Guest DMF Research Articles

Tuning of Second-Harmonic Generation in Zn-Based Metal–Organic Frameworks by Controlling the Structural Interpenetrations: A First-Principles Investigation

To explain the huge difference in the second harmonic generation (SHG) response of two novel interpenetrated metal–organic frameworks (MOFs) that consist of Zn2+ ions coordinated to the trans-2-(4-pyridyl)-4-vinylbenzoate (pvb) ligand, eightfold interpenetrated Zn(pvb)2 (M1) and sevenfold interpenetrated [Zn(pvb)2]·DMF (M2), first-principles calculations were performed to study the geometries, band structures, and various linear and second-order nonlinear optical properties of M1 and M2 and two other hypothetical Zn-MOFs. Our results indicate that the structural transformation from M2 to M1 by the loss of the DMF guest is energetically favorable, and the M1 compound with the most tightly packed structure has the largest dielectric constant. For MOFs with the same order of interpenetration, the presence of the DMF guest has a small effect on the optical anisotropy of the system. Due to the different coordination environments of two kinds of Zn atoms, eightfold interpenetrated M1 shows more significant optical anisotropy than M2, and correspondingly, the range of phase matchability of M1 (>863 nm) is wider than that of M2 (>1126 nm). This means that at an experimental wavelength of 950 nm, M1 has a favorable phase-matching feature and displays strong SHG response, while the phase-mismatched behavior of M2 with sevenfold interpenetration leads to a weak SHG signal. Therefore, the difference in the interpenetrated structure induced by the guest DMF solvent is the main reason for the giant deviation in SHG intensity between M1 and M2 compounds. The present work provides new insights into how the phase-matching ability can be tuned by switching of the degree of interpenetration to enhance SHG response of MOFs.

Synthesis, structure and luminescent properties of Zn(II) metal–organic frameworks constructed by flexible and rigid ligands

The synthesis of new coordination polymers based on flexible ligands is a challenging task. The use of two types of ligands is a possible approach to obtain crystalline compounds. The combination of flexibility and rigidity can lead to unusual topologies and properties. We are managed to obtain two new metal–organic frameworks (MOFs) based on flexible 1,3-bis(2-methylimidazolyl)propane and rigid isophtalic (1,3-benzenedicarboxylic) acid: [Zn2(iph)2(bmip)2] (1) and [Zn4(iph)4(bmip)3]·2DMF·3.5H2O (2). Structure of both compounds were determined by single-crystal X-ray analysis. Compound 1 is 3-fold interpenetrating 3D framework with dmp topology. Compound 2 is 2-fold interconnecting 3D framework with rare topology, described as (4,6)-c net. Compound 2 contains guest DMF and water molecules. Interestingly, compound 2 easily loses guest molecules in air and undergoes to another crystalline compound 2a. The photoluminescence at room temperature of the compounds 1 and 2a were investigated in the solid state. Quantum yields (QY) of luminescence for 1 and 2a are 30.5% and 39.8%, respectively. The short decay times are allowed to attribute the emission to fluorescence characteristic for intraligand transitions.

Zn(II) and Co(II) 3D Coordination Polymers Based on 2-Iodoterephtalic Acid and 1,2-bis(4-pyridyl)ethane: Structures and Sorption Properties.

Metal-organic frameworks [M2(2-I-bdc)2bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.

Zinc(II)-Organic Framework Films with Thermochromic and Solvatochromic Applications.

Multiple-stimuli-responsive photoluminescence films based on a ZnII -organic framework, {[Zn2 (Htpim)(3,4-pydc)2 ]⋅4 DMF⋅4 H2 O}n (1, Htpim=2,4,5-tri(4-pyridyl)imidazole, 3,4-H2 pydc=3,4-pyridinedicarboxylic acid), were fabricated. This compound consisted of a 2D corrugated layer, {Zn(3,4-pydc)}n , which was further pillared using a Y-shaped pillar N-donor ligand (Htpim) to form a 3D-pillared-layer framework with 1D open channels. The rectangular channels in the as-synthesized compound are fully occupied by guest DMF and H2 O molecules. The framework exhibits instant and reversible thermochromic properties corresponding to the removal of different H2 O and DMF guest molecules as temperature increases. The pale-yellow crystal undergoes significant redshifting to a greenish emission centered at 530 nm. Compound 1 also showed remarkable solvatochromic effects in the presence of various organic solvents without affecting its structural integrity. In addition, polycrystalline MOF films were grown on an α-Al2 O3 support for switchable and fast-response thermochromic and solvatochromic sensors.

Design and Construction of a Chiral Cd(II)-MOF from Achiral Precursors: Synthesis, Crystal Structure and Catalytic Activity toward C-C and C-N Bond Forming Reactions.

Using achiral components, a V-shaped dicarboxylic acid (H2L) and a conformationally flexible bidentate linker (bpp), a thermally stable chiral metal organic framework {[Cd(bpp)(L)(H2O)]·DMF} n (1), where H2L = 4,4'-(dimethylsilanediyl)bis-benzoic acid, bpp = 1,3-bis(4-pyridyl)propane and DMF = N,N-dimethylformamide, has been solvothermally synthesized and crystallographically characterized. It consists of 1D helical chains linked at the cadmium centers resulting in an overall 2D framework. Its microporous nature was confirmed by gas-sorption measurements. Upon thermal activation of 1, where both guest DMF molecules present in the 1D open channels and the coordinated H2O molecules are removed, its active metal site shows Lewis acid character to be an excellent heterogeneous catalyst for the C-C (Knoevenagel condensation reaction) and C-N (Strecker) bond forming reactions.

Polycatenated 2D Hydrogen-Bonded Binary Supramolecular Organic Frameworks (SOFs) with Enhanced Gas Adsorption and Selectivity.

Controlled assembly of two-dimensional (2D) supramolecular organic frameworks (SOFs) has been demonstrated through a binary strategy in which 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)pyridyl)naphthalene (2), generated in situ by oxidative dehydrogenation of 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)dihydropyridyl)naphthalene (1), is coupled in a 1:1 ratio with terphenyl-3,3′,4,4′-tetracarboxylic acid (3; to form SOF-8), 5,5′-(anthracene-9,10-diyl)diisophthalic acid (4; to form SOF-9), or 5,5′-bis-(azanediyl)-oxalyl-diisophthalic acid (5; to form SOF-10). Complementary O–H···N hydrogen bonds assemble 2D 63-hcb (honeycomb) subunits that pack as layers in SOF-8 to give a three-dimensional (3D) supramolecular network with parallel channels hosting guest DMF (DMF = N,N′-dimethylformamide) molecules. SOF-9 and SOF-10 feature supramolecular networks of 2D → 3D inclined polycatenation of similar hcb layers as those in SOF-8. Although SOF-8 suffers framework collapse upon guest removal, the polycatenated frameworks of SOF-9 and SOF-10 exhibit excellent chemical and thermal stability, solvent/moisture durability, and permanent porosity. Moreover, their corresponding desolvated (activated) samples SOF-9a and SOF-10a display enhanced adsorption and selectivity for CO2 over N2 and CH4. The structures of these activated compounds are well described by quantum chemistry calculations, which have allowed us to determine their mechanical properties, as well as identify their soft deformation modes and a large number of low-energy vibration modes. These results not only demonstrate an effective synthetic platform for porous organic molecular materials stabilized solely by primary hydrogen bonds but also suggest a viable means to build robust SOF materials with enhanced gas uptake capacity and selectivity.

Synergistic host-guest hydrophobic and hydrogen bonding interactions in the complexation between endo-functionalized molecular tube and strongly hydrophilic guest molecules in aqueous solution.

The propensity of complex formation of a host, an endo-functionalized naphthotube that has bisnaphthalene cleft architecture (host-1b), with four different strongly neutral hydrophilic guest molecules, namely 1,4-dioxane (14D), acetone, DMSO and DMF, in water is examined using classical molecular dynamics simulations. This type of molecular tube has received significant attention recently due to its usefulness as a supramolecular catalyst and for its ability to selectively recognise biologically and environmentally important neutral molecules in aqueous solution. We sequentially address the role of the different guest molecules in the structural change of host-1b, the role of the host-inserted guest and the water-inserted guest hydrogen bond properties and the host-guest binding free energies in the complex. The derivatives of our findings are: (a) the host changes its shape upon the insertion of a guest molecule and the magnitude of the shape change depends on the type and the nature of the guest molecule; (b) the complete insertion of a guest into the cavity of host-1b is only observed for guest 14D; and (c) the complete removal of water molecules from the host cavity is observed for guest 14D and the presence of a single water molecule is observed for all other guest molecules. The PMF and MM-PBSA calculations reveal that host-1b/14D complexation is the most energetically stable and the synergistic host-guest hydrophobic and hydrogen bonding interactions play a profound role in the stability of these host-guest complexes. Specifically, as the host cavity contains a small hydrophilic part and a large hydrophobic part, guest molecules with both these parts can form hydrogen bonds with the hydrophilic part of the host as well as forming a favorable hydrophobic interaction with the hydrophobic part of the host at the time of complexation.

Modification of Network and Pore Dimensionality in Metal–Organic Frameworks Containing a Secondary Phosphine Functionality

Three new metal–organic frameworks containing a triphenylphosphine moiety, namely, [Zn3(tpp)2(DMF)2]·nDMF (1), [Zn3(tpp)2(4,4′-bpy)2]·nDMF (2), and [Zn3(tpp)2(3,3′-bpy)]·nDMF (3), were synthesized using 4,4′,4″-phosphanetriyltribenzoic acid (H3tpp) as a tritopic linker. The absence or presence of additional N-donor linker molecules in the reaction mixture lead to the formation of (3,6)-c layered, (3,8)-c pillared layered, or (3,4,6)-c frameworks. Compound 1 is composed of a trinuclear zinc secondary building unit (SBU) and the tpp3– anion arranged in a layered (3,6)-c network with kgd topology. There are DMF guest molecules coordinated to the terminal Zn atoms of the trinuclear inorganic SBU. The addition of the neutral N-donor molecules 3,3′-bipyridine (3,3′-bpy) and 4,4′-bipyridine (4,4′-bpy) as second organic linker molecule lead to an increase of dimensionality of the networks. Compound 2 is a (3,4,6)-nodal three-dimensional MOF. Its structure consists of two equivalent interpenetrated nets with the point symbol (52·64)(52·6)2(54·66·72·8·92) containing solvent filled pockets. The free electron pair of the phosphorus atom of the triphenylphosphine moiety is pointing toward the zero-dimensional pores. The structure of 3 can be described as layers of 1 which are connected by 3,3′-bipyridine as pillar into a three-dimensional (3,8)-c network with the point symbol (43)2(46·618·84). The non-interpenetrated structure of 3 contains a solvent filled three-dimensional pore system. All three materials exhibit uptake of CO2 at 195 K after removal of the guest DMF molecules. This is particularly surprising for 2, with its zero-dimensional pores in the single-crystal structure and absence of N2 adsorption at 77 K. Compound 3 shows a large gate opening effect for CO2 adsorption at 195 K.

Synthesis, crystal structure and magnetic properties of a dinuclear dysprosium single-molecule magnet

To seek novel dysprosium based single-molecule magnets, a dinuclear dysprosium complex, namely [Dy2(L)2(DBM)2(DMF)2]·2DMF (1) was successfully obtained by employing tridentate Schiff base ligand (where H2L=2-hydroxy-N′’-(2-hydroxy-3-methoxybenzylidene) benzohydrazide), HDBM=dibenzoylmethane, DMF=dimethylformamide). Single-crystal X-ray structural analysis reveals that the key feature of 1 is neutral dinuclear complex, in which two Dy(III) ions with eight-coordinated environment are bridged by two phenoxido oxygen atoms from two Schiff base ligands. Interestingly, complex 1 could be regarded as the structurally related derivatives to our previous reported complex of [Dy2(L)2(DBM)2(DMF)2] (1a) but adding two guest DMF solvents. More importantly, the energy barrier to magnetic relaxation of 1 is slightly higher, with a value of 33K, when compared to the corresponding complex 1a of 24K, which provides a good example towards regulating magnetization dynamics in dinuclear dysprosium (III) single-molecule magnets by guest solvent molecules.

Two Zinc(II) metal-organic frameworks with mixed ligands of 5-amino-tetrazolate and l,2,4,5-benzenetetracarboxylate: Synthesis, structural diversity and photoluminescent properties

The reactions of Zn(NO3)2·6H2O with mixed ligands of 5-amino-tetrazole (Hatz) and l,2,4,5-benzenetetracarboxylic acid (H4btec) under hydro(solvo)thermal conditions, gave two three-dimensional (3D) porous metal-organic frameworks (MOFs) of {[Zn3(atz)2(btec)(DMF)2]·DMF·2H2O}n (1) and [Zn2(Hprz)(atz)(btec)(H2O)]n (2) in the absence and presence of piperazine (prz), respectively. 1 and 2 were characterized by infrared spectra (IR), elemental analyses (EA) and single-crystal/powder X-ray diffraction. In 1, the adjacent 1D [Zn3(btec)]n2n+ chains are linked together by atz− ligands to form a 3D porous MOF with 1D tetragonal channels filled with coordinated and guest DMF, and lattice water molecules. In 2, the adjacent 2D [Zn2(btec)]n wavelike sheets are pillared through atz− ligands to generate a 3D layered-pillared porous MOF with 1D open channels, which are occupied by coordinated Hprz+ cations and coordinated water molecules. Additionally, thermal stabilities and photoluminescent properties of both compounds in the solid-state at room temperature have been investigated and discussed in detail.

Field-Induced Slow Magnetic Relaxation and Gas Adsorption Properties of a Bifunctional Cobalt(II) Compound.

A new compound, {[Co(bmzbc)2] · 2DMF}n (JXNU-1, JXNU denotes Jiangxi Normal University), based on the 4-(benzimidazole-1-yl)benzoate (bmzbc(-)) ligand has been synthesized and structurally characterized. The Co(II) ions are bridged by the rod-like bmzbc(-) ligands to give a two-dimensional (2D) sheet wherein the Co(II) ions are spatially separated from each other by the long bmzbc(-) rods. The 2D sheets are further stacked into a 3D framework with 1D channels occluding the guest DMF molecules. Detailed magnetic studies show that the individual octahedral Co(II) ions in JXNU-1 exhibit field-induced slow magnetic relaxation, which is characteristic behavior of single-ion magnets (SIMs). The rarely observed positive value of zero-field splitting (ZFS) parameter D for the Co(II) ion in JXNU-1 demonstrates that JXNU-1 is a unique example of Co(II)-based SIMs with easy-plane anisotropy, which is also confirmed by the calculations. The microporous nature of JXNU-1 was established by measuring CO2 sorption isotherms. The abrupt changes observed in the C3H8 and C2H6 adsorption isotherms indicate that a structural transformation occurred in the gas-loading process. The long connection between the magnetic metal centers in JXNU-1 meets the requirements for construction of porosity and SIM in a well-defined network, harmoniously providing a good candidate of functional molecular materials exhibiting SIM and porosity.

How the guest molecules in nanoporous Zn(II) metal-organic framework can prevent agglomeration of ZnO nanoparticles

The host and the apohost framework of [Zn2(BDC)2(H2O)2·(DMF)2]n (1·2H2O·2DMF), (BDC2−=benzene-1,4-dicarboxylate and DMF=N,N-Dimethylformamide), were synthesized and subsequently used for preparation of ZnO nanomaterials. With calcination of the host framework of 1·2H2O·2DMF, ZnO nanoparticles were obtained. By the same process on the apohost framework of 1, agglomerated nanoparticles of ZnO were formed. These nano-structures were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). These results indicate that with removal of the guest DMF and coordinated H2O molecules from the one-dimensional channels of 1·2H2O·2DMF, the tendency of nanoparticles to agglomerate increases and the role of this MOF in preparation of ZnO nanoparticles from this precursor was reduced.

Supramolecular assembly of a series of new coordination polymers based on 4,4′-(carbonylimino)dibenzoic acid: Syntheses, structures and photoluminescence investigation

Assembly reactions of acylamide-containing dicarboxylate ligand 4,4′-(carbonylimino)dibenzoic acid (H2L) with corresponding divalent metal ions resulted in the formation of seven new coordination polymers, namely Cd(L)(H2O) (1), Zn(L)(H2O) (2), Zn5(L)2(OH)6 (3), [Ni(L)(H2O)2]·H2O (4), [Cd(L)(py)(H2O)]·(DMF)·(C6H5Cl) (5), [Cd(L)(py)2]·2CH3OH (6) and [Mn (HL)2(py)2]·2DMF (7). In complex 1, the double chains composed CdII and L2− are connected by interlayer Cd–O bonds to form a three-dimensional architecture. Complex 2 exhibits a three-dimensional supramolecular architecture extended by hydrogen bonds involving O–H⋯O and N–H⋯O types. Complex 3 displays a three-dimensional framework consisting of zinc-hydroxide layers and L2− pillars. Complex 4 is also a supramolecular three-dimensional network generated from linkage of Ni–O chains via versatile hydrogen bonds. Complex 5 exhibits an interdigitated network in which the cavities are occupied by guest DMF and C6H5Cl molecules. In complex 6, two-dimensional square-grid network was generated by linkage of Cd2 units with L2− ligands. Mono-depronated ligand presents in complex 7. The adjacent [Mn(py)(HL)] chains are arranged parallel to each other by forming hydrogen bonding between the acylamide groups and guest DMF molecules. The stability properties of 2, 3, 4, 6 and 7 have been presented. In addition, photoluminescence properties of complexes 2, 3, 5 and 6 are investigated.

Different dimensionality in Mn(II), Co(II) and Ni(II) aminoisophthalate metal–organic compounds: Synthesis, characterization and gas adsorption properties

Five new 5-aminoisophthalic acid (H2aip) complexes with Mn(II), Co(II) and Ni(II) ions, {[Mn2(μ3-aip)2(bipy)2]·2DMF·2H2O}n (1), [Co(pmi)(H2O)4]·2H2O (2), {[Ni(μ-aip)(H2O)2(en)]·3H2O}n (3), [Ni(μ3-aip)(im)(H2O)2]n (4) and [Ni(aip)(phen)(H2O)3]·2H2O (5) (H2aip=5-aminoisophthalic acid, bipy=2,2′-bipyridine, pmi=5-(pyridin-2-ylmethylamino)isophthalate, en=ethylenediamine, im=imidazole, phen=1,10-phenanthroline) were synthesized at room temperature. The compounds were characterized by elemental analysis, magnetic and spectroscopic measurements (UV–Vis and FT-IR), single crystal X-ray diffraction techniques and thermal analysis (TG, DTG and DTA). Furthermore, in order to assess the potentials of the complexes in gas storage applications, we performed atomically detailed simulations. The single crystal X-ray diffraction study of 1 reveals a 2D coordination polymer. The 2D layers are extended into a 3D supramolecular network with 1D channel via interlayer π⋯π stacking interactions between bipy ligands. The voids of the channels are filled with guest water and DMF molecules. Schiff base complex 2 has been obtained from H2aip, pyridine-2-carboxaldehyde and CoCl2·6H2O in a one-pot reaction. Compound 2 is a discrete mononuclear complex which crystallizes in the space group P21/c. Complex 3 is a 1D coordination polymer and the Ni(II) ion is six-coordinated in a distorted octahedral geometry. In 3, aip exhibits a new coordination mode as a bis(monodentate) bridging ligand. Complexes 2 and 3 show 2D and 1D metal–water clusters between metal ions and water molecules, respectively. Complex 4 reveals a 2D coordination polymer that crystallizes in the space group P21/c. Adjacent 2D layers are further extended into a 3D supramolecular network by hydrogen bonds and π⋯π interactions. The crystal analysis of 5 reveals that it is a mononuclear complex and the Ni(II) ion exhibits a distorted octahedral geometry.

Vanadium Analogues of Nonfunctionalized and Amino‐Functionalized MOFs with MIL‐101 Topology – Synthesis, Characterization, and Gas Sorption Properties

AbstractSyntheses, characterization, and gas sorption properties of two new vanadium‐based metal–organic frameworks [V3OCl(DMF)2(BDC)3]·3.1DMF·10H2O·0.1BDC (V–MIL‐101 or 1) and [V3OCl(DMF)2(BDC–NH2)3]·2.8DMF·H2O·0.1BDC–NH2 (V–MIL‐101–NH2 or 2) (DMF = N,N′‐dimethylformamide; BDC = terephthalate; BDC–NH2 = 2‐aminoterephthalate) having MIL‐101 topology are presented. Compounds 1 and 2 were prepared under similar solvothermal conditions (150 °C, 24 h) in DMF by using VCl3 and H2BDC or H2BDC–NH2, respectively. Determination of lattice parameters from X‐ray powder diffraction (XRPD) patterns of thermally activated compounds revealed their structural similarity with chromium‐, iron‐, and aluminum‐based solids having two types of mesoporous cages and accessible metal sites. The phase purity of the compounds was ascertained by XRPD analysis, diffuse reflectance Fourier transform (DRIFT) spectroscopy, and elemental analysis. Thermogravimetric analyses (TGA) and temperature‐dependent XRPD (TDXRPD) experiments indicate that the compounds are stable up to 320 and 240 °C, respectively, under an argon atmosphere. Removal of the guest DMF molecules by thermal activation enables the compounds to adsorb significant amounts of N2 (690 and 555 cm3 g–1 at p/p0 = 1 for 1 and 2, respectively) and CO2 (9.0 and 4.3 mmol g–1 at 24.5 and 22.8 bar for 1 and 2, respectively).

A new microporous Cu(II)-isonicotinate framework with 8-connected bcu topology

Abstract A new microporous Cu(II)-isonicotinate framework Cu(int)2·DMF(1, int = isonicotinate; DMF = N,N-dimethylformamide) with large open channels filled by guest DMF molecules has been solvothermally synthesized and structurally characterized. It features a typical bcu topology by reducing the dinuclear Cu units as the 8-connected nodes. Such bcu-type framework is much stable after removal of the guest DMF molecules and shows notable CO2 sorption behavior.

Guest exchange dynamics in a flexible bilayer porous coordination polymer

A novel Cd(II)-organic framework [Cd(bpdc)(bpy)⋅DMF] (1) (H2bpdc = biphenyl-3,4′-dicarboxylic acid, bpy = 4,4′-bipyridine) has been synthesized by the solvothermal reaction of Cd2 + salt with H2bpdc and bpy in N,N-Dimethylformamide (DMF) solvent. Single crystal X-ray diffraction revealed that 1 has a two-dimensional (2D) bilayer structure, and the bilayers of 1 are further mutually interdigitated to form a 3D microporous framework. Guest exchange experiments for 1 with several organic solvents and water were performed, and the results display that ethanol can exchange with the guest DMF molecules in 1, but methanol, acetonitrile and water solvents can only induce 1 to extract its guest DMF molecules. Powder X-ray diffraction shows that 1 undergoes a small framework slip between the adjacent interdigitated bilayers triggered by the guest exchange, and the original framework can be restored after the exchanged samples soaked back in the DMF solvent, which demonstrated that 1 has dynamic and flexible interdigitated bilayer motif. The photoluminescent characterization shows that 1 displays blue-green emission in the solid state at room temperature.

A series of three-dimensional lanthanide(iii) coordination polymers of 2,5-dihydroxy-1,4-benzenedicarboxylic acid based on dinuclear lanthanide units

The reactions of Ln(NO3)3 with 2,5-dihydroxy-1,4-benzenedicarboxylic acid (H2-DHBDC) under solvothermal conditions produce a series of isomorphous lanthanide coordination polymers with the empirical formula {[Ln2(DHBDC)3(DMF)4](DMF)2}n (Ln = La(1), Nd(2), Sm(3), Gd(4), and Er(5)). Compound {[Ln2(DHBDC)3(DMF)4](DMF)2}n contains dinuclear Ln2(COO)6 units, which are linked by the –C6H2(OH)2– spacers to form a three-dimensional framework exhibiting α-Po topology (pcu-(412·63) net) based on dinuclear Ln2(COO)6 nodes. The three-dimensional framework shows one-dimensional open channels that accommodate the coordinated and guest DMF molecules. Gas adsorption measurements on compound 4 indicate that the desolvated solid of 4 adsorbs CO2 and shows nonporous behavior toward N2. The adsorption favoring CO2 over N2 may arise from the chemical environments of the host framework, which contains the polar –OH groups of the phenyl and the π-electrons of the ligands. Magnetic measurements on compound 4 indicate that there is an antiferromagnetic interaction between Gd3+ ions.

Multifunctional Homochiral Lanthanide Camphorates with Mixed Achiral Terephthalate Ligands

Seven homochiral lanthanide camphorates with mixed achiral terephthalate ligands, namely, {Ln(2)(cam)(2)(bdc)(H(2)O)(2)}·DMF [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7); d-H(2)cam = d-(+)-camphoric acid; H(2)bdc = 1,4-benzenedicarboxylic acid; DMF = N,N'-dimethylformamide], have been solvothermally synthesized. Single-crystal X-ray diffraction analyses reveal that compounds 1-7 are isostructural and crystallize in orthorhombic, chiral space group P2(1)2(1)2(1). These structures feature three-dimensional open frameworks based on rodlike [Ln(2)(OCO)(6)(H(2)O)(2)](n) secondary building units, with the guest DMF molecules occupying the void space of the host {Ln(2)(cam)(3)(bdc)(H(2)O)(2)} framework. The photophysical and magnetic properties of some of these complexes have been investigated. Notably, the terbium compound 4 is highly emissive with a quantum yield of 63.68%. Additionally, thermogravimetric analyses, variable-temperature IR spectroscopy, and powder X-ray diffraction of 2 as a representative were performed to determine its thermal stability, which indicates that the framework still remains intact until 300 °C.

Anionic Metal–Organic Frameworks of Bismuth Benzenedicarboxylates: Synthesis, Structure and Ligand‐Sensitized Photoluminescence

AbstractFour organic–inorganic bismuth benzenedicarboxylate (bdc)frameworks, [Bi(1,4‐bdc)2(dmf)]·(dma)(dmf)2 (1), [Bi(1,4‐bdc)2]·(dma)(dmf) (2), [Bi4(1,4‐bdc)7(HIm)]·(dma)2(dmf)2 (3) and [Bi(1,4‐bdc)2]·(dma) (4) (where dma = dimethyl ammonium cation, HIm = imidazole and dmf = dimethylformamide) have been synthesized under solvothermal conditions, and their structures were determined by single‐crystal X‐ray diffraction. Compound 1 has a layer structure, whereas compounds 2–4 have three‐dimensional structures. All four frameworks are anionic and contain dma cations within cavities in their structures. Compounds 1–3 also contain coordinated and/or guest dmf molecules. The topologies of compounds 1–3 have 4‐connecting nodes; the layer structure in 1 is a corrugated (4,4)‐connected square lattice, but the three‐dimensional structures of 2 and 3 adopt the (dia) net topology. Compound 4 has a 6‐connecting node with a (pcu) net topology. The BiOn polyhedra are hemidirected with a stereochemically active lone pair of electrons in 2, but holodirected with astereochemically inactive lone pair of electrons in 1, 3 and 4. Tb3+‐ and Eu3+‐doped and co‐doped 3 and 4 emit intense, ligand‐sensitized green, red or orange luminescence, respectively.