A sensitive Ag-mediated magnetic relaxation and colorimetry dual-mode sensing platform.

To address the relatively low sensitivity of current redox reagent-mediated magnetic relaxation sensing methods, we present a novel Ag-mediated magnetic sensing platform that enhances the sensitivity by three orders of magnitude. The new sensing platform is based on Ag-catalyzed oxidation of Mn to KMnO, accompanied by a distinct color change, which facilitates colorimetric detection. In the case of insufficient Ag ions, MnO is an additional oxidation product and the KMnO/MnO ratio is dependent on the concentration of Ag.

A facile and sensitive magnetic relaxation sensing strategy based on the conversion of Fe ions to Prussian blue precipitates for the detection of alkaline phosphatase and ascorbic acid oxidase.

Herein, a novel magnetic relaxation sensing strategy based on the change in Fe content has been proposed by utilizing the conversion of Fe ions to Prussian blue (PB) precipitates. Compared with the common detection approach based on the valence state change of Fe ions, our strategy can cause a larger change in the relaxation time of water protons and higher detection sensitivity since PB precipitate can induce a larger change in the Fe ion concentration and has a weaker effect on the relaxation process of water protons relative to Fe ions. Then, we employ alkaline phosphatase (ALP) as a model target to verify the feasibility and detection performance of the as-proposed strategy.

Excited-State Dynamics of Crossing-Controlled Energy Transfer in Europium Complexes.

Photosensitized energy transfer (EnT) phenomena occur frequently in a variety of photophysical and photochemical processes and have traditionally been treated with the donor-acceptor distance-dependent Förster and Dexter models. However, incorrect arguments and formulae were employed by ignoring energy resonance conditions and the selection rules of the state-to-state transition in special cases, especially for the sensitive intramolecular EnT of lanthanide complexes. Herein, we proposed an innovative model of energy-degeneracy-crossing-controlled EnT, which can be experimentally confirmed by time-resolved two-dimensional photoluminescence measurements.

Effect of the Transition Metal Ions on the Single-Molecule Magnet Properties in a Family of Air-Stable 3d-4f Ion-Pair Compounds with Pentagonal Bipyramidal Ln(III) Ions.

Single-molecule magnets (SMMs) are expected to be promising candidates for the applications of high-density information storage materials and quantum information processing. Lanthanide SMMs have attracted considerable interest in recent years due to their excellent performance. It has always been interesting but not straightforward to study the relaxation and blocking mechanisms by embedding 3d ions into 4f SMMs.

The comparative studies on the magnetic relaxation behaviour of the axially-elongated pentagonal-bipyramidal dysprosium and erbium ions in similar one-dimensional chain structures.

A family of cyano-bridged 3d-4f 1D chain compounds, {RE[TM(CN)6(2-PNO)5]}·(H2O)4 {RE = YIII, TM = [FeIII]LS (1); RE = DyIII, TM = CoIII (3); RE = ErIII, TM = [FeIII]LS (4), CoIII (5); 2-PNO = 2-picoline-N-oxide} and {RE[TM(CN)6(2-PNO)5]} {RE = DyIII, TM = [FeIII]LS (2)}, were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that compounds 1 and 3-5 are isostructural, while compound 2 has a similar 1D chain structure with a different chain to chain arrangement. An axially-elongated pentagonal bipyramidal (D5h) coordination geometry is formed with five 2-PNO ligands in the equatorial plane and two [TM(CN)6]3- on the apical sites around the rare earth ions in these compounds.

Enhancing the magnetic performance of pyrazine-N-oxide bridged dysprosium chains through controlled variation of ligand coordination modes.

While assembling superparamagnetic units in a controlled manner is crucial for future applications of molecular nanomagnets, optimizing their magnetic properties while achieving directional assembly of these units still remains a formidable challenge. Herein, we demonstrate how the assembly of two dysprosium chain complexes, namely, [Dy(L)Cl(CHOH)]·nCHOH (1) and [Dy(L)Cl(DMF)] (2) (HL = N'-(5-bromo-2-hydroxybenzylidene)pyrazine-N-oxide-carbohydrazide), can be successfully manipulated using an appropriate bridging ligand design. Both complexes contain similar dimeric units bridged by two alkoxido oxygens from an L ligand, but extended by its pyrazine-N-oxide group exhibiting two distinct coordination modes, namely, single and double pyrazine-N-oxide bridges, respectively.

The construction of dynamic dysprosium-carboxylate ribbons by utilizing the hybrid-ligand conception.

By utilizing the hybrid-ligand conception, three novel dysprosium complexes Dy(2-py-4-pmc)(L)(H2O) (H2-py-4-pmc = 2-(2-pyridyl)pyrimidine-4-carboxylic acid; L = fumarate (fum, 1), succinate (suc, 2), or pimelate (pim, 3)) have been successfully synthesized. Structural analysis reveals that the dicarboxylate ligands connect 2-py-4-pmc--protected Dy3+ to form one-dimensional molecular ribbons. Magnetic measurements indicate that the three complexes exhibit typical slow magnetic relaxation under a zero dc field with effective reversal barriers Ueff of 180 K, 145 K and 137 K for 1-3, respectively, which is mainly attributed to the strong Ising anisotropy of dysprosium ions induced by the appropriate arrangement of carboxylate groups.

Dy@CN: a new member of dimetalloazafullerenes with strong single molecular magnetism.

Enhancing the exchange interaction between magnetic ions is a long-term target in molecular magnetism. Endohedral metallofullerenes (EMFs) provide a possibility for achieving such a goal by imprisoning multiple magnetic centers inside the confined inner space of a fullerene cage. Here, we report a new member of dimetallic azafullerene Dy2@C79N via crystallographic determination for the first time.

The differential magnetic relaxation behaviours of slightly distorted triangular dodecahedral dysprosium analogues in a type of cyano-bridged 3d-4f zig-zag chain compounds.

A class of cyano-bridged 3d-4f zig-zag chain compounds, {RE[TM(CN)] (PNO)(HO)}·(HO) {RE = Y, TM = [Fe] (1); RE = Dy, TM = [Fe] (2), Co (3)}, have been synthesized and characterized by single-crystal X-ray diffraction. The rare earth ions in these compounds are situated in a slightly distorted triangular dodecahedral (D) coordination environment. The magnetic properties of compounds 1-3 have been comparatively studied in detail.

Experimental Determination of Magnetic Anisotropy in Exchange-Bias Dysprosium Metallocene Single-Molecule Magnets.

We investigate a family of dinuclear dysprosium metallocene single-molecule magnets (SMMs) bridged by methyl and halogen groups [Cp' Dy(μ-X)] (Cp'=cyclopentadienyltrimethylsilane anion; 1: X=CH ; 2: X=Cl ; 3: X=Br ; 4: X=I ). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.

Synthesis of flavonoids nitrogen mustard derivatives and study on their antitumor activity in vitro.

Several novel flavonoids nitrogen mustard derivatives were synthesized and evaluated for antiproliferative activity against seven human cancer cell lines (HeLa, A549, HepG2, MCF7, SH-SY5Y, PC-3, DU145) by the MTT assay in vitro. The resulting IC showed that most compounds exhibited better inhibitory activity against seven cell lines. IC values of some compounds were lower than well-known melphalan.

Lanthanide-Organic Frameworks Constructed from 2,7-Naphthalenedisulfonate and 1-Imidazo[4,5-][1,10]-phenanthroline: Synthesis, Structure, and Luminescence with Near-Visible Light Excitation and Magnetic Properties.

New Ln-metal-organic frameworks (Ln-MOFs), {[Ln(2,7-NDS)(IP)(OH)(HO)]·HO} [Ln = Sm , Eu , Gd , Tb , Dy , = 0.5-0; 2,7-NDS = 2,7-naphthalenedisulfonate, and IP = 1-imidazo[4,5-][1,10]-phenanthroline) were obtained by the hydrothermal method. The Ln-MOFs feature one-dimensional double chain structures.

Dysprosium complexes bearing unsupported Dy-Ge/Sn metal-metal bonds as single-ion magnets.

Two dysprosium complexes bearing unsupported Dy-Ge/Sn metal-metal bonds are reported here, wherein the Dy-Ge and Dy-Sn bonds both contain relatively large covalency. The complexes exhibit slow relaxation of magnetization at zero field with energy barriers of 485 and 620 K, respectively, and the blocking temperature of 6 K.

Publisher Correction: Proton mediated spin state transition of cobalt heme analogs.

In the original version of this Article, the four structural depictions of orbital distributions were inadvertently omitted from Figure 5. This has now been corrected in both the HTML and PDF versions of the Article.

Proton mediated spin state transition of cobalt heme analogs.

The spin state transition from low spin to high spin upon substrate addition is one of the key steps in cytochrome P450 catalysis. External perturbations such as pH and hydrogen bonding can also trigger the spin state transition of hemes through deprotonated histidine (e.g.

Bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato]terbium Double-Decker Single-Ion Magnets.

For the purpose of further exploring the effect of nonperipherally attached substituents on single-ion magnet (SIMs) performance, tetrasubstituted bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato]terbium double-deckers, in both the reduced form TbH[Pc(α-OCH)] (1) and the neutral form Tb[Pc(α-OCH)] (2), were prepared. Single-crystal X-ray diffraction analysis for 2 unambiguously demonstrates the pinwheellike molecular structure with C symmetry. Magnetic investigations of the two bis(phthalocyaninato)terbium double-deckers reveal their characteristic SIM nature.

Elucidation of the two-step relaxation processes of a tetranuclear dysprosium molecular nanomagnet through magnetic dilution.

A new centrosymmetric tetranuclear aggregate [Dy4(L)2(OAc)8(CH3OH)2] (1) was assembled using a unique symmetrical Schiff base ligand 1,5-bis(salicylidene)-carbohydrazide (H2L). Magnetic studies reveal ferromagnetic interactions between dysprosium ions and two obvious relaxation processes under zero dc field with effective energy barriers Ueff of 38 K and 223 K, the highest among the reported tetranuclear dysprosium molecular nanomagnets. To obtain further evidence on the origination of the slow magnetic relaxation, a diamagnetic yttrium analogue [Y4(L)2(OAc)8(CH3OH)2] (2) and a diluted sample [(Dy0.

A neutral auxiliary ligand enhanced dysprosium(iii) single molecule magnet.

An approximately equatorial three-coordinated dysprosium(iii) complex DyL2[N(SiMe3)2] (L = bis(2-(2,5-dimethyl-1H-pyrrol-1-yl)ethyl)amine) with an additional neutral auxiliary pyrrole ligand was synthesised and structurally characterized. The magnetic property measurement shows that it is an equatorial charge distributed field-induced single-molecule magnet. Ab initio calculations reveal that the neutral pyrrole ligand plays an important role in stabilizing the ground doublet and thus enhancing the magnetic anisotropy.

Fabricating Bis(phthalocyaninato) Terbium SIM into Tetrakis(phthalocyaninato) Terbium SMM with Enhanced Performance through Sodium Coordination.

The non-peripherally substituted 1,4,8,11,15,18,22,25-octa(butoxy)-phthalocyanine-involved unsymmetrical heteroleptic bis(phthalocyaninato) terbium double-decker, Tb(Pc){H[Pc(α-OC H ) ]} (Pc=unsubstituted phthalocyanine) (1), was revealed to exhibit typical single ion magnet (SIM) behavior with effective energy barrier, 180 K (125 cm ), and blocking temperature, 2 K, due to the severe deviation of the terbium coordination polyhedron from square-antiprismatic geometry. Fabrication of this double-decker compound into the novel tetrakis(phthalocyaninato) terbium pseudo-quadruple-decker Na {Tb(Pc)[Pc(α-OC H ) ]} (2) single molecule magnet (SMM) not only optimizes the coordination polyhedron of terbium ion towards the square-antiprismatic geometry and intensifies the coordination field strength, but more importantly significantly enhances the molecular magnetic anisotropy in the unsymmetrical bis(phthalocyaninato) double-decker unit, along with the change of the counter cation from H of 1 to Na of 2, leading to an significantly enhanced magnetic behavior with spin-reversal energy barrier, 528 K (367 cm ), and blocking temperature, 25 K. The present result is surely helpful towards developing novel tetrapyrrole lanthanide SMMs through rational design and self-assembly from bis(tetrapyrrole) lanthanide single ion magnet (SIM) building block.

Correction: Isostructural lanthanide-based metal-organic frameworks: structure, photoluminescence and magnetic properties.

Correction for 'Isostructural lanthanide-based metal-organic frameworks: structure, photoluminescence and magnetic properties' by Li-Lin Luo et al., Dalton Trans., 2018, 47, 925-934.

Isostructural lanthanide-based metal-organic frameworks: structure, photoluminescence and magnetic properties.

A series of the anhydrous lanthanide-based metal-organic frameworks (Ln-MOFs) were successfully synthesized under hydrothermal conditions of Ln(iii) ions with 3,4'-oxybis(benzoate) (3,4'-oba), oxalate (ox) and 1,10-phenanthroline (phen). Structural analyses revealed that they are isostructural 3D open-frameworks with the formula of [Ln(3,4'-oba) (phen)(ox)] (Ln = Sm for 1, Eu for 2, Gd for 3, Tb for 4, and Dy for 5) and the topology of {3·4·5·6}. Within the 3D structure, the [LnON] units are bridged by ox to form [Lnox] dimers and then are further connected by 3,4'-oba ligands.

Modulating Slow Magnetic Relaxation of Dysprosium Compounds through the Position of Coordinating Nitrate Group.

A chain complex [Dy(L)(NO)CHOH] (1) and a dinuclear compound [Dy(L)(NO)(CHOH)]·2CHOH (2) were synthesized by the assembly of a novel pyridine-N-oxide-containing ligand with dysprosium nitrate under different reaction temperatures, where two coordinating nitrates are located in para or ortho position with respect to each other around dysprosium ions. Magnetic studies indicate that the chain complex with two para-coordinating nitrates shows fast quantum tunnelling of the magnetization under zero direct-current field, while the dinuclear complex with two ortho-coordinating nitrates exhibits a thermal-activated process with an effective energy barrier of 51 K. Theoretical and magneto-structural correlation studies indicate that position change of coordinating nitrates can significantly modulate the crystal field around dysprosium ion and further lead to their different relaxation behaviors.

Chiral six-coordinate Dy(iii) and Tb(iii) complexes of an achiral ligand: structure, fluorescence, and magnetism.

Two new chiral six-coordinate lanthanide complexes (1 for Dy and 2 for Tb) have been synthesized using the achiral flexible ligand HL (2,2'-[1,2-ethanediylbis[(methylimino)methylene]]bis[4,5-dimethylphenol]). Both complexes crystallize in the chiral P1 group space, and the enantiomers [Zn(L)Cl]Dy·MeOH·0.5HO (Λ-1), [Zn(L)Cl]Dy·1.

Three bilindione isomers: synthesis, characterization and reactivity of biliverdin analogs.

Linear tetrapyrrole is the core structure of light-sensitive native cofactors such as phycocyanobilin, phytochromobilin and bile pigments, which attracts increasing attention in biomimetic chemistry, photochemistry and coordination chemistry. To decipher the relationship between structures and functions, in this work, we firstly reported the synthesis, isolation and characterization of three bilindione isomers (ZZZ, syn, syn, syn 1, EZE, syn, syn, anti 2 and EZE, anti, syn, anti 3) bearing meso-pentafluorophenyl groups. The structures were confirmed by X-ray diffraction and 2-D NMR spectroscopes.

Bioinspired Orientation of β-Substituents on Porphyrin Antenna Ligands Switches Ytterbium(III) NIR Emission with Thermosensitivity.

"Configurational isomerism" is an important approach found in naturally occurring chlorophylls to modulate light harvesting function without significant structural changes; however, this feature has been seldom applied in design of antenna ligands for lanthanide (Ln) sensitization. In this work, we introduced a bioinspired approach by orientation of β-dilactone moieties on porphyrinates, namely cis-/trans-porphodilactones, to modulate the energy transfer process from the lowest triplet excited state of the ligand (T) to the emitting level of ytterbium(III) (F, Yb*). Interestingly, near-infrared (NIR) emission of Yb(III) could be switched "on" by the cis-porphodilactone ligand, while the trans-isomer renders Yb(III) emission "off" and the ratio of quantum yields is ∼8.