Synthesis and Aggregation Behavior of Poly(arylene alkenylene)s and Poly(arylene alkylene)s Having Dialkoxyphenylene and Aromatic Diimide Groups

Polycondensation reactions of 2,5-dialkoxy-1,4-diiodobenzene with <i>N,N</i>′-ω-dialkenylpyromellitic diimide and <i>N,N</i>′-ω-dialkenyl naphthalenetetracarboxylic diimide in the presence of a Pd­(OAc)<sub>2</sub>–NaOAc catalyst produce six polymers containing the two aromatic groups connected alternatingly by alkenylene spacers. <sup>1</sup>H NMR spectrum of a polymer prepared from 2,5-bis­(dodecyloxy)-1,4-diiodobenzene and <i>N,N</i>′-(10-undecenyl)­pyromellitic diimide (poly­(<b>1a</b>-<b>IA</b>)) indicates that the polymerization involves 2,1- and 1,2-insertion of a vinyl group into the Pd–Ar bond in 70:30 selectivity. Matrix-assisted laser deportion/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) spectra of poly­(<b>1a</b>-<b>IA</b>) and a polymer from 2,5-bis­(dodecyloxy)-1,4-diiodobenzene with <i>N,N</i>′-dialkenyl naphthalenetetracarboxylic diimide (poly­(<b>1a</b>-<b>IIA</b>)) contained a series of polymer fragments with <i>M</i><sub>n</sub> up to 4500. Measurement of electrospray ionization MS (ESI-MS) of the polymers revealed formation of cyclic molecules for 1:1 and 2:2 oligomers. Hydrogenations of poly­(<b>1a</b>-<b>IA</b>) by using [Ir­(cod)­(py)­(PCy<sub>3</sub>)]<sup>+</sup>PF<sub>6</sub><sup>–</sup> (cod = 1,5-cycloctadiene; PCy<sub>3</sub> = tricyclohexylphosphine) catalyst and of poly­(<b>1a</b>-<b>IIA</b>) by a mixture of <i>p</i>-toluenesulfonyl hydrazide (TSH) and tripropylamine (TPA) produce the poly­(arylene alkylene)­s with saturated spacers in 93% degree of hydrogenation. The absorption spectrum of poly­(<b>1a</b>-<b>IA</b>) in CHCl<sub>3</sub> shows an absorption edge at 410 nm, which is at a longer wavelength than that of a mixture of the monomers (370 nm). Light-scattering measurement of the solution (1.00 mmol L<sup>–1</sup>) indicates the presence of aggregates with a hydrodynamic radius of 48 nm. The polymers exhibit weak elasticity at room temperature, as determined by dynamic viscoelasticity analysis (DMA), and it becomes negligible on heating to 75–80 °C (polymer with pyromellitic diimide groups) and 110–122 °C (polymer with naphthalenetetracarboxylic diimide groups). The above properties of the polymers are attributed to attractive interaction between the electron-rich alkoxyphenylene and the electron-deficient aromatic diimide groups both in solution and in the solid state.