Corrigendum to: Physicochemical insights of irradiation-enhanced hydroxyl radical generation from ZnO nanoparticles.

[This corrects the article DOI: 10.1039/c5tx00384a.].

Initializing 2 Pure 14-Qubit Entangled Nuclear Spin States in a Hyperpolarized Molecular Solid.

Quantum entanglement has been realized on a variety of physical platforms such as quantum dots, trapped atomic ions, and superconductors. Here we introduce specific molecular solids as promising alternative platforms. Our model system is triplet pentacene in a host single crystal at level anticrossing (LAC) conditions.

A new series of heteronuclear metal strings, MRhRh(dpa)Cl and MRhRhM(dpa)X, from the reactions of Rh(dpa) with metal ions of group 7 to group 12.

We report the syntheses, structures, magnetic and electrochemical properties of MRhRh metal cores helically wrapped by four dpa- (2,2'-dipyridylamide) ligands. We successfully synthesized the precursor Rh2(dpa)4 (1) in high yield and characterized its structure including its oxidized form (1+) which facilitated the syntheses of this series of metal springs. By the reactions of (1) and the metal ions of group 7 to group 12 (M = Mn(2), Fe(3), Co(4), Ni(5), Cu(6), Pd(8), Pt(9), Ru(10), Ir(11) and Rh(12)), ten MRh2(dpa)4Cl2 complexes were successfully isolated.

Giant Zeeman Splitting for Monolayer Nanosheets at Room Temperature.

Giant Zeeman splitting and zero-field splitting (ZFS) are observed in 2D nanosheets that have monolayers of atomic thickness. In this study, single-crystalline CdSe(ethylenediamine) and Mn-doped nanosheets are synthesized via a solvothermal process. Tunable amounts of Mn(0.

Structure and magnetic properties of a novel heteroheptanuclear metal string complex [NiRuNi(μ-teptra)(NCS)](PF).

We report the synthesis of a novel heteroheptanuclear metal string complex (HMSC) [NiRuNi(μ-teptra)(NCS)](PF) 1 supported by tetra-pyridyl-tri-amine (Hteptra) ligands. We employed X-ray diffraction and other spectroscopic techniques to characterize the complex. The observed remarkably short Ru-Ru distance of 2.

Structures and paramagnetism of five heterometallic pentanuclear metal strings containing as many as four different metals: NiPtCoPd(tpda)Cl.

Five heterometallic pentanuclear metal strings were prepared by stepwise synthesis from two to three and four kinds of metals aligned in one chain. In particular, NiPtCo2Pd(tpda)4Cl2 (5) possesses four different metals, and the SQUID measurement shows that Ni2+ is the only magnetically active center. Besides, the shortest Co(ii)-Co(ii) single bond (2.

Manganese Telluride Carbonyl Complexes: Facile Syntheses and Exotic Properties-Reversible Transformations, Hydrogen Generation, Paramagnetic, and Semiconducting Properties.

A novel family of five Mn-Te-CO complexes was prepared via facile syntheses: mono spirocyclic [MnTe(CO)] (), four-membered MnTe ring-type [MnTe(CO)] (), hydride-containing square pyramidal [HMnTe(CO)] (), and dumbbell-shaped [MnTe(CO)] () and [MnTe(CO)] (). Electron-precise complexes and exhibit unusual paramagnetism arising from two types of Mn atoms in different oxidation states, as determined by X-ray photoelectron spectroscopy, electron paramagnetic resonance, and density functional theory (DFT) calculations. The structural transformations from small-sized MnTe and MnTe to the largest MnTe were controllable, the off/on magnetic-switched transformation between HMnTe and was reversible, and the magnetic transformation between MnTe and was observed.

The synthesis and magnetic properties of a linear mixed-valence [Ni] in an anthyridine tri-nickel complex.

A novel trinuclear complex [Ni(μ-dbay)Cl]I (1) with a mixed-valence state was prepared by reacting the tridentate ligand 1,13,14-triaza-dibenz[a,j]anthracene (dibenzanthyridine = dbay) with anhydrous NiCl and sodium tetraphenylborate. The title compound provides the first example of a trinuclear nickel-anthyridine-based string complex in which the metal framework of complex 1 consists of Ni-Ni-Ni. X-ray crystallography, magnetic susceptibility and detailed EPR measurements were performed to characterize the structure and magnetic properties of this unique complex.

Ligand effects on the structure, mixed-valence sites and magnetic properties of novel pentanickel string complexes.

We report the syntheses, characterization, electronic structures and magnetic properties of four redox pairs of novel nickel-extended metal-atom chain (EMAC) complexes containing pyridine-, naphthyridine- and sulfonyl-containing ligands (HTspnda and HMspnda) (1-2 and 5-6). We further study the corresponding phenyl-substituted ligands (HTsphpnda and HMsphpnda) (3-4 and 7-8) to examine the details of ligand effects. The X-ray structure of one-electron-reduced [Ni] complexes shows shorter Ni-Ni bond distances (2.

Destabilizing Character of a π-Conjugated Boron Center in Bisphenol Radicals.

Although boron-containing radicals are promising materials for molecular electronic devices, the electronic effect of the σ-donating yet π-accepting boron center on the stability of open-shell species has been less discussed. In this work, the role of a tricoordinate boron center in π-conjugated radicals was explored through electron paramagnetic resonance measurement of several boron-linked bisphenol radicals and diradicals. Replacing the bridging methine fragment of a neutral Galvinoxyl radical with an arylboryl group led to the corresponding boron-linked radical anion that requires excessive steric protection at the boron center to be persistent in solution.

1,2-Migration of N-Diarylboryl Imidazol-2-ylidene through Intermolecular Radical Process.

1,2-Boryl migration of N-boryl N-heterocyclic carbene to 2-boryl imidazole is proposed to proceed through generation and recombination of two radical intermediates, namely, a neutral diarylboron radical and a N-heterocyclic carbene radical. Crossover experiments suggest that these two radical species are stable enough to escape solvent cages and recombine intermolecularly. The presence of radical intermediates is further supported by spin trapping experiments.

A Structurally Characterized Nonheme Cobalt-Hydroperoxo Complex Derived from Its Superoxo Intermediate via Hydrogen Atom Abstraction.

Bubbling O into a THF solution of Co(BDPP) (1) at -90 °C generates an O adduct, Co(BDPP)(O) (3). The resonance Raman and EPR investigations reveal that 3 contains a low spin cobalt(III) ion bound to a superoxo ligand. Significantly, at -90 °C, 3 can react with 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPOH) to form a structurally characterized cobalt(III)-hydroperoxo complex, Co(BDPP)(OOH) (4) and TEMPO.

Physicochemical insights of irradiation-enhanced hydroxyl radical generation from ZnO nanoparticles.

The widespread use of zinc oxide nanoparticles (ZnO NPs) has raised environmental and human health concerns owing to their significant cytotoxicity. Although their cytotoxic effects have been associated with reactive oxygen species (ROS), the physicochemical mechanism underlying this phenomenon remains poorly understood. In this study, the physicochemical properties of ZnO NPs were systematically investigated in relation to their effect on ROS generation.

Redox chemistry of a hydroxyphenyl-substituted borane.

Chemical reduction of a hydroxyphenyl-substituted borane triggers a sequential electron- and intramolecular hydrogen-atom-transfer process to afford a hydridoborate phenoxide dianion. On the other hand, hydrogen-atom abstraction of the borane leads to the isolation of a neutral borylated phenoxyl radical, which can be transformed to the corresponding benzoquinone borataalkene derivative by reduction with cobaltocene.

Protection of HeLa cells against ROS stress by CuZnSOD mimic system.

A new copper zinc complex (CZpbi), [(bipyridinyl)Cu-μ-pbi-Zn(pbi)](ClO), pbi = 2-(2-pyridyl)-benzimidazole, was synthesized to mimic copper zinc superoxide dismutase (CuZnSOD). CZpbi was then encapsulated onto a dye (fluorescein isothiocyanate, FITC) functionalized mesoporous silica nanoparticles (MSN) where MSN serves as a nanofactory platform for delivering the catalytic action of the center copper complex. We examined the inhibition of oxidative damage of HeLa cells in the presence of paraquat (PQ, 1,1'-dimethyl-4,4'-bipyridylium dichloride, an oxidative stressor).

Roles of free radicals in type 1 phototherapeutic agents: aromatic amines, sulfenamides, and sulfenates.

Detailed analyses of the electron spin resonance (ESR) spectra, cell viability, and DNA degradation studies are presented for the photolyzed Type I phototherapeutic agents: aromatic amines, sulfenamides, and sulfenates. The ESR studies provided evidence that copious free radicals can be generated from these N-H, N-S, and S-O containing compounds upon photoirradiation with UV/visible light. The analyses of spectral data allowed us to identify the free radical species.

Strong metal-support interactions between gold nanoparticles and ZnO nanorods in CO oxidation.

The catalytic performances of supported gold nanoparticles depend critically on the nature of support. Here, we report the first evidence of strong metal-support interactions (SMSI) between gold nanoparticles and ZnO nanorods based on results of structural and spectroscopic characterization. The catalyst shows encapsulation of gold nanoparticles by ZnO and the electron transfer between gold and the support.

Type 1 Phototherapeutic Agents. 2. Cancer Cell Viability and ESR Studies of Tricyclic Diarylamines.

Type 1 phototherapeutic agents based on diarylamines were assessed for free radical generation and evaluated in vitro for cell death efficacy in the U937 leukemia cancer cell line. All of the compounds were found to produce copious free radicals upon photoexcitation with UV-A and/or UV-B light, as determined by electron spin resonance (ESR) spectroscopy. Among the diarylamines, the most potent compounds were acridan (4) and 9-phenylacridan (5), with IC50 values of 0.

Type 1 phototherapeutic agents, part I: preparation and cancer cell viability studies of novel photolabile sulfenamides.

Novel type 1 phototherapeutic agents based on compounds containing S-N bonds (sulfenamides) were synthesized, assessed for free radical generation, and evaluated in vitro for cell death efficacy in four cancer cell lines (U937, HTC11, KB, and HT29). All of the compounds were found to produce copious free radicals upon photoexcitation with UV-A and/or UV-B light, as determined by electron spin resonance spectroscopy. Among the sulfenamides, the most potent compounds were derived from dibenzazepine 7b and dihydroacridine 8b as determined in all of the four cancer cell lines.

Quantum oscillations and polarization of nuclear spins in photoexcited triplet states.

The unique physical properties of photoexcited triplet states have been explored in numerous spectroscopic studies employing electron paramagnetic resonance (EPR). So far, however, no quantum interference effects were found in these systems in the presence of a magnetic field. In this study, we report the successful EPR detection of nuclear quantum oscillations in an organic triplet state subject to an external magnetic field.

Pulsed electron nuclear double resonance studies of the photoexcited triplet state of pentacene in p-terphenyl crystals at room temperature.

Pulsed electron nuclear double resonance (ENDOR) using a modified Davies-type [Phys. Lett. 47A, 1 (1974)] sequence is employed to study the hyperfine (HF) structure of the photoexcited triplet state of pentacene dispersed in protonated and deuterated p-terphenyl single crystals.

Dynamics of p-terphenyl crystals at the phase transition temperature: a zero-field EPR study of the photoexcited triplet state of pentacene in p-terphenyl crystals.

Pulsed zero-field electron paramagnetic resonance free induction decay (ZF EPR FID) techniques are employed to study the phase transition of p-terphenyl crystals (Tc = 193 K) by measuring selectively populated photoexcited triplet ZF transitions of dilute pentacene molecules in p-terphenyl single crystals. The sensitivity of ZF spectroscopy to small shifts in local magnetic fields enables the studies of guest-host configuration changes over a wide temperature range. Here we report the observation of guest pentacene (-h(14) and -d(14)) triplet ZF EPR FID spectra that disappear abruptly at Tc and of spectral broadening and shift below Tc.

Characterization and biomimetic study of a hydroxo-bridged dinuclear phenanthroline cupric complex encapsulated in mesoporous silica: models for catechol oxidase.

We report the synthesis and characterization of a hydroxo-bridged dinuclear phenanthroline cupric complex, [(phen)2Cu-OH-Cu(phen)2](ClO4)) (HPC, phen = phenanthroline), dispersed in molecular sieves: MCM-41's and sodium zeolite Y. We employed spectroscopic techniques (FT-IR, UV-visible, EPR, and EXAFS) to characterize and study the catalytic activities of immobilized HPC in the oxidation of 3,5-di-tert-butylcatechol (DTBC) to the corresponding quinone (3,5-di-tert-butylquinone, DTBQ) to mimic the functionality of catechol oxidases. HPC complexes can adsorb only on the outside surface of the Y zeolite due to its smaller pore size.

Enhancing stability and oxidation activity of cytochrome C by immobilization in the nanochannels of mesoporous aluminosilicates.

Hydrothermally stable and structrurally ordered mesoporous and microporous aluminosilicates with different pore sizes have been synthesized to immobilize cytochrome c (cyt c): MAS-9 (pore size 90 A), MCM-48-S (27 A), MCM-41-S (25 A), and Y zeolites (7.4 A). The amount of cyt c adsorption could be increased by the introduction of aluminum into the framework of pure silica materials.

Orientational anisotropic studies by field rotation technique: near zero-field pulsed EPR experiments of pentacene doped in p-terphenyl.

We report a new technique to map the orientational anisotropy of paramagnetic systems without physically changing the crystal orientations in near zero-field (NZF) pulsed EPR experiments. By implementing three sets of orthogonal coils around the sample, we are ble to create a magnetic vector up to 2 mT in any three-dimensional orientation in space. In NZF region, the hyperfine tensor elements are comparable to the electronic Zeeman interaction energy, thus very rich spectral patterns can be obtained by "dialing" in a magnetic field vector without moving the sample.