A meeting of two magnetic worlds: The giant (ca. 4.2 nm) {Mn84} cluster, shown, has a torus structure and is single-molecule magnet (SMM). It represents the molecular (bottom-up) classical (top-down) approaches to nanoscale materials, it crystallizes as nanotubular stacks. discovery that individual molecules can function magnets provided new, "bottom-up" approach materials,1–3 such have since been called (SMMs).4 Each molecule single-domain particle that, below its blocking temperature,...

The preparation of a new family mixed transition metal/lanthanide clusters is reported. reaction [Mn3O(O2CPh)6(py)2(H2O)] with Ln(NO3)3 (Ln = Nd, Gd, Dy, Ho, and Eu) in 1:2 molar ratio MeOH/MeCN (1:20 v/v) leads to dark crystals 55−60% isolated yield complexes all containing the [Mn11Ln4]45+ core. Dy compound has been found give out-of-phase AC susceptibility signals, suggesting it might be single-molecule magnet (SMM). This was confirmed by observation magnetization hysteresis loops. An...

A series of alkyl-substituted and unsubstituted poly(3,4-alkylenedioxythiophene)s were synthesized electrochemically using 3,4-alkylenedioxythiophene derivative monomers where either the size alkylenedioxy ring or nature pendent group was varied. The specific systems studied include 3,4-ethylenedioxythiophene (EDOT), 2-methyl-2,3-dihydrothieno[3,4-b][1,4]dioxine (EDOT-Me), 2-tetradecyl-2,3-dihydrothieno[3,4-b][1,4]dioxine (EDOT-C14H29), 2-phenyl-2,3-dihydrothieno[3,4-b][1,4]dioxine...

The reaction of MnCl2·4H2O (3 equiv), pyridine-2,6-dimethanol (pdmH2) (10 and NaN3 equiv) in MeOH/MeCN (1:2 v/v) with NMe4OH (1 gave [Mn25O18(OH)2(N3)12(pdm)6(pdmH)6](Cl)2·12MeCN (1·12MeCN) ∼30% yield. cation complex 1 comprises five Mnx layers three types an ABCBA arrangement. Fitting variable-temperature -field magnetization data establishes that has S = 51/2 ground state, the largest value for a molecular species. also displays hysteresis loops below 0.6 K vs applied field sweeps,...

This report describes the synthesis and characterization of boronate ester-cross-linked hydrogels capable self-healing behavior at neutral acidic pH. atypically wide pH range over which healing is observed was achieved through use an intramolecular coordinating boronic acid monomer, 2-acrylamidophenylboronic (2APBA), where internal coordination helped to stabilize cross-links formed Two different were from a 2APBA copolymer cross-linked with either poly(vinyl alcohol) or...

The laboratory synthesis of the oxygen-evolving complex (OEC) photosystem II has been objective synthetic chemists since early 1970s. However, absence structural information on OEC hampered these efforts. Crystallographic reports that have appearing at ever-improving resolution over past ten years finally provided invaluable and show it comprises a [Mn 3 CaO 4 ] distorted cubane, to which is attached fourth, external Mn atom, whole unit polypeptides primarily by aspartate glutamate...

Spin doctoring: The already high spin of S=51/2 a Mn25 complex has been pushed even higher, by approximately 20 %, to S=61/2 targeted substitution the azide ligands with an N,O-chelating group. This significant adjustment, or tweaking, suggests general possibility that given type complicated, high-nuclearity, high-spin molecule can exhibit differing ground states appropriate modification peripheral ligation.

Azines made by the reaction of hydrazine with ortho-formylbenzoic acid react 1,2-diphosphinobenzene and either succinyl chloride or phthaloyl in ca. 30% yield to give rac-bis-3,4-diazaphospholanes bearing benzoic groups 2 5 positions. Condensation functionalities enantiomerically pure amines affords diastereomeric benzoamides which can be separated flash chromatography. Application resolved bis-3,4-diazaphosholanes Rh-catalyzed enantioselective hydroformylation styrene, allyl cyanide, vinyl...

Magnetischer Schulterschluss: Der ringförmige Riesencluster {Mn84} (Ø ca. 4.2 nm) verhält sich wie ein Einzelmolekülmagnet und kristallisiert in Form stapelförmiger Aggregate. Molekulare (bottom-up) klassische Ansätze (top-down) zum Aufbau nanoskaliger magnetischer Materialien werden hierdurch kombiniert.

Novel chiral dinuclear Co(II)-salen catalysts self-assembled through the pyridone/aminopyridine hydrogen-bonding pair have been developed. The Co(II)-Salen catalyst results in significant rate acceleration (48 times faster rate) as well excellent enantioselectivity (96% ee vs 55% ee) a nitro-aldol reaction, compared to corresponding monomeric catalyst. A bimetallic mechanism is suggested by kinetic experiment showing that law second order [catalyst]. self-assembly hydrogen bonding was...

Taking the high road: The unification of azide and hmp− (hmpH=2-(hydroxymethyl)pyridine) ligands has provided a route to two salts new Mn10 cation with an aesthetically pleasing, high-symmetry structure. (see excerpt structure; MnII yellow, MnIII blue, O red, N green, C gray) is completely ferromagnetically coupled possesses S=22 ground state, one highest values ever reported.

Detailed studies are reported of a Mn12 single-molecule magnet (SMM) in truly axial (tetragonal) symmetry. The complex is [Mn12O12(O2CCH2Br)16(H2O)4]·4CH2Cl2 (2·4CH2Cl2 or Mn12−BrAc), obtained by the standard carboxylate substitution method. has an S = 10 ground state, typical family, and displays frequency-dependent out-of-phase AC susceptibility signals hysteresis single-crystal magnetization vs applied DC field sweeps. Single-crystal high-frequency EPR spectra frequencies up to 360 GHz...

We report on the comparison of electronic and photophysical properties a series related donor–acceptor–donor oligomers incorporating previously known 2H-benzo[d][1,2,3]triazole (BTz) moiety as acceptor recently reported BTzTD acceptor, hybrid BTz 2,1,3-benzothiadiazole (BTD). Although often implied in polymer literature that has good character, we show this is best described weak acceptor. present electrochemical, computational, evidence supporting our assertion strong electron while...

A new strategy for increasing the barrier to rotation in biaryls has been developed that allows incorporation of 5-membered aromatic heterocycles into chiral atropisomers. Using this concept, an imidazole-based biaryl P,N-ligand designed and prepared as a single enantiomer. This ligand performs exceptionally well enantioselective A3-coupling, demonstrating potential design element.

Reaction of a trinuclear iron(II) complex, Fe3 Br3 L (1), with KC8 under N2 leads to dinitrogen activation products (2) from which (NH)3 (2-1; is cyclophane bridged by three β-diketiminate arms) was characterized X-ray crystallography. (1) H NMR spectra the protonolysis product 2 synthesized (14) and (15) confirm atmospheric reduction, ammonia detected indophenol assay (yield ∼30 %). IR Mössbauer spectroscopy, elemental analysis on 2-1 as well tri(amido)triiron(II) 3 tri(methoxo)triiron 4...

The tungsten alkylidyne [tBuOCO]W≡C(tBu) (THF)2 (1) reacts with CO2, leading to complete cleavage of one C═O bond, followed by migratory insertion generate the tungsten-oxo alkylidene 2. Complex 2 is first catalyst polymerize norbornene via ring expansion metathesis polymerization yield highly cis-syndiotactic cyclic polynorbornene.

A series of poly(3,4-alkylenedioxypyrrole)s are reported as a new class electronically conducting polymers exhibiting especially low oxidation potentials from ca. −0.6 to −0.4 V vs Fc/Fc+ (equivalent −0.15 +0.05 SCE) desired for ambient stability the doped and states. These exhibit unique combinations multicolor electrochromism, switching red or orange neutral state light blue/gray state, passing through darker intermediate (brown), examined by in situ colorimetry. High spectral contrast...

Loopy about magnetism: The use of N-methyldiethanolamine (mdaH2) leads to new Mn12 and Mn4 single-molecule magnets (SMMs) with S=7 S=9 ground-state spins, respectively. species (see structure: MnIII green, MnII orange, O red, N blue, C gray) is a rare example an SMM loop structure. Its unusual ground state for MnIII6MnII6 rationalized by DFT calculations.

Off the shelf: The commercially available ligand (R,R)-1,2-bis(2,5-diphenylphospholano)ethane ((R,R)-Ph-bpe) has been identified as an excellent for asymmetric hydroformylation. State-of-the-art regio- and enantioselectivities are obtained reactions with styrene, allyl cyanide, vinyl acetate substrates while high reaction rates (>4000 turnovers h−1) maintained (see scheme; Ac=acetate, b/l=branched/linear). Supporting information this article is on WWW under...

The complex [Mn(12)O(12)(O(2)CCHCl(2))(16)(H(2)O)(4)] (2) in MeCN exhibits three quasi-reversible one-electron reduction processes at significantly higher potentials than [Mn(12)O(12)(O(2)CMe)(16)(H(2)O)(4)] (1). This has allowed the two-electron reduced version of 2 to be generated and isolated. Reaction with one two equivalents PPh(4)I led isolation (PPh(4))[Mn(12)O(12)(O(2)CCHCl(2))(16)(H(2)O)(4)] (3) (PPh(4))(2)[Mn(12)O(12)(O(2)CCHCl(2))(16)(H(2)O)(4)] (4), respectively. latter...

We report the synthesis of dibutyl derivative poly(3,4-propylenedioxythiophene) as a regiosymmetric and soluble electroactive photoluminescent conjugated polymer obtained in neutral form by Grignard metathesis coupling reaction. Molecular weights have been characterized gel permeation chromatography (GPC) matrix-assisted laser desorption/ionization time-of-flight (MALDI−TOF) mass spectrometry, latter showing end groups due to H/H, H/Br, Br/Br termini. Solution-cast films PProDOT-Bu2 are...