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Via flux-assisted synthesis, we discovered three novel salt-inclusion materials, t-[Na2Cl]GaS2, o-[Na2Cl0.9I0.1]GaSe2, and t-[Na2Cl0.9I0.1]GaSe2, and two new selenides, Na2GaSe3 and Na4Ga2Se5, by changing the flux from NaCl/NaI to NaBr/NaI, respectively.

Single crystals of new rubidium rare earth thiophosphates with the formulas Rb3Ln(PS4)2 (Ln = La, Ce, Pr), Rb3−xNaxLn(PS4)2 (Ln = Ce, Pr; x = 0.50, 0.55), and RbEuPS4 were crystallized out of a molten RbCl flux. The compounds Rb3Ln(PS4)2 (Ln = La, Ce, Pr) and Rb3−xNaxLn(PS4)2 (Ln = Ce, Pr; x = 0.50, 0.55) both crystallize in the monoclinic crystal system adopting the space groups P21 and P21/c, respectively, while RbEuPS4 crystallizes in the orthorhombic crystal system adopting the space group Pnma. A survey of all known rubidium rare earth thiophosphates grown using an alkali halide flux revealed trends suggesting that the Rb3Ln(PS4)2 and Rb3−xNaxLn(PS4)2 families of compounds can be actively targeted over a wide range of temperatures by employing RbCl as at least a component of the flux. Fluorescence measurements were performed on all compounds obtained, revealing resolved f–f transitions in Rb3Pr(PS4)2 and Rb2.45(2)Na0.55(2)Pr(PS4)2 and only single broad emission peaks for Rb3Ce(PS4)2 and Rb2.50(6)Na0.50(6)Ce(PS4)2, behavior characteristic for cerium(III) compounds.

Two series of new lanthanide thiophosphates with partial Ca occupancy of the Ln sites, Cs0.3(Ca0.3Ln0.7)PS4 (Ln = Ce, Pr, Nd, Sm, Gd, Tb, and Dy) and Cs0.5(Ca0.5Ln0.5)PS4 (Ln = Pr, Nd, Sm, Gd, and Tb), were synthesized using a CsI flux and structurally characterized. The first series with an idealized formula of Cs0.3(Ca0.3Ln0.7)PS4 crystallizes in the Rm space group and belongs to a new structure type that consists of a channel containing [(Ca0.3Ln0.7)PS4]0.3− framework, where the channels are occupied by severely disordered Cs+ cations. A second new series with formula Cs0.5(Ca0.5Ln0.5)PS4 crystallizes in the monoclinic C2/c space group and exhibits a layered structure consisting of [(Ca0.5Ln0.5)PS4]0.5− layers with Cs+ cations located between the layers for charge balance. Together with the parent structure type, LnPS4, these three structure types illustrate how the LnPS4 structure changes with Cs+ cation incorporation, reducing its dimensionality from 3D to 2D. The magnetic properties of Cs0.3[(Ca0.3Ce0.7)PS4] and Cs0.3[(Ca0.3Pr0.7)PS4] were studied and revealed no magnetic transition down to 2 K.

A series of rubidium rare earth thiophosphates with the formula Rb4Ln2(P2S6)(PS4)2 (Ln = La, Ce, Pr, Nd, Sm, and Gd) were synthesized using the high temperature molten flux crystal growth method utilizing a RbBr flux. Single crystals of all title compounds, as well as phase pure powders of the La-, Ce-, and Sm-containing compositions, were obtained. Single crystals of the title compounds were characterized by single crystal and powder X-ray diffraction for structure and phase identification. Rb4Ln2(P2S6)(PS4)2 crystallizes in the monoclinic crystal system adopting the P21/n space group for the large rare earths (Ln = La, Ce, Pr) and the C2/c space group for the smaller rare earths (Ln = Nd, Sm, Gd). This Rb4Ln2(P2S6)(PS4)2 series is a rare example of thiophosphates containing both tetrahedral [PVS4]3- and dimeric [PIV2S6]4- thiophosphate units that, in this structural family, link corrugated rare earth sulfide chains into sheets. The band gaps of the materials were determined from UV-Vis data and the fluorescence spectrum of Rb4Ce2(P2S6)(PS4)2 was collected. Optical band gaps were estimated to be 2.9 and 2.4 for the Nd and Sm analogues, respectively.

The molten flux synthesis of a uranium gallophosphate and a uranium gallate, Cs4[UO2Ga2(PO4)4] (1) and Cs2UO2Ga2O5 (2), and four uranium phosphates, [Rb2Rb3.93Cl0.93][(UO2)5(PO4)5] (3), Rb11[(UO2)8(PO4)9] (4), Rb7.6[(UO2)8O8.6F0.4(PO4)2] (5), and Rb6[(UO2)5O2(PO4)4] (6), is reported. A systematic exploration of the UF4–GaPO4–ACl (A = Cs, Rb) phase space resulted in the synthesis of targeted Cs4[UO2Ga2(PO4)4] (1) and Cs2UO2Ga2O5 (2), which are gallium analogs of the previously reported aluminates, Cs4[UO2Al2(PO4)4] and Cs2UO2Al2O5. The exploration of this phase space simultaneously led to the synthesis and characterization of four new uranium phosphate phases: [Rb2Rb3.93Cl0.93][(UO2)5(PO4)5] (3), a salt inclusion material, and Rb11[(UO2)8(PO4)9] (4), both of which have complex 3D, porous, framework structures, and Rb7.6[(UO2)8O8.6F0.4(PO4)2] (5) and Rb6[(UO2)5O2(PO4)4] (6), both of which are layered structures related to the U3O8 topology. Fluorescence spectroscopy data are reported for all the compositions and are found to be typical for uranyl compounds.

The stability of the novel Pu(iv) silicate, Cs2PuSi6O15, was predicted from a combination of crystal chemical reasoning and DFT calculations and confirmed by its synthesis via flux crystal growth. Formation enthalpies of the A2MSi6O15 (A = Na-Cs; M = Ce, Th, U-Pu) compositional family were calculated and indicated the Cs-containing phases should preferentially form in the Cmc21 structure type, consistent with previous experimental findings and the novel phases produced in this work, Cs2PuSi6O15 and Cs2CeSi6O15. The formation enthalpies of a second set of compositions, A2MSi3O9, were also calculated and a comparison between the two compositional families correctly predicted A2MSi6O15 to be on average more stable than A2MSi3O9.

A series of new Ce(IV) based fluorides with two different compositions, Cs2MCe3F16 (M = Ni2+, Co2+, Mn2+, and Zn2+) and Na3MCe6F30 (M = Al3+, Ga3+, Fe3+, and Cr3+) were synthesized as high quality single crystals via a mild hydrothermal route. The compounds with the composition Cs2MCe3F16 (M = Ni2+, Co2+, Mn2+, and Zn2+) crystallize in the hexagonal crystal system with space group P63/mmc and are isotypic with the uranium analogs, whereas the Na3MCe6F30 (M = Al3+, Ga3+, Fe3+, and Cr3+) compounds crystallize in the trigonal space group Pc1 and are isotypic with the uranium and thorium analogs NaxMM′6F30 (M′ = Th, U). The Cs2MCe3F16 compounds exhibit a complex 3D crystal structure constructed of edge-sharing cerium trimers, in which all three Ce atoms share a common μ3-F unit. The Na3MCe6F30 compounds are constructed of edge- and vertex-sharing cerium polyhedra connected to each other to form Ce6F306− framework, which can accommodate only relatively smaller trivalent cations (M3+ = Al3+, Ga3+, Fe3+, and Cr3+) as compared to uranium and thorium analogs. Magnetic susceptibility measurements were carried out on the samples of Cs2MCe3F16 (M = Ni2+ and Co2+), which exhibit paramagnetic behavior.

Four new cesium-containing cobalt oxide complexes were reported. Cs(Co0.5Si0.5)SiO4 (1), Cs1.29(5)Co0.69(5)Ge1.81(5)O5 (2), and its ordered analogue Cs2CoGe4O10 (3) were synthesized using a mixed CsCl–CsF flux at 850 °C or 900 °C. The structure of (1) closely resembles that of known zeolite and feldspar structures, and (1) crystallizes in the noncentrosymmetric monoclinic space group Im with lattice parameters of a = 8.9926(4) A, b = 5.4599(2) A, c = 9.3958(6) A, and β = 91.5928(18)°. Complexes (2) and (3) crystallize in the same new structure with a highly porous three-dimensional framework in the tetragonal space group I with lattice parameters of a = 7.4239(14) A and c = 13.169(3) A for (2) and a = 7.3540(6) A and c = 13.1122(11) A for (3). The formation of (2) vs. (3) can be controlled based on slight variations in the quantities of the starting materials. Single-crystal-to-single-crystal ion exchange of (1) in a molten RbNO3 bath resulted in 14% Cs exchange with Rb, affording the composition Cs0.86Rb0.14(Co0.5Si0.5)SiO4 (4). First-principles density functional theory calculations were performed to elucidate the electronic and magnetic properties and stabilities of (1) and (3) at 0 K.

Single crystals of two new germanates, [(Rb6F)(Rb4F)][Ge14O32] and [(Rb6F)(Rb3.1Co0.9F0.96)][Co3.8Ge10.2O30F2], were synthesized via high temperature RbCl/RbF flux growth. Both compounds crystallize in the cubic space group F3m and possess the germanium framework of the previously reported salt inclusion material (SIM), [(Cs6F)(Cs3AgF)][Ge14O32], related to the Ge7O16 zeolitic family. These materials demonstrate the ability to accommodate a variety of salt-inclusions, and exhibit chemical flexibility enabling modifications of the framework through incorporation of Co. Alteration of the salt-inclusion led to intrinsic luminescence of [(Rb6F)(Rb4F)][Ge14O32] while modification of the framework resulted in an unanticipated Rb/Co salt/inclusion in [(Rb6F)(Rb3.1Co0.9F0.96)][Co3.8Ge10.2O30F2]. Fluorescence measurements were performed on [(Rb6F)(Rb4F)][Ge14O32]. First-principles calculations in the form of density functional theory (DFT) were performed for [(Rb6F)(Rb3.1Co0.9F0.96)][Co3.8Ge10.2O30F2] to elucidate its electronic and magnetic properties, and stability at 0 K.

A new self-activated X-ray scintillator, BaWO2F4, with an excellent photoluminescence quantum efficiency is reported. Hydrothermally grown single crystals, space group P2/n, exhibit a 3D framework structure containing isolated WO2F4 octahedra. BaWO2F4 exhibits green emission under UV light with a high quantum yield of 53% and scintillates when exposed to X-rays(Cu).

Although Zn-based binary semiconductors such as ZnO and ZnS are photocatalytically unstable toward water oxidation, we found that mixed-anionization successfully addressed this issue. This report shows that an oxysulfide SrZn2S2O functions as a photocatalyst to reduce and oxidize water under band-gap irradiation without noticeable decomposition of the material.

This frontier article focuses on the use of flux crystal growth for the preparation of new actinide containing materials, reviews the history of flux crystal growth of uranium containing phases, and highlights the recent advances in the field. Specifically, we discuss how recent developments in f-element materials, fueled by accelerated materials discovery via crystal growth, have led to the synthesis and characterization of new families of complex uranium containing oxides, namely alkali/alkaline uranates, oxychlorides, oxychalcogenides, tellurites, molybdates, tungstates, chromates, phosphates, arsenates, vanadates, niobates, silicates, germanates, and borates. An overview of flux crystal growth is presented and specific crystal growth approaches are described with an emphasis on how and why they - versus some other method - are used and how they enable the preparation of specific classes of new materials.

The novel phases Rb4NaU3O12−xFx (1), K4NaU3O12−xFx (2), and Rb2.1K1.9KU3O12−xFx (3) were synthesized by molten flux methods using mixed alkali fluoride melts. The oxyfluorides crystallize in the cubic space group Imm with a lattice parameters of 8.7472(2) A, 8.6264(2) A, and 8.8390(3) A, respectively. All three structures crystallize in a cubic perovskite structure, ABO3 (A4BB′3O12), where the A site is fully occupied by an alkali cation, and the B site is shared by the remaining smaller alkali cation and uranium in an ordered fashion such that the alkali cation on the B site is surrounded by square uranyl bipyramids. The structures were characterized by single crystal X-ray diffraction, energy dispersive spectroscopy, X-ray absorption near edge structure spectroscopy, X-ray photoelectron spectroscopy, magnetic susceptibility measurements, DFT calculations, thermogravimetric analysis, and UV-vis spectroscopy, all of which support the presence of U(V) in the three new materials.

Mixed-valent uranium(iv,v) and (v,vi) phases represent a unique subset of known uranium compounds. Efforts to develop our current understanding of these materials have pointed to hydrothermal methods as effective preparative techniques. Herein we report the successful use of moderate supercritical conditions for the synthesis of five new U(v) containing phases.

High quality single crystals of the monoclinic phase K5U5O17(OH) were synthesized via a hydrothermal method utilizing the supercritical regime of water. The structure of K5U5O17(OH) is isotypic with the Na phase, Na5U5O17(OH), however crystallizes in a slightly different space group due to size effects. K5U5O17(OH) has the same sheet-anion structure as the Na analog, whose topology is analyzed here for the first time. K5U5O17(OH) shows fluorescence typical for uranyl species.

Single crystals of five transition metal uranium fluorides were obtained via the use of a mild hydrothermal route. Uranyl acetate was used as both the uranium source and the reducing agent for an in situ reduction of U(VI) to U(IV). The synthesized materials are present as both two- and three-dimensional structures and contain uranium in 9-fold coordination environments. Magnetic susceptibility measurements indicate that the reported materials remain paramagnetic down to 2 K, with no evidence for the existence of long-range magnetic ordering. Thermogravimetric analysis studies of the reported materials are also presented.

Two polymorphs of K3YSi2O7, crystallizing in the space groups P63/mmc (1) and P63/mcm (2) can be synthesized by high temperature flux crystal growth. The flux growth conditions can be fine-tuned to yield a phase pure sample of polymorph (2), however, not of polymorph (1), which always co-crystallizes with polymorph (2). Polymorph (2) was found to exhibit intrinsic bluish-white light emission. Further studies determined that doping europium and dysprosium onto the yttrium site of this polymorph could readily tune the luminescence, with the purest white light emission found for the K3YSi2O7: 10% Dy, 0.1% Eu composition (K3Y0.899Dy0.1Eu0.001Si2O7) (2-Dy,Eu).

Single crystals of K4CaUSi4O14 have been grown from a eutectic CaF2–KF flux. K4CaUSi4O14 crystallizes in a new structure which exhibits a 49-fold superstructure believed to be due to a modulation of the uranium and silicon polyhedra. We report the sub-cell of the structure which adopts the tetragonal space group Pn2 with lattice parameters a = 9.2862(2) A, c = 8.3796(4) A, and V = 722.60(5) A3. K4CaUSi4O14 is a member of a structural family related to the mineral fresnoite which we describe here. Finally, we report UV-vis absorbance and SHG measurements on the compound, which is non-centrosymmetric.

Single crystals of Na5RE4(OH)[SiO4]4 (RE = Pr, Nd, Sm, Eu, Tb–Yb, Y) were grown using the hydroflux synthetic method. All compositions adopt the tetragonal I space group with lattice parameter ranges of a = 11.5275(4)–12.0588(3) A and c = 5.3951(4)–5.4846(13) A. Intense photoluminescent properties were observed for Na5Eu4(OH)[SiO4]4, Na5Gd4(OH)[SiO4]4, and Na5Tb4(OH)[SiO4]4. The magnetic susceptibility was measured for the magnetic rare earth containing compositions, where the terbium analogue displayed antiferromagnetic order at T = 2.8 K.

Four new vanadium oxyfluorides (VOFs), Sr4V3O5F13 (1), Pb7V4O8F18 (2), Pb2VO2F5 (3), and Pb2VOF6 (4), have been synthesized under mild hydrothermal conditions. The choice of starting reagents, AF2 or A(CH3CO2)2·xH2O (A = Pb, alkaline earth), determined the oxidation states of vanadium in the final products. The reaction of V2O5 with AF2 leads, consistently, to the formation of V(V) compounds, while the use of A(CH3CO2)2·xH2O results in V(IV) containing compounds, suggesting that the acetate species behaves as an effective mild reducing agent. The crystal structures, characterized by single crystal X-ray diffraction, revealed that the compounds exhibit various anionic VOF building blocks, including dimeric and trinuclear units, as well as one-dimensional chains. All compounds contain fluorine atoms that are not bonded to the vanadium atoms, which are located between two-dimensional layers consisting of corner- or edge-shared FA3 or FA4 polyhedra that separate the vanadium containing building blocks. The magnetic susceptibility data for 4 were measured as a function of temperature, yielding an effective magnetic moment of 1.72 μB that confirms the presence of V(IV). UV-vis reflectance and thermal properties were also characterized.

Crystals of Na5RE4F[SiO4]4 (RE = Pr, Nd, Sm–Tm) and K5Pr4F[SiO4]4 were grown using a fluoride flux synthetic technique. All compositions crystallize in the tetragonal space group I with lattice parameter ranges of a = 11.5094(2)–12.3745(2) A and c = 5.37000(10)–5.5011(2) A. Antiferromagnetic ordering is observed for Na5RE4F[SiO4]4 (RE = Tb, Dy), second harmonic generation for Na5RE4F[SiO4]4 (RE = Pr, Sm–Ho), and intense optical properties and fluorescence quantum yield for Na5RE4F[SiO4]4 (RE = Eu, Gd, Tb). The crystal structures and physical property measurements are discussed.

Single crystals of Cs2.2U5O16 and Cs2U4O13 have been synthesized from a CsCl flux with the ramp rate controlling the formation of fully oxidized Cs2U4O13versus partially reduced Cs2.2U5O16. Their structures have been determined by single crystal X-ray diffraction. Cs2.2U5O16 crystallizes in the monoclinic space group C2/m with lattice parameters a = 13.4160(5) A, b = 15.5089(6) A, c = 7.9723(3) A, and β = 92.7120(10)° and Cs2U4O13 crystallizes in the orthorhombic space group Ccmm with lattice parameters a = 13.5031(6) A, b = 15.4048(7) A, c = 39.5680(17) A. The two compounds contain related uranium frameworks with disordered Cs atoms within the channels. Both structures contain multiple cation–cation interactions, CCIs, which arise due to the three dimensional nature of the framework. Magnetic properties are reported for Cs2.2U5O16, which contains mixed valent U.

Single crystals of five new alkali metal uranium oxychlorides, K4U5O16Cl2, Rb4U5O16Cl2, Cs5U7O22Cl3, RbUO3Cl, and CsUO3Cl, have been grown from molten chloride fluxes and structurally characterized by single crystal X-ray diffraction. All of the materials are monoclinic. The first three crystallize in the space group P21/n and exhibit a 2D layered structure with a novel layer topology, consisting of UO6, UO7, and UO4Cl2 polyhedra and cation–cation interactions (CCIs) within the plane of the uranyl sheet. A general cation–cation classification scheme is presented. RbUO3Cl and CsUO3Cl crystallize in the space group P21/m and exhibit 1D zipper-like chains of UO5Cl2 polyhedra. The lattice parameters of the new oxychlorides are: K4U5O16Cl2, a = 9.9574(4) A, b = 6.9766(3) A, c = 14.3920(6) A, and β = 105.7690(10)°; Rb4U5O16Cl2, a = 10.2164(4) A, b = 7.0160(3) A, c = 14.4930(5) A, and β = 103.8290(10)°; Cs5U7O22Cl3, a = 10.6214(5) A, b = 18.1071(8) A, c = 16.0857(7) A, and β = 102.9850(10)°; RbUO3Cl, a = 7.3602(6) A, b = 4.1127(3) A, c = 8.5556(7) A, and β = 104.602(2)°; CsUO3Cl, a = 7.7768(4) A, b = 4.1245(2) A, c = 8.7701(5) A, and β = 105.4680(10)°. The materials were further characterized by UV-vis reflectance spectroscopy and fluorescence spectroscopy.

Crystallographic structural changes were investigated for Sr2Fe1.5Mo0.5O6−δ, an electrode material for symmetric solid oxide fuel cells. The samples of this material were heated and cooled in wet hydrogen and wet oxygen atmospheres, to simulate the reducing and oxidizing conditions experienced under actual fuel cell operating conditions, and their structures and oxygen contents were determined using in situ powder neutron diffraction. The existence of a reversible tetragonal to cubic phase transition was established to occur between room temperature and 400 °C, both on heating and cooling in either oxygen or hydrogen. The oxygen content reaches a low value of 5.50(2) at 850 °C in wet hydrogen. Excellent correlations are observed between the oxygen content of the structure and the conductivities reported in the literature.

The ability to synthesize new complex oxide materials that belong to any of the large number of known oxide structural families relies typically on a general understanding of the relationship between the specific structure type and the chemical composition of its members. However, before one can create such a structure-composition relationship that enables the synthesis of new members, one needs structural information about a sizable number of existing compositions belonging to this structural family, somewhat of a “chicken or the egg” problem. In this Highlight we will use one family of oxides, specifically oxides related to the hexagonal perovskite structure, to illustrate how exploratory crystal growth methods have been used successfully to synthesize enough diverse compositions to enable the formulation of a general structural description. Furthermore, by now it appears that enough members with different compositions have been synthesized so that one can attempt to create a structure-composition relationship that has predictive powers.

Two new 3D framework materials containing Bi2O2 layers and Bi4O3 chains have been obtained hydrothermally via the reactions between bismuth nitrate with terephthalic acid (TA) and bismuth nitrate with nitro-terephthalic acid (NO2TA), respectively. The Bi2O2 layers are connected into a 3D structure via bridging TA ligands to form Bi2O2(TA) (1), while the novel Bi4O3 chains are connected into a 3D framework via linking NO2TA ligands to form Bi4O3(NO2TA)3(H2O)·(H2O)0.68 (2). Compound 1 exhibits photoluminescence that is red-shifted compared to that of the TA ligand, while the photoluminescence is quenched in both compound 2 and the NO2TA ligand.

Four new inorganic–organic polymeric materials have been synthesized by reacting the metal containing building block, Cu(pyzca)2, with cadmium chloride. All resulting polymers have both metals incorporated in the structure and display a variety of structural motifs, ranging from one-dimensional chains to complicated three-dimensional networks. The first compound, [Cu(Pyzca)2(H2O)CdCl2(H2O)·H2O]n (1) is a one-dimensional double chain. The next two compounds, [Cu(Pyzca)2(H2O)2Cd2Cl4(H2O)2]n (2) and [Cu(Pyzca)2(H2O)Cd2Cl4(H2O)2·3H2O]n (3), assemble in a two-dimensional brick-wall network, while the fourth, [Cu(Pyzca)2Cd2Cl4]n (4), features an intricate three-dimensional network. Synthesis, X-ray structure determinations, and the influence of water molecules coordinated to the copper centers on the coordination geometry and overall extended structure are discussed.

Two new hydrogen-bonded coordination polymers have been prepared using the transition metal nitrate hydrates Cd(NO3)2·4H2O and Co(NO3)2·6H2O in combination with the organic bidentate ligand 4,4′-bipyridine: Cd2(H2O)4(bipy)5(NO3)2(PF6)2 (1) (bipy = 4,4′-bipyridine) and [Co(H2O)4(bipy)][PF6]2·3bipy (2). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. Compound 1 shows a novel hydrogen bonded brick wall motif assembled from unprecedented dimeric “H-shaped” [Cd2(bipy)5] building blocks via a new complementary binary hydrogen bonding bridge. Compound 2 forms a novel three-dimensional network based on [Co(H2O)4(bipy)]n linear polymer chains which are cross-linked to each other by a new type of Co–H2O(2)⋯bipy⋯H2O(1)⋯bipy⋯H2O(1)⋯bipy⋯H2O(2)–Co hydrogen bonding linkage.

Donor and acceptor co-doped SrTiO3 materials have shown interesting features in their conductivity and reducibility. In this work, 10 mol% Na+ or K+ as acceptor dopants have been introduced into the A-site of donor-doped strontium titanate, SrTi0.8Nb0.2O3, and the doping impact on their properties has been studied. By doping with Na or K, the sinterability of SrTi0.8Nb0.2O3 in reducing atmospheres has been improved. Na0.1Sr0.9Ti0.8Nb0.2O3 and K0.1Sr0.9Ti0.8Nb0.2O3 show metallic conduction behavior after being sintered at 1400 °C in 5% H2/N2. Electrical conductivity reaches 1180 S cm−1 at 400 °C and 272 S cm−1 at 800 °C for K0.1Sr0.9Ti0.8Nb0.2O3, which is higher than that of Sr0.99Ti0.8Nb0.2O3 prepared under similar conditions, indicating the improved reducibility of acceptor doped SrTi0.8Nb0.2O3. Such improvement may be attributed to the improved oxide ionic conductivity and cation mobility at high temperatures. Reduced polarization resistance is also observed using Na0.1Sr0.9Ti0.8Nb0.2O3 and K0.1Sr0.9Ti0.8Nb0.2O3 as anodes on YSZ electrolytes, suggesting improved catalytic activity by Na/K-doping.

Molecular ladders [Co(2)(nbpy4)(3)(NO(3))(4)]*solvents and [Cd(2)(nbpy4)(3)(NO(3))(4)](nbpy4 =N,N'-bis-(4-pyridinylmethylene)-1,5-naphthalenediamine) were synthesized via self-assembly; the former is a large, simple, noninterpenetrated 1D ladder that contains guest solvent molecules between the rungs, while the latter exists as 1D ladders in a rare four-fold interlocked 3D structure.

Self-assembly of HgI2 with a semirigid ditopic ‘Z’ type ligand affords the zigzag chains that interweave into a clothlike 2D network in a ‘two-over/two-under’ (2O/2U) fashion.

Tobacco mosaic virus (TMV) was electrospun with polyvinyl alcohol (PVA) into continuous TMV–PVA composite nanofibers to form a biodegradable nonwoven fibrous mat as an extracellular matrix (ECM) mimetic. Morphological characterizations by electron microscopy showed that the addition of varying amounts of TMV resulted in homogeneous nanofibers without phase separation and did not change the diameter of the composite nanofibers. The orientation of TMV in as-spun fibers could be readily controlled and post-processing of the nonwoven TMV–PVA mat significantly improved its water resistance. In addition, tensile tests were performed on individual nanofibers, which revealed that the TMV–PVA composite nanofibers achieved a comparable Young's modulus as PVA nanofibers. Since the modification of TMV is readily achieved via genetic or chemical methods, this process offers a facile way to incorporate a variety of functionalities into polymer nanofibers. As a demonstration of its potential as ECM mimetic, a mutant TMV containing RGD peptide was co-spun with PVA and the resulting fibrous substrates were used to promote cell growth.

Reaction of the new ligand 1,2-dimethoxy-4,5-bis(2-pyridylethynyl)benzene with different metal centers under similar reaction conditions led to three distinct structure formation processes: molecular ring closure, dimerization, and polymer formation.

Synthesis of poly(p-phenyleneethynylene)s (PPEs) containing 1,5-diethynyl-3,7-di-tert-butylnaphthalene leads to novel phenylene-naphthylene-ethynylene copolymers which show strong blue luminescence in the solid state.

A new mixed-metal compound, [Co(phen3)]2[Cu11I15] (phen = 1,10-phenanthroline), containing the two novel copper(I) iodide anionic clusters [Cu10I15]5− and [Cu12I15]3−, has been synthesized solvothermally and structurally characterized by single crystal X-ray diffraction. The synthesis and structures of the two clusters are presented and the extensive edge-to-face and offset face-to-face interactions between the [Co(phen3)]2+ cations are described.

This Dalton Perspective summarizes the rich structural diversity in coordination polymers that utilize pyrazine-2-carboxylate (pca) as the linking ligand. Pyrazine-2-carboxylate has two donor groups in the form of ring nitrogens and carboxylato oxygens. This dual functionality imparts this ligand with unique and reliable networking abilities described herein. Preceding the structural details of pca based coordination polymers is a brief examination of the separate components (organic and inorganic) and the syntheses of these hybrid materials.