Unusual Effects of the Metal Center Coordination Mode on the Photophysical Behavior of the Rhenium(I) and Rhenium(I)-Iridium(III) Complexes.

Binuclear transition-metal complexes based on conjugated systems containing coordinating functions are potentially suitable for a wide range of applications, including light-emitting materials, sensors, light-harvesting systems, photocatalysts, etc., due to energy-transfer processes between chromophore centers. Herein we report on the synthesis, characterization, photophysical, and theoretical studies of relatively rare rhenium(I) and rhenium(I)-iridium(III) dyads prepared by using the nonsymmetrical polytopic ligands (NN2 and NN3) with the strongly conjugated phenanthroline and imidazole-quinoline/pyridine coordinating fragments. Availability of these different diimine chelating functions and targeted synthetic procedures allowed one to obtain a series of mononuclear (Re and Ir) and binuclear (Re-Re and Re-Ir) metal complexes with various modes of {Re(CO)3Cl} and {Ir(NC)2} metal fragment coordination. The obtained compounds were characterized by 1D 1H and 2D (COSY and NOESY) NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray diffraction crystallography. The photophysical study of the complexes (absorption, excitation and emission spectra, quantum yields, and excited-state lifetimes) showed that their emission parameters display strong dependence on the manner of metal center coordination to the diimine bidentate functions. The mononuclear complexes with an unoccupied imidazole-quinoline/pyridine fragment [Re(NN2), Re(NN3), and Ir(NC2)2(NN2)] or those containing a coordinated {Ir(NC)2} fragment in this position [Ir(NC2)2(NN1) and Re(NN2)Ir(NC1)2-Re(NN2)Ir(NC4)2] exhibit moderate-to-intense phosphorescence (quantum yields vary from 3% to 56% in a degassed solution), whereas the complexes containing a {Re(CO)3Cl} moiety in the imidazole-quinoline/pyridine position [Re2(NN2), Re2(NN3), and Ir(NC2)2(NN2)Re] demonstrate a strong reduction in the phosphorescence efficiency with a quantum yield of ≪0.1%. Quenching of the phosphorescence in the latter types of emitters is discussed in terms of a strong decrease in the radiative rate constants for these complexes compared to their analogues mentioned above, while the nonradiative constants remain nearly unchanged. Theoretical density functional theory (DFT) and time-dependent DFT (TD DFT) calculations, including evaluation of the radiative rate constants for the couple of structurally analogous complexes with and without a {Re(CO)3Cl} moiety coordinated to the imidazole-quinoline/pyridine chelating function, confirmed the observed trend in the variation of the emission intensity.

2 + 1 Tricarbonyl Complexes of Technetium(I) with a Combination of N,N-Bidentate Ligands and Ethyl Isocyanoacetate: How Strong Is the Interfering Effect of Chloride Ions on Their Formation?

Technetium(I) 2 + 1 tricarbonyl complexes with a combination of N,N-bidentate ligands (2,2'-bipyridine, bipy; 1,10-phenanthroline, phen) and ethyl isocyanoacetate were prepared and characterized by NMR, IR, UV/visible, and luminescence spectroscopies and by high-performance liquid chromatography (HPLC). The crystal structures of [99Tc(CO)3(bipy)(CNCH2COOEt)](ClO4) (in the form of a solvate with 0.5CH2Cl2) and [99Tc(CO)3(phen)(CNCH2COOEt)](ClO4) (in the form of an adduct with an outer-sphere phen molecule) were determined by single-crystal X-ray diffraction. To evaluate the interfering effect of chloride ions on the formation of the 2 + 1 complexes, the kinetics of the replacement of labile monodentate ligand X in the complexes [MX(CO)3(N∧N)] (M = Re, 99Tc; N∧N = bipy, phen; X = Cl-, ClO4-) by CNCH2COOEt in ethanol were compared. The 99Tc bipy complexes with X = ClO4- (according to the IR data, perchlorate anion in ethanol is displaced from the coordination sphere by the solvent molecule) and X = Cl- are characterized by close ligand replacement rates. In the case of the 99Tc complexes with phen and Re complexes with both phen and bipy, the chloride complexes are appreciably less reactive than the chloride-free complexes. The technetium complexes are considerably more reactive in ligand replacement than their rhenium analogues. In the chloride-containing medium (saline), the complex [99mTc(CO)3(bipy)(CNCH2COOEt)]+ can be prepared under the conditions acceptable for nuclear medical applications, although higher isonitrile concentrations are required as compared to the chloride-free system.

Organically Templated Uranyl Sulfates and Selenates: Structural Complexity and Crystal Chemical Restrictions for Isotypic Compounds Formation.

This paper reviews the state of the art in the structural chemistry of organically templated uranyl sulfates and selenates, which are considered as the most representative groups of U-bearing synthetic compounds. In total, there are 194 compounds known for both groups, the crystal structures of which include 84 various organic molecules. Structural studies and topological analysis clearly indicate complex crystal chemical limitations in terms of the isomorphic substitution implementation, since the existence of isotypic phases has to date been confirmed only for 24 compounds out of 194, which is slightly above 12%. The structural architecture of the entire compound depends on the combination of the organic and oxyanion parts, changes in which are sometimes realized even while maintaining the topology of the U-bearing complex. An increase in the size of the hydrocarbon part and number of charge functional groups of the organic cation leads to the formation of rare and more complex topologies. In addition, the crystal structures of two novel uranyl sulfates and one uranyl selenate, templated by isopropylammonium cations, are reported.

Is It Possible to Obtain a Product of the Desired Configuration from a Single Knoevenagel Condensation? Isomerization vs. Stereodefined Synthesis.

The biological activity of compounds directly depends on the three-dimensional arrangement of affinity fragments since a high degree of pharmacophore compliance with the binding site is required. 3-Benzylidene oxindoles are privileged structures due to their wide spectrum of biological activity, synthetic availability, and ease of modification. In particular, both kinase inhibitors and kinase activators can be found among 3-benzylidene oxindoles. In this work, we studied model compounds obtained via oxindole condensation with aldehydes and alkylphenones. These condensation products can exist in the form of E- and Z-isomers and also undergo isomerization in solutions. The factors causing isomeric transformation of these compounds were established. Comparative kinetic studies to obtain quantitative characteristics of UV-driven isomerization were first performed. The results obtained indicate dramatic differences in two subclasses, which should be considered when developing biologically active molecules.

Evolution of Chernobyl Corium in Water: Formation of Secondary Uranyl Phases.

Two crystalline phases, which are analogues of common secondary uranyl minerals, namely, becquerelite (Ca[(UO2)6O4 (OH)6]·8H2O) and phurcalite (Ca2[(UO2)3O2 (PO4)2]·7H2O) were identified on the surface of a Chernobyl corium-containing sample affected by hydrothermal alteration in distilled water at 150 °C for one year. Phases were characterized using Single-Crystal X-ray Diffraction Analysis (SCXRD) as well as optical and scanning electron microscopy. Features of the structural architecture of novel phases, which come from the specific chemical composition of the initial fragment of Chernobyl sample, are reported and discussed. Precise identification of these phases is important for modelling of severe nuclear accidents and their long-term consequences, including expected corium-water interaction processes at three damaged Units of the Nuclear Power Plant Fukushima Daiichi.

Crystal Chemistry of the Copper Oxalate Biomineral Moolooite: The First Single-Crystal X-ray Diffraction Studies and Thermal Behavior.

Moolooite, Cu(C2O4)·nH2O, is a typical biomineral which forms due to Cu-bearing minerals coming into contact with oxalic acid sources such as bird guano deposits or lichens, and no single crystals of moolooite of either natural or synthetic origin have been found yet. This paper reports, for the first time, on the preparation of single crystals of a synthetic analog of the copper-oxalate biomineral moolooite, and on the refinement of its crystal structure from the single-crystal X-ray diffraction (SCXRD) data. Along with the structural model, the SCXRD experiment showed the significant contribution of diffuse scattering to the overall diffraction data, which comes from the nanostructural disorder caused by stacking faults of Cu oxalate chains as they lengthen. This type of disorder should result in the chains breaking, at which point the H2O molecules may be arranged. The amount of water in the studied samples did not exceed 0.15 H2O molecules per formula unit. Apparently, the mechanism of incorporation of H2O molecules governs the absence of good-quality single crystals in nature and a lack of them in synthetic experiments: the more H2O content in the structure, the stronger the disorder will be. A description of the crystal structure indicates that the ideal structure of the Cu oxalate biomineral moolooite should not contain H2O molecules and should be described by the Cu(C2O4) formula. However, it was shown that natural and synthetic moolooite crystals contain a significant portion of "structural" water, which cannot be ignored. Considering the substantially variable amount of water, which can be incorporated into the crystal structure, the formula Cu(C2O4)·nH2O for moolooite is justified.

One of Nature's Puzzles Is Assembled: Analog of the Earth's Most Complex Mineral, Ewingite, Synthesized in a Laboratory.

Through the combination of low-temperature hydrothermal synthesis and room-temperature evaporation, a synthetic phase similar in composition and crystal structure to the Earth's most complex mineral, ewingite, was obtained. The crystal structures of both natural and synthetic compounds are based on supertetrahedral uranyl-carbonate nanoclusters that are arranged according to the cubic body-centered lattice principle. The structure and composition of the uranyl carbonate nanocluster were refined using the data on synthetic material. Although the stability of natural ewingite is higher (according to visual observation and experimental studies), the synthetic phase can be regarded as a primary and/or metastable reaction product which further re-crystallizes into a more stable form under environmental conditions.

The Tail Wags the Dog: The Far Periphery of the Coordination Environment Manipulates the Photophysical Properties of Heteroleptic Cu(I) Complexes.

In this work we show, using the example of a series of [Cu(Xantphos)(N^N)]+ complexes (N^N being substituted 5-phenyl-bipyridine) with different peripheral N^N ligands, that substituents distant from the main action zone can have a significant effect on the physicochemical properties of the system. By using the C≡C bond on the periphery of the coordination environment, three hybrid molecular systems with -Si(CH3)3, -Au(PR3), and -C2HN3(CH2)C10H7 fragments were produced. The Cu(I) complexes thus obtained demonstrate complicated emission behaviour, which was investigated by spectroscopic, electrochemical, and computational methods in order to understand the mechanism of energy transfer. It was found that the -Si(CH3)3 fragment connected to the peripheral C≡C bond changes luminescence to long-lived intra-ligand phosphorescence, in contrast to MLCT phosphorescence or TADF. The obtained results can be used for the design of new materials based on Cu(I) complexes with controlled optoelectronic properties on the molecular level, as well as for the production of hybrid systems.

Targeted Synthesis of NIR Luminescent Rhenium Diimine cis,trans-[Re( NN )(CO)2 (L)2 ]n+ Complexes Containing N-Donor Axial Ligands: Photophysical, Electrochemical, and Theoretical Studies.

The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re( NN )(CO)3 (NCMe)]OTf ( NN =phenantroline and neocuproine) afforded cis,trans-Re( NN )(CO)2 (NCMe)2 ]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4'-bipyridine, N-methyl-4,4'-bipyridine) gave a novel family of the diimine cis,trans-[Re( NN )(CO)2 (L)2 ]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from 711 to 805 nm. The nature of emissive excited states was studied using DFT calculations to show dominant contribution of 3 MLCT (dπ(Re)→π*( NN )) character. Electrochemical (CV and DPV) studies of the monocationic diimine complexes revealed one reduction and one oxidation wave assigned to reduction of the diimine moiety and oxidation of the rhenium center, respectively.

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines.

A series of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines was synthesized for the first time by the reactions of chloroethynylphosphonates with unsubstituted and 5(6)-substituted 2-thiouracils. The reaction of chloroethynylphosphonates with 6-substituted 2-thiouracils bearing electron-donor groups (CH3, Ph) proceeded with high regioselectivity involving the cyclization through the N3-nitrogen atom to form new 3-phosphonylated thiazolo[3,2-a]-5-oxopyrimidines with good yield. In the case of unsubstituted and 5-methyl-2-thiouracils, cyclization occurred predominantly through the N1 atom and partially via the N3-nitrogen atom to form a mixture of the corresponding thiazolo[3,2-a]-7- and 5-oxopyrimidines. A dramatic change in the reaction regioselectivity was observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio.

Hydrolysis of Hexacarbonyltechnetium(I) Cation: Formation and Structure of Technetium Carbonyl Hydride 99Tc3H(CO)14.

Reaction of [99Tc(CO)6]ClO4 with alkali in aqueous solutions yields yellow 99Tc3H(CO)14 as the major product. On the other hand, [99TcH(CO)5] becomes the major product when the reaction with alkali is combined with the extraction into hexane. The molecular structure of 99Tc3H(CO)14, determined by SCXRD, is composed of the 99Tc2(CO)9 fragment bound to the 99Tc(CO)5 fragment via the hydrogen bridge and weak metal-metal bond. This compound crystallizes in the monoclinic system, space group P21/n, a = 9.6954(2) Å, b = 15.0985(3) Å, c = 14.5090(3) Å, and ß = 104.925(2)°. 99Tc3H(CO)14 was additionally characterized by IR spectroscopy. The mechanism of hydrolysis of [99Tc(CO)6]ClO4 was suggested.

Luminescent organic dyes containing a phenanthro[9,10-D]imidazole core and [Ir(N

A family of diimine (N^N) and cyclometalating (N^C) ligands based on a phenanthro-imidazole aromatic system: 2-pyridyl-1H-phenanthro[9,10-d]imidazole (N^N); 2-R-1-phenyl-1H-phenanthro[9,10-d]imidazole, R = phenyl (N^C4), 3-iodophenyl (N^C5) and 4-nitrophenyl (N^C6) were prepared. It was found that N^C4 and N^C5 show π-π* fluorescence typical of aromatic systems of this sort, whereas the donor-acceptor architecture of N^C6 leads to strong emission solvatochromism and acidochromism, indicating the charge transfer character of the fluorescence observed. Six iridium(iii) complexes (1-6) [Ir(N^C#)2(N^N)]+, where # = 1-6 and N^C1 = 2-phenylpyridine, N^C2 = 2-(benzo[b]thiophen-2-yl)pyridine, and N^C3 = methyl 2-phenylquinoline-4-carboxylate, were also synthesized and characterized. The complexes obtained display moderate to bright phosphorescence with quantum yields up to 46% in degassed solution. The photophysical characteristics of 1-6 were studied in detail. DFT and TD DFT calculations were used for the assignment of electronic transitions responsible for the absorption and emission of these compounds. The variations in the cyclometalating ligand structure give rise to rich photophysics of the complexes obtained. It was found that the orbitals of both N^C and N^N ligands make a major contribution to the formation of emissive excited states and a delicate balance between the energy of the ligands' frontier orbitals determines the emission character.

Five- and Six-Coordinated Silver(I) Complexes Formed by a Metallomacrocyclic Ligand with a "Au2N2" Donor Group: Observation of Pendulum and Linear Motions and Dual Phosphorescence.

The six-coordinated silver(I) complex [Au2Ag(µ-(PPh2)2py)2(OTf)2](OTf), 4 (py = pyridine, OTf = CF3SO3), and the five-coordinated silver(I) complex [Au2Ag(acetone)(µ-(PPh2)2py)2](PF6)3, 6, were prepared by the reaction of the precursor complexes 1(OTf)2 and 1(PF6)2, in which 1 = [Au2(µ-(PPh2)2py)2]2+, with 1 equiv of Ag(OTf) in dichloromethane and excess of Ag(PF6) in a mixture of dichloromethane/acetone, respectively. Also, the five-coordinated silver(I) complex [Au2Ag(µ-(PPh2)2py)2(py)(OTf)](OTf)2, 5, was obtained by the reaction of 4 with pyridine. The clusters 4-6 were characterized using multinuclear NMR spectroscopy and elemental microanalysis. The single-crystal X-ray diffraction analysis revealed the octahedral and distorted square pyramidal geometries around the silver(I) centers in the crystal structures of 4 and 6, respectively; a dynamic structure was observed for cluster 5 due to pendulum motion of the Ag(pyridine) moiety, which was anchored in the metallomacrocyclic unit [Au2(µ-(PPh2)2py)2]2+. Although the crystal structure of 6 did not display disorders for the silver atom and the acetone ligand similar to that observed for 5, the low-temperature NMR spectroscopies and calculations show a dynamic structure for cluster 6 due to linear motion of the Ag(acetone) moiety. The reaction of the precursor complex 1(PO2F2)2 with 2 equiv of Ag(PO2F2) yielded the tetranuclear Au2Ag2 cluster [Au2Ag2(PO2F2)2(µ-(PPh2)2py)2](PO2F2)2, 7, with a planar-shaped {Au2Ag2} metal core in which alternating Au and Ag atoms occupy the tetragon vertices and showed a strong argentophillic interaction between the silver(I) centers. All clusters 4-7 are emissive in the solid state, and the origins of their emissive excited states were determined using time-dependent density functional theory calculations. Cluster 7 showed a dual phosphorescence emission, which displays strong dependence of the contributions of each emissive component onto the excitation wavelength.

Binuclear Gold(I) Phosphine Alkynyl Complexes Templated on a Flexible Cyclic Phosphine Ligand: Synthesis and Some Features of Solid-State Luminescence.

A flexible bidentate cyclic phosphine, namely, 1,5-bis(p-tolyl)-3,7-bis(pyridin-2-yl)-1,5-diaza-3,7-diphosphacyclooctane (PNNP), was used as a template to construct a family of binuclear heteroleptic phosphine alkynyl complexes [PNNP(AuC2R)2], with R = Ph, C6H10OH, C5H8OH, (CH3)2COH, Ph2COH. All complexes obtained were characterized by CHN elemental analysis, NMR spectroscopy, and single-crystal X-ray analysis. It was found that the gold(I) complexes demonstrate a different organization of the crystal structure depending on the nature of the cocrystallized solvent (dichloromethane, acetone, and acetonitrile) because of formation of the supramolecular complexes through hydrogen bonding. These weak interactions appear to determine the conformation, packing, and spatial cooperation of flexible complex molecules that are reflected in the photophysical properties, which were carefully investigated in solution and in the solid state. The complexes demonstrate weak emission in solution at room temperature, and freezing results in blue shifting of the emission, which is accompanied by a significant increase in the luminescence intensity. Being isolated from dichloromethane, all gold(I) complexes exhibit green phosphorescence in the solid state, and the complexes with R = Ph and Ph2COH display substantial variation of their emission color after recrystallization from acetone and acetonitrile, respectively, which manifests itself as a significant bathochromic shift of up to 120 nm. The structural nonrigidity of the gold(I) complexes obtained and its impact on the properties of low-energy excited states were investigated in detail by density functional theory calculations, which indicate the significant role of the structural flexibility of the PNNP ligand in the formation of the low-energy excited states and confirm the impact of rotation of the functional groups in the coordination sphere on the emission properties of complexes.

Chemically Induced Polytypic Phase Transitions in the Mg[(UO2)(TO4)2(H2O)](H2O)4 (T = S, Se) System.

Chemically induced polytypic phase transitions have been observed during experimental investigations of crystallization in the mixed uranyl sulfate-selenate Mg[(UO2)(TO4)2(H2O)](H2O)4 (T = S, Se) system. Three different structure types form in the system, depending upon the Se:S ratio in the initial aqueous solution. The phases with the Se/(Se + S) ratios (in mol %) in the ranges 0-9, 16-47, and 58-100 crystallize in the space groups P21, Pmn21, and P21/c, respectively. The structures of the phases are based upon the same type of uranyl-based sulfate/selenate chains that, through hydrogen bonds, are linked into pseudolayers of the same topological type. The layers are linked into three-dimensional structures via interlayer Mg-centered octahedra. The three structure types contain the same layers but with different stacking sequences that can be conveniently described as belonging to the 1M, 2O, and 2M polytypic modifications. The Se-for-S substitution demonstrates a strong selectivity with preferential incorporation of Se into less tightly bonded T1 site. The larger ionic radius of Se6+ relative to S6+ induces rotation of (T1O4) tetrahedra in the adjacent layers and reconstruction of the structure types. From the information-theoretic viewpoint, the intermediate Pmn21 structure type is more complex than the monoclinic end-member structure types.

Allabogdanite, the high-pressure polymorph of (Fe,Ni)2P, a stishovite-grade indicator of impact processes in the Fe-Ni-P system.

Allabogdanite, (Fe,Ni)2P, is the only known natural high-pressure phase reported in the Fe-Ni-P system. The mineral, which was previously described from a single meteorite, the Onello iron, is now discovered in the Santa Catharina and Barbianello nickel-rich ataxites. The occurrence of allabogdanite in Santa Catharina, one of the largest and well-studied meteorites, suggests that this mineral is more common than was believed. The formation of allabogdanite-bearing phosphide assemblages in a given meteorite provides evidence that it experienced peak pressure of at least 8 GPa at a temperature above 800 °C. Since the pressure-temperature stability parameters of allabogdanite fall within the margins of the stishovite (rutile-type SiO2) stability area, the former can be employed as a convenient stishovite-grade indicator of significant impact events experienced by iron and stony-iron meteorites and their parent bodies.

Structural complexity of natural uranyl sulfates.

Uranyl sulfates, including those occurring in Nature (∼40 known members), possess particularly interesting structures. They exhibit a great dimensional and topological diversity of structures: from those based upon clusters of polyhedra to layered structures. There is also a great variability in the type of linkages between U and S polyhedra. From the point of view of complexity of those structures (measured as the amount of Shannon information per unit cell), most of the natural uranyl sulfates are intermediate (300-500 bits per cell) to complex (500-1000 bits per cell) with some exceptions, which can be considered as very complex structures (>1000 bits per cell). These exceptions are minerals alwilkinsite-(Y) (1685.95 bits per cell), sejkoraite-(Y) (1859.72 bits per cell), and natrozippeite (2528.63 bits per cell). The complexity of these structures is due to an extensive hydrogen bonding network which is crucial for the stability of these mineral structures. The hydrogen bonds help to propagate the charge from the highly charged interlayer cations (such as Y3+) or to link a high number of interlayer sites (i.e. five independent Na sites in the monoclinic natrozippeite) occupied by monovalent cations (Na+). The concept of informational ladder diagrams was applied to the structures of uranyl sulfates in order to quantify the particular contributions to the overall informational complexity and identifying the most contributing sources (topology, real symmetry, interlayer bonding).

Reactions of Cyclometalated Platinum(II) [Pt(N∧C)(PR3)Cl] Complexes with Imidazole and Imidazole-Containing Biomolecules: Fine-Tuning of Reactivity and Photophysical Properties via Ligand Design.

This work describes interaction of a family of [Pt(N∧C)(PR3)Cl] complexes with imidazole (Im), possible application of this chemistry for regioselective labeling of proteins through imidazole rings of histidine residues and employment of the resulting phosphorescent products in bioimaging. It was found that the complexes containing aliphatic phosphines display reversible substitution of chloride ligand for imidazole function that required considerable excess of imidazole to obtain full conversion into the substituted [Pt(ppy)(PR3)(Im)] product, whereas the substitution in the complexes with aromatic phosphines readily proceeds in 1:1.5 mixture of reagents. Rapid, selective, and quantitative coordination of imidazole to the platinum complexes enabled regioselective labeling of ubiquitin. X-ray protein crystallography of the {[Pt(ppy)(PPh3)]/ubiquitin} conjugate revealed direct bonding of the platinum center to unique histidine-68 residue through the nitrogen atom of imidazole function, the coordination being also supported by noncovalent interaction of the ligands with the protein secondary structure. The variations of the cyclometalating N∧C ligands gave a series of [Pt(N∧C)(PPh3)Cl] complexes (N∧C = 2-phenylpyridine, 2-(benzofuran-3-yl)pyridine, 2-(benzo[b]thiophen-3-yl)pyridine, methyl-2-phenylquinoline-4-carboxylate), which were used to investigate the impact of N∧C-ligand onto photophysical properties of the imidazole complexes and conjugates with human serum albumin (HSA). The chloride ligand substitution for imidazole and formation of the conjugates results in ignition of the platinum chromophore luminescence with substantially higher quantum yield in the latter case. Variation of the metalating N∧C-ligand made possible the shift of the emission to the red region of visible spectrum for both types of the products. Cell-viability tests revealed low cytotoxicity of all {[Pt(N∧C)(PPh3)Cl]/HSA} conjugates, while PLIM experiments demonstrated their high potential for oxygen sensing.

Heterometallic Cluster-Capped Tetrahedral Assemblies with Postsynthetic Modification of the Metal Cores.

Combining the star-shaped alkynyl ligands with low-nuclearity gold-copper triphosphane clusters produces 3D metallocage aggregates, which demonstrate room temperature phosphorescence in solution (max Φem =0.6). Their luminescence mainly originates from cluster-localized metal-to-ligand charge transfer excited state. These supramolecular assemblies can be easily converted into the isostructural gold-silver congeners by the direct exchange of the metal ions. Such modification of the terminal metal cores switches the emission to the intraligand (alkyne) electronic transitions of the triplet manifold, that represents an unusual optical functionality among the metallocycle/metallocage complexes.

ℇ-RbCuCl3, a new polymorph of rubidium copper trichloride: synthesis, structure and structural complexity.

A novel polymorph of RbCuCl3 (rubidium copper trichloride), denoted ℇ-RbCuCl3, has been prepared by chemical vapour transport (CVT) from a mixture of CuO, CuCl2, SeO2 and RbCl. The new polymorph crystallizes in the orthorhombic space group C2221. The crystal structure is based on an octahedral framework of the 4H perovskite type. The Rb+ and Cl- ions form a four-layer closest-packing array with an ABCB sequence. The Cu2+ cations reside in octahedral cavities with a typical [4 + 2]-Jahn-Teller-distorted coordination, forming four short and two long Cu-Cl bonds. ℇ-RbCuCl3 is the most structurally complex and most dense among all currently known RbCuCl3 polymorphs, which allows us to suggest that it is a high-pressure phase, which is unstable under ambient conditions.