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Photochemistry in Organic Synthesis

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (31 March 2010) | Viewed by 94278

Special Issue Editor

Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
Interests: catalysis and photocatalysis; chemical emergent systems for environment, energy, and fine chemistry; physical-organic chemistry; chemistry and materials science; spectroscopic techniques; advanced oxidation processes; solar fuels; nanotechnology and nanoscience; biophysics and biochemistry; chemical education and science communication; chemical engineering
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Special Issue Information

Dear Colleagues,

Photochemistry in Organic Synthesis concerns any type of useful chemical reaction that can by initiated by one electronic excited state of an organic molecule, generated after irradiation of a suitable system in the UV or visible region. In our days, because of environmental concerns, conversion to a highly functional compound by a photochemical useful reaction needs to be encompassed with a high selectivity to minimize waste. Thus, in this issue in addition to the traditional fields of electronic excited state reactivity and conventional photoinduced electron transfer activation, attention will be given to the enormous potential of photocatalysis as a tool for sustainable organic synthesis. Since radiation sources, optical materials and spectroscopic analytical tools are rapidly evolving, technological aspects as photochemical reactor engineering will be also covered.

Dr. Joaquim Luís Faria
Guest Editor

Keywords

  • electronic photo-excited states
  • energy transfer
  • photocatalysis
  • photochemical organic synthesis
  • photochemistry
  • photoinduced electron transfer
  • selective photo-oxidation
  • selective photo-reduction
  • semiconductor photocatalysis

Published Papers (8 papers)

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Research

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800 KiB  
Article
Syntheses, Characterization, and Photo-Hydrogen-Evolving Properties of Tris(2,2'-bipyridine)ruthenium(II) Derivatives Tethered to an H2-Evolving (2-phenylpyridinato)platinum(II) Unit
by Masayuki Kobayashi, Shigeyuki Masaoka and Ken Sakai
Molecules 2010, 15(7), 4908-4923; https://doi.org/10.3390/molecules15074908 - 14 Jul 2010
Cited by 23 | Viewed by 10120
Abstract
With the aim of developing new molecular devices having higher photo-hydrogen-evolving activity, Pt(ppy)ClX units (ppy = 2-phenylpyridinate, X = Cl- or DMSO; DMSO = dimethylsulfoxide) have been employed as an H2-evolving site, as the catalytic activity of [Pt(ppy)Cl2] [...] Read more.
With the aim of developing new molecular devices having higher photo-hydrogen-evolving activity, Pt(ppy)ClX units (ppy = 2-phenylpyridinate, X = Cl- or DMSO; DMSO = dimethylsulfoxide) have been employed as an H2-evolving site, as the catalytic activity of [Pt(ppy)Cl2]- was confirmed to be higher than those of other mononuclear platinum(II) complexes. In the present study, two new heterodinuclear Ru(II)Pt(II) complexes, produced by condensation of [Ru(bpy)2(5-amino-phen)]2+ (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) with [Pt(cppy)Cl2]- and Pt(cppy)(DMSO)Cl (cppy = 9-carboxy-phenylpyridinate), respectively, have been prepared and their photo-hydrogen-evolving activities have been evaluated in detail. The ineffectiveness of these systems as photo-hydrogen-evolving molecular devices are interpreted in terms of their negative driving forces for the photoinduced electron transfer from the triplet MLCT excited state of the Ru chromophore to the p*(ppy) orbital of the catalyst moiety. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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252 KiB  
Article
Photochemical Synthesis of Nucleoside Analogues from Cyclobutanones: Bicyclic and Isonucleosides
by Mileina Jaffer, Abdelaziz Ebead and Edward Lee-Ruff
Molecules 2010, 15(6), 3816-3828; https://doi.org/10.3390/molecules15063816 - 26 May 2010
Cited by 11 | Viewed by 7190
Abstract
The preparation of two nucleoside analogues are reported. Both syntheses involve a key photochemical ring-expansion of cyclobutanones to an oxacarbene and its subsequent scavenging by 6-chloropurine. The synthesis of a bicyclic (locked) purine starts from a oxabicycloheptanone with a hydroxymethyl pendant. The preparation [...] Read more.
The preparation of two nucleoside analogues are reported. Both syntheses involve a key photochemical ring-expansion of cyclobutanones to an oxacarbene and its subsequent scavenging by 6-chloropurine. The synthesis of a bicyclic (locked) purine starts from a oxabicycloheptanone with a hydroxymethyl pendant. The preparation of an isonucleoside uses a cyclobutanone with an α-substituted 6-chloropurine. Irradiation of the latter produces an isonucleoside and acyclic nucleoside analogues. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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413 KiB  
Article
Probing the Dynamics of Solvation and Structure of the OH- Ion in Aqueous Solution from Picosecond Transient Absorption Measurements
by Olivier Poizat and Guy Buntinx
Molecules 2010, 15(5), 3366-3377; https://doi.org/10.3390/molecules15053366 - 07 May 2010
Cited by 4 | Viewed by 7825
Abstract
The reaction of intracomplex proton transfer (44BPY-....HO-H) ® 44BPYH. + OH- that follows the photoreduction of 4,4’-bipyridine (44BPY) into its anion radical 44BPY- in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is investigated in acetonitrile-water mixtures by using picosecond transient [...] Read more.
The reaction of intracomplex proton transfer (44BPY-....HO-H) ® 44BPYH. + OH- that follows the photoreduction of 4,4’-bipyridine (44BPY) into its anion radical 44BPY- in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is investigated in acetonitrile-water mixtures by using picosecond transient absorption. The dependence of the appearance kinetics of the 44BPYH. radical on the water content reveals a highly diffusional proton transfer process that is controlled by the dynamics of solvation of the released hydroxide ion. The results are interpreted on the basis of a two-step mechanism where an intermediate solvation complex (44BPYH.)OH-(H2O)3 is formed first before evolving toward a final four-water hydration structure OH-(H2O)4. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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71 KiB  
Article
Influence of Solvent, Electron Acceptors and Arenes on Photochemical Decarboxylation of Free Carboxylic Acids via Single Electron Transfer (SET)
by Yasuharu Yoshimi, Shota Hayashi, Keisuke Nishikawa, Yoshiki Haga, Kousuke Maeda, Toshio Morita, Tatsuya Itou, Yutaka Okada, Nobuyuki Ichinose and Minoru Hatanaka
Molecules 2010, 15(4), 2623-2630; https://doi.org/10.3390/molecules15042623 - 12 Apr 2010
Cited by 37 | Viewed by 8919
Abstract
Single electron transfer (SET)-photochemical decarboxylation of free carboxylic acids was performed in a polar solvent using several arenes such as phenanthrene, naphthalene, 1-methylnaphthalene, biphenyl, triphenylene, and chrysene in the presence of various electron acceptors such as 1,2-, 1,3-, and 1,4-dicyanobenzenes, methyl 4-cyanobenzoate, and [...] Read more.
Single electron transfer (SET)-photochemical decarboxylation of free carboxylic acids was performed in a polar solvent using several arenes such as phenanthrene, naphthalene, 1-methylnaphthalene, biphenyl, triphenylene, and chrysene in the presence of various electron acceptors such as 1,2-, 1,3-, and 1,4-dicyanobenzenes, methyl 4-cyanobenzoate, and 1,4-dicyanonaphthalene. The decarboxylation reaction was influenced by the arenes, electron acceptors, and solvent. The best result was achieved by the photoreaction using biphenyl and 1,4-dicyanonaphthalene in aqueous acetonitrile. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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Review

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461 KiB  
Review
Photochemistry of Flavonoids
by Miroslav Sisa, Susan L. Bonnet, Daneel Ferreira and Jan H. Van der Westhuizen
Molecules 2010, 15(8), 5196-5245; https://doi.org/10.3390/molecules15085196 - 02 Aug 2010
Cited by 141 | Viewed by 13710
Abstract
Flavonoids and their photochemical transformations play an important role in biological processes in nature. Synthetic photochemistry allows access to molecules that cannot be obtained via more conventional methods. This review covers all published synthetic photochemical transformations of the different classes of flavonoids. It [...] Read more.
Flavonoids and their photochemical transformations play an important role in biological processes in nature. Synthetic photochemistry allows access to molecules that cannot be obtained via more conventional methods. This review covers all published synthetic photochemical transformations of the different classes of flavonoids. It is first comprehensive review on the photochemistry of flavonoids. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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294 KiB  
Review
Photochemical Oxidative Cyclisation of Stilbenes and Stilbenoids—The Mallory-Reaction
by Kåre B. Jørgensen
Molecules 2010, 15(6), 4334-4358; https://doi.org/10.3390/molecules15064334 - 14 Jun 2010
Cited by 201 | Viewed by 16668
Abstract
After Mallory described in 1964 the use of iodine as catalyst for the photochemical cyclisation of stilbenes, this reaction has proven its effectiveness in the synthesis of phenanthrenes, other PAHs and phenacenes with a surprisingly large selection of substituents. The “early age” of [...] Read more.
After Mallory described in 1964 the use of iodine as catalyst for the photochemical cyclisation of stilbenes, this reaction has proven its effectiveness in the synthesis of phenanthrenes, other PAHs and phenacenes with a surprisingly large selection of substituents. The “early age” of the reaction was reviewed by Mallory in 1984in a huge chapter in the Organic Reactions series, but the development has continued. Alternative conditions accommodate more sensitive substituents, and isomers can be favoured by sacrificial substituents. Herein the further developments and applications of this reaction after 1984 are discussed and summarized. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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248 KiB  
Review
Photochemical Transformations of Tetrazole Derivatives: Applications in Organic Synthesis
by Luís Miguel Teodoro Frija, Amin Ismael and Maria Lurdes Santos Cristiano
Molecules 2010, 15(5), 3757-3774; https://doi.org/10.3390/molecules15053757 - 25 May 2010
Cited by 103 | Viewed by 13904
Abstract
Tetrazoles remain a challenge to photochemists. Photolysis leads to cleavage of the tetrazolyl ring, may involve various photodegradation pathways and may produce a diversity of photoproducts, depending on the structure and conformational flexibility of the substituents and the possibility of tautomerism. If the [...] Read more.
Tetrazoles remain a challenge to photochemists. Photolysis leads to cleavage of the tetrazolyl ring, may involve various photodegradation pathways and may produce a diversity of photoproducts, depending on the structure and conformational flexibility of the substituents and the possibility of tautomerism. If the photochemistry of tetrazoles is considered within the frame of synthetic applications the subject is even more challenging, since the ultimate goal is to achieve selectivity and high yield. In addition, the photoproducts must remain stable and allow isolation or trapping, in order to be used in other reactions. This review summarises the photochemical transformations of tetrazole derivatives that can be used as effective synthetic routes to other compounds. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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3063 KiB  
Review
Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores
by Haifeng Yu and Takaomi Kobayashi
Molecules 2010, 15(1), 570-603; https://doi.org/10.3390/molecules15010570 - 26 Jan 2010
Cited by 72 | Viewed by 14336
Abstract
Photoresponsive block copolymers (PRBCs) containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular [...] Read more.
Photoresponsive block copolymers (PRBCs) containing azobenzenes and other chromophores can be easily prepared by controlled polymerization. Their photoresponsive behaviors are generally based on photoisomerization, photocrosslinking, photoalignment and photoinduced cooperative motions. When the photoactive block forms mesogenic phases upon microphase separation of PRBCs, supramolecular cooperative motion in liquid-crystalline PRBCs enables them to self-organize into hierarchical structures with photoresponsive features. This offers novel opportunities to photocontrol microphase-separated nanostructures of well-defined PRBCs and extends their diverse applications in holograms, nanotemplates, photodeformed devices and microporous films. Full article
(This article belongs to the Special Issue Photochemistry in Organic Synthesis)
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