Xll CONTENTS 



III. Porphyrin Chemistry 47 



1 Introduction 47 



1.1 Historical 47 



1 .2 Occurrence of Porphyrins in Nature 48 



2 Structure of Biologically Important Porphyrins 49 



2.1 Definition and Side Chains of Various Porphyrins 49 



2.2 Nomenclature and Symbols 53 



2.3 Structural Isomerism 54 



2.4 Syntheses 56 



3 Individual Porphyrins 58 



3.1 Porphin 58 



3.2 Etioporphyrins 59 



3.3 Porphyrins with Two Carboxylic Acid Groups 59 



3.3.1 Mesoporphyrin IX 59 



3.3.2 Protoporphyrin IX 60 



3.3.3 Deuteroporphyrin IX 61 



3.3.4 Hematoporphyrin IX 61 



3.3.5 Porphyrins with Carbonyl Groups in Side Chains. 62 



3.4 Porphyrins with Four and More Carboxylic Acid Groups. . . 63 



3.4.1 Coproporphyrins 63 



3.4.2 Uroporphyrins 66 



3.4.3 Porphyrins with Five to Seven Carboxylic Acid 

 Groups 68 



4 Aspects of the Physical Chemistry 68 



4.1 Solubility and Acid-Base Character 68 



4.2 Adsorption and Surface Properties 70 



4.3 Light Absorption 71 



4.4 Fluorescence 76 



5 Porphyrinogens 77 



6 Stereochemistry and Fine Structure of Porphyrins 78 



6.1 Resonance 78 



6.2 X-ray Analysis of Phthalocyanins 80 



6.3 The Evidence against Resonance 83 



6.4 Absorption Spectra and Fine Structure of the Nucleus 84 



7 Methods of Isolation and Estimation of Porphyrins 85 



7.1 Isolation 85 



7.2 Estimation 87 



8 Tetrapyrrolic Ring Compounds Related to Porphyrins 89 



8.1 Azaporphyrins 89 



8.2 Oxyporphyrins 91 



9 Porphyrin Complex Salts 93 



IV. Bile Pigments 95 



1 Introduction 95 



1.1 Definition 95 



1.2 Structure 95 



1.3 Synthesis 99 



1.4 Stereochemistry 100 



2 Bile Pigment Classes and the Problem of Nomenclature 103 



2.1 Inadequacies of Present Nomenclature 103 



2.2 Systematic Nomenclatures 105 



