Allyloxyporphyrin‐Functionalized Multiwalled Carbon Nanotubes: Synthesis by Radical Polymerization and Enhanced Optical‐Limiting Properties

Allyloxyporphyrin‐functionalized multiwalled carbon nanotubes (MWCNT‐TPP) were synthesized by radical polymerization and characterized by FTIR, UV/Vis absorption, and X‐ray photoelectron spectroscopy; elemental analysis; TEM; and thermogravimetric analysis. Z‐scan studies revealed that this nanohybrid exhibits enhanced nonlinear optical (NLO) properties compared to a control sample consisting of a covalently unattached physical blend of MWCNTs and porphyrin, as well as to the separate MWCNTs and porphyrin. At the wavelengths used, the mechanism of enhanced optical limiting likely involves reverse saturable absorption, nonlinear scattering, and photoinduced electron/energy transfer between the MWCNTs and the porphyrin. The role of electron/energy transfer in the NLO performance of MWCNT‐TPP was investigated by Raman and fluorescence spectroscopy.     

Synthesis of porphyrin‐end‐functionalized polycyclohexane with well‐controlled and defined polymer chain structure

Tetraphenylporphyrin‐end‐functionalized polycyclohexane (H₂TPP‐PCHE) and its metal complexes (MTPP‐PCHE) were synthesized as the first successful example of porphyrin‐end‐functionalized transparent and stable polymers with a well‐controlled and defined polymer chain structure. Chloromethyl‐end‐functionalized poly(1,3‐cyclohexadiene) (CM‐PCHD) was synthesized as prerequisite prepolymer by the postpolymerization reaction of poly(1,3‐cyclohexadienyl)lithium and chloro(chloromethyl)dimethylsilane. CM‐end‐functionalized PCHE (CM‐PCHE) was prepared by the complete hydrogenation of CM‐PCHD with p‐toluenesulfonyl hydrazide. H₂TPP was incorporated onto the polymer chain end by the addition of 5‐(4‐hydroxyphenyl)‐10,15,20‐triphenylporphyrin to CM‐PCHE. The complexation of H₂TPP‐PCHE and Zn(OAc)₂ (or PtCl₂) yielded a zinc (or platinum) complex of H₂TPP‐PCHE. H₂TPP‐PCHE and MTPP‐PCHE were readily soluble in common organic solvents, and PCHE did not inhibit the optical properties of the H₂TPP, ZnTPP, and PtTPP end groups. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

meso‐3,5‐Bis(trifluoromethyl)phenyl‐Substituted Expanded Porphyrins: Synthesis,Characterization, and Optical,Electrochemical, and Photophysical Properties

Trifluoroacetic acid‐catalyzed condensation of pyrrole with electron‐deficient and sterically hindered 3,5‐bis(trifluoromethyl)benzaldehyde results in the unexpected production of a series of meso‐3,5‐bis(trifluoromethyl)phenyl‐substituted expanded porphyrins including [22]sapphyrin 2 , N‐fused [22]pentaphyrin 3 , [26]hexaphyrin 4 , and intact [32]heptaphyrin 5 together with the conventional 5,10,15,20‐tetrakis(3,5‐bis(trifluoromethyl)phenyl)porphyrin 1 . These expanded porphyrins are characterized by mass spectrometry, ¹H NMR spectroscopy, UV/Vis/NIR absorption spectroscopy, and fluorescence spectroscopy. The optical and electrochemical measurements reveal a decrease in the HOMO–LUMO gap with increasing size of the conjugated macrocycles, and in accordance with the trend, the deactivation of the excited singlet state to the ground state is enhanced.     

Synthesis of metal (Fe or Pd)/alloy (Fe–Pd)‐nanoparticles‐embedded multiwall carbon nanotube/sulfonated polyaniline composites by γ irradiation

Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) were prepared through the oxidative polymerization of a mixture of aniline, 2,5‐diaminobenzene sulfonic acid, and MWCNTs. Fe, Pd, or Fe–Pd alloy nanoparticles were embedded into the MWCNT–SPAN matrix by the reduction of Fe, Pd, or a mixture of Fe and Pd ions with γ radiation. Sulfonic acid groups and the emeraldine form of backbone units in SPAN served as the source for the reduction of the metal ions in the presence of γ radiation. The existence of metallic/alloy particles in the MWCNT–SPAN matrix was further ascertained through characterization by high‐resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and conductivity measurements. HRTEM pictures clearly revealed the existence of Fe, Pd, and Fe–Pd nanoparticles of various sizes in the MWCNT–SPAN matrices. There were changes in the electronic properties of the MWCNT–SPAN–M composites due to the interaction between the metal nanoparticles and MWCNT–SPAN. Metal‐nanoparticle‐loaded MWCNT–SPAN composites (MWCNT–SPAN–M; M = Fe, Pd, or Fe–Pd alloy) showed better thermal stability than the pristine polymers. The conductivity of the MWCNT–SPAN–M composites was approximately 1.5 S cm^?1, which was much higher than that of SPAN (2.46 × 10^?4 S cm^?1). Metal/alloy‐nanoparticle‐embedded, MWCNT‐based composite materials are expected to find applications in molecular electronics and other fields. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3355–3364, 2006     

Synthesis,crystal structure studies and solvatochromic behaviour of two 2‐{5‐[4‐(dimethylamino)phenyl]penta‐2,4‐dien‐1‐ylidene}malononitrile derivatives

The synthesis, crystal structure studies and solvatochromic behavior of 2‐{(2E,4E)‐5‐[4‐(dimethylamino)phenyl]penta‐2,4‐dien‐1‐ylidene}malononitrile, C₁₆H₁₅N₃ (DCV[3]), and 2‐{(2E,4E,6E)‐7‐[4‐(dimethylamino)phenyl]hepta‐2,4,6‐trien‐1‐ylidene}malononitrile, C₁₈H₁₇N₃ (DCV[4]), are reported and discussed in comparison with their homologs having a shorter length of the π‐conjugated bridge. The compounds of this series have potential use as nonlinear materials with second‐order effects due to their donor–acceptor structures. However, DCV[3] and DCV[4] crystallized in the centrosymmetric space group P2₁/c which excludes their application as nonlinear optical materials in the crystalline state. They both crystallize with two independent molecules having the same molecular conformation in the asymmetric unit. The series DCV[1]–DCV[4] demonstrated reversed solvatochromic behavior in toluene, chloroform, and acetonitrile.     

Synthesis and studies of thermal,mechanical and electrical properties of MWCNT–cyclodextrin as a nanoparticle in polyamide matrix based on 2,2‐Bis[4‐(4‐aminophenoxy)phenyl] propane

In the present research, polyamide (PA) ( 6 ) was synthesized by the polycondensation reaction of 2,2‐Bis[4‐(4‐aminophenoxy)phenyl] propane as a diamine ( 4 ) with adipic acid ( 5 ) in the optimized condition. The resulting PA was characterized using Fourier transform infrared spectroscopy, Proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy, inherent viscosity (η_inh), X‐ray diffraction, and solubility tests. Also, the thermal property of the new PA ( 6 ) was investigated by using Thermogravimetric analysis. To apply multiwall carbon nanotube (MWCNT) as an effective reinforcement in polymer composites, it is essential to have appropriate proper dispersion, interfacial adhesion between the MWCNT and polymer matrix, and increasing solubility. With this end particularly, functionalized MWCNTs were combined with a soluble molecule, and a series of modified MWCNT with cyclodextrin (Cy) known as PA/MWCNT‐Cy composite film (2, 5, and 8 wt%) were prepared by a solution intercalation technique. Field emission scanning electron microscopy images showed that MWCNT‐Cy was well dispersed in the PA matrix. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared with the pristine PA. Anisotropic structure of the synthesized films and dispersed MWCNT‐Cy in the films approved by use of X‐ray diffraction and field emission scanning electron microscopy. The resultant PA/MWCNT‐Cy composite films were electrically conductive, which is favorable for many practical uses. Measurements of mechanical properties of these composite films showed high strength in 8% MWCNT‐Cy content. Also, results showed increases in Young's modulus and tensile strength. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis, Characterization and Weak Intramolecular Interactions of Porphyrins Bearing Nucleobases

5,10, 15-Triphenyl-20-{2- [α- (adenine-9 ) acetylamino]} phenyl porphyrin ( 1 ), 5,10, 15-triphenyl-20-{2-[α-(cytosine-1)acetylamino]} phenyl porphyrin (2), 5, 10, 15-triphenyl-20-{4-[α-(cytosine-1)ethoxy]} phenyl porphyrin (3) and their zinc complexes Zn-1, Zn-2 and Zn-3 have been prepared and characterized by ^1H NMR spectra, elemental analyses, electronic absorption spectra and mass spectra (FAB). Intramolecular π-π interactions and intramolecular metal-~ interaction for 1, 2, Zn-1,and Zn-2 have been investigated by several methods. ^1H NMR studies demonstrate that the porphyrin π-system in 1 and 2 is parallel to the adenine and the cytosine aromatic ring, respectively. The electronic absorption spectral properties of free porphyrin derivatives and their zinc complexes have been compared with those of H2TPP and ZnTPP. The results show that the UV-vis spectra of 1 and 2 are the same as that of H2TPP,whereas the spectra of their zinc complexes show 7 nm red shifts of the Soret bands compared to that of ZnTPP. The emission spectra of Zn-1 and Zn-2 are independent of excitation wavelength. From combination of the evidence of absorption and emission spectra it is suggested the existence of intramolecular metal-π interaction in Zn-1 and Zn-2. The results of conformational analysis agreed quite nicely with that of experiments, thus it was further to validate the experimental conclusions.     

Competition between supernucleation and plasticization in the crystallization and rheological behavior of PCL/CNT‐based nanocomposites and nanohybrids

PCL was blended with pristine multiwalled carbon nanotubes (MWCNT) and with a nanohybrid obtained from the same MWCNT but grafted with low molecular weight PCL, employing concentrations of 0.25 to 5 wt % of MWCNT and MWCNT‐g‐PCL. Excellent CNT dispersion was found in all samples leading to supernucleation of both nanofiller types. Nanohybrids with 1 wt % or less MWCNTs crystallize faster than nanocomposites (due to supernucleation), while the trend eventually reverses at higher nanotubes content (because of plasticization). Rheological results show that yield‐like behavior develops in both nanocomposites, even for the minimum content of carbon nanotubes. In addition, the MWCNT‐g‐PCL family, when compared with the neat polymer, exhibits lower values of viscosity and modulus in oscillatory shear, and higher compliance in creep. These rheological differences are discussed in terms of the plasticization effect caused by the existence of low molecular weight free and grafted PCL chains in the nanohybrids. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1310–1325     

Photoinduced Charge Separation in Zinc–Porphyrin/Tungsten–Alkylidyne Dyads: Generation of Reactive Porphyrin and Metallo Radical States

The luminescent tungsten–alkylidyne metalloligand [WCl(≡C‐4,4′‐C₆H₄CC‐py)(dppe)₂] ( 1 ; dppe=1,2‐bis(diphenylphosphino)ethane) and the zinc–tetraarylporphyrins ZnTPP and ZnTP_ClP (TPP=tetraphenylporphyrin, TP_ClP=tetra(p‐chlorophenyl)porphyrin) self‐assemble in fluorobenzene solution to form the dyads ZnTPP( 1 ) and ZnTP_ClP( 1 ), in which the metalloligand is axially coordinated to the porphyrin. Excitation of the porphyrin‐centered S₁ excited states of these dyads initiates intramolecular energy‐transfer (ZnPor→ 1 ) and electron‐transfer ( 1 →ZnPor) processes, which together efficiently quench the S₁ state (～90 %). Transient‐absorption spectroscopy and an associated kinetic analysis reveal that the net product of the energy‐transfer process is the ³[dπ*] state of coordinated 1 , which is formed by S₁→¹[dπ*] singlet–singlet (Förster) energy transfer followed by ¹[dπ*]→³[dπ*] intersystem crossing. The data also demonstrate that coordinated 1 reductively quenches the porphyrin S₁ state to produce the [ZnPor^?][ 1⁺ ] charge‐separated state. This is a rare example of the reductive quenching of zinc porphyrin chromophores. The presence in the [ZnPor^?][ 1⁺ ] charge‐separated states of powerfully reducing zinc–porphyrin radical anions, which are capable of sensitizing a wide range of reductive electrocatalysts, and the 1⁺ ion, which can initiate the oxidation of H₂, produces an integrated photochemical system with the thermodynamic capability of driving photoredox processes that result in the transfer of renewable reducing equivalents instead of the consumption of conventional sacrificial donors.     

Hetero Face‐to‐Face Porphyrin Array with Cooperative Effects of Coordination and Host–Guest Complexation

We successfully synthesized a hetero face‐to‐face porphyrin array composed of ZnTPP and RuTPP(DABCO)₂ (TPP: 5, 10, 15, 20‐tetraphenylporphyrin, DABCO: 1,4‐diazabi‐cyclo[2.2.2]octane) in 2:1 molar ratio. A cyclic Zn porphyrin dimer (ZnCP) was also used as the host molecule for the Ru porphyrin. In the latter, the Ru‐DABCO bonding in RuTPP(DABCO)₂ was stabilized by the host‐guest complexation. Reaction progress kinetic analysis of the ligand substitution reaction of RuTPP(DABCO)₂ and that in ZnCP revealed the stabilization mechanism of the Ru‐DABCO bonding. Photoinduced electron transfer (PET) from the Zn porphyrin to the Ru porphyrin was observed in the porphyrin array. The host‐guest stabilization of unstable complex for construction of a donor—acceptor–donor structure is expected to be a new method for an artificial photosynthesis.     

Flexible Tuning of Unsaturated β‐Substituents on Zn Porphyrins: A Synthetic,Spectroscopic and Computational Study

A series of zinc porphyrins substituted at adjacent β‐positions with a CN group and para‐substituted ethenyl/ethynyl‐phenyl group have been studied using electronic absorption spectroscopy, resonance Raman spectroscopy and DFT calculations. The oxidative nucleophilic substitution of hydrogen was utilized for the introduction of a cyano substituent on the porphyrin ring. This modification has a remarkable electronic effect on the ring. The resulting porphyrin cyanoaldehyde was further modified in Wittig condensations to give series of arylalkene‐ and arylalkyne‐substituted derivatives. This substitution pattern caused significant redshifting and broadening of the B band, tuning from 433–446 nm. Additionally the Q/B band intensity ratios show much higher values than observed for the parent porphyrin ZnTPP (0.20 vs. 0.03). Careful analysis of the electronic transitions using DFT and resonance Raman spectroscopy reveal that the substituent does not significantly perturb the electronic structure of the porphyrin core, which is still well described by Gouterman’s four‐orbital model. However, the substituents do play a role in elongating the conjugation length and this results in the observed spectral changes.     

A Novel Procedure to Synthesize 3‐Chloro‐1‐(4a,10b‐diazaphenanthrene‐2‐yl)‐4‐phenyl Azetidin‐2‐ones and Exploration of Their Anti‐Inflammatory Activity

Some new derivatives of 3‐chloro‐1‐(4a,10b‐diazaphenanthrene‐2‐yl)‐4‐phenyl azetidin‐2‐one were synthesized through the reaction of N‐{4‐[phenyldiazenyl] phenyl}‐N‐[phenyl methylene] amine with 4‐[phenyldiazenyl] aniline. The resulting 3‐chloro‐4‐phenyl‐1‐{4‐[phenyldiazenyl] phenyl} azetidin‐2‐one intermediate in benzene was irradiated in a Pyrex vessel with 350 nm UV light in a photochemical reactor to give the desired derivatives (4a–j) . Structures of the new compounds were verified on the basis of spectral and elemental methods of analyses. Nine of the prepared compounds were tested for their anti‐inflammatory effects; most of these compounds showed potent and significant results compared with indomethacin.     

Polyelectrolyte‐Assisted Noncovalent Functionalization of Carbon Nanotubes with Ordered Self‐Assemblies of a Water‐Soluble Porphyrin

The self‐assembly and induced supramolecular chirality of meso‐tetrakis(4‐sulfonatophenyl)porphyrin (TSPP) on both single‐wall (SWCNT) and multiwall carbon nanotubes (MWCNT) are investigated. Under mild pH conditions (pH 3), TSPP forms aggregates when CNTs are dispersed in an aqueous solution containing positively charged polyelectrolytes such as poly‐L ‐lysine (PLL) or poly(allylamine hydrochloride) (PAH). Evidence for the geometry of the porphyrin aggregates is obtained from absorption spectra, whereby the fingerprints of J‐ and H‐aggregates are clearly seen only in the presence of smaller‐diameter nanotubes. J‐aggregates are better stabilized with PLL, whereas in the presence of PAH mainly H‐aggregates prevail. Excited‐state interactions within these nanohybrids are studied by steady‐state and time‐resolved fluorescence. The porphyrin emission intensity in the nanohybrid solution is significantly quenched compared to that of TSPP alone, and this implies strong electronic interaction between CNTs and porphyrin molecules. Fluorescence lifetime imaging microscopy (FLIM) further supports that porphyrin arrays are associated with the MWCNT sidewalls wrapped in PLL. In the case of the SWCNT hybrid, spherical structures associated with longer fluorescence lifetime appeared after one week, indicative of H‐aggregates of TSPP. The latter are the result of π–π stacking of porphyrin units on neighboring nanotubes facilitated by the strong tendency of these nanotubes to interact with each other. These results highlight the importance of optimum dimensions and surface‐area architectures of CNTs in the control/stability of the porphyrin aggregates with promising properties for light harvesting.     

Photodynamic Therapy of Oligoethylene Glycol‐Dendronized Reduction‐Sensitive Porphyrins

Graphene oxide (GO ) and its functionalized derivatives have attracted increasing attention in medical treatment. Herein, a reduction sensitive PEI‐GO ‐SS ‐TPP was synthesized for photodynamic therapy. More than 80% porphyrin release was observed in the presence of 10 mmol•L⁻¹ DTT in one day. The confocal laser scanning microscopy confirmed that the cell uptake efficiency of PEI‐GO‐SS‐TPP was remarkably enhanced as compared to free porphyrin which was significantly dependent on incubation time. For photodynamic therapy, GSH‐OEt could effectively increase the photodynamic therapy efficiency of PEI‐GO ‐SS ‐TPP . Compared with free porphyrin, the toxicity from PEI‐GO ‐SS ‐TPP is much higher with a low IC₅₀ (2.1 µg/mL ) value. All results indicate that the PEI‐GO ‐SS ‐TPP PSs are promising for photodynamic therapy.     

Photocatalytic Hydrogen Evolution Based on Efficient Energy and Electron Transfers in Donor–Bridge–Acceptor Multibranched‐Porphyrin‐Functionalized Platinum Nanocomposites

Two donor–bridge–acceptor conjugates (5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso‐position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched‐porphyrin‐functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light‐harvesting photosensitizer. The occurrence of photoinduced electron‐transfer processes was confirmed by time‐resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H₂, the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor–bridge–acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.     

Synthesis of Lactosylated Piperazinyl Porphyrins and Their Biological Activity

The aim of this work is to synthesize of a new family of lactosylated piperazinly porphyrins, in which the galactoside piperazine moieties are linked to the tetra‐ and mono‐phenyl rings of tetraphenylporphyrin (TPP). 5,10,15,20‐Tetrakis[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]porphyrin (TLPP) and 5‐mono[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]‐10,15,20‐triphenylporphyrin (MLPP) have been synthesized. A detailed ¹H NMR study gave their complete structural elucidation. The UV‐Visible, mass spectra and elemental analysis are also presented. The biological activity on cancer cells and the pharmacokinetics have also been evaluated, showing a better biological activity, a very high liver to skin ratio and short retention time in tissues. It was suggested that such novel lactosylated piperazinly porphyrins, as potential hepatocyte‐selective targeting drugs, exhibit a promising activity in photodynamic therapy (PDT).     

Covalent and Non‐covalent Chemical Modification of Multi‐walled Carbon Nanotubes with Tetra‐(4‐hydroxylphenyl)porphyrin and Its Complexes

Multi‐walled carbon nanotubes (MWNTs) were covalently and non‐covalently functionalized with tetra‐(4‐hydroxylphenyl) porphyrin (THPPH₂) and its complexes (ZnTHPP) forming dispersible nanohybrids in organic solution. The morphology of the nanohybrids was observed with transmission electron microscopy. The structure of the product was characterized by FT‐IR, UV‐Vis spectrophotometer, fluorescence spectroscopy and thermogravimetric analysis. The photo‐induced electron‐transfer process of the nanohybrids in organic solution was also revealed.     

Structural and morphological studies on the deformation behavior of polypropylene/multi‐walled carbon nanotubes nanocomposites prepared through ultrasound‐assisted melt extrusion process

Structural and morphological behavior under stress–strain of polypropylene/multi‐walled carbon nanotubes (PP/MWCNTs) nanocomposites prepared through ultrasound‐assisted melt extrusion process was studied by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, small angle X‐ray scattering (SAXS), and wide angle X‐ray scattering (WAXS). A high ductile behavior was observed in the PP/MWCNT nanocomposites with low concentration of MWCNTs. This was related to an energy‐dissipating mechanism, achieved by the formation of an ordered PP‐CNTs interphase zone and crystal oriented structure in the undeformed samples. Different strain‐induced‐phase transformations were observed by ex situ SAXS/WAXS, characterizing the different stages of structure development during the deformation of PP and PP/MWCNTs nanocomposites. The high concentration of CNTs reduced the strain behavior of PP due to the agglomeration of nanoparticles. A structural pathway relating the deformation‐induced phase transitions and the dissipation energy mechanism in the PP/MWCNTs nanocomposites at low concentration of nanoparticles was proposed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 475–491     

Preparation of poly(styrene‐co‐acrylonitrile)‐grafted multiwalled carbon nanotubes via surface‐initiated atom transfer radical polymerization

The in situ grafting‐from approach via atom transfer radical polymerization was successfully applied to polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile grafted onto the convex surfaces of multiwalled carbon nanotubes (MWCNTs) with (2‐hydroxyethyl 2‐bromoisobutyrate) as an initiator. Thermogravimetric analysis showed that effective functionalization was achieved with the grafting approach. The grafted polymers on the MWCNT surface were characterized and confirmed with Fourier transform infrared spectroscopy and nuclear magnetic resonance. Raman and near‐infrared spectroscopy revealed that the grafting of polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile slightly affected the side‐wall structures. Field emission scanning electron microscopy showed that the carbon nanotube surface became rough because of the grafting of the polymers. Differential scanning calorimetry results indicated that the polymers grafted onto MWCNTs showed higher glass‐transition temperatures. The polymer‐grafted MWCNTs exhibited relatively good dispersibility in an organic solvent such as tetrahydrofuran. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 460–470, 2007     

Synthesis of 4‐(1‐phenyl‐1H‐pyrazol‐3‐yl)‐[1,2,4]triazolo[4,3‐a]quinoxalines and their 4‐halogenopyrazolyl analogs

Synthesis of {3‐[1‐(ethoxycarbonyl)‐[1,2,4]triazolo[4,3‐a]quinoxalin‐4‐yl]‐1‐phenyl‐1H‐pyrazol‐5‐yl}methyl ethyl oxalate ( 2 ), ethyl 4‐[5‐(acetoxymethyl)‐1‐phenyl‐1H‐pyrazol‐3‐yl]‐[1,2,4]triazolo[4,3‐a]quioxaline‐1‐carboxylate ( 4 ), [4‐halo‐1‐phenyl‐3‐(1‐phenyl‐[1,2,4]triazolo[4,3‐a]quioxalin‐4‐yl)‐1H‐pyrazol‐5‐yl]methyl acetate ( 11 ), {4‐halo‐3‐[1‐methyl‐[1,2,4]triazolo[4,3‐a]quinoxalin‐4‐yl]‐1‐phenyl‐1H‐pyraz‐ol‐5‐yl}methyl acetate ( 13 ), and [3‐([1,2,4]triazolo‐[4,3‐a]quinoxalin‐4‐yl)‐4‐halo‐1‐phenyl‐1H‐pyrazol‐5‐yl] methyl formate ( 15 ) was accomplished. The structural investigation of the new compounds is based on chemical and spectroscopic evidences. J. Heterocyclic Chem., (2011)