Scott E. Boesch, Shawna S. York, R. Frech, R. Wheeler
A combination of hybrid Hartree?Fock/density functional calculations and Raman and IR spectroscopy has been used to perform a vibrational analysis of N,N'-dimethylethylenediamine (DMEDA) and provide band assignments for the experimental spectroscopic data. The structures and vibrational frequencies of several low energy conformations of DMEDA were calculated. The lowest energy structure was found to be TGT with a single intramolecular hydrogen bond. The effect of intramolecular hydrogen bonding on the structures and vibrational frequencies was investigated. Liquid DMEDA is found to be predominantly a mixture of two conformations: TGT with one intramolecular hydrogen bond and TGT with no intramolecular hydrogen bonds
{"title":"An experimental and computational investigation of the structure and vibrations of dimethylethylenediamine, a model for poly(ethylenimine)","authors":"Scott E. Boesch, Shawna S. York, R. Frech, R. Wheeler","doi":"10.1039/B009250I","DOIUrl":"https://doi.org/10.1039/B009250I","url":null,"abstract":"A combination of hybrid Hartree?Fock/density functional calculations and Raman and IR spectroscopy has been used to perform a vibrational analysis of N,N'-dimethylethylenediamine (DMEDA) and provide band assignments for the experimental spectroscopic data. The structures and vibrational frequencies of several low energy conformations of DMEDA were calculated. The lowest energy structure was found to be TGT with a single intramolecular hydrogen bond. The effect of intramolecular hydrogen bonding on the structures and vibrational frequencies was investigated. Liquid DMEDA is found to be predominantly a mixture of two conformations: TGT with one intramolecular hydrogen bond and TGT with no intramolecular hydrogen bonds","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"26 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88000610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
X-ray diffraction patterns of hydrated Na-X zeolite at 1 atm and 22 °C, recovered from high pressure experiments at pressures up to 9 GPa, showed progressive amorphization with increasing pressure. The largest reduction in crystallinity is observed between pressures of 4 and 5 GPa followed by a gradual, continued decrease in ordering up to the maximum pressure. The last vestiges of crystal structure persist to 8 GPa but the sample is completely amorphous at 9 GPa. Heating to 873 K in a differential scanning calorimetry (DSC) apparatus after decompression showed a shift in the broad dehydration endotherm to lower temperatures and a decrease in the endotherm width with increasing pressure. Follow-up X-ray patterns at 1 atm and 295 K after heating showed significant changes in peak intensities and width of the amorphous background signature. These observations are consistent with the negative thermal expansion of Na-X zeolite which results in further compression of the remnant lattice on heating.
{"title":"Pressure-induced amorphization of hydrated Na-X zeolite","authors":"Hongjiang Liu, R. Secco, Yining Huang","doi":"10.1039/B102080N","DOIUrl":"https://doi.org/10.1039/B102080N","url":null,"abstract":"X-ray diffraction patterns of hydrated Na-X zeolite at 1 atm and 22 °C, recovered from high pressure experiments at pressures up to 9 GPa, showed progressive amorphization with increasing pressure. The largest reduction in crystallinity is observed between pressures of 4 and 5 GPa followed by a gradual, continued decrease in ordering up to the maximum pressure. The last vestiges of crystal structure persist to 8 GPa but the sample is completely amorphous at 9 GPa. Heating to 873 K in a differential scanning calorimetry (DSC) apparatus after decompression showed a shift in the broad dehydration endotherm to lower temperatures and a decrease in the endotherm width with increasing pressure. Follow-up X-ray patterns at 1 atm and 295 K after heating showed significant changes in peak intensities and width of the amorphous background signature. These observations are consistent with the negative thermal expansion of Na-X zeolite which results in further compression of the remnant lattice on heating.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"45 1","pages":"37-39"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86580511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Gole, Arun Kumar, S. Phadtare, A. B. Mandale, M. Sastry
The formation of gold nanoparticle–lipid composite films by glucose-induced reduction of chloroaurate ions entrapped in thermally evaporated fatty amine films is described. Simple immersion of films of the salt of octadecylamine and chloroaurate ions (formed by immersion of thermally evaporated fatty amine films in chloroauric acid solution) in glucose solution leads to the facile in-situ reduction of the metal ions to form gold nanoparticles in the fatty amine matrix. The formation of gold nanoparticles is readily detected by the appearance of a violet color in the film and thus forms the basis of a possible new, gold nanoparticle-based colorimetric sensor for glucose. The formation of the fatty amine salt of chloroauric acid and the subsequent reduction of the metal ions by glucose has been followed by quartz crystal microgravimetry, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy and transmission electron microscopy measurements.
{"title":"Glucose induced in-situ reduction of chloroaurate ions entrapped in a fatty amine film: formation of gold nanoparticle–lipid composites","authors":"A. Gole, Arun Kumar, S. Phadtare, A. B. Mandale, M. Sastry","doi":"10.1039/B106564E","DOIUrl":"https://doi.org/10.1039/B106564E","url":null,"abstract":"The formation of gold nanoparticle–lipid composite films by glucose-induced reduction of chloroaurate ions entrapped in thermally evaporated fatty amine films is described. Simple immersion of films of the salt of octadecylamine and chloroaurate ions (formed by immersion of thermally evaporated fatty amine films in chloroauric acid solution) in glucose solution leads to the facile in-situ reduction of the metal ions to form gold nanoparticles in the fatty amine matrix. The formation of gold nanoparticles is readily detected by the appearance of a violet color in the film and thus forms the basis of a possible new, gold nanoparticle-based colorimetric sensor for glucose. The formation of the fatty amine salt of chloroauric acid and the subsequent reduction of the metal ions by glucose has been followed by quartz crystal microgravimetry, Fourier transform infrared spectroscopy, X-ray photoemission spectroscopy and transmission electron microscopy measurements.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"9 1","pages":"92-95"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79516223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The thermodynamics of dilute solution of Gd in Bi were determined by means of the electromotive force (EMF) measurement method using a cell consisting of molten chloride and liquid bismuth in temperature range from 775 to 1055 K, with the Gd molar fraction range from about 10 –5 to 10 –3 . Gd concentration has less effect on the activity coefficient. A considerable increase of the activity coefficient on the temperature was observed. The heat of formation of liquid Gd–Bi alloys was deduced from the measured activity coefficient. There is a linear dependence of experimental ΔHMGd–Bi on the Gd concentration. The experimental results of ΔHMGd–Bi were compared with the values predicted by Miedema's model.
{"title":"Thermodynamics of dilute solution of Gd in Bi","authors":"J. Sheng, H. Yamana, H. Moriyama","doi":"10.1039/B101001H","DOIUrl":"https://doi.org/10.1039/B101001H","url":null,"abstract":"The thermodynamics of dilute solution of Gd in Bi were determined by means of the electromotive force (EMF) measurement method using a cell consisting of molten chloride and liquid bismuth in temperature range from 775 to 1055 K, with the Gd molar fraction range from about 10 –5 to 10 –3 . Gd concentration has less effect on the activity coefficient. A considerable increase of the activity coefficient on the temperature was observed. The heat of formation of liquid Gd–Bi alloys was deduced from the measured activity coefficient. There is a linear dependence of experimental ΔHMGd–Bi on the Gd concentration. The experimental results of ΔHMGd–Bi were compared with the values predicted by Miedema's model.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"22 1","pages":"40-43"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78483833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel ZnO (zinc oxide)–PANI (polyaniline) composite film on PATP (ρ-aminothiophenol)/Au was prepared by electrochemical-assembly (ECA) and sol–gel technique, and this composite film shows excellent luminescent performance and high photoelectrochemical conversion efficiency, which can be industrially used for luminescent nanomaterials and treating wastewater containing methyl orange.
{"title":"The preparation and characterization of ZnO–PANI (polyaniline) composite film on PATP (ρ-aminothiophenol)/Au","authors":"Z. Zheng, Y. Xi, H. Huang, L. L. Wu, Z. H. Lin","doi":"10.1039/B107714G","DOIUrl":"https://doi.org/10.1039/B107714G","url":null,"abstract":"A novel ZnO (zinc oxide)–PANI (polyaniline) composite film on PATP (ρ-aminothiophenol)/Au was prepared by electrochemical-assembly (ECA) and sol–gel technique, and this composite film shows excellent luminescent performance and high photoelectrochemical conversion efficiency, which can be industrially used for luminescent nanomaterials and treating wastewater containing methyl orange.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"36 1","pages":"100-101"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76148384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The heat of formation of dilute solution of lanthanide in bismuth was deduced from the activity coefficient of lanthanide in bismuth solution. The experimental values were compared with estimations of these values using Miedema's model. There is a simplified linear relation of the heat of formation of liquid Ln–Bi alloys with the 2/3 power of the metallic volumes of lanthanides, which is a useful tool for predicting the current unknown values. By introducing a correction constant in the Miedema's model, the predicted data agreed well with experimental data.
{"title":"The heat of formation of dilute solution of lanthanide in bismuth","authors":"J. Sheng, H. Yamana, H. Moriyama","doi":"10.1039/B104626H","DOIUrl":"https://doi.org/10.1039/B104626H","url":null,"abstract":"The heat of formation of dilute solution of lanthanide in bismuth was deduced from the activity coefficient of lanthanide in bismuth solution. The experimental values were compared with estimations of these values using Miedema's model. There is a simplified linear relation of the heat of formation of liquid Ln–Bi alloys with the 2/3 power of the metallic volumes of lanthanides, which is a useful tool for predicting the current unknown values. By introducing a correction constant in the Miedema's model, the predicted data agreed well with experimental data.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"1 1","pages":"63-65"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88164641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pranav Dalal, J. Knickelbein, A. Haymet, F. Sönnichsen, J. Madura
Antifreeze proteins (AFPs) are a group of structurally very diverse proteins with the unique capability of inhibiting ice crystal growth. Although significant progress has been made in the identification of different families of these proteins, the molecular mechanism of their action is unclear. The previously postulated mechanism of hydrogen bonding between the threonine residues of AFP and the water molecules in the ice surface has been disproved by mutation studies with non-polar residues. Currently, the mechanism of antifreeze activity cannot be fully understood from experimental or computational studies. Computational modeling studies have examined protein–ice interactions, mostly in vacuo. These studies have neglected the effects of the water phase. It has been shown that the vacuum is a very poor approximation for the water properties. Thus, to gain an insight into the molecular mechanism of these proteins we have computationally modeled a more realistic system comprising of AFP Type I from winter flounder (HPLC6), water and ice without any constraints. The results from this study show that the protein forms hydrogen bonds with the water molecules in the ice/water interfacial region. However, a comparison of the results with the protein in water simulations shows that there is no significant gain of hydrogen bonds for protein in the interfacial region compared to in the solvent. These results support the hypothesis that hydrogen bonding is not the primary reason for interaction of HPLC6 with the ice/water interfacial region.
{"title":"Hydrogen bond analysis of Type 1 antifreeze protein in water and the ice/water interface","authors":"Pranav Dalal, J. Knickelbein, A. Haymet, F. Sönnichsen, J. Madura","doi":"10.1039/B101331I","DOIUrl":"https://doi.org/10.1039/B101331I","url":null,"abstract":"Antifreeze proteins (AFPs) are a group of structurally very diverse proteins with the unique capability of inhibiting ice crystal growth. Although significant progress has been made in the identification of different families of these proteins, the molecular mechanism of their action is unclear. The previously postulated mechanism of hydrogen bonding between the threonine residues of AFP and the water molecules in the ice surface has been disproved by mutation studies with non-polar residues. Currently, the mechanism of antifreeze activity cannot be fully understood from experimental or computational studies. Computational modeling studies have examined protein–ice interactions, mostly in vacuo. These studies have neglected the effects of the water phase. It has been shown that the vacuum is a very poor approximation for the water properties. Thus, to gain an insight into the molecular mechanism of these proteins we have computationally modeled a more realistic system comprising of AFP Type I from winter flounder (HPLC6), water and ice without any constraints. The results from this study show that the protein forms hydrogen bonds with the water molecules in the ice/water interfacial region. However, a comparison of the results with the protein in water simulations shows that there is no significant gain of hydrogen bonds for protein in the interfacial region compared to in the solvent. These results support the hypothesis that hydrogen bonding is not the primary reason for interaction of HPLC6 with the ice/water interfacial region.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"30 1","pages":"32-36"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87523260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The communication presents a numerical test of the three most popular methods used for direct inversion of the highly resolved IR and MW spectra of diatomic systems: (A) the numerical techniques such as those described by Coxon (J. A. Coxon and P. G. Hajigeorgiou, J. Mol. Spectrosc., 1991, 150, 1, ; J. A. Coxon, J. Mol. Spectrosc., 1992, 150, 274, ), Bernath (J. M. Campbell, M. Dulick, D. Klapstein, J. B. White and P. F. Bernath, J. Chem. Phys., 1993, 99, 8379, ; H. G. Hedderich, M. Dulick and P. F. Bernath, J. Chem. Phys., 1993, 99, 8363, ; M. Dulick, K. Q. Zhang, B. Guo and P. F. Bernath, J. Mol. Spectrosc., 1998, 188, 14, ), Le Roy (J. Y. Seto, R. J. Le Roy, J. Verges and C. Amiot, J. Chem. Phys., 2000, 113, 3067, ) and their co-workers; (B) the analytical approach developed by Ogilvie (J. F. Ogilvie, J. Phys. B, 1994, 27, 47, ); and (C) its improved version, called deformational self-consistent (DS-c) procedure, proposed by Molski (M. Molski, J. Phys. Chem., 1999, 103, 5269, ; M. Molski, Chem. Phys. Lett., 1999, 306, 88, ; M. Molski, Chem. Phys. Lett., 2001, 342, 293, ). The results obtained for the test molecule LiH X 1 Σ + indicate that the energy levels and radial parameters generated by Ogilvie's Radiatom program are not sufficiently accurate for use in external applications.
{"title":"A comparison of numerical and analytical approaches for reduction of rotational and vibration–rotational spectra of diatomic molecules to parameters of radial functions","authors":"J. A. Coxon, M. Molski","doi":"10.1039/B104631B","DOIUrl":"https://doi.org/10.1039/B104631B","url":null,"abstract":"The communication presents a numerical test of the three most popular methods used for direct inversion of the highly resolved IR and MW spectra of diatomic systems: (A) the numerical techniques such as those described by Coxon (J. A. Coxon and P. G. Hajigeorgiou, J. Mol. Spectrosc., 1991, 150, 1, ; J. A. Coxon, J. Mol. Spectrosc., 1992, 150, 274, ), Bernath (J. M. Campbell, M. Dulick, D. Klapstein, J. B. White and P. F. Bernath, J. Chem. Phys., 1993, 99, 8379, ; H. G. Hedderich, M. Dulick and P. F. Bernath, J. Chem. Phys., 1993, 99, 8363, ; M. Dulick, K. Q. Zhang, B. Guo and P. F. Bernath, J. Mol. Spectrosc., 1998, 188, 14, ), Le Roy (J. Y. Seto, R. J. Le Roy, J. Verges and C. Amiot, J. Chem. Phys., 2000, 113, 3067, ) and their co-workers; (B) the analytical approach developed by Ogilvie (J. F. Ogilvie, J. Phys. B, 1994, 27, 47, ); and (C) its improved version, called deformational self-consistent (DS-c) procedure, proposed by Molski (M. Molski, J. Phys. Chem., 1999, 103, 5269, ; M. Molski, Chem. Phys. Lett., 1999, 306, 88, ; M. Molski, Chem. Phys. Lett., 2001, 342, 293, ). The results obtained for the test molecule LiH X 1 Σ + indicate that the energy levels and radial parameters generated by Ogilvie's Radiatom program are not sufficiently accurate for use in external applications.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"19 1","pages":"96-99"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84514910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Dedonder-Lardeux, D. Grosswasser, C. Jouvet, S. Martrenchard
The dynamics of excited state indole–(NH 3 ) n clusters has been investigated with two-color two-photon ionization. Mass spectra recorded with delayed ionization indicate that a hydrogen transfer reaction indole(S 1 )–(NH 3 ) n → C 8 H 6 N • + NH 4 (NH 3 ) n – 1 occurs for n = 3, 4, 5.
兴奋国家indole的dynamics——(NH 3)集群一直在调查双面离子。弥撒光谱和delayed recorded ionization indicate that a氢转移反应indole S(1)——(NH 3) n→C 8 H 6 + n•NH 4 (NH) n—1 occurs为n = 3, 4, 5。
{"title":"Dissociative hydrogen transfer in indole–(NH3)n clusters","authors":"C. Dedonder-Lardeux, D. Grosswasser, C. Jouvet, S. Martrenchard","doi":"10.1039/B100573L","DOIUrl":"https://doi.org/10.1039/B100573L","url":null,"abstract":"The dynamics of excited state indole–(NH 3 ) n clusters has been investigated with two-color two-photon ionization. Mass spectra recorded with delayed ionization indicate that a hydrogen transfer reaction indole(S 1 )–(NH 3 ) n → C 8 H 6 N • + NH 4 (NH 3 ) n – 1 occurs for n = 3, 4, 5.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"4 1","pages":"21-23"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76092696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transition path sampling is a numerical technique to compute transition rates between two stable states without having to assume a priori information about a dividing surface. However, when there are many different pathways to go from one stable state to another, for example, when there are many saddle points in the free energy surface, it can be difficult to sample all possible pathways within the timescale of a single simulation. In this work, we demonstrate the use of parallel tempering to overcome this problem.
{"title":"On the efficient sampling of pathways in the transition path ensemble","authors":"T. Vlugt, B. Smit","doi":"10.1039/B009865P","DOIUrl":"https://doi.org/10.1039/B009865P","url":null,"abstract":"Transition path sampling is a numerical technique to compute transition rates between two stable states without having to assume a priori information about a dividing surface. However, when there are many different pathways to go from one stable state to another, for example, when there are many saddle points in the free energy surface, it can be difficult to sample all possible pathways within the timescale of a single simulation. In this work, we demonstrate the use of parallel tempering to overcome this problem.","PeriodicalId":20106,"journal":{"name":"PhysChemComm","volume":"111 1","pages":"11-17"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73353198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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