A 2D Metal‐Organic Framework Based on 9‐(Pyridin‐4‐yl)‐9H‐carbazole‐3,6‐dicarboxylic Acid: Synthesis,Structure and Properties

A metal‐organic framework (MOF ) formulated as [Cd₂(μ₃‐L)₂(DMF )₄]•H₂O ( CdL ) [H₂L =9‐(pyridin‐4‐yl)‐ 9H ‐carbazole‐3,6‐dicarboxylic acid, DMF =N ,N ‐dimethylformamide] was synthesized under solvothermal condition. Crystal structural analysis reveals that CdL features the layered 2D framework with L^{2 −} ligands as 3‐connected nodes. The compound CdL emits blue‐violet light with the narrow emission peak and the emission maximum at 414 nm upon excitation at the maximum excitation wavelength of 340 nm. The compound CdL has a similar emission spectrum curve to the free H₂L ligand that indicates the emission of compound CdL should be originated from the coordinated L^{2 −} ligands.     

Synthesis,Crystal Structure and Thermal Behavior of 4,5‐Diacetoxyl‐2‐(dinitromethylene)‐imidazolidine

A new energetic material, 4,5‐diacetoxyl‐2‐(dinitromethylene)‐imidazolidine (DADNI), was synthesized by the reaction of 4,5‐dihydroxyl‐2‐(dinitromethylene)‐imidazolidine (DDNI) and acetic anhydride, and characterized by single crystal X‐ray diffraction. Crystal data for DADNI are monoclinic, space group C2/c, a=15.9167(3) Å, b=8.6816(4) Å, c=8.5209(3) Å, β=103.294(9)°, V=1145.9(3) ų, Z=4, µ=0.150 mm⁻¹, F(000)=600, D_c=1.682 g·cm⁻³, R₁=0.0565 and wR₂=0.1649. Thermal decomposition behavior of DADNI was studied and an intensely exothermic process was observed. The kinetic equation of the decomposition reaction is: dα/dT=(10^16.64/β)×4α^3/4exp(−1.582×10⁵/RT). The critical temperature of thermal explosion is 163.76°C. The specific heat capacity of DADNI was studied with micro‐DSC method and theoretical calculation method. The molar heat capacity is 343.30 J·mol⁻¹·K⁻¹ at 298.15 K. The adiabatic time‐to‐explosion of DADNI was calculated to be 87.7 s.     

Antibacterial Activities and Nuclease Properties of Two New Ternary Copper(II) Complexes with 2‐(4′‐Thiazolyl)‐benzimidazole and 2,2′‐Bipyridine/1,10‐phenanthroline

Two new complexes: [Cu(TBZ)(bipy)Cl]Cl·H₂O ( 1 ) and [Cu(TBZ)(phen)Cl]Cl·H₂O ( 2 ) [TBZ=2‐(4′‐thiazolyl)‐ benzimidazole, phen=1,10‐phenanthroline and bipy=2,2′‐bipyridine] have been synthesized and characterized by elemental analysis, molar conductivity, IR, and UV‐vis methods. Complex 2 , structurally characterized by single‐crystal X‐ray crystallography, crystallizes in the monoclinic space group P2₁/c in a unit cell of a=0.85257(12) nm, b=2.5358(4) nm, c=1.15151(13) nm, β=118.721(8)°, V=2.183.2(5) nm³, Z=4, D_c=1.624 g·cm⁻³, µ=1.367 mm⁻¹. The complexes, free ligands and chloride copper(II) salt were each tested for their ability to inhibit the growth of two gram‐positive (B. subtilis and S. aureus) and two gram‐negative (Salmonella and E. coli) bacteria. The complexes showed good antibacterial activities against the microorganisms. The interaction between the complexes and calf thymus DNA in aqueous solution was investigated adopting electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. Results suggest that the two complexes can bind to DNA by intercalative mode. In addition, the result of agarose gel electrophoresis suggested that the complexes can cleave the plasmid DNA at physiological pH and room temperature. Mechanistic studies with different inhibiting reagents reveal that hydroxyl radicals, and a singlet oxygen‐like copper‐oxo species are all involved in the DNA scission process mediated by the complexes.     

Topological analysis of the three‐dimensional coordination polymer poly[(μ4‐azido)[μ4‐5‐(pyridin‐4‐yl)tetrazolido]disilver(I)]

The title compound, [Ag₂(C₆H₄N₄)(N₃₎]_n, was obtained under hydrothermal conditions at 433 K. The asymmetric unit of the orthorhombic space group (Pna2₁) consists of two Ag⁺ cations, an anionic 5‐(pyridin‐4‐yl)tetrazolide (4‐ptz⁻) ligand and an anionic azide ligand. Both Ag⁺ centres are coordinated by four N atoms, forming a distorted tetrahedral coordination environment. When all the component ions are viewed as 4‐connected nodes, the whole three‐dimensional network can be regarded topologically as a new kind of 4,4,4,4‐connected net with the Schläfli symbol (4.8⁵)(4².8⁴)(4³.8³)₂.     

4‐(3‐Azaniumylpropyl)morpholin‐4‐ium chloride hydrogen oxalate: an unusual example of a dication with different counter‐anions

The mixed organic–inorganic title salt, C₇H₁₈N₂O²⁺·C₂HO₄⁻·Cl⁻, forms an assembly of ionic components which are stabilized through a series of hydrogen bonds and charge‐assisted intermolecular interactions. The title assembly crystallizes in the monoclinic C2/c space group with Z = 8. The asymmetric unit consists of a 4‐(3‐azaniumylpropyl)morpholin‐4‐ium dication, a hydrogen oxalate counter‐anion and an inorganic chloride counter‐anion. The organic cations and anions are connected through a network of N—H...O, O—H...O and C—H...O hydrogen bonds, forming several intermolecular rings that can be described by the graph‐set notations R₃³(13), R₂¹(5), R₁²(5), R₂¹(6), R₂³(6), R₂²(8) and R₃³(9). The 4‐(3‐azaniumylpropyl)morpholin‐4‐ium dications are interconnected through N—H...O hydrogen bonds, forming C(9) chains that run diagonally along the ab face. Furthermore, the hydrogen oxalate anions are interconnected via O—H...O hydrogen bonds, forming head‐to‐tail C(5) chains along the crystallographic b axis. The two types of chains are linked through additional N—H...O and O—H...O hydrogen bonds, and the hydrogen oxalate chains are sandwiched by the 4‐(3‐azaniumylpropyl)morpholin‐4‐ium chains, forming organic layers that are separated by the chloride anions. Finally, the layered three‐dimensional structure is stabilized via intermolecular N—H...Cl and C—H...Cl interactions.     

Formation and Molecular Structure of an Ion Pair Iron (II) Compound Derived from 2,6‐Bis‐ [1‐(2,6‐dibromophenylimino) ‐ethyl] pyridine and 2‐Acetyl‐6‐[1‐(2, 6‐dibromophenylimino)‐ethyl] pyridine

Two novel tridentate ligands of 2,6‐bis‐[l‐(2,6‐dibromophenylimino) ethyl] pyridine (L₁) and2‐acetyl‐6‐[1‐(2,6‐dibromophenylimino) ethyl] pyridine (L2) have been synthesized. The iron(II) complex of L₁ and L₂ has been characterized with the crystal structure of [Fe(L₁)(L₂)]²⁺ [FeCl₄]² CH₂Cl₂ [monoclinic, P2₁ (#11), a = 1.0562(4), b = 2.0928(4), c = 1.2914(2) nm, β = 100.12°, V = 2.810(1) nm³ D_c = 1.879 g/cm³ and Z = 2].     

Structure and electrospray mass spectrometry studies on dithiacyclooctan-3-ol-containing palladium (II) complex of trans -[Pd(dtco-3-OH)_2](ClO_4)_2·2DMSO

The structure of trans-[Pd(dtco-3-OH)2] (ClO4)2·2DMSO, in which dtco-3-OH is dithiacyclooctan-3-ol and DMSO is dimethyl sulfoxide, was determined by X-ray crystallographic analysis. The crystal data: space group pi, a = 0.7077(2) nm, b = 1.0788(1) nm, c = 1.1111(1) nm, α=67.710(8)°, β = 73. 59(2)°, γ = 85. 39(2)°,R1 = 0 . 0368 and Rw = 0.0998. The palladium (II) is coordinated by four sulfur atoms with a regular square planar configuration. The Pd-S distances are 0.2314(1) and 0.2317(1) nm, respectively. Both dtco-3-OH ligands are in the boat-chair configuration and two hydroxyl groups are on the opposite sites of the PdS4 coordination plane and are towards Pd(II). The Pd-O distance is 0. 285 nm, indicating a weak interaction between them. A typical hydrogen bond between the hydroxyl group of dtco-3-OH ligand and DMSO was observed in the crystal structure. An aqueous solution prepared with the crystals of the complex was used for the investigation of electrospray mass spectrometry ( ESMS ). Besid     

Synthesis of 4-(4-Methylsulfonylphenyl)-3-phenyl-2(3H)-thiazole Thione Derivatives as New Potential COX-2 Inhibitors

Synthesis of novel 4-（4-methylsulfonylphenyl）-3-phenyl-2（3H）-thiazole thione derivatives with functionalized diarylheterocycle pharmacophore as potential COX-2 inhibitors was described. The title compounds were synthesized by cyclocondensation of corresponding dithiocarbamate and 2-bromo-1-（4-methylsulfonylphenyl）ethanone, followed by dehydration with H2SO4. All of the target compounds were characterized by ^1H NMR, IR and mass spectral data.     

Reactivity Towards Europium(III) of the Radiolysis Products of the Ionic Liquid 1‐Methyl‐3‐butyl‐1H‐imidazolium Bis[(trifluoromethyl)sulfonyl]amide (C4‐mimTf2N) and Effect of Water: A TRLFS (Time‐Resolved Laser‐Induced Fluorescence Spectroscopy) Preliminary Study

The effect of laser irradiation at λ_exc 266 nm onto the fluorescence characteristics of Eu^III in solution of the ionic liquid 1‐methyl‐3‐butyl‐1H‐imidazolium bis[(trifluoromethyl)sulfonyl]amide (C₄‐mimTf₂N) was examined for various amounts of H₂O added. Stable radiolytic products that were generated at very low doses (in the range of 4 kGy) were very reactive with Eu^III and led to the appearance of a new europium luminescent species that was characterized by lifetime, relative intensity, and emission spectrum. Although the lifetime and the intensity depended on the H₂O content, the emission spectrum was not influenced by H₂O. It was shown that large amounts of H₂O, although not preventing radiolysis of C₄‐mimTf₂N, inhibited the complexation with Eu^III.     

Isophorone－based Fluorescent Dopant for Red Organic Electrolumi－nescence Device

lsophorone-based red fluorescent compound 3-(dicyanomethy-lene ) -5, 5-dimethyi- 1- [ 2- ( N-ethyl-3-carbazyi ) ethylene ] cyciohe-xene (DCDCC) was synthesized for use in organic Hght-emit-ring diodes (OLEDs). DCDCC was characterized by narrow emission in photoluminescence with full.width at half-maximum of only 50 nm in solution and in thin solid film of 70 nm width. devices with configuration of ITO/NPB/Alq3:DCDCC/Alq3/Mg: Ag were fabricated utilizing DCDCC as dopant emitter. An efficient red emission peaked at 612 nm was obtained for the device with 1% (wt.%) DCDCC in Alq3. The maximum luminance and current efficiency were as high as 3700 cd/m^2 at 14 V and 1.25 cd/A at 150 mA/cm^2, respective-ly.     

Coordination chemistry of organometallic polydentate ligand Reactive chemistry of the tridentate ligand trans‐Fe(Ph2PQu‐P)2‐(CO)3 [PhzPQu=2‐diphenyl‐phosphino‐4‐methylquinoline] and molecular structure of [Fe(CO)3(μ‐Ph2PQu)2HgI]+ [HgI3]

Reaction of a new type of bidentate ligand PhPQu [PhPQu = 2‐diphenylphosphino‐4‐methylquinoline] with Fe(CO)₅ in butanol gave trans‐Fe(FpPQu‐P)(CO)₃ (1). Compound 1, which can act as a neutral tridentate organometallic ligand, was reacted with I B, II B metal compounds and a rhodium complex to give six binuclear complexes with Fe? M bonds, Fe(CO)₃ (μ‐Ph₂PQu)MX_n (2–7) [M= Zn(II), Cd(II), Hg(II), Cu(I), Ag(I), Rh(I)], and an ion‐pair complex [Fe(CO)₃ (μ‐Ph₂PQu)₂HgI][HgI₃]^? (8). The structure of 8 was determined by X‐ray crystallography. Complex 8 crystallizes in the space group P‐1 with a = 1.0758(3), b = 1.6210(4), c=1.7155(4)nm; a=75.60(2), β=71.81(2), γ=81.78(2)° and Z = 2 and its structure was refined to give agreement factors of R=0.050 and R_w = 0.057. The Fe‐Hg bond distance is 0.2536nm.     

Three novel topologically different metal–organic frameworks built from 3‐nitro‐4‐(pyridin‐4‐yl)benzoic acid

The design and synthesis of metal–organic frameworks (MOFs) have attracted much interest due to the intriguing diversity of their architectures and topologies. However, building MOFs with different topological structures from the same ligand is still a challenge. Using 3‐nitro‐4‐(pyridin‐4‐yl)benzoic acid (HL) as a new ligand, three novel MOFs, namely poly[[(N,N‐dimethylformamide‐κO)bis[μ₂‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ³O,O′:N]cadmium(II)] N,N‐dimethylformamide monosolvate methanol monosolvate], {[Cd(C₁₂H₇N₂O₄)₂(C₃H₇NO)]·C₃H₇NO·CH₃OH}_n, ( 1 ), poly[[(μ₂‐acetato‐κ²O:O′)[μ₃‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ³O:O′:N]bis[μ₃‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ⁴O,O′:O′:N]dicadmium(II)] N,N‐dimethylacetamide disolvate monohydrate], {[Cd₂(C₁₂H₇N₂O₄)₃(CH₃CO₂)]·2C₄H₉NO·H₂O}_n, ( 2 ), and catena‐poly[[[diaquanickel(II)]‐bis[μ₂‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ²O:N]] N,N‐dimethylacetamide disolvate], {[Ni(C₁₂H₇N₂O₄)₂(H₂O)₂]·2C₄H₉NO}_n, ( 3 ), have been prepared. Single‐crystal structure analysis shows that the Cd^II atom in MOF ( 1 ) has a distorted pentagonal bipyramidal [CdN₂O₅] coordination geometry. The [CdN₂O₅] units as 4‐connected nodes are interconnected by L^? ligands to form a fourfold interpenetrating three‐dimensional (3D) framework with a dia topology. In MOF ( 2 ), there are two crystallographically different Cd^II ions showing a distorted pentagonal bipyramidal [CdNO₆] and a distorted octahedral [CdN₂O₄] coordination geometry, respectively. Two Cd^II ions are connected by three carboxylate groups to form a binuclear [Cd₂(COO)₃] cluster. Each binuclear cluster as a 6‐connected node is further linked by acetate groups and L^? ligands to produce a non‐interpenetrating 3D framework with a pcu topology. MOF ( 3 ) contains two crystallographically distinct Ni^II ions on special positions. Each Ni^II ion adopts an elongated octahedral [NiN₂O₄] geometry. Each Ni^II ion as a 4‐connected node is linked by L^? ligands to generate a two‐dimensional network with an sql topology, which is further stabilized by two types of intermolecular OW—HW…O hydrogen bonds to form a 3D supramolecular framework. MOFs ( 1 )–( 3 ) were also characterized by powder X‐ray diffraction, IR spectroscopy and thermogravimetic analysis. Furthermore, the solid‐state photoluminescence of HL and MOFs ( 1 ) and ( 2 ) have been investigated. The photoluminescence of MOFs ( 1 ) and ( 2 ) are enhanced and red‐shifted with respect to free HL. The gas adsorption investigation of MOF ( 2 ) indicates a good separation selectivity (71) of CO₂/N₂ at 273 K (i.e. the amount of CO₂ adsorption is 71 times higher than N₂ at the same pressure).     

Synthesis of 3‐(ω‐Hydroxyalkoxy)isobenzofuran‐1(3H)‐ones by Trifluoroacetic Acid‐Mediated Lactonization of tert‐Butyl 2‐(1,3‐Dioxol‐2‐yl)‐ or 2‐(1,3‐Dioxan‐2‐yl)benzoates

An efficient two‐step method for the preparation of 3‐(2‐hydroxyethoxy)‐ or 3‐(3‐hydroxypropoxy)isobenzofuran‐1(3H)‐ones 3 has been developed. Thus, the reaction of 1‐(1,3‐dioxol‐2‐yl)‐ or 1‐(1,3‐dioxan‐2‐yl)‐2‐lithiobenzenes, generated in situ by the treatment of 1‐bromo‐2‐(1,3‐dioxol‐2‐yl)‐ or 1‐bromo‐2‐(1,3‐dioxan‐2‐yl)benzenes 1 with BuLi in THF at ?78°, with (Boc)₂O afforded tert‐butyl 2‐(1,3‐dioxol‐2‐yl)‐ or 2‐(1,3‐dioxan‐2‐yl)benzoates 2 , which can subsequently undergo facile lactonization on treatment with CF₃COOH (TFA) in CH₂Cl₂ at 0° to give the desired products in reasonable yields.     

N-(4-甲基苯甲酰氨基) N’-[5-(2-三氟甲基苯基)-2-呋喃甲酰硫脲的合成、晶体结构测定与生物活性测定

本文首次合成标题化合物N-(4-甲基苯甲酰氨基)-N’-[5-(2-三氟甲基苯基)-2-呋喃甲酰硫脲。化合物(C21H16F3N3O3S, Mr = 447.43)单晶经测定为单斜晶体,空间群为P -1。在晶体中,存在一些分子内和分子间的相互作用,分子间还有C—H···π 的相互作用,这可能导致晶体更稳定的原因。目标产物的结构经IR, H NMR和元素分析测定确证。初步生物活性测试表明,部分化合物对棉花枯萎病、黄瓜灰霉病、苹果轮纹病和棉花炭疽病有较好的选择性杀菌活性;部分目标化合物有较好的除草活性。     

Reaction‐path calculations and crystal structures of 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dichloride dihydrate and 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dibromide

The design of new organic–inorganic hybrid ionic materials is of interest for various applications, particularly in the areas of crystal engineering, supramolecular chemistry and materials science. The monohalogenated intermediates 1‐(2‐chloroethyl)pyridinium chloride, C₅H₅NCH₂CH₂Cl⁺·Cl⁻, (I′), and 1‐(2‐bromoethyl)pyridinium bromide, C₅H₅NCH₂CH₂Br⁺·Br⁻, (II′), and the ionic disubstituted products 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dichloride dihydrate, C₁₂H₁₄N₂²⁺·2Cl⁻·2H₂O, (I), and 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dibromide, C₁₂H₁₄N₂²⁺·2Br⁻, (II), have been isolated as powders from the reactions of pyridine with the appropriate 1,2‐dihaloethanes. The monohalogenated intermediates (I′) and (II′) were characterized by multinuclear NMR spectroscopy, while (I) and (II) were structurally characterized using powder X‐ray diffraction. Both (I) and (II) crystallize with half the empirical formula in the asymmetric unit in the triclinic space group P. The organic 1,1′‐(ethylene‐1,2‐diyl)dipyridinium dications, which display approximate C2h symmetry in both structures, are situated on inversion centres. The components in (I) are linked via intermolecular O—H…Cl, C—H…Cl and C—H…O hydrogen bonds into a three‐dimensional framework, while for (II), they are connected via weak intermolecular C—H…Br hydrogen bonds into one‐dimensional chains in the [110] direction. The nucleophilic substitution reactions of 1,2‐dichloroethane and 1,2‐dibromoethane with pyridine have been investigated by ab initio quantum chemical calculations using the 6–31G** basis. In both cases, the reactions occur in two exothermic stages involving consecutive S_N2 nucleophilic substitutions. The isolation of the monosubstituted intermediate in each case is strong evidence that the second step is not fast relative to the first.     

A Novel Route to 1‐Substituted 3‐(Dialkylamino)‐9‐oxo‐9H‐indeno[2,1‐c]pyridine‐4‐carbonitriles

Heptalenecarbaldehydes 1 / 1′ as well as aromatic aldehydes react with 3‐(dicyanomethylidene)‐indan‐1‐one in boiling EtOH and in the presence of secondary amines to yield 3‐(dialkylamino)‐1,2‐dihydro‐9‐oxo‐9H‐indeno[2,1‐c]pyridine‐4‐carbonitriles (Schemes 2 and 4, and Fig. 1). The 1,2‐dihydro forms can be dehydrogenated easily with KMnO₄ in acetone at 0° (Scheme 3) or chloranil (=2,3,5,6‐tetrachlorocyclohexa‐2,5‐diene‐1,4‐dione) in a ‘one‐pot’ reaction in dioxane at ambient temperature (Table 1). The structures of the indeno[2,1‐c]pyridine‐4‐carbonitriles 5′ and 6a have been verified by X‐ray crystal‐structure analyses (Fig. 2 and 4). The inherent merocyanine system of the dihydro forms results in a broad absorption band in the range of 515–530 nm in their UV/VIS spectra (Table 2 and Fig. 3). The dehydrogenated compounds 5, 5′ , and 7a – 7f exhibit their longest‐wavelength absorption maximum at ca. 380 nm (Table 2). In contrast to 5 and 5′, 7a – 7f in solution exhibit a blue‐green fluorescence with emission bands at around 460 and 480 nm (Table 4 and Fig. 5).     

Synthesis and Fungicidal Activity of (E)‐5‐[1‐(2‐Oxo‐1‐oxaspiro[4,5]dec/non‐3‐en‐3‐yl)ethylidene]‐2‐aminoimidazolin‐4‐one Derivatives

The novel fungicidal agents, (E )‐5‐[1‐(2‐oxo‐1‐oxaspiro[4,5]dec/non‐3‐en‐3‐yl)ethylidene]‐2‐aminoimidazolin‐ 4‐one derivatives, were designed and synthesized in moderate to excellent yields in four steps using α ‐hydroxyketone and diketene as raw materials and characterized by HR‐ESI‐MS , ¹H NMR and X‐ray diffraction. The preliminary bioassay showed that some of these compounds, such as 5e , 6a , 6e , and 7 h exhibit 87.8%, 91.3%, 89.9% and 87.8% inhibition rates against Sclerotinia scleotiorum , 3b , 3c , 4c and 7 h exhibit 96.4%, 92.5%, 90.3% and 76.9% inhibition rates against Phytophthora capsici at the concentration of 50 µg/mL , respectively. These compounds exhibited significant fungicidal activities against S. scleotiorum and P. capsici with EC₅₀ values of 2.56–11.60 µg/mL , and compounds 6e and 7 h exhibited weak inhibition against the spore germination of S. scleotiorum , while the spore germination of P. capsici was strongly inhibited by compound 7 h solution. Scanning electron microscopy (SEM ) and transmission electron microscopy (TEM ) observation indicated that compound 7 h had a significant impact on the structure and function of the hyphal cell wall of P. capsici mycelium.     

A one‐dimensional lead(II) coordination polymer with terminal and bridging 5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylate ligands

In the coordination polymer catena‐poly[[[diaqua[5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ²N³,O⁴]lead(II)]‐μ‐5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:N²] dihydrate], {[Pb(C₁₀H₆N₃O₄)(H₂O)₂]·2H₂O}_n, the two 5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylate ligands have different coordination modes, one being terminal and the other bridging. The bridging ligand links Pb^II cations into one‐dimensional coordination polymer chains. The structure is also stabilized by intra‐ and interchain π–π stacking interactions between the pyridine rings, resulting in the formation of a two‐dimensional network. Extensive hydrogen‐bonding interactions lead to the formation of a three‐dimensional supramolecular network.     

Kinetic Study of Peroxidase‐Catalyzed Coupling of Benzene‐1,4‐diamine and N‐(2‐Aminoethyl)naphthalen‐1‐amine: Development of Micromolar Hydrogen Peroxide Reaction System

A novel chromogenic method to measure the peroxidase activity using para‐phenylenediamine dihydrochloride (=benzene‐1,4‐diamine hydrochloride; PPDD) and N‐(1‐naphthyl)ethylenediamine dihydrochloride (=N‐(2‐aminoethyl)naphthalen‐1‐amine; NEDA) is presented. The PPDD entraps the free radical and gets oxidized to electrophilic diimine, which couples with NEDA to give an intense red‐colored chromogenic species with maximum absorbance at 490 nm. This assay was adopted for the quantification of H₂O₂ between 20 and 160 μM . Catalytic efficiency and catalytic power of the commercial peroxidase were found to be 4.47×10⁴ M ^?1 min^?1 and 3.38×10^?4 min^?1, respectively. The catalytic constant (k_cat) and specificity constant (k_cat/K_m) at saturated concentration of the co‐substrates were 0.0245×10³ min^?1 and 0.0445 μM ^?1 min^?1, respectively. The chromogenic coupling reaction has a minimum interference from the reducing substances such as ascorbic acid, L ‐cystein, citric acid, and oxalic acid. The method being simple, rapid, precise, and sensitive, its applicability has been tested in the crude vegetable extracts that showed peroxidase activity.