Conjugated polymers for the fluorescent detection of nitroaromatics: Influence of side‐chain sterics and π‐system electronics

A series of eight poly(p‐phenylene vinylene) (PPV) and poly(p‐phenylene ethynylene) (PPE) ( P1–P8 ) derivatives were tested for their ability to detect the nitroaromatic explosive 2,4,6‐trinitrotoluene (TNT) and its model compound 2,6‐dinitrotoluene (DNT). The polymers P1–P8 represent five structural classes that have not been examined for nitroaromatic sensing. These new motifs include PPE derivatives with a main‐chain m‐terphenyl unit ( P1 ) or oxacyclophane canopy‐like structure ( P2 ) and PPV derivatives with 2,6‐mesitylenephenylene repeats ( P3 and P4 ), 9,9‐dialkyl‐1,4‐fluorenylene repeats ( P5 and P6 ), or m‐phenylene units that periodically disrupt π‐conjugation along the backbone of the polymer ( P7 and P8 ). The time‐dependent photoluminescent response of films to TNT and DNT and the solution‐phase Stern‐Volmer quenching constants for both TNT and DNT were determined. The results are rationalized in terms of side‐chain sterics and π‐system electronics and are discussed relative to known conjugated polymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1487–1492     

A 2D Cd(II)-MOF as a multifunctional luminescencent sensor for nitroaromatics,iron(III) and chromate ions

A Cd(II)-MOF, {[Cd(L)(4,4′-bipy)]·H₂O·DMF}_n (1) (L = nicotinic acid (2,4-dihydroxybenzylidene)-hydrazide and 4,4′-bipy = 4,4′-bipyridine), has been synthesized and characterized by microanalyses, FTIR, TGA, and single-crystal X-ray diffraction. Additionally, powder X-ray diffraction was performed to check the phase purity of the synthesized compound. Single-crystal X-ray diffraction reveals that 1 has a 2D grid network. Photoluminescent sensing of nitrobenzene, Fe(III) and CrO₄^2? ions indicates that 1 could be a candidate for developing selective luminescent sensors for these species. Theoretical calculations have been performed to gain insight into the possible mechanism of quenching effect in emission on addition of nitrobenzene in 1 which supports the mechanism operating through ground state charge transfer between 1 and nitrobenzene.     

1-亚甲基苯并咪唑-1,4,7-三氮环壬烷配体及其铜配合物[Cu(C14H21N5)Br]2•[CuBr4]的合成与晶体结构

采用新的方法合成了1-亚甲基苯并咪唑-1,4,7-三氮环壬烷配体, 利用该配体合成了一个新的铜配合物[Cu(C₁₄H₂₁N₅)Br]₂•[CuBr₄] ([Cu(C₁₄H₂₁N₅)Br]^＋•[CuBr₄]^2－•[Cu(C₁₄H₂₁N₅)Br]^＋), 并测定了它的晶体结构, 结果表明: 该配合物的晶体属于单斜晶系的C2/c空间群, 晶胞参数a＝1.96209(15) nm, b＝0.82319(5) nm, c＝2.39249(15) nm, α＝90.00°, β＝102.996(2)°, γ＝90.00°, V＝3.7653(4) nm³, Z＝4, μ(Mo Kα)＝8.083 mm^－1, D_c＝2.097 Mg/m³, F(000)＝2308, R＝0.0417, wR＝0.0945, GOF＝0.933. 该配合物由两个1-亚甲基苯并咪唑-1,4,7-三氮环壬烷一溴合铜配阳离子和一个四溴合铜配阴离子组成. 在两个配阳离子中, 每个Cu(II)离子与五个配位原子配位(四个氮原子和一个溴阴离子), 位于一个变形四方锥的中心. 在配阴离子中, Cu(II)离子与四个溴阴离子配位, 位于一个稍变形四面体的中心.     

A pillar-layered Cd(II) metal-organic framework for selective detection of organic explosives

The detection of explosives is crucial for homeland security, environmental cleaning, and military issues. As a new class of porous materials, metal-organic frameworks (MOFs) are promising platforms for the detection of organic explosives. In this work, a new pillar-layered Cd(II) MOF, [CdL_0.5dpe_0.5]·2H₂O (BUT-202, H₄L = 4,8-disulfonaphthalene-2,6-dicarboxylic acid, dpe = 1,2-bis(4-pyridyl)ethylene), was synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and elemental analysis. BUT-202 has good fluorescent properties, which can be selectively quenched by trace amounts of 2,4,6-trinitrophenol (TNP) in DMF with low detection limit of 0.2 μM.     

A fluorescent Cd(II) based 2-D coordination polymer for highly selective detection of nitroaromatics and Hg2+

A 2-D Cd(II) coordination polymer (CP), {[Cd₂(L)₂(4,4′-bipy)₂(H₂O)?7H₂O]_n (1), has been synthesized using 5-aminoisophthalic acid (H₂L) as ligand and 4,4′-bipyridine as co-ligand. A single-crystal X-ray diffraction study shows that 1 is an infinite 2-D layer. CP 1 behaves as a highly selective and sensitive fluorescence chemosensor for detection of Hg²⁺ and 2,4,6-trinitrotoluene (TNT). Furthermore, possible emission quenching in 1 in the presence of nitroaromatics has been addressed with the aid of theoretical calculations. The calculations indicated that there are both electron and energy transfer processes, in addition to electrostatic interaction between 1 and nitroaromatics which contributes to the selective fluorescence quenching.     

Phenylene(vinylene) based fluorescent polymer for selective and sensitive detection of nitro‐explosive picric acid

We report the synthesis of phenylene(vinylene) based blue light emitting polymer by atom transfer radical polymerization with very good yield. Their photophysical properties were studied systematically with increasing polarities of solvent and sensing of nitro aromatics in solution and in vapor phase. The sensory properties of the polymer were studied toward various nitroaromatic compounds like nitrobenzene (NB), nitrotoluene (NT), dinitrobenzene (DNB), dinitrotoluene (DNT), nitro benzoic acid (NBA), 3‐nitro benzaldehyde (3‐NBA), trinitrotoluene (TNT), 4‐nitrophenol (NP), and picric acid (PA) in solution state. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3800–3807     

An imidazole functionalized copper(II)-organic framework for highly selective sensing of picric acid and metal ions in water

An imidazole functionalized metal–organic framework (MOF), [Cu(HL)(H₂O)]·(H₂O)·(DMA) ( HBU-166 , H₃L = 4,4′,4″-(1H-imidazole-2,4,5-triyl)tribenzoic acid, DMA = N,N-dimethylacetamide) was synthesized and characterized by single-crystal X-ray diffraction. HBU-166 was observed as a two-dimensional MOF and showed good stability in water, an acidic solution (pH = 4), and an alkaline solution (pH = 9). HBU-166 exhibited ligand-based luminescence with a blue shift, which could be attributed to the coordination effect. Moreover, HBU-166 could be applied to detect nitroaromatic compounds (NACs) and metal ions in water with preferable selectivity and sensitivity. In particular, HBU-166 could be used as a promising luminescent sensor for picric acid (PA) with enhancement of emission intensity. The mechanism for PA detection likely involved electron transfer and weak interaction between ligand and electron-deficient of NACs at the beginning to increase the emission intensity. Additionally, HBU-166 exhibited excellent selectivity in the sensing of 4-nitrophenol and Fe³⁺ through fluorescence quenching.     

Synthesis,crystal structure and DNA interaction studies of a 2D cadmium(II) coordination polymer constructed from 2-(2-pyridyl)benzimidazole

A new complex associated with Cd²⁺, [Cd(OH-H₂Bdc)(2-Pbim)]_n (1), (OH-H₂Bdc = 5-hydroxyisophthalic acid, 2-Pbim = 2-(2-pyridyl)benzimidazole), has been synthesised under hydrothermal conditions and characterised by elemental analysis, FT-IR spectroscopy, TG/DTG and fluorescence spectrum. Its in vitro cytotoxicity towards four selected tumour cell lines has been evaluated by an microculture tetrozolium assay, the results suggest that complex 1 displays greater inhibition than the free benzimidazole ligand. On the basis of the combination of absorption titration and fluorescence emission titration, the binding mode of complex 1 to calf thymus DNA has been investigated. Complex 1 can interact with the base pairs of double-helical DNA via the combined mode of intercalation and groove binding with larger binding constants.     

Synthesis and Electrochemical,Fluorescent and Magnetic Properties of a New Cadmium(II) Complex with 2-Benzoylbenzoic Acid

A new cadmium(II) complex Cd(OBBA)2(2,2A-bipy)2 with 2-benzoylbenzoic acid(HOBBA) and 2,2-bipyridine(2,2A-bipy) as ligands has been synthesized. Crystal data for the complex are as follows: monoclinic, space group P21/c with a = 16.402(3), b = 10.4191(18), c = 23.395(4) A, β = 91.765(2)o, V = 3996.2(12) A3, Dc = 1.455 gAcm-3, Z = 4, μ(Mo Kα) = 0.603 mm-1, F(000) = 1784, the final R = 0.0218 and w R = 0.0558. In the electrode reaction, its electron transfer is quasi reversible and the electrode reaction corresponds to Cd(II)/Cd(0). Under 618 nm radiation, the title complex shows a strong fluorescent band at around 326 nm. In addition, in the range of 2~300 K, this complex displays diamagnetic property.     

Synthesis,Structure and Fluorescent Property of a Cadmium (II) Polymer

1 INTRODUCTION In recent years, lots of studies on the poly- nuclear cadmium compounds[1, 2] have been carried out carefully for their novel open-framework stru- cture motifs with channels and good fluorescent properties[3, 4]. Some organic bridging lig…     

Hexanuclear 3d − 4f metal–organic cages assembled from a carboxylic acid‐functionalized tris‐triazamacrocycle for highly selective fluorescent sensing of picric acid

Two Ln^III ions are sandwiched by dinuclear Co^II building blocks derived from a tris‐triazamacrocyclic ligand bearing pendant carboxylic acid functionality, 1,3,5‐tris((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐benzene (H₆L), giving rising to two nanoscale heterometallic metal–organic cages formulated as [Co₄Ln₂(LH_2.5)₂(H₂O)₄]·(ClO₄)₆·NO₃·nH₂O [Ln = Dy, n = 12 ( 1 ); Ln = Yb, n = 9 ( 2 )], whose internal cavity accommodates a guest NO₃^? anion. Their hexanuclear cage‐like architectures are maintained both in solution and solid states as confirmed by mass spectrum as well as X‐ray diffraction experiments. These two cages display ligand‐based fluorescence emissions and therefore both were chosen to be operated as fluorescent chemosensors for the detection of nitroaromatic compounds. Attractively, these metal–organic cages allow highly selective and sensitive detection of picric acid (PA) over other nitroaromatics in solution and suspension, and the fluorescence resonance energy transfer (FRET) between the cage probes and PA is mainly responsible for the remarkable detection efficiency.     

A dual functional 1D Cd-based coordination polymer for the highly luminescent sensitive detection of Fe3+ and picric acid

Fluorescent coordination polymers have drawn extensive attention in sensing applications. Herein, we report a carbazole-based one-dimensional coordination polymer [CdL(H₂O)(DMF)₂]·DMF ( CdL , H₂L = 9H-carbazole-2,7-dicarboxylic acid, DMF = N,N-dimethylformamide). In CdL , each Cd²⁺ ion is four-bridged by carboxylates, which is further linked by the carbazole units to form a one-dimensional Cd–O–C chains along the c-axis. CdL displays high water stability in the pH range of 3–10. Luminescence experiments indicate that CdL could selectively detect Fe³⁺ during the concentration range of 0–0.1 mm in water with a K_sv of 8022 m ⁻¹ and picric acid (PA) within the concentration range of 0–0.05 mm in methanol solution with a K_sv of 17948 m ⁻¹ respectively. The above results reveal that CdL can be applied as a multiresponse luminescence sensor for selectively sensing for Fe³⁺ in water and PA in methanol solution.     

1D Chain and 3D framework of silver(I) organo-metallic polymers self-assembled with triptycene

For the purpose of investigating the coordination behavior of sterically congested alkenes and exploring the possibility of non-planar complexation in the polycyclic aromatic system for formation of extended polymeric networks, triptycene (tpty) has been studied with regard to its complexation with the silver(I) ion. The crystal structures of [Ag(tpty)(THF)₂](ClO₄) (1) and [Ag₆(tpty)₄(CF₃SO₃)₂(H₂O)₆](CF₃SO₃)₄ (2) have been determined by single-crystal X-ray diffraction. The polycyclic aromatic hydrocarbon triptycene is found to offer a potential site for complexation, which can be utilized to generate an interesting array of organo-metallic polymers with one-dimensional (1D) chain and three-dimensional (3D) porous frameworks.     

Three multinuclear Co(II), Zn(II) and Cd(II) complexes based on a single-armed salamo-type bisoxime: syntheses,structural characterizations and fluorescent properties

Three multinuclear complexes, [Co(L)(OAc)Co(CH₃CH₂OH)₂]·H₂O, [Zn(L)(OAc)Zn(CH₃OH)], and [{Cd(L)(OAc)Cd(CH₃OH)}₂], containing a single-armed salamo-type bisoxime H₃L have been synthesized and characterized structurally. The Co(II) complex forms a dimeric unit by intermolecular hydrogen bond interactions of neighboring dimeric molecules. The Zn(II) complex also forms a dimeric unit by intermolecular hydrogen bond interactions. Interesting features of the crystal structure include O?O short contacts. Meanwhile, self-assembling infinite 1-D, 2-D, and 3-D supramolecular structures are formed by intermolecular hydrogen bond and C–H?π interactions. The Cd(II) complex forms an infinite 2-D supramolecular structure by intermolecular hydrogen bond interactions. The photophysical properties of the Co(II), Zn(II), and Cd(II) complexes have also been discussed.     

Hydrothermal Synthesis, Crystal Structure and Luminescence Properties of a New 2D Cadmium Complex Based on the 4,4'-Bis(benzimidazol-1-ylmethy1)biphenyl and Glutaric Acid Ligands

A new polymeric complex {Cd2(bbmb)2(gt)2·(H2O)2}n (bbmb = 4,4'-bis(benzimidazol-1-ylmethy1)biphenyl, H2gt = glutaric acid) has been obtained by hydrothermal method and structurally characterized by elemental analysis, IR, XRD, TGA and single-crystal X-ray diffraction. The complex belongs to the triclinic system, space group P1 with a = 10.2417(15), b = 13.752(2), c = 22.201(3), α = 73.899(2), β = 88.416(2), γ = 78.305(2)°, V = 2940.4(7)3 , Z = 2, C66H56Cd2N8O8 , Mr = 1313.99, Dc = 1.484 g/cm3 , F(000) = 1336 and μ= 0.787 mm-1 , and features a 2D network. In the solid state at room temperature, the cadmium(Ⅱ) complex exhibits strong fluorescence absorption at 435 nm (λmax).     

A mercury(II)-radical complex with a 1D ladder structure

Interaction of HgI₂ with a new long rigid nitronyl nitroxide radical ligand, 2-[4-(2-pyridin-4-yl-vinyl)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (L), leads to the formation of the mercury-radical complex [Hg₂I₄L₂] _n (1). The single crystal structure analysis reveals that 1 exhibits a one-dimensional (1D) ladder structure. Magnetic susceptibility data of 1 were simulated by a uniform chain model composed of the NIT–NIT dimers, indicating that there exist an antiferromagnetic exchange between the nitroxides within the dimer (J ₁ = ?8.41 cm^?1) and a very weak interdimer antiferromagnetic interaction (J _c = ?0.39 cm^?1).     

Synthesis and Crystal Structure of a New 2D Honeycomb-like Cadmium(II) Complex with Tripodal Ligand

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1D coordination polymers of Cu(II) and Cu(II) dimers with a dicyanomethanide ligand

Several new 1D coordination polymers have been synthesised using the anionic ligand carbamoyldicyanomethanide, C(CN)₂(CONH₂)⁻ (cdm). The polymeric complexes [Cu(cdm)₂(py)₂]·2MeOH (1), [Cu(cdm)₂(4-Etpy)₂]·2MeOH (2), [Cu(cdm)₂(3,5-Me₂pzH)₂]·2MeOH (3) and [Cu(cdm)₂(3-HOCH₂py)₂]·2MeOH (4) (py = pyridine; 3,5-Me₂pzH = 3,5-dimethylpyrazole) contain Cu(II) atoms bridged by μ₂-(N,N′) cdm ligands between equatorial and axial coordination sites. The use of monodentate co-ligands brings about polymeric products, in contrast to the use previously of chelating co-ligands which facilitate the formation of discrete products. These 1D polymeric complexes are connected by hydrogen bonding between the amide functionalities and the lattice solvent. In the structures of 3 and 4 the neutral ligands also contain hydrogen bond donor groups that supplement the amide ring motif. Two other complexes have been obtained that are polymeric chains of alkoxide-bridged Cu(II) dimers. The complexes [Cu(cdm)(MeO)(2-amp)] (5) and [Cu(cdm)(dmap)] (6) (2-amp = 2-(aminomethyl)pyridine and dmap = dimethylaminopropoxide) are remarkably similar despite the different ligands that they contain. Bridging between dimers is via μ₂-(N,O) cdm ligands, consequently altering the nature of the hydrogen bonding between adjacent chains compared to the simple polymeric species 1–3.