Chapter 1 From Resinous Tar to Molecular Baskets
1.1 The Resinous Tar ........................................... 1
1.2 Glistening Crystals: The Zinke Products .................... 5
1.3 More Crystals: The Niederl Products ........................ 9
1.4 Cyclic Tetramers: Proofs of Structure ..................... 11
1.5 The Petrolite Chapter ..................................... 15
1.6 Cyclic Tetramers and the Quest for Enzyme Mimics .......... 18
1.7 Unraveling the Literature ................................. 21
1.8 Nomenclature and Representation of the Calixarenes ........ 24
Chapter 2 Making the Baskets: Synthesis of Calixarenes
2.1 One-step, Base-induced Synthesis of Phenol-derived
Calixarenes ............................................... 27
2.1.1 Synthesis of p-tert-Butylcalixarenes ............... 27
2.1.2 Synthesis of Other p-Substituted Calixarenes ....... 31
2.2 One-step, Acid-catalyzed Synthesis of Calixarenes ......... 34
2.2.1 Phenol-derived Calixarenes ......................... 34
2.2.2 Resorcinol-derived Calixarenes ..................... 34
2.3 Multi-step Synthesis of Calixarenes ....................... 37
2.3.1 Non-convergent Stepwise Syntheses .................. 37
2.3.2 Convergent Stepwise Syntheses (Fragment
Condensation Procedure) ............................ 39
2.4 Synthesis of Calixarene-related Compounds ................. 45
2.4.1 Norcalixarenes and Homocalixarenes ................. 45
2.4.2 Oxacalixarenes, Azacalixarenes and
Thiacalixarenes .................................... 47
2.4.3 Homooxacalixarenes and Homoazacalixarenes .......... 49
2.4.4 Heterocalixarenes .................................. 51
2.5 Mechanism of Calixarene-forming Reactions ................. 53
2.5.1 Mechanism of the Base-induced Reaction ............. 53
2.5.2 Mechanism of the Acid-catalyzed Reaction ........... 59
2.6 Concluding Remarks ........................................ 60
Chapter 3 Proving the Baskets: The Characterization and
Properties of Calixarenes
3.1 Separation and Purification of Calixarenes ................ 62
3.2 X-Ray Crystallography: The Ultimate Proof of Structure .... 63
3.3 Physical Properties of Calixarenes ........................ 64
3.3.1 Melting Points ..................................... 64
3.3.2 Solubilities ....................................... 66
3.3.3 pKa Values ......................................... 66
3.4 Dipole Moments of Calixarenes ............................. 70
3.5 Spectral Properties of Calixarenes ........................ 70
3.5.1 Infrared Spectra ................................... 70
3.5.2 Ultraviolet Spectra ................................ 71
3.5.3 NMR Spectra ........................................ 72
3.5.4 Mass Spectra ....................................... 74
3.6 Concluding Remarks ........................................ 76
Chapter 4 Shaping the Baskets: Conformations of Calixarenes
4.1 Conformational Representation and Nomenclature ............ 77
4.2 Computational Studies of Calixarene Conformations ......... 81
4.3 Conformations of Calixarenes in the Solid State ........... 83
4.3.1 Calix[4]arenes ..................................... 83
4.3.2 Calix[5]arenes ..................................... 86
4.3.3 Calix[6]arenes ..................................... 86
4.3.4 Calix[7]arenes ..................................... 87
4.3.5 Calix[8]arenes ..................................... 87
4.3.6 Large Calixarenes .................................. 88
4.4 Conformations of Flexible Calixarenes in Solution ......... 88
4.4.1 Conformational Mobility of Calix[n]arenes .......... 88
4.4.1.1 Conformations of Calix[4]arenes ........... 89
4.4.1.2 Conformational Mobility of Calixarenes
Larger than Calix[4]arenes ................ 93
4.4.1.3 Conformational Mobility of
Oxacalixarenes and Azacalixarenes ......... 93
4.4.1.4 Conformational Mobility of
Calixresorcarenes and C-Substituted
Calixarenes ............................... 94
4.4.1.5 Conformational Mobility of
Thiacalixarenes ........................... 96
4.4.1.6 Conformational Mobility of Calixarene
Ethers, Deoxycalixarenes, Calixquinones
and Calixarenethiols ...................... 97
4.4.2 Pathways for Cone-cone Interconversion
of Calix[4]arenes .................................. 98
4.5 Conformationaly Immobile Calixarenes ...................... 99
4.5.1 Minimum Structural Requirements for
Conformational Immobility of Unbridged Calixarene
Ethers and Esters .................................. 99
4.5.1.1 Identification of Fixed Conformers ........ 99
4.5.1.2 Fully Etherified and Esterified
Calixarenes ............................... 99
4.5.1.3 Partially Etherified and Esterified
Calixarenes .............................. 103
4.5.1.4 Meta-substituted Calixarenes ............. 104
4.5.2 Conformational Immobilization via Bridging ........ 104
4.5.3 Conformational Freezing via Oxygen-Metal
Bridges ........................................... 107
4.6 Factors Governing the Conformational Outcome
of Derivatization ........................................ 109
4.6.1 O-Tetrasubstitution of Calix[4]arenes ............. 109
4.6.2 Mono-, Di- and Tri-O-substitution of
Calix[4]arenes .................................... 111
4.6.3 O-Substitution of Calix[5]arenes and
Calix[6]arenes .................................... 111
4.6.4 Calixarene Oxyanions .............................. 112
4.6.4.1 Calix[4]arene Oxyanions .................. 112
4.6.4.2 Calix[6]arene Oxyanions .................. 112
4.7 Chiral Calixarenes ....................................... 113
4.8 Concluding Remarks ....................................... 115
Chapter 5 Embroidering the Baskets: Introduction of
Functional Groups
5.1 Functionalization Involving the OH Groups ................ 116
5.1.1 Esterification .................................... 116
5.1.2 Etherification .................................... 118
5.1.2.1 With Simple Alkyl Halides ................ 118
5.1.2.2 With Functionalized Alkylating Agents .... 122
5.1.3 Endo Rim-bridged Calixarenes ...................... 123
5.1.4 Replacement of OH with H, N and S ................. 127
5.2 Modifying the Exo Rim of Calixarenes ..................... 129
5.2.1 General Overview .................................. 129
5.2.2 Halogenation, Nitration, Sulfonation and
Diazonium Coupling Routes ......................... 130
5.2.3 Alkylation (Including Chloromethylation) Route .... 133
5.2.4 Acylation and Aroylation Routes ................... 134
5.2.5 Arylation Reactions ............................... 135
5.2.6 Aminomethylation: The p-Quinonemethide Route ...... 135
5.2.7 p-Claisen Rearrangement Route ..................... 136
5.3 Functionalization of the Methylene Bridges ............... 138
5.4 Exo Rim-Bridged Calixarenes .............................. 140
5.5 Oxidation of Calixarenes ................................. 141
5.5.1 Calixquinones ..................................... 141
5.5.2 Spirodienones ..................................... 143
5.6 Reduction of Calixarenes ................................. 144
5.7 Selective Functionalization .............................. 145
5.8 Concluding Remarks ....................................... 146
Chapter 6 Combining the Baskets: Multi-Calixarenes
6.1 Calixarenes Intermolecularly Bridged by Covalent
Bonding .................................................. 148
6.1.1 Bridging via the Endo Rims ........................ 148
6.1.2 Bridging via the Exo Rims ......................... 150
6.1.3 Multi-Calixarenes and Calixarene Dendrimers ....... 152
6.2 Calixarenes Intermolecularly Bridged by Non-covalent
Bonding .................................................. 154
6.2.1 Dimeric Assemblies of Calixarenes ................. 154
6.2.2 Catenanes and Rotaxanes ........................... 157
6.2.3 Oligomeric and Polymeric Assemblies of
Calixarenes ....................................... 158
6.2.4 Calixarenes in Monolayers and Interfaces .......... 160
6.3 Calixarene Polymers ...................................... 162
6.4 Concluding Remarks ....................................... 163
Chapter 7 Filling the Baskets: Complex Formation with
Calixarenes
7.1 Solid State Complexes .................................... 164
7.2 Solution State Complexes of Metal Cations with Endo
Rim-substituted Calixarenes .............................. 171
7.2.1 Complexation with Parent Calixarenes .............. 172
7.2.2 Complexation with Endo Rim-substituted
Calixarenes ....................................... 173
7.2.2.1 Endo Rim Ethers .......................... 173
7.2.2.2 Endo Rim Esters ......................... 175
7.2.2.3 Endo Rim Ketones ......................... 176
7.2.2.4 Endo Rim Amides .......................... 177
7.2.2.5 Endo Rim Carboxylic Acids ................ 178
7.2.2.6 Endo Rim Phosphorus- and
Sulfur-containing Groups ................. 180
7.2.2.7 Nitrogen-containing Chelating Groups on
the Endo Rim ............................. 181
7.2.3 Calixcrowns ....................................... 182
7.2.4 Calixspherands .................................... 186
7.3 Solution State Complexes of Metal Cations with Exo
Rim-substituted Calixarenes .............................. 187
7.4 Anion Complexes with Calixarenes ......................... 188
7.5 Salt Complexes with Calixarenes .......................... 191
7.6 Solution State Complexes of Molecules with Calixarenes ... 193
7.6.1 Complexes with Molecular Cations .................. 193
7.6.2 Complexes with Neutral Molecules .................. 197
7.6.2.1 Complexes in Aqueous Solution ............ 197
7.6.2.2 Complexes in Non-aqueous Solution ........ 199
7.7 Gas Phase Complexes ...................................... 203
7.8 Theoretical Calculations ................................. 204
7.9 Templation ............................................... 204
7.9.1 Templation in Calixarene Synthesis ................ 204
7.9.2 Calixarenes as Templates .......................... 204
7.9.3 Templation in Conformational Phenomena ............ 205
7.9.4 Allosteric Effects ................................ 206
7.10 Concluding Remarks ....................................... 207
Chapter 8 Using the Baskets: Calixarenes in Action
8.1 Calixarenes for Separations .............................. 209
8.1.1 Separations of Ions ............................... 209
8.1.2 Separations of Molecules .......................... 210
8.2 Calixarenes as Sensors ................................... 211
8.2.1 Ion-and Molecule-selective Electrodes ............. 212
8.2.2 Field Effect Transistors .......................... 214
8.2.3 Chromogenic and Fluorescent Sensors ............... 216
8.2.4 Nonlinear Optical Compounds ....................... 218
8.2.5 Other Sensors ..................................... 220
8.3 Calixarenes as Catalysts ................................. 220
8.3.1 Biomimetic Catalysts .............................. 220
8.3.2 Non-biomimetic Catalysts .......................... 225
8.4 Calixarenes as Biomimetic and Physiological Compounds .... 228
8.5 Miscellaneous Applications ............................... 231
8.6 Patent Literature ........................................ 236
8.7 Concluding Remarks ....................................... 237
Appendices .................................................... 238
Author Index .................................................. 244
Subject Index ................................................. 261
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