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Rajeev K Sinha - One of the best experts on this subject based on the ideXlab platform.
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building up water wire clusters Isomer selective ultraviolet and infrared spectra of jet cooled 2 aminopurine h2o n n 2 and 3
Journal of Physical Chemistry B, 2013Co-Authors: Simon Lobsiger, Rajeev K Sinha, Samuel LeutwylerAbstract:2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP·(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster Isomers in the 31200–33000 cm–1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm–1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two Isomers of the n = 2 and of two Isomers of the n = 3 cluster are identified. One n = 2 Isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other Isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH2 group. For 2-aminopurine·(H2O)3, one Isomer...
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vibronic spectra of jet cooled 2 aminopurine h2o clusters studied by uv resonant two photon ionization spectroscopy and quantum chemical calculations
Journal of Physical Chemistry A, 2011Co-Authors: Rajeev K Sinha, Simon Lobsiger, Maria Angela Trachsel, Samuel LeutwylerAbstract:For understanding the major- and minor-groove hydration patterns of DNAs and RNAs, it is important to understand the local solvation of individual nucleobases at the molecular level. We have investigated the 2-aminopurine·H2O monohydrate by two-color resonant two-photon ionization and UV/UV hole-burning spectroscopies, which reveal two Isomers, denoted A and B. The electronic spectral shift δν of the S1 ← S0 transition relative to bare 9H-2-aminopurine (9H-2AP) is small for Isomer A (−70 cm−1), while that of Isomer B is much larger (δν = −889 cm−1). B3LYP geometry optimizations with the TZVP basis set predict four cluster Isomers, of which three are doubly H-bonded, with H2O acting as an acceptor to a N—H or —NH2 group and as a donor to either of the pyrimidine N sites. The “sugar-edge” Isomer A is calculated to be the most stable form with binding energy De = 56.4 kJ/mol. Isomers B and C are H-bonded between the —NH2 group and pyrimidine moieties and are 2.5 and 6.9 kJ/mol less stable, respectively. Time...
Samuel Leutwyler - One of the best experts on this subject based on the ideXlab platform.
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building up water wire clusters Isomer selective ultraviolet and infrared spectra of jet cooled 2 aminopurine h2o n n 2 and 3
Journal of Physical Chemistry B, 2013Co-Authors: Simon Lobsiger, Rajeev K Sinha, Samuel LeutwylerAbstract:2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP·(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster Isomers in the 31200–33000 cm–1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm–1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two Isomers of the n = 2 and of two Isomers of the n = 3 cluster are identified. One n = 2 Isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other Isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH2 group. For 2-aminopurine·(H2O)3, one Isomer...
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vibronic spectra of jet cooled 2 aminopurine h2o clusters studied by uv resonant two photon ionization spectroscopy and quantum chemical calculations
Journal of Physical Chemistry A, 2011Co-Authors: Rajeev K Sinha, Simon Lobsiger, Maria Angela Trachsel, Samuel LeutwylerAbstract:For understanding the major- and minor-groove hydration patterns of DNAs and RNAs, it is important to understand the local solvation of individual nucleobases at the molecular level. We have investigated the 2-aminopurine·H2O monohydrate by two-color resonant two-photon ionization and UV/UV hole-burning spectroscopies, which reveal two Isomers, denoted A and B. The electronic spectral shift δν of the S1 ← S0 transition relative to bare 9H-2-aminopurine (9H-2AP) is small for Isomer A (−70 cm−1), while that of Isomer B is much larger (δν = −889 cm−1). B3LYP geometry optimizations with the TZVP basis set predict four cluster Isomers, of which three are doubly H-bonded, with H2O acting as an acceptor to a N—H or —NH2 group and as a donor to either of the pyrimidine N sites. The “sugar-edge” Isomer A is calculated to be the most stable form with binding energy De = 56.4 kJ/mol. Isomers B and C are H-bonded between the —NH2 group and pyrimidine moieties and are 2.5 and 6.9 kJ/mol less stable, respectively. Time...
Simon Lobsiger - One of the best experts on this subject based on the ideXlab platform.
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building up water wire clusters Isomer selective ultraviolet and infrared spectra of jet cooled 2 aminopurine h2o n n 2 and 3
Journal of Physical Chemistry B, 2013Co-Authors: Simon Lobsiger, Rajeev K Sinha, Samuel LeutwylerAbstract:2-Aminopurine (2AP) is an adenine analogue with a high fluorescence quantum yield in water solution, which renders it a useful real-time probe of DNA structure. We report the ultraviolet (UV) and infrared (IR) spectra of size-selected and jet-cooled 9H-2AP·(H2O)n clusters with n = 2 and 3. Mass- and species-specific UV/UV holeburning spectroscopy allows to separate the UV spectra of four cluster Isomers in the 31200–33000 cm–1 spectral region with electronic band origins at 31339, 31450, 31891, and 32163 cm–1. Using IR/UV depletion spectroscopy in combination with B3LYP calculated harmonic vibrational frequencies, the H-bonding topologies of two Isomers of the n = 2 and of two Isomers of the n = 3 cluster are identified. One n = 2 Isomer (denoted 2A) forms a water dimer chain between the N9H and N3 atoms at the sugar-edge site, the other Isomer (denoted 2D) binds one H2O at the sugar-edge site and the other at the trans-amino site between the N1 atom and the NH2 group. For 2-aminopurine·(H2O)3, one Isomer...
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vibronic spectra of jet cooled 2 aminopurine h2o clusters studied by uv resonant two photon ionization spectroscopy and quantum chemical calculations
Journal of Physical Chemistry A, 2011Co-Authors: Rajeev K Sinha, Simon Lobsiger, Maria Angela Trachsel, Samuel LeutwylerAbstract:For understanding the major- and minor-groove hydration patterns of DNAs and RNAs, it is important to understand the local solvation of individual nucleobases at the molecular level. We have investigated the 2-aminopurine·H2O monohydrate by two-color resonant two-photon ionization and UV/UV hole-burning spectroscopies, which reveal two Isomers, denoted A and B. The electronic spectral shift δν of the S1 ← S0 transition relative to bare 9H-2-aminopurine (9H-2AP) is small for Isomer A (−70 cm−1), while that of Isomer B is much larger (δν = −889 cm−1). B3LYP geometry optimizations with the TZVP basis set predict four cluster Isomers, of which three are doubly H-bonded, with H2O acting as an acceptor to a N—H or —NH2 group and as a donor to either of the pyrimidine N sites. The “sugar-edge” Isomer A is calculated to be the most stable form with binding energy De = 56.4 kJ/mol. Isomers B and C are H-bonded between the —NH2 group and pyrimidine moieties and are 2.5 and 6.9 kJ/mol less stable, respectively. Time...
Feihe Huang - One of the best experts on this subject based on the ideXlab platform.
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Cis–Trans Selectivity of Haloalkene Isomers in Nonporous Adaptive Pillararene Crystals
Journal of the American Chemical Society, 2019Co-Authors: Yujuan Zhou, Run Zhao, Feihe HuangAbstract:The separation of haloalkene cis–trans Isomers is difficult to achieve, yet highly desired in the chemical industry. Here, we report an energy-efficient adsorptive separation of 1,4-dichloro-2-butene (DCB) cis–trans Isomers using nonporous adaptive crystals of perethylated pillararenes. Adaptive perethylated pillar[6]arene (EtP6) crystals separate the trans-DCB Isomer from its cis Isomer with high selectivity while perethylated pillar[5]arene (EtP5) crystals adsorb cis–trans DCB Isomers without selectivity. The selectivity of EtP6 derives from the difference in the thermodynamic stabilities of guest-loaded EtP6 crystal structures upon capture of cis–trans DCB Isomers, while the structural similarity of guest-loaded EtP5 leads to the loss of selectivity. EtP6 is highly recyclable due to the reversible transformations between guest-free and guest-loaded structures.
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cis trans selectivity of haloalkene Isomers in nonporous adaptive pillararene crystals
Journal of the American Chemical Society, 2019Co-Authors: Yujuan Zhou, Run Zhao, Feihe HuangAbstract:The separation of haloalkene cis–trans Isomers is difficult to achieve, yet highly desired in the chemical industry. Here, we report an energy-efficient adsorptive separation of 1,4-dichloro-2-butene (DCB) cis–trans Isomers using nonporous adaptive crystals of perethylated pillararenes. Adaptive perethylated pillar[6]arene (EtP6) crystals separate the trans-DCB Isomer from its cis Isomer with high selectivity while perethylated pillar[5]arene (EtP5) crystals adsorb cis–trans DCB Isomers without selectivity. The selectivity of EtP6 derives from the difference in the thermodynamic stabilities of guest-loaded EtP6 crystal structures upon capture of cis–trans DCB Isomers, while the structural similarity of guest-loaded EtP5 leads to the loss of selectivity. EtP6 is highly recyclable due to the reversible transformations between guest-free and guest-loaded structures.
Yujuan Zhou - One of the best experts on this subject based on the ideXlab platform.
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Cis–Trans Selectivity of Haloalkene Isomers in Nonporous Adaptive Pillararene Crystals
Journal of the American Chemical Society, 2019Co-Authors: Yujuan Zhou, Run Zhao, Feihe HuangAbstract:The separation of haloalkene cis–trans Isomers is difficult to achieve, yet highly desired in the chemical industry. Here, we report an energy-efficient adsorptive separation of 1,4-dichloro-2-butene (DCB) cis–trans Isomers using nonporous adaptive crystals of perethylated pillararenes. Adaptive perethylated pillar[6]arene (EtP6) crystals separate the trans-DCB Isomer from its cis Isomer with high selectivity while perethylated pillar[5]arene (EtP5) crystals adsorb cis–trans DCB Isomers without selectivity. The selectivity of EtP6 derives from the difference in the thermodynamic stabilities of guest-loaded EtP6 crystal structures upon capture of cis–trans DCB Isomers, while the structural similarity of guest-loaded EtP5 leads to the loss of selectivity. EtP6 is highly recyclable due to the reversible transformations between guest-free and guest-loaded structures.
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cis trans selectivity of haloalkene Isomers in nonporous adaptive pillararene crystals
Journal of the American Chemical Society, 2019Co-Authors: Yujuan Zhou, Run Zhao, Feihe HuangAbstract:The separation of haloalkene cis–trans Isomers is difficult to achieve, yet highly desired in the chemical industry. Here, we report an energy-efficient adsorptive separation of 1,4-dichloro-2-butene (DCB) cis–trans Isomers using nonporous adaptive crystals of perethylated pillararenes. Adaptive perethylated pillar[6]arene (EtP6) crystals separate the trans-DCB Isomer from its cis Isomer with high selectivity while perethylated pillar[5]arene (EtP5) crystals adsorb cis–trans DCB Isomers without selectivity. The selectivity of EtP6 derives from the difference in the thermodynamic stabilities of guest-loaded EtP6 crystal structures upon capture of cis–trans DCB Isomers, while the structural similarity of guest-loaded EtP5 leads to the loss of selectivity. EtP6 is highly recyclable due to the reversible transformations between guest-free and guest-loaded structures.