The Viologens Physicochemical Properties, Synthesis and Applications of the Salts of 4,4'-Bipyridine

by Monk, Paul M. S.

• ISBN13: 9780471986034
• ISBN10: 0471986038
• Edition: 1st
• Format: Hardcover
• Copyright: 1999-01-07
• Publisher: WILEY

Summary

The Viologens Physicochemical Properties, Synthesis and Applications of the Salts of 4,4'-Bipyridine Paul M. S. Monk Manchester Metropolitan University, UK Viologens are salts of 4,4'-bipyridine and are used in such fields as herbicides, electrochromism, solar energy conversion, molecular electronics and supramolecular chemistry. The Viologens is a comprehensive overview of the nature and physicochemical properties of the viologens and details the science behind the applications. Following a broad, discursive and self contained introduction to viologen chemistry, subsequent chapters develop the theory and present a detailed review of the most important properties and concepts in this field. A chapter on viologen synthesis is also included. This book is aimed at researchers in physical and organic chemistry, physics, materials science, biology and environmental engineering.

Author Biography

Paul M. S. Monk received his PhD in the electrochemistry of novel electrochromic viologen species at Exeter University in 1989. A postdoctoral research fellow position (1989-91) at the University of Aberdeen, in Scotland, was followed by lecturing positions in Physical Chemistry at Manchester Polytechnic (1991-2) then Manchester Metropolitan University (1992-2007). He is currently employed as a Vicar in an inner-city parish in Oldham, Greater Manchester, UK.

Table of Contents

Introduction	xiii	(4)
Symbols and Abbreviations used in the Text	xvii
Chapter 1 Introduction and Overview	1	(31)
1.1 Introduction	2	(9)
1.1.1 The Three Common Redox Forms	3	(1)
1.1.1.1 Bipyridilium dications--bipm^(2+)	3	(1)
1.1.1.2 Bipyridilium radical cations--bipm^(+)	4	(5)
1.1.1.3 Di-reduced bipyridilium compounds--bipm^0	9	(1)
1.1.2 Other Bipyridilium Species	10	(1)
1.1.2.1 Di-hydrogen biypridilium compounds--h(2)bipm^0	10	(1)
1.1.2.2 Oxo-bipyridilium compounds	10	(1)
1.1.3 Polymeric Bipridilium Salts	11	(1)
1.1.4 Nuclear Substitution	11	(1)
1.2 Physical Properties of Bipyridilium Species	11	(7)
1.2.1 Radical Solubility	11	(2)
1.2.2 Dimerization of Bipyridilium Radical Cations	13	(2)
1.2.3 Adsorption	15	(1)
1.2.4 Association and Charge Transfer	16	(1)
1.2.5 Micelle Formation	16	(1)
1.2.6 Conductivity	17	(1)
1.3 Electron-transfer Reactions: Electrochemistry	18	(2)
1.3.1 The Comproportionation Reaction	19	(1)
1.4 Photochemistry	20	(1)
1.5 Applications of Bipyridilium Systems	20	(4)
1.5.1 Catalytic Production of Hydrogen from Water	20	(1)
1.5.2 Electrochromic Displays (ECDs)	21	(1)
1.5.3 Electron Mediation	21	(1)
1.5.4 Thin-film Mediators: Derivatised Electrodes for Preparative Electrochemistry	22	(1)
1.5.5 Phytotoxicity	23	(1)
1.5.6 Miscellaneous Uses of Bipyridilium Compounds	24	(1)
References	24	(8)
Chapter 2 Synthesis of Viologens	32	(23)
2.1 Pyridines	34	(1)
2.2 Bipyridine	34	(4)
2.2.1 Coupling Reactions with Sodium and its Alloys	35	(1)
2.2.2 Coupling Reactions with Zinc	36	(1)
2.2.3 Coupling Reactions with Nickel	36	(1)
2.2.4 Coupling Reactions with Magnesium	36	(1)
2.2.5 Coupling Reactions with Copper	36	(1)
2.2.6 Nuclear-substituted 4.4-Bipyridines	36	(2)
2.3 Viologen Dications	38	(5)
2.3.1 Dication from Quaternized 4.4-Bipyridine	38	(2)
2.3.2 Dication from Coupling of 1-Substituted Pyridinium Cations	40	(1)
2.3.3 Heteroatom Substitution at Nitrogen	41	(1)
2.3.3.1 Pyridinium N-Oxides	42	(1)
2.3.3.2 Pyridinium N-Imines and N-Nitroimine Compounds	42	(1)
2.4 Viologen Radical Cations	43	(1)
2.5 Di-reduced Viologen Compounds	43	(1)
2.6 Preparation of Viologen Polymers	44	(2)
2.7 Specimen Viologen Preparation Procedures	46	(6)
2.7.1 A Nuclear-Substituted Bipyridine: 2-Ethyl-4,4-Bipyridine	46	(1)
2.7.2 A Mono-Quaternized Bipyridine: 1-Benzyl-4-(4-Pyridyl)-Pyridinium Chloride	47	(1)
2.7.3 Methyl Viologen: 1,1'-Dimethyl-4,4'-Bipyridilium bis(Methosulphate)	48	(1)
2.7.4 1,1'Diheptyl-4,4'-Bipyridilium Dibromide	48	(1)
2.7.5 An Aryl-Substituted Viologen: 1,1'-bis (2,4-Dinitrophenyl)-4,4'-Bipyridilium Dichloride	49	(1)
2.7.6 An Aryl-Substituted Viologen Prepared by the Allen Reaction: 1,1'-bis (p-Cyanophenly) 4,4'-Bipyridilium Dichloride	49	(1)
2.7.7 A Cyclopyridinophane: Cyclobis (Parapheylene-4,4'-Bipyridilium) tetrakis (Perchlorate)	50	(1)
2.7.8 A Viologen Radical Cation: 1,1'-bis(p-Cyanophenyl)-4,4'-Bipyridilium Perchlorate Radical Cation	51	(1)
2.7.9 A Polyviologen: tetrakis(1',2',4',5'-Tetramethyl[1-(Methyl-4,4'-Bipyridilium)]Benzene) Tetrachloride Tetrabromide	51	(1)
References	52	(3)
Chapter 3 Spectroscopic Properties of Viologen Species	55	(10)
3.1 Electron Paramagnetic Resonance Spectroscopy	56	(2)
3.2 UV-Visible Spectroscopy	58	(1)
3.3 Vibrational Spectroscopy	59	(3)
3.4 Nuclear Magnetic Resonance Spectroscopy	62	(1)
References	63	(2)
Chapter 4 The Structure of Bipyridilium Species	65	(14)
4.1 The 1,1'-Dialkyl-4,4'-Bipyridilium Dication	65	(5)
4.2 Structure of CT adducts with TCNQ	70	(1)
4.3 The 1,1'-Diaryl-4,4'-Bipyridilium Dication	71	(1)
4.4 Structures of the Bipyridilium Radical Cation	72	(1)
4.5 Computed Structures of the Bipyridilium Dication and Radical Cation	73	(1)
4.6 4,4'-Bipyridine	74	(1)
4.7 Miscellaneous Structures: Cyclopyridinophanes and Use of 4,4'-Bipyridine as Bridging Ligand	75	(1)
References	76	(3)
Chapter 5 The Dication: Charge-transfer Equilibria	79	(36)
5.1 Introduction	80	(2)
5.2 Elementary Charge-transfer Theory	82	(5)
5.2.1 Parameters Obtained from CT Spectra	83	(3)
5.2.2 Determination of Charge-transfer Parameters	86	(1)
5.3 The Effects of Electrolyte Medium	87	(4)
5.3.1 Solvent Effects	87	(3)
5.3.2 The Effect of Ionic Strength	90	(1)
5.4 The Kinetics of Charge-transfer Complexation	91	(2)
5.5 Charge-transfer Complexes of Methyl Viologen	93	(12)
5.5.1 Solution-phase Complexation	93	(8)
5.5.2 Solid-state Complexes	101	(4)
5.6 Charge-transfer Complexes of Other Viologens than Methyl Viologen	105	(3)
5.6.1 Solution-phase Complexation	105	(1)
5.6.2 Solid-state Complexes	106	(1)
5.6.3 Intramolecular Charge Transfer	107	(1)
5.7 Intervalence Charge Transfer	108	(1)
5.8 Uses of Bipyridilium CT	109	(2)
5.8.1 Photo-excitation of a CT Band to from Radical Cation	109	(1)
5.8.2 Effect of CT on Biological Systems	110	(1)
5.8.3 Incorporation of Viologens in Zeolites	110	(1)
References	111	(4)
Chapter 6 The Radical Cation: Dimer Formation	115	(17)
6.1 Introduction: The Radical Cation	115	(1)
6.2 Dimerization of the Radical Cation	116	(1)
6.3 Thermodynamics of Dimerization	117	(4)
6.4 Kinetics of Dimerization	121	(3)
6.4.1 Kinetics of Dimer Dissociation	122	(2)
6.5 Dimerization and the Solid State	124	(1)
6.6 Structure of the Dimer	124	(6)
References	130	(2)
Chapter 7 The Di-reduced Bipyridilium Species: The Comproportionation Reaction	132	(16)
7.1 Introduction	132	(1)
7.2 Detection of the Comproportionation Reaction	133	(5)
7.2.1 Comproportionation Reactions: UV-Visible Spectroscopic Monitoring	133	(2)
7.2.2 Comproportionation Reactions: Raman Spectroscopic Monitoring	135	(1)
7.2.3 Comproportionation Reactions: Electrochemical Monitoring	135	(2)
7.2.4 Comproportionation Reactions: EPR Spectroscopic Monitoring	137	(1)
7.3 Thermodynamic Aspects of Comporportionation	138	(1)
7.4 Kinetic Aspects of Comproportionation	139	(1)
7.5 Mechanistic Aspects of Comproportionation	140	(6)
7.5.1 Background: Dimerization of the Radical Cation	140	(3)
7.5.2 Comproportionation with Dimer Formation Studied by RRDE	143	(1)
7.5.3 Comproportionation with Dimer Formation Studied by Spectroelectrochemistry	143	(1)
7.5.4 The Comproportionation Mechanism	144	(2)
References	146	(2)
Chapter 8 Adsorption of the Viologens	148	(13)
8.1 Introduction: Adsorption	148	(4)
8.2 Adsorption of Viologens on Metals	152	(5)
8.2.1 Adsorption on to Mercury	152	(2)
8.2.2 Adsorption of Viologens on Solid Metals	154	(3)
8.3 Role of Adsorption in the Mechanism of Electron Transfer	157	(1)
8.4 Adsorption of Viologens on Non-Metals	158	(1)
8.5 Adsorption of Viologens on Adsorbed Layers: Viologen Thin Films	158	(1)
References	159	(2)
Chapter 9 Electrochemistry and Electron-transfer Reactions	161	(47)
9.1 Introduction: Electrode Potentials	162	(20)
9.1.1 Correlations of E with Substituent Constants Sigma from Physical-Organic Chemistry	176	(6)
9.2 Dynamic Electrochemistry: Mechanism and Electrodeposition of Radical-cation Salts	182	(6)
9.3 Electron-transfer Theory: Electron-transfer to Viologen Redox states	188	(15)
9.3.1 Theory of Electron Transfer: Marcus Theory	188	(4)
9.3.2 Heterogeneous Rates of Electron Transfer,k(et) at an Electroded	192	(2)
9.3.3 Homogeneous Chemical Reduction of Bipm^(2+) Species	194	(2)
9.3.4 Homogeneous Chemical Oxidation of Bipm^(+) Species	196	(1)
9.3.5 Reduction of Bipm(2+) within an Ion Pair or Charge-transfer Complex; Intramolecular Electron Transfer	196	(1)
9.3.5.1 Electron transfer in Ion Pairs and Charge-Transfer Complexes	197	(4)
9.3.5.2 Intramolecular Electron Transfer	201	(5)
References	203	(5)
Chapter 10 Photochemistry of the Viologens and Solar-energy Conversion	208	(12)
10.1 Introduction	208	(1)
10.2 Photochemistry of Methyl Viologen	209	(1)
10.3 Photochemistry of Viologen Charge-transfer Complexes	210	(1)
10.3.1 Viologens in Solution	210	(1)
10.3.2 Viologens in the Solid State	211	(1)
10.4 Fluorescence of Viologen Species	211	(2)
10.5 Viologen-mediated Production of Molecular Hydrogen from Water	213	(4)
10.5.1 Photochemical Hydrogen Production from Di-reduced Methyl Viologen	217	(1)
10.6 Photochemistry at Solid Interfaces	217	(1)
References	217	(3)
Chapter 11 Electron Mediation, Herbicidal Activity and Toxicity	220	(19)
11.1 Introduction to Electron Mediation	220	(3)
11.2 Mediated Bio-electrochemistry	223	(6)
11.2.1 Cytochrome-c	225	(1)
11.2.2 Mediation of Ferredoxins and NAD-NADH	226	(1)
11.2.3 Reductase Enzymes	227	(1)
11.2.4 Immobilized Viologens as Mediators	228	(1)
11.2.5 Sensors Utilizing Electron Mediation	228	(1)
11.3 Viologens in Other Mediated Systems	229	(1)
11.3.1 Oxygen	229	(1)
11.4 Toxicity of Methyl Viologen	229	(4)
11.4.1 Phytotoxicity	229	(2)
11.4.2 Cytotoxicity	231	(2)
11.4.3 Reversal of the Paraquat Poisoning	233	(1)
11.4.4 Fatal Paraquat Poisoning	233	(1)
11.5 Toxicity of Other Viologens	233	(1)
References	234	(5)
Chapter 12 Electrochromism in Viologen-based Systems	239	(20)
12.1 Introduction: Electrochromism	239	(1)
12.2 Uses of Electrochromic Devices	240	(3)
12.3 The Design of Electrochromic Devices	243	(3)
12.4 Parameters Defining ECD Operation	246	(7)
12.4.1 Electrochrome Type	246	(1)
12.4.2 Contrast Ratio	247	(1)
12.4.3 Colouration Efficiency	248	(1)
12.4.4 Electrode Substrate	248	(1)
12.4.5 Response Time	248	(2)
12.4.6 Cycle Life	250	(1)
12.4.7 Write-Efficiency	250	(2)
12.4.8 Power Consumption	252	(1)
12.4.9 Polyelectrochromicity	252	(1)
12.5 Soluble-to-Insoluble Viologens for ECDS: Type-II Electrochromes	253	(3)
12.5.1 Inhibition of Viologen `Recrystallization'	254	(2)
References	256	(3)
Chapter 13 Solid-state Conductivity and use of Viologens in Molecular Electronics	259	(16)
13.1 Introduction: Conductivity	259	(5)
13.2 Conductivity of Viologen Systems	264	(6)
13.2.1 Conductivity of Viologen Redox Mixtures	265	(5)
13.3 Molecular Electronics of the Viologens	270	(3)
13.3.1 Applications Based on Conductivity Change	270	(2)
13.3.2 Molecular Electronics of Viologen-based Thin Films	272	(1)
References	273	(2)
Chapter 14 Supramolecular and Self Assembly Chemistry of the Viologens	275	(22)
14.1 Introduction	275	(2)
14.2 Simple Guest-Host Structures	277	(3)
14.2.1 Viologens as Guests	277	(1)
14.2.2 Viologens as Hosts: Cyclopyridinophanes	278	(2)
14.3 Catenanes	280	(2)
14.4 Rotaxanes	282	(8)
14.3.1 Pseudorotaxanes	288	(2)
14.4.2 Polyrotaxanes	290	(1)
14.5 Miscellaneous Self-assembly Structures	290	(2)
References	292	(5)
Chemical Index	297	(4)
Index	301