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Hiroyuki Higuchi - One of the best experts on this subject based on the ideXlab platform.
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Orientation and Substituent Effects on the Properties of the Diacetylene-Group Connected Octaethylporphyrin-Dihexylbithiophene Derivatives (OEP-DHBTh-X) Carrying Electron-Withdrawing Groups
Bulletin of the Chemical Society of Japan, 2007Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Takashi Nishihara, Takuya Matsukihira, Hiroki Nakashima, Hiroyuki HiguchiAbstract:Orientational isomers of the Octaethylporphyrin–dihexylbithiophene (OEP–DHBTh) derivatives connected with a diacetylene linkage were synthesized, with various electron-withdrawing substituents X at...
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synthesis and properties of the Octaethylporphyrin dihexylbithiophene pyridine system oep dhbth py connected with diacetylene linkage proton mediated and heat driven spectral changes
Tetrahedron Letters, 2006Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Takuya Matsukihira, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–pyridine system (OEP–DHBTh–Py) connected with the diacetylene linkage were synthesized. The spectral measurements were performed under neutral and acidic conditions, clearly proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–Py but also their proton-mediated spectral changes.
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synthesis and structural and electronic properties of the Octaethylporphyrin dihexylbithiophene fullerene derivatives oep dhbth c60 connected with diacetylene linkage
Tetrahedron Letters, 2005Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Azusa Naoe, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–fullerene derivative (OEP–DHBTh–C 60 ) connected with the diacetylene linkage were synthesized. The electronic and electrochemical properties were studied, proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–C 60 but also their molecular motional behaviors evidently.
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Synthesis and structural and electronic properties of the Octaethylporphyrin–dihexylbithiophene–fullerene derivatives (OEP–DHBTh–C60) connected with diacetylene linkage
Tetrahedron Letters, 2005Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Azusa Naoe, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–fullerene derivative (OEP–DHBTh–C 60 ) connected with the diacetylene linkage were synthesized. The electronic and electrochemical properties were studied, proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–C 60 but also their molecular motional behaviors evidently.
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syntheses and electronic properties of the nickel and palladium complexes of the Octaethylporphyrin m1 dihexylbithiophene n Octaethylporphyrin m2 system oep m1 dhbth n oep m2 connected with the diacetylene linkage a methodology for molecular design o
Tetrahedron, 2004Co-Authors: Naoto Hayashi, Miho Murayama, Kazumine Mori, Akihito Matsuda, Emiko Chikamatsu, Keita Tani, Keiko Miyabayashi, Mikio Miyake, Hiroyuki HiguchiAbstract:Abstract The palladium complexes of highly extended π-electronic conjugation system, Octaethylporphyrin(Pd)–(dihexylbithiophene) n –Octaethylporphyrin(Pd) [OEP(Pd)–(DHBTh) n –OEP(Pd), n =1–6], were synthesized, in which all the chromophores are connected with diacetylene linkage. The unsymmetrical derivatives of OEP(Ni)–DHBTh–OEP(Pd) were also successfully synthesized. Electronic properties of these symmetrical and unsymmetrical complexes were conclusively described, as compared with those of OEP(Ni)–(DHBTh) n –OEP(Ni). Based on the structure elements, a methodical guiding principle for molecular design of the particular electronic structure will be proposed.
Subrata Sinha - One of the best experts on this subject based on the ideXlab platform.
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Ground state charge transfer complex formation of some metalloporphyrins with aromatic solvents: Further theoretical and experimental investigations
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017Co-Authors: Mihir Ghosh, Koushik Majhi, Prajna Mukherjee, Somnath Chowdhury, Bikash C. Gupta, Subrata SinhaAbstract:Abstract In our earlier work (Chem. Phys. Letts. 592 (2014) 149–154), a new broad band was observed in the near infrared region (700–900 nm) of the steady state absorption spectra of some metalloporphyrins (zinc tetraphenylporphyrin, zinc Octaethylporphyrin and magnesium Octaethylporphyrin) in aromatic solvents (chlorobenzene, 1,2-dichlorobenzene, benzonitrile, benzene and toluene) at high concentrations (~ 10 − 4 mol L − 1 ). The band was ascribed to be due to ground state charge transfer complexation between solute and solvent molecules. In the present work, density functional theory calculations are carried out to study the possibility of such ground state charge transfer complex formation between zinc tetraphenylporphyrin and four aromatic solvents viz., benzene, toluene, chlorobenzene and benzonitrile with 1:1 and 2:1 solvent-solute stoichiometries. Also, we determined the association constants for the ground state charge transfer complex formation of zinc tetraphenylporphyrin and zinc Octaethylporphyrin with two aromatic solvents (benzene and benzonitrile) by Benesi–Hildebrand method.
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Fluorescence quenching of 9-cyanoanthracene by metallo-Octaethylporphyrins in cyanobenzene
Journal of Porphyrins and Phthalocyanines, 2015Co-Authors: Mihir Ghosh, Aruna K. Mora, Sukhendu Nath, Biswajit Gopal Roy, Koushik Majhi, Subrata SinhaAbstract:Investigations are carried out on the nature of photoinduced electron transfer reactions within some metallo-Octaethylporphyrin (zinc Octaethylporphyrin and magnesium Octaethylporphyrin) donors and acceptor 9-cyanoanthracene in cyanobenzene at 300 K by steady state and time-resolved spectroscopic methods. Acceptor is selectively excited at 366 nm and 374 nm for steady state and time-resolved measurements, respectively, where donor metalloporphyrins possess negligible absorbance. Evidence is found for simultaneous occurrence of Forster's type singlet–singlet energy transfer process along with electron transfer. High exergonic values of Gibbs free energy change for both forward and back electron transfer reactions indicate the possibility of occurrences of these two consecutive processes in the Marcus inverted region.
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Solvatochromic Stokes shift and determination of excited state dipole moments of free base and zinc Octaethylporphyrin
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2015Co-Authors: Mihir Ghosh, Subrata SinhaAbstract:Abstract Solvent effects on the photophysical properties of free base Octaethylporphyrin and zinc Octaethylporphyrin are investigated at the ambient temperature (300 K). Steady state electronic absorption and emission spectra of the porphyrins are recorded in different organic solvents of varying polarity. By using solvatochromic Stokes shift method, the dipole moments associated with the first excited singlet states of the presently used porphyrin molecules are determined for the first time, to the best of our knowledge, from Lippert–Mataga, Bakhshiev and Reichardt equations. The dipole moments associated with the singlet ground state of the porphyrin molecules are calculated theoretically by using density functional theory (DFT) method by adopting B3LYP/6–31G(d,p) level using Gaussian 03 package. Moreover, some other photophysical properties (fluorescence quantum yield, fluorescence lifetime, decay rates, etc.) of the porphyrins are measured in different solvents of varying polarity.
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Ground state charge transfer complex formation of some metalloporphyrins with aromatic solvents
Chemical Physics Letters, 2014Co-Authors: Mihir Ghosh, Subrata SinhaAbstract:Abstract Porphyrin derivatives are known to have absorption spectra in the visible region (400–700 nm). In the present Letter, a new (to the best of our knowledge) broad band is reported in the NIR region (700–900 nm) of the absorption spectra of zinc tetraphenylporphyrin, zinc Octaethylporphyrin and magnesium Octaethylporphyrin in aromatic solvents at high concentrations (∼10−4 mol/L). The broad absorption band in the NIR region is ascribed to be due to ground state charge transfer complex formation between the presently used metalloporphyrins and aromatic solvents.
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Photoinduced electron transfer in metallo-Octaethylporphyrin (donor)–2-nitrofluorene (acceptor) systems in polar acetonitrile liquid medium
Journal of Photochemistry and Photobiology A: Chemistry, 2014Co-Authors: Mihir Ghosh, Aruna K. Mora, Sukhendu Nath, Alakananda Hajra, Subrata SinhaAbstract:Abstract The possible role of photoinduced electron transfer is investigated in the fluorescence quenching of the donors metallo-Octaethylporphyrins (zinc Octaethylporphyrin and magnesium Octaethylporphyrin) in presence of the acceptor 2-nitrofluorene in polar acetonitrile liquid medium by using steady state and time-resolved techniques at the ambient temperature (300 K). The donors are selectively excited at the Q band (S 1 state), where 2-nitrofluorene has negligible absorbance. The observed bimolecular fluorescence quenching rate constants for the present donor–acceptor systems from steady state as well as time-resolved fluorescence quenching data are of the order of 10 10 L/(mol s) (less than the diffusion-controlled limit of 1.9 × 10 10 L/(mol s)). The moderately negative values of Gibbs free energy change (Δ G °) indicate that photoinduced electron transfer from the metallo-porphyrins to 2-nitrofluorene in acetonitrile solvent is possible upon photoexcitation of the former molecules. Moreover, the fluorescence quenching rates for both the donor–acceptor systems obtained from Marcus theory agree quite well with the observed values from fluorescence quenching measurements (especially time-resolved measurements).
Laurent Ruhlmann - One of the best experts on this subject based on the ideXlab platform.
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Photovoltaic properties of supramolecular assemblies obtained by incorporation of Preysler's type polyoxometalate in a polycationic copolymer of porphyrin
Electrochimica Acta, 2018Co-Authors: Zhaohui Huo, Rana Farha, Michel Goldmann, Antoine Bonnefont, Yiming Liang, Eric Saint-aman, Christophe Bucher, Laurent RuhlmannAbstract:Poly-zinc-Octaethylporphyrin/P5W30 films have been obtained through incorporation of Preyssler-type polyoxometalate ions, namely [NaP5W30O110] 14-(P5W30) into zinc Octaethylporphyrin/viologen-based polymers (poly-ZnOEP) films. The latter has been achieved through a metathesis reaction involving exchange of the initial counter ions (PF6-) of the positively charged poly-ZnOEP by P5W30. The investigated polymers involve ZnOEP units covalently linked through either dicationic mono-viologen or through tetracationic bis-viologen spacers. These copolymers have been characterized by UV/Vis spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, AFM and by electrochemical impedance spectroscopy. Formation of the polymers through electropolymerization of viologen and porphyrin building blocks was monitored by EQCM. QCM was also used to study the exchange of PF6-by [NaP5W30O110] 14-. The photovoltaic performances under visible light irradiation have also been investigated by photocurrent transient measurements carried out under visible illumination.
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Synthesis and characterization of Lindqvist-type polyoxometalate–porphyrin copolymers
Electrochimica Acta, 2015Co-Authors: Zhaohui Huo, Rana Farha, Michel Goldmann, Bernold Hasenknopf, Zang Dejin, Yang Shu, Laurent RuhlmannAbstract:Hybrid polyoxometalate-porphyrin copolymeric films were obtained by the electrooxidation of 5, 15-ditolyl porphyrin (H2T2P) and zinc-β-Octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates TBA2[V6O13{(OCH2)3CNHCO(4-C5H4N)}2] (Py-POM-Py). The resulting films have been characterized by UV–visible absorption spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and electrochemistry. Electrochemical quartz crystal microbalance was employed to investigate the copolymer mass.
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Synthesis and characterization of conjugated Dawson-type polyoxometalate-porphyrin copolymers
Dalton Transactions, 2013Co-Authors: Iban Azcarate, Rana Farha, Michel Goldmann, Bernold Hasenknopf, Iftikhar Ahmed, Xiaoxia Wang, Emmanuel Lacôte, Laurent RuhlmannAbstract:Hybrid polyoxometalate-porphyrin copolymeric films were obtained by the electro-oxidation of zinc Octaethylporphyrin (ZnOEP) in the presence of a Dawson type polyoxophosphovanadotungstate bearing two pyridyl groups (POM(py)(2)). The synthesis of a series of POM(py)(2) consisting of [P2W15V3O62](9-) functionalized with diol-amide or triol moieties, as well as the characterization of the copolymers are presented.
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Synthesis and Photocatalytic Properties of Mixed Polyoxometalate-Porphyrin Copolymers Obtained from Anderson-Type Polyoxomolybdates
Langmuir, 2010Co-Authors: Delphine Schaming, Clémence Allain, Rana Farha, Michel Goldmann, Sylvie Lobstein, Alain Giraudeau, Bernold Hasenknopf, Laurent RuhlmannAbstract:Hybrid polyoxometalate-porphyrin copolymeric films are obtained by the electro-oxidation of zinc Octaethylporphyrin (ZnOEP) and zinc 5,15-dipyridinium Octaethylporphyrin (5,15-ZnOEP(py)(2)(2+)) in the presence of the polyoxometalate [MnMo(6)O(18)\(OCH(2))(3)CNHCO(4-C(5)H(4)N)\(2)](3-) (Py-POM-Py). These films allow the photocatalytic reduction of Ag(2)(I)SO(4) under visible irradiation in air in the presence of propan-2-ol at the 2D interface between water and the copolymeric films. The formation of metallic Ag(0) nanowires and triangular nanosheets is observed.
Mihir Ghosh - One of the best experts on this subject based on the ideXlab platform.
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Ground state charge transfer complex formation of some metalloporphyrins with aromatic solvents: Further theoretical and experimental investigations
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017Co-Authors: Mihir Ghosh, Koushik Majhi, Prajna Mukherjee, Somnath Chowdhury, Bikash C. Gupta, Subrata SinhaAbstract:Abstract In our earlier work (Chem. Phys. Letts. 592 (2014) 149–154), a new broad band was observed in the near infrared region (700–900 nm) of the steady state absorption spectra of some metalloporphyrins (zinc tetraphenylporphyrin, zinc Octaethylporphyrin and magnesium Octaethylporphyrin) in aromatic solvents (chlorobenzene, 1,2-dichlorobenzene, benzonitrile, benzene and toluene) at high concentrations (~ 10 − 4 mol L − 1 ). The band was ascribed to be due to ground state charge transfer complexation between solute and solvent molecules. In the present work, density functional theory calculations are carried out to study the possibility of such ground state charge transfer complex formation between zinc tetraphenylporphyrin and four aromatic solvents viz., benzene, toluene, chlorobenzene and benzonitrile with 1:1 and 2:1 solvent-solute stoichiometries. Also, we determined the association constants for the ground state charge transfer complex formation of zinc tetraphenylporphyrin and zinc Octaethylporphyrin with two aromatic solvents (benzene and benzonitrile) by Benesi–Hildebrand method.
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Fluorescence quenching of 9-cyanoanthracene by metallo-Octaethylporphyrins in cyanobenzene
Journal of Porphyrins and Phthalocyanines, 2015Co-Authors: Mihir Ghosh, Aruna K. Mora, Sukhendu Nath, Biswajit Gopal Roy, Koushik Majhi, Subrata SinhaAbstract:Investigations are carried out on the nature of photoinduced electron transfer reactions within some metallo-Octaethylporphyrin (zinc Octaethylporphyrin and magnesium Octaethylporphyrin) donors and acceptor 9-cyanoanthracene in cyanobenzene at 300 K by steady state and time-resolved spectroscopic methods. Acceptor is selectively excited at 366 nm and 374 nm for steady state and time-resolved measurements, respectively, where donor metalloporphyrins possess negligible absorbance. Evidence is found for simultaneous occurrence of Forster's type singlet–singlet energy transfer process along with electron transfer. High exergonic values of Gibbs free energy change for both forward and back electron transfer reactions indicate the possibility of occurrences of these two consecutive processes in the Marcus inverted region.
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Solvatochromic Stokes shift and determination of excited state dipole moments of free base and zinc Octaethylporphyrin
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2015Co-Authors: Mihir Ghosh, Subrata SinhaAbstract:Abstract Solvent effects on the photophysical properties of free base Octaethylporphyrin and zinc Octaethylporphyrin are investigated at the ambient temperature (300 K). Steady state electronic absorption and emission spectra of the porphyrins are recorded in different organic solvents of varying polarity. By using solvatochromic Stokes shift method, the dipole moments associated with the first excited singlet states of the presently used porphyrin molecules are determined for the first time, to the best of our knowledge, from Lippert–Mataga, Bakhshiev and Reichardt equations. The dipole moments associated with the singlet ground state of the porphyrin molecules are calculated theoretically by using density functional theory (DFT) method by adopting B3LYP/6–31G(d,p) level using Gaussian 03 package. Moreover, some other photophysical properties (fluorescence quantum yield, fluorescence lifetime, decay rates, etc.) of the porphyrins are measured in different solvents of varying polarity.
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Ground state charge transfer complex formation of some metalloporphyrins with aromatic solvents
Chemical Physics Letters, 2014Co-Authors: Mihir Ghosh, Subrata SinhaAbstract:Abstract Porphyrin derivatives are known to have absorption spectra in the visible region (400–700 nm). In the present Letter, a new (to the best of our knowledge) broad band is reported in the NIR region (700–900 nm) of the absorption spectra of zinc tetraphenylporphyrin, zinc Octaethylporphyrin and magnesium Octaethylporphyrin in aromatic solvents at high concentrations (∼10−4 mol/L). The broad absorption band in the NIR region is ascribed to be due to ground state charge transfer complex formation between the presently used metalloporphyrins and aromatic solvents.
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Photoinduced electron transfer in metallo-Octaethylporphyrin (donor)–2-nitrofluorene (acceptor) systems in polar acetonitrile liquid medium
Journal of Photochemistry and Photobiology A: Chemistry, 2014Co-Authors: Mihir Ghosh, Aruna K. Mora, Sukhendu Nath, Alakananda Hajra, Subrata SinhaAbstract:Abstract The possible role of photoinduced electron transfer is investigated in the fluorescence quenching of the donors metallo-Octaethylporphyrins (zinc Octaethylporphyrin and magnesium Octaethylporphyrin) in presence of the acceptor 2-nitrofluorene in polar acetonitrile liquid medium by using steady state and time-resolved techniques at the ambient temperature (300 K). The donors are selectively excited at the Q band (S 1 state), where 2-nitrofluorene has negligible absorbance. The observed bimolecular fluorescence quenching rate constants for the present donor–acceptor systems from steady state as well as time-resolved fluorescence quenching data are of the order of 10 10 L/(mol s) (less than the diffusion-controlled limit of 1.9 × 10 10 L/(mol s)). The moderately negative values of Gibbs free energy change (Δ G °) indicate that photoinduced electron transfer from the metallo-porphyrins to 2-nitrofluorene in acetonitrile solvent is possible upon photoexcitation of the former molecules. Moreover, the fluorescence quenching rates for both the donor–acceptor systems obtained from Marcus theory agree quite well with the observed values from fluorescence quenching measurements (especially time-resolved measurements).
Naoto Hayashi - One of the best experts on this subject based on the ideXlab platform.
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Orientation and Substituent Effects on the Properties of the Diacetylene-Group Connected Octaethylporphyrin-Dihexylbithiophene Derivatives (OEP-DHBTh-X) Carrying Electron-Withdrawing Groups
Bulletin of the Chemical Society of Japan, 2007Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Takashi Nishihara, Takuya Matsukihira, Hiroki Nakashima, Hiroyuki HiguchiAbstract:Orientational isomers of the Octaethylporphyrin–dihexylbithiophene (OEP–DHBTh) derivatives connected with a diacetylene linkage were synthesized, with various electron-withdrawing substituents X at...
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synthesis and properties of the Octaethylporphyrin dihexylbithiophene pyridine system oep dhbth py connected with diacetylene linkage proton mediated and heat driven spectral changes
Tetrahedron Letters, 2006Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Takuya Matsukihira, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–pyridine system (OEP–DHBTh–Py) connected with the diacetylene linkage were synthesized. The spectral measurements were performed under neutral and acidic conditions, clearly proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–Py but also their proton-mediated spectral changes.
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synthesis and structural and electronic properties of the Octaethylporphyrin dihexylbithiophene fullerene derivatives oep dhbth c60 connected with diacetylene linkage
Tetrahedron Letters, 2005Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Azusa Naoe, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–fullerene derivative (OEP–DHBTh–C 60 ) connected with the diacetylene linkage were synthesized. The electronic and electrochemical properties were studied, proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–C 60 but also their molecular motional behaviors evidently.
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Synthesis and structural and electronic properties of the Octaethylporphyrin–dihexylbithiophene–fullerene derivatives (OEP–DHBTh–C60) connected with diacetylene linkage
Tetrahedron Letters, 2005Co-Authors: Naoto Hayashi, Keiko Miyabayashi, Mikio Miyake, Azusa Naoe, Hiroyuki HiguchiAbstract:Abstract Orientational isomers of the Octaethylporphyrin–dihexylbithiophene–fullerene derivative (OEP–DHBTh–C 60 ) connected with the diacetylene linkage were synthesized. The electronic and electrochemical properties were studied, proving that the orientation of DHBTh affects not only the electronic structures of OEP–DHBTh–C 60 but also their molecular motional behaviors evidently.
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syntheses and electronic properties of the nickel and palladium complexes of the Octaethylporphyrin m1 dihexylbithiophene n Octaethylporphyrin m2 system oep m1 dhbth n oep m2 connected with the diacetylene linkage a methodology for molecular design o
Tetrahedron, 2004Co-Authors: Naoto Hayashi, Miho Murayama, Kazumine Mori, Akihito Matsuda, Emiko Chikamatsu, Keita Tani, Keiko Miyabayashi, Mikio Miyake, Hiroyuki HiguchiAbstract:Abstract The palladium complexes of highly extended π-electronic conjugation system, Octaethylporphyrin(Pd)–(dihexylbithiophene) n –Octaethylporphyrin(Pd) [OEP(Pd)–(DHBTh) n –OEP(Pd), n =1–6], were synthesized, in which all the chromophores are connected with diacetylene linkage. The unsymmetrical derivatives of OEP(Ni)–DHBTh–OEP(Pd) were also successfully synthesized. Electronic properties of these symmetrical and unsymmetrical complexes were conclusively described, as compared with those of OEP(Ni)–(DHBTh) n –OEP(Ni). Based on the structure elements, a methodical guiding principle for molecular design of the particular electronic structure will be proposed.