Three-dimensional Supramolecular Structure Research Articles

Crystal structure and DNA cleavage properties of a vanadium complex [NH4][VO(O2)2(pm-im)]⋅3H2O containing 2-(1H-imidazol-2-yl)pyrimidine ligand

A new diperoxovanadium compound, [NH4][VO(O2)2(pm-im)]⋅3H2O (1) (pm-im = 2-(1H-imidazol-2-yl)pyrimidine), has been prepared from aqueous solution and its crystal structure has been determined by single-crystal X-ray diffraction. It belongs to the monoclinic P21/n space group with a = 6.798(4) Å, b = 11.468(6) Å, c = 18.073(9) Å, β = 96.020(6)°, V = 1401.3(13) Å3, and Z = 4. The asymmetric unit of 1 consists of a diperoxovanadium [VO(O2)2(pm-im)]− anion, one free NH4 + counterion, and three lattice water molecules, which are further stacked to form a three-dimensional (3D) supramolecular structure through intra- and intermolecular hydrogen bond interactions. The solution stability of the ion ([VO(O2)2(pm-im)]−) was explored using a combination of multinuclear (1H, 13C, and 51V) magnetic resonance and variable temperature NMR in a 0.15 mol L−1 NaCl/D2O solution that mimics physiological conditions. Additionally, the compound exhibits significant DNA cleavage ability under light, and the electrophoretic result shows that the super helix DNA seems to be directly cleaved into single stranded DNA.

Crystallographic, structural elucidation and electronic interactions of novel ampf crystals for biomedicinal use by theory and practice as an anti-diabetic agent

Fumaric acid is the trans-isomer in the structural effectiveness of the titled salt of the Zwitter ionic nature of the entitled specimen as C6H9N2+.C4H3O4−, the fumarate anions are linked to adjacent anions and 2-amino-4 methyl pyridinium cations via N—H…O hydrogen bonds, forming a three-dimensional supramolecular structure of novel and newly developed 2 Amino 4 methyl pyridinium Fumarate (AMPF) single crystals. The crystal structure also shows a weak C—H…O hydrogen bond between adjacent anions. The crystal is of the monoclinic type of system with space group P21/n, molecular weight of the specimen is 224.22 and chemical formula of AMPF is C10H12N2O4. The crystal identified as novel one and is the persuasive candidate for electronic studies by atomic interactions specifically without surface property and for best medication tool for anti-diabetic as significant bio medicinal activity by pyridine and fumarate based on IC50 data for micro as well as nano scalings using alpha amylase and reported here the interaction patterns, simulated pattern, Platon plot also with structural portrayal with ambience and diffusivity.

Co-operative influence of co-crystallized solvent in sustaining supramolecular architectures of Zn(II)/Cd(II) homoleptic pyridyl functionalized dithiocarbamates complexes via non-covalent interactions

Homoleptic pyridyl-3(N) functionalized dithiocarbamate complexes namely, [Zn(L1)2]2 1 (L1 = (C5H4NCH2)2NCS2) and [Cd(L2)2] ∞ 2 (L2 = CH3C6H4CH2NCS2CH2C4H3O) have been synthesized and characterized by elemental analysis and different spectroscopic techniques. Single crystal structural studies reveal that compound 1 is binuclear while, 2 is polymeric structure. The presence of weak interactions between complexes and solvent molecules in the lattice results in one-dimensional and three-dimensional supramolecular structures of 1 and 2 respectively. In the case of complex 2, a rare and significant S···Cl chalcogen bonding interaction was found, which involve the solvent molecule in chain motifs. Complex 2 is a unique example of homoleptic metal dithiocarbamate complexes exhibiting such types of interactions. Complexes showed emission in the solid state. The TGA studies of complexes revealed that complex 1 would be a good precursor for the preparation of ZnS thin film via metal organic chemical vapor deposition (MOCVD).

Synthesis, crystal structure and characterization of two new metal-organic frameworks with 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene and cyclohexane-1,3,5-tricarboxylate ligands

Two new metal-organic frameworks (MOFs) {[Cu3(timb)2(chtc)2]·14H2O}n, (I) and {[Co3(timb)2(chtc)2]·6H2O}n, (II) were hydrothermally synthesized by corresponding metal salt with mixed organic ligands of 1,3,5-tris[(1H-imidazol-1-yl)methyl]benzene (timb) and cyclohexane-1,3,5-tricarboxylic acid (H3chtc). Crystal structural analysis reveals that they exhibit varied structures. In the MOFs (I), CuII adopts an four coordination geometry, timb and cyclohexane-1,3,5-tricarboxylate ligands bridge neighboring CuII centers to result in two different one-dimensional knotted chains along the [0 − 1 2] and [1 0 − 1] directions, respectively. The two kinds of chains intersect each other vis CuII centers, resulting in a two-dimensional layered structure running parallel to the (1 2 1) plane. Adjacent layers are further linked by water moleculars via classical O–H…O hydrogen-bonding interactions, giving rise to a three-dimensional supramolecular network structure in the solid state. While in MOFs (II), the cyclohexane-1,3,5-tricarboxylate anions link the CoII cations to generate a two-dimensional sheeted metal-organic structure running parallel to the bc plane. Adjacent sheets are further bridged by timb ligands, forming a porous three-dimensional metal-organic framework with a rare (3, 4)-connected (6.82)2(62.84)3(62.8)2 topology. The solvent water molecules guest in the micropores of porous framework via water-carboxylate O–H…O hydrogen bonds. In addition, their thermal stabilities have also been investigated.

Highly sensitive and selective sensing of ascorbic acid in water with a three-dimensional terbium(III)-based coordination polymer

Ascorbic acid (AA), an essential nutrient in the human body, is an antioxidant that protects the body from the threat of free radicals. The sensitive, efficient and rapid detection of AA has far-reaching significance in human health, biomedicine and food-related science. Herein, pyromellitic acid (H4btec) and nicotinic acid (Hntca) were used as ligands to synthesize a novel terbium-based coordination polymer ([Tb(Hbtec)(Hntca)(H2O)3]·H2O) under solvothermal conditions, which was interlaced by coordination bonds and hydrogen bonds to form an infinitely extended three-dimensional supramolecular structure. The two ligands as “antenna molecules” could effectively sensitize Tb3+ luminescence. The research results showed that AA was selectively recognized by the complex through significant fluorescence quenching response, and it had excellent detection sensitivity (the detection limit is 0.8 μM) and anti-interference ability. The sensor system was successfully applied to the detection of AA in practical samples, so it was expected to be sensitive and efficient AA sensor. In addition, the sensing mechanism was analyzed in detail by the combination of characterization method and density functional theory (DFT), which was attributed to the absorption competition of excitation light energy and the photoinduced electron transfer (PET) process.

Multifunctional Viologen-Derived Supramolecular Network with Photo/Vapochromic and Proton Conduction Properties.

A supramolecular network [H4bdcbpy(NO3)2·H2O] (H4bdcbpy = 1,1′-Bis(3,5-dicarboxybenzyl)-4,4′-bipyridinium) (1) was prepared by a zwitterionic viologen carboxylate ligand in hydrothermal synthesis conditions. The as-synthesized (1) has been well characterized by means of single-crystal/powder X-ray diffraction, elemental analysis, thermogravimetric analysis and infrared and UV-vis spectroscopy. This compound possesses a three-dimensional supramolecular structure, formed by the hydrogen bond and π–π interaction between the organic ligands. This compound shows photochromic properties under UV light, as well as vapochromic behavior upon exposure to volatile amines and ammonia, in which the electron transfer from electron-rich parts to the electron-deficient viologen unit gives rise to colored radicals. Moreover, the intensive intermolecular H-bonding networks in 1 endows it with a proton conductivity of 1.06 × 10−3 S cm−1 in water at 90 °C.

Structural factors governing starch digestion and glycemic responses and how they can be modified by enzymatic approaches: A review and a guide.

Starch is the most abundant glycemic carbohydrate in the human diet. Consumption of starch-rich food products that elicit high glycemic responses has been linked to the occurrence of noncommunicable diseases such as cardiovascular disease and diabetes mellitus type II. Understanding the structural features that govern starch digestibility is a prerequisite for developing strategies to mitigate any negative health implications it may have. Here, we review the aspects of the fine molecular structure that in native, gelatinized, and gelled/retrograded starch directly impact its digestibility and thus human health. We next provide an informed guidance for lowering its digestibility by using specific enzymes tailoring its molecular and three-dimensional supramolecular structure. We finally discuss in vivo studies of the glycemic responses to enzymatically modified starches and relevant food applications. Overall, structure-digestibility relationships provide opportunities for targeted modification of starch during food production and improving the nutritional profile of starchy foods.

A highly sensitive and multi-responsive Tb-MOF fluorescent sensor for the detection of Pb2+, Cr2O72−, B4O72−, aniline, nitrobenzene and cefixime

A terbium metal organic framework (Tb-MOF), namely {[Tb(dppa)(H2O)2]·dima·H2O·0.5O}n (1), (H4dppa = 5-(3′4′-dicarboxylphenoxy)isophthalic acid, dima = dimethylamine, which is formed by the decomposition of DMF in aqueous solution at high temperature.) was prepared and characterized. Tb-MOF is connected by (dppa)4- ligands via μ4:η1,η2,η2,η2 coordination mode to form a two-dimensional wavy network, which is extended to three-dimensional supramolecular structures based on hydrogen bonding. Tb-MOF has excellent fluorescence properties, which can be used for fluorescence recognition and quantitative determination of cation and anion, antibiotics and small organic molecules in aqueous solution with high sensitivity and good selectivity. Tb-MOF showed enhanced fluorescene for Pb2+ and B4O72− ions, while quenching fluorescence for Cr2O72− ion. Noticeably, this is the first time that Pb2+ and B4O72− ions have been detected by a MOF-based fluorescence sensor using a fluorescence enhancement mechanism. More interestingly, Tb-MOF can quantitatively detect aniline (ANI) in aqueous solution by ratiometric fluorescence sensing. In addition, Tb-MOF has great selectivity and sensitivity for detecting of nitrobenzene (NB) and cefixime (CEF). In particular, when NB concentration is 50 μM, the fluorescence quenching rate of Tb-MOF reaches 99.6%. Therefore, this paper introduces a highly sensitive and multi-responsive Tb-MOF sensor, which can be used to detect Pb2+, B4O72−, Cr2O72−, ANI, NB and CEF with fast response speed and good selectivity.

A stable lanthanum-based metal-organic framework as fluorescent sensor for detecting TNP and Fe3+ with hyper-sensitivity and ultra-selectivity

A new Lanthanum-based luminescent metal–organic framework, {[La(H2O)4(HL)]·H2O} (1), has been successfully synthesized by employing 3,3′,5,5′-azodioxybenzenetetracarboxylic acid (H4L) as a rigid organic linker through the solvothermal reactions. 1 exhibits a two-dimensional (2D) layered structure and a three-dimensional (3D) supramolecular structure is formed by hydrogen bonds between the layers. Stability studies indicate that 1 has good chemical stability and thermostability. Meanwhile, the Ksv values for TNP is 4.61 × 104 M−1 with the LOD of 4.13 × 10-6 M and the Ksv value for Fe3+ is 1.22 × 104 M−1 with the LOD of 1.72 × 10-5 M, respectively, which demonstrated that 1 exhibits high sensitivity and excellent selectivity for the detection of TNP and Fe3+via fluorescence quenching. Significantly, 1 shows high regenerability after five recycling progress for sensing Fe3+. The possible mechanisms associated with the luminescent quenching are discussed in detail through some relevant experiments and tests, as well as the DFT calculations. Based on the above excellent properties of 1, it will have extremely potential to be used as a dual functional sensor for both detecting TNP and Fe3+ in aqueous solution, simultaneously.

Highly selective and turn-on fluorescence probe with red shift emission for naked-eye detecting Al3+ and Ga3+ based on metal-organic framework

A novel ZnII-based metal-organic framework with the formula of {[Zn2(BBIP)2(NDC)2]·H2O}n (JXUST-5) derived from 3,5-bis(benzimidazol-1-yl)pyridine (BBIP) and 1,4-naphthalenedicarboxylic acid (H2NDC) has been synthesized. The adjacent ZnII ions are linked through two BBIP ligands to form a [Zn2(BBIP)2] secondary building unit (SBU). The neighbouring SBUs are further connected by NDC2− with μ2-η1:η1 and μ2-η1:η1:η1 bridging modes to form a two-dimensional (2D) framework. Topological analysis shows that JXUST-5 could be simplified as an uninodal fes topology with a point symbol of {4.82}. Furthermore, the 2D framework net could be extended through C-H···π interaction to form the three-dimensional supramolecular structure. Luminescent experiments suggest that JXUST-5 could selectively and sensitively recognize Al3+ and Ga3+ through fluorescence enhancement effect along with a relatively large red shift. The detection limits for Al3+ and Ga3+ are 0.17 and 0.69 ppm, respectively. Interestingly, the sensing process for both Al3+ and Ga3+ could be directly observed with naked eyes under 365 nm UV lamp. Notably, JXUST-5 could be recycled at least five times as a fluorescent sensor toward Al3+ and Ga3+, which is the second example of turn-on MOF based fluorescent sensor toward Ga3+.

Two functional hybrids based on polyoxometalate coordination polymers: Synthesis, electrochemical and photocatalytic properties

Two isostructural polyoxometalate (POM)-based supramolecules were obtained under hydrothermal conditions by the self-assembly of wells–dawson polyoxometalates, transition metal ions and flexible bi(triazole) ligands, namely, [M(H2O)2(btp)(Hbtp)2][H2P2W18O62] (M = Cd for 1, Zn for 2), where the btp represents 1,3-bis(1,2,4-triazol-1-y1)propane). 1 and 2 exhibit three-dimensional supramolecular structures through the hydrogen-bonding reactions. Otherwise, the crystal structures were characterized by single X-ray diffractions, powder X-ray diffraction (PXRD), Thermal Gravimetric curves (TG), Ultraviolet–visible (UV–vis) spectroscopy and Infrared Radiation (IR) spectra. Meantime, the photocatalytic and electrochemical properties were also investigated. 1 and 2 exhibit selectively degredation for cationic dyes of methylene blue (MB) and rhodamine B (RhB). The corresponding degradation efficiency can reach 98% and 34% in an hour. Whereas, no remarkably degradation phenomenon was observed for anionic dye of alphazurine A (ATBA), which may be the electrostatic repulsion between P2W18 and ATBA.

A family of salamo-type trinuclear Co(II) and Ni(II) complexes: Structural characterization, Hirshfeld surface analysis and fluorescent properties

Three trinuclear complexes, [{CoL(MeOH)(μ-OAc)}2Co] (1), [{CoL(EtOH)(μ-OAc)}2Co]·2CH3CH2OH (2) and [{NiL(MeOH)(μ-OAc)}2Ni]·2CH3OH (3) have been successfully synthesized by wet-chemical method using asymmetric salamo-based polydentate chelating ligand (H2L) with transition metal(II) acetate (Co(OAc)2·4H2O or Ni(OAc)2·4H2O). The ligand H2L with N2O2 coordination cavity can accommodate transition metals, at the same time, the oxygen atoms of the phenolic hydroxyl groups can bridge the metal atoms to obtain muiltnuclear metal complexes. There are inversion centers in complexes 1–3 and all M(II) atoms possess six-coordinated distorted octahedral geometries. Complexes 1 and 3 are further assembled into extended two-dimensional supramolecular via intermolecular interactions, but complex 2 forms three-dimensional supramolecular structure. The interactions were quantitatively determined by Hirshfeld surfaces analyses. Significantly, complexes 1–3 have been characterized by elemental analyses, IR spectra, UV–Vis spectroscopy and X-ray crystallography analyses. Fluorescence properties were also investigated.

Synthesis, crystal structure, the Hirshfeld surface analysis, and antimicrobial activity of a three-dimensional Cu(II) complex with N-substituted biguanide

A new antibacterial complex C4H15CuN5O7S, which is derived from the non-insulin-dependent diabetes mellitus drug metformin hydrochloride (MH) and cupric sulfate pentahydrate, is prepared and characterized. The complex shows that a three-dimensional supramolecular structure and the intermolecular interactions are analyzed by the Hirshfeld surface analysis. More importantly, compared with the MH free ligand, the present complex shows excellent antimicrobial activity, especially for Gram-negative bacteria.

Synthesis, crystal structure and highly sensitive detection property of a fluorescent copper coordination polymer

A new luminescent metal-organic framework [Cu(Hbcb)(PYTPY)] (1) (H3bcb=3,5-bis((5′-carboxylbenzyl)oxy)benzoic acid, PYTPY=4′-(4-pyridyl)-2,2′:6′,2′'-terpyridine) has been successfully synthesized and structurally characterized by elemental analysis, IR and single crystal X-ray diffraction. Analysis revealed that an infinite one-dimensional ladder chain was created by offset face-to-face π-π stacking interactions between H3bcb and PYTPY. And it exhibits a three-dimensional supramolecular structure through the π-π stacking interactions between chains. The thermal stabilities and gas adsorption properties of complex 1 was studied. The experimental results show that complex 1 has good thermal stabilities and selective adsorption properties for CO2. The solid-state luminescent properties of MOFs have been measured carefully by ultraviolet irradiation at room temperature. Most noteworthy, complex 1 exhibits a high sensitivity for Fe3+ and nitrobenzene in ethanol solution with mixed metal ions and aromatic compounds, which makes it be a promising crystalline material as luminescent probe to Fe3+ and nitrobenzene. Importantly, complex 1 can keep its original framework and be reused in sensing experiments. The sensing mechanism has also been studied in detail.

Manganese(II) β-Diketonate Complexes with Pyridin-4-one, 3-Hydroxypyridin-2-one and 1-Fluoropyridine Ligands: Molecular Structures and Hydrogen-bonded Networks

Manganese(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionate) complexes with pyridin-4-one (pyon), 3-hydroxypyridin-2-one (hpyon), 1-fluoropyridine (pyF) and methanol were prepared and the solid-state structures were determined by single-crystal X-ray analysis. The coordination of the metal center in all complexes was found to be octahedral. In compounds [Mn(tfpb)2(pyon)2] (1) and [Mn(tfpb)2(hpyon)2] (2) extended hydrogen bonding is present facilitating the formation of a three-dimensional supramolecular structure in 1 and a layered structure in 2 through N-H···O hydrogen bonding enhanced by C-H···O interactions as well as C-F···π interactions. In [Mn(tfpb)2(pyF)2] (3) a layered structure is formed through C-H···O and C-H···F interactions as well as π···π and C-F···π interactions. In [Mn(tfpb)2(MeOH)2] (4) a layered structure is formed through a combination of O-H···O and C-F···π interactions.

Solid state and solubility study of a potential anticancer drug-drug molecular salt of diclofenac and metformin

To improve the physicochemical properties of diclofenac (DFA) and exert its potential anti-tumor effect in combined pharmacotherapy of metformin (MET), a new drug-drug molecular salt of DFA and MET (DFA-MET) is formed and characterized. The single-crystal X-ray diffraction analysis shows that DFA-MET is a three-dimensional (3D) supramolecular structure constructed by different hydrogen-bonding interactions between DFA and MET with 1:1 stoichiometry by proton transfer reaction. In addition, Hirshfeld Surface analysis shows that both the hydrogen-bonding interactions and the Vander Waals maintain the 3D supramolecular structure of DFA-MET together. Compared with pure DFA and pure diclofenac sodium (NaDFA), the dissolving behavior and permeability of DFA-MET by forming drug-drug molecular salt in physiological pH environments are enhanced remarkably.

“SOFT–HARD” STRATEGY TO CONSTRUCT A PYRAZINE SULFONIC ACID COPPER(II) SUPRAMOLECULAR STRUCTURE AND A STUDY OF ITS FLUORESCENT PROPERTY

The design and synthesis of functional heterocyclic sulfonic acid polymers would provide much help in studying the coordination behavior, structural optimization, and application of the polymers. In this work, a three-dimensional (3D) supramolecular structure [Na2Cu(P–SO3)4]n (P–SO3H = pyrazine sulfonic acid) is synthesized by a hydrothermal method with the “soft–hard” strategy. The produced polymer is characterized by the elemental analysis, IR spectroscopy, and X-ray crystallography. Crystal diffraction data indicate that the polymer belongs to the P4/ncc space group. Notably, the introduction of a soft alkali metal ion can trigger the specific affinity binding with sulfonate oxygen atoms to give rise to a Na–O-μ4 bridging pattern. The flexible bridging pattern combined with the rigid structure of copper pyrazine sulfonate is likely to be responsible for the production of the final 3D supramolecular structure. Moreover, powder X-ray diffraction data indicated a good phase purity. Thermal stability, Raman features as well as solid-state fluorescent properties are also investigated in detail.

Exploring coordination behaviors, structural characterizations and theoretical calculations of structurally different Cu(II), Co(II) and Ni(II) emissive complexes constructed from a salamo-based ligand and 4,4′-bipy

A new salamo-based ligand H2L was designed and synthesized, and its structurally different Cu(II), Co(II) and Ni(II) complexes based on ancillary ligand 4,4′-bipy were obtained. The Cu(II) complex has a mononuclear structure with the molecular formula of [Cu(L)], while the Cu(II) ion adopts a twisted four-coordinate quadrilateral geometric configuration. One dimensional chain-like supramolecular structure is formed by intermolecular interactions. In the Co(II) complex, there is a dimer structure and the molecular formula is [Co2(L)2(4,4′-bipy)]. The Co(II) ions possess five-coordinated trigonometric bipyramid geometric configurations. A two-dimensional layered supramolecular structure is formed by intermolecular interactions. The Ni(II) complex has a one-dimensional polymer structure and its molecular formula is [Ni(L)(4,4′-bipy)]n·nEtOH·nAce. The Ni(II) ions have six-coordinated octahedron geometric configurations. Through the intermolecular interactions, a three-dimensional supramolecular structure is formed. The ligand H2L and its three complexes were studied in detail by IR, UV–Vis and emissive spectra. The short-range interactions in the Cu(II), Co(II) and Ni(II) complexes were calculated by Hirshfeld surfaces analyses. The molecular orbital energy levels and molecular stability were analyzed by DFT calculations.

«Soft—hard» strategy to construct a pyrazine sulfonic acid copper(II) supramolecular structure and a study of its fluorescent property

The design and synthesis of functional heterocyclic sulfonic acid polymers would provide much help in studying the coordination behavior, structural optimization, and application of the polymers. In this work, a three-dimensional (3D) supramolecular structure [Na2Cu(P—SO3)4]n (P—SO3H = pyrazine sulfonic acid) is synthesized by a hydrothermal method with the «soft—hard» strategy. The produced polymer is characterized by the elemental analysis, IR spectroscopy, and X-ray crystallography. Crystal diffraction data indicate that the polymer belongs to the P4/ncc space group. Notably, the introduction of a soft alkali metal ion can trigger the specific affinity binding with sulfonate oxygen atoms to give rise to a Na—O-μ4 bridging pattern. The flexible bridging pattern combined with the rigid structure of copper pyrazine sulfonate is likely to be responsible for the production of the final 3D supramolecular structure. Moreover, powder X-ray diffraction data indicated a good phase purity. Thermal stability, Raman features as well as solid-state fluorescent properties are also investigated in detail.

A three-dimensional supramolecular network structure through hydrogen bonding and π–π interaction: synthesis, structure, and the fluorescence detection of balsalazide disodium

Three co-crystal compounds with different dimensions were synthesized. The fluorescence properties of co-crystal 1 were studied, especially detecting balsalazide disodium.