Lanthanide/ATP interaction in water mediated by luminescent hemispherical-shaped complexes

Ligand LH(2), composed of two bipyridylcarboxylate fragments linked to an amino butyl chain, reacts with europium and terbium to form luminescent complexes in water at neutral pH. When testing these unsaturated complexes as anion sensors with NO(3)(-), HPO(4)(2)(-), AMP, ADP, and ATP, a marked selectivity is observed for HPO(4)(2)(-) and ATP(4)(-) at pH = 7.0. The interaction of these anions with the complex was investigated by means of absorption and emission spectroscopies. With ATP(4)(-), ES-MS and (31)P NMR experiments revealed the formation of a [Ln.L.(ATP)](3)(-) ternary species.     

Hydrothermal Synthesis, Structure, and Solid State (19)F NMR Study of ULM-17: (H(3)O)(2)[V(4)(HPO(4))(PO(4))(3)O(6)F](2)[NC(7)H(14)](6)

(H(3)O)(2)[V(4)(HPO(4))(PO(4))(3)O(6)F](2)[NC(7)H(14)](6) (labeled ULM-17) has been hydrothermally synthesized (150 degrees, 24 h, autogeneous pressure). It is monoclinic (space group P2(1)/c (No. 14)) with a = 21.4747(6) ?, b = 17.7223(5) ?, c = 20.1616(6) ?, beta = 94.329(1) degrees, and Z = 4. The structure consists in the hexagonal close packing of discrete hydronium cations, protonated quinuclidine and molecular anions [V(4)(HPO(4))(PO(4))(3)O(6)F](4)(-) (1) The structure presents two kinds of octameric anions built up from the tetrahedral arrangement of V(V)O(5)F octahedra sharing edges and vertices, capped by phosphorus tetrahedra. The stability of the solid is ensured via strong hydrogen bonds between the oxygens of the polyanions and the hydrogens of both hydronium and quinuclidinium cations. The particuliar location of fluorine at the center of the molecular anion 4-fold coordinated by V(V) was studied by solid state NMR.     

Selective anion sensing by a ruthenium(II)-bipyridyl-functionalized tripodal tris(urea) receptor

A tripodal tris(urea) ligand with 2,2'-bipyridyl (bpy) substituents (L) has been designed and synthesized, which coordinates with three equivalents of Ru(bpy)(2)Cl(2)·2H(2)O, followed by treatment with NH(4)PF(6), to afford the anion receptor [(bpy)(6)Ru(3)L](PF(6))(6) (1). The anion-binding behavior of the ligand L and the Ru(II)-bpy functionalized receptor 1 toward different anions was investigated by (1)H NMR (for L and 1), fluorescence, and UV-vis spectroscopy (for 1). Both compounds showed selective recognition of SO(4)(2-) or H(2)PO(4)(-) ions in the 1:1 binding mode in the NMR studies. The Ru(II) complex 1 displayed the metal-to-ligand charge transfer emission at 600 nm, which was quenched on addition of the sulfate and dihydrogen phosphate ions. Quantitative fluorescence titration experiments were carried out and the stability constants (log K) of the complex 1 with SO(4)(2-) and H(2)PO(4)(-) ions were obtained to be 4.73 and 4.69 M(-1) (1:1 binding mode), respectively.     

Binding of inorganic oxoanions to macrocyclic ligands: effect of the degree of protonation on supramolecular assemblies formed by phosphate and [18]aneN(6)

Five macrocycle-oxoanion adducts have been isolated from aqueous solutions containing 1,4,7,10,13,16-hexaazacyclooctadecane ([18]aneN(6), L) and phosphoric acid whose pH had been adjusted to selected values in the 1-8 range. Four products, (H(6)L)(H(2)PO(4))(6).2H(3)PO(4) (1), (H(6)L)(H(2)PO(4))(6) (2), (H(4)L)(H(2)PO(4))(4).2H(2)O (4), and (H(4)L)(HPO(4))(2).7H(2)O (5) crystallized from aqueous solutions at pH 1, 3, 6, and 8, respectively, while (H(4)L)(H(2)PO(4))(4) (3) crystallized on diffusion of EtOH into an aqueous reaction mixture at pH 6. Single-crystal X-ray structure determinations enabled an examination of supramolecular interactions between protonated forms of [18]aneN(6), phosphoric acid and its conjugate bases, and water of solvation. The macrocycle adopts a variety of conformations in order to accommodate the supramolecular constructs formed by the oxoanions and solvent molecules as the relative proportions of interacting species are altered. At pH 1 and 3, the fully protonated macrocycle, [LH(6)](6+), is found with six H(2)PO(4)(-) anions. At pH 6 and 8, the tetraprotonated macrocycle, [LH(4)](4+), crystallizes with four H(2)PO(4)(-) and two HPO(4)(2)(-), respectively. Variations in the solute of crystallization are evident, with phosphoric acid being present at the lowest pH and water at pH 6 and 8. In 5, the seven unique water molecules form a string-of-pearls motif within which a new heptameric isomer, consisting of a water pentamer that uses a single water to interact with the other two unique water molecules, is found. Structures 1, 2, 4, and 5 exhibit eta-3 H-bonding of ammonium protons to a single oxygen of the guest phosphates located above and below the macrocyclic ring. In 3, two phosphate oxygens of the cavity anion interact with the macrocycle, one of which participates in eta-2 H-bonding with ammonium groups.     

From the tetra(amino) phosphonium cation, [P(NHPh)4]+, to the tetra(imino) phosphate trianion, [P(NPh)4]3-, two-faced ligands that bind anions and cations

The tetraanilino phosphonium cation, [P(N(H)Ph)4]+, 1+, is sequentially deprotonated by Bu(n)Li in thf. The deprotonation reaction of the chloride derivative, Cl, was monitored by (31)P NMR, which revealed the successive formation of the neutral [P(N(H)Ph)3(NPh)], 2, the monoanionic [P(N(H)Ph)2(NPh)2]-, 3-, the dianionic [P(N(H)Ph)(NPh)3]2-, 4(2-), and finally the trianionic species [P(NPh)(4)](3-), (3-). Considering the isoelectronic relationship of oxo, =O, and imino groups, =NR, as well as hydroxy, -OH, and amino groups, -N(H)R, the neutral complex corresponds to phosphoric acid, H3PO4, whereas the anions 3-, 4(2-) and 5(3-) are analogues of dihydrogen phosphate, H2PO4-, monohydrogenphosphate, HPO4(2-), and orthophosphate ions, PO4(3-), respectively. Solid state structures were obtained of 1Cl, 2LiCl(thf)(2), 3Li(thf)(3.5), 3Li(2)Cl(thf)(4.25), 3Li(2)Cl(thf)(6) and 5Li(4)Cl(thf)(4). All systems provide two separate N-P-N chelation sites at opposite ligand faces, either consisting of the di(amino) arrangement P(NH)(2), acting as a double H-bond donor, the di(imino) arrangement PN(2), donating two electron pairs, or the mixed amino imino arrangement P(N)(NH), which supplies both electron pair and H-donor site. Interesting in this aspect is the mixed amino imino derivative 3- which has the ability to chelate a Lewis acid, such as a metal ion, at one face and a Lewis base, such as an anionic or neutral donor at the opposite ligand face. The formation of 1-D aggregates and the entrapment of lithium chloride are key characteristics of the supramolecular structures of the discussed complexes.     

Selective recognition of monohydrogen phosphate by fluorescence enhancement of a new cerium complex

Bis(8-hydroxy quinoline-5-solphonate) cerium(III) chloride (Ce(QS)(2)Cl) (L) was synthesized and then used as a novel fluorescent sensor for anion recognition. Preliminarily study showed that fluorescence of L enhanced selectively in the presence of HPO(4)(2-) ion. This enhancement is attributed to a 1:1 complex formation between L and HPO(4)(2-) anion. The association constant of 1:1 complex of L-HPO(4)(2-) was calculated as 3.0×10(6). Thus, L was utilized as a basis for a selective detection of HPO(4)(2-) anion in solution. The linear response range of the proposed fluorescent chemo-sensor covers a concentration range of HPO(4)(2-) from 3.3×10(-7) to 5.0×10(-6) mol L(-1) with a detection limit of 2.5×10(-8) mol L(-1). L showed selective and sensitive fluorescence enhancement response toward HPO(4)(2-) ion in comparison with I(3)(-), NO(3)(-), CN(-), CO(3)(2-), Br(-), Cl(-), F(-), H(2)PO(4)(-) and SO(4)(2-) ions. It was probably attributed to the higher stability of the inorganic complex between HPO(4)(2-) ion and L. The method was successfully applied for analysis of phosphate ions in some fertilizers samples.     

Synthesis and anion sensing of water-soluble metallomacrocycles

The self-assembly of (TMEDA)Pd(NO(3))(2) or (TMEDA)Pt(NO(3))(2) (where TMEDA = N(1),N(1),N(2),N(2)-tetramethylethane-1,2-diamine) and anthracene- or ferrocene-based diimidazole ligands (L(1-3)) in aqueous solution affords a series of positively charged [M(2)L(2)](4+) dimetallomacrocycles. Their structures were characterized by (1)H NMR and electrospray ionization mass spectrometry and in the cases of {[(TMEDA)Pd](2)L(1)(2)}(NO(3))(4) (1), {[(TMEDA)Pd](2)L(1)(2)}(PF(6))(4) (1a), and {[(TMEDA)Pd](2)L(3)(2)}(NO(3))(4) (4) by single-crystal X-ray diffraction analysis. Interestingly, the NMR spectra of 1 and 1a revealed that the difference of their structures, as confirmed by X-ray diffraction analysis, was that a NO(3)(-) of 1 was encapsulated inside the cavity of the basket-shaped metallomacrocycle by C-H···O hydrogen bonds, while PF(6)(-) of 1a was bound outside by C-H···F hydrogen bonds. The fluorescence titration experiment exhibited the formation of 1:1 host-guest complexation for anthracene-based positively charged [M(2)L(2)](4+)-type metallomacrocycles with NO(3)(-). The interactions between metallomacrocycles and various anions were investigated via fluorescence titration and cyclic voltammetry studies, respectively.     

Oxyanion-encapsulated caged supramolecular frameworks of a tris(urea) receptor: evidence of hydroxide- and fluoride-ion-induced fixation of atmospheric CO2 as a trapped CO3(2-) anion

A tris(2-aminoethyl)amine-based tris(urea) receptor, L, with electron-withdrawing m-nitrophenyl terminals has been established as a potential system that can efficiently capture and fix atmospheric CO(2) as air-stable crystals of a CO(3)(2-)-encapsulated molecular capsule (complex 1), triggered by the presence of n-tetrabutylammonium hydroxide/fluoride in a dimethyl sulfoxide solution of L. Additionally, L in the presence of excess HSO(4)(-) has been found to encapsulate a divalent sulfate anion (SO(4)(2-)) within a dimeric capsular assembly of the receptor (complex 2) via hydrogen-bonding-activated proton transfer between the free and bound HSO(4)(-) anions. Crystallographic results show proof of oxyanion encapsulation within the centrosymmetric cage of L via multiple N-H···O hydrogen bonds to the six urea functions of two inversion-symmetric molecules. The solution-state binding and encapsulation of oxyanions by N-H···O hydrogen bonding has also been confirmed by quantitative (1)H NMR titration experiments, 2D NOESY NMR experiments, and Fourier transform IR analyses of the isolated crystals of the complexes that show huge spectral changes relative to the free receptor.     

Ratiometric fluorescent receptors for both Zn2+ and H2PO4(-) ions based on a pyrenyl-linked triazole-modified homooxacalix[3]arene: a potential molecular traffic signal with an R-S latch logic circuit

A ratiometric fluorescent receptor with a C(3) symmetric structure based on a pyrene-linked triazole-modified homooxacalix[3]arene (L) was synthesized and characterized. This system exhibited an interesting ratiometric detection signal output for targeting cations and anions through switching the excimer emission of pyrene from the "on-off" to the "off-on" type in neutral solution. (1)H NMR titration results suggested that the Zn(2+) center of receptor L·Zn(2+) provided an excellent pathway of organizing anion binding groups for optimal host-guest interactions. It is thus believed that this receptor has potential application in sensing, detection, and recognition of both Zn(2+) and H(2)PO(4)(-) ions with different optical signals. In addition, the fluorescence emission changes by the inputs of Zn(2+) and H(2)PO(4)(-) ions can be viewed as a combinational R-S latch logic circuit at the molecular level.     

Synthesis, crystal structure, and solid-state NMR spectroscopy of a new open-framework aluminophosphate (NH(4))(2)Al(4)(PO(4))(4)(HPO(4))xH(2)O

A new three-dimensional open-framework aluminophosphate (NH(4))(2)Al(4)(PO(4))(4)(HPO(4)).H(2)O (denoted AlPO-CJ19) with an Al/P ratio of 4/5 has been synthesized, using pyridine as the solvent and 2-aminopyridine as the structure-directing agent, under solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by solid-state NMR techniques. The alternation of the Al-centered polyhedra (including AlO(4), AlO(5), and AlO(6)) and the P-centered tetrahedra (including PO(4) and PO(3)OH) results in an interrupted open-framework structure with an eight-membered ring channel along the [100] direction. This is the first aluminophosphate containing three kinds of Al coordinations (AlO(4), AlO(5), and AlO(6)) with all oxygen vertexes connected to framework P atoms. (27)Al MAS NMR, (31)P MAS NMR, and (1)H --> (31)P CPMAS NMR characterizations show that the solid-state NMR techniques are an effective complement to XRD analysis for structure elucidation. Furthermore, all of the possible coordinations of Al and P in the aluminophosphates with an Al/P ratio of 4/5 are summarized. Crystal data: (NH(4))(2)Al(4)(PO(4))(4)(HPO(4))xH(2)O, monoclinic P2(1) (No. 4), a = 5.0568(3) A, b = 21.6211(18) A, c = 8.1724(4) A, beta = 91.361(4) degrees , V = 893.27(10) A(3), Z = 2, R(1) = 0.0456 (I > 2 sigma(I)), and wR(2) = 0.1051 (all data).     

(Thio)ureido anion receptors based on a 1,3-alternate oxacalix[2]arene[2]pyrimidine scaffold

In pursuit of highly preorganized macrocyclic host molecules for the complexation of anions, a series of oxacalix[2]arene[2]pyrimidine-based bis(thio)ureido receptors were synthesized and fully characterized. The pincer-like 1,3-alternate conformation of the oxacalix[4]arene scaffold, essential for an efficient host-guest interaction, was visualized by single-crystal X-ray analysis and supported by variable-temperature NMR studies. The anion binding properties of the receptors were evaluated via (1)H NMR titration experiments, showing intermolecular interactions with H(2)PO(4)(-), AcO(-), BzO(-), and Cl(-) ions. The host molecule bearing 4-nitrophenyl substituents on the bisurea binding pocket showed association constants in the range of 200-400 M(-1) in the strongly competitive solvent mixture of DMSO/0.5% H(2)O.     

Displacement method to develop highly sensitive and selective dual chemosensor towards sulfide anion

By utilizing a displacement method, a macrocyclic compound 1, could report the presence of sulfide anion, with the detection limit of 7.0 × 10(-7) mol/L; moreover, no interference was observed from other anions, including SO(3)(2-), HSO(3)(-), SO(4)(2-), ClO(4)(-), I(-), Br(-), Cl(-), F(-), IO(3)(-), HPO(4)(2-), PO(4)(3-), C(2)O(4)(2-), S(2)O(3)(2-), CO(3)(2-), AcO(-), CN(-) and P(2)O(7)(4-), making compound 1 a new, highly sensitive and selective sulfide anion chemosensor.     

Encapsulation of cyanometalates by a tris-macrocyclic ligand tricopper(II) complex: syntheses, structural variation, and magnetic exchange coupling pathways

The reaction of [M(CN)(6)](3-) (M = Cr(3+), Mn(3+), Fe(3+), Co(3+)) and [M(CN)(8)](4-/3-) (M = Mo(4+/5+), W(4+/5+)) with the trinuclear copper(II) complex of 1,3,5-triazine-2,4,6-triyltris[3-(1,3,5,8,12-pentaazacyclotetradecane)] ([Cu(3)(L)](6+)) leads to partially encapsulated cyanometalates. With hexacyanometalate(III) complexes, [Cu(3)(L)](6+) forms the isostructural host-guest complexes [[[Cu(3)(L)(OH(2))(2)][M(CN)(6)](2)][M(CN)(6)]][M(CN)(6)]30 H(2)O with one bridging, two partially encapsulated, and one isolated [M(CN)(6)](3-) unit. The octacyanometalates of Mo(4+/5+) and W(4+/5+) are encapsulated by two tris-macrocyclic host units. Due to the stability of the +IV oxidation state of Mo and W, only assemblies with [M(CN)(8)](4-) were obtained. The Mo(4+) and W(4+) complexes were crystallized in two different structural forms: [[Cu(3)(L)(OH(2))](2)[Mo(CN)(8)]](NO(3))(8)15 H(2)O with a structural motif that involves isolated spherical [[Cu(3)(L)(OH(2))](2)[M(CN)(8)]](8+) ions and a "string-of-pearls" type of structure [[[Cu(3)(L)](2)[M(CN)(8)]][M(CN)(8)]](NO(3))(4) 20 H(2)O, with [M(CN)(8)](4-) ions that bridge the encapsulated octacyanometalates in a two-dimensional network. The magnetic exchange coupling between the various paramagnetic centers is characterized by temperature-dependent magnetic susceptibility and field-dependent magnetization data. Exchange between the CuCu pairs in the [Cu(3)(L)](6+) "ligand" is weakly antiferromagnetic. Ferromagnetic interactions are observed in the cyanometalate assemblies with Cr(3+), exchange coupling of Mn(3+) and Fe(3+) is very small, and the octacoordinate Mo(4+) and W(4+) systems have a closed-shell ground state.     

Coordination networks with flexible ligands based on silver(I) salts: complexes of 1,3-bis(phenylthio)propane with silver(I) salts of PF6-, CF3COO-, CF3CF2COO-, CF3CF2)CF2COO-, p-TsO-, and CF3SO3-

The synthesis and characterization of nine coordination networks based on 1,3-bis(phenylthio)propane, L(3), and silver(I) salts of PF(6)(-) (1), CF(3)COO(-) (2), CF(3)CF(2)COO(-) (3), CF(3)CF(2)CF(2)COO(-) (4), p-TsO(-) (5, 6), and CF(3)SO(3)(-) (7-9) are reported. Only 1 and other "isostructural" complexes with weakly coordinating anions such as ClO(4)(-) and SbF(6)(-) are of the host-guest type. In all the other complexes, the anions and the acetone molecules, when present, are coordinated to the metal. Most of the complexes studied here form a 2D-coordination network. Only 4 and 5 adopt a polymer-like chain structure. The packing of the chains of 4 is pseudohexagonal compact, while that of 5 is of the centered type. In complex 1, the silver atom is tetrahedrally coordinated to the sulfur atoms of four different ligands. The PF(6)(-) anions and acetone molecules, sandwiched between silver-ligand cationic sheets, are held through van der Waals interactions. In each of the three perfluorocarboxylates (2-4), two silver atoms are joined by the anions in a diatomic bridging mode. The Ag...Ag distances are sufficiently short to indicate weak metal...metal interactions. The dimeric units in 2 and 3 are interconnected through the ligands, thereby generating a 2D-network of neutral sheets, while, in 4, the dimeric units are bound to four ligands and a 1D-coordination polymer is generated. In the case of the sulfonate anions (p-TsO(-) and CF(3)SO(3)(-)), the crystallization solvent influences the structure adopted. Thus, in 5, 7, and 9 obtained from petroleum ether, or other nonpolar solvents, two silver atoms are bound in a double-bridge fashion, while a monobridge mode is noted for 6 and 8, both recrystallized from diethyl ether. In 8, both bridging types are observed. The thermogravimetric investigation, in the room temperature-450 degrees C interval, of complexes 1, 3, and 7, which incorporate acetone molecules in their crystal structures, reveals a two-step weight loss for 1 (the acetone molecules are lost first followed by the ligands, leaving behind the silver salt), while complexes 3 and 7 decompose in a single step to metallic silver.     

Host-guest complexes [(H4L)(SiF6)2-4H2O] and [(H4L)(GeF6)2 4H2O] (L =meso-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)

Synthesis and X-ray structure analysis of host-guest complexes [(H₄L)(SiF₆)₂-4H₂O] (I) and [(H₄L)(GeF₆)₂-4H₂O] (II) are reported (L = meso-5,7,7,12,12,14-hexamethyl-l,4,8,11-tetraazacyclo-tetradecane). The crystals of both compounds are triclinic with close unit cell parameters. I: a = 9.576(3), b= 9.217(3), c= 8.334(2) å, α= 105.66(2), Ω= 83.68(2), α = 105.38(2)? II: a= 9.627(3), b = 9.358(3), c.= 8.497(4) A, a= 106.02(2), Ω = 83.74(2), α= 106.06(2)?. The structural units of the crystals are the (H₄L)⁴⁺ cations, the hexafluorosilicate (or hexafluowgemanate) anions, and the water molecules linked by a system of H bonds. The macrocycle in the complexes has C₁ symmetry. In the inorganic anions, the silicon as well as germanium atom is surrounded by an octahedron of six fluorine atoms.

     

Two-arm ferrocene amide compounds: synclinal conformations for selective sensing of dihydrogen phosphate ion

[structure: see text] Ferrocene compounds bearing multiple amido groups selectively bind with the H(2)PO(4)(-) ion over other anions. The one-arm receptors form 1:1 complexes with the H(2)PO(4)(-) ion, whereas the two-arm receptors can accommodate two H(2)PO(4)(-) ions. The complexation modes and binding strengths are deduced from the NMR, calorimetry, fluorescence, and cyclic voltammetry studies. The two-arm ferrocene hexamide receptors likely exist in synclinal conformations to incorporate tetrahydrofuran molecules and H(2)PO(4)(-) ions.     

Tri-, hepta- and octa-nuclear Ag(I) complexes derived from 2-pyridyl-functionalized tris(amido)phosphate ligand

Mild deprotonation of a 2-pyridyl (py)-functionalized phosphoric triamide [PO(NHpy)(3)] in the absence of an external base was studied in the presence of various silver(I) salts. Interesting examples of octa- and hepta-nuclear Ag(I) complexes coordinated to imido and pyridyl groups were obtained when more reactive Ag(I) salts, such as AgClO(4) and AgBF(4), were used, while the less reactive AgNO(3) reacts only with the peripheral pyridyl groups leading to a tri-nuclear cluster. Structural determination of these Ag(I) complexes show that sequential deprotonation of the ligand amino protons were achieved forming imido P(V) species analogous to the H(2)PO(4)(-) and HPO(4)(2-) ions.     

Lithiation of (tBuNH)3PNSiMe3 and formation of tetraimidophosphate complexes containing M3O3 rings (M = Li, K): X-ray structure of the stable radical [(Me3SiN)P(mu3-N(t)Bu)3[mu3-Li(THF)]3(OtBu))

The reaction of ((t)BuNH)(3)PNSiMe(3) (1) with 1 equiv of (n)BuLi results in the formation of Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] (2); treatment of 2 with a second equivalent of (n)BuLi produces the dilithium salt Li(2)[P(NH(t)Bu)(N(t)Bu)(2)(NSiMe(3))] (3). Similarly, the reaction of 1 and (n)BuLi in a 1:3 stoichiometry produces the trilithiated species Li(3)[P(N(t)Bu)(3)(NSiMe(3))] (4). These three complexes represent imido analogues of dihydrogen phosphate [H(2)PO(4)](-), hydrogen phosphate [HPO(4)](2)(-), and orthophosphate [PO(4)](3)(-), respectively. Reaction of 4 with alkali metal alkoxides MOR (M = Li, R = SiMe(3); M = K, R = (t)Bu) generates the imido-alkoxy complexes [Li(3)[P(N(t)Bu)(3)(NSiMe(3))](MOR)(3)] (8, M = Li; 9, M = K). These compounds were characterized by multinuclear ((1)H, (7)Li, (13)C, and (31)P) NMR spectroscopy and, in the cases of 2, 8, and 9.3THF, by X-ray crystallography. In the solid state, 2 exists as a dimer with Li-N contacts serving to link the two Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] units. The monomeric compounds 8 and 9.3THF consist of a rare M(3)O(3) ring coordinated to the (LiN)(3) unit of 4. The unexpected formation of the stable radical [(Me(3)SiN)P(mu(3)-N(t)Bu)(3)[mu(3)-Li(THF)](3)(O(t)Bu)] (10) is also reported. X-ray crystallography indicated that 10 has a distorted cubic structure consisting of the radical dianion [P(N(t)Bu)(3)(NSiMe(3))](.2)(-), two lithium cations, and a molecule of LiO(t)Bu in the solid state. In dilute THF solution, the cube is disrupted to give the radical monoanion [(Me(3)SiN)((t)BuN)P(mu-N(t)Bu)(2)Li(THF)(2)](.-), which was identified by EPR spectroscopy.     

Ionic liquid of choline chloride/malonic acid as a solvent in the synthesis of open-framework iron oxalatophosphates

Two new iron(III) oxalatophosphates, Cs2Fe(C2O4)(0.5)(HPO4)2 (1) and CsFe(C2O4)(0.5)(H2PO4)(HPO4) (2), have been synthesized by using a low melting point eutectic mixture of choline chloride and malonic acid as a solvent and characterized by single-crystal X-ray diffraction and magnetic susceptibility. Crystal data are as follows: compound 1, monoclinic, P2(1)/c (No. 14), a = 8.5085(4) A, b = 12.7251(6) A, c = 9.8961(4) A, beta = 107.117(1) degrees , V = 1024.01(8) A(3), Z = 4, and R(1) = 0.0264; compound 2, monoclinic, P2(1)/n (No. 14), a = 8.0038(3) A, b = 10.2923(3) A, c = 11.4755(4) A, beta = 100.507(1) degrees , V = 929.47(5) A(3), Z = 4, and R(1) = 0.0311. The structure of 1 comprises FeO6 octahedra connected by HPO4(2-) tetrahedra and bisbidentate oxalate anions to form a 3D framework containing intersecting 12-ring channels, with the charge-compensating Cs+ cations being located at the intersections of these channels. The structure of 2 consists of 2D layers of octahedral FeO6, tetrahedral H2PO4- and HPO4(2-) moieties, and bisbidentate oxalate ligands with the Cs+ cations between the layers. They are the first examples for the use of ionic liquid as a solvent in the synthesis of metal oxalatophosphates.     

Molecular properties of adsorbates that affect the growth kinetics of archerite (KDP)

We explore the molecular properties of adsorbates that dramatically affect growth kinetics and morphology of the [100] face of archerite, also known as potassium dihydrogen phosphate (KH(2)PO(4) or KDP). Aqueous complexes of Al(III), Fe(III), and Cr(III) are known to affect KDP growth, albeit the actual step-pinning complex(es) is unknown. Using in situ atomic force microscopy (AFM), we measured changes in the growth rates of the [100] face of KDP with supersaturation in the presence of trace amounts of [Co(NH(3))(6)](3+), [Fe(CN)(6)](3-), eta(1)-[Co(NH(3))(5)HPO(4)](+), eta(2)-[Co(NH(3))(4)HPO(4)](+), eta(2)-[Co(NH(3))(4)P(2)O(7)H(2)](+), and [Rh(H(2)PO(4))(2)(H(2)O)(4)](+). Unlike in experiments using trivalent-metals, these complexes do not change stoichiometry or structure on the timescale of step motion, so that the actual molecular interactions that affect growth can be studied. Step velocity and morphology on the [100] face are unaffected by outer-sphere coordination complexes of either charge. Surprisingly, inner-sphere phosphatoammine complexes do not affect growth rates regardless of how the phosphate group is coordinated to the metal. However, doping the growth solution with [Rh(H(2)PO(4))(2)(H(2)O)(4)](+) results in profound step pinning, matching the behavior of KDP surfaces grown in the presence of Rh(III) after an equilibration period. Not only is an inner-sphere phosphate group needed to dock a trivalent metal to the step edge, but compatible hydrogen bonding of the remainder of the inner-sphere ligands with the bulk lattice is also essential.