Chromatic Studies of a Polymerizable Diacetylene Hydrogen Bonding Self-Assembly:  A “Self-Folding” Process To Explain the Chromatic Changes of Polydiacetylenes

Abstract

In the present study, a new diacetylene compound (PDATAZ), which readily forms a complementary hydrogen bonding self-assembly at the air−water interface or in the solid state with barbituric acid (BA) or cyanuric acid (CA), was designed and synthesized. The photopolymerization studies of PDATAZ and its assembly with BA or CA have revealed some important insights on the chromatic properties of polydiacetylenes. It was found that the chromatic property of polydiacetylenes is determined by whether the polymer chain is capable of adopting a linear chainlike shape. With the continuous increase of the length of the polymer chain, the original linear polyenyne backbone starts to “self-fold” to a “zigzag” structure due to the free rotation of single bonds within the polymer chain. The efficient π-electron delocalization along the polyenyne backbone is interrupted by this process, leading to a chromatic change from the blue to red form of polydiacetylenes. If there are strong intermolecular interactions existing between the polar groups of the side chains, such as the complementary hydrogen bonding network between the triaminotriazine (TAZ) moiety of the diacetylene amphiphile and its complementary components, the movement of the side chains is restricted and the folding process of the polymer backbone is inhibited. The polymer backbone is able to maintain its extended chainlike conformation, leading to only the blue form absorption band.

Functional Self-Assembling Bolaamphiphilic Polydiacetylenes as Colorimetric Sensor Scaffolds

“…8 Leblanc et al proposed that extended radiation-induced chromatic changes of PDAs may arise from "selffolding" of the originally linear conjugation backbone into a zigzag structure (via the free rotation of single bonds) upon propagation of the polymer chain, resulting in a shortened π-electron delocalization. 31 In this study, the dramatic morphological transformation of BPDAs from ribbons to nanofibers accompanying the charge-induced CR (Fig. 5) suggest that both side chain disordering and disruption of main chain packing play important roles in the observed chromatic shift.…”

“…7,8 A compromised explanation suggests that the alkyl side chains in the "red phase" remain in an ordered conformation, with only a slightly different packing mode from the "blue phase". 31 More recent investigation of the temperature dependence of visible absorption spectra and the electron diffractions of PDA films revealed that the electronic natures of the PDAs are strongly dependent on their resonance backbone structures as well as the stacking of the main chains. 8 Leblanc et al proposed that extended radiation-induced chromatic changes of PDAs may arise from "selffolding" of the originally linear conjugation backbone into a zigzag structure (via the free rotation of single bonds) upon propagation of the polymer chain, resulting in a shortened π-electron delocalization.…”

Synthesis, Structure, and Nonlinear Optical Properties of Cross‐Conjugated Perphenylated iso‐Polydiacetylenes

“…A superlinear increase in nonlinearities with a distinct change in slope, however, could arise from an increased ordering of the sample in solution, such as folding. [34] This prospect is discussed below.…”

Fluorescent Glyconanoparticles as a Sensitive Device to Monitor Sugar-Involving Molecular Events

“…Since the coloriometric change upon the binding of toxins seems to be caused by the reorientation of lipids and a reduction in the length of the conjugated lipid backbone due to distribution of the polymer network. 10 The reason for the change in fluorescence can be similarly speculated. Therefore, we consider that a reduction in the flexibility of the conjugated lipid backbone after the binding of proteins on the surface of the nanoparticles may lead to a decrease in fluorescence.…”