Aromatic Polycarboxylic Acids Research Articles

Two new 3D cobalt(II) coordination polymers constructed by semi-rigid carboxylic acid ligand: Syntheses, structures and properties

Two novel coordination polymers, {[Co2(L)(H2O)5]·H2O}n (1), and {[Co5(L)2(H2O)6(μ3-OH)2]·2C3H7NO·2H2O}n (2) (H4L = 3, 3′, 5, 5′-diphenyl ether tetracarboxylic acid, C16H10O9) have been synthesized by assembling semi-rigid aromatic polycarboxylic acids with transition-metal cobalt salts, and structurally characterized by elemental analysis, thermogravimetric analysis, IR spectrum, powder X-ray diffraction, and single crystal X-ray diffraction analysis. Structural analysis showed both the L ligands in CP 1 and CP 2 were regarded as 4 connection points, while the binuclear clusters in CP 1 and the pentanuclear clusters in CP 2 were regarded as 4 connection points and 8 connection points, respectively. Finally, both CP 1 and CP 2 were 3D network structures connected by two nodes (4, 4-connected for CP 1 and 4, 8-connected for CP 2). In addition, temperature-dependent susceptibilities have been measured in the range of 2 to 300 K, indicating that both CP 1 and CP 2 have antiferromagnetic coupling between adjacent Co(II) ions. Finally, Electrochemical experiments show that the CP 1 and CP 2 have good electrochemical behaviors.

Evolution and chemical characteristics of organic aerosols during wintertime PM2.5 episodes in Shanghai, China: insights gained from online measurements of organic molecular markers

Abstract. Organic aerosol (OA) is a significant part of urban fine particulate matter (PM2.5), and a lack of detailed knowledge of their sources has increasingly hindered the improvement of air quality in China in recent years, as significant reductions have been achieved in inorganic ion constituents. In this study, a wide range of organic molecular markers in PM2.5 were monitored with a bi-hourly time resolution using a thermal desorption aerosol gas chromatograph system (TAG) in urban Shanghai in winter 2019. The molecular marker data have provided a unique source tracking ability in characterizing the evolution of organic aerosols during nine wintertime episodic events. Episodes primarily influenced by local air masses were characterized with higher proportions in PM2.5 and mass increments of both primary and secondary OA. Rapid increases in both the absolute mass concentration and relative proportion were observed for primary and secondary OA markers, indicative of vehicle emissions (e.g., alkanes, hopanes, and 2,3-dihydroxy-4-oxopentanoic acid) and cooking activities (e.g., saturated and unsaturated fatty acids and C9 acids). In comparison, episodes under significant influences of transported air mass were typically associated with a predominant PM2.5 contribution from secondary inorganic aerosols and enhanced OA contribution from biomass burning activities. The latter was evident from the tracer data (e.g., levoglucosan, aromatic polycarboxylic acids, and nitroaromatic compounds). Secondary OA markers associated with later-generation products of the hydrocarbon oxidation process, such as C3−5 dicarboxylic acids, were the most deficient during local episodes, while notably enhanced during the episodes under the influence of transported air masses, reflecting the different extent and pathways of atmospheric aging processing. The ability to distinguish the variations in the OA evolution during different types of episodes demonstrates the value of online organic molecular measurements for episodic analysis. The results indicate that control of local urban sources such as vehicular and cooking emissions would lessen severity of local episodes, while regional control of precursors for secondary inorganic aerosols and biomass burning activities would reduce PM2.5 episodes under synoptic conditions conducive for regional transport.

Supramolecular assemblies of polybenzimidazole and aromatic polycarboxylic acids with superior mechanical and H2/CO2 separation properties

Polybenzimidazole is doped with aromatic polycarboxylic acids to form supramolecular assemblies achieving strong size-sieving ability and thus high H2/CO2 selectivity.

Structural Diversities of a Series of Cd(II) Coordination Complexes Based on a Flexible Tripodal N-donor Ligand

Three Cd(II) coordination complexes with unique structures and topologies, namely, {[Cd(tttmb)(Hbtc)]·5H2O}n (1), {[Cd(tttmb)(m-phda)(H2O)]·2H2O}n (2), and {[Cd(tttmb)(o-cpla)]·(CH3CN)·(H2O)1.5}n (3), have been successfully synthesized under hydro(solvo)thermally condition based on a flexible tripodal N-contained ligand 1,3,5-tris(1,2,4-triazol-1-ylmethyl)-2,4,6-trimethylbenzene (tttmb) and aromatic polycarboxylate acids (H3btc = 1,2,4-benzenetricarboxylic acid, m-H2phda = 1,3-phenylenediacetic acid and o-H2cpla = Homophthalic acid). Complexes 1–3 were characterized by elemental analysis, IR spectroscopy, X-ray single-crystal diffraction and thermogravimetric analyses. 1 crystallize in the orthorhombic chiral space group P212121 and feature 3D coordination networks. 2 reveals a 2D ladder-like structure with (4,4) topology containing alternating Cd(II)/m-phda2− left- and right-handed helical motifs. 3 exhibits a 3D net with (63)(66)(7·82) topology. The structural and dimensional diversity of these complexes not only indicates that the flexible ligand tttmb exhibits strong coordination ability and diverse coordination modes, but also shows that aromatic polycarboxylates play important roles in constructing the frameworks of complexes. Moreover, the different photoluminescence behaviors of 1–3 have been studied in the solid state.

Wildfires: Identification of a new suite of aromatic polycarboxylic acids in ash and surface water

Ash and surface water samples collected after wildfires in four different geographical locations (California, Colorado, Kansas and Alberta) were analyzed. The ash samples were leached with deionized water, and leachates were concentrated by solid phase extraction and analyzed by liquid chromatography/time-of-flight mass spectrometry. In addition, three surface water samples and a lysimeter water sample were collected from watersheds recently affected by fire in California and Colorado, and analyzed in similar fashion. A suite of benzene polycarboxylic acids (BPCAs), with two and three carboxyl groups and their corresponding isomers were identified for the first time in both ash leachates and water samples. Also found was a pyridine carboxylic acid (PCA), 3,5-pyridine dicarboxylic acid. Furthermore, putative identifications were made for other carboxylated aromatic acids: quinolinic, naphthalenic, and benzofuranoic acid carboxylates. The wildfire ashes, a controlled wood ash, and post-fire surface water samples suggest that burned woody material, along with surface plant-material and heated o-horizon soil organic matter, contribute to both BPCAs and PCAs in runoff. This study is the first of its kind to identify this suite of aromatic acids in wildfire ash and surface water samples. These data make an important contribution to the nature of dissolved organic matter from wildfire and are useful to better understand the impact of wildfire on water quality and drinking water sources.

Two new copper(II) complexes based on 4-(1H-1,2,4-triazol-1-yl)phenol and different co-ligands: synthesis, crystal structures, luminescent properties and magnetic behavior

Two 4-(1H-1,2,4-triazol-1-yl)phenol (hptrz)-based transition metal complexes with different aromatic polycarboxylic acids as co-ligands, {[Cu2(H2O)4(hptrz)2(btec)]⋅2H2O}n (1) and [Cu(hptrz)2 (H2btc)2]·H2O (2) (H4btec = benzene-1,2,4,5-tetracarboxylic acid, H3btc = benzene-1,3,5-tricarboxylic acid), have been obtained, which were structurally characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectra, thermogravimetric curves and luminescence spectra in detail. Structural analysis reveals that 1 is a 1-D infinite chain framework extended by btec4– anions, whereas 2 is isolated centrosymmetric mononuclear entities. In contrast, the neutral hptrz is a terminal ligand to complete the metal coordination sphere and it also helps to assemble the low-dimensional coordination sphere into a high-dimensional supramolecular architecture by O–H···O hydrogen-bonding interactions. Additionally, the high stability and luminescence emission suggest that 1 and 2 are good candidates for light emission materials. The magnetic features of 1 may be due to weak antiferromagnetic coupling between CuII ions which are separated by btec4– anions.

A self-penetrated three-dimensional zinc(II) coordination framework based on 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid and 1,3-bis[(imidazol-1-yl)methyl]benzene ligands: synthesis, structure and properties.

With the rapid development of metal-organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen-containing ligands are employed to construct MOFs with fascinating structures. 4,4',4''-(1,3,5-Triazine-2,4,6-triyl)tribenzoic acid (H3TATB) and the bidentate nitrogen-containing ligand 1,3-bis[(imidazol-1-yl)methyl]benzene (bib) were selected to prepare a novel ZnII-MOF under solvothermal conditions, namely poly[[tris{μ-1,3-bis[(imidazol-1-yl)methyl]benzene}bis[μ3-4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn3(C24H12N3O6)2(C14H14N4)3]·2C3H7NO·3H2O}n (1). The structure of 1 was characterized by single-crystal X-ray diffraction, IR spectroscopy and powder X-ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single-crystal X-ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent ZnII centres, two 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoate (TATB3-) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each ZnII centre is four-coordinated and displays a distorted tetrahedral coordination geometry. The ZnII centres are connected by TATB3- anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link ZnII centres to give a helical Zn-bib-Zn chain. Furthermore, adjacent ladders are bridged by Zn-bib-Zn chains to form a fascinating three-dimensional self-penetrated framework with the short Schläfli symbol 65·7·813·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr4+ and Cu2+ ions.

Selective production and characterization of aromatic carboxylic acids from Xianfeng lignite-derived residue by mild oxidation in aqueous H2O2 solution

Lignites show great potential as feedstock for the production of valuable carboxylic acids by mild oxidation. In this study, valuable aromatic polycarboxylic acids were produced from Xianfeng lignite-derived residue (XLDR) through mild oxidation in green aqueous H2O2 solution. The results show that XLDR oxidation can produce benzene carboxylic acids (BCAs) and polycyclic aromatic carboxylic acids (PCACAs) in high selectivity. The BCAs are dominated by mellitic acid and benzenepentacarboxylic acid with 55.5% and 13.3% in the total yield of all group components based on the analysis with gas chromatography/mass spectrometer. Moreover, three series of PCACAs with an aliphatic ring were identified by direct analysis in a real-time ionization source coupled to a time-of-flight mass spectrometer. The BCAs and PCACAs could be generated from different kinds of aromatic structures via oxidation by OH produced from H2O2.

Chemical synthesis of polypyrrole film and its adsorption capacity for aromatic polycarboxylic acids

Polypyrrole (PPy) film was prepared via in-situ chemical polymerization of pyrrole monomer on the surface of red-clay-brick (RCB) substrate. The deposited PPy film was characterized and used as an adsorbent for removal of benzene polycarboxylic acids from aqueous solutions. The effects of solution pH, contact time, initial concentration, and temperature on the adsorption process were systematically investigated to find the optimum operating conditions. Adsorption kinetic data were best fitted by pseudo-second order kinetic model. The adsorption equilibrium data were most represented by the Freundlich isotherm model. The maximum adsorption amounts of Trimellitic, Hemimellitic, and Pyromellitic acids were 189.27, 177.26, and 203.31 mg/g, respectively. The thermodynamic studies indicate that the adsorption was an endothermic and spontaneous process. Also, the PPy-RCB film was successfully regenerated using sodium hydroxide solution. The regenerated PPy-RCB can be reused for more than four successive cycles with a low reduction in adsorption efficiency.

Series of Hydrated Heterometallic Uranyl-Cobalt(II) Coordination Polymers with Aromatic Polycarboxylate Ligands: Formation of U═O-Co Bonding upon Dehydration Process.

Five new heterometallic UO22+-Co2+ coordination polymers have been obtained by hydrothermal reactions of uranyl nitrate and metallic cobalt with aromatic polycarboxylic acids. Single-crystal X-ray diffraction reveals the formation of four 3D frameworks with the mellitate (noted mel) ligand and one 2D network with the isophthalate (noted iso) ligand. The compounds [(UO2(H2O))2Co(H2O)4(mel)]·4H2O (1), [UO2Co(H2O)4(H2mel)]·2H2O (2), and [(UO2(H2O))2Co(H2O)4(mel)] (4) consist of 3D frameworks built up from the connection of mellitate ligands and mononuclear metallic centers. These three compounds exhibit two types of geometry for the uranyl cation: pentagonal bipyramidal environment for 1 and 4, and hexagonal bipyramidal environment for 2. Using the mellitate ligand, the uranyl dinuclear unit is isolated in the compound [(UO2)2(OH)2(Co(H2O)4)2(mel)]·2H2O (3). Due to their 2D framework and the presence of uncoordinated cobalt(II) cations, the compound [(UO2)(iso)3][Co(H2O)6]·3(H2O) (5) is drastically different than the previous one. The thermal behavior of compounds 1, 2, and 3 has been studied by thermogravimetric analysis, X-ray thermodiffraction, and in situ infrared. By heating, the dehydration of compounds 1 and 2 promotes two structural transitions (1 → 1' and 2 → 2'). The crystal structures of [(UO2(H2O))2Co(H2O)2(mel)] (1') and [(UO2)Co(H2mel)] (2') were determined by single-crystal X-ray diffraction; each of them presents a heterometallic interaction between uranyl bond and the Co(II) center. Due to the rarely reported coordination environment for the cobalt center in compound 2' (square pyramidal configuration), the magnetic properties and EPR characterizations of the compounds 2 and 2' were also investigated.

Polyaniline films for efficient removal of aromatic acids from water

Adsorbents in the form of powders are commonly used to filtrate organic compounds in waters. However, this technique requires the separation of the solid phase from the solution after adsorption experiments. Here we propose the use of films as adsorbents. We synthesized polyaniline films by chemical oxidative polymerization of aniline on red ceramic brick. This film was tested to remove trimellitic, hemimellitic and pyromellitic acids as model molecules of the biodegradation of aquatic humic substances. We evaluated the effect of pH, contact time and initial concentration. Our results show that optimal adsorption conditions required 45 min of solid/liquid contact at pH 7 and an initial concentration of 20 mg/l. The maximum adsorption capacities for hemimellitic, trimellitic and pyromellitic acids are 154.83 for hemimellitic acid, 161.88 for trimellitic acid and 175.26 mg/g for pyromellitic acid. The adsorption efficiency of the polyaniline film decreased only by 13 % after four cycles. Overall, we conclude that polyaniline films are promising separable adsorbents compared to conventional adsorbents for removal of aromatic polycarboxylic acids from water.

Polycarboxylic acids in sea water: acid–base properties, solubilities, activity coefficients, and complex formation constants at different salinities

This paper reports the results of the investigations carried out in synthetic sea water at different salinities for different classes of polycarboxylic acids. The investigations can be summarized as follows: (a) Determination of the protonation constants in such multicomponent solution in a salinity range 15 ≤ S ≤ 45, at t = 25 °C, for the linear dicarboxylic acids HOOC-(CH2) n –COOH (0 ≤ n ≤ 8), and aromatic polycarboxylic acids (o-phthalic and 1,2,4-benzenetricarboxylic acids). For malonic, succinic, 1,2,3-benzenetricarboxylic, and 1,2,3,4-benzenetetracarboxylic acids, investigations were also carried out at t = 10 and 37 °C; (b) Determination of the total and intrinsic solubility (S T and S 0, respectively) of the linear dicarboxylic acids HOOC-(CH2) n -COOH (0 ≤ n ≤ 8), o-phthalic, 1,2,4-benzenetricarboxylic acids at t = 25 °C and 15 ≤ S ≤ 45, and calculation of the corresponding Setschenow parameters and activity coefficients; (c) Modeling the dependence of the experimental and literature protonation constants of the polycarboxylic acids on salinity, acid concentration, temperature, and number of the methylene groups in the molecules by means of new empirical equations; (d) Determination of the specific interaction parameters in synthetic sea water of the ionic species of the acids by means of the specific ion interaction theory and Pitzer models; (e) Determination of the protonation constant of the anion A1.117− of the single salt BA at different salinities and temperatures; (f) Determination and modeling in dependence of the salinity of the ΔH/kJ mol−1 of protonation of the linear dicarboxylic acids and of the A1.117− anion, by means of a Debye-Huckel type equation; (g) Determination of the complex formation constants (log β BpLHi) between the cation B1.117+ and the different deprotonated species of the carboxylic acids at different salinities and temperatures. Independent of the thermodynamic aqueous properties determined, a significant dependence of these parameters (log β i H , log β BpLHi, ΔH/kJ mol−1 of protonation, S T and S 0) on the ionic medium, salinity, and temperature was observed. Moreover, the huge number of data collected allowed us to propose some empirical equations to model/predict the behavior of these classes of O-donor ligands in a multicomponent solution such as synthetic sea water.

Supramolecular assemblies of 4,7-phenanthroline with various aromatic polycarboxylic acids

Five molecular complexes 1a–1e, of 4,7-phenanthroline (1) with various aromatic polycarboxylic acids such as benzene-1,3-dicarboxylic acid (a), pyridine-2,6-dicarboxylic acid (b), pyridine-2,5-dicarboxylic acid (c), benzene-1,2,3,4,5-pentacarboxylic acid (d) and 1,2,3,4,5,6-benzenehexacarboxylic acid (e) have been prepared and characterized by single crystal X-ray diffraction and thermogravimetric analyses. The analysis shows that all the assemblies crystallized as hydrates, except complex, 1c, formed between 1 and pyridine-2,5-dicarboxylic acid. Single crystal X-ray data reveals that the packing patterns of all the molecular complexes have been directed by strong hydrogen bonding O-H⋯O/O-H⋯N/N+-H⋯O− and weak hydrogen bonding C-H⋯O interactions. All the hydrated assemblies aggregate through the formation of cyclic networks as basic recognition pattern. Further, we observed that water molecules play significant role for production of supramolecular assemblies.

ChemInform Abstract: Research Progress of Metal‐Organic Frameworks Based on Aromatic Polycarboxylic Acid.

AbstractReview: [43 refs.

Research Progress of Metal‐Organic Frameworks Based on Aromatic Polycarboxylic Acid

AbstractMetal‐organic frameworks (MOFs) have attracted tremendous attention due to their fascinating structure types and extensive application prospect in many fields. In the process of synthesis, aromatic polycarboxylic acid as ligand plays an important role in constructing functional MOFs. In this review, we have summarized the research progress on the synthesis and structures analysis of MOFs based on aromatic polycarboxylic acids as well as their potential applications in magnetism, gas adsorption, separation, photodegradation, catalysis and emission.

Catalytic Actions of Sodium Salts in Direct Esterification of 3,3′4,4′-Benzophenone Tetracarboxylic Acid with Cellulose

Aromatic polycarboxylic acids can directly react with cellulose to form ester cross-linking structures and provide wrinkle resistance functions to cotton fabrics, different from aliphatic polycarboxylic acids, which will form anhydrides as intermediates. Sodium hypophosphite is a catalyst proven effective in the reactions of both acids. In order to find alternative catalysts, the mechanism of the direct esterification and the role of the catalyst in the reaction were investigated in this study. Several sodium salts of phosphorous acid and dichloroacetic acid with varied pKa values were employed in the treatment of cotton fabric with 3,3′,4,4′-benzophenone tetracarboxylic acid (BPTCA). The results confirmed that the overall reaction follows the Fischer esterification mechanism, an acid catalyzed reaction. The acid anions also play an important role in the reaction. Results of wrinkle recovery angles, FTIR band ratios of ester bonds, and thermogravimetric analyses of the treated fabrics consistently support...

Structural variation in silver(I) complexes with pyridazine ligand and aromatic polycarboxylic acids: Structural analysis with silver chains

To systematically explore the influence of pyridazine ligands and aromatic polycarboxylate on the existence of argentophilicity, four inorganic–organic hybrid Ag(I) complexes were obtained by one-pot ultrasonic reaction. Four complexes were named [Ag6(pdz)2(btc)2]n (1), [Ag2(pdz)(npt)]n (2), [Ag2(pdz)(pma)1/2]n (3), and [Ag2(pdz)(npa)·H2O]n (4) (pdz=pyridazine, H3btc=1,3,5-benzene tricarboxylic, H2npt=3-nitrophthalic acid, H4pma=pyromellitic acid, H2npa=1,4-naphthalenedicarboxylic acid). Structural analyses reveal that complexes 1–4 display diverse 2D or 3D frameworks, which all of the N-donor pdz ligands exhibit the same coordination mode but the distances of the silver atoms which link to the pdz ligands are different to each other. Complex 1 shows Ag6 clusters and the cluster is comprised by two distorted tetrahedron silver units. And the clusters are shared by two silver ions to form 1D silver chains. Complex 2 features 1D silver chains which are formed by the Ag4 units and the four Ag(I) ions are in the vertices of parallelogram. Complex 3 is an interpenetrating architecture with the pdz ligands alternately repeating up and down in ac plane. The structure of complex 4 is a 2D layer structure which the pdz and npt ligands alternately repeat along a axis. Moreover, complexes 1–4 indicate different photoluminescence behaviors in the solid state.

New coordination polymers with acylhydrazidate molecules as the linkers

By employing the hydrothermal in situ acylation of N2H4 with aromatic polycarboxylic acids, three new acylhydrazidate-extended coordination polymers (CPs) [Pb2(3-cppth)2(phen)2] (3-cppth=4-(3-carboxyphenoxy)phthalhydrazidate, phen=1,10-phenanthroline) 1, [Cd(4-cppth)(bpy)(H2O)]·H2O (4-cppth=4-(4-carboxyphenoxy)phthalhydrazidate, bpy=2,2′-bipyridine) 2 and [Zn(dcpth)2] (dcpth=4,5-dichlorophthalhydrazidate) 3 were obtained. X-ray single-crystal diffraction analysis revealed that (i) compound 1 possesses a one-dimensional (1-D) double-chain structure. Via the N–H⋯O interactions between the neighboring acylamino groups, two such double chains aggregate together into a 1-D supramolecular chain. The phen molecules are distributed on the outer side of the supramolecular chain, hindering the further extension of the 1-D supramolecular chain; (ii) compound 2 exhibits a 1-D zigzag-type single-chain structure. Via the hydrogen-bonded interactions between the acylamino groups, compound 2 self-assembles into a two-dimensional (2-D) grid-like supramolecular layer network. The π⋯π interactions between the bpy molecules are observed between the supramolecular layers; (iii) in compound 3, two hydroxylimino groups for the dcpth I molecules link first the Zn2+ ions into a dimer, which can be viewed as a tetrahedral node. The dcpth II molecules act as the linkers, extending the tetrahedral nodes into another 1-D double-chain structure, different from that of compound 1.

Construction of acylhydrazidate-extended metal-organic frameworks.

Under hydrothermal conditions, the reactions of Ba(2+)/Zn(2+), aromatic polycarboxylic acids and N2H4 with or without oxalic acid were carried out, affording four new acylhydrazidate-extended metal-organic frameworks (MOFs) [Ba(pmdh)] (pmdh = pyromellitdihydrazidate) 1, [Ba(sdpth)(H2O)2]·0.5H2O (sdpth = 4,4'-sulfoyldiphthalhydrazidate) 2, [Ba2(cpth)2(H2O)2] (cpth = 4-carboxylphthalhydrazidate) 3 and [Zn2(pdh)2(ox)]·H2O (ox = oxalate, pdh = pyridine-2,3-dicarboxylhydrazidate) 4. The acylhydrazidate molecules pmdh, sdpth, cpth and pdh in compounds 1-4 derived from the hydrothermal in situ acylation of N2H4 with aromatic polycarboxylic acids. X-ray single-crystal diffraction analysis revealed that (i) in compound 1, the pmdh I molecules link the Ba(2+) ions into a two-dimensional (2D) layer with a (4,4) topology, and then the pmdh II molecules extend these layers into a three-dimensional (3D) network; (ii) in compound 2, the sdpth molecules link the Ba(2+) ions to form a one-dimensional (1D) square tube. Interestingly, the tubes are further linked into a 3D supramolecular network via the N-H···O interactions, creating synchronously big channels; (iii) in compound 3, the cpth I molecules link the Ba1 ions into a 3D network with a (10,3) topology. Ba2 and cpth II are distributed on the channels; (iv) in compound 4, Zn(2+) and pdh aggregate to form two types of Zn4(pdh)4 clusters. The ox molecules act as the secondary linkers, extending the Zn4(pdh)4 secondary building units (SBUs) into a 3D network with a 6(6) topology. The photoluminescence analysis indicates that compounds 3 and 4 emit green light with maxima at 495 nm for 3 (λ(ex) = 397 nm), and 522 nm for 4 (λ(ex) = 395 nm), respectively. At 77 K, the activated 2 and 4 can adsorb N2 in amounts of 58.31 cm(3) g(-1) for 2 and 38.38 cm(3) g(-1) for 4, respectively.

Synthesis and Structure of Two Acentric Heterometallic Inorganic–Organic Hybrid Frameworks with Both Nonlinear Optical and Ferroelectric Properties

Solvothermal reactions of Cd(NO3)2·4H2O with aromatic polycarboxylic acids in the presence of sodium nitrate led to two acentric three-dimensional (3D) heterometallic inorganic–organic hybrid frameworks, namely, [Me2NH2][Cd2Na3(2,4-PYDC)4]·2H2O (1) and [Me2NH2] [CdNa(OH-m-BDC)2(H2O)2]·2H2O (2) (2,4-H2PYDC = 2,4-pyridinedicarboxylic acid, OH-m-H2BDC = 5-hydroxyisophthalic acid). The framework of 1 is constructed by a 3D inorganic Cd–Na connectivity, which resembles a concrete reinforcement structure and features a {CdNa}n rod-shaped chain, a {CdNa2}n helical chain, and a 20-membered {Cd6Na14} ring. Compound 2 is built up by one-dimensional inorganic {CdNa}n rod-shaped chains which are further connected by OH-m-BDC2– ligands, affording a 3D polymeric framework. Compounds 1 and 2 crystallize in acentric space groups, and both display powder second harmonic generation efficiencies approximately 0.8 and 0.7 times, respectively, than that of the potassium dihydrogen phosphate (KDP) powder. In addition, they also exhibit luminescence and potential ferroelectric properties.