Two-Dimensional Solid-State Topochemical Reactions of 10,12-Pentacosadiyn-1-ol Adsorbed on Graphite

Abstract

The photoinduced topochemical reaction of the diacetylene (DA) compound 10,12-pentacosadiyn-1-ol in the two-dimensional (2D) crystal phase adsorbed on graphite was examined by scanning tunneling microscopy (STM). The reaction efficiency and the structure of the generated polydiacetylene depend on its polymorphic forms, i.e., the "herringbone" or the "parallel" monomer arrangements. The reaction efficiency of the herringbone arrangement is lower than that of the parallel arrangement because the distance R between the probable reactant acetylenic carbon atoms of the herringbone arrangement is longer than that of the parallel arrangement. However, the fact that polydiacetylenes form from the herringbone arrangement (R = 0.58 nm) is contrary to the geometric criteria for the polymerization of three-dimensional (3D) crystals (the reaction was only observed if R < 0.4 nm). The polymerization criterion for the 2D phase differs from that of the 3D phase. In addition, the STM cross-section profiles of the polydiacetylenes reveal that the "lifted-up" and "in-plane" conformations form from the parallel and herringbone arrangements, respectively.

Diacetylene polymerization on a bulk insulator surface

“…14,15 The majority of these studies have been carried out using a graphite support. 8,12,13,[16][17][18][19] Only a few other substrates have been studied for diacetylene polymerization, including, e.g., Au(111), 14 MoS 2 (0001), 8,15 hexagonal boron nitride 20 and epitaxial graphene on SiC(0001). 21 Most importantly, no bulk insulator surface has been used so far.…”

Stability of Two-Dimensional Polymorphs for 10,12-Pentacosadyn-1-ol on Graphite Investigated by SPM

“…All the preparation processes were carried out under ambient conditions. The two-dimensional (2D) self-assembly of the PCDYol was obtained by quasi-Langmuir-Blodgett (quasi-LB) method [9,10] or by spin-coating. Sample preparation by quasi-LB method was carried out as follows.…”

“…For these polymorphic forms, the reaction efficiencies of the chain polymerization are remarkably different [10]. In this work, we investigate the thermodynamic stability of the two polymorphs of PCDYol monomolecular films, using scanning tunneling microscopy (STM) and atomic force microscopy (AFM).…”

Organization and structure of mixed Langmuir films composed of polydiacetylene and hemicyanine

“…A similar mechanism to the observed for the 2D photopolymerization of DA adsorbed on graphite is proposed, where the diacetylene units are ordered in a similar way as are placed along the k axis in Scheme 1. 20,21 Table 1for values of cell parameters. 18 Inset in C: geometric criteria for 2D cell parameters.…”