http://www.mdpi.com/journal/molecules/special_issues/photochemistry/ 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. 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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this Open Access journal is 1400 CHF per accepted paper. http://www.mdpi.com/1420-3049/15/8/5196/ 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. http://www.mdpi.com/1420-3049/15/8/5196/ Mon, 02 Aug 2010 00:00:00 CEST Molecules 2010-08-02 15 8 Review 5196 5245 1420-3049 Photochemistry of Flavonoids 2010-08-02 doi: 10.3390/molecules15085196 Miroslav Sisa Susan L. Bonnet Daneel Ferreira Jan H. Van der Westhuizen http://www.mdpi.com/1420-3049/15/7/4908/ 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. http://www.mdpi.com/1420-3049/15/7/4908/ Wed, 14 Jul 2010 00:00:00 CEST Molecules 2010-07-14 15 7 Article 4908 4923 1420-3049 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 2010-07-14 doi: 10.3390/molecules15074908 Masayuki Kobayashi Shigeyuki Masaoka Ken Sakai http://www.mdpi.com/1420-3049/15/6/4334/ 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. http://www.mdpi.com/1420-3049/15/6/4334/ Mon, 14 Jun 2010 00:00:00 CEST Molecules 2010-06-14 15 6 Review 4334 4358 1420-3049 Photochemical Oxidative Cyclisation of Stilbenes and Stilbenoids—The Mallory-Reaction 2010-06-14 doi: 10.3390/molecules15064334 Jørgensen http://www.mdpi.com/1420-3049/15/6/3816/ 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. http://www.mdpi.com/1420-3049/15/6/3816/ Wed, 26 May 2010 00:00:00 CEST Molecules 2010-05-26 15 6 Article 3816 3828 1420-3049 Photochemical Synthesis of Nucleoside Analogues from Cyclobutanones: Bicyclic and Isonucleosides 2010-05-26 doi: 10.3390/molecules15063816 Jaffer Ebead Lee-Ruff http://www.mdpi.com/1420-3049/15/5/3757/ 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. http://www.mdpi.com/1420-3049/15/5/3757/ Tue, 25 May 2010 00:00:00 CEST Molecules 2010-05-25 15 5 Review 3757 3774 1420-3049 Photochemical Transformations of Tetrazole Derivatives: Applications in Organic Synthesis 2010-05-25 doi: 10.3390/molecules15053757 Frija Ismael Cristiano http://www.mdpi.com/1420-3049/15/5/3366/ 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. http://www.mdpi.com/1420-3049/15/5/3366/ Fri, 07 May 2010 00:00:00 CEST Molecules 2010-05-07 15 5 Article 3366 3377 1420-3049 Probing the Dynamics of Solvation and Structure of the OH- Ion in Aqueous Solution from Picosecond Transient Absorption Measurements 2010-05-07 doi: 10.3390/molecules15053366 Poizat Buntinx http://www.mdpi.com/1420-3049/15/4/2623/ 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. http://www.mdpi.com/1420-3049/15/4/2623/ Mon, 12 Apr 2010 00:00:00 CEST Molecules 2010-04-12 15 4 Article 2623 2630 1420-3049 Influence of Solvent, Electron Acceptors and Arenes on Photochemical Decarboxylation of Free Carboxylic Acids via Single Electron Transfer (SET) 2010-04-12 doi: 10.3390/molecules15042623 Yoshimi Hayashi Nishikawa Haga Maeda Morita Itou Okada Ichinose Hatanaka http://www.mdpi.com/1420-3049/15/1/570/ 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. http://www.mdpi.com/1420-3049/15/1/570/ Tue, 26 Jan 2010 00:00:00 CET Molecules 2010-01-26 15 1 Review 570 603 1420-3049 Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores 2010-01-26 doi: 10.3390/molecules15010570 Haifeng Yu Takaomi Kobayashi