Tracking the Transformation Process of a Pair of Zn(II) Coordination Clusters: Crystallography and Mass Spectrometry

Two zinc clusters Zn₄(H₃L)₄(NO₃)₄?5H₂O ( Zn₄ , H₄L=(1,2‐bis(1H‐benzo[d]imidazol‐2‐yl)ethane‐1,2‐diol) and [Zn₅(H₂L′)₆](NO₃)₄]?8H₂O?2CH₃OH ( Zn₅ , H₃L′=(1,2‐bis(benzo[d] imidazol‐2‐yl)‐ethenol) have been obtained by the reaction of Zn(NO₃)₂?6H₂O with H₄L at 80 °C or 140 °C under solvothermal condition. Powder X‐ray Diffraction (PXRD) of precipitate and Electrospray Ionization Mass Spectrometry (ESI‐MS) of reaction solution revealed the existence of transformation behavior from Zn₄ to Zn₅ by increasing the temperature from 80 °C to 140 °C, or directly heating Zn₄ at 140 °C via solvothermal reaction. Here we proposed a possible mechanism involves split process of Zn₄ and reassembly to form Zn_{5 .} ESI‐MS for single crystals revealed [Zn₄(H₃L)₄?3H]⁺ splits to [Zn(H₃L)]⁺ via [Zn₂(H₃L)₂?H]⁺. Time dependent ESI‐MS of reaction solution revealed the [Zn(H₂L′)]⁺→[Zn₂(H₂L′)₂?H]⁺→[Zn₅(H₂L′)₆?H]³⁺ stepwise assembly. It also has been captured the in situ reaction mainly occurs in the step of [Zn(H₃L)]⁺ to [Zn(H₂L′)]⁺.     

A pair of novel helical Zn(II) enantiomers constructed from l- and d-threonine Schiff bases: Synthesis,crystal structures and properties

Two novel homochiral helical Zn(II) coordination polymers, {[Zn₂(nap-l-thr)₂(H₂O)₂]·H₂O}_n (1) and {[Zn₂(nap-d-thr)₂(H₂O)₂]·H₂O}_n (2) (H₂nap-l-thr = N-(2-hydroxy-1-naphthylmethylidene)-l-threonine, H₂nap-d-thr = N-(2-hydroxy-1-naphthylmethylidene)-d-threonine) have been successfully synthesized and characterized by elemental analysis, IR, UV–visible and single-crystal X-ray diffraction. It is interesting to note that both complexes are a pair of enantiomers: 1 exhibits 1D right-handed helical chain of [Zn-COO⁻]_∞ and 2 is 1D left-handed helical chain of [Zn-COO⁻]_∞. There are various hydrogen bonds between the adjacent helical chains which result in a 2D homochiral supramolecular layer structure. Notably, under similar synthetic procedure by using the NO₃⁻, CH₃COO⁻, Cl⁻ salts of Zn^2 + ion as a starting reagent, and identical compounds were obtained. In addition, the chiral nature of complexes 1 and 2 are confirmed by the results of circular dichroism (CD) spectra measurements. Thermal stability and luminescence properties were also investigated.     

One novel polynuclear complex [Cu2(bpc)2(N3)4Ca(H2O)2Na2(H2O)2]n having three different transition and non-transition metal centres

The complex [Cu₂(bpc)₂(N₃)₄Ca(H₂O)₂Na₂(H₂O)₂]_n (1) (bpc²⁻=2,2^′-bipyridyl-3,3^′-dicarboxylate) has been prepared and characterised by elemental analyses, spectroscopic and single crystal X-ray diffraction study. Single crystal X-ray analysis revealed a novel polynuclear complex containing three different metal centres such as an alkali metal (sodium), an alkaline earth metal (calcium) and a transition metal atom (copper) connected together by azide and carboxylato groups.     

Solvent directed assembly of two zinc(II)-2-(4-pyridyl)-4,5-imidazoledicarboxylate frameworks

Two zinc(II)-2-(4-pyridyl)-4,5-imidazoledicarboxylate frameworks, formulated as {[Zn₃(HPIDC)₃(DMF)₂](DMF)₂(H₂O)₂}_n (1) and {[Zn₄(HPIDC)₄(DMF)₄](DMF)₂(FMA)₂(H₂O)}_n (2) (H₃PIDC = 2-(4-pyridyl)-1H-4,5-imidazoledicarboxylic acid, DMF = N,N′-dimethylformamide, FMA = formamide) have been solvothermally synthesized depending on whatever solvents are used. In both structures, the HPIDC^2 − anions act as tripodal connectors to chelating with three zinc(II) cations while the zinc(II) cations coordinate with three HPIDC^2 − anions, to form the T-shape molecular building blocks [Zn_n(HPIDC)_n], which further connect in interdigitating or alternating fashion to result in the assembly of two different 3,3-connected networks. The luminescence behaviors and solvent effect were also discussed.     

Construction of three new mixed-ligand Zn(II) coordination polymers based on nitrogen-containing heterotopic ligands and carboxylate co-ligands

Reactions of Zn(II) salts, presynthesized 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and various carboxylate ligands result to three new coordination polymers (CPs), namely, [Zn₂[(IPT)₂(ox)]}_n (H₂ox = oxalic acid, 1), [Zn₂(IPT)₂(mNBDC)]_n (H₂mNBDC = 5-nitroisophthalic acid, 2), and [Zn₂(IPT)(CA)(H₂O)]_n (H₃CA = citric acid, 3). Compound 1 can be seen as constructed from 2D [Zn(IPT)]_n layers with (6,3) topology and pillared by ox^2 −. It is a 3D (3,4)-connected framework with InS topology. Compound 2 has 2D bilayer structure based on 2D [Zn(IPT)]_n single layer and mNBDC^2 − linkers. Compound 3 is a 3D pillar-layer framework built by Zn–CA bilayers and IPT⁻ pillars. The results showed that the coordination modes, configurations of IPT⁻, and the structure of carboxylate co-ligands have great influence on the structures of the final network. The choice of carboxylate can decide the result of CPs in Zn–IPT chains/net subunits plus carboxyl linkers or Zn–carboxylate chains/net subunits plus IPT⁻ linkers. The thermal stabilities and luminescent properties of selected compounds have also been studied.     

Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

Solvent-regulated assembly of 1-D and 2-D ZnII coordination polymers with tetrabromoterephthalate

Two distinct coordination polymers [Zn(TBTA)(DMF)₂(CH₃OH)₂]_n (1) and {[Zn(TBTA)_0.5(DMF)(OH)]-(H₂O)}_n (2) have been prepared from the vapor diffusion reactions of Zn^II nitrate with a rigid ligand tetrabromoterephthalic acid (H₂TBTA) under different solvent atmospheres. Both complexes have been characterized by elemental analysis, IR, powder X-ray diffraction, and TG-DTA techniques. Single crystal-X-ray diffraction studies reveal that 1 displays a 1-D linear motif with TBTA spacers whereas 2 presents a 2-D kgm network with the aid of hydroxyl spacers and 4-connected TBTA linkers.     

Observation of [Al(OH) n (H2O)6-n ] n (MoO4) in hydrotreating catalyst precursors by solid-state27 Al NMR

A previously unobserved octahedral²⁷Al MAS NMR resonance has been detected in rehydrated calcined Mo/Al₂O₃ hydrotreating catalyst precursors. This resonance is attributed to the presence of hydrated forms of aluminum molybdate such as [Al(OH) _n (H₂O)_6-n ] _n (MoO₄) (n = 1 or 2). The cross-polarization relaxation parameters, obtained from variable contact time experiments, yielded information on the relative sizes of the [Al(OH) _n (H₂O)_6-n ] _n (MoO₄) domains in the catalysts with different molybdenum loadings. Analysis of the²⁷A1 MAS NMR spectra of P-Mo(8)/Al₂O₃ and P-Mo(12)/Al₂O₃ (wt%P = 0.0–12.0) shows that a function of the phosphate in the 12 wt% Mo catalyst is to prevent the re-hydration of the molybdate phases on the calcined catalysts.     

Syntheses,structures and luminescence of zinc and cadmium coordination polymers with bis(1,2,4-triazol-1-yl)butane and benzenedicarboxylate

The self-assembly reactions of the flexible ligand 1,4-bis(1,2,4-triazol-1-yl)butane (btb) and rigid ligand 1,4-benzenedicarboxylate (bdc) with Zn(II) or Cd(II) give two novel coordination polymers {[Zn(bdc)(btb)](H₂O)₅}_n (1) and {[Cd₂(bdc)₂(btb)(H₂O)₂](H₂O)₇}_n (2). Coordination polymer 1, a supramolecular isomer of [Zn₂(bdc)₂(btb)₂](H₂O)₂ [X.L. Wang, C. Qin, E.B. Wang, Z.M. Su, Chem. Eur. J. 12 (2006) 2680], is a special 2D (6,3) network, with six Zn(II) atoms at six corners and four bdc and two double btb at six edges. Coordination polymer 2 exhibits a distorted 3D cubic topology that is built from dimer Cd₂ units. The blue luminescent emission maxima at 420 and 439 nm for 1, 440 and 455 nm for 2 were observed in the solid state at room temperature.     

Synthesis and characterization of the zinc(II) complex of a bleomycin analogue: a unique polymeric 2-[((2-(4-imidazoyl)ethyl)amino)carbony]-6-[((2-amino-2-methylpropyl)amino)methyl]pyridine zinc(II) nitrate complex

The reaction of 2-[((2-(4-imidazoyl)ethyl)amino)carbonyl]-6-[((2-amino-2-methylpropyl)amino)methyl]pyridine (L) with Zn^II(NO₃)₂·6H₂O has afforded a novel one-dimensional polymeric Zn^II complex, (Zn^II(L)(NO₃)₂)_n (2). Complex 2 crystallizes in the space group P2₁/n with a=8.955(3), b=13.216(3), c=18.941(3) Å, β=103.39(2)°, V=2180.6(10) ų, and Z=4. The geometry of each Zn^II is approximately a trigonal bipyramid: three nitrogens and one oxygen of the amide group are coordinated to the zinc while the fifth site is occupied by the imidazole nitrogen of a neighboring unit.     

Metal-organic frameworks constructed from monomeric,dimeric and trimeric phenanthroline citrate zinc building units

Adduct of mononuclear and dinuclear citrate zinc complex [Zn(Hcit)(phen)(H₂O)][Zn₂(Hcit)(phen)₂(H₂O)₃]·13.5H₂O (1) and its aggregate [Zn₃(Hcit)₂(phen)₄]_n·14nH₂O (2) (H₄cit = citric acid, phen = 1,10-phenanthroline) were synthesized in weak acidic solutions. The former was obtained from the reaction of zinc nitrate, citric acid and phenanthroline in a molar ratio of 3:2:3, while a slightly excess of phenanthroline results in the formation of the polymeric product 2 in a molar ratio of 3:2:4. Transformation of 1 to 2 was finished by the reaction of 1 with an equimolar of phenanthroline in 72% yield. Reverse conversion of 2 to 1 is obtained in 77% yield, showing an equilibrium between 1 and 2. Neutral compound 1 consists of one monomeric anionic unit [Zn(Hcit)(phen)(H₂O)]^? and one dimeric cationic unit [Zn₂(Hcit)(phen)₂(H₂O)₃]⁺ that connect each other by strong hydrogen bonds [O6?O4w 2.636(2); O7?O3w 2.630(3) Å]. In 2, the citrate ligand links each trinuclear unit [Zn₃(Hcit)₂(phen)₄] to generate an infinite 1D chain that extents into a 3D supramolecular structure by intra- and inter-molecular hydrogen bonds. Moreover, 1 and 2 exhibit strong fluorescence at room temperature.     

X-ray single-crystal structure and magnetic properties of KMn(H2O)5Ru2(CO3)4·5H2O: A layered soft magnet

The temperature manipulation induces the aggregation of Ru₂(CO₃)₄^3 − paddle-wheel precursors and Mn^2 + ions in lower temperature ~ 10 °C forming layer structural complex, K[Mn(H₂O)₄Ru₂(CO₃)₄]·5H₂O (1). It composes of new negative layer {Mn(H₂O)₅Ru₂(CO₃)₄}_nⁿ⁻, and magnetic exchanges between spin centers result in ordering below 3.8 K. The observed critical temperature is like the previously reported 3D hetero-metallic carbonates H_0.3K_0.7Mn[Ru₂(CO₃)₄](H₂O)_5.5, which demonstrates that it is independent of the interlayer connecting in such heterometallic complexes based on square-grid layer {Ru₂(CO₃)₄}_n³ⁿ⁻.     

Coordination assemblies of CdII/ZnII/CoII with the 3-(pyridin-4-yl) benzoate tecton: Structural diversity and properties

Three novel coordination polymers{[CdL₂(HL)(H₂O)]·(H₂O)}_n (1), [Zn₂(OH)L₃]_n (2) and [CoL₂(H₂O)]_n (3) have been hydrothermally synthesized from M(NO₃)₂·nH₂O (M^II = Cd^II, Zn^II and Co^II) and an unsymmetrical tecton 3-(pyridin-4-yl) benzoic acid (HL). All complexes show interesting structural patterns, namely, unprecedented 1D double-stranded supramolecular clasp for 1, novel (3,5,6)-connected helical tubular double layer for 2, 2-fold interpenetrating cds network for 3. The fluorescent and thermal properties of complexes 1, 2 and/or 3 have also been investigated.     

A novel two-dimensional network self-assembled by the narrowest ladder cations [Cu(CH3COO)(bpe)(H2O)]nn+ containing the Cu2(μ-O)2 cores and the dimeric anions [Cu2(nta)2(bpe)]2− through hydrogen-bonding interaction

A novel complex [Cu(CH₃COO)(bpe)(H₂O)]_n·n/2[Cu₂(nta)₂(bpe)] ·6nH₂O) (bpe=trans-1,2-bis(4-pyridyl)ethylene) was synthesized and characterized. The molecule structure shows that it is composed of the ladder-like double chain cations [Cu(CH₃COO)(bpe)(H₂O)]_nⁿ⁺ and the dimeric anions [Cu₂(nta)₂(bpe)]²⁻. Through bridging oxygen atom of the acetate, the Cu₂ (μ-O)₂ core is formed. The ladder-like chain cation is the narrowest ladder [3.422(3) Å]. Two-dimensional undulating network is constructed by the cations and the dimeric anions through hydrogen-bonding interactions.     

Synthesis and structure of the n = 4 member of the framework aluminium alkylenediphosphonate series Al2[O3PC n H2n PO3](H2O)2F2

We report here the solvothermal synthesis and crystal structure of the hybrid inorganic-organic framework material Al₂[O₃PC₄H₈PO₃](H₂O)₂F₂?2H₂O (monoclinic, 1P2₁ /m, a = 4.961(2) Å, b = 11.930(5) Å, c = 10.727(5) Å, β = 93.972(6)^°, Z = 2, R(F, F ² > 2σ) = 0.094, R _w(F ², all data) = 0.262), the third member of the Al₂[O₃PC _n H_{2 n} PO₃](H₂O)₂F₂ framework series. The structure is formed from corrugated chains of corner-sharing AlO₄F₂ octahedra in which alternating AlO₄F₂ octahedra contain two fluorine atoms in a trans or a cis configuration. The diphosphonate groups link the chains together through Al-O-P-O-Al bridges and through the butyl groups to form a three-dimensional framework structure containing a one-dimensional channel system consisting of one type of channel only. The channels contain four extra-framework water molecules per unit cell. The formation of this member of the series shows that the form of the alkyl chain can successfully define the number of channel types and the channel length in this hybrid framework system.     

Pillar-layered Zn–triazolate–carboxylate frameworks tuned by the bend angles of ditopic ligands

In the utilization of three ditopic ligands with different bend angles as pillars, we reported herein three pillar-layered Zn–triazolate–carboxylate frameworks, namely, [Zn₂(ATRZ)₂(BDC)]_n (1), [Zn₂(ATRZ)₂(TPDC)]_n·2nDMF (2) and [Zn₂(ATRZ)₂(ADDC)]_n (3) (ATRZ = 3-amino-1,2,4-triazole, H₂BDC = 1,4-benzenedicarboxylic acid, H₂TPDC = 2,5-thiophenedicarboxylic acid, and H₂ADDC = 1,3-adamantanedicarboxylic acid). Single crystal structural analyses demonstrate that different geometries of ditopic carboxylate pillars not only result in Zn–ATRZ layers adopting various corrugated configurations, but also give rise to 3,4-connected self-interpenetrated net of 1 and non-interpenetrated nets of 2 and 3. All these compounds exhibit high thermal stability and blue photoluminescence.     

A (3, 12)-connected coordination network based on rare tetragonal prism-like ZnII8 cluster

Hydrothermal reaction of zinc oxide, 1,2-benzenedicarboxylic acid (H₂pa) and 1,2,4-triazole (Htrz) yielded a (3,12)-connected 2-D coordination network [Zn₈(trz)₄(OH)₄(pa)₄]_n (1), in which rare tetragonal prism-like Zn^II₈ clusters and tridentate 1,2-benzenedicarboxylate act as 12- and 3-connected nodes, respectively. Moreover, the luminescent emission spectra and thermostability of 1 have been investigated.     

Hydrothermal Syntheses and Photoluminescent Properties of Two Zinc(II) Coordination Polymers Based on 4,6-di(1<Emphasis Type="Italic">H</Emphasis>-imidazol-1-yl)-1,3,5-triazin-2-ol

Two new Zn(II) coordination polymers based on the tridentate ligand 4,6-di(1H-imidazol-1-yl)-1,3,5-triazin-2-ol (Hdit), namely, {[Zn(dit)₂(H₂O)₂]·4H₂O}_n (1) and [Zn(dit)(CH₃COO)]_n (2), have been successfully constructed by varying the metal salts. Compound 1 shows 1D zigzag chain structure, and compound 2 is a 3D binodal (3,5)-connected architecture with {4²·6⁶·8²}{4²·6} topology. The photoluminescent spectra indicate that at room temperature, compounds 1 and 2 emit violet and blue luminescence, respectively.     

Hydrothermal synthesis of two new zinc coordination polymers with mixed ligands

The hydrothermal reactions of zinc acetate with 1,2,4,5-benzenetetracarboxylic anhydride (btc) and 4,4^′-bipyridine (4,4^′-bpy) for [Zn₂(4,4^′-bpy)(btc)(H₂O)₂]_n·2nH₂O (1) or imidazole (imi) for [Zn₂(imi)₄(btc)(H₂O)₂]_n (2) in the molar ratio of 1:1:1:2000 at 170 °C for five days led to the formation of colorless crystals of 1 and 2. The btc ligand acts as a four-dentate bridging ligand in both compounds to link up zinc atoms into linear chain architectures. In 1, the linear chain subpolymers are further interlinked into a lamellar framework via 4,4^′-bpy ligands. Finally, both 1 and 2 are extended into three-dimensional framework via hydrogen bonding.     

The novel polymeric potassium complex with a new coordination mode of orotic acid [K(μ5-H2Or)(μ-H2O)]n: Synthesis and structural characterization

Novel polynuclear seven-coordinated potassium complex, [K(μ₅-H₂Or)(μ-H₂O)]_n(H₃Or = orotic acid), with the new coordination mode of orotic acid has been prepared and characterized by elemental analysis, FT-IR spectra, X-ray diffraction. The orotate ligand exhibits new coordination mode of μ₅-κO, O: κO′, O′: O″ for H₂Or⁻.