Reactive Magnesium Nanoparticles to Perform Reactions in Suspension.

Zerovalent magnesium (Mg(0)) nanoparticles are prepared in the liquid phase (THF) by reduction of MgBr2 either with lithium naphthalenide ([LiNaph]) or lithium biphenyl ([LiBP]). [LiBP]-driven reduction results in smaller Mg(0) nanoparticles (10.3±1.7 nm) than [LiNaph]-driven reduction (28.5±4 nm). The as-prepared Mg(0) nanoparticles are monocrystalline (d101=245±5 pm) for both types of reduction. Their reactivity is probed by liquid-phase reaction (THF, toluene) in suspension near room temperature (20-120 °C) with 1-bromoadamantane (AdBr), chlortriphenylsilane (Ph3SiCl), trichlorphenylsilane (PhSiCl3), 9H-carbazole (Hcbz), 7-azaindole (Hai), 1,8-diaminonaphthalene (H4nda) and N,N'-bis(α-pyridyl)-2,6-diaminopyridine (H2tpda) as exemplary starting materials. The reactions result in the formation of 1,1'-biadamantane (1), [MgCl2(thf)2]×Ph6Si2 (2), [Mg9(thf)14Cl18] (3), [Mg(cbz)2(thf)3] (4), [Mg4O(ai)6]×1.5 C7H8 (5), [Mg4(H2nda)4(thf)4] (6) and [Mg3(tpda)3] (7) with 40-80 % yield. 1 and 2 show the reactivity of Mg(0) nanoparticles for C-C and Si-Si coupling reactions with sterically demanding starting materials. 3-7 represent new coordination compounds using sterically demanding N-H-acidic amines as starting materials. The formation of multinuclear Mg2+ complexes with multidentate ligands illustrates the potential of the oxidative approach to obtain novel compounds with Mg(0) nanoparticles in the liquid phase.

Sc, Zr, Hf, and Mn Metal Nanoparticles: Reactive Starting Materials for Synthesis Near Room Temperature.

Zerovalent scandium, zirconium, hafnium, and manganese nanoparticles are prepared by reduction of ScCl3, ZrCl4, HfCl4, and MnCl2 with lithium or sodium naphthalenide in a one-pot, liquid-phase synthesis. Small-sized monocrystalline nanoparticles are obtained with diameters of 2.4 ± 0.2 nm (Sc), 4.0 ± 0.9 nm (Zr), 8.0 ± 3.9 nm (Hf) and 2.4 ± 0.3 nm (Mn). Thereof, Zr(0) and Hf(0) nanoparticles with such size are shown for the first time. To probe the reactivity and reactions of the as-prepared Sc(0), Zr(0), Hf(0), and Mn(0) nanoparticles, they are exemplarily reacted in the liquid phase (e.g., THF, toluene, ionic liquids) with different sterically demanding, monodentate to multidentate ligands, mainly comprising O-H and N-H acidic alcohols and amines. These include isopropanol (HOiPr), 1,1'-bi-2-naphthol (H2binol), N,N'-bis(salicylidene)ethylenediamine (H2salen), 2-mercaptopyridine (2-Hmpy), 2,6-diisopropylaniline (H2dipa), carbazole (Hcz), triphenylphosphane (PPh3), N,N,N',N'-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bipy), N,N'-diphenylformamidine (Hdpfa), N,N'-(2,6-diisopropylphenyl)-2,4-pentanediimine ((dipp)2nacnacH), 2,2'-dipydridylamine (Hdpa), and 2,6-bis(2-benzimidazolyl)pyridine (H2bbp). As a result, 22 new compounds are obtained, which frequently exhibit a metal center coordinated only by the sterically demanding ligand. Options and restrictions for the liquid-phase syntheses of novel coordination compounds using the oxidation of base-metal nanoparticles near room temperature are evaluated.

SMART RHESINs-Superparamagnetic Magnetite Architecture Made of Phenolic Resin Hollow Spheres Coated with Eu(III) Containing Silica Nanoparticles for Future Quantitative Magnetic Particle Imaging Applications.

Magnetic particle imaging (MPI) is a powerful and rapidly growing tomographic imaging technique that allows for the non-invasive visualization of superparamagnetic nanoparticles (NPs) in living matter. Despite its potential for a wide range of applications, the intrinsic quantitative nature of MPI has not been fully exploited in biological environments. In this study, a novel NP architecture that overcomes this limitation by maintaining a virtually unchanged effective relaxation (Brownian plus Néel) even when immobilized is presented. This superparamagnetic magnetite architecture made of phenolic resin hollow spheres coated with Eu(III) containing silica nanoparticles (SMART RHESINs) was synthesized and studied. Magnetic particle spectroscopy (MPS) measurements confirm their suitability for potential MPI applications. Photobleaching studies show an unexpected photodynamic due to the fluorescence emission peak of the europium ion in combination with the phenol formaldehyde resin (PFR). Cell metabolic activity and proliferation behavior are not affected. Colocalization experiments reveal the distinct accumulation of SMART RHESINs near the Golgi apparatus. Overall, SMART RHESINs show superparamagnetic behavior and special luminescent properties without acute cytotoxicity, making them suitable for bimodal imaging probes for medical use like cancer diagnosis and treatment. SMART RHESINs have the potential to enable quantitative MPS and MPI measurements both in mobile and immobilized environments.

Glucocorticoid Nanoparticles Show Full Therapeutic Efficacy in a Mouse Model of Acute Lung Injury and Concomitantly Reduce Adverse Effects.

Glucocorticoids (GCs) are widely used to treat inflammatory disorders such as acute lung injury (ALI). Here, we explored inorganic-organic hybrid nanoparticles (IOH-NPs) as a new delivery vehicle for GCs in a mouse model of ALI. Betamethasone (BMZ) encapsulated into IOH-NPs (BNPs) ameliorated the massive infiltration of neutrophils into the airways with a similar efficacy as the free drug. This was accompanied by a potent inhibition of pulmonary gene expression and secretion of pro-inflammatory mediators, whereas the alveolar-capillary barrier integrity was only restored by BMZ in its traditional form. Experiments with genetically engineered mice identified myeloid cells and alveolar type II (AT II) cells as essential targets of BNPs in ALI therapy, confirming their high cell-type specificity. Consequently, adverse effects were reduced when using IOH-NPs for GC delivery. BNPs did not alter T and B cell numbers in the blood and also prevented the induction of muscle atrophy after three days of treatment. Collectively, our data suggest that IOH-NPs target GCs to myeloid and AT II cells, resulting in full therapeutic efficacy in the treatment of ALI while being associated with reduced adverse effects.

Excited State Dynamics of Alizarin Red S Nanoparticles in Solution.

Alizarin red S is a sulfonated, water-soluble derivative of alizarin. This work presents femtosecond studies of alizarin red S (ARS) nanoparticles in comparison to ARS in aqueous solution and to alizarin in DMSO. The femtosecond studies cover a probing spectral range of 350-750 nm using different excitation wavelengths, taking into account the variation of the absorption spectra with the pH values of the solvent. Stationary absorption spectra show slight differences between solution and nanoparticles. Excitation at 530 nm results in low and noisy responses, therefore, we additionally recorded transient spectra of the nanoparticles at λex = 267 nm. While the results in DMSO are comparable to previous studies in non-aqueous solvents, we report a relatively fast relaxation of 14 ps in [La(OH)2][ARS] nanoparticles in aqueous solution after excitation at 530 nm, which is similar to Na(ARS) solution (19 ps). The dynamics changed with lower pH, but still without significant differences between nanoparticles and solution. We propose [La(OH)2][ARS] nanoparticles as a suitable alternative to dissolved molecules with similar spectroscopic properties, for example, with regard to biomarker applications.

[Sm6O4(cbz)10(thf)6]·2C7H8: A Polynuclear Samarium Oxo Cluster Obtained from Carbazole-Driven Oxidation of Samarium Nanoparticles.

Zerovalent samarium nanoparticles (1.7 ± 0.2 nm in size) are used as the starting material to prepare single crystals of the novel polynuclear samarium oxo cluster [Sm6O4(cbz)10(thf)6]·2C7H8. The reaction is performed by oxidation with carbazole (CbzH) in tetrahydrofuran (THF) at 50 °C with subsequent crystallization in toluene (C7H8). The oxo cluster contains noncharged molecular units with a central Sm6O4 core. Single-crystal structure analysis and infrared spectroscopy confirm the oxidation of CbzH with the formation of (cbz)-. Polynuclear carbazole complexes are generally rare and here prepared using metal nanoparticles as a reactive starting material for the first time. The reaction with CbzH as a sterically demanding ligand exemplarily shows the feasibility of rare-earth-metal nanoparticles for obtaining new compounds with complex composition and structure.

Room-Temperature Synthesis of [BMIm][Sn5O2Cl7] with ∞1(Sn2OCl2) Strands in a Saline [BMIm][SnCl3] Matrix.

The novel tin(II) oxychloride [BMIm][Sn5O2Cl7] (BMIm = 1-butyl-3-methylimidazolium) is obtained by the room-temperature reaction (25 °C) of black SnO and SnCl2 in [BMIm]Cl/SnCl2 as an ionic liquid. The title compound can be described as composed of noncharged, infinite ∞1(Sn2OCl2) strands that are embedded in a saline matrix of [BMIm]+ and [SnCl3]-. The ∞1(Sn2OCl2) strands consist of a backbone of edge-sharing OSn4/2 tetrahedra, which represent one-dimensional (1D) strands cut out of the layer-type structure of SnO. In [BMIm][Sn5O2Cl7], the ∞1(Sn2OCl2) strands, which mimic a 1D semiconductor, are terminated by chlorine atoms, whereas they are interconnected by oxygen atoms in the 2D semiconductor SnO. The view of the noncharged ∞1(Sn2OCl2) strands in a saline [BMIm][SnCl3] matrix is validated by dissolution experiments. Thus, electron microscopy and Raman spectroscopy show a deconstruction of [BMIm][Sn5O2Cl7] single crystals after treatment with chloroform with a dissolution of [BMIm][SnCl3], the formation of SnCl2 needles, and tin oxide as a solid remain.

18-Crown-6 Coordinated Metal Halides with Bright Luminescence and Nonlinear Optical Effects.

The crown-ether coordination compounds ZnX2(18-crown-6), EuX2(18-crown-6) (X: Cl, Br, I), MnI2(18-crown-6), Mn3Cl6(18-crown-6)2, Mn3I6(18-crown-6)2, and Mn2I4(18-crown-6) are obtained by ionic-liquid-based synthesis. Whereas MX2(18-crown-6) (M: Zn, Eu) show conventional structural motives, Mn3Cl6(18-crown-6)2, Mn3I6(18-crown-6)2, and Mn2I4(18-crown-6) exhibit unusual single MnX4 tetrahedra coordinated to the crown-ether complex. Surprisingly, some compounds show outstanding photoluminescence. Thus, rare Zn2+-based luminescence is observed and unexpectedly efficient for ZnI2(18-crown-6) with a quantum yield of 54%. Unprecedented quantum yields are also observed for Mn3I6(18-crown-6)2, EuBr2(18-crown-6), and EuI2(18-crown-6) with values of 98, 72, and 82%, respectively, which can be rationalized based on the specific structural features. Most remarkable, however, is Mn2I4(18-crown-6). Its specific structural features with finite sensitizer-activator couples result in an extremely strong emission with an outstanding quantum yield of 100%. Consistent with its structural features, moreover, anisotropic angle-dependent emission under polarized light and nonlinear optical (NLO) effects occur, including second-harmonic generation (SHG). The title compounds and their optical properties are characterized by single-crystal structure analysis, X-ray powder diffraction, chemical analysis, density functional theory (DFT) calculations, and advanced spectroscopic methods.

Glucocorticoids delivered by inorganic-organic hybrid nanoparticles mitigate acute graft-versus-host disease and sustain graft-versus-leukemia activity.

Glucocorticoids (GCs) are widely used to treat acute graft-versus-host disease (aGvHD) due to their immunosuppressive activity, but they also reduce the beneficial graft-versus-leukemia (GvL) effect of the allogeneic T cells contained in the graft. Here, we tested whether aGvHD therapy could be improved by delivering GCs with the help of inorganic-organic hybrid nanoparticles (IOH-NPs) that preferentially target myeloid cells. IOH-NPs containing the GC betamethasone (BMP-NPs) efficiently reduced morbidity, mortality, and tissue damage in a totally MHC mismatched mouse model of aGvHD. Therapeutic activity was lost in mice lacking the GC receptor (GR) in myeloid cells, confirming the cell type specificity of our approach. BMP-NPs had no relevant systemic activity but suppressed cytokine and chemokine gene expression locally in the small intestine, which presumably explains their mode of action. Most importantly, BMP-NPs delayed the development of an adoptively transferred B cell lymphoma better than the free drug, although the overall incidence was unaffected. Our findings thus suggest that employing IOH-NPs could diminish the risk of relapse associated with GC therapy of aGvHD patients while still allowing to efficiently ameliorate the disease.

Insights of the Structure and Luminescence of Mn2+/Sn2+-Containing Crown-Ether Coordination Compounds.

Crown-ether coordination compounds with Mn2+ and Sn2+ as cations and 12-crown-4, 15-crown-5, and 18-crown-6 as ligands are synthesized. Their luminescence properties and quantum yields are compared and correlated with their structural features. Thus, MnI2(15-crown-5) (1), MnCl2(15-crown-5) (2), [Mn(12-crown-4)2]2[N(Tf)2]2(12-crown-4) (3), Sn3I6(15-crown-5)2 (4), and SnI2(18-crown-6) (5) are obtained by an ionic-liquid-based reaction of MX2 (M: Mn, Sn; X: Cl, I) and the respective crown ether. Whereas 1, 2, and 5 exhibit a centric coordination of Mn2+/Sn2+ by the crown ether, 3 and 4 show a sandwich-like coordination of the cation with two crown-ether molecules. All title compounds show visible emission, whereof 1, 2, and 5 have good luminescence efficiencies with quantum yields of 47, 39, and 21%, respectively. These luminescence properties are compared with recently realized compounds such as Mn3Cl6(18-crown-6)2, MnI2(18-crown-6), Mn3I6(18-crown-6)2, or Mn2I4(18-crown-6), which have significantly higher quantum yields of 98 and 100%. Based on a comparison of altogether nine crown-ether coordination compounds, the structural features can be correlated with the luminescence efficiency, which allows extraction of those conditions encouraging intense emission and high quantum yields.

GaSeCl5O: A Molecular Compound with Very Strong SHG Effect.

GaSeCl5O is a new inorganic molecular compound prepared from SeO2, SeCl4, and GaCl3 at 50 °C in quantitative yield. The structure of the title compound is described by GaCl3(OSeCl2) molecules with a tetrahedrally coordinated Ga atom and a pseudo-tetrahedrally coordinated Se atom (including lone pair of Se(IV)) that are bridged by oxygen. GaSeCl5O crystallizes in the polar chiral space group P61, which is rarely observed for molecular structures. The compound is characterized by X-ray structure analysis based on single crystals and powder samples, thermogravimetry, infrared and Raman spectroscopy as well as by second harmonic generation (SHG) measurements. The experimental data are complemented by density functional theory calculations. GaSeCl5O shows one of the strongest SHG signals known in the visible part of the electromagnetic spectrum (480-700 nm) with an SHG intensity 10 times higher than potassium dihydrogen phosphate (KDP). This is in accordance with the phase matchability and a strong dipole moment (|µ| = 8.3 D for a molecule in the crystal lattice). Such a strong SHG effect is also remarkable since GaSeCl5O-unlike most of the materials with strong SHG intensity-is an inorganic molecular compound.

Liquid-Phase Synthesis of Highly Reactive Rare-Earth Metal Nanoparticles.

The first liquid-phase synthesis of high-quality, small-sized rare-earth metal nanoparticles (1-3 nm)-ranging from lanthanum as one of the largest (187 pm) to scandium as the smallest (161 pm) rare-earth metal-is shown. Size, oxidation state, and reactivity of the nanoparticles are examined (e.g., electron microscopy, electron spectroscopy, X-ray absorption spectroscopy, selected reactions). Whereas the nanoparticles are highly reactive (e.g. in contact to air and water), they are chemically stable as THF suspensions and powders under inert conditions. The reactivity can be controlled to obtain inorganic and metal-organic compounds at room temperature.

[BMIm]2[Mn(CO)3(GeI3)3]: Carbonyl Compound with an {MnGe3} Cluster Unit.

Orange, transparent crystals of [BMIm]2[Mn(CO)3(GeI3)3] (BMIm: 1-butyl-3-methylimidazolium) are obtained by reacting GeI4, [Mn(CO)6][AlCl4], and Ph3GeH in the ionic liquid [BMIm][NTf2]. [Mn(CO)6][AlCl4] and triphenylgermane turn out to be essential as reactive carbonyl precursors and for the reduction of GeI4. According to X-ray structure analysis based on single crystals, the title compound exhibits a novel {MnGe3} cluster unit with Mn-Ge single bonds and surprisingly short distances (236-241 pm). Although sensitive to oxygen/moisture, the carbonyl compound is stable up to a temperature of 150 °C. Mass spectrometry (MS) shows [Mn(CO)3(GeI3)2]-, [Mn(CO)3(GeI3)I]-, and [GeI3]- as decomposition fragments in the gas phase. In addition to crystal structure analysis and MS, the title compound is characterized by energy-dispersive X-ray spectroscopy (EDXS), thermogravimetry (TG), optical spectroscopy (UV-visible), infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations.

Structural Properties and ELNES of Polycrystalline and Nanoporous Mg3N2.

Nanoporous, high-purity magnesium nitride (Mg3N2) was synthesized with a liquid ammonia-based process, for potential applications in optoelectronics, gas separation and catalysis, since these applications require high material purity and crystallinity, which has seldom been demonstrated in the past. One way to evaluate the degree of crystalline near-range order and atomic environment is electron energy-loss spectroscopy (EELS) in a transmission electron microscope. However, there are hardly any data on Mg3N2, which makes identification of electron energy-loss near-edge structure (ELNES) features difficult. Therefore, we have studied nanoporous Mg3N2 with EELS in detail in comparison to EELS spectra of bulk Mg3N2, which was analyzed as a reference material. The N-K and Mg-K edges of both materials are similar. Despite having the same crystal structure, however, there are differences in fine-structural features, such as shifts and absences of peaks in the N-K and Mg-K edges of nanoporous Mg3N2. These differences in ELNES are attributed to coordination changes in nanoporous Mg3N2 caused by the significantly smaller crystallite size of 2-6 nm compared to the larger (25-125 nm) crystal size in a bulk material.

[SnI8 {Fe(CO)4 }4 ]2+ : Highly Coordinated Sn+II I8 Subunit with Fragile Carbonyl Clips.

[SnI8 {Fe(CO)4 }4 ][Al2 Cl7 ]2 contains the [SnI8 {Fe(CO)4 }4 ]2+ cation with an unprecedented highly coordinated, bicapped SnI8 prism. Given the eightfold coordination with the most voluminous stable halide, it is all the more surprising that this SnI8 arrangement is surrounded only by fragile Fe(CO)4 groups in a clip-like fashion. Inspite of a predominantly ionic bonding situation in [SnI8 {Fe(CO)4 }4 ]2+ , the I- ⋅⋅⋅I- distances are considerably shortened (down to 371 pm) and significantly less than the van der Waals distance (420 pm). The title compound is characterized by single-crystal structure analysis, spectroscopic methods (EDXS, FTIR, Raman, UV/Vis, Mössbauer), thermogravimetry, and density functional theory methods.

Lithiumpyridinyl-Driven Synthesis of High-Purity Zero-Valent Iron Nanoparticles and Their Use in Follow-Up Reactions.

The synthesis of zero-valent iron (Fe(0)) nanoparticles in pyridine using lithium bipyridinyl ([LiBipy]) or lithium pyridinyl ([LiPy]) is presented. FeCl3 is used as the most simple starting material and reduced either in a [LiBipy]-driven two-step approach or in a [LiPy]-driven one-pot synthesis. High-quality nanoparticles are obtained with uniform, spherical shape, and mean diameters of 2.9 ± 0.5 nm ([LiBipy]) or 4.1 ± 0.7 nm ([LiPy]). The as-prepared, high purity Fe(0) nanoparticles are monocrystalline. In addition to particle characterization (high-resolution transmission electron microscopy, scanning transmission electron microscopy, dynamic light scattering), composition and purity are examined in detail based on electron diffraction, X-ray powder diffraction, elemental analysis, infrared spectroscopy, 57 Fe Mössbauer spectroscopy, and magnetic measurements. Due to their small size and high purity, the Fe(0) nanoparticles are highly reactive. They can be used in follow-up reactions to obtain a variety of iron compounds, which is exemplarily shown for the transformation to iron carbide (Fe3 C) nanoparticles, the reaction with sulfur to obtain FeS nanoparticles, or the direct reaction with pentamethylcyclopentadiene to FeCp*2 (Cp*: pentamethylcyclopentadienyl).

Reactivity of ZrO(MFP) and ZrO(RP) Nanoparticles with LnCl3 for Solvatochromic Luminescence Modification and pH-Dependent Optical Sensing.

The luminescence of the inorganic-organic hybrid nanoparticles ZrO(MFP) (MFP=methylfluorescein phosphate) and ZrO(RP) (RP=resorufin phosphate) was modified by addition of different rare earth halides LnCl3 . The resulting composite materials form dispersible nanoparticles that exhibit modified nanoparticle fluorescence depending on the rare earth ion. The resulting chromaticity of the luminescence is further variable by the employment of different solvents for ZrO(MFP)-based composite systems. The strong solvatochromic effect of the MFP chromophore leads to different luminescence chromaticities of the composite materials between green, yellow, and blue in THF, toluene, and dichloromethane, respectively. The luminescence of ZrO(RP)-based composite particles can be modified between the red and blue spectral regions in dependence on the applied reaction temperature. Beside a luminescence shift that is derived from nanoparticle modification by LnCl3 , a strong turn-on effect of ZrO(RP) particles results after contact with different Brønsted acids and bases in combination with a respective chromaticity shift. Both effects enable the potential employment of such particles as highly sensitive optical pH sensors.

Samarium Polyarsenides Derived from Nanoscale Arsenic.

Zintl phases of arsenic and molecular compounds containing Zintl-type polyarsenide ions are of fundamental interest in basic and applied sciences. Unfortunately, the most obvious and reactive arsenic source for the preparation of defined molecular polyarsenide compounds, yellow arsenic As4 , is very inconvenient to prepare and neither storable in pure form nor easy to handle. Herein, we present the synthesis and reactivity of elemental As0 nanoparticles (As0 Nano , d=7.2±1.8 nm), which were successfully utilized as a reactive arsenic source in reductive f-element chemistry. Starting from [Cp*2 Sm] (Cp*=η5 -C5 Me5 ), the samarium polyarsenide complexes [(Cp*2 Sm)2 (µ-η2 :η2 -As2 )] and [(Cp*2 Sm)4 As8 ] were obtained from As0 nano , thereby generating the largest molecular polyarsenide of the f-elements and circumventing the use of As4 in preparative chemistry.

Fluorescent Sulfonate-Based Inorganic-Organic Hybrid Nanoparticles for Staining and Imaging.

Sulfonate-based inorganic-organic hybrid nanoparticles (IOH-NPs) with the general saline composition [Gd(OH)]2+n/2[ Rdye(SO3) n] n- showing optical absorption and emission in the blue to red spectral regime are presented for the first time. All IOH-NPs are prepared via straightforward aqueous synthesis and instantaneously result in colloidally highly stable suspensions with mean particle diameters of 40-50 nm and high zeta potentials (-20 to -40 mV at pH 7.0). Specifically, the IOH-NPs comprise [Gd(OH)]2+2[CSB]4-, [Gd(OH)]2+2[DB71]4-, [Gd(OH)]2+[NFR]2-, [Gd(OH)]2+[AR97]2-, and [Gd(OH)]2+2[EB]4- showing blue, orange, red, and infrared absorption and emission ([CSB]: Chicago Sky Blue; [DB71]: Direct Blue 71; [NFR]: Nuclear Fast Red; [AR97]: Acid Red 97; [EB]: Evans Blue). The novel IOH-NPs are characterized by electron microscopy, dynamic light scattering, infrared spectroscopy, energy-dispersive X-ray analysis, thermogravimetry, elemental analysis, and fluorescence spectroscopy. In vitro studies based on HeLa and HUVEC cells were exemplarily performed with [Gd(OH)]2+2[EB]4- IOH-NPs and show intense fluorescence and only moderate toxicity at concentrations of 1 to 10 µg/mL. Based on aqueous synthesis, good colloidal stability, absence of severely toxic metals (e.g., Cd2+, Pb2+), use of molecular dyes that are already known for staining in cell biology and histology, extremely high dye load per nanoparticle (70-80 wt %), and blue to red absorption and fluorescence, the sulfonate-based IOH-NPs can be highly interesting for staining, fluorescence microscopy, and optical imaging.

Samarium Polystibides Derived from Highly Activated Nanoscale Antimony.

Zintl ions in molecular compounds are of fundamental interest for basic research and application. Two reactive antimony sources are presented that allow direct access to molecular polystibide compounds. These are Sb amalgam (Sb/Hg) and ultrasmall Sb0 nanoparticles (d=6.6±0.8 nm), which were used independently as precursors for the synthesis of the largest f-element polystibide, [(Cp*2 Sm)4 Sb8 ]. Whereas the reaction of the nanoparticles with [Cp*2 Sm] directly led to [(Cp*2 Sm)4 Sb8 ], Sm/Sb/Hg intermediates were isolated when using Sb/Hg as the precursor. These Sm/Sb/Hg intermediates [{(Cp*2 Sm)2 Sb}2 (µ-Hg)] and [{(Cp*2 Sm)3 (µ4 ,η1:2:2:2 -Sb4 )}2 Hg] were synthetically trapped and structurally characterized, giving insight in the formation mechanism of polystibide compounds.