Similarly, considering n = 144 at 725 K (for a bending rigidity of D 725K = 24.0 nN-nm2), with curvature KU55933 increases from 0.11 Å-1 to local peaks of 0.3 Å-1, results in local curvature increasing in approximately 7.2 Å to 27.2 Å to develop the determined energy barrier, again in good agreement with Figure 8, Selleckchem ��-Nicotinamide which indicated multiple (but
short spanning) peaks across the molecular length. It is noted that there is an intrinsic relationship between the magnitude of local curvature and necessary length, i.e., a longer length can develop the equivalent energy barrier with a smaller curvature as U b ∝ Lк 2. Conclusions The results confirm that, while global unfolding implies an overall reduction in curvature, continuity of the molecular loop results in local increases in curvature, resulting in a small yet finite energy barrier to surpass. For longer loops (with less stored bending strain energy due to a decrease in curvature), a higher temperature (e.g., kinetic energy) is required to induce unfolding. In contrast, short loops (with high bending energies) unfold at relatively low temperatures. Using carbyne as a platform, the potential for folding can serve to extend the accessible design space of such materials. It is noted that the heterogeneous/local curvature as depicted in the snapshots in Figure 3,
as well as plotted in Figure 7, was not explicitly considered in check details terms of energy contribution. Rather, the limiting cases – the curvature of the three-loop structure and the curvature of an unfolded ring – were used to estimate the necessary energy. Here, all structures begin in an ideal
configuration, and the deviations from the ideal curvatures are due to thermal fluctuations; the thermal energy (essentially molecular kinetic energy) must impose overcurvature to trigger the unfolding process. Since the heterogeneous curvatures are stochastic (the results plotted are only representative), temperature is used as a proxy to evaluate the necessary energy to unfold. It behooves us to note that the Ureohydrolase looped carbyne structure modeled herein is not attainable experimentally and is intended as an ideal model platform to explore the unfolding phenomena. A similar idealized bead-spring-type’ model could have been constructed but would be subject to the arbitrariness of parameterization. Carbyne provides a compromise – an ideal structure with physical, fundamental, and proven molecular-scale parameterization/behavior through the ReaxFF potential. It is the simplest case from a molecular perspective (a non-reactive homogeneous chain, no solvent, etc.) and is necessary to isolate and observe the thermal contribution to unfolding as well as the local curvature effect. Indeed, understanding the stability and mechanics of folded carbyne loops can be of use in modifying transport properties or triggering mechanisms in active molecular systems.