Intercalation of Coordinatively Unsaturated FeIII Ion within Interpenetrated Metal–Organic Framework MOF‐5

Coordinatively unsaturated Fe^III metal sites were successfully incorporated into the iconic MOF‐5 framework. This new structure, Fe^III‐iMOF‐5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single‐crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid‐state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe^III, whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe^III ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn^II within the MOF‐5 SBU. This new MOF structure displays the potential for metal‐site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials.     

Studies of a linear single-molecule magnet

Reaction of the dinuclear complex [Mn2O2(bpy)4](ClO4)3 with H3cht (cis,cis-l,3,5-cyclohexanetriol) in MeCN produces the complex [Mn3(Hcht)2(bpy)4](ClO4)3.Et2O.2MeCN (1.Et2O.2MeCN). Dc magnetic susceptibility measurements reveal the existence of weak ferromagnetic exchange between the three Mn ions, leading to a spin ground state of S = 7, with D = -0.23 cm(-1). W-Band (94 GHz) EPR measurements on restrained powdered crystalline samples confirm the S = 7 ground state and determine the ground state zero-field splitting (ZFS) parameters of D = -0.14 cm(-1) and B4(0)= +1.5 x 10(-5) cm(-1). The apparent 4th order behaviour is due to a breakdown of the strong exchange limit approximation (J approximately d, the single-ion ZFS). Single crystal dc relaxation decay and hysteresis loop measurements reveal the molecule to have an appreciable energy barrier to magnetization relaxation, displaying low temperature sweep rate and temperature-dependent hysteresis loops. Density functional studies confirm the ferromagnetic exchange coupling between the Mn ions.     

Lead bipyridyl hexacyanoferrate complex

A low-solubility complex [PbBipy₂]₆[Fe(CN)₆]₄ · Bipy · 14H₂O was prepared and characterized by physicochemical methods. Although containing [PbBipy₂]₂[Fe(CN)₆] discrete species and a {[PbBipy₂][Fe(CN)₆]} _n infinite chain in the crystal structure, the complex has weak antiferromagnetic properties over a wide temperature range. The irreversible thermal destruction of the complex, which starts at 192°C, is preceded by complete dehydration.     

New Mn12 single-molecule magnets from edge-sharing bioctahedra

Dodecanuclear Mn clusters based on edge-sharing bioctahedra display the scan-rate- and temperature-dependent hysteresis loops that are indicative of single-molecule magnetism behaviour.     

A new type of oxygen bridged Cu(II)36 aggregate formed around a central [KCl6]5- unit

A magnetically coupled Cu(II)36 aggregate forms around a potassium chloride unit.     

GC-MS analysis of metabolites from soxhlet extraction,ultrasound-assisted extraction and supercritical fluid extraction of Salacca zalacca flesh and its alpha-glucosidase inhibitory activity

Abstract

Different extraction processes were employed to extract bioactive metabolites from Salacca zalacca flesh by a range of aqueous and organic solvents. The highest extraction yield was obtained by 50% ethanol extract of SE (73.18?±?4.35%), whereas SFE_1 showed the lowest yield (0.42?±?0.08%). All extracts were evaluated for in vitro α-glucosidase inhibitory activity, measured by their IC₅₀ values in comparison to that of quercetin, the positive control (IC₅₀ = 2.7?±?0.7?μg/mL). The lowest α-glucosidase inhibitory activity was indicated by water extract of SE (IC₅₀ = 724.3?±?42.9?μg/mL) and the highest activity was demonstrated by 60% ethanol extract by UAE (IC₅₀ = 16.2?±?2.4?μg/mL). All extracts were analysed by GC-MS and identified metabolites like carbohydrates, fatty acids, organic acids, phenolic acids, sterols and alkane-based compounds etcetera that may possess the potential as α-glucosidase inhibitor and may attribute to the α-glucosidase inhibitory activity.     

Importance of out-of-state spin-orbit coupling for slow magnetic relaxation in mononuclear Fe(II) complexes

Two mononuclear high-spin Fe(II) complexes with trigonal planar ([Fe(II)(N(TMS)(2))(2)(PCy(3))] (1) and distorted tetrahedral ([Fe(II)(N(TMS)(2))(2)(depe)] (2) geometries are reported (TMS = SiMe(3), Cy = cyclohexyl, depe = 1,2-bis(diethylphosphino)ethane). The magnetic properties of 1 and 2 reveal the profound effect of out-of-state spin-orbit coupling (SOC) on slow magnetic relaxation. Complex 1 exhibits slow relaxation of the magnetization under an applied optimal dc field of 600 Oe due to the presence of low-lying electronic excited states that mix with the ground electronic state. This mixing re-introduces orbital angular momentum into the electronic ground state via SOC, and 1 thus behaves as a field-induced single-molecule magnet. In complex 2, the lowest-energy excited states have higher energy due to the ligand field of the distorted tetrahedral geometry. This higher energy gap minimizes out-of-state SOC mixing and zero-field splitting, thus precluding slow relaxation of the magnetization for 2.     

An organometallic sandwich lanthanide single-ion magnet with an unusual multiple relaxation mechanism

A dysprosium(III) sandwich complex, [Dy(III)(COT″)(2)Li(THF)(DME)], was synthesized using 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion (COT″). The complex behaves as a single-ion magnet and demonstrates unusual multiple relaxation modes. The observed relaxation pathways strongly depend on the applied static dc fields.