Synthesis and characterisation of carboxylic acid and diphenylphosphine derivatives in the 1,3-diyne series: spectral properties of polydiacetylene carboxylates

Symmetrically substituted 1,3-diynes containing hydroxyalkyl (1a-d), bromoalkyl (1e-h) (diphenylphosphinyl) (1i-k) and carboxyalkyl (2a-d) substituents have been prepared and characterised; the phosphine derivative (1k) has been converted with alkyl iodides (RI; R = Me, Et) into bis-phosphonium) salts (1l and m). During preparation of the diynedioic acid (2a), the non-centrosymmetrical diyne, HO₂CCH₂C=C - C=C(CH₂)₂OH (3), was also isolated. ⁶⁰Co ?-Irradiation of diacetylene monomers (2a-d) and 10,12-tricosadiyn-1-oic acid gave the corresponding polydiacetylene derivatives (4a-d and 5), respectively. Rubidium salts of (4c) and (4d), a barium salt of (4c), and a potassium salt of (5) were prepared and isolated; soluble potassium salts of the carboxylic acid polymers (4) were generated in aqueous solution. The effects of changes in pH on the UV/visible absorption spectra of aqueous solutions of selected carboxylic acid polydiacetylenes have been recorded, and are discussed.