Search

Three cadmium(II) coordination compounds, [Cd(pyip)2(CH3COO)2] (1), [Cd(pyip)2(cis-OH)2]·H2O (2) and [Cd(pyip)2(trans-OH)2]·3H2O (3), based on 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (pyip) have been synthesized by a hydrothermal method and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1, 2 and 3 all appear as monomeric entities, which are further assembled into supramolecular networks by hydrogen bonding interactions. The Cd(II) centers in compounds 2 and 3 lie in distinct octahedral environments with the hydroxyl groups in cis- and trans-positions, respectively, leading to the generation of different structures . Photoluminescence studies of compounds 1–3 were also carried out.

In order to effectively remove mercury from raw natural gas, a preparation method of columnar sulfur-impregnated activated petroleum coke was proposed and mercury adsorption experiments were conduc...

Although volatile arsenides in natural gas are usually in trace amounts, the service life of a catalyst in natural gas processing can still be shorten by them. Environmental pollution is caused by distribution of As into the atmosphere through gas burning. Health and safety issues happen for workers in close contact with unprocessed gas during exploration and handling. As an important part of natural gas product quality inspection, the technology of arsenic content detection in natural gas needs to break through immediately. We confirmed the feasibility of the two solutions as the adsorption of arsenic through choosing an arsenic adsorbent in natural gas and exploring multi-stage, circulating, and subsequent instrument methods. We selected concentrated nitric acid and silver nitrate solution as the adsorbents and tested the solutions by inductively coupled plasma mass spectrometry (ICP–MS). The results were obtained that the highest absorption efficiency of silver nitrate solution was 98.7%, the average o...

Solvothermal reactions of lanthanide chloride with a new ligand, H3L, 4′-(3-carboxylpyridyl)-2,2′:6′,2“-terpyridine-6,6”-dicarboxylic acid, yields seven new lanthanide–organic frameworks: {[Ln2L2]⋅H2O}n (Ln=Pr (1), Nd (2), Sm (3), Eu (4)), {[Ln5L4(COO)3(H2O)4]⋅10 H2O}n (Ln=Tb (5), Dy (6)), and [Yb2L2(H2O)2]⋅2 H2O (7). Single-crystal X-ray diffraction reveals that these complexes belong to three structural types. Type I (1–4) consists of lanthanide–carboxyl group layers pillared by L3− to form a three-dimensional network. Type II (5 and 6) comprises a right-handed helical chain and a left-handed helical chain linked through L3− anions into a three-dimensional framework. Type III (7) is a discrete dinuclear structure. The structural change is due to the decrease in the metal coordination number from nine for the large ions to seven for the small ions; this demonstrates the effect of lanthanide contraction. These materials exhibit high thermal stability. In addition, the luminescent properties of these complexes are discussed.

Two coordination polymers, [Mn2(btc)(phen)4]n·7nH2O (1) and [Co2(btc)(phen)(H2O)2]n·nH2O (2) (H4btc = biphenyl-3, 3′,4, 4′-tetracarboxylic acid, phen = 1, 10-phenanthroline) were hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compound 1 has a 1D chain structure in which the dinuclear Mn2 units are linked through (btc)4– ligands. Magnetic measurements revealed weak antiferromagnetic and ferromagnetic exchange coupling interactions between MnII and CoII ions in 1 and 2, respectively. Moreover, both compounds have good thermal stabilities.

Five structurally diverse complexes, [Cd 2 (pyip) 2 (suc) 2 ] n ·1.5 n H 2 O ( 1 ), [Zn(pyip)(glu)] n ( 2 ), [Cd(pyip)(glu)] n ( 3 ), [Zn(pyip) 2 (adip) 2 ] n ·2.5 n H 2 O ( 4 ), [Cd 3 (pyip) 2 (adip) 3 ] n ( 5 ) (pyip = 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenan-throline, H 2 suc = succinic acid, H 2 glu = glutaric acid, H 2 adip = adipic acid), have been hydrothermally synthesized. Complexes 1 and 4 are ribbon-like chains, in which pyip ligands attach to the both sides of the chain in pairs. Complex 2 is a one dimensional (1D) wave-like chain, while the pyip ligands attach to only one side of the chain. Complexes 3 and 5 are both two dimensional (2D) networks, in which the dicarboxylate ligands connect the dinuclear or trinuclear Cd II units into layers with (4, 4) topological network. The structural differences among these complexes show that the organic acids have important influences on the final structures.

Two novel cadmium(II) coordination polymers [Cd(pyip)(ox)]·H2O (1) and [Cd2(pyip)2(ox)2·(H2O)][Cd(pyip)(ox)]·4(H2O) (2) (pyip = 2-(pyridin-3-yl-1H-imidazo [4,5-f][1,10]phenanthroline, H2ox = oxalic acid), have been hydrothermal synthesized and characterized by single crystal X-ray diffraction. Compound 1 is 1D zigzag chain, in which oxalate anion as bridging ligand is responsible for the formation of the main framework and pyip as chelating ligand grafts on two sides of the zigzag chain. Compound 2 contains two kinds of independent polymers [Cd2(pyip)2(ox)2(H2O)] (A) and [Cd(pyip)(ox)] (B) to form an interdigitated 1D + 1D structure, in which polymers A and B are paratactically assembled in an ABCD sequence. The fundamental unit of polymer B in 2 is the same as that in 1. For compounds 1–2, weak interactions, primarily hydrogen bonding and π⋯π stacking interactions, have greatly influence on the supramolecular motifs recognized in the crystal packing. Especially, the oxalate anions as bridging ligand simultaneously adopt multiform coordination modes in two compounds. In addition, 1 and 2 displayed a strong fluorescent emission in the solid state at room temperature.

To determine the influence of metal ion and the auxiliary ligand on the formation of metal–organic frameworks, six new coordination polymers, {[Mn2(bpdc)(bpy)3(H2O)2] · 2ClO4 · H2O}n (1), {[Mn(bpdc)(dpe)] · CH3OH · 2H2O}n (2), {[Cu(bpdc)(H2O)2]}n (3), {[Zn(bpdc)(H2O)2]}n (4), {[Cd(bpdc)(H2O)3] · 2H2O}n (5), and {[Co(bpdc)(H2O)3] · 0.5dpe · H2O}n (6) (H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique MnII ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc2− ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.

Four new mixed-ligand complexes, namely [Zn2(pam)2(2,2′-bpy)2] (1), [Cd(pam)(2,2′-bpy)2]n (2), [Zn(pam)(phen)]n (3) and [Cd (pam)(phen)]n · 0.5n CH3CH2OH · 0.5nH2O (4) (H2pam = pamoic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydro(solvo)thermal conditions. Complex 1 possesses a discrete dinuclear metallamacrocyclic structure. Complex 2 is a 1D homochiral helical coordination polymer that is built from achiral components, whereas 3 displays a 1D helical chain structure. 4 is an unusual 2D double-layered structure generated by π ⋯ π interactions of two 2D networks. The structural differences of these complexes are mainly due to the differences of the size of the rigid aromatic chelate ligands and d10 metal ions. It appears that the chelate ligands and metal ions of the larger size favor the formation of high-dimensional structures, whereas those of the smaller size favor the formation of low-dimensional structures in the present system. The photoluminescence and thermal stability of these complexes were investigated.

Seven metal–organic coordination polymers, namely [Cd(sfdb)(phen)2]n·2nH2O (1), [Cd(sfdb)(bpy)2]n·nH2O (2), [Cu(sfdb)(phen)(H2O)]n·0.5nH2O (3), [Zn(sfdb)(bpy)(H2O)]n·0.5nCH3OH (4), [Cd(sfdb)(quin)]n (5), [Cd3(sfdb)2(Hsfdb)2(phen)2]n (6), and [Cd(sfdb)(bpy)]n (7) [H2sfdb = 4,4′-sulfonyldibenzoic acid, phen = 1,10-phenanthroline, quin = 2,2′-biquinoline, bpy = 2,2′-bipyridine] have been synthesized according to the principles of crystal engineering and structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction analyses. Compounds 1–3 form 1D zigzag chains. Two phen ligands chelate to one cadmium atom in 1, which is rare in similar polymers, while two 2,2′-bpy ligands coordinate one cadmium atom in 2. The zigzag chains in 3 propagate in two different directions (rotated by 75°) that are assembled by supramolecular forces into an intriguing three-dimensional network. Complexes 4 and 5 form square-wave-like 1D chains, although the results indicate a transformation of 2,2′-bpy into quin during the course of the hydrothermal synthesis of compound 5. Compound 6 is a 1D grid-chain based on a linear trinuclear unit, and compound 7 shows a 1D double chain containing 28-membered rings with sfdb2– ligands as bridges. Weak hydrogen bonding and intra- and/or intermolecular π···π stacking contacts in compounds 3–7 link the discrete 1D chains into high-dimensional supramolecular structures. The sfdb2– ligand displays multiple coordination modes in these seven complexes. Complexes 1, 2, and 4–7 show blue photoluminescence at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Four novel ZnII coordination polymers, [Zn(btc)0.5(H2O)]n (1), {[Zn(btc)0.5(4,4‘-bpy)0.5(H2O)]·1.5H2O}n (2), {[Zn2(H2btc)2(4,4‘-bpy)4]·H2O}n (3), [Zn(H2btc)(bpe)]n (4) [H4btc = biphenyl-3,3‘,4,4‘-tetracarboxylic acid, 4,4‘-bpy = 4,4‘-bipyridine, and bpe = 1,2-bis(4-pyridyl)ethane], have been synthesized by hydrothermal reactions. Single-crystal X-ray structural analysis reveals that the four polymers exhibit different novel bilayer architectures. Complex 1 possesses a bilayer structure in which two helical layers are further pillared by (btc)4- ligands into a two-dimensional (2D) bilayer network. Complex 2 is an unusual 2D double-layered supramolecular motif generated by hydrogen bonding interactions of two single-layered networks. Complex 3 displays a 2D supramolecular bilayer network formed by the one-dimensional {[Zn2(H2btc)2(4,4‘-bpy)4]·H2O}n polymer. Complex 4 features a 2D double-layered framework in which two puckering single layers are linked by μ2-carboxylato groups of (H2btc)2- anions. The diver...