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The current work assessed the degradation degree and the degradation products derived from norfloxacin (NOR) and gentamicin (GEN) using iodosylbenzene and iodobenzene diacetate, in the presence of manganese porphyrin as catalysts. Better results for NOR degradation (> 80%) were obtained when more hydrophobic porphyrins were employed. β-brominated manganese porphyrins showed a lower GEN degradation (~ 25%) than the non-brominated ones (~ 35%), probably due to their steric hindrance. In any case, complete mineralization was achieved neither for NOR nor for GEN, and the assignment of the generated products, complemented by the study of their toxicity, was an important step performed. From the obtained results, no correlation was found between the number of identified products and the reported toxicity value (rSpearman,NOR = 0.006; p value = 0.986 and rSpearman,GEN = − 0,198; p value = 0.583), which reinforces the idea of synergism and antagonistic phenomena. The higher degradation degree could have led to products of lower steric hindrance and easier penetration into the A. fischeri cells, which subsequently led to an increase in toxicity for these experiments. In most cases, the products presented higher toxicity than the original compound, which raises a concern about their occurrence in environmental matrices.

The hexadentate N2S2O2 donor ligand N,N’-bis(3,5-tert-butylsalicylidene) diphenyl disulfide-2,2’-diamine was synthesised by the condensation of 2-aminophenyl disulfide and 3,5-di-tert-butyl-2-hydroxybenzaldehyde and its molecular structure was confirmed by X-ray studies. One of the tert-butyl groups in the Schiff base has rotational disorder around the C–C bond with ratio 0.56:0.44. The palladium complexes were prepared by the direct reaction of PdCl2(CH3CN)2 and Schiff base ligands N,N’-bis (5-tert-butylsalicylidene) diphenyl disulfide-2,2’-diamine and N,N’-bis(3,5-tert-butylsalicylidene) diphenyl disulfide-2,2’-diamine, respectively. The structure of the metal complexes was characterized by physico-chemical and spectroscopic methods. Palladium is in square-planar geometry bonded to imine nitrogen and phenolic O in both the complexes. The catalytic efficiency of the palladium complexes was evaluated in the cross-coupling reactions; Heck-Mizoroki reaction of iodobenzene and methyl acrylate and the Suzuki-Miyaura reaction of phenylboronic acid and iodobenzene, which gave low to moderate yields. Higher conversions were obtained for 2a as catalyst due to the increase in the number of bulky tertiary butyl groups in the structure.

First reported by Joseph Bunnet et al., base-catalyzed halogen dance reaction has puzzled chemists for decades, to come up with new ideas regarding the mechanism of this chemical reaction. A series of deprotonation followed by fast metal-halogen exchanges are among the most recent mechanisms reported so far. Using density functional theory, DFT, computations and focused on the Bunnet type isomerization halogen dance reactions of iodobenzene derivatives, iodo-bridged transition state, TS, are proposed. The new TS is then used to lay out 8 possible isomerization and 18 possible disproportionation paths. The possible mechanistic pathways are then carefully analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. These mechanistic pathways, sketch a comprehensive pattern for base-catalyzed halogen dance. There is still a lot to study in the chemistry of poly halogenated aryls.

Schiff base Cu(II), Co(II), Ni(II), Cr(III) and Fe(III) complexes have been synthesized via the reaction of the 2-amino-3-hydroxy-4-bromopyridine with 2-chloro-5-nitrobenzaldehyde and different transition metal salts. The complexes have been characterized by several methods. In addition, the prepared complexes were tested as precursors for the synthesis of their corresponding metal oxides nanoparticles by controlled aerobic thermal decomposition at 500 °C. The structure, composition, morphology and particle size of the prepared nanostructured metal oxides were characterized by FTIR, X-ray powder diffraction and by scanning and transmission electron microscopy. In addition, the corresponding materials have been tested as catalysts in the heterogeneous selective “solvent free” oxidation of benzyl alcohol giving high selectivities to benzaldehyde. In addition, the nanostructured metal oxides gave, in general, higher conversions than those of the starting Schiff base metal complexes. Finally, the nanostructured metal oxides have been treated with an organometallic Pd(II) precursor to prepare Pd-doped metal oxides, which have been tested as catalysts in two different C–C coupling reactions, namely, the coupling reaction between iodobenzene and phenylboronic acid and the double coupling of iodobenzene with 2,6-dibromopyridin. In all cases interesting conversions and yields were observed for the nanostructured metal oxides.

In this contribution, the influence of the origin of the nickel salts and the applied temperature were investigated on the preparation of Ni nanoparticles by the reduction of hydrazine. The nanoparticles obtained were characterized by X-ray diffractometry, dynamic light scattering as well as transmission and scanning electron microscopies. Several nickel salts proved to be applicable; however, only the bromide and iodide nickel halides could be transformed into metallic nickel form under room temperature. Their catalytic activities were also tested in the cross-coupling reaction between iodobenzene and phenylboronic acid, and it was found that most catalysts performed superbly. An experimentally supported explanation for the varying catalytic activities of Ni nanoparticles derived from various halide salts is offered. Furthermore, an unusual crystal rearrangement was observed during the catalytic tests.

The commonly used hydrazine reduction method for the synthesis of Ni nanoparticles was integrated with the mechanochemical treatment of the nickel hydroxide precursors to modify the structural and catalytic attributes of the as-prepared metallic nickel materials. The precursors and the nanoparticles were studied by X-ray diffractometry, infrared spectroscopy, and dynamic light scattering as well as scanning electron microscopy. The changes in catalytic activities were followed in the Suzuki–Miyaura cross-coupling reaction between iodobenzene and phenylboronic acid and correlated with structural changes resulting from mechanochemical pretreatment.

Alkali and alkaline earth metal ions (Na+, K+, Cs+, Mg2+) exchanged MCM-22 zeolites were prepared and subsequently palladium (2 wt.%; Pd) was dispersed on above exchanged MCM-22 zeolite materials. All the MCM-22 materials were systematically characterized by FTIR, powder X-ray diffraction, N2 sorption analysis and temperature-programmed desorption (TPD) of CO2. The XRD pattern and FTIR data confirmed the existence of the MCM-22 framework structure even after exchanging bulky metal ions and palladium loading. TPD studies using CO2 supports that the cesium and magnesium incorporated MCM-22 possess a strong and large number of basic sites. The alkali and alkaline-earth metal ions exchanged MCM-22 catalysts were explored for industrially important eugenol isomerisation, whereas the palladium containing MCM-22 materials were utilised for Heck coupling reaction of styrene with iodobenzene. The Cs-MCM-22 showed the best activity for the eugenol isomerization with the isoeugenol yield of 76%. The Cs/Pd-MCM-22 was shown as promising heterogeneous catalyst for Heck coupling reaction of styrene with iodobenzene and yield 99% stilbene. For both isomerization and Heck coupling reaction, the catalysts retain their activities even after several runs. Among different alkali and alkaline earth ion-exchanged MCM-22 materials, cesium containing MCM-22 was shown as a promising catalyst for isomerization of lignin-derived biomass model compound viz., eugenol. Subsequently, the palladium dispersed CsMCM-22 was found to be the potential catalyst for Heck coupling under ambient conditions.

A series of biothiols involving N-acetyl-l-cysteine (NAC), penicillamine (PEN), homocysteine (Hcys) and cysteine (Cys), were employed as nucleation templates to synthesize Pd nanocatalysts for Suzuki coupling reaction. It is the first report to comparatively study the physicochemical properties of Pd nanoparticles synthesized by biothiols with different chemical structures. Through the characterizations of UV–Vis, FT-IR, TEM, XPS and HPLC, it is demonstrated that Pd(II) precursors can coordinate with biothiols mainly through thiol, amino/amido and carboxyl groups. NAC molecules are capable of generating uniform Pd nanoparticles with the size distribution from 2.2 to 3.3 nm. At the [PdCl42−]/[biothiol] of 6, NAC- and Hcys-stabilized Pd displays spherical particles with the average size of 3.3 and 3.6 nm respectively, whereas Cys- and PEN-capped Pd exhibit worm-like morphology with poor dispersion. NAC-capped Pd nanoparticles with the mean diameter of 3.3 nm and the Pd0 proportion of 63%, show highly active in Suzuki cross-coupling between iodobenzene and phenylboronic acid, with the turn over frequency (TOF) of 38625 mol biphenyl (mol Pd × h)−1 in EtOH/water = 1:2 at 60 °C. This work paves a promising way to construct highly active Pd nanocatalysts, with a facile modulation of the morphology, the particle size and the charge property via different biothiols. A series of biothiols were employed as nucleation templates to synthesize Pd nanocatalysts for Suzuki coupling reaction. This work paves a promising way to construct highly active Pd nanocatalysts, with a facile modulation of the morphology, the particle size and the charge property via different biothiols.

Based on a comprehensive DFT mechanism study, the reaction characteristics of β-C–H arylation of α-methyl pentanone with iodobenzene are revealed. In this reaction, glycine plays an important role as organic transient ligand, which can directly activate β-C–H of α-methyl pentanone together with metal Pd(II). And in the whole reaction, the formation of N=C bond during the condensation of pentanone and glycine and the breaking of N=C bond are two rate-determining steps. The energy barrier of TS4 and TS23 is 57.5 kcal/mol and 41.9 kcal/mol, respectively, which is higher than other transition states. Correspondingly, metal Pd(II) still is a wonderful catalyst in this reaction, which can flexibly coordinate with nonmetal atom (N, O, C) and form different inorganic metal intermediates. And these inorganic metal intermediates have significant function in further decreasing reaction energy barrier and inducing the formation of β-C–H arylation.

Here we report a novel structure-based microbial screening method for vinyl compound discovery, DISCOVER (direct screening method based on coupling reactions for vinyl compound producers). Through a two-step screening procedure based on selective coupling reactions of terminal alkenes, the thiol-ene reaction (1st step of screening) and Mizoroki-Heck reaction, followed by iodine test (2nd step of screening), microbes producing vinyl compounds like itaconic acid (IA) can be isolated from soil samples. In the 1st step of screening, soil sources are plated on agar medium supplemented with an antimicrobial agent, α-thioglycerol (TG), and a radical initiator, VA-044 (VA). In the 2nd step of screening, vinyl compounds produced in the cultures are labelled with iodobenzene via the Mizoroki-Heck reaction, followed by an iodine test, leading to the detection and characterisation of labelled products. We evaluated the validity of DISCOVER using IA and its producer Aspergillus terreus. Experimental data supported our hypothesis that IA reacts with TG in the medium via the thiol-ene reaction and consequently, A. terreus rapidly forms colonies on the agar medium because of the loss of the antimicrobial activity of TG. Using DISCOVER, high throughput and selective isolation of A. terreus strains producing IA was possible from soils.

Copper nanoparticles (CuNPs) and palladium nanoparticles (PdNPs) have attracted wide attention owing to their multifaceted utility in catalysis, sensors, and biomedical applications. Their therapeutic spectrum includes anticancer, antiviral, antibacterial, antifungal, antidiabetic, antioxidant potential which rationalizes the exploration of diverse physical, chemical, and biological routes for fabrication. In this article, we focused on bacterium-assisted design of nanostructured copper and palladium for applications in therapy against multidrug-resistant pathogens, dehalogenation of diatrizoate, Heck coupling of iodobenzene, polymer electric membrane fuel cell, metal recovery, and electronic waste management. Further, hypothesis behind microbial synthesis of PdNPs in E. coli containing [NiFe] hydrogenase Hyd-1 is discussed. Similarly, detailed mechanism of synthesis and stabilization in Cyanobacteria is also documented. Both CuNPs and PdNPs act as potent chemotherapeutic agents that can further be enhanced by conjugation with drugs and/or fluorophores and ligands for simultaneous diagnosis and targeted drug delivery to the cancer site or infection. These bacteriogenic nanoparticles can be used in sensors and pollution control.

The graphene supported Cu2O nanoparticles were prepared via a two-step liquid-phase method and exhibited high catalytic activity and stability for the Ullmann coupling of aryl halides with N–H containing compounds under mild and ligand-free conditions. The yield of C–N cross-coupling of imidazole with iodobenzene reached up to 97% with 0.5 mol% Cu (vs. reported 5–10 mol%). The high activity and stability of Cu2O/graphene are probably due to the unique structure of graphene, which can make Cu2O nanoparticles highly dispersed and prevent them from aggregation and oxidation.

Reaction of thiosalicylic acid and iodobenzene or 1-fluoro-2-nitrobenzene in the presence of two equiv. of K2CO3 in acetone–water afforded the according diaryl thioethers 1 and 2 bearing carboxyl groups. Treatment of thiosalicylic acid with benzyl bromide-type compounds under similar reaction conditions gave aryl benzyl thioethers 3–8 in excellent yields. Moreover, reactions of thiosalicylic acid and benzyl bromide in the presence of excess K2CO3 led to isolation of compound 9 (Leka et al. in Acta Cryst E69:o285–0286, 2013) through further esterification of the carboxyl group. Crystal structures of 2, 5–7 and 9 (Leka et al. in Acta Cryst E69:o285–0286, 2013), along with their spectroscopic properties are reported. Weak hydrogen-bonding interactions exist in compound 2 and isomers 5–7. Compounds 2 and 7 crystallize in the monoclinic space group P21/n and C2/c, respectively, with a = 12.04(3), b = 7.311(19), C=14.22(4) A, β = 93.94(3)°, and Z = 4 for 2, and a = 14.934(13), b = 5.116(5), C=33.76(3) A, β = 91.523(12)°, and Z = 8 for 7. The unit cell of 5 has triclinic P-1 symmetry with the cell parameters a = 5.4334(14), b = 7.7787(19), C=16.488(4) A, α = 76.601(3)°, β = 86.078(3)°, γ = 70.772(3)°, and Z = 2 for 5. Compound 6 crystallizes in the orthorhombic space group Pbca with a = 15.1881(12), b = 7.3288(6), C=23.7366(19) A, and Z = 8. Reactions of thiosalicylic acid and a series of aryl- or benzyl halides in the presence of K2CO3 in acetone–water resulted in the formation of according diaryl thioethers and aryl benzyl thioethers in excellent yields.

Electronic adjustment is one of the most commonly used strategies to improve the catalytic performance of heterogeneous catalysts. We prepared hexagonal ultrathin Pd nanosheets with edges modified by gold nanoparticles (Au@Pd nanosheets) using galvanic replacement method. By virtue of the electronic interactions between the Pd nanosheets and Au nanoparticles, the Au@Pd nanosheets exhibited excellent catalytic performances in the carbonylation of iodobenzene by carbon monoxide. The novel nanocomposites could be applied as model catalysts to explore electronic effects in catalysis.

A method of direct synthesis of ortho-acyloxylated azoarenes via palladium-catalyzed C–H bond activation was developed. The reaction proceeded was smoothly at room temprature and have better yield in shorter times. The obtained ortho-acyloxylated azoarenes could be efficiently converted into 2-hydroxyazobenzenes in good yields through a hydrolysis process. Many various ortho-acyloxylated azoarenes were obtained in moderate to high yields by palladium-catalyzed direct C(sp2)-H acyloxylation of aromatic azo compounds with PhI(OAc)2

A new series of titanium-containing helical silicates were prepared by doping of chiral sodium lactate in a sol–gel process. Characterizations revealed that the present titanium materials had good porosities, hexagonal symmetries, helical morphologies, as well as right-handed internal chiralities. Loading of chiral sodium lactate in preparation facilitated internal chiralities of synthetic products. In catalysis, the titanium materials showed moderate-to-excellent conversions, moderate-to-high stereoselectivities, and satisfactory recyclings for oxidation of aliphatic and aromatic alkenes by using solid oxidants such as iodobenzene diacetate and iodosylbenzene. Furthermore, both using ionic liquid as solvent and leaching of catalyst were studied. In general, titanium-containing chiral silicates were provided, and their applications in asymmetric catalysis were discussed too, which showed values on design of new efficient chiral catalysts.

A new dendrimer with a 1,2-diphenylacetylene core and PAMAM-type dendrons was obtained in 55 % yield by a palladium-catalyzed reaction assisted by silver oxide [(PPh3)2PdCl2/Ag2O] from hypercore derivative of 17α-ethynylestradiol and dendrons with iodobenzene as focal point. The structure of this new dendrimer was unambiguously established by 1H, 13C NMR, HETCOR, 1H–13C HMBC, and HRMS. Due to the structure and aqueous solubility of the dendrimer, preliminary in vitro antioxidant potential was evaluated by ferric reducing antioxidant power assay, showing values 84 % higher than reduced glutathione. From DPPH assay, it was concluded that the dendrimer exhibited a scavenging power slightly higher than ascorbic acid. Because of its properties, the synthesized dendrimer could be a good candidate for future assays in biological models for specific diseases where oxidative stress plays an important role.

Aminated polyacrylonitrile (PAN-NH) nanofiber mats prepared by electrospinning and then aminated by multiamines with different chemical structures have been used for the immobilization of palladium. The PAN-NH fiber morphologies were characterized by scanning electron microscopy (SEM) and the dispersion of palladium particles on the PAN-NH fiber were examined by transmission electron microscopy (TEM). The catalytic activity and recyclability of the prepared heterogeneous palladium catalysts have been evaluated by the Heck reaction of iodobenzene with n-butyl acrylate. It was found that the catalytic activities of PAN-NH-Pd catalysts could be correlated with the chelating energies of the PAN-NH fiber mats with Pd active species.

Lithium and sodium bis(trimethylsilyl)amides react with fluoro-, bromo-, and chlorobenzenes in THF or toluene to give a mixture of N,N-bis(trimethylsilyl)aniline and N,2-bis(trimethylsilyl)aniline. The latter compound is resulted from 1,3-shift of the trimethylsilyl group from nitrogen to ortho-carbon atom of the benzene ring. Effects of the solvent, halogen, and alkali metal nature as well as the reaction conditions on the ratio of isomers were examined. Reaction of iodobenzene with sodium bis(trimethylsilyl)amide in THF produces N,N-bis(trimethylsilyl)aniline and 2-iodo-N,N-bis(trimethylsilyl)aniline, while in toluene a mixture of three products, two indicated above and N,N-bis(trimethylsilyl)benzylamine, was obtained.

Three dihydroxylated acetophenone derivatives 2,6-(1a), 2,5-(2a), and 2,4-dihydroxyacetophenone (3a) were O-monoalkylated at moderate temperature (50 °C) using 3-bromopropyl-N-pyrrole. These monomers 6-(3′-N-pyrrolpropoxy)-2-hydroxyacetophenone (1b), 5-(3′-N-pyrrolpropoxy)-2-hydroxyacetophenone (2b), and 4-(3′-N-pyrrolpropoxy)-2-hydroxy acetophenone (3b) were isolated with acceptable yields (59–70 %). Their characterization was carried out with usual spectroscopic methods such as UV–vis, FTIR, NMR1H, 13C, Dept135, and elemental analysis. These pyrrolic compounds were deliberately chosen as electropolymerizable monomers to elaborate poly(pyrrole) films containing metallic centers useful as redox mediators covalently grafted on the surfaces of modified electrodes. Accordingly, we have initiated the synthesis of an original pyrrole-Ni(II)-Schiff base complex derived from 2,6-(1b) and 1,2-diaminoethane. This pyrrolic complex was electropolymerized onto glassy carbon (GC), platinum disk (Pt), and indium tin oxide (ITO) electrode surfaces. This electropolymerization was performed in acetonitrile via anodic oxidation of pyrrolic moieties by cyclic voltammetry. The efficiency of the electrochemical polymerization was investigated as a function of several parameters such as the nature of the electrode material, the number of voltammetric scans, and the scan rate dependence. The electrodeposited poly(pyrrole) films onto ITO surface was characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). This poly(pyrrole) matrix, containing metallic centers, was found to have good catalytic properties towards the reduction of iodobenzene and carbon dioxide CO2.

Synthesis of cis (E)-1-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-3-phenyl/aryl/heteroarylprop-2-en-1-ones from 1-phenyl-3-methyl-4-acetylpyrazol-5-one was achieved in good yield. s-cis (E)-1-(5-Hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-3-arylprop-2-en-1-ones were isomerized to s-trans (E)-4-(3-(phenyl/aryl/heteroaryl)acryloyl)-5-methyl-2-phenyl-1H-pyrazol-3(2 H)-ones using iodobenzene diacetate in dichloromethane at room temperature in excellent yield. The structure and geometry of these α,β-unsaturated ketones (pyrazolyl ketones) were established with the help of NMR, 2D NMR and HRMS techniques. The cytotoxicity of pyrazolyl chalcones showed that s-cis(E) 1-(5-Hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-3-(4-methylphenyl)-prop-2-en-1-one is active at very low concentrations (IC50 13.3 μM) against colon cancer cell line (HCT-116). The in vitro anti-microbial studies of pyrazolyl chalcones were also tested against gram-positive (B. subtilis, S. aureus) and gram-negative bacteria (E. coli) and for anti-fungal activity against C. albicansand A. niger.

A series of new quinolin-2-yl moiety linked hydrazones of various aryl/heteroaryl aldehydes has been prepared which on treatment with iodobenzene diacetate in dichloromethane yielded novel triazolo[4,3-a]quinoline derivatives. All the synthesized compounds were characterized on the basis of their FT-IR, 1H, 13C NMR, and mass spectral data. Compounds thus obtained were tested in vitro for their antibacterial activity against three Gram-positive bacterial, namely Enterococcus, Bacillus subtilis, and Staphylococcus aureus, and three Gram-negative bacterial strains, namely Psuedomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae using agar well diffusion method. The percentage similarity of all compounds was also assessed on the basis of physico-chemical and steric parameters as compared to a standard drug, Cefixime using Chem 3D software. Most of the compounds possessed good percentage similarity and exhibited admirable antibacterial activity when compared with the standard drug. Compounds (4a, 4b, 3a, 3c, and 3d) containing pyrazole moiety were found to be most effective against Gram-positive bacteria, S. aureus and B. subtilis.

Piperidines possessing ester functionality, such as 2-(methoxycarbonyl)piperidine (methyl pipecolinate), 3-(ethoxycarbonyl)piperidine (ethyl nipecotate), and 4-(ethoxycarbonyl)piperidine (ethyl isonipecotate), were used as N-nucleophiles in palladium-catalyzed aminocarbonylation of iodobenzene and iodoalkenes such as 1-iodocyclohexene and 17-iodoandrost-16-ene. While the aminocarbonylation of both iodoalkenes, carried out under mild reaction conditions, resulted in the exclusive formation of the carboxamide, the same reaction of iodobenzene brought about the mixture of the corresponding carboxamide and 2-ketocarboxamide. The chemoselectivity toward the latter compounds, formed via double carbonyl insertion, was substantially increased by using high carbon monoxide pressure (up to 40 bar). Carboxamides derived from iodoalkenes and ketocarboxamides derived from iodoarene have been obtained in moderate to high yields.

Catalytic routes for synthesis of alkyl benzoates by alkoxycarbonylation reactions and aryl benzoates by phenoxycarbonylation reactions of aryl iodides are described using a palladium–1,10-phenanthroline complex encaged in Y zeolite. Moderate to excellent yields (40–99 %) of various benzoates were obtained at low Pd loadings of 0.6 mol%. The catalyst could be effectively removed from the reaction mixture by a simple filtration process and was reused four times with only minor loss of activity. Furthermore, its catalytic activity was further highlighted by a comparison with another two supported Pd catalysts. The protocol has the advantages of easy handing, moderate to excellent yield, and catalyst recyclability.

A series of new 2,5-disubstituted-1,3,4-oxadiazoles 6(a–j) have been conveniently synthesized by intermolecular oxidative cyclization of (E)-2-(arylbenzylidene)-2-[(4-methoxyphenyl)amino]acetohydrazides promoted by iodobenzene diacetate as an oxidant. The synthesized compounds were characterized by elemental analyses, FT-IR, LCMS, 1H NMR, and 13C NMR spectral studies. All the compounds were evaluated for their in vitro antiproliferative effect using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay method against four human cancer cell lines (K562, Colo-205, MDA-MB 231, IMR-32) for the time period of 24 h. Among the analogs, compounds 6h and 6i showed good activity on all cell lines, whereas the other compounds in the series exhibited moderate activity.

A series of new 5-chloro-8-bromo-3-aryl-1,2,4-triazolo[4,3-c]pyrimidines (4a–j) have been accomplished in excellent yields by the oxidative cyclization of pyrimidinylhydrazines (3a–j) of various aryl aldehydes with one equivalents of iodobenzene diacetate in methanol. The chemical structures of the synthesized compounds were confirmed by elemental analyses, FT-IR, 1H NMR, 13C NMR, and mass spectral studies. Ten new compounds (4a–j) were tested in vitro for their antimicrobial activity against clinically isolated strains. Variable and modest activities were observed against the investigated strains of bacteria and fungi. Compounds 4f, 4i, and 4j demonstrated good antimicrobial activity against all the tested microbial strains.

Pd nanoparticles with narrow size distributions between 1.3 and 3.3 nm are prepared using G-/C-rich oligonucleotide as the template. These DNA-Pd nanoparticles efficiently catalyze the Suzuki coupling reaction and exhibit highly catalytic activities under mild conditions, which are greatly dependent upon the particle size of Pd nanoparticles besides the DNA sequence. For the coupling reaction of iodobenzene and phenylboronic acid at 60 °C in the presence of KOH, it can be achieved high TOF value of 2646 mol biphenyl (mol Pd × h)−1 over AG22-Pd and 3640 mol biphenyl (mol Pd × h)−1 over CT22-Pd. Under the optimal experimental conditions, the yield of 100 % in biphenyl is obtained with only 0.0055 mol% AG22-Pd at 60 °C for 1 h in the solvent of EtOH/H2O (1:2) using Na2CO3 or K2CO3 as the base. It is illustrated that G-/C-rich oligonucleotides are promising templates to modulate easily the morphology of Pd nanoparticles in aqueous solution with high catalytic activity.

The thermal properties of hypervalent iodine reagents (iodobenzene diacetate, bis(trifluoroacetoxy)iodobenzene, [hydroxyl(mesyloxy)]iodobenzene, [hydroxy(tosyloxy)] iodobenzene) and polymer-supported hypervalent iodine reagents (polystyrene-supported iodobenzene diacetate, polystyrene-supported bis(trifluoroacetoxy)iodobenzene, polystyrene-supported[hydroxyl(mesyloxy)]iodobenzene, polystyrene-supported [hydroxy(tosyloxy)] iodobenzene) were investigated using thermogravimetry (TG) and differential scanning calorimetry (DSC). The polystyrene-supported iodobenzene diacetate, synthesized from polystyrene, was a precursor to other three polymer-supported hypervalent iodine reagents (PS-HTIB, PS-HMIB and PS-BTI). The TG curves of hypervalent iodine reagents and their polymer analogues show mainly one-step mass loss behaviour, whereas enthalpy change (∆H) and onset temperature were calculated from a DSC curve which that shows hypervalent iodine reagents and their polymer analogues decompose endothermically. The results suggest that the polymer-supported hypervalent iodine reagents are more stable than hypervalent iodine reagents and therefore may be used in reactions without decomposition up to 350–410 °C in comparison to the polymer-supported hypervalent iodine reagents that are stable up to 132–160 °C.

Inspired by the composition of adhesive and reductive proteins secreted by marine mussels, polydopamine (PDA) was used to coat cotton microfiber (CMF) and then acted as reducing agent for the growth of Pd nanoparticles on PDA coated CMF (PDA@CMF) composites. The resultant CMF@PDA/Pd composites were then packed in a column for the further use in fixed-bed system. For the catalysis of the reduction of 4-nitrophenol, the flow rate of the 4-aminophenol solution (0.5 mM) was as high as 60 mL/min. The obtained fixed-bed system even exhibited superior performance to conventional batch reaction process because it greatly facilitated the efficiency of the catalytic fibers. Consequently, its turnover frequency (TOF) was up to 1.587 min−1, while the TOF in the conventional batch reaction was 0.643 min−1. The catalytic fibers also showed good recyclability, which can be recycled for nine successive cycles without a loss of activity. Furthermore, the catalytic system based on CMF@PDA/Pd can also be applied for Suzuki coupling reaction with the iodobenzene conversion up to 96.7%. The strategy to prepare CMF@PDA/Pd catalytic fixed bed was simple, economical and scalable, which can also be applied for coating different microfibers and loading other noble metal nanoparticles, was amenable for automated industrial processes.

In this work, we described the synthesis of a nanocatalyst, which consists of polyaniline (PANI)/multiwall carbon nanotubes (MWCNTs) and the deposited Pd nanoparticles. FT-IR, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis (TG) and transmission electron microscopy were used to characterize the nanocatalyst. The interaction between PANI and MWCNTs have been explained according to the results of the FT-IR and XRD analysis. This complex was an efficient catalyst for the Heck reactions of acrylic acid with aryl iodides in air at low temperature (60 °C) using 0.9 mol% Pd of the catalyst. Furthermore, it also exhibited catalytic properties for the bromide and activated chlorobenzene. The yield of cinnamic acid was 71 % for the Heck reaction of acrylic acid with iodobenzene even though the complex was used nine times.

Ethylenediamine-functionalized activated carbon anchored palladium catalyst was prepared via grafting ethylenediamine onto chemically modified activated carbon, followed by the reaction with palladium chloride and then the reduction with potassium borohydride. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicated that palladium immobilized on the carrier via coordination bond in this catalyst. Transmission electron microscopy images showed that the supported palladium is in the form of near spherical particles smaller than 10 nm diameter and evenly dispersed on the surface of the carrier. This catalyst was applied for the Heck reaction of aryl halides with olefins. The influences of solvents, bases, reaction temperatures and times on catalytic property of the catalyst were investigated by using the coupling of iodobenzene and styrene as a probe reaction. By varying the combination of aryl halides and olefins, this catalyst showed effective catalytic activities to produce corresponding coupling products with moderate to excellent yields. Moreover, it can be recovered by simple filtration and reused several times without significant loss of activity and selectivity.

PdCl2(bipy) was found to be an efficient and stable catalyst in biphasic medium (organic-glycol) for the Heck reaction. The kinetics of the Heck coupling of styrene with iodobenzene using the same catalyst was studied in a biphasic medium in a temperature range of 393–413 K. The rate was found to have a first order dependence tending to a fractional order, on the iodobenzene as well as catalyst concentration. The rate was found to have a complex dependence on the styrene concentration and passes through a maximum, showing typical substrate inhibition kinetics. The rate had a first order dependence on the base (morpholine) concentration. The trends observed for the influence of the different parameters on the activity of the catalyst are in agreement with the established mechanism for Heck reaction. An empirical rate model has been proposed to fit the observed rate data. The activation energy was found to be 72.91 kJ/mol. This is the first time that kinetic modeling of Heck reaction in a biphasic medium (organic-glycol) has been attempted.

A simple, solvent-free and effective method for oxidative cyclization of 2-pyridyl- and 2-quinolyl-hydrazones with phenyliodine bis(trifluoroacetate) and iodobenzene diacetate to the corresponding 3-aryl[1,2,4]triazolo[4,3-a]pyridines and 1-aryl[1,2,4]triazolo[4,3-a]quinolines is described. All reactions were characterized by short reaction times and high yields at room temperature. All reactions were carried out by just grinding the reaction components.

A simple, efficient and expeditious method for synthesis of 2-arylbenzo[b]furans and 2-ferrocenylbenzo[b]furans from readily prepared propargylic alcohols, o-iodophenols and silica gel with the catalyst of PdCl2(PPh3)2 (2 mol%)/CuI (2 mol%) and microwave-promoted Sonogashira coupling/cyclization reaction is developed. The methodology can produce good to excellent yields. In addition, this method can also be completed in one-pot with iodobenzene, 2-methyl-3-butyn-2-ol and 2-iodo-4-methylphenol as reactants.

Nano-structured CuO granules catalyze the C–N cross-coupling of amines with iodobenzene in excellent yields. The reaction is simple, efficient, and operates in air under ligand-free conditions.

Carbon encapsulated Au@Fe nanoparticles (NPs) were synthesized by the hydrothermal method, and the palladium NPs (12 nm) were immobilized on this hydroxyl-terminated support. The morphology, composition, content and magnetism of the samples were characterized. Compared with the commercial carbon-supported Pd catalyst, high catalytic activity, recyclability and selectivity were evaluated by the catalyst Pd/(C@(Au@Fe)) in the Heck reaction. Especially, in the Heck cross-coupling reactions of iodobenzene and methyl acrylate, the catalyst was reused 10 times without significant loss of activity. In addition, the catalyst was simply recycled by a magnetic field.

An efficient, facile, and mild oxidation of alcohols to the corresponding aldehydes or ketones with potassium peroxodisulfate and 2,2,6,6-tetramethylpiperidinyl-1-oxy in the presence of a catalytic amount of iodobenzene is reported. The oxidation proceeded in a mixed solvent to afford carbonyl compounds in moderate to excellent yields. A possible mechanism for the oxidation is proposed.

The electronic structures and substituent effects in o-, m-, and p-iodoanisoles have been investigated by ultraviolet photoelectron spectroscopy (UPS). The observed UPS bands were analyzed by combining empirical arguments and theoretical methods. Owing to the electron-donating nature of both iodo- and methoxy substituents, the first ionization potentials of the three iodoanisoles are lower than those of iodobenzene and anisole. The presence of the two substituents in iodoanisoles leads to an electron- rich structure, which might contribute to the observed high reactivity of iodoanisoles in a number of organic reactions.

The diiodides NdI2 and DyI2 react with nitrogen at an atmospheric pressure at 2704-550 °C to give the nitrides (LnI2)3N (Ln = Nd and Dy). The products obtained are insoluble in organic solvents; in THF, they rapidly disproportionate into LnI3(THF)3 and the iodide nitrides (NdI)3N2 of unclear structures. The nitrides (NdI2)3N and (DyI2)3N can be completely hydrolyzed into ammonia, the triiodide hydrates LnI3(H2O)2, and the monoiodide hydrates LnI(OH)2(H2O). A reaction of (NdI2)3N with excess iodobenzene in THF gives Ph3N and PhNH2 in 9 and 5% yields, respectively. Reactions of (NdI2)3N with propyl chloride, benzyl chloride, and acetyl chloride produce no nitrogen-containing products. A reaction of (NdI2)3N with CpK gives Cp3Nd(THF) in 63% yield.

The ionic palladium porphyrin featured with pyridinium tags at four meso-positions, palladium tetrakis-(N-methyl-4-pyridinium)-porphyrin iodide ([Pd(II)TMPy)P][I]4 (3), embedded in the similar structured ionic liquid of N-butyl pyridinium tetrafluoroborate ([Bpy]BF4) was found to be a highly efficient and recyclable catalytic system for the Heck cross-coupling of iodobenzene (derivatives) and ethyl acylate, with high turnover frequency of 56,000 h−1 under aerobic conditions. The active charge transfer transition occurred in 3-[Bpy]BF4 system during the Heck reaction could account for the efficiency in the catalytic coupling, which was observed in the UV–visible spectra.

Literature data available on the interaction of stable free radicals with gold nanoparticles (Au NPs) suggested the adsorption of stable-free radicals on the nanoparticles surface, and the possibility of exchange interaction between the unpaired electron from the free radicals and the conduction-band electrons of the metal [1, 2]. Au NPs, as well as gold salts, are able to catalyze different processes, like oxidation, C–C bond formation, additions, alkylations, etc. [3, 4]. Exchange reactions (the most convenient method to prepare functionalized nanoparticles) mechanism of the ligands involves also in the first step the formation of an organometallic reactive complex [5–7]. The mechanisms of such processes are still under consideration. Nonetheless, free radicals play a major role in the surface chemistry of metal nanoparticles. Our previous work demonstrates that Au NPs may abstract a hydrogen or a halogen atom from different substrates, yielding the corresponding short-lived radicals [8, 9]. However, there is little information about the final products derived from the free radicals formed on or near the metal surface. Till now, literature data suggest that stable-free radicals may stay adsorbed on the nanoparticles surface [1], while the short-lived radicals may react with the nanoparticles (as in the thiol exchange reaction occurs [8]). Aryl radicals may act as well as stabilizers in the synthesis of metal NPs, via a metal–carbon bond formation [10]. Short-lived radicals are very reactive species, and they can stabilize in very different ways (dimerization, abstraction of different atoms, radical ? radical reactions). The knowledge of the pathway followed by the radicals toward their final products may provide very useful information about catalysis by Au NPs. Our first aim was to use Au NPs as catalyst at room temperature in an Ullmann-type reaction (a well-known coupling reaction, performed in harsh conditions, which uses copper as catalyst; the mechanism involves an organocopper compound and does not follow a radical pathway [11]), using the classical reactants aniline and iodobenzene. First, we used the spin-trapping technique (see also supplementary data for more details) to test if, from aniline or from iodobenzene, phosphine-protected Au NPs [12] generate the corresponding short-lived radicals C6H5NH • and C6H5 , in the same way as for previous substrates [8, 9]. As expected, our results showed (Fig. 1) that, from both reactions, the corresponding free radicals were formed and trapped by a spin-trap (DMPO). The hyperfine coupling constants of the EPR spectra are in full agreement with the literature data [13], and the EPR spectra can be very well simulated (see supplementary data). The amount of free radicals formed (measured by double integral of the spectra) was up to 12%, as previous data showed [8]. Using an equimolecular mixture of aniline and iodobenzene, we expected as well the formation of diphenylamine, in a radical ? radical reaction (Scheme 1). Remarkably, no diphenylamine was found in the reaction mixture. An EPR spin-trapping test was also performed to check if the radicals are formed in the mixture of the two reactants, and the recorded spectra showed that a mixture Electronic supplementary material The online version of this article (doi:10.1007/s10853-008-2987-1) contains supplementary material, which is available to authorized users.

A magnetic-separated catalyst of chitosan-palladium complex (Fe3O4-CS-Pd) based on chitosan coated Fe3O4 microspheres was prepared by the “bottom-up” approach. The catalytic behavior of the catalyst in the cross coupling reaction of acrylic acid (AA) with iodobenzene (ArI) was investigated. Compared with the traditional homogeneous palladium catalysts, the catalyst was easily separated and reused.

The condensation of iodobenzene to biphenyl is an industrially important reaction due to its sig- nificant role in organic synthesis as drug intermediates. The reaction takes place in the presence of copper powder as catalyst. We have shown in this paper that the size of the copper nanoparticles as well as its ex- posed surface area is responsible for the yield of chemical reaction. The uncapped copper powder showed a 43% conversion of iodobenzene to biphenyl in 5 h under our experimental conditions. Same amount of copper nanoparticles (size, ~ 66 nm diameter) prepared by citrate capping showed 88% conversion of iodobenzene to biphenyl, which increased to about 95% when 8 nm diameter capped copper nanoparticles are used. Surpris- ingly, 5 nm size copper nanoparticles showed no change in the yield of about 95%.

Different modifications of the Heck reaction involving the activation of carbon-halogen and carbon-oxygen bonds by palladium (styrene phenylation with iodobenzene or benzoic anhydride and iodobenzene carbonylation, reductive coupling, and reduction) are studied by in situ31P NMR spectroscopy. The catalytic cycles of the reactions include oxidative addition to Pd(0) formed in situ. The product composition in this step depends strongly on the composition of the reaction mixture, which is related to PhX conversion in the main catalytic process and with the nature of the catalyst precursor. A new hypothesis as to the mechanism of the catalytic cycle in alkene arylation in the presence of phosphine ligands is suggested. This hypothesis is consistent with NMR monitoring data and with the value of the kinetic isotope effect.

New activated difluoroaromatic compounds having an internal acetylenic moiety were synthesized by reaction of trichloroacetaldehyde with fluorobenzene, followed by reaction with iodobenzene and cross coupling with acetylene in the presence of palladium complexes. According to the results of quantum-chemical calculations and 19F NMR data, the products are highly reactive compounds which can be used for the preparation of high-molecular-weight aromatic polyethers.

The Sonogashira reaction of iodobenzene with phenylacetylene in several room temperature ionic liquids was studied. A regeneration of the catalytical system immobilized in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) has been also investigated. The reactivity of different iodoarenes with terminal alkynes in [bmim]PF6 was studied as well.

This paper summarises the results of three projects. The first is concerned with developing general routes for the synthesis of lignans. In particular, two routes involving tandem conjugate addition reactions and Diels Alder reactions respectively that have been used to synthesise podophyllotoxin derivatives are described. The second project is concerned with the asymmetric synthesis of lignans and involves the application of these reactions, with the introduction of a menthyloxy group as a chiral auxiliary, to achieve the asymmetric synthesis of podophyllotoxin derivatives. The third project is concerned with the attempted biomimetic syntheses of podophyllotoxin derivatives using oxidative coupling reactions. Attention is focussed primarily on the use of hypervalent iodine reagents, which yield stegane and isostegane derivatives rather than podophyllotoxin derivatives. Other examples of biaryl coupling leading to stegane and isostegane derivatives are included, and other examples of lignan synthesis involving hypervalent iodine reagents are also described. Abbreviations: DDQ – 2,3-dichloro-5,6-dicyano-1,4-benzoquinone; DMAD – dimethyl acetylenedicarboxylate (dimethyl butynedioate); PIDA – phenyliodonium diacetate, iodobenzene diacetate; PIFA – phenyliodonium bis(trifluoroacetate), [bis(trifluoroacetoxy) iodobenzene]; Ra-Ni – Raney nickel; TBAF – tetrabutylammonium fluoride; TBDMS –t-butyldimethylsilyl; TFA – trifluoroacetic acid; TFAA – trifluoroacetic anhydride; TFE – 2,2,2-trifluoroethanol; TTFA – thallium(III) trifluoroacetate.

The kinetics of competitive phenylation of alkenes with iodobenzene over palladium complexes (the Heck reaction) was studied. The effect of one alkene on the arylation rate of another alkene conflicts with the conventional mechanism of the Heck reaction in which the arylated alkene is formed through the unimolecular step of palladium hydride β-elimination. Based on experimental data obtained, another mechanism is proposed in which a reaction product is formed through the transfer of palladium hydride to the initial alkene molecule.

The arylation of 1-phenyltetrazole-5-thione using a series of iodobenzene derivatives in the presence of cuprous chloride and a ligand such as ethylenediamine. It was shown that the use of microwave activation permitted shortening of the reaction time, increasing yields and simplification of the reaction products isolation.

The ligands 2-(diphenylphosphino)benzyl-(2-thiophene)methylimine (V) and 2-(diphenylphosphino) benzyl-(2-thiophene)ethylimine (VI) were prepared from 2-(diphenylphosphino)benzaldehyde and thiophene amines with very good yields. An equimolar reaction of V and VI with either PdCl2(cod) (cod = cyclooctadiene) or PdClMe(cod) afforded palladium(II) complexes I–IV. The molecular structure of II was confirmed by X-ray crystallography. The coordination geometry around the palladium atom exhibited distorted square planar geometry at the palladium centre. Complexes I, II, and IV were evaluated as catalysts for Heck coupling reactions of iodobenzene with methyl acrylate under mild reaction conditions; 0.1 mole % catalyst, Et3N base, MeCN reflux for 8 h, 80°C; isolated yield on a 10 mmol scale with catalyst I (64 %), II (68 %), and IV (58 %). They all exhibited significant activities.