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In this report, we describe the X-ray luminescent properties of two lanthanide-based nanoscale metal-frameworks (nMOFs) and their potential as novel platforms for optical molecular imaging techniques such as X-ray excited radioluminescence (RL) imaging. Upon X-ray irradiation, the nMOFs display sharp tunable emission peaks that span the visible to near-infrared spectral region (∼400-700 nm) based on the identity of the metal (Eu, Tb, or Eu/Tb). Surface modification of the nMOFs with polyethylene glycol (PEG) resulted in nanoparticles with enhanced aqueous stability that demonstrated both cyto- and hemo-compatibility important prerequisites for biological applications. Importantly, this is the first report to document and investigate the radioluminescent properties of lanthanide nMOFs. Taken together, the observed radioluminescent properties and low in vitro toxicity demonstrated by the nMOFs render them promising candidates for in vivo translation.

Due to their complementary activity, the use of DNA damage repair (DDR) inhibitors during radiotherapy (RT) has yielded promising results. Unfortunately, this approach is often hindered by toxicity and poor in vivo stability of the DDR inhibitors. Nanoscale metal-organic frameworks (nMOFs) represent an emerging class of crystalline materials which exhibit advantageous properties over traditional nanomaterials and demonstrate great potential in oncology. Herein, a unique, synergistic treatment strategy for enhancing the therapeutic efficacy of RT via nMOF-mediated drug delivery and RT enhancement was evaluated. A nMOF containing the high-Z element Hf and the ligand 1,4-dicarboxybenzene (Hf-BDC) was synthesized and loaded with the two DDR inhibitor drugs, talazoparib and buparlisib (TB@Hf-BDC-PEG). TB@Hf-BDC-PEG augmented RT by increasing reactive oxygen species generation and thus DNA damage of which repair was inhibited thereafter. Synergistic enhancement was demonstrated in vivo where the combination of concurrent radiation with intravenous TB@Hf-BDC-PEG administration resulted in improved tumor control and increased apoptosis. Importantly, no apparent toxicity was observed with nMOF treatment, supporting its potential as an attractive candidate over traditional nanomaterials. This work provides the first report of nMOFs employed to enhance the therapeutic response to RT through DDR inhibitor delivery and physical radiation dose enhancement.

Herein, we report an aerobic synthesis method to produce bismuth nanoparticles (Bi NPs) with average diameters in the range 40-80 nm using commercially available bismuth triiodide (BiI3) as the starting material; the method uses only readily available chemicals and conventional laboratory equipment. Furthermore, size data from replicates of the synthesis under standard reaction conditions indicate that this method is highly reproducible in achieving Bi NP populations with low standard deviations in the mean diameters. We also investigated the mechanism of the reaction, which we determined results from the reduction of a soluble alkylammonium iodobismuthate precursor species formed in situ. Under appropriate concentration conditions of iodobismuthate anion, we demonstrate that burst nucleation of Bi NPs results from reduction of Bi3+ by the coordinated, redox non-innocent iodide ligands when a threshold temperature is exceeded. Finally, we demonstrate phase transfer and silica coating of the Bi NPs, which results in stable aqueous colloids with retention of size, morphology, and colloidal stability. The resultant, high atomic number, hydrophilic Bi NPs prepared using this synthesis method have potential for application in emerging x-ray contrast and x-ray therapeutic applications.

Recent studies have shown the presence of an amorphous surface layer in nominally crystalline silicon nanocrystals (SiNCs) produced by some of the most common synthetic techniques. The amorphous surface layer can serve as a source of deep charge traps, which can dramatically affect the electronic and photophysical properties of SiNCs. We present results of a scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS) study of individual intragap states observed on the surfaces of hydrogen-passivated SiNCs deposited on the Au(111) surface. STS measurements show that intragap states can be formed reversibly when appropriate voltage–current pulses are applied to individual SiNCs. Analysis of STS spectra suggests that the observed intragap states are formed via self-trapping of charge carriers injected into SiNCs from the STM tip. Our results provide a direct visualization of the charge trap formation in individual SiNCs, a level of detail which until now had been achieved only in theoretical studies.

High-density inorganic nanoparticles have shown promise in medical applications that utilize radiation including X-ray imaging and as radiation dose enhancers for radiotherapy. We have developed an aqueous synthetic method to produce small (~ 2 nm) iridium nanoparticles (IrNPs) by reduction of iridium(III) chloride using a borohydride reducing agent. Unlike other solution-based synthesis methods, uniform and monodispersed IrNPs are produced without the use of surfactants or other solubilizing ligands. These nanoparticles are highly crystalline as observed by X-ray diffraction and high-resolution transmission electron microscopy (TEM). In vitro metabolic toxicity assays using hepatocyte and macrophage cells demonstrate that both IrNPs and iridium(III) chloride are well tolerated at concentrations of up to 10 μM iridium. Furthermore, the IrNPs were assessed in a hemolytic assay and found to have no significant impact on red blood cells when exposed to concentrations up to 100 μM. Overall, these results support the potential for the in vivo application of this nanomaterial. Electronic supplementary material The online version of this article (10.1186/s11671-018-2621-3) contains supplementary material, which is available to authorized users.

Visibly emissive silicon nanoparticles (Si NPs) were obtained via annealing of (HSiO1.5)n polymer, followed by chemical etching. The hydride-terminated Si NPs (H-Si NPs) were surface-functionalized via thermal hydrosilylation with 1-decene and were dispersed in straight chain alcohols varying in carbon chain length (C1–C10). The initial red photoluminescence (PL) (λmax,em ∼580 nm) observed from hexane dispersions of the decane-terminated Si NPs (dec-Si NPs) became weaker upon exposure to alcohols smaller than a minimum chain length, commensurate with appearance of strong, blue PL (λmax,em ∼450 nm). A suite of spectroscopic and microscopic techniques was employed to study and correlate the change in Si NP PL with composition and/or size changes to the Si NPs. The results of these studies support that the conversion from red to blue PL originates from dangling bond defect passivation by small alcohol molecules, resulting in an enhanced blue/red PL ratio. The dangling bond defect (Si•) is supported by reacti...

To facilitate the potential application of TiO2 as an efficient photocatalyst, the modulation of its band gap and electrical structure is of great significance. Herein, we report a very simple nitrogen (N)-doping method to obtain N-doped TiO2, which is hybridized with graphene sheets at a temperature as low as 180 °C and using an ammonia solution as the N source and reaction medium. X-ray photoelectron spectroscopy analysis revealed that the atomic N level could reach 2.4 atomic percent when the reaction time was 14 h. Photoluminescence (PL) emission spectra indicated that N-doped TiO2/graphene composites have drastically suppressed TiO2 PL intensity when compared to undoped TiO2, confirming the lower recombination rate of electron–hole pairs in the N-doped TiO2. Additionally, photodegradation data showed that the decomposition rate of methylene blue with our N-doped TiO2/graphene photocatalyst is twice as fast as a commercial Degussa P25 catalyst. Furthermore, density functional theory (DFT) calculations...

To greatly improve the electrocatalytic activity for methanol oxidation, high-quality exfoliated graphene decorated with uniform Pt nanocrystals (NCs) (3 nm) have been prepared by a very simple, low-cost and environmentally benign process. During the entire process, no surfactant and no halide ions were involved, which not only enabled very clean surface of Pt/graphene leading to excellent conductivity, but also greatly improved the electrocatalyst tolerance to carbon monoxide poisoning (Pt/graphene, If/Ib = 1.197), compared to commercial Pt/C (If/Ib = 0.893) catalysts. To maximize the electrocatalytic performance and minimize the amount of precious Pt, Pt–M/graphene (M = Pd, Co) hybrids have also been prepared, and these hybrids have much larger electrochemically active surface areas (ECSA), which are 4 (PtPd/graphene) and 3.3 (PtCo/graphene) times those of commercial Pt/C. The PtPd/graphene and PtCo/graphene hybrids also have remarkably increased activity toward methanol oxidation (If/Ib = 1.218 and 1.558). Furthermore, density functional theory (DFT) simulations demonstrate that an electronic interaction occurred between Pt atoms and graphene, indicating that graphene substrate plays a crucial role in regulating the electron structure of attached Pt atom, which confirmed that the increased efficiency of methanol oxidation was due to the synergetic effects of the hybrid structure.

Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color.

The photophysical properties of silicon semiconductor nanocrystals (SiNCs) are extremely sensitive to the presence of surface chemical defects, many of which are easily produced by oxidation under ambient conditions. The diversity of chemical structures of such defects and the lack of tools capable of probing individual defects continue to impede understanding of the roles of these defects in SiNC photophysics. We use scanning tunneling spectroscopy to study the impact of surface defects on the electronic structures of hydrogen-passivated SiNCs supported on the Au(111) surface. Spatial maps of the local electronic density of states (LDOS) produced by our measurements allowed us to identify locally enhanced defect-induced states as well as quantum-confined states delocalized throughout the SiNC volume. We use theoretical calculations to show that the LDOS spectra associated with the observed defects are attributable to Si-O-Si bridged oxygen or Si-OH surface defects.

Taking advantage of a pH-dependent solubility equilibrium, we have developed an aqueous synthesis of chemically and colloidally stable bismuth(0) glyconanoparticles. The synthetic method results in potentially biocompatible elemental bismuth nanoparticles (BiNPs) and involves the reduction of aqueous bismuth(III) cations by sodium borohydride in a pH-controlled solution. Medical-grade dextran (75 000 MW) was found to protect the nanocrystals from oxidation, in addition to promoting colloidal stability and separation of individual nanocrystallites. The rate of particle formation was dependent on synthesis pH, and decreasing the reaction rate by increasing the pH produced a greater number of individual and isolated Bi(0) nanocrystals. Stable, aqueous colloids of the dextran-coated BiNPs decomposed under prolonged light exposure, and the NPs dissolved both in acidic solutions (pH 12), but were stable in phosphate buffered saline solution (pH 7.4) and in other aqueous so...

In order to improve specific capacitance and limit electrical resistance, high-quality exfoliated graphene decorated with transition metal (Fe, Mn, Co) oxide nanoparticles (NPs) has been successfully synthesized without the use of surfactantvia a simple, general, environmentally-friendly chemical process. The specific capacitance of as-prepared graphene/Mn3O4 composite reach 239.6 F/g, when employed as the anode material in neutral NaCl electrolyte solutions (cf. 98.2 F/g for pristine graphene and 141.4 F/g for pure Mn3O4 NPs), which indicate the synergetic effects from both graphene and attached Mn3O4 NPs. Moreover, the high conductivity of graphene eliminates the need for conductive carbon black as fillers. The current density of graphene/Mn3O4 reached as high as 4.5 A g−1 which is much higher than that of graphene oxide (GO) or reduced GO-based composites. This significant enhancement of capacitance and current density was attributed to the surfactant-free approach to hybridize graphene with transition metal oxide NPs, the excellent conductivity of pristine graphene combined with its large surface area, as well as a uniform distribution of NPs on the clean surface of conductive graphene. Thus the low-toxicity, inexpensive graphene-based hybrids show promising utility as high current density electrode materials for supercapacitor applications.

We have developed a versatile, one-step melt synthesis of water-soluble, highly emissive silicon nanoparticles using bi-functional, low-melting solids (such as glutaric acid) as reaction media. Characterization through transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy shows that the one-step melt synthesis produces nanoscale Si cores surrounded by a silicon oxide shell. Analysis of the nanoparticle surface using FT-IR, zeta potential, and gel electrophoresis indicates that the bi-functional ligand used in the one-step synthesis is grafted onto the nanoparticle, which allows for tuning of the particle surface charge, solubility, and functionality. Photoluminescence spectra of the as-prepared glutaric acid-synthesized silicon nanoparticles show an intense blue-green emission with a short (ns) lifetime suitable for biological imaging. These nanoparticles are found to be stable in biological media and have been used to examine cellular uptake and distribution in live N2a cells.

Six new inorganic-organic salts, all containing iodobismuthate anions and d-metal coordination cations, were synthesized solvothermally from reactions of bismuth iodide, a transition metal (M) nitrate salt (M = Co, Fe or Zn), and a heterocyclic, chelating organic ligand: 1,10-phenanthroline (1,10-phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (TMphen), or 2,2':6',2''-terpyridine (tpy). All six compounds were structurally analyzed by single crystal X-ray diffraction, including variable temperature crystallographic analysis to monitor for structural changes. Furthermore, those containing novel anions and achieved in high yield were additionally characterized by solid-state UV visible spectroscopy at room temperature. [Co(1,10-phen)(3)][Bi(3)I(11)] (1), [Fe(1,10-phen)(3)][Bi(3)I(11)] (2), and [Zn(1,10-phen)(3)][Bi(3)I(11)] (3) are isostructural. They crystallize in the monoclinic space group P2(1)/n and contain the unprecedented iodobismuthate anion, [Bi(3)I(11)](2-), which exhibits near D(3h) symmetry and has an unusual arrangement of three cis face-sharing BiI(6) octahedra. [Co(TMPhen)(3)](2)[Bi(2)I(9)][I] (4), which crystallizes in the trigonal space group P-31c, and [Co(tpy)(2)](2)[Bi(2)I(9)][I] (5) and [Zn(tpy)(2)](2)[Bi(2)I(9)][I] (6), which are isostructural and crystallize in the monoclinic space group C2/c, contain the discrete binuclear [Bi(2)I(9)](3-) anion, common in previously reported iodobismuthate compounds. In addition they contain unusual isolated I(-) anions, which are rarely encountered in iodobismuthate phases. Compounds 1-6 show constitutional similarities while utilizing different organic ligands and illustrate the sensitive dependence of reaction conditions on the identity of the halometalate anion formed. Additionally, all six compounds and the starting material BiI(3) are thermochromic; the origin of this behavior is spectroscopically and crystallographically investigated.

Single crystals of EuGa2Pn2 (Pn = P, As) were grown from a molten Ga flux and characterized by single-crystal X-ray diffraction at 100(1) K. They are isostructural and crystallize in a new structure type (monoclinic, P2/m, a = 9.2822(9) A, b = 3.8967(4) A, c = 12.0777(11) A, β = 95.5220(10)°, R1 = 0.0148, wR2 = 0.0325 (EuGa2P2) and a = 9.4953(7) A, b = 4.0294(3) A, c = 12.4237(9) A, β = 95.3040(10)°, R1 = 0.0155, wR2 = 0.0315 (EuGa2As2)). The structures consist of alternating layers of two-dimensional Ga2Pn2 anions and Eu cations. The anion layers are composed of Ga2Pn6 staggered, ethane-like moieties having a rare Ga−Ga bonding motif; these moieties are connected in a complex fashion by means of shared Pn atoms. Both structures show small residual electron densities that can be modeled by adding a Eu atom and removing two bonded Ga atoms, resulting in structures (

Large, high quality single crystals of a new Zintl phase, EuIn(2)As(2), have been synthesized from a reactive indium flux. EuIn(2)As(2) is isostructural to the recently reported phase EuIn(2)P(2), and it is only the second reported member of the group of compounds with formula AM(2)X(2) (A = alkali, alkaline earth, or rare earth cation; M = transition or post-transition metal; and X = Group 14 or 15 element) that crystallizes in the hexagonal space group P6(3)/mmc (a = 4.2067(3) A, c = 17.889(2) A and Z = 2). The structure type contains layers of A(2+) cations separated by [M(2)X(2)](2-) layers along the crystallographic c-axis. Crystals of the title compound were mounted for magnetic measurements, with the crystallographic c-axis oriented either parallel or perpendicular to the direction of the applied field. The collective magnetization versus temperature and field data indicate two magnetic exchange interactions near 16 K, one involving Eu(2+)...Eu(2+) intralayer coupling and the other involving Eu(2+)...Eu(2+) coupling between layers. EuIn(2)As(2) is metallic and magnetoresistive, as is the isostructural phosphide, and both compounds have coincident resistivity and magnetic ordering transitions, consistent with the observation of colossal magnetoresistance. Negative colossal magnetoresistance (MR = {[rho(H) - rho(0)]/rho(H)} x 100%) of up to -143% (at T = 17.5 K, H = 5 T) is observed for EuIn(2)As(2), approximately half of that observed for the more resistive phosphide, which has a higher magnetic ordering temperature and local moment coupling strength.

[BiI2(tpy)2][Bi2I7(tpy)] (1) (tpy = 2,2′:6′2′′-terpyridine), a new compound containing a discrete bismuth halide anion, has been synthesized solvothermally and characterized by single crystal X-ray diffraction. The solvothermal reaction between BiI3, Zn(NO3)2 · 6H2O, and 2,2′:6′2′′-terpyridine in an ethanol/water solvent mixture resulted in the title compound. The anion and cation of this compound both contain bismuth, iodide ligands, and the organic ligand. The anion is composed of two face-sharing bismuth polyhedra, one of which is coordinated in a tridentate fashion to a disordered tpy ligand; and the remaining coordination sites at each Bi center are occupied by iodide ligands. The cation of the compound is a distorted, eight-coordinate polyhedron with a bismuth center, two iodide ligands, and six nitrogen atoms from two, tridentate tpy ligands. [BiI2(tpy)2][Bi2I7(tpy)] crystallizes in the triclinic space group P $$ \overline{1} $$ with the following lattice parameters: a = 10.0744(5) A, b = 16.6115(8) A, c = 18.5333(9) A, α = 102.6490(10)°, β = 101.0850(10)°, and γ = 93.9160(10)°. The title compound, [BiI2(tpy)2][Bi2I7(tpy)], was synthesized solvothermally by the reaction between BiI3 and 2,2′:6′2′′-terpyridine. Single crystal X-ray diffraction analysis reveals that the molecular structure contains one anion and one cation, both of which contain bismuth, iodine, and the tpy ligand, a situation not typically observed in these types of compounds.

Three pairs of novel, isostructural polymeric iodometallate compounds, [H1,10-phen](H2O)1.41[AgI2] (1) ([H1,10-phen]+ = [1,10-phenanthrolinium]+), [H1,10-phen](H2O)1.42[CuI2] (2), [Co(tpy)2][Bi2I8] (3) (tpy = 2,2′:6′2″-terpyridine), [Fe(tpy)2][Bi2I8] (4), [Co(1,10-phen)3][Pb3I8]·H2O (5) (1,10-phen = 1,10-phenanthroline), and [Fe(1,10-phen)3][Pb3I8]·0.5(H2O) (6) have been synthesized solvothermally and characterized by single crystal X-ray diffraction. Compounds 1 and 2 are isostructural and crystallize in the orthorhombic space group Cmma with lattice parameters of a = 6.7063(7) A, b = 17.6051(18) A, c = 12.7088(13) A and a = 6.5770(3) A, b = 17.5245(8) A, c = 12.5515(6) A, respectively. The polymeric anionic chains in 1 and 2 are formed by edge-sharing MI4 (M = Ag, Cu) tetrahedra. Compounds 3 and 4 are isostructural and crystallize in the monoclinic space group P21/n with lattice parameters of a = 16.5085(7) A, b = 16.0392(7) A, c = 16.5115(7) A, β = 97.4710(10)° and a = 16.4478(6) A, b = 16.0645(6) A, c = 16.4498(6) A, β = 97.4490(10)°, respectively. Both structures contain the first observed, face-sharing [Bi2I8]2− anion cluster that is linked via corner sharing into infinite zig-zag anionic chains. Compounds 5 and 6 are isostructural and crystallize in the triclinic space group P 1 ¯ with lattice parameters of a = 11.8798(5) A, b = 15.2805(7) A, c = 16.1889(7) A, α = 63.9240(10)°, β = 74.0420(10)°, γ = 73.2540(10)° and a = 11.7889(5) A, b = 15.3224(6) A, c = 16.2584(6) A, α = 64.1920(10)°, β = 73.5600(10)°, and γ = 73.7120(10)°, respectively. Compounds 5 and 6 contain infinite [Pb3I8]2− chains in which the three crystallographically unique Pb2+ ions are found in sets of three trans face-sharing octahedra. These face-sharing trimers are observed in pairs that share three edges, and the pairs are further connected into 1-D chains by edge sharing with neighboring 2 × 3 units.

A new iron(II) scorpionate complex, {Fe[HC(3,4,5-Me3pz)3]2}(I)2 (pz = pyrazolyl) (1), and two novel compounds containing low-dimensional poly(iodobismuthate) anions [1,2-Et2-3,4,5-Me3pz]4[Bi4I16] ([1,2-Et2-3,4,5-Me3pz]+ = [1,2-diethyl-3,4,5-trimethyl-pyrazolium]+) (2), and [H(1,10-phen)][BiI4]·(H2O) ([H(1,10-phen)]+ = [1,10-phenanthrolinium]+) (3), have been synthesized and characterized by single crystal X-ray diffraction. Crystals of 2 resulted from the solvothermal reaction of BiI3 and {Fe[HC(3,4,5-Me3pz)3]2}(I)2 in an ethanol/water solvent mixture. The anion of this compound is discrete (0-D) and consists of four slightly distorted BiI6 octahedra joined in an edge-sharing arrangement, and the cation is a decomposition/solvent attack product of the iron scorpionate complex. Crystals of 3 resulted from the solvothermal reaction of BiI3, 1,10-phenanthroline, and CuI in an ethanol/water solvent mixture. [H(1,10-phen)][BiI4]·(H2O) contains 1-D chains of BiI6 octahedra and a protonated phenanthroline/water molecule complex. Both 2 and 3 are thermochromic compounds as their colors change, respectively, from orange at 296 K to yellow upon cooling to 100 K and from red-orange at 296 K to orange at 100 K. Crystallographic data at both temperatures were recorded for each sample and are reported here. The crystallographic data indicate that interatomic distances (Bi–I and Bi⋯Bi) within the inorganic anions change as a function of temperature, and it is believed that these changes are associated with the observation of thermochromism. {Fe[HC(3,4,5-Me3pz)3]2}(I)2 (1) crystallizes in the monoclinic space group P21/n with the following lattice parameters at 150(1) K: a = 10.8489(5) A, b = 17.6642(9) A, c = 15.4131(8) A, β = 102.4860(10)°. [Et2Me3pz]4[Bi4I16] (2) and [H(1,10-phen)][BiI4]·(H2O) (3) both crystallize in the triclinic space group P 1 ¯ with the following lattice parameters for 2 at 296(1) K and 100(1) K, respectively: a = 11.2923(4) A, b = 13.6412(5) A, c = 15.0824(6) A, α = 78.2090(10)°, β = 71.9670(10)°, and γ = 67.4020(10)°; a = 11.0963(7) A, b = 13.4158(8) A, c = 14.9840(9) A, α = 79.1450(10)°, β = 71.1310(10)°, and γ = 68.1360(10)°. Lattice parameters for 3 at 296(1) K and 100(1) K, respectively, are as follows: a = 7.7590(4) A, b = 11.1477(5) A, c = 12.0731(6) A, α = 77.6570(10)°, β = 79.1900(10)°, and γ = 71.2950(10)°; a = 7.7000(4) A, b = 10.9265(6) A, c = 11.9748(7) A, α = 78.1020(10)°, β = 79.9940(10)°, and γ = 71.8380(10)°.

The inorganic-organic salts (H{sub 2}TMDP){sub 3}(Bi{sub 2}I{sub 9}){sub 2} (1), (H{sub 2}TMDP){sub 2}(Bi{sub 4}I{sub 16}).2EtOH (2), (H{sub 2}TMDP){sub 2}(Bi{sub 6}I{sub 22}).2EtOH (3), and (H{sub 2}TMDP){sub 2}(Bi{sub 6}I{sub 22}) (4) were synthesized and structurally characterized from the solvothermal reaction of 1,3-bis-(4-piperidyl)propane (TMDP) and BiI{sub 3} by adjusting the relative ratio of the reactants. The anions of the compounds consist of 2 (1), 4 (2), or 6 (3 and 4) BiI{sub 6} polyhedra, which are joined by face- (1) or edge-sharing (2-4) to form discrete anions. The size of the discrete anion, in terms of the number of connected polyhedra, is observed to increase as the ratio of BiI{sub 3} to TMDP is increased. A related compound (H{sub 2}TMDP)(Bi{sub 3}I{sub 11}).(H{sub 2}O) (5) was synthesized and structurally characterized using the same two reactants in the presence of HF. The anion of 5 is polymeric rather than discrete, with a trioctahedral repeat unit.

A series of new coordination compounds has been synthesized using the organic ligand 1,2-dimethoxy-4,5-bis(2-pyridylethynyl)benzene (dmpeb). The compounds all form dimers consisting of two metal cations bridged by two ligand molecules. Charge balance is provided by halide ligands, and the four-coordinate metal centers are distorted from the ideal tetrahedral environment. [CoCl2(dmpeb)]2 (1) crystallizes in the monoclinic space group P21/n with a = 8.5272(6) A, b = 18.3653(13) A, c = 13.3493(9) A, β = 103.574(2)∘, V = 2032.2(2) A3, Z = 2. [ZnCl2(dmpeb)]2 (2) is isostructural to 1 and has the cell parameters a = 8.5495(4) A, b = 18.4049(8) A, c = 13.3692(6) A, β = 103.4460(10)∘, V = 2046.01(16) A3, Z = 2. [ZnBr2(dmpeb)]2 (3) is also isostructural to 1 with a = 8.7882(5) A, b = 18.7260(12) A, c = 13.3857(8) A, β = 102.5990(10)∘, V = 2149.8(2) A3, Z = 2. Additionally, the compounds [ZnI2(dmpeb)]2 (4, cell parameters: a = 8.9650(5) A, b = 19.1251(10) A, c = 13.4160(7) A, β = 101.1660(10)∘, V = 2256.7(2) A3, Z = 2), [HgCl2(dmpeb)]2 (5, cell parameters: a = 8.8457(7) A, b = 18.4030(15) A, c = 13.3711(11) A, β = 104.246(2)∘, V = 2109.7(3) A3, Z = 2), and [HgBr2(dmpeb)]2 (6, cell parameters: a = 9.0576(5) A, b = 18.8634(11) A, c = 13.4535(8) A, β = 102.9780(10)∘, V = 2239.9(2) A3, Z = 2) are also isostructural to 1. A seventh dimeric compound, [HgI2(dmpeb)]2, not isostructural to the others was also characterized by X-ray crystallography. [HgI2(dmpeb)]2 (7) crystallizes in the triclinic space group P-1 with a = 8.8028(5) A, b = 12.0990(7) A, c = 12.4082(7) A, α = 109.7240(10)∘, β = 107.3680(10)∘, γ = 93.0880(10)∘, V = 1169.57(12) A3, Z = 1.

Four new, non-interpenetrated square-grid coordination polymers, namely [Mn(L)2(NO3)2]infinity (1), [[Cd(L)2(NO3)2].solvate]infinity (2), [Cd(L)2(NO3)2]infinity (3), and [[Zn(L)2](BF4)2.(C6H6)2.564.(DMF)1.576.(MeOH, H2O)3.454]infinity (4), were synthesized using the new, extremely long N,N'-type ligand: 2,5-bis(4'-(imidazol-1-yl)benzyl)-3,4-diaza-2,4-hexadiene (L). The reaction of Cd(NO3)2 with L leads to two novel structures sharing the same framework composition, [Cd(L)2(NO3)2]infinity, which have different arrangements of L around the metal centers. Both the channel-containing structure and the nonporous structure can be formed by choice of the appropriate solvent system. Moreover, the less stable, channel-containing form readily converts into the more stable, condensed structure upon removal of the guest molecules from the channels.

A new flexible ligand, 1,5-bis(8-oxaquinoline)-3-methylpentane (C5MeOQ), was synthesized and used in the preparation of the new dinuclear copper(II) complex 1: [Cu2(μ-OMe)2(μ-C5MeOQ)(NO3)2]. Single crystal X-ray analysis revealed that complex 1 contains dinuclear Cu(II) units with bridging methoxo groups. The ligand, C5MeOQ, takes on a bent conformation in order to connect to and complete the square planar coordination environment of both copper centers; and one of the two Cu(II) centers adopts a distorted square planar configuration as a result of the ligand conformation. The magnetic properties of complex 1 were investigated by variable-temperature magnetic susceptibility measurements in the 100–300 K range. Interestingly, the susceptibility data for complex 1 reveals that the compound is diamagnetic, suggesting the presence of very strong antiferromagnetic coupling interactions between the adjacent Cu(II) centers.

Four new one-dimensional coordination polymers containing the dimetal cluster Cu2(OAc)4 have been synthesized by reacting Cu(OAc)2 ⋅ H2O with two different N , N ′ -bidentate ligands. Reaction of the flexible ligand, 1,2-bis(4-pyridyl)ethane (L1), with the copper starting material produced two, co-crystallizing coordination polymers: catena-Poly[Cu2(OAc)4(L1)] ⋅ 2H2O (1) and catena-Poly[Cu2(OAc)4(L1)]. In the solid state, 1 (monoclinic, C2/c, a = 24.9471 ( 17 ) A , b = 13.3539 ( 9 ) A , c = 8.8050 ( 6 ) A , β = 93.6480 ( 10 ) ° , V = 2927.4 ( 3 ) A 3 , Z = 4 ) features linear chains which are organized into layers. These layers stack along the crystallographic c-axis forming small hexagonal channels occupied by the solvent of crystallization. Compound 2 (triclinic, P-1, a = 7.6263 ( 6 ) A , b = 8.5283 ( 6 ) A , c = 9.8633 ( 6 ) A , α = 74.1070 ( 10 ) ° , β = 68.2160 ( 10 ) ° , γ = 74.0090 ( 10 ) ° , V = 561.96 ( 7 ) A 3 , Z = 1 ) also features linear chains of the coordination polymer, but differs from 1 in that the chains are packed so as to leave no significant channels. Reaction of the rigid ligand, 1,4-bis(4-pyridyl)buta-1,3-diyne (L2), with the copper starting material also afforded two co-crystallizing coordination polymers: catena-Poly[Cu2(OAc)4(L2)] (3) and catena-Poly[Cu2(OAc)4(L2)] ⋅ solvents (4). 3 (monoclinic, P21/m, a = 9.8065 ( 9 ) A , b = 12.3793 ( 11 ) A , c = 9.9408 ( 9 ) A , β = 107.6009 ( 17 ) ° , V = 1150.29 ( 18 ) A 3 , Z = 2 ), like 2, features linear chains and contains no significant solvent accessible void space. 4 (monoclinic, C2/c, a = 28.9810 ( 16 ) A , b = 12.9301 ( 7 ) A , c = 8.6954 ( 5 ) A , β = 98.8010 ( 10 ) ° , V = 3220.0 ( 3 ) A 3 , Z = 4 ) also consists of linear chains of the coordination polymer. However, the overall topology of 4 is identical to that of 1, with the generated hexagonal channels containing crystallographically unidentifiable solvents of crystallization. Compounds 1 and 2 and compounds 3 and 4 are pairs of polymorphic coordination polymers neglecting the solvents of crystallization in 1 and 4. The compounds, which represent four new examples of coordination polymers containing dimetal units, have been characterized by IR, elemental analysis, and thermogravimetric analysis in addition to X-ray crystallography.

The new metal-organic framework materials, ZnF(Am{sub 2}TAZ).solvents and ZnF(TAZ).solvents (Am{sub 2}TAZ=3,5-diamino-1,2,4-triazole, TAZ=1,2,4-triazole), have been synthesized solvothermally and structurally characterized by either Rietveld refinement from powder XRD data or by single crystal X-ray diffraction. The three-dimensional structures of the compounds display open-ended, tubular channels, which are constituted of covalently bonded hexanuclear metallamacrocycles (Zn{sub 6}F{sub 6}(ligand){sub 6}). The tubular channels are subsequently covalently joined into a honeycomb-like hexagonal array to generate the three-dimensional porous framework. In the case of ZnF(Am{sub 2}TAZ).solvents, hydrophilic -NH{sub 2} groups point into the channels, effectively reducing their inner diameter relative to ZnF(TAZ).solvents. The present compounds are isostructural to one another and to the previously reported ZnF(AmTAZ).solvents (AmTAZ=3-amino-1,2,4-triazole), illustrative of the fact that the internal size and chemical properties of the framework may be altered by modification of the small, heterocyclic ligand. In addition to demonstrating the ability to modify the basic framework, ZnF(TAZ).solvents and ZnF(Am{sub 2}TAZ).solvents are two of the most thermally stable coordination frameworks known to date. - Graphical abstract: Top view of the open-ended, honeycomb tubular architecture of ZnF(Am{sub 2}TAZ)

The crystal structure of [Ru(2,2′-bipy) 3 ] 2 [Bi 4 I 16 ] (2,2′-bipy = 2,2′-bipyridine) contains the photochemically active coordination cation [Ru(2,2′-bipy) 3 ] 2+ and the large, polynuclear [Bi 4 I 16 ] 4− anion. [Bi 4 I 16 ] 4− consists of four edge-sharing BiI 6 octahedra and is derived from the neutral, semiconductor BiI 3 by uptake of I − . The title compound is a rare example of a mixed-metal halobismuthate material [crystal data C 60 H 48 Bi 4 I 16 N 12 Ru 2 : triclinic, P 1 ¯ , a = 12.2963(7) A, b = 14.0147(8) A, c = 14.7234(8) A, α = 70.1900(1)°, β = 69.2010(1)°, γ = 72.6570(1)°].

The new coordination polymer, {[Cd2(L1)3(sac)4]⋅2CH2Cl2}∞:, has been prepared from the reaction of 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L1) with [Cd(sac)2(H2O)4].2H2O(sac = saccharinate) in a methylene chloride/ethanol solvent mixture. The compound features a non-interpenetrating ladder motif constructed from Cd(L1)3 T-shaped units. The Cd atoms are coordinated to three nitrogen donor atoms from three L1 ligands and two nitrogen donor atoms from two saccharinate ligands in a rare, trigonal bipyramidal coordination environment. The compoundwas further characterized by IR spectroscopy and DTA/TGA. {[Cd2(L1)3(sac)4]⋅2CH2Cl2}∞: crystallizes in the triclinic space group P-1 with a = 10.8747(19)A, b = 12.626(2)A, c = 15.749(3)A, α = 111.839(3)°, β = 97.442(3)., and γ = 106.239(3)°

Using the new ligand, 2,2′-bis-(4-pyridylethynyl)tolane we have synthesized five new coordination polymers: HgBr2[2,2′-bis-(4-pyridylethynyl)tolane] (1), HgI2[2,2′-bis-(4-pyridylethynyl)tolane] (2), Ni(acetylacetonate)2[2,2′-bis-(4-pyridylethynyl)tolane] (3), Zn(acetylacetonate)2[2,2′-bis-(4-pyridylethynyl)tolane] (4), and Cu(hexafluoro acetylacetonate)2[2,2′-bis-(4-pyridylethynyl)tolane]⋅CHCl3 (5). 2,2′-Bis-(4-pyridyl ethynyl)tolane is a rigid ligand with a Z-shape that promotes the formation of zig-zag chains. Compounds 1– 5 were characterized by single crystal X-ray diffraction; and compounds 1– 3 were additionally characterized by IR, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic space group C2/c with a = 29.761(3) A, b = 5.0531(5) A, c = 16.7823(15) A, β = 104.090(2)∘, V = 2447.9(4) A3, Z = 4. Each mercury is bound to two tolane ligands and two bromine anions, resulting in a tetrahedral coordination environment. Compound 2 crystallizes in the monoclinic space group P2/c, with a = 20.3061(17) A, b = 5.6303(5) A, c = 24.5459(19) A, β = 110.338(2)∘, V = 2631.4(4) A3, Z = 4. Here also, each mercury is bound to two tolane ligands and two iodine anions in a tetrahedral coordination environment. The ligand orientation differs in compounds 1 and 2 being trans oriented in 1 and cis oriented in 2. Compound 3 crystallizes in the monoclinic space group P21/c with a = 14.5947(14) A, b = 6.3082(6) A, c = 18.3939(18) A, β = 112.112(2)∘, V = 1568.9(3) A3, Z = 2. Each nickel is bound to two tolane ligands and two bidentate AcAc anions, resulting in an octahedral coordination environment. Compound 4, which is isostructural with 3, also crystallizes in the monoclinic space group P21/c with a = 14.6990(9) A, b = 6.2724(4) A, c = 18.6433(11) A, β = 112.8610(10)∘, V = 1583.86(17) A3, Z = 2. Compound 5 crystallizes in the triclinic space group P-1 with a = 6.5487(4) A, b = 11.6471(7) A, c = 14.3225(9) A, α = 70.1360(10)∘, β = 89.3990(10)∘, γ = 88.7680(10)∘, V = 1027.18(11) A3, Z = 1. Each copper in 5 is bound to two tolane ligands and two bidentate hfAcAc anions, resulting in an octahedral coordination environment identical to that found in 3 and 4.

The synthesis and crystal structures of four mononuclear PtII homoleptic complexes with two thiacrown ligands are presented. The binding mode for both macrocycles to the platinum center contrasts with previous structural reports involving identical complex cations but differing anions or crystallization solvents. All three bis(1,4,7-trithiacyclononane(9S3))platinum(II) complexes (with tetrafluoroborate, hexafluorophosphate, and triflate as counterions) are centrosymmetric, with endodentate binding of the trithioether resulting in [S4 + S2] coordination. The PtII complex of 1,4,7,10,13,16-hexathiacyclooctadecane(18S6) shows an elongated square pyramidal structure with one exodentate sulfur in a [S4 + S1] mode. Our work illustrates how changes of counterion and solvent dramatically affect the crystal structures for such complexes, suggesting that packing forces are more important than ligand conformation in determining solid-state structures. In addition, the full spectroscopic and electrochemical properties of the complex [Pt(18S6)](BF4)2 are reported. The electronic spectrum shows a d−d transition near 430 nm, and an irreversible PtII/PtIII couple occurs at +564 mV vs. Fc/Fc+ in cyclic voltammetry. Both these data are consistent with other hexakis(thioether) PtII complexes. 13C NMR measurements show a non-fluxional 18S6 ligand in the complex while the platinum-195 NMR resonance at −4152 ppm indicates a mixed orientation of lone pair electrons on the sulfur donors. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The synthesis, spectroscopy, electrochemistry, and crystal structures of two new mononuclear homoleptic Pt(II) and Pd(II) complexes with the crown trithioether 1,5,9-trithiacyclododecane (12S3) are reported. In contrast to behavior with analogous smaller ring trithiacrowns, both metal complexes exhibit exodentate axial sulfur donors, a consequence of the preferred conformation of the 12S3 ligand. The lack of two axial metal-sulfur interactions correlates with the observed electronic spectroscopy and oxidative electrochemistry displayed by the complexes and contrasts with properties exhibited by complexes containing smaller polythioether macrocycles. The two complexes have electronic spectra dominated by charge transfer, not d-d bands and show no M 2 + /M 3 + couples. Both complexes show a fluxional 12S3 ligand in solution due to a 1,5-metallotropic shift, an uncommon observation of this particular type of intramolecular ligand exchange. The 1 9 5 Pt NMR chemical shift of -4201 ppm for [Pt(12S3) 2 ] 2 + is consistent with an alternating positioning of the four sulfur lone pairs on the coordinated thioethers. Although 12S3 is poorly pre-organized for facial complexation, its flexibility to position a sulfur in an exodentate fashion enables it to form stable complexes with d 8 metal ions such as Pt(II) and Pd(II).

A new microporous coordination polymer, [Co(saccharinate)2(L1)(H2O)2] n solvate, has been prepared from the reaction of the N,N′ bidentate ligand 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (L1) with [Co(saccharinate)2·4H2O]·2H2O in a methylene chloride/ethanol solvent mixture. The compound crystallizes in the triclinic system, space group P-1, with lattice parameters a = 7.6893(5) A, b = 11.0169(7) A, c = 11.2369(7) A, α = 66.2610(10)°, β = 74.4160(10)°, γ = 74.6740(10)°. The structure consists of one-dimensional chains composed of octahedrally coordinated Co(II) centers linked by L1. The packing of these chains, along with intrachain and interchain hydrogen bonds, generates a 3-D framework with infinite channels that are occupied by disordered guest molecules. The compound was further characterized by IR spectroscopy and DTA/TGA.

An effective solvothermal procedure has been developed to synthesize the new three-dimensional metal-organic framework, [ZnF(AmTAZ)].solvents, using either 3-amino-1,2,4-triazole (AmTAZ) or 3-amino-1,2,4-triazole-5-carboxylic acid (AmTAZAc) and a choice of several Zn(II) salts as starting materials. The three-dimensional structure displays open-ended, hollow nanotubular channels that are formed by hexanuclear metallamacrocyclic Zn(6)F(6)(AmTAZ)(6) rings. The framework integrity is maintained to 350 degrees C, at which point most of the guest solvent molecules have been removed, as evidenced by single-crystal X-ray analyses, (1)H solid-state NMR, and TGA measurements. At higher temperatures, the framework is converted either to zinc oxide (ZnO) when heated in air or to zinc cyanamide (ZnCN(2)) when heated in an inert atmosphere. In both cases, the as-grown, rodlike crystal shape is maintained during the solid-state transformation, suggesting a possible route for preparing one-dimensional crystalline nanomaterials.

The reactions of HgI(2) with the semirigid ditopic ligand 1,3-bis(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene (bbimms) afforded three new complexes, [Hg(2)(mu-I)(2)I(2)(bbimms)] (1), [Hg(2)I(4)(bbimms)(2)] (2), and catena-poly[HgI(2)(bbimms)] (3). The ligand and all complexes have been structurally characterized by single-crystal X-ray diffraction. 1 is a triply bridged dinuclear complex comprised of two Hg(II) ions, one bridging ligand, two bridging I(-) anions, and two terminal I(-) anions. 2 is a dinuclear metallamacrocycle comprised of two Hg(II) ions, two bridging ligands, and four terminal I(-) anions, while 3 is a helical chain with the repeating unit of HgI(2)(bbimms). 2 and 3 can be classified as supramolecular isomers, and both are related to the triply bridged precursor 1 via the addition of one more ligand in a ring-opening process.

The two-dimensional coordination polymer [Cu2i2(pyz)]n (where pyz = pyrazine) has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction analysis. [Cu2i2(pyz)]n crystallizes in the space group P\({\bar 1}\) with a = 4.1759(4) A, b = 7.1281(7) A, c = 8.1279(8) A, α = 109.607(2)○, β = 101.769(2)○, γ = 96.676(2)○, and Z = 1. The sheet-like polymer is characterized by infinite “stair step” [Cu2i2]n double chains connected in two dimensions through bridging pyrazine ligands. The coordination environment about each copper is approximately tetrahedral having three Cu–I bonds and a single Cu–N bond.

A new coordination polymer, catena-poly[Rh2(OAc)4(C27H15N3)]⋅2CH2Cl21 has been synthesized by self-assembly from Rh2(OAc)4 dimer units and the new ligand, 1,3,5-tris[(2-pyridyl)ethenyl]benzene 2. The compound was characterized by single crystal X-ray diffraction and was found to crystallize in the triclinic space group P-1, with a = 10.8206(9) A, b = 14.0331(12) A, c = 15.0901(12) A, α = 113.965(2)°, β = 100.250(2)°, γ = 90.462(2)°, and Z = 2. The one-dimensional polymer contains two crystallographically different Rh-dimer units, both located about crystallographic inversion centers. Each Rh2(OAc)4 unit connects in a trans fashion with the potentially tridentate ligand giving an overall 1:1 metal dimer-to-ligand ratio. This arrangement leaves a third nitrogen donor site on the ligand uncoordinated.

Hydrogen gas is produced photocatalytically using 470 nm light, PVP-coated carbon quantum dots (CQDs) as the photosensitizer, and nickel nanoparticles (NiNPs) as the catalyst. The effect of the amount of polyvinylpyrrolidone (PVP) on the ability of the CQD/NiNP composites to catalyze proton reduction was studied. A maximum of 330 mmols H2/g CQD is produced using 68 μg ml-1 of CQDs and 6 μg ml-1 of NiNPs, with activity persisting for 4 h when 20 wt%-PVP-coated CQDs were used. The H2 production quantum yield under these conditions is 6%. It was found that composites having higher weight percent PVP had decreased rates of H2 production, but increased duration. Increasing the weight percent of PVP coating also increases the fluorescence quantum yield of CQDs. Fluorescence quenching titrations reveal that H2 production could occur by either a reductive or oxidative quenching mechanism. The nanomaterials, prepared using simple methods, are used as the photosensitizer and catalyst in the proton reduction system that operates using visible light.

The polymeric title complex, [Zn(NO3)2(C24H20N8)(H2O)2]n, features distorted ZnN2O4 octa­hedra with each ZnII atom being located on an inversion center. Adjacent Zn ions are doubly bridged by two equivalent 1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene ligands to form linear chains.

The title compound, [Cu(C8H4F3O2S)2(C12H10N4)]n or [Cu(tta)2(L2)2]n (L2 = 1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene and tta = α-thenoyltrifluoro­acetonate), consists of undulating chains containing two crystallographically distinct CuII centers that are each located on inversion centers. Each CuII center exhibits distorted octa­hedral coordination provided by two pyridyl N atoms from two equivalent L2 ligands and four O atoms from two equivalent tta ligands. The chains inter­act through weak C—F⋯H—C contacts.

The new iodo­bismuthate compound (C13H11N2O)4[Bi6I22] has been synthesized solvothermally by reacting BiI3, Zn(NO3)2·6H2O and 4,5-diaza­fluoren-9-one in a water/ethanol solvent mixture. The asymmetric unit of the compound contains two independent [N-ethyl-4,5-dafo]+ cations and one-half of a centrosymmetric [Bi6I22]4− anion. The average terminal Bi—I, Bi—μ2-I and Bi—μ3-I bond lengths in the anion are 2.8923 (2), 3.1403 (2) and 3.3022 (2) A, respectively.

The title bis­muth-iodide compound, [Bi2I6(C12H8N2)2], has been synthesized solvothermally by reacting BiI3, Mn(CH3COO)2·4H2O, and 1,10-phenanthroline in an ethanol/water solvent mixture. The compound contains two bis­muth centers that are each coordinated by a phenanthroline ligand and two terminal iodide ligands, and the bis­muth centers are bridged via two additional iodide ligands to form a mol­ecular dimer. The asymmetric unit of the compound consists of one half of a single dimer mol­ecule located on a crystallographic inversion center.

In the one-dimensional title polymer, [Cu(C8H4F3O2S)2(C12H10N4)]n or [Cu(L)2(tta)2] [tta is α-thenoyl­trifluoro­acetonato and L is 1,4-bis­(4-pyrid­yl)-2,3-diaza-1,3-butadiene], Cu2+ lies on a center of inversion. It is axially coordinated by two pyridyl N atoms from two different L ligands and equatorially coordinated by four O atoms from two chelating tta ligands. The ligand L propagates the one-dimensional chain structure by serving as a bridging ligand between two Cu octa­hedra via Cu—N coordinate bonds.

The asymmetric unit of the title compound, [Co(C2H8N2)3][Bi2I9], crystallizes in the ortho­rhom­bic space group Cmc21. The asymmetric unit contains half of a [Co(en)3]3+ cation (en is ethyl­enediamine) and half of a [Bi2I9]3− anion. Both species are located on mirror planes, requiring the [Co(en)3]3+ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol–water solvent mixture using rac-[Co(en)3]I3 and bis­muth triiodide as starting materials. The compound is a rare example of a mixed-metal halobismuthate material.