Crystal structure of polydiacethylene TCDU revisited

Abstract

Exciton self-trapping and formation of diradical intermediates in 5,7-dodecadiyne-1,12-diol bis[phenyl carbamate] (TCDU) crystals at low temperaturesThe crystal structure of the as-prepared form ofpoly(S,7-dodecadiyne-l,12-diyl-bisphenylurethane), customarily called TCDU, has been reexamined by an x-ray analysis. Bond lengths of the conjugated polymer backbone chain presently determined indicate that the structure of the as-prepared form of TCDU crystal is more close to that predicted for the acetylenic structure than the hitherto presumed butatrienic one.

Study on microstructure and mechanical properties of polydiacetylene composite biosensors

“…The SAED diffraction is a ring and a hexagonal spot pattern on the edge of the ring, suggesting a monoclinic crystal structure of PDA. A similar monoclinic crystal structure in PDA was previously reported by Tachibana et al and Kobayashi et al 46,47 The masked image shown in Figure 14(c) exhibited an average d-spacing (interplanar spacing between the atomic planes arranged in any crystal structure) for the lattice planes of approximately 2.5Å. Such a small d-spacing revealed a highly packed structure in the PDA, suggesting that the PDA primarily consists of highly packed crystals with great molecular alignment.…”

“…The PCDA molecules were first mixed with the PEO or the PU and dispersed in solvents. A similar monoclinic crystal structure in PDA was previously reported by Tachibana et al and Kobayashi et al 46,47 The masked image shown in Figure 14(c) exhibited an average d-spacing (interplanar spacing between the atomic planes arranged in any crystal structure) for the lattice planes of approximately 2.5Å. During electrospinning, the PCDAs were able to self-assemble due to electrostatic forces.…”

Twisted polydiacetylene quantum wire: Influence of conformation on excitons in polymeric quasi-one-dimensional systems

“…It has also been shown that bond lengths in blue and red PDA do not differ significantly. It was proposed early on that red chains are non planar, successive repeat unit being rotated in opposite directions relative to the chain's average plane [23], so that the 1D unit cell contains two non translationally equivalent repeat units; we believe that this is the most likely explanation despite the fact that several red PDA crystal structures are not reported with a doubled unit cell [24,25]. A possible explanation for this discrepancy has been proposed in [17].…”

Theoretical Investigation on the Bistability of Polydiacetylene

“…But structural difference between the two phases is not well understood, because detailed structures of PDA in both the A and B phases are unknown. In the case of TCDU (R¼-(CH 2 ) 4 OCONHC 6 H 5 ) experimental structures in the B phase are available (Enkelmann and Lando, 1978;Kobayashi et al, 1987). As far as we know there is no other experimentally determined crystal structure of PDA which exhibits thermo-or photochromism.…”

“…An as-grown TCDU crystal with the B phase (TCDU-1 according to Enkelmann (1984)) can be easily converted to the A phase by applying pressure (Kobayashi et al, 1987), and the thermally induced A-B transition is taken place at quite low temperature (Iqbal et al, 1977). TCDU has another crystal form (TCDU-2).…”