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Author: J.L. Sessler Publisher: Elsevier ISBN: 0080535232 Category : Science Languages : en Pages : 533
Book Description
The porphyrins are a class of naturally-occurring macrocycles and are ubiquitous in our world. As such, they have been called the Pigments of Life. This auspicious designation reflects their importance in numerous biological functions. Indeed, life as we understand it relies on the full range of biological processes that are either performed by or catalyzed by porphyrin-containing proteins. Chlorophyll-containing photosynthetic reaction centers in plants, for instance, convert light energy into chemical energy while producing oxygen along the way. It is this oxygen, evolved from photosynthesis, that is transported, stored, and reduced by heme-containing proteins in many organisms, including mammals. Not surprisingly, therefore, these molecules remain of fundamental interest to chemists and biochemists. Indeed, they continue to be intensely investigated by researchers world-wide. Inspired by the importance of the porphyrins, a new research direction has emerged in recent years that is devoted to the preparation and study of non-porphyrin polypyrrole macrocycles. Here, the principal objectives have been to generate completely synthetic systems that bear some structural resemblance to naturally-occurring porphyrin derivatives while being quite different in their specific chemical makeup. Within this context, three different research directions have evolved, namely those involving the syntheses of contracted, isomeric, and expanded porphyrins, respectively. It is the chemistry of these systems that is the subject of this book. Because of the newness of the field, the emphasis of this book will be on synthesis and characterization (all work on porphyrin isomers and much of that associated with expanded porphyrins has only appeared in the last 10 years). One chapter on applications has, however, been included. Also, in the context of the preparative portions of the text, some efforts have been made to explain why various porphyrin analogue targets are of interest.
Author: J.L. Sessler Publisher: Elsevier ISBN: 0080535232 Category : Science Languages : en Pages : 533
Book Description
The porphyrins are a class of naturally-occurring macrocycles and are ubiquitous in our world. As such, they have been called the Pigments of Life. This auspicious designation reflects their importance in numerous biological functions. Indeed, life as we understand it relies on the full range of biological processes that are either performed by or catalyzed by porphyrin-containing proteins. Chlorophyll-containing photosynthetic reaction centers in plants, for instance, convert light energy into chemical energy while producing oxygen along the way. It is this oxygen, evolved from photosynthesis, that is transported, stored, and reduced by heme-containing proteins in many organisms, including mammals. Not surprisingly, therefore, these molecules remain of fundamental interest to chemists and biochemists. Indeed, they continue to be intensely investigated by researchers world-wide. Inspired by the importance of the porphyrins, a new research direction has emerged in recent years that is devoted to the preparation and study of non-porphyrin polypyrrole macrocycles. Here, the principal objectives have been to generate completely synthetic systems that bear some structural resemblance to naturally-occurring porphyrin derivatives while being quite different in their specific chemical makeup. Within this context, three different research directions have evolved, namely those involving the syntheses of contracted, isomeric, and expanded porphyrins, respectively. It is the chemistry of these systems that is the subject of this book. Because of the newness of the field, the emphasis of this book will be on synthesis and characterization (all work on porphyrin isomers and much of that associated with expanded porphyrins has only appeared in the last 10 years). One chapter on applications has, however, been included. Also, in the context of the preparative portions of the text, some efforts have been made to explain why various porphyrin analogue targets are of interest.
Author: Jonathan L. Sessler Publisher: Elsevier ISBN: 9780080420936 Category : Science Languages : en Pages : 546
Book Description
Paperback. The porphyrins are a class of naturally-occurring macrocycles and are ubiquitous in our world. As such, they have been called the Pigments of Life. This auspicious designation reflects their importance in numerous biological functions. Indeed, life as we understand it relies on the full range of biological processes that are either performed by or catalyzed by porphyrin-containing proteins. Chlorophyll-containing photosynthetic reaction centers in plants, for instance, convert light energy into chemical energy while producing oxygen along the way. It is this oxygen, evolved from photosynthesis, that is transported, stored, and reduced by heme-containing proteins in many organisms, including mammals. Not surprisingly, therefore, these molecules remain of fundamental interest to chemists and biochemists. Indeed, they continue to be intensely investigated by researchers world-wide.Inspired by the importance of the porphyrins, a new research di
Author: Karl Kadish Publisher: Academic Press ISBN: 9780123932006 Category : Science Languages : en Pages : 456
Book Description
Scientists in such fields as mathematics, physics, chemistry, biochemistry, biology, and medicine are currently involved in investigations of porphyrins and their numerous analogues and derivatives. Porphyrins are being used as platforms for the study of theoretical principles, as catalysts, as drugs, as electronic devices, and as spectroscopic probes in biology and medicine. The need for an up-to-date and authoritative treatise on the porphyrin system has met with universal acclaim amongst scientists and investigators. The Porphyrin Handbook represents a timely publication dealing with the recent chemistry, physics, biology, and medicine of porphyrins and related macrocycles. This publication will be a major reference source in this field for the new millennium. Editors are world-renowned experts in their particular fields of physical chemistry, bio-organic chemistry, and organometallic chemistry Consists of several thousand pages of articles written by internationally recognized experts Biological relevance of porphyrins is linked to their chemical, physical, and structural features Clear, concise, and uniform presentation with many hundreds of figures, tables and structural formulae Of interest to theorists, physicists, chemists, biochemists, biologists, and medical scientists
Author: M.P. Dobhal Publisher: Springer ISBN: 9783642416040 Category : Science Languages : en Pages : 0
Book Description
The porphyrins are an important class of naturally occurring macrocyclic compounds that play a very important role in the metabolism of living organisms. They have a universal biological distribution and were involved in the oldest metabolic phenomena on earth. Without porphyrins and their relative compounds, life as we know it would be impossible and therefore the knowledge of these systems and their excited states is essential in understanding a wide variety of biological processes, including oxygen binding, electron transfer, catalysis, and the initial photochemical step in photosynthesis. The objective of this volume is to present a full and critical spectral data coverage of the entire major fields relating to porphyrin isomers and expanded porphyrins, their precursors, catabolic derivatives, and related systems electronically.
Author: Saovalak Sripothongnak Publisher: ISBN: Category : Chemistry Languages : en Pages : 226
Book Description
"Porphyrin is an aromatic naturally occurring molecule that has important roles in biological systems such as light harvesting, electron transfer and oxygen transport. In addition, porphyrin has unusual coordination and electronic properties leading to many applications including as catalysts, advanced materials and photodynamic therapy agents. Because of these roles, porphyrins are some of the more studied fields in chemistry. In order to understand the role of the porphyrin macrocycle in its coordination and electronic properties, chemists have modified the structure of porphyrin either in skeletal or peripheral positions. As the result, porphyrin analogs and isomers of porphyrin, including contracted porphyrins, expanded porphyrins and heteroatom substituted porphyrins, have been synthesized. Azaporphyrins are porphyrin derivatives that are generated by the replacing of one or more meso sp2 hybridized carbon atoms with nitrogen atoms. These macrocycles exhibit unique coordination and electronic properties. The phthalocyanines are the best known azaprophyrins. Phthalocyanine was first prepared by Braun and Tcherniac in 1907. Phthalocyanine is well-known in the dye and pigment industry. There has been much research and development into molecules related to phthalocyanine. One such example is hemipoprhyrazine[sic]. Hemiporphyrazines are members of the phthalocyanine family that have been studied for over five decades. Hemiporphyazines have extremely different chemical and physical properties from phtalocyanine even though hemiporphyrazine is generated by replacing two isoindoline rings of phthalocyanine with alternate rings, such as pyridines. The hemiporphyrazine derivatives dicarbahemiporphyrazine and benziphthalocyanine were first synthesized in the 1950s by Linstead and Elvidge. Benziphthalocyanine and dicarbahemiporphyrazine are generated by replace one and two isoindoline unit of phthalocyanine with benzene ring, respectively. The presence of carbon atoms in the core of these macrocycles results in unusual coordination and electronic properties. Prior to 2006, the metallation of these adducts was not explored even though the free bases of dicarbahemiporphyrazine and benziphthalocyanine were prepared about 50 years earlier. This dissertation will describe the metal chemistry, including coordination, electronic and physical properties of several metal complexes of dicarbahemiporphyrazine and benziphthalocyanine including lithium and nickel. N-Confused porphyrin is a well studied porphyrin isomer. The structure of this ring is the same as normal porphyrin but with one pyrrole inverted such that there are three nitrogen atoms at the core and one nitrogen atom at the periphery of the macrocycle. Over the past fifteen years, a variety of metal complexes of N-confused porphyrin have been prepared, including iron, cobalt, manganese, nickel, copper and zinc. This dissertation will present the synthesis and the metal binding chemistry of the first lithium and chromium complexes of N-confused porphyrin."--Abstract.
Author: Raymond Peter Brinas Publisher: ISBN: Category : Electronic dissertations Languages : en Pages :
Book Description
The rational synthesis of meso-aryl substituted porphyrins and related macrocycles were investigated and their chelation behavior studied. 1. meso-Tetraarylporphyrins are one of the most studied synthetic porphyrins because of their various potential applications in medicinal and materials chemistry and biomimetics. The less studied 5,15-diphenylporphyrin (5,15-DPP) has found applications, for instance, in multi-porphyrin assemblies. The equally interesting and potentially useful cis-isomer to 5,15-DPP, 5,10-diphenylporphyrin (5,10-DPP) has not been described in the literature before. We have utilized the 2 + 2 methodology (condensation of two dipyrrolic units) to synthesize the novel compound 5,10-DPP. 2. meso-Triarylcorroles have become known only recently as the serendipitous side products of a pyrrole-benzaldehyde condensation reaction. We developed a rational, stepwise synthetic methodology to prepare meso-triarylcorroles. The key step in this method is the preparation of a triaryltetrapyrrane intermediate, which then is oxidatively cyclized to form the desired corrole. This synthetic method is applicable to the synthesis of both A3-type meso-substituted corroles and of A2B-type meso-substituted corroles. meso-Triarylcorroles reacted with silver(I) acetate and copper (II) acetate to form [meso-triarylcorrolato]Ag(III) and [meso-triarylcorrolato]Cu(III), respectively. The saddled structures of both complexes containing the metals in unusual oxidation states were established by NMR spectroscopy, mass spectrometry, X-ray crystallography and X-ray photoelectron spectroscopy. [meso-tritolylcorrolato]Cu(III) exhibited a spin equilibrium between the Cu(III) complex and the Cu(II) cation radical complex as observed by variable-temperature NMR spectroscopy. 3. Expanded (macrocycles containing a more than 18Ï€-electron system) and contracted (macrocycles containing less than 18Ï€-electron system) porphyrins are interesting because they may extend the rich coordination chemistry of the porphyrin macrocycle. Rational approaches were developed toward the synthesis of one novel expanded porphyrin (a pyrazole/pyrrole [26Ï€] expanded porphyrin hybrid system) and one imine-linked tripyrrolic contracted porphyrin. Although the target molecules could not be prepared, this work provided insights into the stepwise building of porphyrinic macrocycles.
Author: J.L. Sessler
Author: J.L. Sessler
Author: Jonathan L. Sessler
Author: Eric Allen Brucker
Author: M. P. Dobhal
Author: M. P. Dobhal
Author: Karl Kadish
Author: M.P. Dobhal
Author: Saovalak Sripothongnak
Author: Raymond Peter Brinas
Author: Geneva Ruth Peterson