Poly(diiododiacetylene): Preparation, Isolation, and Full Characterization of a Very Simple Poly(diacetylene)

Abstract

Poly(diiodiacetylene), or PIDA, is a conjugated polymer containing the poly(diacetylene) (PDA) backbone but with only iodine atom substituents. The monomer diiodobutadiyne (1) can be aligned in the solid state with bis(nitrile) oxalamide hosts by hydrogen bonds between oxalamide groups and weak Lewis acid-base interactions (halogen bonds) between nitriles and iodoalkynes. The resulting cocrystals start out pale blue but turn shiny and copper-colored as the polymerization progresses. The development of a crystallization methodology that greatly improves the yield of PIDA to about 50% now allows the full characterization of the polymer by X-ray diffraction, solid-state (13)C MAS NMR, Raman, and electron absorption spectroscopy. Comparison of a series of hosts reveals an odd-even effect in the topochemical polymerization, based on the alkyl chain length of the host. In the cocrystals formed with bis(pentanenitrile) oxalamide (4) and bis(heptanenitrile) oxalamide (6), the host/guest ratio is 1:2 and the monomer polymerizes spontaneously at room temperature, while in the case of bis(butanenitrile) oxalamide (3) and bis(hexanenitrile) oxalamide (5), where the host and guest form cocrystals in a 1:1 ratio, the polymerization is disfavored and does not go to completion. The topochemical polymerization can also be observed in water suspensions of micrometer-sized 6.1 cocrystals; the size distribution of these microcrystals, and the resulting polymer chains, can be controlled by sonication. Completely polymerized PIDA cocrystals show a highly resolved vibronic progression in their UV/vis absorption spectra. Extensive rinsing of the crystals in organic solvents such as methanol, THF, and chloroform separates the polymer from the soluble host. Once isolated, PIDA forms blue suspensions in a variety of solvents. The UV/vis absorption spectra of these suspensions match the cocrystal spectrum, without the vibronic resolution. However, they also include a new longer-wavelength absorption peak, associated with aggregation of the polymer chains.

Induction and control of supramolecular chirality by light in self-assembled helical nanostructures

“…The sample obtained by spin coating of the ultravioletirradiated solution on glass showed clearly discernable peaks at 1,492 and 2,113 cm À 1 corresponding to n(C ¼ C) and n(CC), respectively, of the conjugated DA polymer, indicating successful polymerization of DA (Fig. 5a) 42,43 . The broad background peak was attributed to the inherent fluorescence from the TPA moiety 44,45 .…”

An Iterative Method for the Synthesis of Symmetric Polyynes

“…Diiodobutadiyne ( 2a ), diiodohexatriyne ( 3a ), and diiodooctatetrayne ( 4a ) were each prepared from the corresponding trimethylsilyl‐capped polyynes (that is, 2c , 3c , and 4c , respectively) according to previously described methods 19b,21. 2,4‐Hexadiyne‐1,6‐diol ( 9 ) and 1,6‐dibromo‐2,4‐hexadiyne ( 10 ) were also prepared using previously reported methods 15b,15c…”

Isomorphous Crystals from Diynes and Bromodiynes Involved in Hydrogen and Halogen Bonds

“…The diyne systems are parallel as requested; nevertheless, the angle of the reactive carbons and mostly their distance separations are not favorable, being distorted and much too long, respectively (Figure 4). Topochemical polymerization of diacetylene is also prevented because there is no long range parallel stacking of diynes [58][59][60][61][62][63][64][65][66][67]. …”