_{2}$} butterfly systems can show single molecule magnet (SMM) behaviour, the nature of which depends on details of the electronic structure, as previously demonstrated for the [Fe$_{2}$Dy$_{2}$(μ$_{3}$-OH)$_{2}$(Me-teaH)$_{2}$(O$_{2}$CPh)$_{6}$] compound, where the [N,N-bis-(2-hydroxyethyl)-amino]-2-propanol (Me-teaH$_{3}$) ligand is usually used in its racemic form. Here, we describe the consequences for the SMM properties by using enantiopure versions of this ligand and present the first homochiral 3d/4 f SMM, which could only be obtained for the S enantiomer of the ligand for [Fe$_{2}$Dy$_{2}$(μ$_{3}$-OH)$_{2}$(Me-teaH)$_{2}$(O$_{2}$CPh)$_{6}$] since the R enantiomer underwent significant racemisation. To investigate this further, we prepared the [Fe$_{2}$Dy$_{2}$(μ$_{3}$-OH)$_{2}$(Me-teaH)$_{2}$(O$_{2}$CPh)$_{4}$(NO$_{3}$)$_{2}$] version, which could be obtained as the RS-, R- and S-compounds. Remarkably, the enantiopure versions show enhanced slow relaxation of magnetisation. The use of the enantiomerically pure ligand suppresses QTM, leading to the conclusion that use of enantiopure ligands is a “gamechanger” by breaking the cluster symmetry and altering the intimate details of the coordination cluster\u27s molecular structure

Influence of socioeconomic factors on pregnancy outcome in women with structural heart disease

OBJECTIVE: Cardiac disease is the leading cause of indirect maternal mortality. The aim of this study was to analyse to what extent socioeconomic factors influence the outcome of pregnancy in women with heart disease.  METHODS: The Registry of Pregnancy and Cardiac disease is a global prospective registry. For this analysis, countries that enrolled ≥10 patients were included. A combined cardiac endpoint included maternal cardiac death, arrhythmia requiring treatment, heart failure, thromboembolic event, aortic dissection, endocarditis, acute coronary syndrome, hospitalisation for cardiac reason or intervention. Associations between patient characteristics, country characteristics (income inequality expressed as Gini coefficient, health expenditure, schooling, gross domestic product, birth rate and hospital beds) and cardiac endpoints were checked in a three-level model (patient-centre-country).  RESULTS: A total of 30 countries enrolled 2924 patients from 89 centres. At least one endpoint occurred in 645 women (22.1%). Maternal age, New York Heart Association classification and modified WHO risk classification were associated with the combined endpoint and explained 37% of variance in outcome. Gini coefficient and country-specific birth rate explained an additional 4%. There were large differences between the individual countries, but the need for multilevel modelling to account for these differences disappeared after adjustment for patient characteristics, Gini and country-specific birth rate.  CONCLUSION: While there are definite interregional differences in pregnancy outcome in women with cardiac disease, these differences seem to be mainly driven by individual patient characteristics. Adjustment for country characteristics refined the results to a limited extent, but maternal condition seems to be the main determinant of outcome

Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet

Kaemmerer H, Baniodeh A, Peng Y, et al. Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet. Journal of the American Chemical Society. 2020;142(35):4838–14842.Cyclic coordination clusters (CCCs) are proving to provide an extra dimension in terms of exotic magnetic behavior as a result of their finite but cyclized chain structures. The Fe18Dy6 CCC is a Single Molecule Magnet with the highest nuclearity among Ln containing clusters. The three isostructural compounds [Fe18Ln6(mu-OH)6(ampd)12(Hampd)12(PhCO2)24](NO3)6·38MeCN for Ln = DyIII (1), LuIII (2), or YIII (3), where H2ampd = 2-amino-2-methyl-1,3-propanediol, are reported. These can be described in terms of the cyclization of six {Fe3Ln(muOH)(ampd)2(Hampd)2(PhCO2)4}+ units with six nitrate counterions to give the neutral cluster. The overall structure consists of two giant Dy3 triangles sandwiching a strongly antiferromagnetically coupled Fe18 ring, leading to a toroidal arrangement of the anisotropy axis of the Dy ions, making this the biggest toroidal arrangement on a molecular level known so far

Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet

Kaemmerer H, Baniodeh A, Peng Y, et al. Inorganic Approach to Stabilizing Nanoscale Toroidicity in a Tetraicosanuclear Fe18Dy6 Single Molecule Magnet. Journal of the American Chemical Society. 2020;142(35):4838–14842.Cyclic coordination clusters (CCCs) are proving to provide an extra dimension in terms of exotic magnetic behavior as a result of their finite but cyclized chain structures. The Fe18Dy6 CCC is a Single Molecule Magnet with the highest nuclearity among Ln containing clusters. The three isostructural compounds [Fe18Ln6(mu-OH)6(ampd)12(Hampd)12(PhCO2)24](NO3)6·38MeCN for Ln = DyIII (1), LuIII (2), or YIII (3), where H2ampd = 2-amino-2-methyl-1,3-propanediol, are reported. These can be described in terms of the cyclization of six {Fe3Ln(muOH)(ampd)2(Hampd)2(PhCO2)4}+ units with six nitrate counterions to give the neutral cluster. The overall structure consists of two giant Dy3 triangles sandwiching a strongly antiferromagnetically coupled Fe18 ring, leading to a toroidal arrangement of the anisotropy axis of the Dy ions, making this the biggest toroidal arrangement on a molecular level known so far

Pregnancy outcomes in women with rheumatic mitral valve disease: Results from the registry of pregnancy and cardiac disease

BACKGROUND: Cardiac disease is 1 of the major causes of maternal mortality. We studied pregnancy outcomes in women with rheumatic mitral valve disease. METHODS: The Registry of Pregnancy and Cardiac Disease is an international prospective registry, and consecutive pregnant women with cardiac disease were included. Pregnancy outcomes in all women with rheumatic mitral valve disease and no prepregnancy valve replacement is described in the present study (n=390). A maternal cardiac event was defined as cardiac death, arrhythmia requiring treatment, heart failure, thromboembolic event, aortic dissection, endocarditis, acute coronary syndrome, and hospitalization for other cardiac reasons or cardiac intervention. Associations between patient characteristics and cardiac outcomes were checked in a 3-level model (patient-center-country). RESULTS: Most patients came from emerging countries (75%). Mitral stenosis (MS) with or without mitral regurgitation (MR) was present in 273 women, isolated MR in 117. The degree of MS was mild in 20.9%, moderate in 39.2%, severe in 19.8%, and severity not classified in the remainder. Maternal death during pregnancy occurred in 1 patient with severe MS. Hospital admission occurred in 23.1% of the women with MS, and the main reason was heart failure (mild MS 15.8%, moderate 23.4%, severe 48.1%; PCONCLUSIONS: Although mortality was only 1.9% during pregnancy, ∼50% of the patients with severe rheumatic MS and 23% of those with significant MR developed heart failure during pregnancy. Prepregnancy counseling and considering mitral valve interventions in selected patients are important to prevent these complications.</p