Substituent dependent dimensionalities in cobalt isophthalate supramolecular complexes and coordination polymers containing dipyridylamine ligands

Hydrothermal synthesis has afforded cobalt 5-substituted isophthalate complexes with 4,4′-dipyridylamine (dpa) ligands, showing different dimensionalities depending on the steric bulk and hydrogen-bonding facility of the substituent. [Co(tBuip)(dpa)(H₂O)]_n (1, tBuip = 5-tert-butylisophthalate) is a (4,4) grid two-dimensional coordination polymer featuring 2-fold parallel interpenetration. [Co(MeOip)₂(Hdpa)₂] (2, MeOip = 5-methoxyisophthalate) is organized into 3-fold parallel interpenetrated (4,4) grids through strong N-H⁺?O⁻ hydrogen bonding. {([Co(OHip)(dpa)(H₂O)₃])₃·2H₂O}_n (3, OHip = 5-hydroxyisophthalate) possesses 1-D chain motifs. The 5-methyl derivative {[Co(mip)(dpa)]·3H₂O}_n (4, mip = 5-methylisophthalate) has a 3-D 6⁵8 cds topology. {[Co(H₂O)₄(Hdpa)₂](nip)₂·2H₂O} (5, nip = 5-nitroisophthalate) and {[Co(sip)(Hdpa)(H₂O)₄]·2H₂O} (6, sip = 5-sulfoisophthalate) are coordination complexes. Antiferromagnetic superexchange is observed in 1 and 4, with concomitant zero-field splitting. Thermal decomposition behavior of the higher dimensionality complexes is also discussed.     

Control of topology and dimensionality by aromatic dicarboxylate pendant arm position and length in cadmium coordination polymers incorporating a hydrogen-bonding capable kinked dipyridine ligand

Hydrothermal synthesis has afforded three cadmium coordination polymers incorporating both an aromatic dicarboxylate ligand and the kinked and hydrogen-bonding capable organodiimine 4,4′-dipyridylamine (dpa). The positions and length of the pendant arms of the aromatric dicarboxylate moiety exerts a strong structure directing effect in this system. {[Cd(hmph)(dpa)] · H₂O}_n (1, hmph = homophthalate) possesses interdigitated herringbone (6,3) grid layers with an ABAB stacking pattern. {[Cd(1,3-phda)(dpa)(H₂O)] · 0.5H₂O}_n (2, 1,3-phda = 1,3-phenylenediacetate) exhibits a (4,4)-grid layer structure with two different aperture sizes and an unusual ABCD layer stacking pattern. Shortening the pendant arm length resulted in an uncommon CdSO₄-type (6⁵8 topology) 4-connected 3-D network in {[Cd(iph)(dpa)] · 4H₂O}_n (3, iph = isophthalate), whose uncoordinated water molecules occupy a sizable incipient void space of 23.7% of the unit cell volume. All three coordination polymers underwent blue-violet luminescence under ultraviolet irradiation.     

Topological diversity in copper aromatic meta-dicarboxylate coordination polymers with bis(pyridylformyl)piperazine coligands

Hydrothermal synthesis has afforded divalent copper coordination polymers containing bis(4-pyridylformyl)piperazine (4-bpfp) tethers and aromatic meta-dicarboxylate ligands. {[Cu(ip)(4-bpfp)]·2H₂O}_n (1, ip = isophthalate) possesses a (4, 4) rectangular grid structure with an unusual ABCD stacking pattern along a 4₁ screw axis. Sterically bulky substituents in the 5-position of the isophthalate ligands reduced the coordination polymer dimensionality, with [Cu₂(tBuip)₂(4-bpfp)(H₂O)₂]_n (2, tBuip = 5-tert-butylisophthalate) and {[Cu(MeOip)(HMeOip)₂(4-bpfp)]·3H₂O}_n (3, MeOip = 5-methoxyisophthalate) displaying 1D polymeric ladder and chain motifs, respectively. Compound 3 possesses a rare twofold interpenetrated binodal supramolecular hms net with (6³)(6⁹8) topology. Longer meta-disposed acetate pendant arms induced a doubly interpenetrated 3D primitive cubic topology in {[Cu₂(1,3-phda)₂(H₂O)₂(4-bpfp)]}_n (4, 1,3-phda = 1,3-phenylenediacetate), which possesses antiferromagnetically coupled {Cu₂O₂} kernels (J = −6.14(8) cm⁻¹).     

One-dimensional nickel and cobalt phthalate coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine: Hydrothermal synthesis, structural characterization and thermal properties

Hydrothermal synthesis has afforded a family of three structurally related metal phthalate (pht) 1-D coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine (dpa), with a general formulation of [L₂M(dpa)₂M(H₂O)₄] · H₂O (L = pht, M = Co, 1, M = Ni, 2; L = 4-methylphthalate (4-mpht), M = Co, 3). Single crystal X-ray diffraction of 1 and 2 revealed the presence of one-dimensional (1-D) polymeric chains consisting of [M(H₂O)₄]²⁺ and [M(pht)₂]²⁻ subunits linked through dpa tethers. These chains in turn conjoin into pseudo 2-D layers and 3-D networks via extensive supramolecular hydrogen bonding pathways. An extremely similar structure is observed for 3 despite the presence of the bulkier methyl group substituent. 1-3 were further characterized via infrared spectroscopy and elemental and thermogravimetric analysis. 1-3 represent the first dicarboxylate coordination polymers incorporating dpa tethering ligands.     

Coordination geometry induced control of channel morphology in divalent metal pyridinedicarboxylate coordination polymers containing a kinked tethering organodiimine

Hydrothermal synthesis has afforded two divalent metal coordination polymers incorporating tridentate 2,6-pyridinedicarboxylate (PDC) ligands and the kinked dipodal organodiimine 4,4′-dipyridylamine (dpa), {[Ni(PDC)(dpa)(H₂O)] · 2H₂O} (1) and {[Zn(PDC)(dpa)] · 3H₂O} (2), which were characterized by single crystal X-ray diffraction and spectral and thermogravimetric analyses. Although both 1 and 2 display one-dimensional (1-D) polymeric chain motifs, the different coordination environments (octahedral in 1, distorted square pyramidal in 2) provoke divergence in the structures and aggregations of the chain subunits. Compound 1 manifests both polycatenation and interdigitation of its 1-D polymeric chains, while 2 exhibits only interdigitation, resulting in widely disparate morphologies for water molecule-bearing channels within the extended structures. Compound 1 possesses three distinct channel types occupied by isolated water molecules. Compound 2 presents only one type of channel, larger than those in 1, filled with D(5) discrete-chain water molecule aggregations. In both cases the co-crystallized water molecules are anchored to the coordination polymer matrix by hydrogen bonding involving PDC carboxylate oxygen atoms and the central amine unit of the dpa ligands. These supramolecular interactions are crucial for stability, as 1 and 2 both undergo irreversible loss of crystallinity upon dehydration.     

Hydrothermal synthesis, crystal structures and photoluminescent properties of four cadmium(II) coordination polymers derived from diphenic acid and auxiliary ligands

Four novel metal coordination polymers, [Cd(dpa)(H₂O)]_n (1), [Cd(dpa)(2,2′-bipy)]_n (2), {[Cd₂(dpa)₂(4,4′-bipy)₃](4,4′-bipy)(H₂O)₂}_n (3) and [Cd(dpa)(bim)₂(H₂O)]}_n (4) (H₂dpa = 2,4′-biphenyl-dicarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, bim = benzimidazole), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses reveal that the 2,4′-diphenic acids acts as bridging ligands, exhibiting rich coordination modes to link metal ions: bis-monodentate, bidentate chelating, chelating/bridging, monoatomic bridging and monodentate modes. In addition, the luminescent properties for compound 1-4 are also investigated in this work.     

Divalent metal 1,3-phenylenediacetate coordination polymers with rigid or flexible dipyridyl tethers: Chains, layers, and interpenetrated networks

Hydrothermal synthesis has afforded four divalent metal 1,3-phenylenediacetate (1,3-phda) coordination polymers containing different dipyridyl-type ligands. {[Cu(1,3-phda)(dpa)(H₂O)]·H₂O}_n (1, dpa = 4,4′-dipyridylamine) exhibits a simple 2-D (4,4) rhomboid grid structure. {[Co(1,3-phda)(bpy)]·1.5H₂O}_n (2, bpy = 4,4′-bipyridine) also possesses a (4,4) layer structure, but with syn-syn bridged {Co₂(OCO)₂} dimeric kernels serving as 4-connected nodes. {[Co(H₂O)₄(3-bpmpH₂)](1,3-phda)₂·8H₂O}_n (3, 3-bpmp = bis(3-pyridylmethyl)piperazine) manifests cationic 1-D [Co(H₂O)₄(3-bpmpH₂)]_n⁴ⁿ⁺ chains linked into higher dimensionality by unligated 1,3-phda anions and curled tetrameric water molecule units. {[Ni(1,3-phda)(4-bpmp)(H₂O)₂]·2H₂O}_n (4, 4-bpmp = bis(4-pyridylmethyl)piperazine) has an underlying twofold interpenetrated 6⁵8 (cds) 3-D network topology. Variable temperature magnetic susceptibility studies revealed the presence of weak antiferromagnetic coupling and zero-field splitting (J = −1.65(4) cm⁻¹ and D = 30.9(7) cm⁻¹ with g = 2.20(1)) within the {Co₂(OCO)₂} dimers in 2.     

Zinc maleate and fumarate coordination polymers containing hydrogen-bonding capable organodiimines featuring ligand dependent in situcis-trans isomerization

Solution phase reaction at ambient temperature of zinc nitrate, maleic acid and 4,4′-dipyridylamine (dpa) afforded {[Zn₂(maleate)₂(dpa)₂]·5H₂O}_n (1), which displayed parallel (4,4)-grid like coordination polymer layers interdigitated into double layer slab motifs via hydrogen bonding. A similar reaction employing bis(4-pyridylmethyl)piperazine (bpmp) caused in situcis-trans isomerization of maleic acid to fumarate, and generation of [Zn(fumarate)(bpmp)(H₂O)₂]_n (2). Compound 2 also manifested (4,4)-grid coordination polymer layers similar to those in 1; however, the larger apertures in 2 permit 2d + 2d → 3D mutually inclined interpenetration. Thermogravimetric and luminescence studies are also reported for 1 and 2.     

Synthesis, structure and magnetic properties of a pair of copper dicarboxylate/dipyridylamine coordination polymers with a non-interpenetrated CdSO4 topology

Hydrothermal synthesis has afforded a pair of divalent copper coordination polymers containing the kinked and hydrogen-bonding capable imine 4,4′-dipyridylamine (dpa) and aromatic dicarboxylates, {[Cu(iph)(dpa)]·0.5H₂O}_n (1, iph = isophthalate) and [Cu(tdc)(dpa)]_n (2, tdc = 2,5-thiophenedicarboxylate). Compounds 1 and 2 contain orthogonally disposed parallel sets of 1-D [Cu(iph)]_n and [Cu(tdc)]_n chains, respectively, containing dicarboxylate-bridged dinuclear {CuOCO}₂ units. The chain motifs are joined by tethering dpa ligands to construct uncommon non-interpenetrated 3-D CdSO₄ lattices (6⁵8 topology) in both cases. Variable temperature magnetic studies show the presence of weak antiferromagnetic coupling within the {CuOCO}₂ dimers in both complexes, with J = −2.66(3) and −1.68(5) cm⁻¹ for 1 and 2, respectively.     

Exploring the effect of chain length of bridging ligands in coordination complexes and polymers derived from mixed ligand systems of pyridylnicotinamides and dicarboxylates

The supramolecular structural diversities in mixed ligand systems derived from a series of dicarboxylate anions with varying chain lengths and N-donor exo-bidentate ligand equipped with hydrogen bonding capable amide backbone with Co(II)/Zn(II) metal centers are analyzed. In this context, two complexes namely (Co(L1)₂(malonate)(H₂O)₂} (1a), {Zn(L1)₂(malonate)(H₂O)₂} (1b) and one coordination polymer namely {[Co(μ-L1)(μ-glutarate)(H₂O)] · H₂O}_n (4) (where L1 = N-(4-pyridyl)nicotinamide) have been synthesized and crystallographically characterized. The main aim of this work is to explore the effects of chain lengths of the anionic carboxylate ligands such as malonate, succinate, maleate, and glutarate, in determining the final architecture of coordination compounds based on the mixed ligands. Analyses of the structures revealed that the length of the bridging ligands have prominent effect in the formation of hierarchical structures.     

A series of 1-D to 3-D metal-organic coordination architectures assembled with V-shaped bis(pyridyl)thiadiazole under co-ligand intervention

Six new coordination polymers based on V-shaped linkage 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and transition metal ions, [Co(bpt)(pm)_0.5(H₂O)]_n · 3nH₂O (1), [Cu₂(bpt)(pm)(H₂O)₄]_n (2), [Co(bpt)(pydc)]_n · 2nCHCl₃ · nH₂O (3), [Cu₂(bpt)(pydc)₂(H₂O)₂]_n (4), [Cu₂(bpt)(pydco)₂(H₂O)₂]_n · nH₂O (5) and [Cd(bpt)(pydco)]_n (6) (H₄pm = pyromellitic acid, H₂pydc = pyridine-2,6-dicarboxylic acid, H₂pydco = pyridine-2,6-dicarboxylic acid N-oxide), have been synthesized under the intervention of various polycarboxylate ligands. Complex 1 exhibits a 3-D 4-connected structure with 1-D nanosized open channels encapsulated lots of water molecules. Complex 2 represents a 2-D grid containing two types of rectangular windows. When pydc and pydco instead of pm, complexes 3 and 6 were obtained with highly undulated 2-D layers. The interlayers of 3 are filled with two kinds of solvent molecules, whereas 6 is a double-layered framework without free molecules. Complexes 4 and 5 consist of two distinct 1-D infinite chains held together to form different 2-D supramolecular networks. Importantly, bpt spacer shows changeful conformational geometries and generates complicated crystalline architectures with the introduction of polycarboxylate ligands. Additionally, thermal stability of complexes 1, 3 and 5, fluorescent properties of 6 and X-ray powder diffraction of 1 have also been investigated.     

An oxamato bridged trinuclear copper(II) complex: Synthesis, crystal structure, reactivity, DNA binding study and magnetic properties

A linear tri-nuclear oxamato bridged copper(II) complex [Cu₃(pba)(dpa)₂(H₂O)(ClO₄)](ClO₄)·H₂O (1) (pbaH₄ = 1,3-propanediylbis(oxamic acid), dpa = 2,2′-dipyridylamine) was isolated from the reaction mixture of Na₂[Cu(pba)]·3H₂O, copper perchlorate hexahydrate and dipyridylamine in methanol. On reaction with dpa or DMF in basic medium (KOH) at ambient temperature complex 1 changed to dinuclear oxalate bridged copper(II) derivatives, [Cu₂(μ-C₂O₄)(dpa)₄](ClO₄)₂ (2) and [Cu₂(μ-C₂O₄)(dpa)₂(DMF)₂](ClO₄)₂ (3), respectively. The complexes 1, 2 and 3 have been characterized by physicochemical and spectroscopic tools, and also by the X-ray single crystal analysis. The hydrolysis of 1 in basic medium and thermo-gravimetric analysis has been studied. Absorption and emission spectral studies showed that complex 1 interacts with calf thymus-DNA (CT-DNA) with a binding constant (K_b) of 4.01 × 10⁴ M⁻¹ and linear Stern-Volmer quenching constant (K_sv) of 6.9 × 10⁴. A strong anti-ferromagnetic interaction with a coupling constant J_CuCu of 320.0 ± 0.3 cm⁻¹ was observed from the study of magnetic behavior of complex 1 in the temperature range of 2-300 K. Electrochemical equivalency of three copper(II) ions in 1 was identified by getting only one quasi reversible cyclic voltammogram.     

Stereosensitive formation and interconversion of sulfur-bridged cobalt(III)-mercury(II) polynuclear complexes with d- and/or l-penicillaminates

The reaction of trans(N)-[Co(d-pen)₂]⁻ (pen = penicillaminate) with HgCl₂ or HgBr₂ in the molar ratios of 1:1 gave the sulfur-bridged heterodinuclear complex, [HgX(OH₂){Co(d-pen)₂}] (X = Cl (1a) or Br (1b)). A similar reaction in the ratio of 2:1 produced the trinuclear complex, [Hg{Co(d-pen)₂}₂] (1c). The enantiomers of 1a and 1c, [HgCl(OH₂){Co(l-pen)₂}] (1a′) and [Hg{Co(l-pen)₂}₂] (1c′), were also obtained by using trans(N)-[Co(l-pen)₂]⁻ instead of trans(N)-[Co(d-pen)₂]⁻. Further, the reaction of cis · cis · cis-[Co(d-pen)(l-pen)]⁻ with HgCl₂ in the molar ratio of 1:1 resulted in the formation of [HgCl(OH₂){Co(d-pen)(l-pen)}] (2a). During the formations of the above six complexes, 1a, 1b, 1c, 1a′, 1c′, and 2a, the octahedral Co(III) units retain their configurations. On the other hand, the reaction of cis · cis · cis-[Co(d-pen)(l-pen)]⁻ with HgCl₂ in the molar ratio of 2:1 gave not [Hg{Co(d-pen)(l-pen}₂] but [Hg{Co(d-pen)₂}{Co(l-pen)₂}] (2c), accompanied by the ligand-exchange on the terminal Co(III) units. The X-ray crystal structural analyses show that the central Hg(II) atom in 1c takes a considerably distorted tetrahedral geometry, whereas that in 2c is of an ideal tetrahedron. The interconversion between the complexes is also examined. The electronic absorption, CD, and NMR spectral behavior of the complexes is discussed in relation to the crystal structures of 1c and 2c.     

Magnetic investigation of two helical frameworks derived from mixed ligands

Although the 2,2′-biphenyldicarboxylate ligand (2,2′-dpa) has been widely used to construct metal-organic frameworks (MOFs) with helical sub-structure, the effect of the helical arrangement of spin carriers on the magnetic properties remains rarely scarce. In this article, two unique magnetic metal-organic supramolecular frameworks with different structural features, [Cu₂(dpa)₂(H₂O)₂(4,4′-dpdo)_0.5]_n (1) and [Ni(H₂O)₄(dpa)] · (4,4′-dpdo)(H₂O) (2) (dpdo = 4,4′-dipyridine-N,N′-dioxide), have been isolated from the direct reaction of H₂dpa with their corresponding salts in the presence of dpdo. In complex 1, the Cu-dpa double-helical chains, which are bridged by long flexible μ₂-dpdo ligands to give rise to a regular 6³ covalent layer, exhibit strong antiferromagnetic coupling interactions. Whereas the 1D [Ni(dpa)]_n helical chains in complex 2 exhibit weak antiferromagnetic coupling interactions. Rich hydrogen bonds between perpendicular 1D [Ni(dpa)]_n helical chains and quasi-1D (dpdo)_n chains result in an intricate 3D supramolecular network.     

Metal(II)-organic coordination polymers with two distinct atropisomeric building units from an axially prochiral inner salt through interchain C-H?X hydrogen bonds (X = O, Cl; metal = cobalt, nickel)

Two isostructural photoluminescent metal-organic coordination polymers, namely, [M(H-mpypdc)(Cl)(H₂O)₃]_n (mpypdc = 2,6-dimethyl-4-(pyridin-4-yl)pyridine-3,5-dicarboxylate; M = Co (2) and Ni (3)), were synthesized from H₂mpypdc (1), and characterized by single crystal X-ray analyses. New ligand 1 is an inner salt. In the metal-organic coordination polymeric chains, two distinct S- and R-atropisomeric units are generated from the axially prochiral 1 through C-H?X (X = O, Cl) hydrogen bonds. There have interesting 2D supramolecular networks [M(Cl)(H₂O)₂]_n in the crystal structures of title compounds. The photoluminescence of new compounds are also investigated in solid state at ambient temperature.     

Molecular double chains and 3-D supramolecular frameworks with open channels assembled from 1D copper(II) maleate coordination polymers with chelating aromatic amine ligands by noncovalent interactions

Two 1D coordination polymers, [Cu(mal)(Hdpa)]_n (1) and {[Cu(mal)(tpy)] · 4H₂O}_n (2) (mal = maleate, Hdpa = 2, 2′-dipyridylamine and tpy = 2,2′:6′,2″-terpyridine), have been synthesized and their crystal structures, IR spectra, thermal analyses, magnetic properties were determined. In 1 and 2, the maleate ligands link adjacent metal centers to form 1D coordination polymeric chains. Furthermore, the carboxylate oxygen atoms and the aromatic chelate ligands provide potential supramolecular recognition sites for noncovalent interactions to form higher dimensionality. In 1, each pair of 1D chains recognize each other through strong hydrogen bond formed by active amine (-NH-) hydrogen and aromatic π-π stacking interactions to generate a zipperlike double-stranded chain. In contrast, when the substitutions of tpy for dpa further enhance the π-π aromatic stacking interactions, complex 2 is directly constructed into 2D zipperlike layers by the unprecedented aromatic π-π stacking interactions that same orientated aromatic chelate ligands are simultaneously attached to both sides of the chain and the significant C-H?O hydrogen bonds. These layers are constructed through hydrogen bonds and result in a 3D supramolecular network with 1D open channels, in which exists an unprecedented one-dimensional water chain. Both were magnetically characterized, showing weak ferromagnetic behavior.     

A 3D supramolecular network of cobalt(II)(bis(4-pyridyl)ethylene) with terephthalate dianions

A three dimensional supramolecular network, {[Co(bpee)(H₂O)₄] · (tp) · 2(H₂O)}_n (1) [bpee = trans-1,2 bis(4-pyridyl)ethylene; tp = terephthalate dianion] has been synthesized and characterized by X-ray single crystal structure, magnetic measurement and thermal analysis. The structure determination reveals that the cobalt(II) ions, bridged by bpee and coordinated by four water molecules, give rise to covalently linked 1D polymeric chain. The parallel chains get involved in H-bonding with tp resulting in a 3D architecture. Upon heating 1, which is pink in color, transforms to [Co(bpee)(tp)] (1a, blue). The deaquated species (1a) reverts on keeping in humid atmosphere. Low temperature magnetic data indicate weak antiferromagnetic coupling.     

Syntheses, crystal structures and magnetic properties of two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes

Two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes [Co₂(H₂O)₂(phen)₂(adc)₂]·(C₂H₇N)·2H₂O (1) and [Co(H₂O)(phen)(adc)]·H₂O (2) were synthesized in a mixed solvent under 45 °C (H₂adc = adamantane-1,3-dicarboxylic acid). Compound 1 consists of dinuclear [Co₂(H₂O)₂(phen)₂(adc)₂] complex molecules, dimethylamine (C₂H₇N) molecules and hydrogen-bonded water molecules. The dinuclear molecules, via intermolecular hydrogen bonds, are interconnected into hydrogen-bonded chains along [1 0 0] and interdigitation of phen ligands due to interchain π?π stacking interactions assembles the hydrogen-bonded chains into 2D supramolecular layers parallel to (0 0 1). In compound 2, the Co(II) ions are bridged by adamantane-1,3-dicarboxylate anions to form 1D chains along [0 0 1], and the resulting chains are assembled into double-chains based on interchain π?π interactions. The double-chains are further held together via hydrogen bonds into 2D supramolecular layers parallel to (1 0 0). The variable temperature magnetic measurements show an overall weak antiferromagnetic behavior for 1, and an weak ferromagnetic behavior over 300-75 K followed by antiferromagnetic behavior below 75 K for 2.     

Crystal structures and luminescent properties of zinc(II) and cadmium(II) compounds constructed from 5-sulfoisophthalic acid and flexible bis-triazole ligands

Four new cadmium(II) and zinc(II) coordination polymers {[Zn(btrp)(SIP)][Zn_0.5(H₂O)₃]}_n (1), {[Cd_1.5(btrp)(SIP)(H₂O)₂]·2H₂O}_n (2), {[Cd_1.5(btrb)(SIP)(H₂O)₃]·2H₂O}_n (3), {[Zn_1.5(btrb)_1.5(SIP)(H₂O)₂]·2H₂O}_n (4) (btrp = 1,3-bis(1,2,4-triazol-1-yl)propane, btrb = 1,3-bis(1,2,4-triazol-1-yl)butane, NaH₂SIP = 5-sulfoisophthalic acid monosodium salt) have been synthesized under hydrothermal conditions and structurally characterized. Compound 1 possesses an infinite 1D ladder-like chain structure with [Zn(H₂O)₆]²⁺ trapped in the pores, which is further interconnected by π?π interactions to lead to a 2D supramolecular architecture. Compounds 2 and 3 features two similar 2D layer structures, and the resulting 2D structures are interconnected by hydrogen-bond interactions to lead to 3D supramolecular architectures. Compound 4 is a 2D parallel ladder structure, and through the interpenetrating btrb ligand, it constructs into 3D architectures. Luminescence analyses were performed on all the four compounds, which show strong fluorescent emissions in the solid state at room temperature.     

Four metal-organic networks based on benzene-1,4-dioxyacetic acid and dipyrido[3,2-a:2′,3′-c]phenazine ligand

Four structurally diverse complexes, [Cd(dppz)(bdoa)]_n (1), [Zn(dppz)(bdoa)(H₂O)]_n (2), [Fe(dppz)₂(bdoa)]_n·2nH₂O (3), and [Co₂(dppz)₂(bdoa)₂(H₂O)]_n·3nH₂O (4), where H₂bdoa = benzene-1,4-dioxyacetic acid and dppz = dipyrido[3,2-a:2′,3′-c]phenazine, have been hydrothermally synthesized. Compounds 1-4 feature chain structures. There exist π-π interactions in the structures of 1, 2 and 4. Two neighboring chains of 1 are linked through the π-π interactions into a double chain supramolecular structure. The chains of 2 and 4 are further extended by the π-π interactions to form 3D and 2D supramolecular structures, respectively. The structural differences among such complexes show that the transition metals have important influences on their structures. The photoluminescent property of complex 2 and the magnetic property of complex 4 have also been investigated.