3D Supramolecular Architecture Research Articles

Synthesis, structure and photoluminescence properties of heterometallic-based coordination polymers of trimesic acid.

Reacting trimesic acid (H3TMA, C9H6O6) with CaCl2 and MCl2 at 110 °C under hydrothermal conditions gave the isostructural heterobimetallic coordination polymers (CPs) catena-poly[[tetraaquazinc(II)]-μ-5-carboxybenzene-1,3-dicarboxylato-[tetraaquacalcium(II)]-μ-5-carboxybenzene-1,3-dicarboxylato], [CaZn(HTMA)2(H2O)8]n, 1, and catena-poly[[tetraaquacobalt(II)]-μ-5-carboxybenzene-1,3-dicarboxylato-[tetraaquacalcium(II)]-μ-5-carboxybenzene-1,3-dicarboxylato], [CaCo(HTMA)2(H2O)8]n, 2. Compounds 1 and 2 crystallize in the monoclinic space group C2/c. The solid-state structures consist of eight-coordinate CaII ions and six-coordinate MII ions. These ions are connected by a doubly deprotonated HTMA2- ligand to create a one-dimensional (1D) zigzag chain. Poly[[decaaquabis(μ3-benzene-1,3,5-tricarboxylato)calcium(II)dizinc(II)] dihydrate], {[CaZn2(TMA)2(H2O)10]·2H2O}n, 3, was found incidentally as a minor by-product during the synthesis of 1 at a temperature of 140 °C. It forms crystals in the orthorhombic space group Ccce. The structure of 3 consists of a two-dimensional (2D) layer composed of [Zn(TMA)] chains that are interconnected by CaII ions. The presence of aromatic carboxylic acid ligands and water molecules, which can form numerous hydrogen bonds and π-π interactions, increases the stability of the three-dimensional (3D) supramolecular architecture of these CPs. Compounds 1 and 2 exhibit thermal stability up to 420 °C, as indicated by the thermogravimetric analysis (TGA) curves. The powder X-ray diffraction (PXRD) data reveal the formation of unidentified phases in methanol and dimethyl sulfoxide, while 1 exhibits chemical stability in a wide range of solvents. The luminescence properties of 1 dispersed in various low molecular weight organic solvents was also examined. The results demonstrate excellent selectivity, sensitivity and recyclability for detecting acetone molecules in aqueous media. Additionally, a possible sensing mechanism is also outlined.

Synthesis and characterization of a europium coordination polymer as a fluorescent sensor for the selective detection of PO43−, DTZ, and NFT

A new europium coordination polymer [Eu(2,3′-oba)(2,3′-Hoba)(IP)]n (Eu-CP) has been synthesized by hydrothermal reaction using 2,3′-oxbis (benzoic acid) (2,3′-H2oba) and 1H-imidazole [4,5-f] [1,10]-phenanthroline (IP). The semi-rigid ligand 2,3′-H2oba and large rigid ligand IP form a 1D chain structure of the Eu-CP, which is further stacked into a 3D supramolecular architecture through C–H⋯O and O–H⋯N hydrogen bonding. Below 400 °C, the Eu-CP does not decompose. It shows good chemical stability in common solvents and aqueous solutions with pH in the range of 3–12. The Eu-CP emits strong red luminescence, attributed to the 5D0→7FJ (J = 0–4) transitions of the Eu3+ ion. The luminescence quantum yield and lifetime are 61% and 0.94 ms, respectively. The Eu-CP has a broad absorption in the range of 200–400 nm, with a maximum excitation wavelength of 365 nm. Furthermore, Eu-CP is used as a sensor for the detection of PO43−, dimetridazole (DTZ), and nitrofurantoin (NFT) in aqueous systems, and NFT in biological samples (calf serum) based on the luminescence quenching effect. Notably, luminescent Eu-CP@film was prepared for sensing PO43−, NFT, and DTZ, which can be reused more than 20 times, facilitating a visually simple and rapid online detection platform. In addition, we also studied the luminescence quenching mechanism of Eu-CP by analytes.

Syntheses, structures and electrochemical properties of two novel 2D Co-MOFs

Two novel two-dimensional Co-MOFs were prepared by solvent-thermal method using cobalt nitrate and 5-amino-isophthalic acid (H2L) as raw materials. The molecular formula of [Co0.5(HL)]·1.5 H2O and [Co0.5(HL)(H2O)]·H2O correspond to Co-MOF-1 and Co-MOF-2. And they possess monoclinic symmetry in I2/a and C2/c space group respectively. S-XRD, P-XRD, XPS and SEM were used to identify the structures and valence. Co-MOF-1 and Co-MOF-2 exhibit two-dimensional (2D) layer structure. The difference between the two compounds is that the layers of the Co-MOF-1 are further connected by hydrogen-bonds to give rise to a 3D supramolecular architecture. A three-electrode system was used to measure the electrochemical properties of the two samples. As the electrode material for supercapacitors, the specific capacitance of Co-MOF-1 can reach 316 F/g at 1 A/g, while for Co-MOF-2, the specific capacitance can reach 350 F/g under the same test conditions.

A 3D supramolecular framework-based electrochemical sensor for highly sensitive detection of ascorbic acid

A benzimidazole carboxylate ligand with multiple coordination sites has been designed by the aldimine condensation reaction of 2-pyridinecarboxal-dehyde and 3,4-diaminobenzoic acid, 2-(2′-pyridyl)-benzimidazole-6-carboxylic acid (H2pybimc), which solvothermally assembled with Ni2+ ions in the mixed solvents of H2O and n-propanol to generate a 3D supramolecular framework, {[Ni(Hpybimc)(NO3)(H2O)]}n (CP 1). The chemical composition and structure of CP 1 have been characterized in detail by various tools. Structural analysis demonstrates that the asymmetrical unit of CP 1 consists of one octahedral Ni2+ ion, one Hpybimc−, one NO3− and one coordinated water molecule. Adjacent Ni2+ ions are linked by Hpybimc− to form a 2D 3-connected ‘fes’-type topology, which further generates a 3D supramolecular architecture by hydrogen bonds and π···π stacking interactions. The carbon paste electrode (CPE) modified with CP 1 is fabricated (CPE 1) and applied for the electrochemical sensor of ascorbic acid (AA), which exhibits good linear correlation with AA in the concentration range of 5.0 × 10−4 to 7.3 mmol L−1 with the limit of detection (LOD) of 0.85 μmol L−1. Moreover, it has satisfactory stability, repeatability, and selectivity towards AA, which can be successfully used for the detections in real samples.

3D Ag(I) coordination polymer sandwiched by water-muconate anionic layers: Synthesis, structure, Hirshfeld surface analysis, binding with BSA, and photocatalytic activity

The sonochemical reaction between silver salt, 1,3-bis(4-pyridylpropane (bpp) and trans,trans-muconic acid (H2muc) formed an Ag(I) coordination polymer with a 3D supramolecular sandwich architecture, {[Ag8(bpp)8(H2O)3].(muc)4.29(H2O)}n, (1) consisting of the silver-bpp cationic host that alternates with 2D water–muc guest anionic layers. The latter is formed by H-bonded water molecules-anions comprising hexagonal (H2O)6 clusters. The Hirshfeld surface and fingerprint plots have been used to quantify the weak intermolecular interactions in the crystal packing arrangement. The study showed that intermolecular hydrogen bonds are the most critical in constructing the titled supramolecular complex, accounting for 51.2% of the total Hirshfeld surface. Several spectrofluorimetric methods have been employed to investigate the binding interaction between Bovine Serum Albumin (BSA) and the titled complex. The complex induced significant fluorescence quenching of BSA, indicating a strong binding affinity for the protein. Static or ground state complex formation was envisaged as the primary quenching mechanism when the complex interacts with BSA. In addition, the Ag compound also offers photocatalytic properties by degrading the toxic organic methylene blue dye.

A combined experimental and theoretical studies of two new Co(II)–PDA complexes: Unusual 2D and 3D supramolecular networks [PDA = 2,6-pyridinedicarboxylic acid

Two new Co(II) complexes, {[Co(2,6-pydc)2]·[Co(4,4′-tmdpy)(H2O)4]n·2H2O}(1) and {2[Co(2,6-pydc)2]2-·[2(4,4′-bpy]2+·10(H2O)·O}(2) [2,6-pydc = 2,6-pyridinedicarboxylic acid, 4,4′-tmdpy = 4,4′-trimethylenedipyridine, 4,4′-bpy = 4,4′-Bipyridine] were designed, synthesized, and characterized using elemental analysis, spectroscopic techniques, and single-crystal X-ray diffraction analysis. For complex (1), hydrogen bonding, π⋅⋅⋅π and lone pair (l.p.)···π interactions produce supramolecular assemblies, whereas for complex (2), hydrogen bonding, π⋅⋅⋅π, π⋅⋅⋅π+, π+⋅⋅⋅π, l.p···π play the pivotal role in building final solid-state structure. Complex (1) exhibits a unique 3D supramolecular architecture generated through π⋅⋅⋅π and l.p···π interactions. Complex (2) also exhibits a unique (l.p···π/π⋅⋅⋅π+/π+⋅⋅⋅π/π⋅⋅⋅π/π⋅⋅⋅π+/π+⋅⋅⋅π/π⋅⋅⋅l.p)n self-assembly. The noncovalent interactions were characterized through Bader’s quantum theory of “Atoms In Molecules” (QTAIM). Evaluation of topological parameters at (3, –1) bond critical points (BCPs) confirmed the 'closed-shell' nature of the intermolecular interactions. Furthermore, the theoretical “Noncovalent Interaction” (NCI) plot index was used to characterize noncovalent interactions.

Metal organic frameworks based on mixed ligands: Syntheses, structures and selective detection of nitro explosive TNP, metal ions Fe3+ Cu2+ and CrO42-

Three new MOFs [Cd(2,5-bipi)(5-hip)]n (1), [Mn(2,5-bipi)(1,3-bdc)]n (2), and [Co(2,5-bipi)(1,3-bdc)(DMF)]n (3) (2,5-bipi = 2,5-bis(1-imidazoly)pyridine, 5-H2hip = 5-hydroxyisophthalic acid, 1,3-H2bdc = isophthalic acid) have been successfully synthesized under solvothermal conditions. They were characterized by elemental analysis, FT-IR spectra, X-ray single-crystal diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA). The results suggest that the linkage of different ligands with metal ions affords a 4-connected layer. And these 2D networks are extended to the final 3D supramolecular architectures by CH∙∙∙π stacking interactions. Fluorescence sensing measurements showed that MOF 1 can detect TNP, Fe3+, Cu2+ and CrO42− ions with high selectivity and sensitivity. In addition, their possible quenching mechanisms were studied in detail.

Synthesis, Spectroscopic Analysis, Charge and Proton Transfer Interaction Studies, In-Vitro, and In-Silico Antimicrobial, Pharmacokinetics Studies of Piperazin-1-Ium 4-Aminobenzoate Monohydrate: A Density Functional Theory Approach

Piperazin-1-ium 4-aminobenzoate monohydrate (PPAB) single crystals were grown by slow evaporation method. The grown crystal PPAB has been characterized by single-crystal X-ray diffraction, FTIR, FT-Raman, and UV-visible analysis. The B3LYP method and 6-311G (d, p) basis set were used to optimize the structure. The title compound was investigated theoretically and experimentally by FT-IR, FT-Raman, and UV-Vis spectral analysis. The presence of various functional groups in the structure was elucidated by FTIR and FT-Raman spectral studies. The intermolecular interactions within the crystal structure were investigated using Hirshfeld surface analysis. The crystal packing diagram reveals interesting non-covalent interactions involving C–H···O, N–H···O, and N–H···N hydrogen bonds, leading to the generation of 3D supramolecular architecture. The charge transfer within the molecule was deeply analyzed by using the NBO approach. The molecular electrostatic potential (MEP) and the local reactivity descriptors, such as Fukui function (fk +, fk −) analyses were performed to determine the reactive sites within the molecule. The HOMO and LUMO analysis was used to determine the chemical reactivity and bioactivity of the molecule. Hole-electron analysis was performed to analyze the charge transfer in an excited state. Based on the hole-electron analysis, the inter-fragment charge transfer (IFCT) analysis establishes the amount of charge transfer among different fragments. Topological analyses, such as AIM, RDG, and ELF were carried out to identify the non-covalent interaction within the molecule. The molecular docking studies of the molecule are performed to investigate the binding affinity of the ligand with the protein receptor. Drug-likeness properties, such as Lipinski’s rule of five, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) have been investigated by in silico web-based tools like SwissADME and ADMETlab.

Structural characterization, thermal stability, and solvent de‐/ad‐sorption behavior of two d10 M(II) (M = Cd and Zn) coordination polymers constructed by 1,3,5‐tris(4‐pyridylsulfanyl‐methyl)‐2,4,6‐trimethyl‐benzene (L1)

AbstractTwo d10 M(II) (M = Cd and Zn) coordination polymers (CPs) with chemical formulas, {[Cd(L1)(NCS)2(H2O)]⋅C2H5OH}n (1), and {[Zn(L1)(NCS)2]⋅C2H5OH⋅0.5H2O}n (2) (L1 = 1,3,5‐tris(4‐pyridylsulfanylmethyl)‐2,4,6‐trimethylbenzene) were synthesized and structurally characterized by single‐crystal x‐ray diffraction method. In compound 1, the coordination environment of Cd(II) ion is distorted octahedral bonded to three nitrogen donors from three L1 ligands located in a facial‐position, two nitrogen donors from NCS− and one water molecule. The L1 acts as a bridge ligand with tris‐monodentate coordination mode in a cis‐cis‐cis structural conformation, connecting the Cd(II) to form a two‐dimensional (2D) zigzag‐like layered metal‐organic frameworks. Adjacent 2D layers are then arranged orderly in an ABAB manner to complete its three‐dimensional (3D) supramolecular architecture. In compound 2, the coordination environment of Zn(II) ion is distorted tetrahedral bonded to two nitrogen donors from two L1 ligands and two nitrogen donors from two NCS− ligands. The L1 acts as a bridge ligand with bis‐monodentate coordination mode in a cis‐cis‐cis structural conformation, connecting the Zn(II) ions to form a one‐dimensional (1D) zigzag‐like polymeric chain. Adjacent chains are arranged orderly in an alternate ABAB manner to generate a 2D framework and then further arranged in an AAA manner to complete its 3D supramolecular architecture. The structural characterization as well as thermal‐stability and solvents de‐/ad‐sorption behavior of 1 and 2 are studied and discussed in details.

Four Novel Cobalt(II) Coordination Polymers Based on Anthracene-Derived Dicarboxylic Acid as Multi-functional Fluorescent Sensors toward Different Inorganic Ions

A series of Co(II)–H2L coordination polymers were prepared with different auxiliary ligands, namely {[Co(L)(bibp)]}n 1, {[Co(L) (bpy)(H2O)]2·2H2O}n 2, {[Co(L)(bipd)]}n 3, and {[Co(L)(bbibp)]·H2O}n 4 (H2L = 5-{(anthracene-9-ylmethyl)amino}isophthalic acid, bibp = 4,4′-bis(imidazolyl)biphenyl, bpy = 2,2′-bipyridine, bipd = 3,5-bis(1-imidazoly)pyridine, and bbibp = 4,4′-bis(benzoimidazo-1-yl)biphenyl), by a similar solvothermal method. X-ray diffraction analyses revealed that 1, 3, and 4 exhibit a two-dimensional (2D) structure, which further builds the three-dimensional (3D) supramolecular architecture via the weakly interacting hydrogen bonds of C–H···O, while 2 displayed a one-dimensional (1D) double-chain architecture extended from two 1D zigzag chains by intermolecular hydrogen bonding interactions. The sensing experiments revealed that 1 and 2 can serve as either individual- and/or multi-responsive sensors to selectively detect Cr3+, Al3+, and Pb2+ ions through the fluorescence turn-on effect, while 3–4 exhibited fluorescence turn-off sensing behavior for Fe3+ ions. Moreover, 1–4 can effectively detect and recognize Cr2O72– and CrO42– due to their high selectivity and sensitivity for fluorescence quenching in aqueous solutions, and the sensing mechanism for various ions has been discussed.

Structural Engineering and Electronic Properties of Halide-Specific Supramolecular Architectures: Effective for Stabilizing H5O2+and Fabricating Semiconducting Photoresponsive Diodes

Two different halides containing chloride- and bromide-assisted dissimilar crystalline supramolecular building blocks of 4′-(1H-imidazol-2-yl)-4,2′:6′,4″-terpyridine (ITP) have been achieved. The dissimilar supramolecular associations with hydrogen-bonded networks have been engineered by the role of halides in the ITP-based crystal systems (i.e., ITP-Cl and ITP-Br for Cl– and Br–, respectively). Hirshfeld surface analyses of these supramolecular assemblies have been performed. The π-systems of protonated pyridine and imidazole rings play a pivotal role in establishing the noncovalent π···π type supramolecular interactions in both the crystals, and the π-system-directed associations certainly assist in forming the 3D supramolecular architectures of ITP-Cl and ITP-Br in the solid state. Most intriguingly, the supramolecular association of ITP-Cl uniquely stabilizes the cationic unit of hydroxonium hydrate (i.e., H5O2+) in the solid state, and such solid-state stabilization of H5O2+ by the imidazole-connected terpyridine-based system is one of the pioneering challenges in crystal engineering. Distinctly, the hydrogen-bonded cluster-like assembly of H5O2+ and Cl– has been observed in the ITP-Cl system through hydrogen donor–acceptor balance. Subsequently, a special drive has been endeavored to unveil the semiconducting features, including the charge transport property and photoresponsive behavior, of these synthesized ITP-Cl and ITP-Br-based devices. Fascinatingly, the chloride-mediated ITP-Cl-based device shows remarkably higher electrical conductivity with respect to the ITP-Br-based device under photoirradiation conditions, and this implies the tuning effect of different halides toward the applicability of thin-film-based device performance. The device efficiency-based experimental outcomes have been rationalized through a density functional theory-level analysis.

Solvothermal synthesis of two novel Co(II)-based coordination polymers for the efficient UV-light-driven degradation of methyl violet and magnetic properties

Two novel Co(II) coordination polymers (CPs), formulated as {[Co2(L)(H2O)6]·H2O}n (1) and {[Co(bidpe)2(H2O)2]·H2L·3.5H2O}n (2) (H4L = 3,5-bis(3,4-dicarboxylphenoxy)pyridine, bidpe = 4,4′-bis(lmidazolyl)diphenyl ether), have been solvothermally synthesized and characterized by various techniques. Complex 1 exhibited a 2D→3D supramolecular framework through H-bonds with a point symbol of (12)(4·125)(4) topology. However, with the introduction of additional bibpe ligand, the H4L ligand did not coordinate with Co(II) ions in the synthesis of 2. Complex 2 possessed a 1D [Co(bidpe)2]n loop line, which was further linked by H-bonds to form a 3D supramolecular architecture. In particular, both the CPs exhibited efficient photocatalytic activities towards the degradation of methyl violet (MV) under low-energy irradiation of a 125 W Hg lamp, which could be attributed to their high efficiencies in generating ·OH radicals. Moreover, the variable-temperature magnetic analyses indicated that 1 and 2 exhibit antiferromagnetic behavior between the adjacent Co(II) ions.

Proton-Conductive and Electrochemical-Sensitive Sensing Behavior of a New Mn(II) Chain Coordination Polymer

In this work, a novel Mn(II) chain coordination polymer (Mn-CP), {[Mn(iip)(2bbpum)0.5(H2O)3]·2H2O}n [H2iip = 5-iodoisophthalic acid, 2bbpum = N,N′-bis(2-pyridinemethyl)oxamide] was synthesized under ambient conditions. Mn-CP further assembles into a 3D supramolecular architecture through hydrogen bonds, halogen bonds, and ππ stacking interactions. The composite Mn-CP/nafion membrane has low activation energy for proton transfer, which results in its temperature-insensitive proton conductivity. The cyclic voltammetry demonstrates that the Mn-CP electrode (Mn-CP/GCE) shows quite different redox properties in 0.1 M H2SO4 and 0.1 M PBS aqueous solutions. The Mn-CP/GCE exhibits a couple of irreversible redox peaks with an oxidation peak potential suitable for the nitrite oxidation in 0.1 M H2SO4. Quite differently, in the PBS aqueous buffer solution, the Mn-CP electrode has a couple of irreversible redox peaks. The reduction peak potential is appropriate for the H2O2 reduction. So, the Mn-CP/GCE can be used not only in the electrocatalytic oxidation of NO2– but also in the electrocatalytic reduction of H2O2. The amperometric response reveals that the Mn-CP/GCE exhibits high-selective and extremely sensitive oxidation sensing of NO2– and reduction sensing of H2O2. The exponential detection range is 0.01–20 mM for NO2– and 0.01–10.5 mM for H2O2. The linear detection range for both H2O2 and NO2– is 0.01–0.10 mM. The detection limit is 1.865 μM for NO2– and 8.57 μM for H2O2. The Mn-CP/GCE exhibits high electrochemical stability and fine reproducibility. Moreover, the strategy can be translated to a portable screen-printed electrode (SPE). The Mn-CP/SPE shows more sensitive sensing to NO2– and H2O2 than Mn-CP/GCE. Moreover, it can detect NO2– and H2O2 efficiently in the real-world samples. So, Mn-CP may be a potential dual nonenzymatic electrochemical sensory material for NO2–via oxidation sensing and H2O2via reduction sensing.

Structural characterization and solvent vapor sorption of two solvent-dependent Zn(ii) supramolecular architectures based on a flexible tripodal thioether-based pyridyl ligand and a dicarboxylate-based ligand

Two solvent-dependent 3D supramolecular architectures, constructed by doubly-interpenetrating layered 2D MOF and triply-interpenetrating 3D MOF, respectively, showed interesting reversible solvent vapor ad-/desorption behaviors.

Syntheses, Structural Insight and HirshFeld Surface Analysis of Two Heteroleptic Coordination Polymer of Cu(II)

Using a solvothermal method, we have synthesized two coordination polymers of Cu(II). One is a 1D polymer {[Cu(bpy)(NDC)(H 2 O)].2H 2 O} n (1, 1D) formed with 1,8-naphthalene dicarboxylic acid (H 2 NDC) and 2,2′ -bipyridine (bpy) as an auxiliary ligand, while the other is a 2D polymer {[Cu 3 (TMA)(Imd) 3 ].5H 2 O.2DMF} n (2, 2D) formed with trimellitic acid (H 3TMA) and imidazole (Imd) as an auxiliary ligand. Both coordination polymers 1 and 2 were formed through an in situ hydrolytic ring opening reaction of 1,8-naphthalic anhydride and trimelitic anhydride with bipyridine and imidazole ligands, respectively. The asymmetric unit of polymer 1 contains asymmetric η 1 binding mode (one of the carboxylate) linking distorted square-pyramidal [Cu(NDC)(bpy)(H 2 O)] 2+ coordination units. The syn-syn-η 1 :η 1 linear polymer conformation exist in the 1D coordination polymer with adjacent Cu…Cu distance is 6.849Å. A chain of cyclic tetrameric water clusters is present between the stacked layers of the 3D supramolecular structure. The formation of the 3D supramolecular structure is guided by various weak interactions such as OH…O, CH…O, CH…π and π…π interactions. The coordination polymers 2 forms 3D supramolecular architecture guided by various weak interactions such as OH…O, CH…O and NH…O interactions. The crystal structures of both coordination polymers have been determined using single crystal X-ray diffraction and their structural features are described.

Supramolecular Diversity, Theoretical Investigation and Antibacterial Activity of Cu, Co and Cd Complexes Based on the Tridentate N,N,O-Schiff Base Ligand Formed In Situ

The four new complexes, [Cu(HL1)(L2)Cl] (1), [Cu(HL1)(L1)]∙Cl∙2H2O (2), [Co(L1)2]∙Cl (3) and [Cd(HL1)I2]∙dmso (4), have been prepared by one-pot reactions of the respective chloride or iodide metal salt with a non-aqueous solution of the polydentate Schiff base, HL1, resulted from in situ condensation of benzhydrazide and 2-pyridinecarboxaldehyde, while a ligand HL2, in case of 1, has been formed due to the oxidation of 2-pyridinecarboxaldehyde under reaction conditions. The crystallographic analysis revealed that the molecular building units in 1-4 are linked together into complex structures by hydrogen bonding, resulting in 1D, 2D and 3D supramolecular architectures for 1, 2 and 4, respectively, and the supramolecular trimer for 3. The electronic structures of 1-4 were investigated by the DFT theoretical calculations. The non-covalent interactions in the crystal structures of 1-4 were studied by means of the Hirshfeld surface analysis and the QTAIM theory with a special focus on the C-H⋯Cl bonding. From the DFT/DLPNO-CCSD(T) calculations, using a series of charged model {R3C-H}0⋯Cl- assemblies, we propose linear regressions for assessment of the interaction enthalpy (ΔH, kcal mol-1) and the binding energy (BE, kcal mol-1) between {R3C-H}0 and Cl- sites starting from the electron density at the bond critical point (ρ(rBCP), a.u.): ΔH = -678 × ρ(r) + 3 and BE = -726 × ρ(r) + 4. It was also has been found that compounds 1, 3 and 4 during in vitro screening showed an antibacterial activity toward the nine bacteria species, comprising both Gram-positive and Gram-negative, with MIC values ranging from 156.2 to 625 mg/L. The best results have been obtained against Acinetobacter baumannii MβL.

Zn(II)-dicarboxylato-terpyridyl coordination polymer - A ‘Turn on’ fluorogenic platform for Al3+ sensing in aqueous medium and life cell imaging

Recently, coordination polymers (CPs/MOFs) have emerged as a desirable hybrid material for sensing analytes- such as ions, amino acids, nitroexplosives due to their versatility, stability, reusability, economic benefits and sustainability. Herein, [Zn(bdc)(4-Cltpy)(H2O)]n (CP) [4-Cltpy = 4′-Chloro-2,2′:6′,2′′-terpyridine, H2bdc = Benzene-1,4-dicarboxylic acid], a coordination polymer, is structurally characterized. The structure reveals that the bdc2− bridges Zn(II) via dicarboxylato-O and propagates to form a 1D Coordination Polymer. The 1D CP further undergoes Cl⋯Cl interaction to form a 2D sheet and H-bonding and π⋅⋅⋅π interactions help to construct a 3D supramolecular architecture. Photoluminescence study exposes that the CP is weakly emissive while the fluorescence intensity is significantly enhanced upon interaction with Al3+ in aqueous medium even in presence of quenchable ions like Fe3+ and Cr3+. The detection limit (LOD) is 0.2 ± 0.005 µM (3σ/M method) which is much lower than the permissible limit in drinking water recommended by U.S. Environmental Protection Agency (0.2 mg/L or 7.4 µM). The toxicity of CP has been checked by MTT Assay and intracellular imaging of Al3+ is vivid in human breast cancer MDA-MB 231 cells. The reagent is used for real water sample analysis by fluorescence spectroscopic technique.

Exploration of Variable Temperature Magnetism and Electrical Properties of a Pyridyl-isonicotinoyl Hydrazone Bridged Three-Dimensional Mn-Metal–Organic Framework with a Thiophene Dicarboxylato Link

In emerging trends in our technology-dependent society, the applicability of multifunctional coordination polymers (CPs) and metal–organic frameworks is highly stimulating. In search of such chemical compounds, a Mn(II), d5, based metal–organic framework (MOF), {[Mn2(tdc)2(pcih)2(EtOH)]n} (1), has been designed with the coordination of multidentate ligands tdc2– (2,5-thiophene dicarboxylato) and pcih (pyridine-4-carboxaldehyde isonicotinoylhydrazone). The structure determination by single crystal X-ray diffraction has revealed the formation of three-dimensional (3D) supramolecular architecture via the combined nearly perpendicular bridging of pcih and tdc2– ligands. A variable temperature magnetic measurement of 1 shows weak antiferromagnetism (χMT, 9.41 cm3 K mol–1 at 300 K) with two as good as “isolated” Mn(II) centers (S = 5/2 with g ≈ 2.07). Magnetic exchange is considered through 9/10 carboxylato bridged atoms inclusively spanning two Mn(II) centers at a distance of 4.114 Å. Interestingly, the 3D assembly of 1 exhibits electrical conductivity in the semiconducting region (band gap, 3.72 eV; barrier height, 0.65 eV; series resistance, 0.03 Ω). A Schottky barrier diode feature is recorded at a threshold potential of 0.19 V and follows a non-ohmic relation (I α V2), and the conductivity is 3.42 × 10–5 S m–1. A galvanostatic charge–discharge (GCD) experiment measures the moderate specific capacitance of 1 F/g at a 2 mV/s scan rate.

Unusual oxygen…oxygen dichalcogen bond in an oxo-centered trinclear iron coordination cluster

An oxo-centred, carboxylate bridged trinuclear iron(III) coordination cluster, [Fe3O(2-furoate)6(H2O)1.8(NCS)1.2].H2O (1) was prepared by the reaction of FeCl2·4H2O with 2- Furoic acid, and KSCN in mixed solvents (CH3CN: CH2Cl2). The structure of the compound was identified by FTIR, elemental analysis and Single X-ray Crystallography. The trinuclear iron complex is planar in structure with weak intermolecular interactions i.e. O…O, C-H…π or O…π or π…π, can be seen in the structure to form more stable 3D supramolecular architecture with cavity-channels (O…O distance between furoic oxygen = 4.214 Å). Theoretical investigation has been executed and confirmed about the oxygen…oxygen dichalcogen bond. The energy of unconventional O···O chalcogen bond calculated as 0.6 kcal/mole. Further, QTAIM and NCI methods also expose non-covalent interactions. The QTAIM also confirms about the presence of weaker C-H···S hydrogen bonds of ρ oscillating around 0.005 au. The studied iron complex is a rare example of a system stabilized by O ···O dichalcogen bonding interactions.

Synthesis and structural characterization of a novel lead coordination polymer: [Pb(L)(1,3-bdc)]·2H2O

Abstract A novel coordination polymer, [Pb(L)(1,3-bdc)]·2H2O (1), (L = 2-(2,6-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, 1,3-H2bdc = 1,3-benzenedicarboxylic acid) has been successfully prepared under hydrothermal conditions. The structure of 1 is a 1D chain structure, which further stacks together to form a 3D supramolecular architecture by π–π interactions and C–H⋯π interactions. In addition, the thermogravimetric analysis of 1 has been investigated.