Login In
2013 Volume 24 Issue 7
2013, 24(07): 545-552
Abstract:
Gold nanoparticles (AuNPs) functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins (CDs), cucurbit[n]urils (CB[n]), calix[n]arenes, and pillar[n]arenes (P[n]A). Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.
Gold nanoparticles (AuNPs) functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins (CDs), cucurbit[n]urils (CB[n]), calix[n]arenes, and pillar[n]arenes (P[n]A). Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.
2013, 24(07): 553-558
Abstract:
A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides. The hemiesters were obtained in high yield with up to 93% ee. The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X7 receptor antagonists.
A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides. The hemiesters were obtained in high yield with up to 93% ee. The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X7 receptor antagonists.
2013, 24(07): 559-562
Abstract:
Trimodal hierarchical yolk-shell materials consisting of TS-1 core and mesoporous carbon shell (YS-TS-1@MC) was successfully synthesized by using TS-1@mesosilica as hard template, sucrose as carbon source and organic base tetrapropylammonium hydroxide (TPAOH) as silica etching agent. The resultant YS-TS-1@MC contains the micropores (0.51 nm) in TS-1 core, the mesopores (2.9 nm) in carbon shell as well as a void or a stack pore between TS-1 fragements (TS-1 intercrystal mesopores, 18.4 nm). Under the rigorous etching conditions, the crystalline structure of TS-1core was well retained. The YS-TS-1@MC served as a good support for palladium nano-particles (Pd NPs) or Rh(OH)x species, giving rise to efficient bifunctional catalysts for the tandem reactions including one-pot synthesis of propylene oxide or amides.
Trimodal hierarchical yolk-shell materials consisting of TS-1 core and mesoporous carbon shell (YS-TS-1@MC) was successfully synthesized by using TS-1@mesosilica as hard template, sucrose as carbon source and organic base tetrapropylammonium hydroxide (TPAOH) as silica etching agent. The resultant YS-TS-1@MC contains the micropores (0.51 nm) in TS-1 core, the mesopores (2.9 nm) in carbon shell as well as a void or a stack pore between TS-1 fragements (TS-1 intercrystal mesopores, 18.4 nm). Under the rigorous etching conditions, the crystalline structure of TS-1core was well retained. The YS-TS-1@MC served as a good support for palladium nano-particles (Pd NPs) or Rh(OH)x species, giving rise to efficient bifunctional catalysts for the tandem reactions including one-pot synthesis of propylene oxide or amides.
2013, 24(07): 563-567
Abstract:
A [3]rotaxane 1 involving two naphtho-21-crown-7 (N21C7) rings and a dumbbell-shaped component 4 was synthesized. The dumbbell-shape molecule 4 contains one viologen nucleus, two secondary alkyl ammonium sites and two phenyl stoppers. After threading the N21C7 ring with the thread-like ammonium guest 3, the copper(I)-catalyzed Huisgen alkyne-azide 1,3-dipolar cycloaddition (CuAAC "click" reaction), was performed to connect the pseudorotaxanes with viologen unit 2 and generate 1. Through treating the [3]rotaxane by the base and acid circularly, the two N21C7 rings can make shuttling motion along the axle. Meanwhile the distance between the electron-deficient viologen unit and the electron-rich naphthol group can be adjusted precisely along with a remarkable intramolecular chargetransfer (CT) behavior.
A [3]rotaxane 1 involving two naphtho-21-crown-7 (N21C7) rings and a dumbbell-shaped component 4 was synthesized. The dumbbell-shape molecule 4 contains one viologen nucleus, two secondary alkyl ammonium sites and two phenyl stoppers. After threading the N21C7 ring with the thread-like ammonium guest 3, the copper(I)-catalyzed Huisgen alkyne-azide 1,3-dipolar cycloaddition (CuAAC "click" reaction), was performed to connect the pseudorotaxanes with viologen unit 2 and generate 1. Through treating the [3]rotaxane by the base and acid circularly, the two N21C7 rings can make shuttling motion along the axle. Meanwhile the distance between the electron-deficient viologen unit and the electron-rich naphthol group can be adjusted precisely along with a remarkable intramolecular chargetransfer (CT) behavior.
2013, 24(07): 568-572
Abstract:
A novel supramolecular graft copolymer (SGP) composed of viologen-containing copolymer (P(DMA-co-diEV)) as the main chain and Np ended PNIPAM (Np-PNIPAm) as the grafts is prepared (DMA: N,N-dimethylacryamide, diEV: ethylviologen dimer, Np: naphthalene, PNIPAM: poly(N-isopropylacrylamide)). The grafting is based on the triple complexation among a host of cucurbit[8]uril (CB[8]) and two guests of diEV and Np, which is characterized by UV-vis spectra and ITC. Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle (NCCM) at high temperature. The micelles are sensitive to reducing agents, for example Na2S2O3, which breaks the current inclusion complex pair and induces aggregation.
A novel supramolecular graft copolymer (SGP) composed of viologen-containing copolymer (P(DMA-co-diEV)) as the main chain and Np ended PNIPAM (Np-PNIPAm) as the grafts is prepared (DMA: N,N-dimethylacryamide, diEV: ethylviologen dimer, Np: naphthalene, PNIPAM: poly(N-isopropylacrylamide)). The grafting is based on the triple complexation among a host of cucurbit[8]uril (CB[8]) and two guests of diEV and Np, which is characterized by UV-vis spectra and ITC. Temperature sensitive property of PNIPAm moiety allows SGP to self-assemble into non-covalently connected micelle (NCCM) at high temperature. The micelles are sensitive to reducing agents, for example Na2S2O3, which breaks the current inclusion complex pair and induces aggregation.
2013, 24(07): 573-577
Abstract:
Two tetrathiafulvalene-calix[4]arene assemblies (TTF-calix-1 and TTF-calix-2) have been synthesized by the click reaction. Both their cyclic voltammograms show, as expected, two one-electron quasi-reversible redox behavior. The UV-vis absorption spectra studies show that these two assemblies undergo progressive oxidation at the TTF moiety in presence of increasing amounts of Cu2+ or Hg2+. Moreover, the absorption studies show intermolecular electron transfer between compounds TTF-calix-1 or TTF-calix-2 and p-chloranil may be promoted by specific metal ions such as Pb2+, Sc3+ etc.
Two tetrathiafulvalene-calix[4]arene assemblies (TTF-calix-1 and TTF-calix-2) have been synthesized by the click reaction. Both their cyclic voltammograms show, as expected, two one-electron quasi-reversible redox behavior. The UV-vis absorption spectra studies show that these two assemblies undergo progressive oxidation at the TTF moiety in presence of increasing amounts of Cu2+ or Hg2+. Moreover, the absorption studies show intermolecular electron transfer between compounds TTF-calix-1 or TTF-calix-2 and p-chloranil may be promoted by specific metal ions such as Pb2+, Sc3+ etc.
2013, 24(07): 578-580
Abstract:
An assembly of Keggin polyoxomolybdate and organic substrate (Hbipy)3[PMo12O40] (1, bipy=2,2'-bipyridine) was synthesized and characterized by elemental analysis, infrared spectrum, and singlecrystal X-ray analysis. The ligand bipy of compound 1 was generated by a decarboxylation coupling reaction of H2pdc (H2pdc=pyridine-2,6-dicarboxylic acid) in situ under hydrothermal reaction conditions and the control experiments illustrate that La(NO3)3 or Ce(NO3)3, which does not appear in the final structure, is necessary for the decarboxylation coupling reaction. Moreover, compound 1 displays strong photoluminescence property in the solid state at room temperature.
An assembly of Keggin polyoxomolybdate and organic substrate (Hbipy)3[PMo12O40] (1, bipy=2,2'-bipyridine) was synthesized and characterized by elemental analysis, infrared spectrum, and singlecrystal X-ray analysis. The ligand bipy of compound 1 was generated by a decarboxylation coupling reaction of H2pdc (H2pdc=pyridine-2,6-dicarboxylic acid) in situ under hydrothermal reaction conditions and the control experiments illustrate that La(NO3)3 or Ce(NO3)3, which does not appear in the final structure, is necessary for the decarboxylation coupling reaction. Moreover, compound 1 displays strong photoluminescence property in the solid state at room temperature.
2013, 24(07): 581-584
Abstract:
A {Ni7} cluster-substituted sandwich-type phosphotungstate Na10(NH4)4[{(B-a-PW9O34)Ni4 (OH)(H2O)2(HAle)}2Ni]·22H2O (1) was synthesized using the conventional aqueous solution method. Compound 1 represents the first nickel-containing sandwich-type polyoxometalate functionalized by bisphosphonate ligands. Further, the sandwich-type polyoxoanions aggregated via the H-bonding interactions into a two-dimensional (2D) supramolecular framework.
A {Ni7} cluster-substituted sandwich-type phosphotungstate Na10(NH4)4[{(B-a-PW9O34)Ni4 (OH)(H2O)2(HAle)}2Ni]·22H2O (1) was synthesized using the conventional aqueous solution method. Compound 1 represents the first nickel-containing sandwich-type polyoxometalate functionalized by bisphosphonate ligands. Further, the sandwich-type polyoxoanions aggregated via the H-bonding interactions into a two-dimensional (2D) supramolecular framework.
2013, 24(07): 585-587
Abstract:
The in vitro digestibility of alcalase enzymatic hydrolysates of β-conglycinin was studied. The results showed that the zeta potentials of β-conglycinin hydrolysates decreased and their electronegativity increased when digested with pepsin and trypsin. Furthermore, the content of peptides with molecular weight from 10 kDa to 20 kDa remained stable, while those with higher molecular weight (>20 kDa) decreased, and those with lower molecular weight (<10 kDa) increased. The proportion of highly hydrophobic peptides decreased in the process of the in vitro digestion, but no significant change in the surface hydrophobicity indices of digestion products was observed (P < 0.05). These results indicate that the β-conglycinin hydrolysates were degraded through in vitro digestion, but the degree of degradation was relatively low. Peptides with molecular weight from 10 kDa to 20 kDa in the β-conglycinin hydrolysates resisted the digestion by pepsin and trypsin and they remained stable during the in vitro digestion processes.
The in vitro digestibility of alcalase enzymatic hydrolysates of β-conglycinin was studied. The results showed that the zeta potentials of β-conglycinin hydrolysates decreased and their electronegativity increased when digested with pepsin and trypsin. Furthermore, the content of peptides with molecular weight from 10 kDa to 20 kDa remained stable, while those with higher molecular weight (>20 kDa) decreased, and those with lower molecular weight (<10 kDa) increased. The proportion of highly hydrophobic peptides decreased in the process of the in vitro digestion, but no significant change in the surface hydrophobicity indices of digestion products was observed (P < 0.05). These results indicate that the β-conglycinin hydrolysates were degraded through in vitro digestion, but the degree of degradation was relatively low. Peptides with molecular weight from 10 kDa to 20 kDa in the β-conglycinin hydrolysates resisted the digestion by pepsin and trypsin and they remained stable during the in vitro digestion processes.
2013, 24(07): 588-592
Abstract:
In this work, a new sample pretreatment method prior to HPLC separations was developed for the determination of auxins in plant samples. Owing to its large surface area and high adsorption capacity, multi-walled carbon nanotube (MWCNT) was chosen as the adsorbent for the extraction of auxins from plant samples. In this study, two important auxins were selected as model analytes, namely indole-3-butyric acid (IBA) and 1-naphthylacetic acid (NAA). They could be extracted and concentrated due to their π-π stacking interactions with MWCNT. Then HPLC-UV was introduced to detect IBA and NAA after sample pretreatment. Factors that may affect the enrichment efficiency were investigated and optimized. Comparative studies showed that MWCNT was superior to C18 for the extraction of the two analytes. Validation experiments showed that the optimized method had good linearity (0.9998 and 0.9960), high recovery (81.4%-85.4%), and low detection limits (0.0030 mg/L and 0.0012 mg/L). The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it was feasible for the determination of auxins in plant samples.
In this work, a new sample pretreatment method prior to HPLC separations was developed for the determination of auxins in plant samples. Owing to its large surface area and high adsorption capacity, multi-walled carbon nanotube (MWCNT) was chosen as the adsorbent for the extraction of auxins from plant samples. In this study, two important auxins were selected as model analytes, namely indole-3-butyric acid (IBA) and 1-naphthylacetic acid (NAA). They could be extracted and concentrated due to their π-π stacking interactions with MWCNT. Then HPLC-UV was introduced to detect IBA and NAA after sample pretreatment. Factors that may affect the enrichment efficiency were investigated and optimized. Comparative studies showed that MWCNT was superior to C18 for the extraction of the two analytes. Validation experiments showed that the optimized method had good linearity (0.9998 and 0.9960), high recovery (81.4%-85.4%), and low detection limits (0.0030 mg/L and 0.0012 mg/L). The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it was feasible for the determination of auxins in plant samples.
2013, 24(07): 593-596
Abstract:
Four Cu2+ complexes of salicylidene-amino acid Schiff base with 1,10-phenanthroline (Phen) or 2,2'-bipyridine (Bipy) were successfully intercalated in interlayer galleries of Mg/Al-NO3-layered double hydroxide (LDH) by the swelling-restored method. The hybrids were characterized by elemental analysis, X-ray diffraction, FT-IR spectra, UV-vis DRS, TG-DTA and SEM observation. Good protection of the complexes by LDH in neutral and weak acidic solutions was revealed by UV spectra, cyclic voltammograms and luminescence spectra.
Four Cu2+ complexes of salicylidene-amino acid Schiff base with 1,10-phenanthroline (Phen) or 2,2'-bipyridine (Bipy) were successfully intercalated in interlayer galleries of Mg/Al-NO3-layered double hydroxide (LDH) by the swelling-restored method. The hybrids were characterized by elemental analysis, X-ray diffraction, FT-IR spectra, UV-vis DRS, TG-DTA and SEM observation. Good protection of the complexes by LDH in neutral and weak acidic solutions was revealed by UV spectra, cyclic voltammograms and luminescence spectra.
2013, 24(07): 597-600
Abstract:
A novel polydopamine-graft-poly(2-methyl-2-oxazoline) (PDA-g-PMOXA) coating was prepared by immobilizing poly(2-methyl-2-oxazoline) (PMOXA) onto material surfaces through polydopamine (PDA) anchored coating for the first time. And then, the chemical composition, hydrophilicity, and protein-resistant properties of the PDA-g-PMOXA coating were studied using X-ray photoelectron spectroscopy (XPS), contact angel (CA) test, surface plasmon resonance (SPR), and quartz crystal microbalance with dissipation (QCM-D) measurement. Finally, the coating was applied to the capillary inner surface for protein separation by capillary electrophoresis (CE).
A novel polydopamine-graft-poly(2-methyl-2-oxazoline) (PDA-g-PMOXA) coating was prepared by immobilizing poly(2-methyl-2-oxazoline) (PMOXA) onto material surfaces through polydopamine (PDA) anchored coating for the first time. And then, the chemical composition, hydrophilicity, and protein-resistant properties of the PDA-g-PMOXA coating were studied using X-ray photoelectron spectroscopy (XPS), contact angel (CA) test, surface plasmon resonance (SPR), and quartz crystal microbalance with dissipation (QCM-D) measurement. Finally, the coating was applied to the capillary inner surface for protein separation by capillary electrophoresis (CE).
2013, 24(07): 601-604
Abstract:
A novel, bifunctional, hypercrosslinked, magnetic resin W2 was prepared using divinylbenzene (DVB) and glycidyl methacrylate (GMA) as comonomers in three steps (i.e., suspension polymerization, amination and post-crosslinking reactions). To evaluate the adsorption of natural organic matter (NOM) and organic micropollutants (OMPs) on the obtained resin W2, two magnetic resins W1(the precursor of W2 before post-crosslinking) and W0 (the precursor of W1 before amination) were chosen for comparison. The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.
A novel, bifunctional, hypercrosslinked, magnetic resin W2 was prepared using divinylbenzene (DVB) and glycidyl methacrylate (GMA) as comonomers in three steps (i.e., suspension polymerization, amination and post-crosslinking reactions). To evaluate the adsorption of natural organic matter (NOM) and organic micropollutants (OMPs) on the obtained resin W2, two magnetic resins W1(the precursor of W2 before post-crosslinking) and W0 (the precursor of W1 before amination) were chosen for comparison. The results indicated that W2 would be a promising material for the removal of both NOM and OMPs from aquatic environments.
2013, 24(07): 605-608
Abstract:
Tetrabutylammonium fluoride (TBAF) effectively facilitated a denitrative substitution reaction of electron-deficient nitroarenes with phenylthiotrimethylsilane (PhSTMS) under mild and base-free neutral conditions at room temperature, providing a practical and efficient synthesis of useful unsymmetrical diaryl thioethers. Nitroarenes bearing ortho-and para-positioned electron-withdrawing groups are the most reactive substrates, indicating that this reaction most possibly proceeded via the nucleophilic aromatic substitution (SNAr) mechanism.
Tetrabutylammonium fluoride (TBAF) effectively facilitated a denitrative substitution reaction of electron-deficient nitroarenes with phenylthiotrimethylsilane (PhSTMS) under mild and base-free neutral conditions at room temperature, providing a practical and efficient synthesis of useful unsymmetrical diaryl thioethers. Nitroarenes bearing ortho-and para-positioned electron-withdrawing groups are the most reactive substrates, indicating that this reaction most possibly proceeded via the nucleophilic aromatic substitution (SNAr) mechanism.
2013, 24(07): 609-612
Abstract:
Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone (L1-L4) have been synthesized and their Cu(Ⅱ) complexes (1-4) were afforded via coordination with cupric chloride. All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis. NMR spectroscopy was also applied to characterize the ligands. In vitro cholinesterase inhibitory assays for the complexes (1-4) showed IC50 values less than 10 μmol/L, with complex 1 exhibiting the most activity, IC50=2.15 μmol/L and 2.16 μmol/L for AChE and BuChE, respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors. In DPPH assay, the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.
Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone (L1-L4) have been synthesized and their Cu(Ⅱ) complexes (1-4) were afforded via coordination with cupric chloride. All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis. NMR spectroscopy was also applied to characterize the ligands. In vitro cholinesterase inhibitory assays for the complexes (1-4) showed IC50 values less than 10 μmol/L, with complex 1 exhibiting the most activity, IC50=2.15 μmol/L and 2.16 μmol/L for AChE and BuChE, respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors. In DPPH assay, the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.
2013, 24(07): 613-616
Abstract:
An unusual substitution reaction of an aromatic sulfonic group based on 3-carbonyl-4-phenolsulfonic acid was discovered in a diazo-coupling process. The reaction occurred under mild reaction conditions (pH 8.0-9.0, 0-5℃, solvent: water) within a short reaction time (1 h). A plausible substitution reaction mechanism by phenol-ketone resonance was proposed.
An unusual substitution reaction of an aromatic sulfonic group based on 3-carbonyl-4-phenolsulfonic acid was discovered in a diazo-coupling process. The reaction occurred under mild reaction conditions (pH 8.0-9.0, 0-5℃, solvent: water) within a short reaction time (1 h). A plausible substitution reaction mechanism by phenol-ketone resonance was proposed.
2013, 24(07): 617-618
Abstract:
2β,3α-Dihydroxyurs-12-en-28-oic acid (6) is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi-synthesis of 6 was developed. Using the commercially available ursolic acid (1) as the starting materials, 6 was synthesized through five facile reactions with a high stereoselectivity and an overall yield of 47.3%. The structure of 6 was confirmed by optical rotation, ESI-MS, 1H NMR and 13C NMR data.
2β,3α-Dihydroxyurs-12-en-28-oic acid (6) is a naturally occurring diastereoisomer of corosolic acid with glycogen phosphorylase inhibitory activity. A new strategy for the semi-synthesis of 6 was developed. Using the commercially available ursolic acid (1) as the starting materials, 6 was synthesized through five facile reactions with a high stereoselectivity and an overall yield of 47.3%. The structure of 6 was confirmed by optical rotation, ESI-MS, 1H NMR and 13C NMR data.
Synthesis and biological evaluation of new pyrrolopyrazinone compounds as potential antitumor agents
2013, 24(07): 619-621
Abstract:
A series of pyrrolo[1,2-a]pyrazinone compounds (5a-9f) were synthesized, and their cytotoxic activity against SKOV-3, A549, HeLa cells in vitro were evaluated by the MTT method. Some of the compounds showed potential antitumor activity against three tumor cell lines. Among them, compounds 9c and 9d showed the most potent cytotoxic activity. The preliminary mechanism of action was discussed.
A series of pyrrolo[1,2-a]pyrazinone compounds (5a-9f) were synthesized, and their cytotoxic activity against SKOV-3, A549, HeLa cells in vitro were evaluated by the MTT method. Some of the compounds showed potential antitumor activity against three tumor cell lines. Among them, compounds 9c and 9d showed the most potent cytotoxic activity. The preliminary mechanism of action was discussed.
2013, 24(07): 622-624
Abstract:
An efficient and mild synthesis of 2-(guaiazulen-1-yl)furans, starting from easily accessible 1-(3-aryl-2-cyanopropenoyl)guaiazulenes, tributylphosphine and acyl chlorides, is described. The strategy employs the intramolecular Wittig protocol as a key step to append the crucial furan ring, leading to the highly functional furans in good yields.
An efficient and mild synthesis of 2-(guaiazulen-1-yl)furans, starting from easily accessible 1-(3-aryl-2-cyanopropenoyl)guaiazulenes, tributylphosphine and acyl chlorides, is described. The strategy employs the intramolecular Wittig protocol as a key step to append the crucial furan ring, leading to the highly functional furans in good yields.
2013, 24(07): 625-628
Abstract:
A series of novel 2-(5-substituted-[1,3,4]oxadiazol-2-yl)-benzoxazoles (7a-h) were synthesized in good yields in two different directions by involving benzoxazole-2-carboxylic acid (1) as raw material and benzoxazole-2-carbonyl chloride (2), benzoxazole-2-carboxylic acid methyl ester (3), benzoxazole-2-carboxylic acid hydrazide (4), benzoxazole-2-carboxylic acid N'-acetyl hydrazide (5a-d) and benzoxazole-2-carboxylic acid-ethylidene-hydrazides (6a-d) as reactive intermediates. The chemical structures of all the synthesized compounds were elucidated by their IR, 1H NMR and 13C NMR and mass spectral data. Further, the target compounds were screened for their antimicrobial activity against various Gram-positive and Gram-negative bacteria.
A series of novel 2-(5-substituted-[1,3,4]oxadiazol-2-yl)-benzoxazoles (7a-h) were synthesized in good yields in two different directions by involving benzoxazole-2-carboxylic acid (1) as raw material and benzoxazole-2-carbonyl chloride (2), benzoxazole-2-carboxylic acid methyl ester (3), benzoxazole-2-carboxylic acid hydrazide (4), benzoxazole-2-carboxylic acid N'-acetyl hydrazide (5a-d) and benzoxazole-2-carboxylic acid-ethylidene-hydrazides (6a-d) as reactive intermediates. The chemical structures of all the synthesized compounds were elucidated by their IR, 1H NMR and 13C NMR and mass spectral data. Further, the target compounds were screened for their antimicrobial activity against various Gram-positive and Gram-negative bacteria.
2013, 24(07): 629-632
Abstract:
In this work 4-amino-6-aryl-2-phenyl pyrimidine-5-carbonitrile derivatives were synthesized through a one-pot, three-component reaction of an aldehyde, malononitrile and benzamidine hydrochloride, in the presence of magnetic nano Fe3O4 particles as a catalyst under solvent-free conditions. 3-Amino-6-aryl-2-phenylpyrazolo[3,4-d]pyrimidine derivatives were prepared through an efficient and environmentally friendly reaction between 4-amino-6-aryl-2-phenylpyrimidine-5-carbonitrile derivatives and hydrazine hydrate and their antibacterial activity has been evaluated.
In this work 4-amino-6-aryl-2-phenyl pyrimidine-5-carbonitrile derivatives were synthesized through a one-pot, three-component reaction of an aldehyde, malononitrile and benzamidine hydrochloride, in the presence of magnetic nano Fe3O4 particles as a catalyst under solvent-free conditions. 3-Amino-6-aryl-2-phenylpyrazolo[3,4-d]pyrimidine derivatives were prepared through an efficient and environmentally friendly reaction between 4-amino-6-aryl-2-phenylpyrimidine-5-carbonitrile derivatives and hydrazine hydrate and their antibacterial activity has been evaluated.
2013, 24(07): 633-635
Abstract:
In this paper, separation of Sr from associated elements (Na, K, Ca, Mg, and Ba) was carried out using an extraction chromatographic column packed with Sr selective specific resin consisting of an octanol solution of 4,4'(5')-bis(t-butylcyclohexo)-18-crown-6 sorbed on an inert polymeric support. Using 8.0 mol/L HNO3 as the eluent, Ba and associated elements were eluted immediately from the column, whereas Sr was strongly retained. The adsorbed Sr could then be stripped from the column as the eluent was changed to 0.05 mol/L HNO3. Complete Sr/Ba separation was demonstrated to be feasible in that Ba could be washed from the column leaving pure Sr by adequate rinsing with 8.0 mol/L HNO3. Furthermore, matrix effect could be effectively eliminated and the selectivity of the method was improved. The method was applied for the determination of Sr in the high purity barium carbonate (BaCO3) product and seawater. The recoveries of Sr in 2 samples were determined to be 93.2% and 109%, respectively.
In this paper, separation of Sr from associated elements (Na, K, Ca, Mg, and Ba) was carried out using an extraction chromatographic column packed with Sr selective specific resin consisting of an octanol solution of 4,4'(5')-bis(t-butylcyclohexo)-18-crown-6 sorbed on an inert polymeric support. Using 8.0 mol/L HNO3 as the eluent, Ba and associated elements were eluted immediately from the column, whereas Sr was strongly retained. The adsorbed Sr could then be stripped from the column as the eluent was changed to 0.05 mol/L HNO3. Complete Sr/Ba separation was demonstrated to be feasible in that Ba could be washed from the column leaving pure Sr by adequate rinsing with 8.0 mol/L HNO3. Furthermore, matrix effect could be effectively eliminated and the selectivity of the method was improved. The method was applied for the determination of Sr in the high purity barium carbonate (BaCO3) product and seawater. The recoveries of Sr in 2 samples were determined to be 93.2% and 109%, respectively.
2013, 24(07): 636-638
Abstract:
A sensitive method for simultaneous determination of six phenolic whitening agents, including arbutin, phenol, resorcinol, hydroquinone, kojic acid, and salicylic acid in cosmetics has been developed using micellar electrokinetic capillary chromatography with amperometric detection (MECC-AD). Effects of several factors, such as the pH value and concentration of running buffer, potential applied to the working electrode, separation voltage, and injection time were investigated to obtain optimum conditions for separation and detection. With a 75 cm long fused-silica capillary tube, well-defined separation of six phenolic compounds was achieved in 10 mmol/L SDS/40 mmol/L H3BO3-Na2B4O7 running buffer (pH 9.0). Good linear relationship was obtained for each analyte over three orders of magnitude with correlation coefficients (r2) between 0.9985 and 0.9994, and the detection limit (S/N=3) ranged from 0.04 μg/mL to 0.45 μg/mL. The proposed method has been successfully applied for the determination of phenolic whitening agents in real cosmetic samples with satisfactory results, providing an alternative monitoring method for cosmetics safety regulation.
A sensitive method for simultaneous determination of six phenolic whitening agents, including arbutin, phenol, resorcinol, hydroquinone, kojic acid, and salicylic acid in cosmetics has been developed using micellar electrokinetic capillary chromatography with amperometric detection (MECC-AD). Effects of several factors, such as the pH value and concentration of running buffer, potential applied to the working electrode, separation voltage, and injection time were investigated to obtain optimum conditions for separation and detection. With a 75 cm long fused-silica capillary tube, well-defined separation of six phenolic compounds was achieved in 10 mmol/L SDS/40 mmol/L H3BO3-Na2B4O7 running buffer (pH 9.0). Good linear relationship was obtained for each analyte over three orders of magnitude with correlation coefficients (r2) between 0.9985 and 0.9994, and the detection limit (S/N=3) ranged from 0.04 μg/mL to 0.45 μg/mL. The proposed method has been successfully applied for the determination of phenolic whitening agents in real cosmetic samples with satisfactory results, providing an alternative monitoring method for cosmetics safety regulation.
2013, 24(07): 639-642
Abstract:
Rapid and sensitive recognition of herbal pieces according to different concocted processing is crucial to quality control and pharmaceutical effect. Near-infrared (NIR) and mid-infrared (MIR) technology combined with supervised pattern recognition based on partial least-squares discriminant analysis (PLSDA) was attempted to classify and recognize six different concocted processing pieces of 600 Areca catechu L. samples and the influence of fingerprint information preprocessing methods on recognition performance was also investigated in this work. Recognition rates of 99.24%, 100% and 99.49% for original fingerprint, multiple scatter correct (MSC) fingerprint and second derivative (2nd derivative) fingerprint of NIR spectra were achieved by PLSDA models, respectively. Meanwhile, a perfect recognition rate of 100% was obtained for the above three fingerprint models of MIR spectra. In conclusion, PLSDA can rapidly and effectively extract otherness of fingerprint information from NIR and MIR spectra to identify different concocted herbal pieces of A. catechu.
Rapid and sensitive recognition of herbal pieces according to different concocted processing is crucial to quality control and pharmaceutical effect. Near-infrared (NIR) and mid-infrared (MIR) technology combined with supervised pattern recognition based on partial least-squares discriminant analysis (PLSDA) was attempted to classify and recognize six different concocted processing pieces of 600 Areca catechu L. samples and the influence of fingerprint information preprocessing methods on recognition performance was also investigated in this work. Recognition rates of 99.24%, 100% and 99.49% for original fingerprint, multiple scatter correct (MSC) fingerprint and second derivative (2nd derivative) fingerprint of NIR spectra were achieved by PLSDA models, respectively. Meanwhile, a perfect recognition rate of 100% was obtained for the above three fingerprint models of MIR spectra. In conclusion, PLSDA can rapidly and effectively extract otherness of fingerprint information from NIR and MIR spectra to identify different concocted herbal pieces of A. catechu.
2013, 24(07): 643-646
Abstract:
We report the first use of organic semiconductors (OSCs)-coated PAN nanofibrous mats as highly responsive fluorescence quenching-based chemosensors for 2,4,6-trinitrotoluene (TNT) and H2O2 detection in vapor phase. Conjugated polymers, poly(triphenylaminealt-biphenylene vinylene) (TPAPBPV), and small organic molecules, 1-boronic-ester pyrene and 1,6-bisboron-ester pyrene, were coated onto the nanofibers fabricated by electrospinning. By introducing the nanofibers structure, a 9-fold fluorescence intensity enhancement and a 14-fold sensitivity enhancement were achieved, which could be attributed to its high area-to-volume ratio, excellent gas permeability, and more importantly, the evanescent-wave effect occurred once the diameters of the fibers were small enough. Since the organic semiconductors coated onto the nanofibrous mats could be replaced by other functional materials, the nanofibers-enhanced detection strategies could be extended to more general domains including chemical and environmental detection.
We report the first use of organic semiconductors (OSCs)-coated PAN nanofibrous mats as highly responsive fluorescence quenching-based chemosensors for 2,4,6-trinitrotoluene (TNT) and H2O2 detection in vapor phase. Conjugated polymers, poly(triphenylaminealt-biphenylene vinylene) (TPAPBPV), and small organic molecules, 1-boronic-ester pyrene and 1,6-bisboron-ester pyrene, were coated onto the nanofibers fabricated by electrospinning. By introducing the nanofibers structure, a 9-fold fluorescence intensity enhancement and a 14-fold sensitivity enhancement were achieved, which could be attributed to its high area-to-volume ratio, excellent gas permeability, and more importantly, the evanescent-wave effect occurred once the diameters of the fibers were small enough. Since the organic semiconductors coated onto the nanofibrous mats could be replaced by other functional materials, the nanofibers-enhanced detection strategies could be extended to more general domains including chemical and environmental detection.
2013, 24(07): 647-650
Abstract:
Traditional modifications to hydroxyapatite (HA) nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration. In this study, a new heterofunctional poly(ethylene glycol) (PEG) with phosphoric acid and carboxyl end groups, i.e., α-(N-2-phosphoethyl phosphoric acid)-amide, ω-carboxyl-bismethyoxy poly(ethylene glycol) (ADP-PEG-COOH), was synthesized as an in situ surface modifier to HA nanoparticles. The resulting modified HA (ADP-PEG-HA) can disperse in methanol, forming a colloid stabilized by peripheral carboxyl-endcapped PEG chains. The colloidal particles resembled nanospheres which agglomerated to some extent under examination by transmission electron microscope. This highly dispersible HA nanoparticles in organic solvent might find application in preparing new HA nanocomposites.
Traditional modifications to hydroxyapatite (HA) nanoparticles usually occurred after HA synthesis and thus are insufficient to avoid particle agglomeration. In this study, a new heterofunctional poly(ethylene glycol) (PEG) with phosphoric acid and carboxyl end groups, i.e., α-(N-2-phosphoethyl phosphoric acid)-amide, ω-carboxyl-bismethyoxy poly(ethylene glycol) (ADP-PEG-COOH), was synthesized as an in situ surface modifier to HA nanoparticles. The resulting modified HA (ADP-PEG-HA) can disperse in methanol, forming a colloid stabilized by peripheral carboxyl-endcapped PEG chains. The colloidal particles resembled nanospheres which agglomerated to some extent under examination by transmission electron microscope. This highly dispersible HA nanoparticles in organic solvent might find application in preparing new HA nanocomposites.
2013, 24(07): 651-653
Abstract:
Interaction of straight chain alcohol vapors with MOF-199-functionalized films was studied by SPR. The signals had linear relationships with the concentration of alcohols over a wide range from 0 to 70% (v/v) and were reversible in proportional to the chain length, with R2 all above 0.99.
Interaction of straight chain alcohol vapors with MOF-199-functionalized films was studied by SPR. The signals had linear relationships with the concentration of alcohols over a wide range from 0 to 70% (v/v) and were reversible in proportional to the chain length, with R2 all above 0.99.
2013, 24(07): 654-658
Abstract:
Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. The results showed that incorporation of Nylon 66 into hydrogenated dimer acid-based Nylon had no significant effect on the glass transition or melting temperatures. However, the crystallization temperature, crystallinity degree and the maximum rate of decomposition temperature from derivative thermogravimetry measurements vary. Mechanical testing data revealed that with increasing Nylon 66 concentrations, the tensile strength of copolymers increased, while the elongation at break point and notched izod impact strength decreased. The physical and mechanical properties of HN-40, HN-50 and HN-60 are similar to those of the current PA11, PA1212, and PA1111 Nylon products.
Hydrogenated dimer acid-based Nylon 636/Nylon 66 copolymers were synthesized by in situ polymerization. The effects of Nylon 66 contents on the copolymers were characterized by intrinsic viscosity measurements, attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and mechanical tests. The results showed that incorporation of Nylon 66 into hydrogenated dimer acid-based Nylon had no significant effect on the glass transition or melting temperatures. However, the crystallization temperature, crystallinity degree and the maximum rate of decomposition temperature from derivative thermogravimetry measurements vary. Mechanical testing data revealed that with increasing Nylon 66 concentrations, the tensile strength of copolymers increased, while the elongation at break point and notched izod impact strength decreased. The physical and mechanical properties of HN-40, HN-50 and HN-60 are similar to those of the current PA11, PA1212, and PA1111 Nylon products.
2013, 24(07): 659-662
Abstract:
Bovine serum albumin (BSA) was modified through a facile synthesis method to increase its isoelectric point (pI) from 4.8 to 6.0. When pH is higher than 6.0, the protein shows a negative surface charge, on the contrary, the protein is positively charged. In this study, the charge-reversal modified BSA (crBSA) was utilized to assemble with the binary complexes of pDNA/poly(vinylpyrrolidone)-graft-poly(2-dimethylaminoethyl methacrylate) (pDNA/PVP-g-PDMAEMA) to shield the excess positive charges of complexes at physiological pH (pH 7.4). When the complex coated with crBSA located in the environment at endosomal pH (pH 5.0), the charge-reversal of crBSA led to the deviation of crBSA from polyplex by electrostatic repulsion, which would benefit the transfection of the target gene. The crBSA shows great potential for improving the transfection efficiency of pDNA/PVP-g-PDMAEMA.
Bovine serum albumin (BSA) was modified through a facile synthesis method to increase its isoelectric point (pI) from 4.8 to 6.0. When pH is higher than 6.0, the protein shows a negative surface charge, on the contrary, the protein is positively charged. In this study, the charge-reversal modified BSA (crBSA) was utilized to assemble with the binary complexes of pDNA/poly(vinylpyrrolidone)-graft-poly(2-dimethylaminoethyl methacrylate) (pDNA/PVP-g-PDMAEMA) to shield the excess positive charges of complexes at physiological pH (pH 7.4). When the complex coated with crBSA located in the environment at endosomal pH (pH 5.0), the charge-reversal of crBSA led to the deviation of crBSA from polyplex by electrostatic repulsion, which would benefit the transfection of the target gene. The crBSA shows great potential for improving the transfection efficiency of pDNA/PVP-g-PDMAEMA.
