1D Polymeric Structure Research Articles

3-Nitramino-6-hydroxy-1,2,4,5-tetrazine and its alkaline earth metal salts: an effective strategy to balance energy density and safety of energetic compounds

ABSTRACT 3-Nitramino-6-hydroxy-1,2,4,5-tetrazine (NHTZ) and its alkaline earth metal salts (Mg2+(1), Ca2+(2), Sr2+(3), Ba2+(4)) were prepared via 3,6-dinitramino-1,2,4,5-tetrazine for the first time. The electrostatic potentials and HOMO-LUMO orbitals of them were computed to better understand the electronic structure of NHTZ. Structures of the four alkaline earth metal salts were confirmed by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that all compounds have differently dimensional structures, increasing with the radius of metal atoms. Compounds 3 and 4 can be classified as coordination polymers due to their structural features. As the only 3D polymeric structure in this series, compound 4 possesses the highest density and best thermal stability in these compounds. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurement shows the excellent thermal stability of these salts, with the thermal decomposition temperatures of 291.1°C (1), 294.1°C (2), 294.9°C (3) and 324.7°C (4). Heat of formation and sensitivity of the four salts were investigated, which suggest 4 as a potential heat-resistant energetic compound instructions for authors.

A 3D Synthesis Strategy for Pyrene-Based Fluorescent Conjugated Polymers and Application in Picric Acid Sensing

In this work, 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) was synthesized and used as polymer precursor, and then two kinds of fluorescent conjugated polymers (CPs) are synthesized through Schiff base reactions with two kinds of tri-amine as the other part of precursor, namely CPshu-1 and CPshu-2, respectively. By using D2h symmetry tetra-aldehyde and C3 symmetry tri-amine as precursors, aggregation-caused quenching (ACQ) of fluorophore can be reduced to minimum, to make the greatest fluorescent sensing performance. The resulting CPs were firstly characterized by Fourier transform infrared spectroscopy (FT-IR), solid-state 13C nuclear magnetic resonance (13C NMR). The morphology of resulting CPs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fluorescent spectra indicated that the sample showed orange luminescene at around 610nm. Before detecting the sensing performance, the CPs were firstly dispersed into acetonitrile to make a 1 mg/mL suspension, and the suspension showed a high sensitive to picric acid (PA). The suspension of CPshu-1 was totally quenched at a PA concentration of 5.2×10-4 M, and the limit of detection was calculated to be 3.18 ppm. For CPshu-2, the suspension was totally quenched at a PA concentration of 3.5×10-4 M, and the limit of detection was calculated to be 2.11 ppm. This work demonstrated that we can design 3D polymer structure to avoid ACQ negative effects, and build high performance fluorescent chemosensing materials. Introduction Fluorescent chemosensors is a kind of sensors which is attracting increasing attention from scientists. Aromatic π-electron conjugated polymers(CPs) is a very important kind of organic polymers used as fluorescent chemosensors due to the advantages of signal amplification, ease of device fabrication and the ability to combine different outputs. Although there has been a fast progress in the development of fluorescent CPs, there are still great requirements on materials with high efficiency, low cost, and eco-friendly, and also the design strategy of building CPs should also be developed. Making use of AIE and ACQ phenomena can rationally and tactfully enhance the fluorescene performance and avoid unexpected quenching, resulting in increasing importance for design strategy of fluorescent CPs.In this study 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) was used as fluorophore to build CPs through Schiff base reaction. The monomer of TFPPy was synthesized through a Suzuki coupling according to literature with a modified solvent condition. Two kinds of CPs named as CPshu-1 and CPshu-2, respectively, have been grown by solvothermal method using TFPPy as aldehyde monomer. The structures of both CPs were designed as 3D structure in which π-π stacking of fluorophores were avoided, decreasing the ACQ phenomenon to the minimum. The formation of CPs from the condensation reactions of the monomers was supported by FT-IR and 13C NMR spectra. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated the rod-like morphology of resulting CPs, which could also prove the non-stacking structure of aromatic fluorophores. Furthermore the CPs were dispersed into acetonitrile and the suspension was used to detect picric acid. Both suspensions of CPshu-1 and CPshu-2 showed great chemical sensitive to picric acid, and the limit of detection (LOD) was 3.18ppm for CPshu-1, and 2.11ppm for CPshu-2, respectively. Figure 1

A 2D coordination polymer assembled from a nickel(II) tetraazamacrocyclic cation and 4,4'-(dimethylsilanediyl)diphthalate(3-) linker.

The preformed nickel(II) complex of the 14-membered macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane (cyclam, L), when treated with 4,4'-(dimethylsilanediyl)diphthalic acid (H4A) in a DMF/H2O mixture (4:1 v/v) under heating, leads to [Ni(L)]3(HA)2·3DMF (I·DMF). Redissolution of this compound in a DMF/H2O/MeOH mixture (4:1:30 v/v/v) with mild acidification under gentle heating results in the formation of a similar compound but containing water and methanol molecules of crystallization, [Ni(L)]3(HA)2·5H2O·2MeOH (II·H2O). At lower temperature and concentration of reactants and longer reaction time, single crystals of composition {[{Ni(L)}3(HA)2]·4CH3OH}n (II·MeOH) were isolated. Single-crystal X-ray diffraction analysis of this compound, which, according to PXRD is isostructural with II·H2O but different from I·DMF, revealed its two-dimensional (2D) polymeric structure, i.e. poly[[bis{μ3-4-[(4-carboxy-3-carboxylatophenyl)dimethylsilyl]benzene-1,2-dicarboxylato-κ3O1:O2:O3'}tris(1,4,8,11-tetraazacyclotetradecane-κ4N)trinickel(II)] methanol tetrasolvate], {[Ni3(C18H13O8Si)2(C10H24N4)3]·4CH3OH}n. It is built up of the monoprotonated tricarboxylate HA3- ligand coordinated in a monodentate manner in the axial positions of two crystallographically independent NiII cations, one of which is located on a crystallographic inversion centre. Both metal ions adopt a slightly tetragonally elongated trans-N4O2 octahedral geometry. The compound has a lamellar structure with polymeric layers oriented parallel to the (10-2) plane, which are in turn linked via hydrogen bonds involving protonated carboxylic acid groups of the ligand. Bulk compounds I·DMF and II·H2O were characterized by FT-IR and diffuse reflectance spectroscopy and thermogravimetry, which provide evidence of their structural differences.

Selective Detection of Folic Acid Using 3D Polymeric Structures of 3-Carboxylic Polypyrrole.

The detection of folic acid in biological samples or pharmaceutical products is of great importance due to its implications in the biological functions of the human body, along with the development and growth of the fetus. The deficiency of folic acid can be reversed by the intake of different pharmaceutical formulations or alimentary products fortified with this molecule. The elaboration of sensing platforms represents a continuous work in progress, a task in which the use of conductive polymers modified with different functionalities represents one of the outcoming strategies. The possibility of manipulating their morphology with the use of templates or surfactants represents another advantage. A sensing platform based on carboxylic functionalized polypyrrole was synthesized via the electrochemical approach in the presence of a polymeric surfactant on a graphite-based surface. The sensor was able to detect the folic acid from 2.5 μM to 200 μM with a calculated limited of detection of 0.8 μM. It was employed for the detection of the analyte from commercial human serum and pharmaceutical products with excellent recovery rates. The results were double checked using an optimized spectrophotometric procedure that confirmed furthermore the performances of the sensor related to real samples assessment.

Synthesis and Crystal Structures of Alkali and Alkaline Earth Metal Complexes of 3,5‐Dinitropyrazolyl‐4‐carboxylate

The synthesis and crystal structures of 3,5‐dinitro‐1H‐pyrazolyl‐4‐carboxylic acid (H2dnpzc) and its four complexes with Ca2+, Ba2+, Na+ and K+ are reported in this paper. Ca(dnpzc)·5H2O exhibits a 1D polymeric structure, whereas Ba(dnpzc)·4H2O possesses a 2D structure. The structure of Na2(dnpzc)·4H2O consists of 2D layers of [Na(dnpzc)]–n and 1D chains of [Na(H2O)3]+n. K2(dnpzc)·H2O has a true 3D structure. It was observed that the doubly deprotonated ligand (dnpzc2–) can act as a versatile bridge to form polymeric structures by varying combinations of its 8 potential donor atoms (two carboxy O atoms, two pyrazolyl N atoms and four nitro O atoms). Particularly in the structure of K2(dnpzc)·H2O, all the 8 donor atoms of dnpzc2– take part in the coordination and as many as 10 potassium atoms are connected by one ligand.

From solid state to in vitro anticancer activity of copper(II) compounds with electronically-modulated NNO Schiff base ligands.

The copper(ii) complexes of general formula [Cu(GL)(Cl)] (1-3, G = OMe, H and NO2, respectively), bearing tridentate Schiff base ligands (GL-) and a chloride as a fourth labile one, are here reported. The Schiff bases derive from the monocondensation of ethylenediamine and substituted salicylaldehyde, where the electronic properties are modulated by the releasing or withdrawing power of the G group. The compounds were structurally characterized through single crystal Synchrotron X-ray diffraction experiments in the solid state, revealing that 1 (OMe) and 2 (H) adopt a dimeric assembly [Cu(μ-Cl)(GL)]2 through apical interaction of the chloride ions of two monomeric units, while 3 embraces a 1D polymeric chain structure [Cu(μ-Cl)(NO2L)]n with a similar bridging fashion, all supported by extended intramolecular or intrachain hydrogen bonds. The redox properties of the complexes were also studied by cyclic voltammetry with no marked effect of the substituent on the potential of the CuII/CuI redox system. UV/Vis spectroscopic studies in mimicked physiological conditions highlighted the intactness and stability of the coordinated NNO tridentate ligand in 1-3 and the lability of the coordinated chloride ion with the formation of the aquo-complexes [Cu(GL)(H2O)]+ in aqueous solution, as confirmed by conductance measurements with a 1 : 1 electrolyte molar conductivity. In vitro tests on cell viability were conducted on malignant cell lines typical for their poor prognosis and curability, revealing time-dependent and differential cytotoxicity given by the substituent G. All compounds were capable of formation of intracellular reactive oxygen species and DNA intercalation, acting as nuclease and producing double-strand DNA breaks. This is especially effective for 3 (NO2), which revealed the highest anticancer activity against malignant triple-negative breast cancer MDA-MB-231 cells, with a two-to-four-fold cytotoxicity enhancement with respect to 1 (OMe) and 2 (H), and, most important, substantial differentiation of cytotoxicity with respect to healthy endothelial HUVEC cell line.

Structure and synthesis of copper-based Schiff base and reduced Schiff base complexes: a combined experimental and theoretical investigation of biomimetic catalytic activity.

Three copper(ii) complexes, [Cu(L1)(NCS)]n (1), [Cu(L1)(N3)]n (2) and [Cu(L2)(N3)] (3) were synthesized from one Schiff base ligand and one reduced Schiff base ligand, (E)-4-chloro-2-[(2-propylaminoethylimino)methyl]phenol (HL1) and 4-chloro-2-[(2-(propylaminoethylamino) methyl]phenol (HL2), respectively. All complexes were characterized by various physicochemical studies, such as FT-IR, UV-Vis, ESI-MS, EPR and single crystal X-ray diffraction. Complexes 1 and 2 have 1D polymeric chain-like structures bridging through thiocyanate and azide anions, whereas complex 3 has a mononuclear structure in the solid state. All the complexes are active towards mimicking two well-known proteins, phosphatase and phenoxazinone synthase, using the disodium salt of 4-nitrophenylphosphate (4-NPP) and 2-aminophenol (OAP) as the substrate in DMF medium. Complexes 2 and 3 show the highest activity towards phosphatase and phenoxazinone synthase activity with kcat values of 22.6 s-1 and 134.4 h-1, respectively. EPR studies confirmed that for complex 1, the OAP oxidation goes through the generation of an organic radical at g = 1.99, which is due to an imine radical formation, whereas the metal center redox pathway is followed for complex 3. Extensive DFT calculations have been performed for both catalytic studies to put forward the most probable mechanistic pathways.

Bisulfone-Functionalized Organic Polymer Photocatalysts for High-Performance Hydrogen Evolution.

Conjugated polymers show great potential in the application of photocatalysis, particularly for the photoreduction reaction of water to generate hydrogen. Molecular structure design is a key part for building a high-performance organic photocatalyst. Herein, two bisulfone-containing conjugated polymer photocatalysts were constructed with 1D or 3D polymer structures, and the effect of polymer geometry on photocatalytic activity was studied. It was found that the linear polymer PySEO-1 exhibited increased photocatalytic performance compared with the 3D polymer network PySEO-2 because the enhanced coplanarity of the polymeric chain in PySEO-1 promoted the photogenerated charge-carrier transmission along the 1D main chain. As a result, an attractive hydrogen generation rate of 9477 μmol h-1 g-1 was obtained with PySEO-1 under broadband light irradiation. PySEO-1 also exhibited a high external quantum efficiency of 4.1 % at an incident light wavelength of 400 nm, demonstrating that the bisulfone-containing polymers are attractive as organic photocatalysts for hydrogen production.

Cadmium coordination compounds with flexible ligand 1,3-bis(1,2,4-triazol-1-yl)propane: Synthesis, structure and luminescent properties

Six new cadmium coordination compounds with flexible 1,3-bis(1,2,4-triazol-1-yl)propane (btrp) ligand, [Cd(btrp)(H2O)2(NO3)2]n (1), [Cd(btrp)2(NO3)2]·H2O (2), [Cd(btrp)Hal2] (3–5) (Hal = Cl, Br, I) and [Cd2(btrp)2(DMF)2(μ2-Br)2Br2] (6) were synthesized. The crystal structures of the complexes 1 and 6 were determined. 1 has 1D polymeric structure while 6 is binuclear. The latter reveals rare gauche–gauche conformation of btrp ligand. Luminescent properties of 1–6 in the solid state were studied in comparison with free btrp. The emission of the compounds corresponds to intraligand transitions, while the bands exhibit complicated shape that can be described by two Gauss functions.

Characterization and Thermal Behavior of the Iron Dietary Supplement Ferrous Glycine Sulfate Pentahydrate

Ferrous glycine sulfate pentahydrate [Fe(glycine)(SO4)·5H2O with glycine = C2H5NO2], contained in the supplement for treating iron deficiency anaemia, commercially known as ferro sanol duodenal®, was characterized by laboratory X‐ray powder diffraction (XRPD), scanning electron microscope (SEM), and infrared spectroscopy (IR). The thermal behavior was investigated by thermal analysis (TGA and DTA) and temperature‐dependent in situ XRPD measurements. Furthermore, the phase transitions to a less hydrated form [Fe(glycine)(SO4)·3H2O] and successively to the anhydrous form were demonstrated to occur in the crystalline solid state. Compared to the crystal structure of the pentahydrate, the trihydrate exhibits a different coordination environment of the iron sites where glycine ligands bridge iron forming a 1D polymeric chain structure. From detailed structural comparison, the mechanism of the phase transitions can be concluded.

Uso de las nuevas tecnologías para estimar la calidad de vida en lactantes con enfermedades infecciosas prevenibles o potencialmente prevenibles mediante vacunación

A hierarchical structure featuring both nano- and macro- structure has emerged as prospective candidates for the application requiring high flow rates and specific surface area. A unique physical and mechanical behavior could be discovered by designing a special structure. A random orientated nanoporous copper thin film coated on a three-dimensional (3D) microporous periodical octet-truss lattice was utilized as a hierarchical structure to evaluate the mechanical and catalytic behaviors. Nanoporous copper films with ligament size ranging from 16 to 28 nm were synthesized using magnetron co-sputtering CuAl alloy films and subsequent dealloying process, while the octet-truss with a pore size of 120 μm was fabricated by digital light processing. The yield strengths of the octet-truss lattice with nanoporous Cu (L-NPC) films are 3 times higher than those of low-density bulk Cu or Cu films predicted by the Gibson-Ashby equation. The current densities and electrochemical surface area of the l-NPC films are also 10 times higher than those of octet-truss lattice with solid Cu films or NPC films coating on a two-dimensional substrate. In addition to the nano-scale pore size effect, the 3D polymer structure produced a high curly surface for NPC films to attach on the truss which could be the reason for the different mechanical and electrochemical behaviors.

Plastically Deformable and Exfoliating Molecular Crystals of a 2-D Coordination Polymer and Its Ligand

4-n-Hexyloxybenzoic acid and the corresponding potassium salt were synthesized and crystallized, and their force-induced mechanical response was studied. 4-n-Hexyloxybenzoic acid is crystallized as large single crystals of the reported monoclinic polymorph, whereas, its potassium salt forms a 2D polymeric structure. When a localized mechanical force is applied, crystals of both materials undergo plastic deformation to the extent that they can be folded to resemble characters of the English alphabet. With few cycles of bending and unbending, the crystals can be exfoliated, and crystalline layers can be separated. In both structures, van der Waals interactions of the hexyl chains contribute toward the formation of slip plane parallel to the wider face of the crystals, which is necessary for their plastic deformability. Reported crystal structures of 4-n-alkoxybenzoic acids with alkyl chain length ranging from C1 to C10 and their inorganic salts were analyzed, and it was found that packing of alkyl chains su...

Three isomers in a (hydrogen l-Cysteinato)-thallium(I): Crystal structure, spectroscopic and thermal properties

The isolation of thallium(I) complexes [Tl2(HCys)2]n (1) and [Tl4(HCys)4]n (2) {H2Cys = l-Cysteine} from aqueous solution by means of crystallization is reported herein. Polar crystals of 1 and 2 were crystallized in P21 and P212121 space groups respectively. Elemental analysis, XRD, IR, UV–Vis, TG-DSC and a single crystal X-ray diffraction were applied for characterizing the compounds. Linkage isomers 1 and 2 have 1D and 2D coordination polymeric structures respectively. The lone pair electrons of thallium(I) in 1–2 are stereo-chemically active. In 1, each of two independent Tl+ ions is coordinated by three HCys− ions forming TlS3O irregular polyhedron that is linked to each other by vertexes in an infinite chain. In 2, four independent Tl+ ions are coordinated by HCys− ions through S and O atoms, forming Tl1S3O2, Tl2S4, Tl3S3, Tl4S3 irregular polyhedrons. The crystallographic independent HCys− ions are linked to the metal ion differently, two are μ3-S,S,S-, one is μ4-O,S,S,S-, and one is μ4-O,O',S,S,S-coordinated ligands. The amine group of compounds 1 and 2 is in the form of an ammonium ion (–NH3+). The structures of 1–2 are stabilized by NH⋯O hydrogen bonds, thallophilic Tl⋯Tl and anagostic Tl⋯HC interactions. The spectroscopic and thermal properties of compounds were analyzed.

Silver-based monomer and coordination polymer with organic thiocyanate ligand: Structural, computational and antiproliferative activity study

The first complexes of 2-pyridylthiocyanate (L) and silver nitrate (1) and perchlorate (2) were prepared and characterized by a single crystal X-ray analysis. The common structural motif of both 1 and 2 is coordination of two L molecules via pyridine nitrogen atom to Ag(I). In order to properly describe the nature of coordinative bonds in 1 and 2, as well as crystal packings in respective structures, a Quantum Theory of Atoms in Molecule topological analysis was performed. Coordinated nitrate ion provides more electron density to Ag(I) in comparison to perchlorate ion. Additional electron density in the case of 2 was provided by the coordination of third L molecule via thiocyanate nitrogen atom resulting in a 1D polymeric structure. Detailed computational analysis of intermolecular interactions, as well analysis of interactions between pyridine ring and –SCN group was performed. Antiproliferative activity of monomeric compound 1 was found to be better than of cisplatin on three out of four studied human cancer cell lines. Docking studies indicate intercalation as a major binding mode of 1 to DNA, while human serum albumin was revealed as possible carrier for distribution of 1 in the blood stream.

3-Arm PEG Based Amphiphilic Polymer Sorbents for Polar and Non-Polar Liquids

Crosslinked polymer gels are gaining technological and industrial attention due to their sophisticated application features. Herein, a highly effective amphiphilic polymeric network capable of absorbing polar and nonpolar solvents was produced using hydrophilic glycerol ethoxylate, a member of star type polyethylene glycol (s-PEG), and different hydrophobic organosilane monomers by bulk polymerization as utilized under an inert atmosphere. In this context, the preparation of amphiphilic polymeric networks was achieved by the reaction between hydroxyl terminated s-PEG and ethoxysilane terminated organosilane without using any initiator, activator or a catalyst. SEM, FTIR, 13C and 29Si CPMAS NMR and TGA are used for morphological, structural and thermal characterization of the prepared materials. Likewise, the absorption behavior of amphiphilic polymeric networks was determined by measuring their swelling ratios in polar and nonpolar solvents. Because of having a hydrophobic and hydrophilic structure in their 3D polymeric structure, the obtained polymeric networks behave as an organogel in oil medium, while they can prepared as a hydrogel in aqueous medium. The effect of crosslinker’s difference on the swelling capacity of sorbent were researched by comparing different molecular weight of monomers, and it was found that the molecular structure of organosilane monomers had significant influence on the swelling ability of obtained amphiphilic sorbents. By the use of easy preparations, not needing extra agents for the synthesis, having high and quick absorption abilities in organic solvents showed that the resulting amphiphilic sorbent have potential as absorbents for different organic solvents. Also, the degradable features of amphiphilic polymer networks in water open up optimum application opportunities for additional uses, such as with drug delivery agents.

Plug-and-play fiber to waveguide connector.

The mass production and commercialization of integrated photonics have been slowed down by the high cost of packaging its optical interfaces. We show a plug-and-play connector between a fiber and a nanophotonic waveguide consisting of a 3D polymer structure with a fiber entrance port that simultaneously achieves mechanical and optical passive alignment with tolerance beyond ±10 μm to the fiber input position. We take advantage of a mechanical and optical co-design, analogous to commercial fiber-to-fiber connectors. We fabricate the plug-and-play couplers using 3D nanoprinting directly on foundry fabricated diffraction grating couplers. We measure an average of only 0.05 dB excess coupling loss between a single mode fiber and a high confinement silicon waveguide in addition to the inherent grating coupler loss. Our coupling platform offers a passive plug-and-play solution for scalable integrated photonics fiber-chip packaging.

Lanthanide coordination polymers based on flexible ligands derived from iminodiacetic acid

Two flexible ligands derived from iminodiacetic acid, N-methlyiminodiacetic acid (H2mida) and N-(2-hydroxyethyl)iminodiacetic acid (H2hida) have been used as ligands towards lanthanide ions. Potentiometric studies (25.0 °C, 0.50 mol L−1 Me4NCl) revealed the predominance of stable species at acidic pH values. With this information, the synthesis of the coordination compounds was afforded in aqueous solution and the polymeric solids [Sm(Hmida)2(H2O)2]ClO4·1/6NaClO4·9H2O and [Ln(hida)(H2O)2](F3CSO3)·H2O (Ln = Ho, Yb) were prepared and characterized. The samarium compound consists of a cationic 2D polymeric structure in which the ligand is protonated in the N atom, preventing coordination to the central atom. The structure presents channels along one crystallographic direction. Ho and Yb coordination compounds are isostructural. A 2D polymeric cationic network is also observed. In this case, the additional hydroxyethyl group and the unprotonated N atom participate in the coordination.

Methods for Synthesis of Molecular Materials with Unique Physical Properties

The authors discovered and investigated new types of stable heterometallic carboxylate complexes in which divalent transition metal atoms of the 4th period of the Periodic Table of Chemical Elements (V, Co, Ni, Cu, Zn) combine with atoms of lithium, magnesium, calcium or rare earth elements. These polynuclear heterometallic compounds retain their structure under conditions when the homometallic compounds of these transition metals decompose to mononuclear complexes. The different metals combination in one molecule allows us to use the obtained heterometallic compounds for producing disperse and film oxide materials, and bimetallic oxide catalysts. The stability of the complexes allows to immobilize them in various matrices and to assemble 3D polymer structures on their base. Since the metal ions under consideration (V, Co, Ni, Cu, Zn) are capable to form isostructural heterometallic compounds, it becomes possible to obtain compounds within a single structural type with a given combination of physical properties, determined by the nature of the metal ions.

The influence of co-anions on the structural dimension of mercury (II) coordination polymers: Synthesis, crystal structure, spectroscopy and biological activity investigations

Two new mercury (II) polymeric complexes namely, [Hg2(µ-bbit)Cl4]n (1) and [Hg(µ-bbit)(SeCN)2]n (2) [bbit = 1,1-(1,4-butanediyl)bis(1,3-dihydro-3-methyl-1H-imidazole-2-thione] have been successfully synthesized and characterized by the single crystal X-ray diffraction analysis, IR, CHNS, PXRD and TGA. X-ray analysis shows that reaction of the bbit ligand with HgCl2 leads to the formation of 2D honeycomb coordination polymer of 1. Polymer 2 with an unpresented 1D wave-like structure was prepared by addition of selenocyanate to the reaction mixture of polymer 1. In both complexes, the coordination geometry about each mercury atom can best be described as trigonal pyramidal with core structures of HgCl3S (for 1) and HgSe2S2 (for 2) and the bbit ligands adopt a bridging mode through two sulfur atoms between the mercury atoms. The title polymers are further stabilized by the intermolecular hydrogen bonds to form a 3D polymeric network structure. Their antibacterial and DNA cleavage activities were also evaluated. On the base of the obtained results, these compounds have a broad antibacterial activity against both Gram-positive and Gram-negative species, while the Gram-positive species were more effected with these polymers. It may suggest that the functional groups present in the envelope of these bacteria are the main target for S-donor sites in the considered compounds.

Determination of compressive strength of 3D polymeric lattice structure as template in powder metallurgy

Powder metallurgy has been developed to fabricate metal foams from various materials including magnesium. One particular challenge on powder metallurgy is fabrication of highly-ordered and interconnected porous products. Pores interconnectivity is important in application of porous magnesium alloy for biodegradable orthopedic implants. Meanwhile, 3D polymeric printing technology offers capability to build precise and rapid lattice wireframe products in a simple and low-cost manner. Here, we design and validate the capability of 3D polymeric lattice as template in powder metallurgy for fabrication of magnesium-based biodegradable implants. Lattice structures were made of ABS, PLA, and PVA filaments. Lattice structures were cubical-shaped with uniform dimension and variations in pore size are included in the study. Both computational and experimental tests are performed to determine the compressive strength of the lattice structures. Uniaxial stress with uniform magnitude is applied to test the lattice structures. The resulting stress, strain, and deformation of the 3D polymeric lattice are observed. Variations in materials and pore size affect the stress, strain and deformation of the 3D polymeric lattice. Parameters can be further optimized to meet the requirement of the design and fabrication process in consideration of the tolerable stress, strain and deformation.