Design of Star-Shaped Organoiron Oligomers with Azo Dye Bridges

A series of star-shaped macromolecules bearing distinct symmetrical branches with alternating organoiron complexes and azobenzene moieties were synthesized using both convergent and divergent approaches. The various azo dye and organoiron-containing branches were reacted with multifunctional cores via metal-mediated nucleophilic aromatic substitution and ester condensation reactions to afford multi-substituted three- and four-arm star-shaped oligomers. UV-vis spectral studies of complexes 15 and 22 (lambda (max) = 435 and 427 nm, respectively) show bathochromic shifts (lambda (max) = 576 and 558, respectively) at various HCl concentrations indicating their use as potential acid sensors. Cyclic voltammetric studies of the octa-iron oligomer 22 were reversibly reduced at E (1/2) = -1.53 V.