Synthesis and characterization of tetracyanoquinodimethane polyesters

The synthesis of a polyester containing TCNQ units covalently bound to the polymer molecule by the 1ow-temperature-solution polycondensation of adipyl chloride with 2,5-bis-(2'-hydroxyethoxy)-7,7,8,8-tetracyanoquinodimethane is described. The TCNQ polyester is stable to air and water in its 0 and -1 oxidation states and can be readily dissolved in organic solvents so that film formation from solution is possible. The films can be rendered insoluble in organic solvents by a simple baking procedure which has been investigated in a preliminary way. The TCNQ polyester can be reversibly reduced to its radical anion and dianion in solution or as a film on an electrode surface. The potentials for the two one electron reduction steps in acetonitri1e-TBABF4 solution were measured by cyclic voltammetry to be E^0/-_{½= 0.06v and E^-/2-½ = -0.39v vs. SCE. The UV-visible spectrum of the TCNQ polyester showed absorptions at 408 nm (a = 52,900 cm³/g) and 430 nm (a = 53,000 cm ³/g) in acetonitrile solution and the radical anion of the TCNQ polyester showed absorptions at 445 nm (a = 44,000 cm³/g), 675 nm (a = 5,300 cm³ /g), 728 nm (a = 18,500 cm³/g), and 812 nm (a = 34,500 cm³/g) in acetonitri1e-TBABF4 solution.}

The low temperature polycondensation of a model monomer, 2,5-bis-(2'-hydroxyethoxy) benzene with adipyl chloride in N,Ndimethylacetamide solution was also studied and the preparation of the first high molecular weight products from the reaction of an aliphatic diacid chloride with an aliphatic did is reported. The effects of monomer concentration, reaction time, and reaction temperature on the viscosity of the products of this polyesterification are discussed. The synthesis of the TCNQ diol (2,5-bis-(2'-hydroxyethoxy)-7,7,8,8- tetracyanoquinodimethane) was studied in some detail and modifications in the procedure are reported which allow a nearly sixfold increase in the yield for the overall synthesis to be obtained over the previously reported results. Synthesis of the previously unreported dihydro derivative of the TCNQ diol (2,5-bis-(2'-hydroxyethoxy)-7,8- dihydro-7,7,8,8-tetracyanoquinodimethane) is also described and an initial study of the reduction of TCNQ with mercaptoacetic acid is reported.