New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: syntheses, structures, and luminescent properties

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH(4))·[Ag(HL1)(NH(3))(H(2)O)] (1), {(NH(4))·[Ag(3)(HL1)(2)(NH(3))(H(2)O)]}(n) (2), [Ag(2)(HL1)(H(2)O)(2)](n) (3), [Ag(2)(HL2)(NH(3))(2)]·H(2)O (4), [Ag(H(2)L2)(H(2)O)](n) (5), [Ag(2)(HL2)](n) (6), [Ag(3)(L3)(NH(3))(3)](n) (7), [Ag(2)(HL3)](n) (8), and [Ag(6)(L3)(2)(H(2)O)(3)](n) (9) (H(3)L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H(3)L2 = 2-hydroxyl-4-carboxylbenzenesulfonic acid, H(3)L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction. Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH(3))(H(2)O)](-) anions and NH(4)(+) cations. Complex 2 exhibits 3-D host-guest framework which encapsulates ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from 1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)(2)(COO)(2)] binuclear units. Complex 4 exhibits 3-D hydrogen-bonding host-guest network which encapsulates water molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic linker bridged 1-D Ag-O-S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of complex 7 is formed by L3(-) trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O(4))(2)(Ag2O(5))(2)](∞) motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.     

Syntheses, structures and properties of silver-organic frameworks constructed with 1,2,3,4-benzenetetracarboxylic acid

The reactions of 1,2,3,4-benzenetetracarboxylic acid (H(4)mpda) and different silver(I) salts under hydrothermal or solvent evaporation conditions yielded four unusual coordination complexes with interesting frameworks: [Ag(4)(mpda)](n) (1), {[Ag(2.5)(mpda)(bpy)(2)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·(NO(3))(0.5)·(H(2)O)(9)}(n) (2), {[Ag(5)(mpda)(2)(bpy)(4)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·[Ag(bpy)(H(2)O)]·(H(2)O)(16)}(n) (3), {[Ag(2)(mpda)(H(2)O)]·[Ag(bpy)]·[Ag(bpy)]}(n) (4) (bpy = 4,4'-bipyridine). Complex 1 displays a novel (3,4,7)-connected {4.6(2)}{4.6(5)}{4(2).6(13).8(5).10} topology, in which the carboxylic groups of the mpda(4-) ligand adopt variable coordination modes. In 1, besides Ag-O coordination bonding, AgAg and Agaromatic intermolecular interactions also make their appearance. In complexes 2-4, rare architectures comprising three or four isolated coordination polymers within the same crystalline structure have been obtained, respectively. In 2 and 3, neighboring layers are linked together through water tapes into a three-dimensional supramolecular architecture, which is also consolidated by π···π stacking, while independent infinite rod-like polymer chains fill the void space between layers. Interestingly, an anionic (H(2)O-NO(3)(-))(n) layer, built from water tapes and nitrate anions as well as consolidated by the mpda(4-) ligands, has been structurally identified in compound 2. A new water tape constructed from alternating tetramers and decamers has been obtained in compound 3. In compound 4, a right-handed helical chain and two rod-like polymeric chains are interconnected through host-guest molecular recognition to generate a three-dimensional chiral supramolecular architecture. Bulk materials for 1 and 4 have second-harmonic generation activity, being approximately 0.6 and 0.4 times that of urea. The IR spectra, thermogravimetric analysis and luminescent properties of all compounds were also investigated.     

Self-assembly of silver(I) and gold(I) N-heterocyclic carbene complexes in solid state, mesophase, and solution

The assembly of silver(I) and gold(I) complexes of functionalized N-heterocyclic carbenes (NHCs) of the type [M(C(n),amide-imy)(2)][anion] were studied, in which C(n),amide-imy stands for an NHC of imidazol-2-ylidene having one N-alkyl substituent (C(n)H(2n+1)) and one N-acetamido substituent, while the anions are Br(-), NO(3)(-), BF(4)(-) or PF(6)(-). A single crystal X-ray diffraction study reveals that self-assembly of [Ag(C(10),amide-imy)(2)][PF(6)] through Coulombic, hydrogen bonding, and hydrophobic interactions gives a lamellar structure with tubular architecture around the metal ion head core. Self-assembly of these functionalized NHC complexes also leads to the formation of the first example of thermotropic liquid crystals of silver(I)-NHCs and gels of gold(I)-NHC. Results from an infrared spectroscopy study show that the degree of chain motion in the gel state is smaller than that in the mesophase, yet comparable to that in the solid state. In addition, the technique of nuclear magnetic resonance diffusion ordered spectroscopy was found for the first time to be a good tool to study the phase transition of gels. Xerogels of gold(I)-NHCs display fibers, oriental lantern-shaped bundles of belts and helical fibers when observed under scanning electron and transmission electron microscopes.     

Spiral, herringbone, and triple-decker silver(I) complexes of benzopyrene derivatives assembled through eta(2)-coordination

Three novel silver(I) complexes with benzopyrene derivatives were synthesized and characterized in this paper. Treatment of AgClO(4)*H(2)O with 7-methylbenzo[a]pyrene (L(1)) afforded [Ag(2)(L(1))(toluene)(0.5)(ClO(4))(2)](n)() (1) which exhibits a 2-D sheet structure with double-stranded helical motifs. Reaction of AgCF(3)SO(3) with dibenzo[b,def ]chrysene (L(2)) gave rise to an unprecedented cocrystallization structure, ([Ag(2)(L(2))(CF(3)SO(3))(2)][Ag(2)(toluene)(2)(CF(3)SO(3))(2)])(n)() (2), formed by a 2-D neutral lamellar polymer and a 1-D neutral rodlike one. The ligand benzo[e]pyrene (L(3)) coordinated to silver(I) ions generating a closed triple-decker tetranuclear complex [Ag(4)(L(3))(4)(p-xylene)(ClO(4))(4)] (3) which can be regarded as a stacking polymer owing to existing intermolecular pi-pi stack interactions. The structural diversity of the silver(I) coordination polymers with polycyclic aromatic hydrocarbons is not only related to the stacking patterns of free polycyclic aromatic hydrocarbons in the crystalline state, but also the geometric shapes of the molecules for these free ligands. In addition, the coordination of solvents to metal ions plays a crucial role in the formation of the unprecedented coordination polymeric architectures. The ESR spectroscopic results, conductivity, and synthesis properties are also discussed.     

Anion dependent structures of luminescent silver(i) complexes

The reaction of AgX, where X = trifluoroacetate (CF(3)CO(2)(-), tfa), nitrate (NO(3)(-)), trifluoromethanesulfonate (triflate, CF(3)SO(3)(-), OTf), hexafluorophosphate (PF(6)(-)), or perchlorate (ClO(4)(-)), with 2,2',3' '-tripyridylamine (tpa) yields five novel silver(I) complexes, which have been structurally characterized. The five complexes have the same 1:1 stoichiometry of Ag/tpa but exhibit different modes of coordination, depending upon the counterion present in the compound. Compound 1, [Ag(tpa)(tfa)](n)(), forms a 1D coordination polymer of [Ag(tpa)(tfa)](2) dimer units linked through bridging tfa counterions. Compound 2, [Ag(tpa)(CH(3)CN)(NO(3))](n), forms a zigzag chain 1D coordination polymer exclusively through Ag-N bonds. In compounds 1 and 2, each tpa ligand is bound to two Ag(I) ions via a 2-py and a 3-py group. Compound 3, [Ag(tpa)(OTf)](n), forms a ribbonlike 1D coordination polymer, in which each tpa ligand binds to three different silver centers via all three pyridyl groups, and the counterion remains coordinated to the Ag(I) center. Compounds 4, [Ag(tpa)(CH(3)CN)](n)(PF(6))(n), and 5, [Ag(tpa)(CH(3)CN)](n)() (ClO(4))(n), display ribbonlike structures resembling that of 3, except that the counterions are not coordinated. All complexes are luminescent in acetonitrile solution, with emission maxima in the near-UV region (lambda(max) = 366, 368, 367, 367, and 368 nm for 1-5, respectively). At 77 K, the emission maxima are red-shifted to lambda(max) = 452, 453, 450, 450, and 454 nm for 1-5, respectively.     

Ionic liquids of bis(alkylethylenediamine)silver(I) salts and the formation of silver(0) nanoparticles from the ionic liquid system

We have prepared novel ionic liquids of bis(N-2-ethylhexylethylenediamine)silver(I) nitrate ([Ag(eth-hex-en)(2)]NO(3) and bis(N-hexylethylenediamine)silver(I) hexafluorophosphate ([Ag(hex-en)(2)]PF(6)), which have transition points at -54 and -6 degrees C, respectively. Below these transition temperatures, both the silver complexes assume amorphous states, in which the extent of the vitrification is larger for the eth-hex-en complex than for the hex-en complex. The diffusion coefficients of both the complex cations, measured between 30 (or 35) and 70 degrees C, are largely dependent on temperature; the dependence is particularly large in the case of the eth-hex-en complex cation below 40 degrees C. Small-angle X-ray scattering studies showed that the bilayer structure of the metal complex is formed in the liquid state for both the silver complexes. A direct observation of the yellowish [Ag(eth-hex-en)(2)]NO(3) liquid by transmission electron microscopy (TEM) indicates the presence of nanostructures, as a microemulsion, of less than 5 nm. Such structures were not clearly observed in the [Ag(hex-en)(2)]PF(6) liquid. Although the [Ag(eth-hex-en)(2)]NO(3) liquid is sparingly soluble in bulk water, it readily incorporates a small amount of water up to [water]/[metal complex] = 7:1. Homogeneous and uniformly sized silver(0) nanoparticles in water were created by the reduction of the [Ag(eth-hex-en)(2)]NO(3) liquid with aqueous NaBH(4), whereas silver(0) nanoparticles were not formed from the [Ag(hex-en)(2)]PF(6) liquid in the same way.     

Syntheses, structures and antimicrobial activities of water-soluble silver(I)-oxygen bonding complexes with chiral and racemic camphanic acid (Hca) ligands

Water-soluble, relatively light-stable, chiral and achiral silver(I) complexes [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n)(R- and S-Hca =(1R,4S)- and (1S,4R)-4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylic acid, respectively) prepared from the reaction of Ag(2)O with chiral and racemic Hca in 1:2 and 1:4 molar ratios were characterized by elemental analysis, TG/DTA, FTIR, and solution ((1)H, (13)C and (109)Ag) and solid-state ((13)C) NMR spectroscopy. Crystallography revealed that unique 2(1) helical polymer and zigzag structures were formed on self-assembly of the dimeric units in the crystals of [[Ag(2)(S-ca)(2)]](n) and three [[Ag(2)(ca)(2)(Hca)(2)]](n). In the crystal of [[Ag(2)(S-ca)(2)]](n) two 2(1) helices and a loop were observed in the stair-like polymer structure, whereas zigzag and a loop were seen in the crystals of three [[Ag(2)(ca)(2)(Hca)(2)]](n). Carbon NMR spectra in the solid state and in D(2)O indicated that these polymeric structures were loosely bound and fast ligand-exchange reactions took place in aqueous solution. The complexes, [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n), showed a wide spectrum of effective antimicrobial activity as anticipated for weak silver(i)-O bonding complexes. Similar antimicrobial activity of [[Ag(2)(ca)(2)]](n) and [[Ag(2)(ca)(2)(Hca)(2)]](n) against selected microorganisms suggested that ligand exchangeability played an important role as well as the coordination geometry of the silver(i) ion.     

Syntheses and structures of photochromic silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene

Five novel silver(I) coordination polymers with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3- thienyl)ethene (cis-dbe) were synthesized and are characterized in this paper. Treatment of AgCF(3)SO(3) or AgCF(3)CO(2) with cis-dbe afforded [Ag(2)(cis-dbe)(CF(3)SO(3))(2)] (1) and [Ag(2)(cis-dbe)(CF(3)CO(2))(2)] (2), and both complexes exhibit a 1-D infinite chain structure with two cyano groups and two thienyl groups of the ligand bridging four metal ions. Reaction of AgC(n)()F(2)(n)(+1)CO(2) with cis-dbe gave rise to an unprecedented cocrystallization of a 2-D sheet structure, [Ag(2)(cis-dbe)(C(n)F(2)(n)(+1)CO(2))(2)], where n = 2 (3), 3 (4), and 4 (5). Upon irradiation with 450 nm light, these five silver(I) complexes turned orange or red from yellow, and the color reverted to yellow on exposure to 560 nm light, indicative of the reversible cyclization/ring-opening reaction occurring in the crystalline phase. Furthermore, different anions gave not only the different structural dimensions but also the different photoresponsive patterns. The correlation between the crystal structures and the photochromic reactivity is discussed.     

Synthesis,structure, luminescence and electrochemical and antioxidant properties of anion-controlled silver(I) complexes with 2,2′-(1,4-butanediyl)bis-1,3-benzoxazole

To explore the influence of various anions on the self-assembly and properties of silver complexes, reactions of anions of silver salts with 2,2′-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) afforded four complexes, formulated as [Ag₂(BBO)₂(p-toluenesulfonate)₂] ( 1 ), {[Ag(BBO)(picrate)]}_∞ ( 2 ), {[Ag(BBO)_1/2(o-coumarate)]·DMF}_∞ ( 3 ) and {[Ag₂(BBO)₃](PF₆)₂}_∞ ( 4 ). These complexes were characterized using elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The crystal analysis results show that under the influence of coordination modes and steric hindrance of anions, the complexes exhibited binuclear ( 1 ), one-dimensional polymeric ( 2 and 3 ) and two-dimensional polymeric ( 4 ) structures. Compared with the BBO ligand, only complex 1 has a new emission peak at 428 nm, which is attributed to ligand–metal charge transfer. The emission peaks of complexes 2 – 4 are similar to those of the BBO ligand, which can be due to π–π* and n–π* transitions. These results indicate that anions can modulate the structures and luminescent properties of silver complexes. Moreover, cyclic voltammograms of 1 – 4 indicated an irreversible Ag⁺/Ag couple with the order of reversibility being 2 > 1 > 4 > 3 . In vitro antioxidant experiments showed that complex 3 has significant antioxidant activity against superoxide and hydroxyl radicals.     

The solution stability of copper(I) and silver(I) complexes with N-heterocyclic carbenes

The tris-benzimidazolium cage LH(3)(3+), in MeCN solution, in the presence of OH(-), forms with Cu(I) and Ag(I) ions complexes of formula [M(I)(LH)](2+), in which each metal is linearly coordinated by two carbenes and one imidazolium N-H fragment remains intact. To achieve two-coordination, the two N-heterocyclic moieties of the cage make a saloon-door type motion, with a conformationally costless rotation of ca. 30° each. The two [M(I)(LH)](2+) complexes show high thermodynamic stability and are inert with respect to metal substitution, due to the mechanical constraints imposed by the ligating framework. Complexation with Cu(I) and Ag(I) with the reference unidentate carbene ligand Q, derived from the benzimidazolium precursor QH(+), was studied for comparison. Both metals in MeCN form 1:1 and 1:2 complexes with the carbene ligand Q according to two stepwise equilibria. Q complexes of both metals are labile with respect to metal substitution and those of Ag(I) are more stable than those of Cu(I). A significant cooperative effect has been observed with the formation of the [Ag(I)Q(2)](+) complex.     

Toluene-sandwiched trinuclear copper(I) and silver(I) triazolates and phosphine adducts of dinuclear copper(I) and silver(I) triazolates

Cu (I) and Ag (I) complexes of the fluorinated triazolate ligand [3,5-(C3F7)2Tz](-) have been synthesized using the corresponding metal(I) oxides and the triazole. They form pi-acid/base adducts with toluene, leading to [Tol][M3][Tol] ([Tol]=toluene; [M3]={[3,5-(C3F7)2Tz]Cu}3 or {[3,5-(C3F7)2Tz]Ag}3) type structures. Packing diagrams show the presence of extended chains of the type {[Tol][M3][Tol]}infinity, but the intertoluene ring distances are too long for significant pi-arene/pi-arene contacts. These copper and silver triazolates react with PPh3 (at a 1:1 metal ion/P molar ratio), leading to dinuclear {[3,5-(C3F7)2Tz]Cu(PPh3)}2 and {[3,5-(C3F7) 2Tz]Ag(PPh3)}2. They feature a six-membered Cu(mu-N-N) 2Cu or Ag(mu-N-N)2Ag core with a boat conformation.     

Single-strand helical complexes constructed from 2-pyridinyl-3-pyridinylmethanone: tuning the helical pitch length by variation of metal cation and/or counter anion

The new ligand 2-pyridinyl-3-pyridinylmethanone (L) proves to be an excellent building block for the construction of single-strand helical architectures. A series of helical complexes have been synthesized by the reaction of L with various metal salts, in which L exhibits three kinds of coordination modes involving two kinds of bridging conformations, resulting in four types of single-strand helical chains. The counter anions in the series of 2(1) helical silver(I) complexes {[Ag(L)]X}(infinity)(X = NO(3), 1; PF(6), 2; BF(4), 3; ClO(4), 4; CF(3)CO(2), 5; CF(3)SO(3), 6) are fully or partially embedded inside the cylindrical helix, and the pitch length corresponds not only to the size of the anion but also to its manner of docking into the groove of the helix. Formation of the helical structure in {[Cu(L)(CH(3)CN)(H(2)O)(ClO(4))]ClO(4)}(infinity)(7) is driven by Ow-H...O (perchlorate) hydrogen bonding that leads to a stable triangular motif which rigidly fixes the configuration of the helix. In {[Co(L)(H(2)O)(3)](ClO(4))(2).2H(2)O}(infinity)(8) and {[Zn(L)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(infinity)(9), similar helical chains without anion embedment suggest that the pitch length can be tuned by the size of metal cations. Notably, complex {[Ag(L)]CF(3)SO(3)}(infinity)(10), a conformational polymorph of , has a 4(1) helix induced by argentophilic interaction.     

Stepwise assembly of two 3d-4d heterometallic coordination polymers based on a hexanuclear silver(I) metalloligand

Two novel 3d-4d heterometallic coordination polymers {[Cu(3)(bipy)(3)(H(2)O)(5)][Ag(6)(mna)(6)]·11.5H(2)O}(n) (1) and {[Zn(3)(eda)(3)(H(2)O)(4)][Ag(6)(mna)(6)]·8H(2)O}(n) (2) were synthesized based on a hexanuclear silver(I) metalloligand by a three-step synthetic method (bipy = 2, 2'-bipyridine, eda = ethylenediamine and H(2)mna = 2-mercaptonicotinic acid). The photoluminescence behaviors of 1 and 2 were also discussed.     

Tuning the coordination geometry of silver in bis(pyrazolyl)alkane complexes

Silver(I) complexes of the bis(pyrazolyl)methane ligands Ph(2)C(pz)(2), PhCH(pz)(2), and PhCH(2)CH(pz)(2) (pz = pyrazolyl ring) have been prepared in an attempt to explore how sterically hindered poly(pyrazolyl)methane ligands influence the variable coordination geometries exhibited by silver(I) complexes, especially its ability to participate in cation...pi interactions. The complex (Ag[(pz)(2)CPh(2)](2))(PF(6)).C(3)H(6)O adopts an unusual square planar coordination environment as indicated by the sum of the four N-Ag-N angles being 360 degrees. The proximity of phenyl groups above and below the AgN(4) core enforces the unusual coordination geometry about the metal center. This arrangement is not a result of silver(I)...pi arene interactions but rather of the constraints imposed by the steric crowding caused by (aryl)(2)C(pz)(2) ligands. In contrast, the complexes of the other two ligands, (Ag[(pz)(2)CHPh](2))(PF(6)).0.5CH(2)Cl(2) and (Ag[(pz)(2)CH(CH(2)Ph)](2))(PF(6)).CH(2)Cl(2), show normal tetrahedral geometry about the silver(I), also with no indication of silver(I)...pi arene interactions. All three new complexes have extended supramolecular structures supported by a combination of CH...pi and CH...F interactions.     

Peculiarities of the complexation of copper and silver adducts of a 3,5-bis(trifluoromethyl)pyrazolate ligand with organoiron compounds

Interaction of the copper, {[3,5-(CF(3))(2)Pz]Cu}(3), and silver, {[3,5-(CF(3))(2)Pz]Ag}(3), macrocycles [3,5-(CF(3))(2)Pz = 3,5-bis(trifluoromethyl)pyrazolate] with cyclooctatetraeneiron tricarbonyl, (cot)Fe(CO)(3), was investigated by IR and NMR spectroscopy for the first time. The formation of 1:1 complexes was observed at low temperatures in hexane. The composition of the complexes (1:1) and their thermodynamic characteristics in hexane and dichloromethane were determined. The π-electron system of (cot)Fe(CO)(3) was proven to be the sole site of coordination in solution and in the solid state. However, according to the single-crystal X-ray data, the complex has a different (2:1) composition featuring the sandwich structure. The complexes of ferrocene with copper and silver macrocycles have a columnar structure (X-ray data).     

Crystal retro-engineering: structural impact on silver(I) complexes with changing complexity of tris(pyrazolyl)methane ligands

The preparation and structures of seven new silver(I) complexes involving the parent tris(pyrazolyl)methane unit, [C(pz)(3)], as the donor set, {[C6H5CH2OCH2C(pz)3]Ag}(BF4), {[C6H5CH2OCH2C(pz)3]2Ag3}(CF3SO3)3, {[HOCH2C(pz)3]Ag}(BF4), {[HOCH2C(pz)3]Ag}(CF3SO3), {[HC(pz)3]2Ag2(CH3CN)}(BF4)2, {[HC(pz)3]Ag}(PF6), and {[HC(pz)3]Ag}(CF3SO3), are reported. This project is based on a retro-design of our multitopic C6H(6-n)[CH2OCH2C(pz)3]n (pz = pyrazolyl ring, n = 2, 3, 4, and 6) family of ligands in such a way that each new ligand has one fewer organizational feature. The kappa2-kappa1 bonding mode of the [C(pz)3] units to two silvers, also observed with the multitopic ligands, is the dominant structural feature in all cases. Changing the counterion has important effects on the local structures and on crystal packing. When these structures are compared to similar ones based on the multitopic C6H(6-n)[CH2OCH2C(pz)3]n ligands, it has been shown that the presence of the rigid parts (central arene core and the [C(pz)3] units) are important in order to observe highly organized supramolecular structures. The presence of the flexible ether linkage is also crucial, allowing all noncovalent forces to manifest themselves in a cumulative and complementary manner.     

Mononuclear, dinuclear, hexanuclear, and one-dimensional polymeric silver complexes having ligand-supported and unsupported argentophilic interactions stabilized by pincer-like 2,6-bis(5-pyrazolyl)pyridine ligands

The mononuclear complexes [Ag(H2L1)(Py)2](NO3) x H2O (1, H2L1 = 2,6-bis(5-methyl-1H-pyrazol-3-yl)pyridine) and [Ag(NO3)(L()] (2, L2 = 2,6-bis(5-methyl-1-isopropyl-1H-pyrazol-3-yl)pyridine), dinuclear complex [Ag2(H2L3)2(HL4)2] (3, H2L3 = 2,6-bis(5-phenyl-1H-pyrazol-3-yl)pyridine, HL4 = 6-(5-phenyl-1H-pyrazolyl-3-yl)picolinate), one-dimensional polymer {[Ag2(H2L1)2](NO3)2 x H2O}(n) (4), and hexanuclear clusters [Ag6(HL1)4](X)2 (X = NO3-, 5 ; BF4-, 6 ; ClO4-, 7) stabilized by pincer-like bispyrazolyl ligands have been prepared and characterized using (1)H NMR spectroscopy, elemental analysis, IR spectroscopy, luminescence spectroscopy and X-ray diffraction. In complex , there is a ligand unsupported Ag-Ag bond between the two silver atoms. Complex displays a one-dimensional polymer consisting of an infinite Ag-Ag chain and every two adjacent silver ions are bridged by an H2L1 ligand. Complexes and have the same Ag6 cores in which six silver atoms are held together by four HL1 and five Ag-Ag bonds, while complex was held together by six Ag-Ag bonds. The silver-silver distances in these complexes are found in the range of 2.874(1)-3.333(2) A for ligand supported, and 3.040(1) A for ligand unsupported Ag-Ag bonds, respectively. Complexes 3-7 are strongly luminescent due to either intraligand or metal-ligand charge transfer processes.     

Cobalt(II)-(dpyo)-dicarboxylate networks: unique H-bonded assembly and rare bridging mode of dpyo in one of them [dpyo = 4,4'-dipyridyl N,N'-dioxide

Polymeric networks, {[Co(dpyo)(ox)]}(n) (1), {[Co(dpyo)(fum)(H(2)O)(2)]}(n) (1) and {[Co(dpyo)(tp)(H(2)O)(2)] x [Co(H(2)O)(6)] x (tp) x (H(2)O)}(n) (3) [ox = oxalate dianion, fum = fumarate dianion, tp = terephthalate dianion and dpyo = 4,4'-dipyridyl N,N'-dioxide] have been synthesized and characterized by single crystal X-ray diffraction analyses. The structural determination reveals 1 and 2 are covalent bonded 2D networks of 4,4 topology and of these, complex 2 undergoes a H-bonding scheme resulting in a 3D supramolecular architecture. Complex 3 is a 1D coordination polymer built up by almost collinear hexacoordinated Co(ii), doubly bridged by a tp carboxylate group and a dpyo oxygen, which in combination with lattice [Co(H(2)O)(6)](2+), tp and water molecules shows an unprecedented 3D supramolecular network through H-bonding. In the polymer the dpyo shows novel mu-4,4 bridging mode towards the cobalt ion. Low temperature magnetic interaction reveals antiferromagnetic coupling in all of the complexes.     

Assembly of discrete,one-, two-, and three-dimensional silver(I) supramolecular complexes containing encapsulated acetylide dianion with nitrogen-donor spacers

The first successful attempt to construct supramolecular entities via incorporation of bifunctional exodentate ligands into the silver acetylide system is reported. Coordination assembly with nitrogen-donor spacers led to the formation of five distinct supramolecular complexes, namely [(Ag(2)C(2))(AgCF(3)CO(2))(4)(pyz)(2)](n) (1), [(Ag(2)C(2))(2)(AgCF(3)CO(2))(10)(CF(3)CO(2))(4)(DabcoH)(4)(H(2)O)(1.5)].H(2)O (2), [(Ag(2)C(2))(AgCF(3)CO(2))(4)(CF(3)CO(2))(bpaH)](n)() (3), [(Ag(2)C(2))(AgCF(3)CO(2))(8)(bpa)(4)](n) (4), and [(Ag(2)C(2))(2)(AgCF(3)CO(2))(10)(bppz)(2)(H(2)O)](n) (5) (pyz = pyrazine; Dabco = 1,4-diazabicyclo[2.2.2]octane; bpa = 1,2-bis(4-pyridyl)ethane; bppz = 2,3-bis(2-pyridyl)pyrazine). Complex 1 is a three-dimensional framework composed of silver columns cross-linked by pyrazine bridges, whereas 2 contains a discrete supermolecule whose core is a Ag(14) double cage that is completely surrounded by trifluoroacetate, aqua, and terminal monoprotonated Dabco ligands. Complex 3 has a branched-tree architecture with one terminal of the bpa ligand attached to the silver backbone and the other exposed and protonated. In 4, neutral decanuclear [(Ag(2)C(2))(AgCF(3)CO(2))(8)] units are interlinked by bpa spacers adopting both gauche and anti conformations to generate a layer structure. Another two-dimensional network was formed with bppz serving as an angular bridging ligand in 5, in which the building unit is a silver quadruple cage containing 24 silver atoms.     

Two- and three-dimensional silver(I)-organic networks generated from mono- and dicarboxylphenylethynes

Three phenylethynes bearing methyl carboxylate (HL1), monocarboxylate (H(2)L2), and dicarboxylate (H(2)L3) groups were utilized as ligands to synthesize a new class of organometallic silver(I)-ethynide complexes as bifunctional building units to assemble silver(I)-organic networks. X-ray crystallographic studies revealed that in [Ag(2)(L1)(2)·AgNO(3)](∞) (1) (L1= 4-C(2)C(6)H(4)CO(2)CH(3)), one ethynide group interacts with three silver ions to form a complex unit. These units aggregate by sharing silver ions with the other three units to afford a silver column, which are further linked through argentophilic interaction to generate a two-demensional (2D) silver(I) network. In [Ag(2)(L2)·3AgNO(3)·H(2)O](∞) (2) (L2 = 4-CO(2)C(6)H(4)C(2)), the ethynide group coordinates to four silver ions to form a building unit (Ag(4)C(2)C(6)H(4)CO(2)), which interacts through silver(I)-carboxylate coordination bonds to generate a wave-like 2D network and is subsequently connected by nitrate anions as bridging ligands to afford a three-demensional (3D) network. In [Ag(3)(L3)·AgNO(3)](∞) (3) (L3 = 3,5-(CO(2))(2)C(6)H(3)C(2)), the building unit (Ag(4)C(2)C(6)H(3)(CO(2))(2)) aggregates to form a dimer [Ag(8)(L3)(2)] through argentophilic interaction. The dimeric units interact through silver(I)-carboxylate coordination bonds to directly generate a 3D network. The obtained results showed that as a building unit, silver(I)-ethynide complexes bearing carboxylate groups exhibit diverse binding modes, and an increase in the number of carboxylate groups in the silver(I)-ethynide complex unit leads to higher level architectures. In the solid state, all of the complexes (1, 2, and 3) are photoluminescent at room temperature.