Helical Pore Alignment on Cylindrical Carbon

Abstract

Interest in chiral substances has mainly focused on the substances themselves, but not on the accompanying space, especially regarding the pore alignment. As a method to form both the chiral substance and the accompanying space, cylindrical self‐assembly of uniform polystyrene nanoparticles with fructose is carried out in the presence of both carbon and sodium alginate, which is followed by heat treatment in an inert atmosphere. The carbonization generates fructose‐derived honeycomb‐like carbon walls with helically aligned nanopores left after the polystyrene decomposition. The diffuse reflectance circular dichroism measurements give peaks with opposite signs for the d‐ and l‐fructose‐derived cylindrical carbons. Circularly polarized light sensitivity in transient photoconductivity is confirmed apparently in the carbon‐based helical structures. This sensitivity as well as straightforward formation of composites with another component to give helicity shows potential applications of the helically aligned pores.

Helically aligned fused carbon hollow nanospheres with chiral discrimination ability

“…A new form of helical structure was realized in carbon materials, that is, helically aligned fused CHNSs on MWCNTs, which differed from the previously reported twisted-strandlike [11][12][13] or honeycomb-like porous 14 structures. Helicity was confirmed by VUVCD measurements, and the carbonizing behavior was characterized by TG-DSC-MS measurements to elucidate the generated helicity.…”

“…Studies on helical carbon materials have shown that positive and negative peaks in the CD spectra correspond to LH and RH helical structures, with the peak position modulated by the helical pitch. [12][13][14] The disorder was observed in the helical alignment in the FESEM and TEM images. Therefore, we recorded the CD spectra of the carbon samples obtained in this study to confirm the helicity.…”

“…The CD spectra were recorded in the vacuum-ultraviolet (VUV) region because these helical carbon materials have smaller pores and cylindrical diameters, and consequently, shorter helical pitches than those of previously reported materials exhibiting CD peaks in the visible-light region. 14 Fig. 4a and b show the VUVCD and absorption spectra, respectively, of substrate-a, C-EC-NP-a, C-EC-NP-R-a, and C-EC-NP-S-a.…”

“…[11][12][13] Recently, we synthesized cylindrical carbon with honeycomb-like helically aligned pores by selfassembling 40 nm polystyrene nanoparticles (NPs) as a pore formation template with fructose as a carbon source as well as a chiral inducer. 14 These helical carbon materials exhibited optical activity, as observed by circular dichroism (CD) measurements, but no chirality-based functions were found. No studies have reported interactions between chiral molecules and helical carbon materials, which may be due to size mismatch; for example, alanine 15 and 1,1′-bi-2-naphthol (BINOL) 16 have sub-to one-nanometer sizes, and helical carbon has a diameter of at least ∼100 nm.…”

Tunable and ordered porous carbons with folding-like nanoscale framework via interdigitation and twisting

“…Considerable progress has been made in the strategies to synthesize one dimensional (1D) twisted porous nanostructured materials of silica 18 and chiral nematic carbon films (2D), 6,7 and very recently, helical pore alignment around the 1D carbon fibre has been reported. 19 However, nanostructural knotting or folding-characterized as a selfstabilized ordered system made via interdigitation and twisting (or rotation)-has not been addressed in the field of material synthesis. Sophisticated preparation of molecular building blocks and their mutual coordination has led to chiral covalent organic frameworks (COFs) 20 or interlocked metal organic framework (MOFs) with mechanical flexibility and associated dynamic porous framework alteration behavior.…”