Four Polyoxometalate-Viologen Discoloration Materials for UV Probing,Inkless and Erasable Printing and Visual Detection of Hg2+

In this work, four POM-based compounds containing viologen ligands were synthesized, namely {Cu^II(tybipy)₂(DMF)₂[H₂(β-Mo₈O₂₆)]₂} ⋅ 4 C₂H₇N ( 1 ), (Htybipy)₂ ⋅ (β-Mo₈O₂₆) ( 2 ) (tybipy⋅Br=1-Thiophen-3-ylmethyl-[4,4’]bipyridinyl-1-ium bromide), [Cu^II(nibipy)₂(4,4’-bipy)] ⋅ (SiW₁₂O₄₀) ( 3 ), (Hnibipy)₂ ⋅ (δ-Mo₈O₂₆) ( 4 ) (nibipy⋅Cl=1-(4-Nitro-benzyl)-[4,4’]bipyridinyl-1-ium chloride, 4,4’-bipy=4,4’-bipyridine). In compounds 1 and 3 , Cu²⁺ and mixed organic ligands modify POM anions. On the other hand, 2 and 4 are supramolecular structures only containing ligands and anions. Under Xe lamp with filter (300-400 nm) irradiation, these four compounds showed good photoresponse and photochromic ability, which can be used in mixed matrix films for visible UV detectors. Compounds 1 – 4 also have photoluminescence property and show good fluorescence quenching effect. A suspension of four compounds can be evenly spread on filter paper as inkless and erasable printing materials. Compounds 1 and 2 were also used as Hg²⁺ fluorescence detectors. The fluorescence intensity of 1 decreased by ca. 90 % when the concentration of Hg²⁺ increased to 40 mM. Moreover, we also prepared composites 1 / 2 @Hg²⁺, 1 @Cu²⁺, 1 @Co²⁺ by introducing 1 / 2 and Hg²⁺, Cu²⁺ and Co²⁺ to detection paper respectively, which can act as photochromic materials with features of fast color recovery.     

Hydrothermal synthesis,crystal structure and fluorescence of a 3D organic–inorganic hybrid coordination network [CuI(4,4′-bipy)]4[ δ -Mo8O26] exhibiting an interesting polymorphism

A new three-dimensional (3D) extended solid [Cu^I(4,4′-bipy)]₄[δ-Mo₈O₂₆] (1) built on {Cu(4,4′-bipy)}⁺ (bipy?=?bipyridine) and isopolymolybdate anion [δ-Mo₈O₂₆]^4? has been synthesized and characterized by elemental analysis, IR, TG, X-ray powder diffraction and single-crystal X-ray diffraction analysis. Compound 1 shows six coppers bonded to [δ-Mo₈O₂₆]^4? to form inorganic planes which are linked by 4,4′-bipy into a 3D network, the first example of [δ-Mo₈O₂₆]^4? six-connected linkage based on an organic-inorganic coordination polymer. A polymorphism of compound 1 was found which has an identical molecular formula but absolutely different structure. The influence of the synthesis conditions of 1 has been studied. Furthermore, the fluorescence of 1 is reported.     

The assembly of POM-induced inorganic–organic hybrids based on copper ions and mixed ligands

Three inorganic–organic hybrid materials based on Keggin-type polyoxometalates (POMs), [Cu^II₂(phen)₂(4,4′-bipy)(H4,4′-bipy)₂(H₂O)₂][PMo₁₂O₄₀]₂·2H₂O (1), [Cu^II(phen)₂(H4,4′bipy)][PW₁₂O₄₀]·H₂O (2), and [Cu^II₂(phen)₂(4,4′-bipy)(BW₁₂O₄₀)(H₂O)₂](H₂4,4′-bipy)_0.5·3H₂O (3) (phen = 1,10-phenanthroline, 4,4′-bipy = 4,4′-bipyridine), were synthesized using different POMs in the hydrothermal conditions. Compounds 1–3 were characterized by single-crystal X-ray diffraction, IR spectra, elemental analyses, powder X-ray diffraction analyses, and thermogravimetric analyses. Compound 1 presents a two-dimensional (2-D) network containing the Keggin-type [PMo₁₂O₄₀]^3? anion and dinuclear metal–organic units [Cu^II₂(phen)₂(4,4′-bipy)(H4,4′-bipy)₂(H₂O)₂]³⁺. Compound 2 is a 2-D architecture constructed from a [PW₁₂O₄₀]^3? and mononuclear metal–organic units [Cu^II(phen)₂(H4,4′-bipy)]³⁺. In 3, the [BW₁₂O₄₀]^5? anions link [Cu^II₂(phen)₂(4,4′-bipy)] units to form a one-dimensional (1-D) chain [Cu^II₂(phen)₂(4,4′-bipy)(BW₁₂O₄₀)(H₂O)₂]; the 1-D chain connects with protonated 4,4′-bipy ligands and lattice waters, yielding a 2-D layer. Fluorescence spectra, UV–vis spectra, and electrochemical properties of 1–3 have been investigated.     

Silver(I) sulfate coordination polymers with 4,4′‐bipyridazine and pyridazino[4,5‐d]pyridazine

Poly[[μ₄‐4,4′‐bipyridazine‐μ₅‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₈H₆N₄)]·H₂O}_n, (I), and poly[[aqua‐μ₄‐pyridazino[4,5‐d]pyridazine‐μ₃‐sulfato‐disilver(I)] monohydrate], {[Ag₂(SO₄)(C₆H₄N₄)(H₂O)]·H₂O}_n, (II), possess three‐ and two‐dimensional polymeric structures, respectively, supported by N‐tetradentate coordination of the organic ligands [Ag—N = 2.208 (3)–2.384 (3) Å] and O‐pentadentate coordination of the sulfate anions [Ag—O = 2.284 (3)–2.700 (2) Å]. Compound (I) is the first structurally examined complex of the new ligand 4,4′‐bipyridazine; it is based upon unprecedented centrosymmetric silver–pyridazine tetramers with tetrahedral AgN₂O₂ and trigonal–bipyramidal AgN₂O₃ coordination of two independent Ag^I ions. Compound (II) adopts a typical dimeric silver–pyridazine motif incorporating two kinds of square‐pyramidal AgN₂O₃ Ag^I ions. The structure exhibits short anion–π interactions involving noncoordinated sulfate O atoms [O...π = 3.041 (3) Å].     

A one-dimensional organic–inorganic hybrid constructed by saturated Keggin polyoxoanions and [CuI(4,4′-bipy)] n n + chains

A one-dimensional (1-D) organic–inorganic hybrid compound {(H₃O)[Cu^I(4,4′-bipy)]₃[SiW₁₂O₄₀]} · 1.5H₂O (1) has been synthesized from hydrothermal reaction of Keggin polyoxometalate, cupric nitrate and 4,4′-bipyridine (4,4′-bipy). Single crystal X-ray diffraction shows 1-D zigzag chains built up of saturated Keggin polyoxoanions and infinite [Cu^I(4,4′-bipy)] _n ^{n +} units. Zipper-like arrangement of adjacent zigzag chains by hydrogen-bonding interactions leads to a 2-D layer and π–π interactions of 4,4′-bipy ligands from adjacent layers further result in the 3-D structure of 1. All Cu atoms in 1 are three-coordinated with “T-type” geometries, indicating they are univalent in the resultant compound. This result has further been confirmed by the absence of signal in the EPR spectrum of 1.     

Constructing mixed‐metal coordination polymers from copper(II)–pyridinedicarboxylate metalloligands

In the mixed‐metal complex catena‐poly[bis[diaquasilver(I)] [bis[aquacopper(II)]‐μ₃‐pyridine‐2,5‐dicarboxylato‐2′:1:1′κ⁵N,O²:O⁵:O⁵,O^5′‐μ‐pyridine‐2,5‐dicarboxylato‐2:1κ⁴N,O²:O⁵,O^5′‐disilver(I)‐μ₃‐pyridine‐2,5‐dicarboxylato‐1:1′:2′′κ⁵O⁵,O^5′:O⁵:N,O²‐μ‐pyridine‐2,5‐dicarboxylato‐1′:2′′′κ⁴O⁵,O^5′:N,O²] hexahydrate], {[Ag(H₂O)₂][AgCu(C₇H₃NO₄)₂(H₂O)]·3H₂O}_n, a square‐pyramidal Cu^II center is coordinated by two N atoms and two O atoms from two pyridine‐2,5‐dicarboxylate (2,5‐pydc) ligands and a water molecule, forming a [Cu(2,5‐pydc)₂(H₂O)]²⁻ metalloligand. One Ag^I center is coordinated by five O atoms from three 2,5‐pydc ligands and, as a result, the [Cu(2,5‐pydc)₂(H₂O)]²⁻ metalloligands act as linkers in a unique μ₃‐mode connecting Ag^I centers into a one‐dimensional anionic double chain along the [101] direction. The other Ag^I center is coordinated by two water molecules, forming an [Ag(H₂O)₂]⁺ cation. Four adjacent Ag^I centers are associated by Ag...Ag interactions [3.126 (1) and 3.118 (1) Å], producing a Z‐shaped Ag₄ unit along the [010] direction and connecting the anionic chains into a two‐dimensional layer structure. This study offers information for engineering mixed‐metal complexes based on copper(II)–pyridinedicarboxylate metalloligands.     

A Doubly Interpenetrated Cu(II)-based Metal-Organic Framework as a Heterogeneous Catalyst for the ipso-Hydroxylation of Arylboronic Acids

A doubly interpenetrated Cu(II)-organic framework with formula [{Cu₂( L )₂(4,4′-bpdc)₂(H₂O)₂} ⋅ 8H₂O ⋅ CH₃OH]_α ( 1 ) (where, L =N², N⁶-di(pyridin-4-yl)naphthalene-2,6-dicarboxamide and 4,4′-bpdc=[1,1′-biphenyl]-4,4′-dicarboxylate ion) has been synthesized and characterized with the help of several spectroscopic and analytical techniques including single crystal X-ray analysis. A single crystal X-ray analysis reveals that 1 exhibit interpenetrated two-dimensional sheet-like structure containing elongated channels of cross-section 11.09×31.22 Ų along the a-axis. Finally, 1 has been exploited as a heterogeneous catalyst for the ipso-hydroxylation of arylboronic acids yielding up to 99 % of the respective phenolic product. Importantly, the catalyst can be reused for five successive cycles without having a significant loss in its catalytic efficiency.     

Synthesis,Crystal Structures,and Photoluminescence of Lanthanide Coordination Polymers with 4‐Acetamidobenzoate

The reactions of Ln(NO₃)₃ · 6H₂O and 4‐acetamidobenzoic acid (Haba) with 4,4′‐bipyridine (4,4′‐bpy) in ethanol solution resulted in three new lanthanide coordination polymers, namely {[Ln(aba)₃(H₂O)₂] · 0.5(4,4′‐bpy) · 2H₂O}_∞ [Ln = Sm ( 1 ), Gd ( 2 ), and Er ( 3 ), aba = 4‐acetamidobenzoate]. Compounds 1 – 3 are isomorphous and have one‐dimensional chains bridged by four aba anions. 4,4′‐Bipyridine molecules don’t take part in the coordination with Ln^III ions and occur in the lattice as guest molecules. Moreover, the adjacent 1D chains in the complex are further linked through numerous N–H ··· O and O–H ··· O hydrogen bonds to form a 3D supramolecular network. In addition, complex 1 in the solid state shows characteristic emission in the visible region at room temperature.     

Solvothermal Synthesis,Crystal Structure,and Photocatalytic H2 Evolution of two CuII Coordination Polymers Based on Keggin Polyoxotungstates

Two new Cu^II coordination polymers based on α‐Keggin polyoxotungstates, [Cu₂(dpa)₂(H₂O)₂(GeW₁₂O₄₀)] · 0.5CH₃COOH ( 1 ) and [Hdpa][Cu₂(dpa)₂(4,4′‐bipy)(H₂O)₂(PW₁₀V₂O₄₀)] ( 2 ) (dpa = 2,2′‐dipyridylamine, 4,4′‐bipy = 4,4′‐bipyridine), were obtained by solvothermal reactions in glacial acetic acid and characterized by elemental analysis, IR spectroscopy, TG analysis, X‐ray powder diffraction, and single‐crystal X‐ray diffraction. Compound 1 exhibits a 1D two‐rowed chain constructed from [GeW₁₂O₄₀]^4– anions coordinated with [Cu(1)(dpa)]²⁺ and [Cu(2)(dpa)(H₂O)₂]²⁺ fragments by four terminal oxygen atoms. Compound 2 exhibits a 2D layered structure constructed from [PW₁₀V₂O₄₀]^5– anions coordinated with [Cu(dpa)(4,4′‐bipy)_0.5(H₂O)]²⁺ fragments by four terminal oxygen atoms. Furthermore, the electrochemical properties of 1 and the photocatalytic hydrogen production of 1 and 2 were investigated.     

catena‐Poly[bis[silver(I)‐μ2‐4,4′‐bipyridine‐κ2N:N′] naphthalene‐2,6‐dicarboxylate tetrahydrate]: self‐assembly of a supramolecular framework via coordination bonds and supramolecular interactions

The ultrasonic reaction of AgNO₃, 4,4′‐bipyridine (bipy) and naphthalene‐2,6‐dicarboxylic acid (H₂NDC) gives rise to the title compound, {[Ag₂(C₁₀H₈N₂)₂](C₁₂H₆O₄)·4H₂O}_n. The NDC dianion is located on an inversion centre. The Ag^I centre is coordinated in a linear manner by two N atoms from two bipy ligands. The crystal structure consists of one‐dimensional Ag^I–bipy cationic chains and two‐dimensional NDC–H₂O anionic sheets, constructed by coordination bonds and supramolecular interactions, respectively.     

A Tray‐Shaped,PdII‐Clipped Au3 Complex as a Scaffold for the Modular Assembly of [3×n] Au Ion Clusters

A tray‐shaped Pd^II₃Au^I₃ complex ( 1 ) is prepared from 3,5‐bis(3‐pyridyl)pyrazole by means of tricyclization with Au^I followed by Pd^II clipping. Tray 1 is an efficient scaffold for the modular assembly of [3×n] Au^I clusters. Treatment of 1 with the Au^I₃ tricyclic guest 2 in H₂O/CH₃CN (7:3) or H₂O results in the selective formation of a [3×2] cluster ( 1 ⋅ 2 ) or a [3×3] cluster ( 1 ⋅ 2 ⋅ 1 ), respectively. Upon subsequent addition of Ag^I ions, these complexes are converted to an unprecedented Au₃–Au₃–Ag–Au₃–Au₃ metal ion cluster.     

Metal–organic Coordination Polymers Assembled from Divalent Transition Salts with a Flexible Spacer Ligand: Hydrothermal Syntheses,Crystal Structures,and Luminescent and Magnetic Properties

Seven new metal-organic coordination polymers, [M(tzda)(H₂O)₄] _n [M = Co(1), Ni (2) and Zn(3)], [Zn(tzda)(4,4′-bipy)] _n (4), [Cd(tzda)(4,4′-bipy)_0.5(H₂O)] _n (5) and [M(tzda)(4,4′-bipy)(H₂O)] _n [M = Co(6), Ni(7)] [H₂tzda = (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally synthesized and structurally characterized by X-ray single crystal diffraction. Compounds 1–3 display similar 1D zigzag chain structure. Compound 4 possesses a 2D-layered architecture generated from [Zn(tzda)] _n moiety with double-chain structure cross-linking 4,4′-bipy spacers, while compound 5 consists of –Cd–OCO–Cd–OCO– chains cross-linked through –CH₂SC₂N₂SSCH₂– spacers of tzda anions and 4,4′-bipy, also showing a 2D-layered structure. The structures of 6 and 7 seem more complicated, in which the [M(tzda)] _n layered subunits are extended to unique 3D framework by the bridging 4,4′-bipy ligand. Photoluminescence investigations reveal that 4 and 5 both display strong blue emissions in the solid state at room temperature, which could be significant in the field of luminescent materials. The magnetic studies of 6 and 7 show both display the characteristics of a weak antiferromagnetic coupling between metal ions in the system mediated by carboxylate bridges.     

Two new polyoxometalate-based organic-inorganic hybrids: synthesis,crystal structure and characterization

Two new organic-inorganic hybrids, (4,4′-bipy)[Cu^I(2,2′-bipy)₂]₂[W₆O₁₉] (2,2′-bipy = 2,2′-bipyrine, 4,4′-bipy = 4,4′-bipyrine) (1) and (C₆H₅NO₂)₄{Mn^III(H₂O)}[As^IIIW₉O₃₃]₂{W(OH)}- {W(H₂O)}?～18H₂O (2), have been synthesized and characterized by elemental analysis, IR, TG, UV–Vis, XRPD, XPS, electrochemical analysis and single-crystal X-ray diffraction. Single crystal X-ray diffraction analysis shows that 1 is a new Lindqvist-type polyoxoanion bisupported by copper(I) coordination cations and 2,2′-bipy ligands and exhibits a three-dimensional (3-D) supermolecular framework by aromatic π–π stacking interactions. Compound 2 is constructed from a manganese(III)-substituted sandwich-type polyoxoanion based on [α-AsW₉O₃₃]^9? units and dissociative, protonated pyridine-4-carboxylic acid molecules, which act as the charge compensation cations. The cyclic voltammogram of 2 shows an irreversible redox process for Mn³⁺ ions.     

Poly[bis(μ2‐2‐aminopyrazine‐κ2N1:N4)(μ2‐nitrato‐κ2O:O)(nitrato‐κ2O,O′)disilver(I)]: an achiral two‐dimensional coordination polymer forming chiral crystals

The solution reaction of AgNO₃ and 2‐aminopyrazine (apyz) in a 1:1 ratio gives rise to the title compound, [Ag₂(NO₃)₂(C₄H₅N₃)₂]_n, (I), which possesses a chiral crystal structure. In (I), both of the crystallographically independent Ag^I cations are coordinated in tetrahedral geometries by two N atoms from two apyz ligands and two O atoms from nitrate anions; however, the Ag^I centers show two different coordination environments in which one is coordinated by two O atoms from two different symmetry‐related nitrate anions and the second is coordinated by two O atoms from a single nitrate anion. The crystal structure consists of one‐dimensional Ag^I–apyz chains, which are further extended by μ₂‐κ²O:O nitrate anions into a two‐dimensional (4,4) sheet. N—H...O and C_apyz—H...O hydrogen bonds connect neighboring sheets to form a three‐dimensional supramolecular framework.     

Three Distinct Silver(I) Coordination Polymers: Bridging‐­Ligand Directed Syntheses,Crystal Structures,Luminescence, and Nitrobenzene Sensing Properties

Three distinct Ag^I‐DMAP [DMAP = 4‐(dimethylamino)pyridine] coordination polymers [Ag₂I₂(DMAP)₂]_n ( 1 ), [Ag₂(CN)₂(DMAP)_2.5 · DMAP]_n ( 2 ), and [Ag(SCN)(DMAP)]_n ( 3 ) were constructed by monatomic I^–, diatomic CN^–, and triatomic SCN^– bridges, respectively. 1 – 3 were determined by FT‐IR spectroscopy, elemental analyses, TGA, powder and single‐crystal X‐ray diffraction. 1 exhibits a 1D wavelike chain structure, sustained by 3‐connected I^– bridges, whereas 2 shows a unique 1D single‐ and double‐strand alternating chain, supported by 3‐connected CN^– bridges. Compound 3 has a 2D 3‐connected network architecture, fabricated by 3‐connected SCN^– bridges, and exhibits a (4 · 8²) topology. The luminescence and nitrobenzene sensing properties of 1 – 3 were explored in 2‐propanol suspensions, which revealed that compounds 1 – 3 exhibit DMAP originated luminescence emissions and are highly sensitive for nitrobenzene detection.     

Hydrothermal syntheses, crystal structures and properties of 0-D, 1-D and 2-D organic-inorganic hybrid borotungstates constructed from Keggin-type heteropolyanion [α-BW12O40] and transition-metal complexes

Three novel organic-inorganic hybrid borotungstates {[Ni(phen)₂(H₂O)]₂H(α-BW₁₂O₄₀)}·4H₂O (1), [Cu^I(2,2'-bipy)(4,4′-bipy)_0.5]₂{[Cu^I(2,2′-bipy)]₂Cu^I(4,4′-bipy)₂(α-BW₁₂O₄₀)} (2) and {[Cu^I(4,4′-bipy)]₃H₂(α-BW₁₂O₄₀)}·3.5H₂O (3) (phen=1,10-phenanthroline, 2,2′-bipy=2,2′-bipyridine, 4,4′-bipy=4,4′-bipyridine) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), single-crystal X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and photoluminescence. The structural analysis reveals that 1 consists of a 0-D bisupporting polyoxometalate cluster where two [Ni(phen)₂(H₂O)]²⁺ cations are grafted on the polyoxoanion [α-BW₁₂O₄₀]^5- through two terminal oxygen atoms, 2 shows a 1-D infinite chain constructed from [α-BW₁₂O₄₀]^5- polyoxoanions and {[Cu^I(2,2′-bipy)]₂Cu^I(4,4′-bipy)₂}³⁺ cations by means of alternating fashion, and 3 displays an unprecedented 2D extended structure built by [α-BW₁₂O₄₀]^5- polyoxoanions and -Cu^I-4,4′-bipy- linear chains, in which each [α-BW₁₂O₄₀]^5- polyoxoanion acts as a tetradentate inorganic ligand and provides three terminal oxygen atom and one two-bridging oxygen atom. The presence of Ni^II and W^VI in 1, Cu^I ions and W^VI in 2 and 3 are identified by XPS spectra. The photoluminescence of 2 and 3 are also investigated.     

Hydrothermal synthesis and structure characterization of a new organic–inorganic composite (4,4′-H2bipy)2(4,4′-hbipy)2(ZnW12O40)·6H2O

A new organic–inorganic composite (4,4′-H₂bipy)₂(4,4′-Hbipy)₂(ZnW₁₂O₄₀)·6H₂O has been prepared by hydrothermal reaction and characterized by elemental analysis, IR and UV spectra, thermal analysis and single-crystal X-ray structural analysis. It belongs to the monoclinic system, space group P2₁/c, with a?=?18.637(4), b?=?14.003(3), c?=?26.470(5)?Å, β?=?104.78(3)°, V?=?6680(2)?ų, Z?=?4. Structural analysis indicates that the title complex consists of a Keggin anion [ZnW₁₂O₄₀]^6?, 4,4′-bipyridine and water of crystallization, constructing a supramolecular system through hydrogen bonding interactions. Thermal analysis shows that the heteropolyanion [ZnW₁₂O₄₀]^6? starts to decompose at 587.0°C.     

Syntheses and characterization of three hybrid materials based on polymeric copper complexes and saturated Keggin polyoxoanions

Three novel heteropolytungstates, [Cu(phen)₂]₄[α-SiW₁₂O₄₀] (1), [Cu₄(4,4′-bpy)₃(2,2′-bpy)₄][α-SiW₁₂O₄₀] · H₂O (2) and [Cu(4,4′-bpy)(4,4′-Hbpy)_0.5]₂[PW₁₂O₄₀] (3) (phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine), have been synthesized and characterized by elemental analyses, IR, TG analyses and single-crystal X-ray diffraction. Compound (1) exhibits interesting chiral layer constructed from interperpendicular helical chains running along a crystallographic 2₁ axis in the c and a directions. Furthermore, the chiral layers are connected by the [α-SiW₁₂O₄₀]⁴⁻ anions via hydrogen bonding interactions to form a 3D superamolecular structure. The [Cu₄(4,4′-bpy)₃(2,2′-bpy)₄]⁴⁺ coordinated complexes in compound (2) are packed together via the aromatic π–π stacking interactions and exhibit an interesting 3D sandglasslike “host” network with 1D channels, in which [α-SiW₁₂O₄₀]⁴⁻ anions “guests” reside. Compound (3) has a unique 2D superamolecular network, which is composed of cationic Cu^I coordination polymer chains and discrete [PW₁₂O₄₀]³⁻ polyoxoanions as linkers. It is noteworthy that the monprotonated 4,4′-bpy ligands of (3) act as arms and connect the adjacent 2D network, generating a 3D interpenetrating superamolecular structure.     

Fluorescent Properties of Three Carboxyarylphosphonate Polymers with Unusual Polynuclear Zinc(II) Units

Three novel carboxyarylphosphonate polymers {[Zn₂(PCP)(H₂PCP)(phen)₂] · H₂O}_n ( 1 ), [Zn(HPCP)(4,4′‐bipy)]_n ( 2 ), and [Zn₃(MCP)₂(2,2′‐bipy)]_n ( 3 ) [PCP^3– = p‐O₂C(C₆H₄)CH₂PO₃^3–, MCP^3– = m‐O₂C(C₆H₄)CH₂PO₃^3– and phen = phenanthroline] were synthesized and characterized by single‐crystal X‐ray diffraction. Compound 1 features a butterfly‐shaped dimer consisting of [Zn₄P₄O₁₀] tetranuclear units, which are further linked by hydrogen bonds and π–π stacking interactions into a 3D supramolecular framework. In 2 , there is an infinite P–O–Zn inorganic 2D (4,4) layer with the phosphonate moieties of HPCP^2– and unidentate 4,4′‐bipy ligands vertically sticking out. As for 3 , the novel [Zn₆P₄O₁₂] hexanuclear units with “chair“ conformation are tetrahedrally bridged by eight MCP^3– to generate a 2D double‐layer, in which the windows are occupied by 2,2′‐bipy molecules. Additionally, 2D correlation analysis of FTIR with thermal perturbation of 3 were discussed. Compounds 1 – 3 exhibit intense solid state fluorescent emissions. Thermogravimetric analyses suggested the very high stability.     

The Effect of Guest Metal Ions on the Reduction Potentials of Uranium(VI) Complexes: Experimental and Theoretical Investigations

Two mononuclear uranyl complexes, [UO₂L¹] ( 1 ) and [UO₂L²] ⋅ 0.5 CH₃CN ⋅ 0.25 CH₃OH ( 2 ), have been synthesized from two multidentate N₃O₄ donor ligands, N,N′-bis(5-methoxysalicylidene)diethylenetriamine (H₂L¹) and N,N′-bis(3-methoxysalicylidene)diethylenetriamine (H₂L²), respectively, and have been structurally characterized. Both complexes 1 and 2 showed a reversible U^VI/U^V couple at −1.571 and −1.519 V, respectively, in cyclic voltammetry. The reduction potential of the U^VI/U^V couple shifted towards more positive potential on addition of Li⁺, Na⁺, K⁺, and Ag⁺ metal ions to acetonitrile solutions of complex 2 , and the resulting potential was correlated with the Lewis acidity of the metal ions and was also justified by theoretical DFT calculations. No such shift in reduction potential was observed for complex 1 . All four bimetallic products, [UO₂L²Li_0.5](ClO₄)_0.5 ( 3 ), [UO₂L²Na(ClO₄)]₂ ( 4 ), [UO₂L²Ag(NO₃)(H₂O)] ( 5 ), and [(UO₂L²)₂K(H₂O)₂]PF₆ ( 6 ), formed on addition of the Li⁺, Na⁺, Ag⁺, and K⁺ metal ions, respectively, to acetonitrile solutions of complex 2 , were isolated in the solid state and structurally characterized by single-crystal X-ray diffraction. In all the species, the inner N₃O₂ donor set of the ligand encompasses the equatorial plane of the uranyl ion and the outer open compartment with O₂O′₂ donor sites hosts the second metal ion.