Helical Chiral Catalysts: The gram-scale synthesis of 1-azahelicenes, structural characterization the corresponding N-oxides, and application this new family catalysts to catalytic, enantioselective ring-opening meso epoxides is described (see scheme). Included first demonstration that appropriate modifications beneath plane pyridine N-oxide can serve as a powerful means for tuning catalyst enantioselectivity. Detailed facts importance specialist readers are published "Supporting...

Helical chiral 2-aminopyridinium ions were designed as a significantly more acidic (active) dual hydrogen-bonding catalyst than commonly used (thio)urea-based systems. The helicene framework was specifically utilized to position an inherently barrier on the side of catalyst. reactivity and enantioselectivity successfully demonstrated in additions 4,7-dihydroindoles nitroalkenes (0.5-2 mol % loadings, up 98:2 er).

Highly active and selective: A supported Ru5PtSn nanoparticle cluster (the picture shows an axial projection of a tomogram), prepared from the carbonyl [PtRu5(CO)15(μ-SnPh2)(μ6-C)], is excellent catalyst in single-step hydrogenation dimethyl terephthalate to cyclohexanedimethanol under mild conditions (100 °C, 20 bar H2).

A highly enantioselective synthesis of homopropargylic alcohols is achieved by using the new helical chiral 2,2′-bipyridine N-monoxide catalyst and allenyltrichlorosilane. This method can be further extended to enantio- regioselective propargylation N-acylhydrazones.

In this study we have explored the potential of thiourea (TU) as a template to preorient stilbazoles and bispyridylethylenes (azastilbenes) in crystalline state. TU is able eleven azastilbenes toward dimerization While cocrystals these olefins photodimerized single dimer expected based on crystal packing, pure crystals either were nonreactive or gave mixture dimers. The differential photobehavior highlights importance templating photoreactive orientation X-ray crystallographic photochemical...

Six equivalents of N,N′-bis(4-aminobenzyl)urea, 12 2-formylpyridine and four FeSO4 or NiSO4 undergo subcomponent self-assembly in aqueous solution to form tetrahedral cages around a single, encapsulated sulfate anion.

Polynuclear metal carbonyl complexes have a range of applications in chemical research: for example, they can serve as surface models to probe features heterogeneous catalysis and perform novel transformations organic molecules solutions. Mixed demonstrate bimetallic cooperativity synergism also precursors multimetallic catalysts that superior activities selectivities. This Account describes the results our recent comprehensive study chemistry mixed cluster containing sterically encumbered...

Self-assembling nanoparticles of amphiphilic polymers can transport hydrophobic molecules across hydrophilic media and, as a result, be valuable delivery vehicles for diversity biomedical applications. Strategies to monitor their dynamics noninvasively and in real time are, therefore, essential investigate translocation within soft matrices possibly, rationalize the mechanisms responsible diffusion biological media. In this context, we designed molecular guests with photoactivatable...

Tin(n)y catalysts: Bimetallic RuSn supported nanoparticle catalysts (see picture; Ru green, Sn blue, O red), prepared from the carbonyl-cluster precursors [Ru4(μ4-SnPh)2(μ-SnPh2)4−x(CO)12−x] (x=0, 2, 3, 4) are shown to be active for highly selective hydrogenation of 1,5,9-cyclododecatriene cyclododecene under mild conditions.

There has been a renewed interest in the chemistry of hydrogen as result ever-increasing global demands for energy. Recent studies have revealed new electronically unsaturated polynuclear metal complexes containing bulky ligands that exhibit variety reactions with hydrogen, including facile addition and elimination under mild conditions. Materials molecules can reversibly absorb large quantities are very attractive storage hydrogenation catalysis. This Minireview summarizes recent...

The catalytic performance of cluster-derived PtFe/SiO(2) bimetallic catalysts for the oxidation CO has been examined in absence and presence H(2) (PROX) compared to that Pt/SiO(2). PtFe(2)/SiO(2) Pt(5)Fe(2)/SiO(2) samples were prepared from PtFe(2)(COD)(CO)(8) Pt(5)Fe(2)(COD)(2)(CO)(12) organometallic cluster precursors, respectively. FTIR data indicate both clusters can be deposited intact on SiO(2) support. remained weakly bonded surface could extracted with CH(2)Cl(2) without any...

Minute stoichiometric bimetallic clusters rich in tin (PtSn 2, RhSn and RuSn 2) are powerful selective hydrogenation catalysts: these "molecular metallic" entities, supported on mesoporous silica characterized by aberration-corrected electron microscopy, yield high percentages of cyclododecene (CDE) at fractional conversions ranging from 0.45 to 0.70 the parent cyclododecatriene (CDT) modest temperatures under solvent-free conditions.

Spiralförmige Katalysatoren: Die Synthese von 1-Azahelicenen im Gramm-Maßstab, die Charakterisierung der Struktur zugehörigen N-Oxide und Anwendung dieser neuen Katalysatorfamilie auf katalytische enantioselektive Ringöffnung meso-Epoxiden werden beschrieben (siehe Schema). Durch geeignete Strukturmodifikationen unterhalb Ebene des Pyridin-N-oxids lässt sich Enantioselektivität Katalysatoren effizient einstellen. Detailed facts of importance to specialist readers are published as "Supporting...

When anchored on a high-area, siliceous supports, nanoparticle catalysts, consisting of two or three different metals, but totaling no more than twenty atoms in all, exhibit exceptional activities and selectivities solvent-free, one-step hydrogenation reactions at low temperatures (< 420 K) much lower pressures (e.g. 30 bar) those required current industrial manufacture. The selective hydrogenations illustrated here are the conversion (a) cyclododecatriene (CDT) to cyclododecene (CD) (b)...

The reactivity of a number two-coordinate [Pd(L)(L')] (L = N-heterocyclic carbene (NHC) and L' NHC or PR(3)) complexes with O(2) has been examined. Stopped-flow kinetic studies show that binding to [Pd(IPr)(P(p-tolyl)(3))] form cis-[Pd(IPr)(P(p-tolyl)(3))(η(2)-O(2))] occurs in rapid, second-order process. enthalpy the Pd(0) center determined by solution calorimetry be -26.2(1.9) kcal/mol. Extension this work bis-NHC complex [Pd(IPr)(2)], however, did not lead formation expected diamagnetic...

The reactions of Rh4(CO)12 and Ir4(CO)12 with Ph3SnH have yielded the new Rh−Sn Ir−Sn cluster complexes M3(CO)6(μ-SnPh2)3(SnPh3)3, 1 (M = Rh) 2 Ir). Both compounds contain triangular M3 clusters three bridging SnPh2 terminal SnPh3 ligands. M−M bonds are unusually long. Molecular orbital calculations indicate that this is due to importance M−Sn bonding weak direct interactions. Reaction at reflux in 1,2-dichlorobenzene solvent complex Rh3(CO)3(SnPh3)3(μ-SnPh2)3(μ3-SnPh)2, 3, which contains...

The bis-phosphine compounds M(PBut3)2, M = Pd and Pt, readily eliminate one PBut3 ligand transfer MPBut3 groups to the ruthenium-ruthenium bonds in Ru3(CO)12, Ru6(CO)17(micro6-C), Ru6(CO)14(eta6-C6H6)(micro6-C) without displacement of any ligands on ruthenium complexes. new compounds, Ru3(CO)12[Pd(PBut3)]3, 10, Ru6(CO)17(micro6-C)[Pd(PBut3)]2, 11, Ru6(CO)17(micro6-C)[Pt(PBut3)]n, n 1 (12), 2 (13), Ru6(CO)14(eta6-C6H6)(micro6-C)[Pd(PBut3)]n, (15), (16), have been prepared structurally...

Supramolecular complexation behavior of cucurbiturils with paramagnetic nitroxide spin probes was examined by 1H NMR, X-ray diffraction studies crystals, computation, and EPR. Both cucurbit[7]uril (CB7) cucurbit[8]uril (CB8) form a 1:1 complex 4-(N,N,N-trimethylammonium)-2,2,6,6-tetramethylpiperidinyl-N-oxy bromide (CAT1). The structure the in solid state inferred gas phase computation (B3LYP/6-31G(d)). Whereas ESI-MS data provided evidence for existence solution, indirect obtained through...

Charge-transfer (CT) complexes composed of a π-electron-poor naphthalene diimide (NDI) derivative combined with series π-electron-rich donors were investigated. Solutions the CT are nonemissive; however, solid-state and aqueous suspensions display emission that is dependent on energy HOMO electron donor. Crystallographic analysis pyrene-NDI complex reveals columnar packing high degree frontier molecular orbital (FMO) overlap likely contributes to observed optical properties. The fluorescent...

The binding interactions between two paramagnetic cobaltocenium guests and the hosts cucurbit[7]uril (CB7) cucurbit[8]uril (CB8) were investigated using a combination of electronic absorption, NMR, electron resonance (EPR) spectroscopies, mass spectrometry, X-ray crystallography. Guest 1, (4-amido-2,2,6,6-tetramethylpiperidine-1-oxyl)cobaltocenium, forms very stable inclusion complexes with CB7 CB8. However, interacts 1 by including organometallic unit, while CB8 engulfs TEMPO residue....

Thermodynamic, kinetic, and computational studies are reported for oxygen atom transfer (OAT) to the complex V(N[t-Bu]Ar)3 (Ar = 3,5-C6H3Me2, 1) from compounds containing N-O bonds with a range of BDEs spanning nearly 100 kcal mol(-1): PhNO (108) > SIPr/MesCNO (75) PyO (63) IPr/N2O (62) MesCNO (53) N2O (40) dbabhNO (10) (Mes mesityl; SIPr 1,3-bis(diisopropyl)phenylimidazolin-2-ylidene; Py pyridine; IPr 1,3-bis(diisopropyl)phenylimidazol-2-ylidene; dbabh...

Chelation of the boron center borondipyrromethene (BODIPY) platform by a catecholate ligand results in effective fluorescence suppression. Electron transfer from chelating unit to adjacent chromophore upon excitation is responsible for quenching. Under influence photoacid generator, chelator can be exchanged with pair methoxide ligands. This photoinduced transformation prevents electron and efficiently activates BODIPY chromophore.

Proton transfer from a photoacid generator to halochromic molecular switch within polymer film permits the imprinting of fluorescent patterns under influence optical stimulations.

A mechanism to photoactivate far-red/near-infrared fluorescence with infinite contrast and under mild visible illumination was designed around the photophysical properties of borondipyrromethene (BODIPY) dyes photochemical behavior oxazine heterocycles. Specifically, photoinduced irreversible cleavage an ring a laser line at 405 nm extends electronic conjugation BODIPY chromophore over 3H-indole auxochrome 2-(4-methoxyphenyl)ethenyl substituent in position 5. This structural transformation...