ABSTRACT The 5-parameter Morse potential (5-MP) of the interaction between oxygen atoms and iron ... more ABSTRACT The 5-parameter Morse potential (5-MP) of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe(211) high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe(100) surface with an eigenvibration at 437 cm−1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O—Fe(110) system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe(111) and Fe(211) surfaces, O atoms predominantly occupy the quasi-3-fold site.
A reversible fluorescence nanoswitch by integrating carbon quantum dots nanoassembly and pyrophos... more A reversible fluorescence nanoswitch by integrating carbon quantum dots nanoassembly and pyrophosphate ion is developed, and a reliable real-time fluorescent assay for acid phosphatase (ACP) activity is established on the basis of the fluorescence nanoswitch. Carbon quantum dots (CQDs) abundant in carboxyl groups on the surface, nickel(II) ion and pyrophosphate ion comprise the fluorescent nanoswitch, which operates in the following way: the nanoassembly consisting of CQDs and nickel ions can be triggered by pyrophosphate ion serving as an external stimulus. At the same time, the fluorescence nanoswitch switches between two fluorescence states (OFF and ON) accompanying shifts in their physical states aggregation and disaggregation. Based on the nanoswitch, the introduction of ACP leads to breakdown of pyrophosphate ions into phosphate ions and resultant fluorescence quenching due to catalytic hydrolysis of ACP toward pyrophosphate ions (PPi). Quantitative evaluation of ACP activity in a broad range from 18.2 U/L to 1300 U/L, with a detection limit of 5.5 U/L, can be achieved in this way, which endows the assay with sufficiently high sensitivity for practical detection in human serum and seminal plasma.
ABSTRACT Dominant components of oxidized products of multi-walled carbon nanotubes were separated... more ABSTRACT Dominant components of oxidized products of multi-walled carbon nanotubes were separated by column chromatography, the origin of highly visible fluorescence from carbon quantum dots was revealed, and the nature of weak near-UV-Vis fluorescence of oxidized carbon nanotubes from isolated sp2 carbon clusters was supported among the four proposed explanations through experimental and theoretical approaches. It was found that three dominant components including carbon quantum dots, short and long oxidized carbon nanotubes were produced during the oxidation of carbon nanotubes. The highly visible fluorescence was mainly originated from carbon quantum dots, while short and long oxidized carbon nanotubes only exhibited weak near-UV-Vis fluorescence. For the nature of fluorescence of oxidized carbon nanotubes, two proposed explanations including defects mechanism and an isolated carbon cluster mechanism were compared and discussed through theoretical analysis of corresponding model compounds. It was supported that the fluorescence is dominantly originated from sp2 carbon clusters isolated by sp3 carbons due to oxidation depending on the comparison between experimental data and calculated values. The results also indicated that carbon nanotubes can be transformed to large graphene oxide during oxidation. This work not only clearly demonstrated the origin of highly visible fluorescence in an oxidized carbon nanotube mixture and a reasonable explanation for fluorescence of oxidized carbon nanotubes, but also provided an example to understand visible fluorescent graphene oxide and carbon quantum dots.
ABSTRACT P-doped C quantum dots (PCQDs) are prepared by solvothermal reaction of PBr3 and hydroqu... more ABSTRACT P-doped C quantum dots (PCQDs) are prepared by solvothermal reaction of PBr3 and hydroquinone in the presence of NaOH in Me2CO (autoclave, 200 °C, 1 h).
Chemistry (Weinheim an der Bergstrasse, Germany), 2014
Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene qua... more Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene quantum dots (GQDs) and carbon nanotubes (CNTs) platform through spontaneous assembly between dual-color GQD-based probes and CNTs and subsequently self-recognition between DNA probes and targets.
A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activ... more A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activity in the continuous and recyclable way is established on the basis of aggregation and disaggregation of carbon quantum dots (CQDs) through the competitive assay approach. CQDs and adenosine triphosphate (ATP) were used as the fluorescent indicator and substrate for ALP activity assessment, respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by cerium ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, ATP can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to cerium ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by redispersion of CQDs in the presence of ALP and ATP. Quantitative evaluation of ALP activity in a broad range from 4.6 to 383.3 U/L with the detection limit of 1.4 U/L can be realized in this way, which en...
Convenient and simultaneous detection of multiple biomarkers such as DNA and proteins with biocom... more Convenient and simultaneous detection of multiple biomarkers such as DNA and proteins with biocompatible materials and good analytical performance still remains a challenge. Herein, we report the respective and simultaneous detection of DNA and bovine α-thrombin (thrombin) entirely based on biocompatible carbon materials through a specially designed fluorescence on-off-on process. Colorful fluorescence, high emission efficiency, good photostability and excellent compatibility enables graphene quantum dots (GQDs) as the best choice for fluorophores in bioprobes, and thus two-colored GQDs as labeling fluorophores were chemically bonded with specific oligonucleotide sequence and aptamer to prepare two probes targeting the DNA and thrombin, respectively. Each probe can be assembled on the graphene oxide (GO) platform spontaneously by π-π stacking and electrostatic attraction; as a result, fast electron transfer in the assembly efficiently quenches the fluorescence of probe. The presence...
The sensitive detection of heavy metal ions in the organism and aquatic ecosystem using nanosenso... more The sensitive detection of heavy metal ions in the organism and aquatic ecosystem using nanosensors based on environment friendly and biocompatible materials still remains a challenge. A fluorescent turn-on nanosensor for lead (II) detection based on biocompatible graphene quantum dots and graphene oxide by employment of Pb(2+)-induced G-quadruplex formation was reported. Graphene quantum dots with high quantum yield, good biocompatibility were prepared and served as the fluorophore of Pb(2+) probe. Fluorescence turn-off of graphene quantum dots is easily achieved through efficient photoinduced electron transfer between graphene quantum dots and graphene oxide, and subsequent fluorescence turn-on process is due to the formation of G-quadraplex aptamer-Pb(2+) complex triggered by the addition of Pb(2+). This nanosensor can distinguish Pb(2+) ion from other ions with high sensitivity and good reproducibility. The detection method based on this nanosensor possesses a fast response time...
A convenient and real-time fluorometric assay with the assistance of copper ions based on aggrega... more A convenient and real-time fluorometric assay with the assistance of copper ions based on aggregation and disaggregation of carbon quantum dots (CQDs) was developed to achieve highly sensitive detection of alkaline phosphatase activity. CQDs and pyrophosphate anions (PPi) were used as the fluorescent indicator and substrate for ALP activity assessment respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by copper ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, PPi can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to copper ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by re-dispersion of CQDs in the presence of ALP and PPi. Quantitative evaluation of ALP activity in a broad range from 16.7 to 782.6U/L with the detection limit of 1.1U/L can be realized in this way, which endows the assay with high enough sens...
Assessment of the accuracy of methods including 29 DFT methods and 2 ab initio wave function theo... more Assessment of the accuracy of methods including 29 DFT methods and 2 ab initio wave function theory (WFT) methods for predicting (27)Al nuclear magnetic resonance shielding tensors of aquated Al(III) species was carried out. Among all of the tested methods, HF and MP2 methods give the best performance for the calculations of chemical shifts. Among all of the DFT methods with GIAO calculations, O3LYP and MPWKCIS1K are the most accurate models for calculations of chemical shifts, followed in order by BHandHLYP, B98, B97-1, mPW1PW91, PBE1PBE, and MPW1KCIS. Among all of the DFT methods with CSGT calculations, VSXC is the best method for the prediction of chemical shifts, followed in order by TPSSh, B97-2, O3LYP, TPSS, TPSS1KCIS, MPWKCIS1K, BHandHLYP, B97-1, and B98. The popular B3LYP method overestimates largely the chemical shifts with both GIAO and CSGT methods. The calculated results indicate that the predictions of (27)Al chemical shifts on the base of the model that includes both explicit solvent effect and bulk solvent effect are most accurate for aquated Al(III) species.
Fluorescent B-doped carbon quantum dots (BCQDs) were prepared by a facile one-pot solvothermal ro... more Fluorescent B-doped carbon quantum dots (BCQDs) were prepared by a facile one-pot solvothermal route. The BCQDs can be used as a novel fluorescence sensing system for hydrogen peroxide and glucose detection.
The formation mechanism of bipyridyl molecule catalyzed by nickel catalyst with pyridine precurso... more The formation mechanism of bipyridyl molecule catalyzed by nickel catalyst with pyridine precursor has been studied using density functional theory calculations. The formation of bipyridyl on Ni(111) surface from two pyridine molecules is considered as the initial process of N-doped graphene growth, and the minimum energy pathway for the formation has been investigated in detail. The whole formation processes mainly includes three steps, i.e., the dehydrogenation of the first pyridine, adsorption and dehydrogenation of the second pyridine, and formation of the bipyridyl molecule. It is found that the C-H bond of pyridine could be selectively dissociated while the C-C and C-N bond connections are retained during the catalytic processes. The N-doped graphene formed by pyridine only contains pyridine-like nitrogen atoms, suggesting a possible way to produce N-doped graphene with pure pyridine-like nitrogen atoms. The comparison of formation mechanisms between bipyridyl and biphenyl molecules was carried out, and the results imply a lower temperature process for synthesis of N-doped graphene from pyridine than that for graphene from benzene.
Supermolecule density functional calculations were performed on the hydrolysis of aluminum(III) a... more Supermolecule density functional calculations were performed on the hydrolysis of aluminum(III) and prediction of pK(a) in aqueous solution. The optimization results showed that the most stable structures for the first, second and third hydrolysis products were hexacoordinate, hexacoordinate and pentacoordinate, respectively. The different coordination geometries could easily transform into each other due to the small energy gaps (within 2.5 kcal mol(-1)). The calculated value of 4.6 for the first hydrolysis constant agreed well with the experimental value of 5.0. The results from the different thermodynamic cycles have been compared, which revealed that the cycle involving the solvation of H(2)O and H(3)O(+) could reasonably predict the first hydrolysis constant, while the other cycle involving the solvation of H(+) acquired a fairly good correlation of the hydrolysis reaction free energies and the experimental pK(a).
A Cu-catalyzed divergent hydroboration of thioacetylenes has been achieved, providing (Z)-1-thio-... more A Cu-catalyzed divergent hydroboration of thioacetylenes has been achieved, providing (Z)-1-thio- or (Z)-2-thio-1-alkenyl boronates in moderate to high yields with excellent regio- and stereoselectivity, by using pinacolborane or bis(pinacolato)diboron as the hydroborating reagents, respectively. DFT calculations indicate that the sulfur atom plays a key role in determining the regioselectivity through polarizing the C-C triple bonds and participating in the HOMO orbitals. Moreover, the SR group can serve as a good leaving group, resulting in the concise synthesis of six regio- and stereoisomers of trisubstituted alkenes 5 via the iterative cross-coupling of C-B and C-S bonds. Clearly, it will be valuable for assembling stereochemically diverse trisubstituted olefins in organic synthesis.
ABSTRACT Nanosized N-doped graphene oxide (GO) with visible fluorescence in water was prepared by... more ABSTRACT Nanosized N-doped graphene oxide (GO) with visible fluorescence in water was prepared by cutting and unzipping of N-doped carbon nanotubes (NCNTs) and used to distinguish between normal and transition metal ions. It is found that the fluorescence is bathochromically shifted as the level of oxidation is increased.
ABSTRACT The 5-parameter Morse potential (5-MP) of the interaction between oxygen atoms and iron ... more ABSTRACT The 5-parameter Morse potential (5-MP) of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe(211) high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe(100) surface with an eigenvibration at 437 cm−1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O—Fe(110) system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe(111) and Fe(211) surfaces, O atoms predominantly occupy the quasi-3-fold site.
A reversible fluorescence nanoswitch by integrating carbon quantum dots nanoassembly and pyrophos... more A reversible fluorescence nanoswitch by integrating carbon quantum dots nanoassembly and pyrophosphate ion is developed, and a reliable real-time fluorescent assay for acid phosphatase (ACP) activity is established on the basis of the fluorescence nanoswitch. Carbon quantum dots (CQDs) abundant in carboxyl groups on the surface, nickel(II) ion and pyrophosphate ion comprise the fluorescent nanoswitch, which operates in the following way: the nanoassembly consisting of CQDs and nickel ions can be triggered by pyrophosphate ion serving as an external stimulus. At the same time, the fluorescence nanoswitch switches between two fluorescence states (OFF and ON) accompanying shifts in their physical states aggregation and disaggregation. Based on the nanoswitch, the introduction of ACP leads to breakdown of pyrophosphate ions into phosphate ions and resultant fluorescence quenching due to catalytic hydrolysis of ACP toward pyrophosphate ions (PPi). Quantitative evaluation of ACP activity in a broad range from 18.2 U/L to 1300 U/L, with a detection limit of 5.5 U/L, can be achieved in this way, which endows the assay with sufficiently high sensitivity for practical detection in human serum and seminal plasma.
ABSTRACT Dominant components of oxidized products of multi-walled carbon nanotubes were separated... more ABSTRACT Dominant components of oxidized products of multi-walled carbon nanotubes were separated by column chromatography, the origin of highly visible fluorescence from carbon quantum dots was revealed, and the nature of weak near-UV-Vis fluorescence of oxidized carbon nanotubes from isolated sp2 carbon clusters was supported among the four proposed explanations through experimental and theoretical approaches. It was found that three dominant components including carbon quantum dots, short and long oxidized carbon nanotubes were produced during the oxidation of carbon nanotubes. The highly visible fluorescence was mainly originated from carbon quantum dots, while short and long oxidized carbon nanotubes only exhibited weak near-UV-Vis fluorescence. For the nature of fluorescence of oxidized carbon nanotubes, two proposed explanations including defects mechanism and an isolated carbon cluster mechanism were compared and discussed through theoretical analysis of corresponding model compounds. It was supported that the fluorescence is dominantly originated from sp2 carbon clusters isolated by sp3 carbons due to oxidation depending on the comparison between experimental data and calculated values. The results also indicated that carbon nanotubes can be transformed to large graphene oxide during oxidation. This work not only clearly demonstrated the origin of highly visible fluorescence in an oxidized carbon nanotube mixture and a reasonable explanation for fluorescence of oxidized carbon nanotubes, but also provided an example to understand visible fluorescent graphene oxide and carbon quantum dots.
ABSTRACT P-doped C quantum dots (PCQDs) are prepared by solvothermal reaction of PBr3 and hydroqu... more ABSTRACT P-doped C quantum dots (PCQDs) are prepared by solvothermal reaction of PBr3 and hydroquinone in the presence of NaOH in Me2CO (autoclave, 200 °C, 1 h).
Chemistry (Weinheim an der Bergstrasse, Germany), 2014
Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene qua... more Simultaneous detection of multiple DNA targets was achieved based on a biocompatible graphene quantum dots (GQDs) and carbon nanotubes (CNTs) platform through spontaneous assembly between dual-color GQD-based probes and CNTs and subsequently self-recognition between DNA probes and targets.
A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activ... more A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activity in the continuous and recyclable way is established on the basis of aggregation and disaggregation of carbon quantum dots (CQDs) through the competitive assay approach. CQDs and adenosine triphosphate (ATP) were used as the fluorescent indicator and substrate for ALP activity assessment, respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by cerium ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, ATP can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to cerium ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by redispersion of CQDs in the presence of ALP and ATP. Quantitative evaluation of ALP activity in a broad range from 4.6 to 383.3 U/L with the detection limit of 1.4 U/L can be realized in this way, which en...
Convenient and simultaneous detection of multiple biomarkers such as DNA and proteins with biocom... more Convenient and simultaneous detection of multiple biomarkers such as DNA and proteins with biocompatible materials and good analytical performance still remains a challenge. Herein, we report the respective and simultaneous detection of DNA and bovine α-thrombin (thrombin) entirely based on biocompatible carbon materials through a specially designed fluorescence on-off-on process. Colorful fluorescence, high emission efficiency, good photostability and excellent compatibility enables graphene quantum dots (GQDs) as the best choice for fluorophores in bioprobes, and thus two-colored GQDs as labeling fluorophores were chemically bonded with specific oligonucleotide sequence and aptamer to prepare two probes targeting the DNA and thrombin, respectively. Each probe can be assembled on the graphene oxide (GO) platform spontaneously by π-π stacking and electrostatic attraction; as a result, fast electron transfer in the assembly efficiently quenches the fluorescence of probe. The presence...
The sensitive detection of heavy metal ions in the organism and aquatic ecosystem using nanosenso... more The sensitive detection of heavy metal ions in the organism and aquatic ecosystem using nanosensors based on environment friendly and biocompatible materials still remains a challenge. A fluorescent turn-on nanosensor for lead (II) detection based on biocompatible graphene quantum dots and graphene oxide by employment of Pb(2+)-induced G-quadruplex formation was reported. Graphene quantum dots with high quantum yield, good biocompatibility were prepared and served as the fluorophore of Pb(2+) probe. Fluorescence turn-off of graphene quantum dots is easily achieved through efficient photoinduced electron transfer between graphene quantum dots and graphene oxide, and subsequent fluorescence turn-on process is due to the formation of G-quadraplex aptamer-Pb(2+) complex triggered by the addition of Pb(2+). This nanosensor can distinguish Pb(2+) ion from other ions with high sensitivity and good reproducibility. The detection method based on this nanosensor possesses a fast response time...
A convenient and real-time fluorometric assay with the assistance of copper ions based on aggrega... more A convenient and real-time fluorometric assay with the assistance of copper ions based on aggregation and disaggregation of carbon quantum dots (CQDs) was developed to achieve highly sensitive detection of alkaline phosphatase activity. CQDs and pyrophosphate anions (PPi) were used as the fluorescent indicator and substrate for ALP activity assessment respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by copper ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, PPi can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to copper ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by re-dispersion of CQDs in the presence of ALP and PPi. Quantitative evaluation of ALP activity in a broad range from 16.7 to 782.6U/L with the detection limit of 1.1U/L can be realized in this way, which endows the assay with high enough sens...
Assessment of the accuracy of methods including 29 DFT methods and 2 ab initio wave function theo... more Assessment of the accuracy of methods including 29 DFT methods and 2 ab initio wave function theory (WFT) methods for predicting (27)Al nuclear magnetic resonance shielding tensors of aquated Al(III) species was carried out. Among all of the tested methods, HF and MP2 methods give the best performance for the calculations of chemical shifts. Among all of the DFT methods with GIAO calculations, O3LYP and MPWKCIS1K are the most accurate models for calculations of chemical shifts, followed in order by BHandHLYP, B98, B97-1, mPW1PW91, PBE1PBE, and MPW1KCIS. Among all of the DFT methods with CSGT calculations, VSXC is the best method for the prediction of chemical shifts, followed in order by TPSSh, B97-2, O3LYP, TPSS, TPSS1KCIS, MPWKCIS1K, BHandHLYP, B97-1, and B98. The popular B3LYP method overestimates largely the chemical shifts with both GIAO and CSGT methods. The calculated results indicate that the predictions of (27)Al chemical shifts on the base of the model that includes both explicit solvent effect and bulk solvent effect are most accurate for aquated Al(III) species.
Fluorescent B-doped carbon quantum dots (BCQDs) were prepared by a facile one-pot solvothermal ro... more Fluorescent B-doped carbon quantum dots (BCQDs) were prepared by a facile one-pot solvothermal route. The BCQDs can be used as a novel fluorescence sensing system for hydrogen peroxide and glucose detection.
The formation mechanism of bipyridyl molecule catalyzed by nickel catalyst with pyridine precurso... more The formation mechanism of bipyridyl molecule catalyzed by nickel catalyst with pyridine precursor has been studied using density functional theory calculations. The formation of bipyridyl on Ni(111) surface from two pyridine molecules is considered as the initial process of N-doped graphene growth, and the minimum energy pathway for the formation has been investigated in detail. The whole formation processes mainly includes three steps, i.e., the dehydrogenation of the first pyridine, adsorption and dehydrogenation of the second pyridine, and formation of the bipyridyl molecule. It is found that the C-H bond of pyridine could be selectively dissociated while the C-C and C-N bond connections are retained during the catalytic processes. The N-doped graphene formed by pyridine only contains pyridine-like nitrogen atoms, suggesting a possible way to produce N-doped graphene with pure pyridine-like nitrogen atoms. The comparison of formation mechanisms between bipyridyl and biphenyl molecules was carried out, and the results imply a lower temperature process for synthesis of N-doped graphene from pyridine than that for graphene from benzene.
Supermolecule density functional calculations were performed on the hydrolysis of aluminum(III) a... more Supermolecule density functional calculations were performed on the hydrolysis of aluminum(III) and prediction of pK(a) in aqueous solution. The optimization results showed that the most stable structures for the first, second and third hydrolysis products were hexacoordinate, hexacoordinate and pentacoordinate, respectively. The different coordination geometries could easily transform into each other due to the small energy gaps (within 2.5 kcal mol(-1)). The calculated value of 4.6 for the first hydrolysis constant agreed well with the experimental value of 5.0. The results from the different thermodynamic cycles have been compared, which revealed that the cycle involving the solvation of H(2)O and H(3)O(+) could reasonably predict the first hydrolysis constant, while the other cycle involving the solvation of H(+) acquired a fairly good correlation of the hydrolysis reaction free energies and the experimental pK(a).
A Cu-catalyzed divergent hydroboration of thioacetylenes has been achieved, providing (Z)-1-thio-... more A Cu-catalyzed divergent hydroboration of thioacetylenes has been achieved, providing (Z)-1-thio- or (Z)-2-thio-1-alkenyl boronates in moderate to high yields with excellent regio- and stereoselectivity, by using pinacolborane or bis(pinacolato)diboron as the hydroborating reagents, respectively. DFT calculations indicate that the sulfur atom plays a key role in determining the regioselectivity through polarizing the C-C triple bonds and participating in the HOMO orbitals. Moreover, the SR group can serve as a good leaving group, resulting in the concise synthesis of six regio- and stereoisomers of trisubstituted alkenes 5 via the iterative cross-coupling of C-B and C-S bonds. Clearly, it will be valuable for assembling stereochemically diverse trisubstituted olefins in organic synthesis.
ABSTRACT Nanosized N-doped graphene oxide (GO) with visible fluorescence in water was prepared by... more ABSTRACT Nanosized N-doped graphene oxide (GO) with visible fluorescence in water was prepared by cutting and unzipping of N-doped carbon nanotubes (NCNTs) and used to distinguish between normal and transition metal ions. It is found that the fluorescence is bathochromically shifted as the level of oxidation is increased.
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