7 to 8.6 kcal mol-1 atom-1 in favor of the looped polyyne, in agreement with previous studies [55, 56]. Moreover, beyond minimization, when nominal temperature

was added to the ring structures, the cumulene rings transitioned to a triple-single bond pattern, potentially due to the strain associated with the imposed curvature, which can facilitate the transition [57]. As the focus here is variation in temperature, only the polyyne configuration is stable throughout the range of temperatures used. Thus, all carbyne ring structures considered are reflective of polyyne structures. Initial three-loop systems are constructed with www.selleckchem.com/products/gsk2126458.html 54, 72, 90, 108, 126, 144, 162, and 180 carbon atoms, with associated ideal radii of approximately 4 to 13 Å. The three-loop fold pattern imposed is meant to maintain a near-constant curvature across the total molecular length. Figure 2 Relative molecular stability. Carbyne rings have been proposed

as a transitional form of carbon during the synthesis of fullerenes [60–63]. Other intermediate forms occurring this website with chain self-adhesion may form (e.g., so-called bow tie structures). To assess the stability of the rings during folding/three-loop configuration, the atomistic energy of cumulene rings and example  intermediate’ structures was assessed with n = 20 (top, blue) and n = 36 (bottom, red) carbon atoms. We see that, aside from the fullerenes, the closed-loop ring polyyne carbyne structures are more energetically favorable (lower energy) than the intermediates depicted, suggesting a relative stability for the equilibrium simulations undertaken. In terms of the ring structure, while linear

carbyne chains have been shown to be stable [19, 58], imposing a closed-loop geometry may be energetically unfavorable. To directly assess the stability of looped carbyne here, a linear chain was equilibrated to determine the difference in atomistic energy in comparison with the 54-atom looped structure, resulting in a nominal difference of 0.02 eV atom-1 and suggesting structural stability. For comparison, the energy difference between flat graphene and a fullerene is in the order of 0.2 eV atom-1[59], while the cohesive energy of carbyne has been found to be in the order of 6.99 [56] to 8.19 eV atom-1[50], in close agreement with the value of 7.4 eV atom-1 calculated here at a finite temperature of 300 K. We also wish Interleukin-3 receptor to assess the stability in comparison with other check details non-carbyne molecular configurations. Empirically, similar ring-like structures with as few as 20 carbon atoms have been observed in the synthesis of fullerenes [60], as well as many intermediate bonded chain forms (e.g., so-called bow tie structures or cycloadducts) [60–63]. To explore whether such intermediate forms may be energetically favorable, simple trial structures were equilibrated to assess the potential energy (also depicted in Figure 2), indicating that the looped/ring structure is more favorable than other intermediate forms.