Linear Alkane Polymerization on a Gold Surface

Abstract

In contrast to the many methods of selectively coupling olefins, few protocols catenate saturated hydrocarbons in a predictable manner. We report here the highly selective carbon-hydrogen (C-H) activation and subsequent dehydrogenative C-C coupling reaction of long-chain (>C(20)) linear alkanes on an anisotropic gold(110) surface, which undergoes an appropriate reconstruction by adsorption of the molecules and subsequent mild annealing, resulting in nanometer-sized channels (1.22 nanometers in width). Owing to the orientational constraint of the reactant molecules in these one-dimensional channels, the reaction takes place exclusively at specific sites (terminal CH(3) or penultimate CH(2) groups) in the chains at intermediate temperatures (420 to 470 kelvin) and selects for aliphatic over aromatic C-H activation.

Homo-coupling of terminal alkynes on a noble metal surface

“…1a. The generated hydrogen atoms are expected to recombinatively desorb as H 2 into the vacuum environment, following the previously established routes 20,29,30 . From the experimental fact that self-assembly of integral molecules readily occurs at low temperatures (cf.…”

“…The surface confinement can moreover promote unique reaction pathways. These have been nicely exemplified by cyclodehydrogenation processes on Cu(111) for tailored nanographenes 19 , or site-specific linear alkane polymerization on an Au(110) facet 20 . A recent related report reveals the prominent role of a noble metal substrate in the catalytic course of a C À C Sonogashira coupling reaction elucidating its heterogenic nature 21 .…”

Controllable Scission and Seamless Stitching of Metal–Organic Clusters by STM Manipulation

“…In this report, the controllable scission and seamless stitching of metal-organic clusters have been successfully achieved through STM manipulations.T he system presented here includes two sorts of hierarchical interactions where coordination bonds hold the metal-organic elementary motifs while hydrogen bonds among elementary motifs are directly involved in bond breakage and re-formation. The key to making this reversible switching successful is the hydrogen bonding,w hichi sc omparatively facile to be broken for controllable scission, and, on the other hand, the directional characteristic of hydrogen bonding makes precise stitching feasible.The direct identification of intermolecular interactions and the delicate tailoring of structural motifs with molecular precision on solid surfaces have recently attracted considerable interest because of the prospect for artificial design of functional molecular nanostructures and nanodevices.S canning tunneling microscopy (STM), especially under ultrahigh vacuum (UHV) conditions,h as proven to be ap owerful method for the precise manipulation of single molecules to trigger various single-molecule behaviors,s uch as translation, [1][2][3] rotation, [3][4][5][6][7][8][9] flipping, [10] cis-trans isomerization, [11][12][13] tautomerization, [14][15][16] dehydrogenation, [17][18][19] and dehalogenation.[20] Not limited to single molecules,S TM manipulations have also been extended to larger molecular structural motifs with great progress in the following aspects:1 )moving clusters, [21] chains, [22][23][24][25] and patches; [26] 2) dissociating dimers, clusters,a nd complexes by breaking hydrogen bonds, [27] coordination bonds, [28][29][30] and carbon-metal bonds, [31] respectively;3)constructing structural motifs by forming new bonds ranging from hydrogen bonds, …”

On‐Surface Formation of Cumulene by Dehalogenative Homocoupling of Alkenyl gem‐Dibromides

“…[1][2][3][4][5][6] In general, most of the on-surface reactions follow pathways different from their counterparts in solution because of the effects of the surface: the reactions are confined in two dimensions and the possible catalytic surface activity. [7][8][9][10][11][12][13][14] Consequently, unexpected reactions have been surprisingly discovered in on-surface synthesis experiments, [15][16][17][18][19][20][21][22] and thus, this strategy has opened up a way for the fabrication of a plethora of novel surface nanostructures which may be hardly obtained by traditional solution methods. Among others, the atomically precise synthesis of carbon nanostructures such as graphene nanoribbons [23][24][25][26][27][28][29][30] and other hydrocarbons like alkanes, dienes and diynes has become a hot topic within the field of onsurface synthesis.…”