Special Issue "New Trends in Photochemistry"

Guest Editor
Prof. Dr. Axel G. Griesbeck
Department of Chemistry, University of Cologne, Greinstr. 4, D-50939 Koeln, Germany
Website: http://www.oc.uni-koeln.de/griesbeck/englisch1.htm
E-Mail: griesbeck@uni-koeln.de
Interests: photooxygenation of organic compounds; photocycloaddition reactions; photodecarboxylation; photoisomerization; photoinduced electron transfer; photochemical macrocyclization reactions; new photochemical reactors and technologies

Dear Colleagues,

Photochemical reactions are versatile processes for inorganic and organic syntheses. Synthesis using light as reagent and producing complex molecules from simple starting materials is exemplary realized in natural photosynthesis. Mankind still struggles for an efficient molecular system that mimics the natural process. In order to harvest light energy and to transform it into chemical energy, photochemical reactions have to be studied and optimized for synthetic applications. In recent years, photocatalysis has regained momentum because it combines the well established concepts of metalcatalysis and organocatalysis with the ideas of photoinduced electron transfer.  Altogether, photo redox catalysis will be one of the major topics in modern photochemistry of the next decades. Nonetheless, also traditional photochemical reactions such as photocycloadditions and -cyclizations,
photochemical rearrangements, photoreductions, photooxidations and -oxygenations, photoinduced group transfer reactions and applications of photoremovable protecting groups, photochromic systems or photodegradation processes have to be studied and develop in the future
in order to satisfy the needs for a more sustainable synthetic chemistry.

This special issue of Molecules welcomes previously unpublished manuscripts covering all aspects of photochemical reactions including their design, product assessment, methodology development and applications.

Prof. Dr. Axel G. Griesbeck
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).

• photocycloadditions
• photochemical rearrangements
• photoreduction
• photooxidation
• photooxygenation
• photocatalysis
• photochemical electron transfer
• photoredox catalysis

Type of Paper: Review 
Title: Coordination Programming of Photofunctional Molecules 
Authors: Ryota Sakamoto, Shinpei Kusaka, Mikihiro Hayashi, Michihiro Nishikawa and Hiroshi Nishihara 
Affiliation: Department of Chemistry, School of Science, The University of Tokyo, Japan 
Abstract: This review article treats our recent achievements relating to photofunctional molecules. Chapter 1 treats E-Z photoisomerization of dimethyl bis(arylethynyl)fumarate/maleate to which redox-active donor sites (ferrocene, triarylamine, and N-phenylcarbazole) are appended (Chem. Eur. J. 2012, in press; Chem. Eur. J. 2008, 14, 6978; Angew. Chem. Int. Ed. 2006, 45, 4793). The photochromism is accompanied by switching of electronic communication between the redox-active donor sites in the one-electron oxidized mixed-valent states. Chapter 2 describes our new findings on Pechmann dye, which was first synthesized in 1882. New synthetic procedures for Pechmann dye using dimethyl bis(arylethynyl)fumarate as a starting material gives rise to its new structural isomer (J. Am. Chem. Soc. 2011, 133, 14518). We also demonstrate potentiality of a donor-acceptor-donor type of Pechmann dye in organic electronics. Chapter 3 discloses a new concept of photoisomerization. Pyrirylpyrimidine-copper complexes undergo a ring inversion that can be modulated by the redox state of the copper center. In combination with an intermolecular photoelectron transfer (PET) initiated by the metal-to-ligand charge transfer (MLCT) transition of the Cu(I) state, we realize photonic regulation of the ring inversion (J. Am. Chem. Soc. 2012, 134, 10543). Chapter 4 reports on the first examples of heteroleptic bis(dipyrrinato)zinc(II) complexes (Chem. Asian J. 2012, 7, 907). Conventional homoleptic bis(dipyrrinato)zinc(II) complexes suffered from low fluorescence quantum yields, whereas the heteroleptic ones feature bright fluorescence even in polar solvents.

Type of Paper: Review
Title: Potential Surfaces and Quantum Yield of Photochromic Diarylethene
Authors: Shin Nakamura and Kingo Uchida
Affiliation: RIKEN and Ryukoku University, Japan
Abstract: Photochromic diarylethes (DAE) are one of the most promissing systems towards future molecular electronics. Two categories exist among the derivatives of DAE. Numerous derivatives for both categories have been recently synthsized, and experimental quantum yields are reported. Reflecting theoretical potential enery surfaces and recent new experimental results, rational interpretation is presented.

Type of Paper: Review
Title: An Overview of Recent Development in Zeolite-Based Materials for Photocatalytic Applications
Authors: Elim Albiter, Salvador Alfaro, Sergio Flores, Omar Ríos-Bernÿ and Miguel A. Valenzuela
Affiliation: Lab. Catálisis y Materiales. ESIQIE-Instituto Politécnico Nacional. Zacatenco, 07738, Mexico D.F., Mexico
Abstract: In the last decade several review papers have been published concerning the photocatalytic activity of TiO2-supported zeolites (Anandan and Yoon), the photocatalytic reactivity of highly dispersed catalysts within zeolites (Matzuoka and Anpo), photochemical processes in zeolites, Dutta and Kim), among others. Curiously all the works mentioned above were published in the same year, 2003! Since then there has been a significant progress in obtaining new zeo-types compounds such as nanosized zeolites, zeolite composites, mesoporous zeolites. Thus aims to solve the diffusion limitations and use these materials in a wide range of photocatalytic reactions. This review will focus on the critical analysis of the applications of new zeolite-based materials, mainly semiconductor/zeolites composites, in photocatalytic reactions such as: pollutant degradation), green organic synthesis, water splitting and CO2 conversion. The study intends to complete work reported in the field, however, emphasis will be done on the decade 2002-2012, that is where new research and development on zeolites and photocatalysis have been done.