All the Ways To Have Substituted Nanothreads

Abstract

We describe a general, symmetry-conditioned way of enumerating isomers of saturated singly substituted one-dimensional nanothreads of the (CH)E and (CH)CR type, where E is a heteroatom and R is a substituent. Four nanothreads - so-called tube (3,0), polytwistane, the zipper polymer, and polymer I, are treated in detail. The methodology, combining symmetry arguments and computer-based enumeration, is generally applicable to isomerism problems in polymers.

Synthesis of double core chromophore-functionalized nanothreads by compressing azobenzene in a diamond anvil cell

“…In spite of this evidence, we do not have a clue of the nanothread structure. In the attempt of bridging such a gap, we considered the four polymeric structures recognized so far as the most favorable: 15,55 tube (3,0), polymer I, polytwistane and zipper. Among these four structures, we can immediately rule out the polytwistane since the formation of this 1D helical structure along the stack direction would require a relative rotation of the neighbouring molecules, thereby becoming incompatible with the formation of double core nanothreads and the preservation of the azo groups.…”

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers and Activation Volumes

“…Three characteristic structures of such threads, based on [4+2] cycloaddition pathways, were proposed (Figure 1 shows them in idealized form, not optimized in geometry). In contrast to the complex structural variety of benzene or pyridine nanothreads, as shown in previous enumerations, 14,15 furan and thiophene nanothreads have less structural variety. This is due to the smaller 5-membered rings, which contain only two double bonds per ring available for polymerization.…”

Towards custom built double core carbon nanothreads using stilbene and pseudo-stilbene type systems

“…As a final step of our analysis we optimized the structure and computed, using density functional theory (DFT), the energy and the IR spectra of the nanothread composed of six molecular units. Among the four polymeric structures identified as the most probable, tube (3,0), polymer I, polytwistane and zipper, 28,58 we can rule out the last two because they are incompatible with the formation of double nanothreads as extensively discussed in the azobenzene case. 35 The Gibbs energy obtained for TS and TS–TA oligomers (S4) after subtracting the electronic contribution and that, of a vibrational nature, related to the different number of hydrogen atoms required to saturate the chain terminations (six more H in the tube (3,0) with respect to polymer I), is lower for the polymer I structure both for TS (0.58 eV) and TS–TA 1 : 1 oligomers (2.54 eV).…”