Crystalline bilayer formation in homoleptic low-spin Fe(II) compounds with alkyl chain substituents.

A series of asymmetric, homoleptic Fe(II) compounds based on the facially-binding tridentate ligand -methyl-1,1-di(pyridin-2-yl)C-amine (LC) (C = butyl, hexyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl alkyl chains) with formula [Fe(LC)](X)·solvate, where = 4, 14 and X = BF (1C4 and 1C14) or = 6, 8, 10, 12, 16 and X = CFSO (1C6-1C12 and 1C16), are reported. Complexes 1C6 to 1C16 pack in crystalline bilayers in the solid state, forming hydrophobic and hydrophilic regions between adjacent layers of complexes. The combination of short Fe-N bond distances (∼2.

Synthesis, mixed-spin-state structure and Langmuir-Blodgett deposition of amphiphilic Fe(iii) quinolylsalicylaldiminate complexes.

Designing and integrating Fe(iii)-based spin crossover (SCO) complexes onto substrates remains a challenging goal with only a handful of examples reported. In this work, we successfully synthesized and characterized three [Fe(qsal-OR)]NO (qsal-OR = 5-alkoxy-2-[(8-quinolylimino)methyl]phenolate) complexes, in which R = CH1, CH2, and CH3 to explore the impact of alkyl chain on the modulation of SCO activity and potential for self-assembly on a glass surface. The SCO is found to be gradual and incomplete in all cases, with the LS state more stabilised as the alkyl group shortens.

Learning to use landmarks for navigation amplifies their representation in retrosplenial cortex.

Visual landmarks provide powerful reference signals for efficient navigation by altering the activity of spatially tuned neurons, such as place cells, head direction cells, and grid cells. To understand the neural mechanism by which landmarks exert such strong influence, it is necessary to identify how these visual features gain spatial meaning. In this study, we characterized visual landmark representations in mouse retrosplenial cortex (RSC) using chronic two-photon imaging of the same neuronal ensembles over the course of spatial learning.

Inelastic Neutron Scattering Measurement of the Ground State Tunneling Gap in Tb and Ho Analogues of a Dy Field-Induced Single-Molecule Magnet.

Recent advances in single-molecule magnet (SMM) research have placed great value on interpretation of inelastic neutron scattering (INS) data for rare earth (RE)-containing SMMs. Here, we present the synthesis of several rare earth complexes where combined magnetic and INS studies have been performed, supported by calculations. The reaction of rare earth nitrate salts with 2,2'-bipyridine (2,2'-bpy) and tetrahalocatecholate (XCat, X = Br, Cl) ligands in methanol (MeOH) afforded two new families of compounds [RE(2,2'-bpy)(XCat)(XCatH)(MeOH)] (X = Br and RE = Y, Eu, Gd, Tb, Dy, Ho, Yb for ; X = Cl and RE = Y, Tb, Dy, Ho, and Yb for ).

Efficient synthetic route to heterobimetallic trinuclear complexes [Ln-Mn-Ln] and their single molecule magnetic properties.

A series of mononuclear lanthanoidate complexes isolated as [BuN][Ln(QCl)] 1Ln (QCl = 5-chloro-8-quinolinolate; Ln = Eu, Gd, Tb, Dy, Ho, and Er) have been prepared, characterised, and used as facile precursors to obtain a series of new heterobimetallic complexes as crystalline materials. Reaction of 1Ln with manganese nitrate forms [LnMn(QCl)] (2Ln, where Ln = Tb, Dy, Er and Yb) which have been structurally characterised in the cases of 2Tb and 2Yb. The heteroleptic trinuclear complex [Dy(QCl)Cl(OH)], 3, has also been obtained.

Emergence of Direction-Selective Retinal Cell Types in Task-Optimized Deep Learning Models.

Convolutional neural networks (CNNs), a class of deep learning models, have experienced recent success in modeling sensory cortices and retinal circuits through optimizing performance on machine learning tasks, otherwise known as task optimization. Previous research has shown task-optimized CNNs to be capable of providing explanations as to why the retina efficiently encodes natural stimuli and how certain retinal cell types are involved in efficient encoding. In our work, we sought to use task-optimized CNNs as a means of explaining computational mechanisms responsible for motion-selective retinal circuits.

Enhancing the barrier height for magnetization reversal in 4d/4f RuIII2LnIII2 "butterfly" single molecule magnets (Ln = Gd, Dy) targeted structural alterations.

A series of 4d-4f {RuIII2DyIII2} and {RuIII2GdIII2} 'butterfly' (rhombohedral) complexes have been synthesized and characterized and their magnetic properties investigated. Earlier, we have reported the first 4d/4f SMM - [RuIII2DyIII2(OMe)(OCPh)(mdea)(NO)] (1Dy) with a value of 10.7 cm.

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches.

The ability to identify promising candidate switchable molecules computationally, prior to synthesis, represents a considerable advance in the development of switchable molecular materials. Even more useful would be the possibility of predicting the switching temperature. Cobalt-dioxolene complexes can exhibit thermally induced valence tautomeric switching between low-spin Co-catecholate and high-spin Co-semiquinonate forms, where the half-temperature () is the temperature at which there are equal amounts of the two tautomers.

Lanthanoid pyridyl-β-diketonate 'triangles'. New examples of single molecule toroics.

Trinuclear lanthanoid clusters have been synthesised and investigated as toroidal spin systems. A pyridyl functionalised β-diketonate, 1,3-bis(pyridin-2-yl)propane-1,3-dione (o-dppdH) has been used to synthesise a family of clusters of the form [Dy3(OH)2(o-dppd)3Cl2(H2O)4]Cl2·7H2O (1), [Tb3(o-dppd)3(μ3-OH)2(CH3CH2OH)3Cl3][Tb3(o-dppd)3(μ3-OH)2(H2O)(CH3CH2OH)2Cl3]Cl2·H2O (2), [Ho3(OH)2(o-dppd)3Cl(H2O)5]Cl3·3H2O (3) and [Er3(OH)2(o-dppd)3Cl2(H2O)3(CH3OH)]Cl2·3H2O·CH3OH (4). Despite the previous occurrence of this structural motif in the literature, these systems have not been widely investigated in terms of torodic behaviour.

Development of a compact imaging spectrometer form for the solar reflective spectral region.

Current imaging spectrometer forms for terrestrial remote sensing in the visible, near-, and shortwave infrared (VNR/SWIR) spectral range have been implemented in hardware and achieve a high level of performance in terms of both aberration control and signal-to-noise level. These forms are compact, relative to prior art, but more size, weight, and power optimization, while maintaining performance, is desirable for usage on small satellite platforms. Pursuant to that goal, we have developed a compact breadboard prototype VNIR/SWIR imaging spectrometer that maintains the current aberration control and has a large number of spatial samples.

Spin Crossover in Iron(III) Quinolylsalicylaldiminates: The Curious Case of [Fe(qsal-F)](Anion).

A family of iron(III) spin crossover complexes with different counteranions, [Fe(qsal-F)]A (qsal-F = 4-fluoro-2-[(8-quinolylimino)methyl]phenolate; A = PF , OTf , NO , ClO , BF , or NCS ) have been prepared. All compounds are isostructural and crystallize (triclinic 1̅ space group) with two independent iron(III) centers (Fe1 and Fe2) in the asymmetric unit. No solvent molecules are found in the crystal lattice, allowing us to directly probe the relative influence of anion variation on the spin crossover characteristics.

Interactions of emerging contaminants with model colloidal microplastics, C fullerene, and natural organic matter - effect of surface functional group and adsorbate properties.

Surface adsorption of two commonly detected emerging contaminants, amlodipine (AMP) and carbamazepine (CBZ), onto model colloidal microplastics, natural organic matter (NOM), and fullerene nanomaterials have been investigated. It is found that AMP accumulation at these colloidal-aqueous interfaces is markedly higher than that of CBZ. Measurements of surface excess and particle zeta potential, along with pH-dependent adsorption studies, reveal a distinct influence of colloidal functional group on the adsorption properties of these pharmaceuticals.

Tree of Life Synagogue Shooting in Pittsburgh: Preparedness, Prehospital Care, and Lessons Learned.

On Saturday, October 27, 2018, a man with anti-Semitic motivations entered Tree of Life synagogue in the Squirrel Hill section of Pittsburgh, Pennsylvania; he had an AR-15 semi-automatic rifle and three handguns, opening fire upon worshippers. Eventually 11 civilians died at the scene and eight people sustained non-fatal injuries, including five police officers. Each person injured but alive at the scene received care at one of three local level-one trauma centers.

Effects of Mixed Valency in an Fe-Based Framework: Coexistence of Slow Magnetic Relaxation, Semiconductivity, and Redox Activity.

A 2-D coordination framework, (NEt)[Fe(fan)] (; Hfan = 3,6-difluoro-2,5-dihydroxy-1,4-benzoquinone), was synthesized and structurally characterized. The compound is structurally analogous to a formerly elucidated framework, (NEt)[Fe(can)] (Hcan = 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone), and adopts a 2-D (6,3) topology with the symmetrical stacking of [Fe(fan)] sheets that are held in position by the NEt cations between the sheets. The investigation of the dc and ac magnetic properties of revealed ferromagnetic ordering behavior and slow magnetization relaxation, as evinced from ac susceptibility measurements.

Single-ion anisotropy and exchange coupling in cobalt(ii)-radical complexes: insights from magnetic and studies.

The concurrent effects of single-ion anisotropy and exchange interactions on the electronic structure and magnetization dynamics have been analyzed for a cobalt(ii)-semiquinonate complex. Analogs containing diamagnetic catecholate and tropolonate ligands were employed for comparison of the magnetic behavior and zinc congeners assisted with the spectroscopic characterization and assessment of intermolecular interactions in the cobalt(ii) compounds. Low temperature X-band ( ≈ 9.

Hysteretic thermal spin-crossover in heteroleptic Fe(ii) complexes using alkyl chain substituted 2,2'-dipyridylamine ligands.

The alkyl chain carrying ligands N,N-di(pyridin-2-yl)butanamide (LC4) and N,N-di(pyridin-2-yl)decanamide (LC10) were combined with NCS- co-ligands to form the neutral heteroleptic Fe(ii) complexes trans-[FeII(LC4)2(NCS)2] (1C4) and trans-[FeII(LC10)2(NCS)2] (1C10). Variable temperature crystallographic studies revealed that 1C4 is in the orthorhombic space group Pna21 between 85-200 K whereas 1C10 is in the monoclinic space group P21/c between 85-140 K. The average Fe-N bond lengths suggest that at 85 K 1C4 contains LS Fe(ii) centres; however, the ca.

Double spin crossovers: a new double salt strategy to improve magnetic and memory properties.

The structural, magnetic and Mössbauer spectral properties of a double salt, mixed-valent material, [Fe(3,5-MeTPM)(TPM)][Fe(azp)]ClO·2MeCN, 1, reveal spin transitions occur at both the metal sites, with hysteresis, indicative of 1 being a double spin crossover material.

New examples of triangular terbium(iii) and holmium(iii) and hexagonal dysprosium(iii) single molecule toroics.

The structural, magnetic and theoretical aspects are described for three triangular lanthanide complexes, [Tb(OH)(teaH)(paa)]Cl (1), [Dy(OH)(teaH)(paa)]Cl (2) and [Ho(OH)(teaH)(paa)]Cl (3), and a hexanuclear wheel of formula [Dy(pdeaH)(NO)] (4) [teaH = triethanolamine, paaH = N-(2-pyridyl)-acetoacetamide and pdeaH = 3-[bis(2-hydroxyethyl)amino]propan-1-ol]. Each complex displays single molecule toroidal behaviour as rationalised using high-level ab initio calculations. Complexes 2 and 3 are the first examples of mixed moment single molecule toroidal complexes featuring non-Kramers ions.

Tetraoxolene-bridged rare-earth complexes: a radical-bridged dinuclear Dy single-molecule magnet.

Two families of neutral tetraoxolene-bridged dinuclear rare earth complexes of general formula [((HBpz)RE)(μ-tetraoxolene)] (RE = Y and Dy; HBpz = hydrotris(pyrazolyl)borate; tetraoxolene = fluoranilate (fa; 1-RE) or bromanilate (ba; 2-RE)) have been synthesised and characterised. In each case, the bridging tetraoxolene ligand is in the diamagnetic dianionic form and each rare earth metal centre has two HBpz ligands completing the coordination. Electrochemical studies on the soluble 2-RE family reveal a tetraoxolene-based reversible one-electron reduction.

Abrupt spin crossover in iron(iii) complexes with aromatic anions.

Two iron(iii) spin crossover complexes, [Fe(qsal-X)]OTs·nHO, (Br 1·HO; I, 2·2HO or non-solvated 1, 2) have been prepared and fully characterized. Structural studies of 1·HO and 2·2HO reveal the presence of 1D π-π chains linking the Fe(iii) centres and a strong XO halogen bond. In both complexes the 1D π-π chains are angled relative to each other, enforced by C-HX interactions.

The First Observation of Hidden Hysteresis in an Iron(III) Spin-Crossover Complex.

Molecular magnetic switches are expected to form the functional components of future nanodevices. Herein we combine detailed (photo-) crystallography and magnetic studies to reveal the unusual switching properties of an iron(III) complex, between low (LS) and high (HS) spin states. On cooling, it exhibits a partial thermal conversion associated with a reconstructive phase transition from a [HS-HS] to a [LS-HS] phase with a hysteresis of 25 K.

Square Grid Metal-Chloranilate Networks as Robust Host Systems for Guest Sorption.

Reaction of the chloranilate dianion with Y(NO ) in the presence of Et N in the appropriate proportions results in the formation of (Et N)[Y(can) ], which consists of anionic square-grid coordination polymer sheets with interleaved layers of counter-cations. These counter-cations, which serve as squat pillars between [Y(can) ] sheets, lead to alignment of the square grid sheets and the subsequent generation of square channels running perpendicular to the sheets. The crystals are found to be porous and retain crystallinity following cycles of adsorption and desorption.

Oblate versus Prolate Electron Density of Lanthanide Ions: A Design Criterion for Engineering Toroidal Moments? A Case Study on {Ln } (Ln=Tb, Dy, Ho and Er) Wheels.

We report four new complexes based on a {Ln } wheel structure, three of which possess a net toroidal magnetic moment. The four examples consist of {Tb } and {Ho } wheels, which are rare examples of non Dy based complexes possessing a toroidal magnetic ground state, and a {Dy } complex which improves its toroidal structure upon lowering the crystallographic symmetry from trigonal (R ) to triclinic (P ). Notably the toroidal moment is lost for the trigonal {Er } analogue.

Solvatomorphism and anion effects in predominantly low spin iron(iii) Schiff base complexes.

A series of iron(iii) complexes [Fe(naphEen)2]X·sol (naphEen = 1-{[2-(ethylamino)-ethylimino]methyl}-2-naphtholate; X = F, sol = 0.5CH2Cl2·H2O 1; sol = H2O, X = Cl, 2 and X = Br 3) and [Fe(naphEen)2]I 4 has been prepared. The UV-Vis spectra reveal clear differences for 1 which DFT/TDDFT calculations suggest are due to an equilibrium between [Fe(naphEen)2]F and [Fe(naphEen)2F], the latter having a coordinated F ligand.