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2015 Volume 26 Issue 2
2015, 26(2): 167-172
doi: 10.1016/j.cclet.2014.10.006
Abstract:
Recent noteworthy developments in the field of two-dimensional (2D) correlation spectroscopy are reviewed. 2D correlation spectroscopy has become a very popular tool due to its versatility and relative ease of use. The technique utilizes a spectroscopic or other analytical probe from a number of selections for a broad range of sample systems by employing different types of external perturbations to induce systematic variations in intensities of spectra. Such spectral intensity variations are then converted into 2D spectra by a form of correlation analysis for subsequent interpretation. Many different types of 2D correlation approaches have been proposed. In particular, 2D hetero-correlation and multiple perturbation correlation analyses, including orthogonal sample design scheme, are discussed in this review. Additional references to other important developments in the field of 2D correlation spectroscopy, such as projection correlation and codistribution analysis, were also provided.
Recent noteworthy developments in the field of two-dimensional (2D) correlation spectroscopy are reviewed. 2D correlation spectroscopy has become a very popular tool due to its versatility and relative ease of use. The technique utilizes a spectroscopic or other analytical probe from a number of selections for a broad range of sample systems by employing different types of external perturbations to induce systematic variations in intensities of spectra. Such spectral intensity variations are then converted into 2D spectra by a form of correlation analysis for subsequent interpretation. Many different types of 2D correlation approaches have been proposed. In particular, 2D hetero-correlation and multiple perturbation correlation analyses, including orthogonal sample design scheme, are discussed in this review. Additional references to other important developments in the field of 2D correlation spectroscopy, such as projection correlation and codistribution analysis, were also provided.
2015, 26(2): 173-176
doi: 10.1016/j.cclet.2014.12.012
Abstract:
This paper reports the pH-induced structural changes in the surface immobilized poly(L-lysine) (PLL) film. Two-dimensional (2D) correlation analysis was applied to the Fourier transform infrared (FTIR) spectra of the surface-immobilized PLL filmto examine the spectral changes induced by the alternations of the protonation state of the amino group in the side chain. Significant spectral changes in the FTIR spectra of the PLL film were observed between pH 7 and 8. The decrease in the protonation state of the amino group in the side chain induced spectral changes in the amino group as well as conformational changes in the alkyl group in the side chain. From pH 1-8, the spectral changes in the amino and alkyl groups in the side chain occurred before those of the amide group in the main chain of the surface immobilized PLL film.
This paper reports the pH-induced structural changes in the surface immobilized poly(L-lysine) (PLL) film. Two-dimensional (2D) correlation analysis was applied to the Fourier transform infrared (FTIR) spectra of the surface-immobilized PLL filmto examine the spectral changes induced by the alternations of the protonation state of the amino group in the side chain. Significant spectral changes in the FTIR spectra of the PLL film were observed between pH 7 and 8. The decrease in the protonation state of the amino group in the side chain induced spectral changes in the amino group as well as conformational changes in the alkyl group in the side chain. From pH 1-8, the spectral changes in the amino and alkyl groups in the side chain occurred before those of the amide group in the main chain of the surface immobilized PLL film.
2015, 26(2): 177-181
doi: 10.1016/j.cclet.2015.01.013
Abstract:
Two dimensional asynchronous spectra were used to characterize coordination between carbonyl group of butanone and metal ions by using an approach proposed in our recent paper. Spectral variation of n-π* transition band of carbonyl group is used to probe the coordination even if metal ions does not possess any characteristic peak in spectra. Experimental results indicate that Ca2+ and Al3+ show considerable ability to coordinate with the carbonyl group of butanone and bring about spectral variation of the n-π* transition band, which is manifested by cross peaks in 2D asynchronous spectra.
Two dimensional asynchronous spectra were used to characterize coordination between carbonyl group of butanone and metal ions by using an approach proposed in our recent paper. Spectral variation of n-π* transition band of carbonyl group is used to probe the coordination even if metal ions does not possess any characteristic peak in spectra. Experimental results indicate that Ca2+ and Al3+ show considerable ability to coordinate with the carbonyl group of butanone and bring about spectral variation of the n-π* transition band, which is manifested by cross peaks in 2D asynchronous spectra.
2015, 26(2): 182-186
doi: 10.1016/j.cclet.2015.01.014
Abstract:
In this paper, 2D asynchronous spectra generated by using the DAOSD approach was utilized to probe interactions between Nd3+ and pyridinium dissolved in aqueous solution. A series of cross peaks in the resultant 2D asynchronous spectrum confirms the occurrence of intermolecular interaction between Nd3+ and pyridinium. However, no coordination occurs between Nd3+ and pyridinium. Interaction between p electron from aromatic system and f electron from lanthanide ions account for the appearance of cross peaks in2Dasynchronous spectra.Because of the interaction, theemissionspectrumof pyridiniumexhibits a significant change when neodymium perchlorate was introduced into the system.
In this paper, 2D asynchronous spectra generated by using the DAOSD approach was utilized to probe interactions between Nd3+ and pyridinium dissolved in aqueous solution. A series of cross peaks in the resultant 2D asynchronous spectrum confirms the occurrence of intermolecular interaction between Nd3+ and pyridinium. However, no coordination occurs between Nd3+ and pyridinium. Interaction between p electron from aromatic system and f electron from lanthanide ions account for the appearance of cross peaks in2Dasynchronous spectra.Because of the interaction, theemissionspectrumof pyridiniumexhibits a significant change when neodymium perchlorate was introduced into the system.
2015, 26(2): 187-192
doi: 10.1016/j.cclet.2014.11.023
Abstract:
A Keggin-type polyoxomolybdate [H2biim]{Ni(biim)3(SiMo12O40)} [biim=1H,1'H-[2,2']biimidazolyl] has been synthesized under hydrothermal condition and characterized by XRD, temperature-dependent IR, TG, temperature-induced and magnetism-induced 2D infrared correlation spectroscopy (2D-IR COS) and UV-vis DRS in order to explore the relationship between structure and properties. Temperatureinduced 2D-IR COS spectroscopy indicates that the terminal Mo-Ou/v bonds are more sensitive than the bridging Mo=Ot bands to temperature variation, which is in agreement with the conclusion of temperature-dependent IR. Magnetism-dependent 2D-IR COS spectroscopy reveals the stretching vibration of the Mo=Ot occurs prior to the stretching vibration of the Mo-Ou/v, which is due to the coordination environment and the valence of the Siatom. The stability of compound 1 is investigated via TG and temperature-dependent IR. In RhB degradation, compound 1 shows good photocatalytic abilities.
A Keggin-type polyoxomolybdate [H2biim]{Ni(biim)3(SiMo12O40)} [biim=1H,1'H-[2,2']biimidazolyl] has been synthesized under hydrothermal condition and characterized by XRD, temperature-dependent IR, TG, temperature-induced and magnetism-induced 2D infrared correlation spectroscopy (2D-IR COS) and UV-vis DRS in order to explore the relationship between structure and properties. Temperatureinduced 2D-IR COS spectroscopy indicates that the terminal Mo-Ou/v bonds are more sensitive than the bridging Mo=Ot bands to temperature variation, which is in agreement with the conclusion of temperature-dependent IR. Magnetism-dependent 2D-IR COS spectroscopy reveals the stretching vibration of the Mo=Ot occurs prior to the stretching vibration of the Mo-Ou/v, which is due to the coordination environment and the valence of the Siatom. The stability of compound 1 is investigated via TG and temperature-dependent IR. In RhB degradation, compound 1 shows good photocatalytic abilities.
2015, 26(2): 193-196
doi: 10.1016/j.cclet.2014.07.003
Abstract:
The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy technique and two dimensional (2D) correlation analysis. The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal. The appearance of spectral peaks at 1203 cm-1, 1033 cm-1 and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO. According to IR intensity changes after rinsing with deionized water and a NaOH solution, the adsorption was proved to be a chemisorption type. The competition between xanthate and OH- for the surfaces leads to desorption of xanthate at higher pH. The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process, and the results indicated that xanthate micelles were formed at the surfaces. The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at a-PbO was as high as 281 mg g-1 after 150 min.
The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy technique and two dimensional (2D) correlation analysis. The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal. The appearance of spectral peaks at 1203 cm-1, 1033 cm-1 and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO. According to IR intensity changes after rinsing with deionized water and a NaOH solution, the adsorption was proved to be a chemisorption type. The competition between xanthate and OH- for the surfaces leads to desorption of xanthate at higher pH. The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process, and the results indicated that xanthate micelles were formed at the surfaces. The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at a-PbO was as high as 281 mg g-1 after 150 min.
2015, 26(2): 197-199
doi: 10.1016/j.cclet.2015.01.015
Abstract:
Two-dimensional FT-IR correlation spectroscopy was used to reveal the structural changes of isotactic polypropylene (iPP) mesophase during the heating process. The co-relationship among the regular helical bands of iPP was discussed according to synchronous spectrum. The results show that the segments with different length-helixes were found to undergo a disordered process in the temperature range of 25-60℃.
Two-dimensional FT-IR correlation spectroscopy was used to reveal the structural changes of isotactic polypropylene (iPP) mesophase during the heating process. The co-relationship among the regular helical bands of iPP was discussed according to synchronous spectrum. The results show that the segments with different length-helixes were found to undergo a disordered process in the temperature range of 25-60℃.
2015, 26(2): 200-204
doi: 10.1016/j.cclet.2014.12.009
Abstract:
Lanthanum modified materials have been widely used for the removal of hazardous anions. In this study, in situ ATR-FTIR and two-dimensional correlation analysis were employed to investigate the adsorption mechanism of arsenate (As(V)) on lanthanum-impregnated activated alumina (LAA). Our results showed that electrostatic interaction attracted As(V) anions to the LAA surface, and then As(V) could form monodentate configuration on the LAA surface at pH 5-9. The result of 2D-COS showed that two coexistent adsorbed As(V) species, H2AsO4- and HAsO4-2, were adsorbed on the LAA surface without specific sequence at different pH conditions, indicating a negligible role of the incorporated protons of As(V) on the adsorption affinity to LAA surface. The results of this study reveal insights into LAA surface complexes on the molecular scale and provide theoretical support to new metal oxides design for efficient arsenic removal.
Lanthanum modified materials have been widely used for the removal of hazardous anions. In this study, in situ ATR-FTIR and two-dimensional correlation analysis were employed to investigate the adsorption mechanism of arsenate (As(V)) on lanthanum-impregnated activated alumina (LAA). Our results showed that electrostatic interaction attracted As(V) anions to the LAA surface, and then As(V) could form monodentate configuration on the LAA surface at pH 5-9. The result of 2D-COS showed that two coexistent adsorbed As(V) species, H2AsO4- and HAsO4-2, were adsorbed on the LAA surface without specific sequence at different pH conditions, indicating a negligible role of the incorporated protons of As(V) on the adsorption affinity to LAA surface. The results of this study reveal insights into LAA surface complexes on the molecular scale and provide theoretical support to new metal oxides design for efficient arsenic removal.
2015, 26(2): 205-209
doi: 10.1016/j.cclet.2014.10.004
Abstract:
Metal binding of organic ligands can definitely affect its environmental behavior in waters, while information on the binding heterogeneity with different organic ligands is still lacked till now. In this study, the binding of zinc with organic matters associated with cyanobacterial blooms, including dissolved organic matters (DOM) and attached organic matters (AOM), were studied by using fluorescence quenching titration combined with two-dimensional correlation spectroscopy (2D-COS). Metal-induced fluorescent quenching was obviously observed both for DOM and AOM, indicating the formation of metal-ligand complexes. Compared with the one-dimensional spectra, 2D-COS revealed the sequences of metal-ligand interaction with the following orders: 276 nm > 232 nm for DOM and 232 nm > 276 nm for AOM. Furthermore, the modified Stern-Volmer model showed that the binding constant (log KM) of 276 nm in DOM was higher than that of 232 nm (4.93 vs. 4.51), while AOM was characterized with a high binding affinity for 232 nm (log KM: 4.83). The ranks of log KM values were consistent with the sequential orders derived from 2D-COS results both for the two samples. Fluorescence quenching titration combined with 2D-COS was an effective method to characterize the metal-ligand interaction.
Metal binding of organic ligands can definitely affect its environmental behavior in waters, while information on the binding heterogeneity with different organic ligands is still lacked till now. In this study, the binding of zinc with organic matters associated with cyanobacterial blooms, including dissolved organic matters (DOM) and attached organic matters (AOM), were studied by using fluorescence quenching titration combined with two-dimensional correlation spectroscopy (2D-COS). Metal-induced fluorescent quenching was obviously observed both for DOM and AOM, indicating the formation of metal-ligand complexes. Compared with the one-dimensional spectra, 2D-COS revealed the sequences of metal-ligand interaction with the following orders: 276 nm > 232 nm for DOM and 232 nm > 276 nm for AOM. Furthermore, the modified Stern-Volmer model showed that the binding constant (log KM) of 276 nm in DOM was higher than that of 232 nm (4.93 vs. 4.51), while AOM was characterized with a high binding affinity for 232 nm (log KM: 4.83). The ranks of log KM values were consistent with the sequential orders derived from 2D-COS results both for the two samples. Fluorescence quenching titration combined with 2D-COS was an effective method to characterize the metal-ligand interaction.
2015, 26(2): 210-214
doi: 10.1016/j.cclet.2014.11.019
Abstract:
AzoR is a homodimeric, flavin mononucleotide (FMN)-containing, NADH-dependent azoreductase from Escherichia coli. In this paper, we investigated the effect of the concentration of both AzoR and R59G on the spectral behavior of the bound FMN using two-dimensional fluorescence correlation spectra. Two cross peaks (530, 490) and (580, 530) were observed from the dilution-induced 2D asynchronous correlation map of wt AzoR, while only one cross peak appeared at (600, 530) for R59G mutant. This result indicated that the mutation at site 59 influenced the formation of dilution-induced intermediates. The specific activity of both AzoR and R59G mutant was unaffected by dilution when the enzyme concentration is below 1 mmol/L, which suggested that no significant dissociation of FMN occurred at low concentrations. Additionally, in order to explore the origin of these intermediates, we carried out a 2D correlation analysis using excitation wavelength-dependent fluorescence emission spectroscopy. The results showed that there coexisted two types of FMN that emitted fluorescence at 530 nm and 500 nm, respectively. Taken together, these results suggested that the 2D method is a very powerful method to identify the heterogeneous distribution of the bound FMN in solution.
AzoR is a homodimeric, flavin mononucleotide (FMN)-containing, NADH-dependent azoreductase from Escherichia coli. In this paper, we investigated the effect of the concentration of both AzoR and R59G on the spectral behavior of the bound FMN using two-dimensional fluorescence correlation spectra. Two cross peaks (530, 490) and (580, 530) were observed from the dilution-induced 2D asynchronous correlation map of wt AzoR, while only one cross peak appeared at (600, 530) for R59G mutant. This result indicated that the mutation at site 59 influenced the formation of dilution-induced intermediates. The specific activity of both AzoR and R59G mutant was unaffected by dilution when the enzyme concentration is below 1 mmol/L, which suggested that no significant dissociation of FMN occurred at low concentrations. Additionally, in order to explore the origin of these intermediates, we carried out a 2D correlation analysis using excitation wavelength-dependent fluorescence emission spectroscopy. The results showed that there coexisted two types of FMN that emitted fluorescence at 530 nm and 500 nm, respectively. Taken together, these results suggested that the 2D method is a very powerful method to identify the heterogeneous distribution of the bound FMN in solution.
2015, 26(2): 215-220
doi: 10.1016/j.cclet.2015.01.012
Abstract:
In this study, a convenient method using multi-step infrared spectroscopy, including Fourier transform infrared spectroscopy (FT-IR), second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was employed to analyze and discriminate ten marine sponges from two classes collected from the Xisha Islands in the South China Sea. Each sponge had an exclusive macroscopic fingerprint. From the IR spectra, it was noted that the main ingredient of calcareous sponges was calciumcarbonate, but that of demosponges was proteins. For sponges from the same genus or having highly similar chemical profile (IR spectral profile), SD-IR and 2DCOS-IR were applied to successfully reveal the tiny differences. It was demonstrated that the multi-step infrared spectroscopy was a feasible and objective approach for marine sponge identification.
In this study, a convenient method using multi-step infrared spectroscopy, including Fourier transform infrared spectroscopy (FT-IR), second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2DCOS-IR), was employed to analyze and discriminate ten marine sponges from two classes collected from the Xisha Islands in the South China Sea. Each sponge had an exclusive macroscopic fingerprint. From the IR spectra, it was noted that the main ingredient of calcareous sponges was calciumcarbonate, but that of demosponges was proteins. For sponges from the same genus or having highly similar chemical profile (IR spectral profile), SD-IR and 2DCOS-IR were applied to successfully reveal the tiny differences. It was demonstrated that the multi-step infrared spectroscopy was a feasible and objective approach for marine sponge identification.
2015, 26(2): 221-225
doi: 10.1016/j.cclet.2014.11.024
Abstract:
The properties of wood can be improved through steam-heat treatment. There are many studies about mechanical properties of steam-heat treated wood, but very few studies are on the aspects of chemical modifications. In this study, FT-IR spectra combined with SD-IR spectra, correlation coefficients and 2DIR spectra are employed to analyze the chemicalmodifications of teak (Tectona grandis L.F.) wood during steam-heat treatment under treatment temperatures from 120℃ to 220℃ at intervals of 20℃. Acetic acid, which is produced during steam-heat treatment, acts as a catalyst of condensation and degradation reactions of wood components. The changes of wood components are more and more intense with increasing the treatment temperature. The sensitivity of wood samples to thermal perturbation rises initially with increasing treatment temperature before falling back. The steam-heat treated wood under 180℃ is the most sensitive.
The properties of wood can be improved through steam-heat treatment. There are many studies about mechanical properties of steam-heat treated wood, but very few studies are on the aspects of chemical modifications. In this study, FT-IR spectra combined with SD-IR spectra, correlation coefficients and 2DIR spectra are employed to analyze the chemicalmodifications of teak (Tectona grandis L.F.) wood during steam-heat treatment under treatment temperatures from 120℃ to 220℃ at intervals of 20℃. Acetic acid, which is produced during steam-heat treatment, acts as a catalyst of condensation and degradation reactions of wood components. The changes of wood components are more and more intense with increasing the treatment temperature. The sensitivity of wood samples to thermal perturbation rises initially with increasing treatment temperature before falling back. The steam-heat treated wood under 180℃ is the most sensitive.
2015, 26(2): 226-226
Abstract:
2015, 26(2): 227-232
doi: 10.1016/j.cclet.2014.12.014
Abstract:
β,γ-Unsaturated α-diazocarbonyl compounds possess two reactive sites for electrophilic addition -one at the diazo carbon and the other at the vinylogous g-position. Controlled by catalyst, divergent transformations are achieved starting from the same starting materials, either by Lewis acid-catalyzed addition or by dirhodium-catalyzed metal carbene reactions. In select cases two catalysts working in combination or in sequence provide a relay for cascade transformations. In this review, we summarize advances in catalyst-dependent divergent transformations of β,γ-unsaturated α-diazocarbonyl compounds and highlight the potential of this exciting research area and the many challenges that remain.
β,γ-Unsaturated α-diazocarbonyl compounds possess two reactive sites for electrophilic addition -one at the diazo carbon and the other at the vinylogous g-position. Controlled by catalyst, divergent transformations are achieved starting from the same starting materials, either by Lewis acid-catalyzed addition or by dirhodium-catalyzed metal carbene reactions. In select cases two catalysts working in combination or in sequence provide a relay for cascade transformations. In this review, we summarize advances in catalyst-dependent divergent transformations of β,γ-unsaturated α-diazocarbonyl compounds and highlight the potential of this exciting research area and the many challenges that remain.
2015, 26(2): 233-237
doi: 10.1016/j.cclet.2014.10.012
Abstract:
Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCl at elevated temperatures in the presence of superparamagnetic Fe3O4@SiO2 core-shell nanoparticles. Due to the chemical compatibility between SiO2 and MnO2, the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers. The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2 nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles, which are beneficial for applications requiring both high surface area and magnetic separation.
Microflowers made of interconnected MnO2 nanosheets have been successfully synthesized in a microwave reactor through a hydrothermal reduction of KMnO4 with aqueous HCl at elevated temperatures in the presence of superparamagnetic Fe3O4@SiO2 core-shell nanoparticles. Due to the chemical compatibility between SiO2 and MnO2, the heterogeneous reaction leads to the spontaneous encapsulation of the Fe3O4@SiO2 core-shell nanoparticles in the MnO2 microflowers. The resulting hybrid particles exhibit multiple properties including high surface area associated with the MnO2 nanosheets and superparamagnetism originated from the Fe3O4@SiO2 core-shell nanoparticles, which are beneficial for applications requiring both high surface area and magnetic separation.
2015, 26(2): 238-242
doi: 10.1016/j.cclet.2014.11.003
Abstract:
The unusual tricyclo[6.4.0.04,9]dodecane framework was constructed in eight linear steps in 13% overall yield. An innovative strategy accessing the framework from bicyclo[3.3.1]nonanes was employed. The key steps involve a Robinson annulation, a base induced decarboxylation and epimerization in a single step, and an intramolecular alkylation.
The unusual tricyclo[6.4.0.04,9]dodecane framework was constructed in eight linear steps in 13% overall yield. An innovative strategy accessing the framework from bicyclo[3.3.1]nonanes was employed. The key steps involve a Robinson annulation, a base induced decarboxylation and epimerization in a single step, and an intramolecular alkylation.
2015, 26(2): 243-247
doi: 10.1016/j.cclet.2014.11.004
Abstract:
Searching for more safe and effective agents for HIV treatments is still an urgent topic worldwide. Based on our continuous modifications on the benzophenone derivatives as HIV-1 reverse transcriptase (RT) inhibitors, a new template bearing N-phenylbenzenesulfonamide (PBSA) structure was designed to enhance the interactions with HIV-1 RT. In this manuscript, a series of PBSA derivatives were synthesized and evaluated for their anti-HIV-1 activity. The preliminary test showed that these compounds were potent to inhibit wild-type HIV-1 with EC50 values ranging of 0.105-14.531 mmol/L. In particular, compound 13f not only has high anti-HIV-1 activity (0.108 mmol/L), but also possesses low toxicity with a TI value of 1816.6. Furthermore, the major interactions of the inhibitor 13f with HIV-1 RT were also investigated using the molecular modelling. Our discovered structure-activity relationships (SARs) of these analogues may serve as an important clue for further optimizations.
Searching for more safe and effective agents for HIV treatments is still an urgent topic worldwide. Based on our continuous modifications on the benzophenone derivatives as HIV-1 reverse transcriptase (RT) inhibitors, a new template bearing N-phenylbenzenesulfonamide (PBSA) structure was designed to enhance the interactions with HIV-1 RT. In this manuscript, a series of PBSA derivatives were synthesized and evaluated for their anti-HIV-1 activity. The preliminary test showed that these compounds were potent to inhibit wild-type HIV-1 with EC50 values ranging of 0.105-14.531 mmol/L. In particular, compound 13f not only has high anti-HIV-1 activity (0.108 mmol/L), but also possesses low toxicity with a TI value of 1816.6. Furthermore, the major interactions of the inhibitor 13f with HIV-1 RT were also investigated using the molecular modelling. Our discovered structure-activity relationships (SARs) of these analogues may serve as an important clue for further optimizations.
2015, 26(2): 248-250
doi: 10.1016/j.cclet.2014.11.006
Abstract:
Using a catalytic amount of NaI and a stoichiometric oxidant Oxone@, a convenient procedure has been developed for the catalytic oxidative 1,2-shift of arylalkenes in CH3CN/H2O at room temperature, which provides the corresponding a-aryl ketones in moderate to good yields. In this protocol, sodium iodide is first oxidized into hypoiodous acid, which reacts with arylalkene to afford iodohydrin. Then, the iodohydrin is transformed into the a-aryl ketone via an oxidative 1,2-shift rearrangement.
Using a catalytic amount of NaI and a stoichiometric oxidant Oxone@, a convenient procedure has been developed for the catalytic oxidative 1,2-shift of arylalkenes in CH3CN/H2O at room temperature, which provides the corresponding a-aryl ketones in moderate to good yields. In this protocol, sodium iodide is first oxidized into hypoiodous acid, which reacts with arylalkene to afford iodohydrin. Then, the iodohydrin is transformed into the a-aryl ketone via an oxidative 1,2-shift rearrangement.
2015, 26(2): 251-254
doi: 10.1016/j.cclet.2014.11.005
Abstract:
An efficient method for the synthesis of benzo[b]benzofurano[2,3-e][1,6]naphthyridine-8-one derivatives has been developed via Pictet-Spengler reaction of 4-(3-aminobenzofuran-2-yl)quinoline- 2-ones, which could be obtained from alkylation of 4-bromomethylquinoline-2-ones with salicylonitrile and subsequent Thorpe-Ziegler isomerization, with aromatic aldehydes under p-TsOH as catalyst in good yields.
An efficient method for the synthesis of benzo[b]benzofurano[2,3-e][1,6]naphthyridine-8-one derivatives has been developed via Pictet-Spengler reaction of 4-(3-aminobenzofuran-2-yl)quinoline- 2-ones, which could be obtained from alkylation of 4-bromomethylquinoline-2-ones with salicylonitrile and subsequent Thorpe-Ziegler isomerization, with aromatic aldehydes under p-TsOH as catalyst in good yields.
2015, 26(2): 255-258
doi: 10.1016/j.cclet.2014.11.021
Abstract:
Acid hydrolysis mechanisms of orientin-2″-O-galactopyranoside (OGA), orientin and other flavone C-glycosides in the trollflowers (Trollius chinensis Bunge) were studied in this report for the first time. Hydrolysis parameters including temperature, acidity, solvent and reaction time were comprehensively investigated. OGA could be hydrolyzed to orientin, followed by an isomerization to isoorientin to isoorientin via a reversible Wessely-Moser rearrangement reaction under stronger acidic conditions. A first-order kinetic model fitted the hydrolysis process of OGA well. Under the optimal hydrolysis conditions of 80℃, 1.0 mol/L H+ and 7 h reaction time, about 77% OGA was transformed to orientin with no detectable isoorientin. These results could be helpful for better understanding of the acid hydrolysis kinetics of flavone C-glycosides, as well as the preparation of these valuable components under controlled acid hydrolysis conditions.
Acid hydrolysis mechanisms of orientin-2″-O-galactopyranoside (OGA), orientin and other flavone C-glycosides in the trollflowers (Trollius chinensis Bunge) were studied in this report for the first time. Hydrolysis parameters including temperature, acidity, solvent and reaction time were comprehensively investigated. OGA could be hydrolyzed to orientin, followed by an isomerization to isoorientin to isoorientin via a reversible Wessely-Moser rearrangement reaction under stronger acidic conditions. A first-order kinetic model fitted the hydrolysis process of OGA well. Under the optimal hydrolysis conditions of 80℃, 1.0 mol/L H+ and 7 h reaction time, about 77% OGA was transformed to orientin with no detectable isoorientin. These results could be helpful for better understanding of the acid hydrolysis kinetics of flavone C-glycosides, as well as the preparation of these valuable components under controlled acid hydrolysis conditions.
2015, 26(2): 259-262
doi: 10.1016/j.cclet.2014.11.002
Abstract:
Under the guidance of the finding that the tyrosine residues in proteins could undergo three-component Mannich-type reactions with formaldehyde and electron-rich aniline-containing compounds, which forms covalent bonding connections between the protein of interest and the aniline with high levels of selectivity under relatively mild conditions, an orange aromatic primary amine-containing acid dye AMODB was designed and readily synthesized. The molecular structure was characterized by FTIR, 1H NMR, mass spectrometry and elemental analysis. The synthesized dye and a similar control dye (C.I. Acid Yellow 11) without primary amine groups were applied to dye silk fabric by three dyeing processes: Mannich-type dyeing (with and without the addition of formaldehyde) and acidic dyeing. Their washing and rubbing fastness properties with different dyeing methods were examined and compared. It was found that the dyed silk fabric with AMODB by the Mannich-type dyeing showed higher color depth, better anti-stripping ability to DMF and better washing fastness than those of the dyed silk fabric with C.I. Acid Yellow 11 by acidic dyeing due to the covalent bond formation between the dye chromophore of AMODB and silk fiber. In addition, mild Mannich dyeing conditions suitable for silk (AMODB at 3% owf, 75:1 liquor-to-goods ratio, dyebath pH 5.5, 30 8C, 10 h) were provided.
Under the guidance of the finding that the tyrosine residues in proteins could undergo three-component Mannich-type reactions with formaldehyde and electron-rich aniline-containing compounds, which forms covalent bonding connections between the protein of interest and the aniline with high levels of selectivity under relatively mild conditions, an orange aromatic primary amine-containing acid dye AMODB was designed and readily synthesized. The molecular structure was characterized by FTIR, 1H NMR, mass spectrometry and elemental analysis. The synthesized dye and a similar control dye (C.I. Acid Yellow 11) without primary amine groups were applied to dye silk fabric by three dyeing processes: Mannich-type dyeing (with and without the addition of formaldehyde) and acidic dyeing. Their washing and rubbing fastness properties with different dyeing methods were examined and compared. It was found that the dyed silk fabric with AMODB by the Mannich-type dyeing showed higher color depth, better anti-stripping ability to DMF and better washing fastness than those of the dyed silk fabric with C.I. Acid Yellow 11 by acidic dyeing due to the covalent bond formation between the dye chromophore of AMODB and silk fiber. In addition, mild Mannich dyeing conditions suitable for silk (AMODB at 3% owf, 75:1 liquor-to-goods ratio, dyebath pH 5.5, 30 8C, 10 h) were provided.
2015, 26(2): 263-266
doi: 10.1016/j.cclet.2014.11.007
Abstract:
In this communication, we report four component condensations of acetophenone, arylaldehydes, arylthiol, and malononitrile in the presence of Triton X-100 (5 mol%) aqueous micelles. This reaction led to the formation of 4,6-diaryl-2-(arylthio)nicotinonitrile new derivatives in good yields. The FT-IR, 19F NMR, 1H NMR, 13C NMR spectra and elemental analysis confirm the structure of compounds.
In this communication, we report four component condensations of acetophenone, arylaldehydes, arylthiol, and malononitrile in the presence of Triton X-100 (5 mol%) aqueous micelles. This reaction led to the formation of 4,6-diaryl-2-(arylthio)nicotinonitrile new derivatives in good yields. The FT-IR, 19F NMR, 1H NMR, 13C NMR spectra and elemental analysis confirm the structure of compounds.
