HAW-TYNG HUANGZhu, LiLiZhuWard, Matthew D.Matthew D.WardWang, TaoTaoWangChen, BoBoChenChaloux, Brian L.Brian L.ChalouxWang, QianqianQianqianWangBiswas, AraniAraniBiswasGray, Jennifer L.Jennifer L.GrayKuei, BrookeBrookeKueiCody, George D.George D.CodyEpshteyn, AlbertAlbertEpshteynCrespi, Vincent H.Vincent H.CrespiBadding, John V.John V.BaddingStrobel, Timothy A.Timothy A.Strobel2024-09-182024-09-182020https://www.scopus.com/record/display.uri?eid=&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/721227Relative to the rich library of small-molecule organics, few examples of ordered extended (i.e., nonmolecular) hydrocarbon networks are known. In particular, sp3 bonded, diamond-like materials represent appealing targets because of their desirable mechanical, thermal, and optical properties. While many covalent organic frameworks (COFs) - extended, covalently bonded, and porous structures - have been realized through molecular architecture with exceptional control, the design and synthesis of dense, covalent extended solids has been a longstanding challenge. Here we report the preparation of a sp3-bonded, low-dimensional hydrocarbon synthesized via high-pressure, solid-state diradical polymerization of cubane (C8H8), which is a saturated, but immensely strained, cage-like molecule. Experimental measurements show that the obtained product is crystalline with three-dimensional order that appears to largely preserve the basic structural topology of the cubane molecular precursor and exhibits high hardness (comparable to fused quartz) and thermal stability up to 300 °C. Among the plausible theoretical candidate structures, one-dimensional carbon scaffolds comprising six- and four-membered rings that pack within a pseudosquare lattice provide the best agreement with experimental data. These diamond-like molecular rods with extraordinarily small thickness are among the smallest members in the carbon nanothread family, and calculations indicate one of the stiffest one-dimensional systems known. These results present opportunities for the synthesis of purely sp3-bonded extended solids formed through the strain release of saturated molecules, as opposed to only unsaturated precursors. ©journal article10.1021/jacs.9b123522-s2.0-85094219606