Functionalized Tetracyanoquinodimethane-type Electron Acceptors: Suitable Precursors for D-σ-A Materials

Several new 7,7,8,8-tetracyanoquinodimethane-type electron acceptors funetionalized with carboxylic acid or alcohol groups have been synthesized in moderate yields using three rather general routes. Two involved condensation reactions of malononitrile and ketones and the other proceeded through a 1,4-bis[dicyano(trimethylsiloxy)methyl]benzene. Some of the alcoholfunctionalized products were coupled with electron-donor isocyanates to afford novel D-σ-A (electron Donor-σ bridge-electron Acceptor) materials. 1. Introduction 2. Initial Synthetic Approaches to D-σ-A Materials 2.1. 7,7,8,8-Tetracyanoquinodimethane-2-acetic and -2-propanoic Acids 2.2. 5-Bromo-2-(2-hydroxyethoxy)-7,8,8,8-tetracyanoquinodimethane and 1,4,5,8-Tetrathiafulvalene-2-carboxylic Acid Derivatives 3. D-σ-A Materials from 5-Bromo-2-(2-hydroxyethoxy)-7,7,8,8-tetracyanoquinodimethane and 4-Dialkylaminophenyl or 4-Dodecyloxyphenyl Isocyanates 4. D-σ-A Materials from 2-(Hydroxymethyl)-11,11,12,12-tetracyano-9,10-anthraquinodimethane 5. 2-(2-Hydroxyethoxy)-7,7,8,8-tetracyanoquinodimethane 6. Bicyclic Tetracyanoquinodimethanes 6.1. 6-(Hydroxymethyl)-9,9,10,10-tetracyano-1,4-naphthoquinodimethane 6.2. Attempted Synthesis of 6-Hydroxy-5,6,7,8-tetrahydro-9,9,10,10-tetracyano-1,4-naphthoquinodimethane and 6-Hydroxy-9,9,10,10-tetracyano-1,4-napthoquinodimethane 6.3. Attempted Synthesis of 2-Hydroxy-8,8,9,9-tetracyanoindane-4,7-quinodimethane 7. Conclusion