Self-Assembled Two-Dimensional Molecular Host-Guest Architectures From Trimesic Acid

Abstract

The adsorption of 1,3,5-Benzenetricarboxylic (Trimesic) Acid (TMA) to a single crystal graphite surface has been studied under Ultra High Vacuum conditions. This work focuses on inducing a particular self-assembly structure by OMBE (Organic Molecular Beam Epitaxy), characterized by periodic non-dense-packing of the molecules. Two coexisting phases could be imaged with sub-molecular resolution by STM. Induced by directed hydrogen bonding, the organic molecules built in both cases a two-dimensional grid architecture with molecular caves. This two-dimensional host structure can accept single trimesic acid guest molecules in different positions.

Hydrogen and Coordination Bonding Supramolecular Structures of Trimesic Acid on Cu(110)

“…STM Measurements at 130 K. When TMA is deposited onto the Cu(110) surface at 130 K, STM shows triangular protrusions which are assigned to flat-lying TMA molecules. [24][25][26]28,49,51,53 As confirmed by LEED, no long-range structural order is detected (see Figure 2), which is attributed to restricted surface diffusion at low substrate temperatures. Nevertheless, a short-range interaction between neighboring molecules is observed.…”

“…These STM observations suggest that at 130 K, the acid groups of TMA are at least partially intact and that hydrogen bonding is the dominant intermolecular interaction at this temperature. 24,49,51,53 B. IR Measurements. Figure 3 shows a series of infrared (IR) spectra as a function of increasing coverage during TMA deposition on Cu(110) at 85 K. For low coverage (spectra a-c), the main bands are found at 743, 940, 1427, and 1643 cm -1 .…”

“…These have the form of chains running along the [11 h0] direction of the Cu-(110) surface (see Figure 7). The chains consist of alternating bright triangular features (flat-lying TM molecules [24][25][26]28,49,51,53 ) and faint round protrusions associated with Cu adatoms. [24][25][26]28 The apparent height of the TM molecules of 1.40 ( 0.30 Å is nearly double the height of the Cu protrusion of 0.75 ( 0.20 Å when scanning at -1 V and 1 nA.…”

“…34,35 A typical linker molecule used for surface MOCNs is trimesic acid (TMA) comprised of three carboxylic acid groups ordered in a planar triangular arrangement around the central phenyl ring, Figure 1. TMA has been investigated in its acidic form in solids 46,47 as a three-dimensional MOCN coordinated to Cu ions 23, 48 and on low reactivity surfaces, 12,14,[49][50][51][52][53][54][55] where mostly hexagonal honeycomb networks are found, which are formed by intermolecular hydrogen bonding. However, in its deprotonated form, the carboxylate groups may combine with metal atoms to form extended metal-organic coordination networks in three dimensions in the solid state 48,56,47 and on surfaces in two [24][25][26]28 and one dimensions.…”

Molecular Assembly of Rubrene on a Metal/Metal Oxide Nanotemplate

“…Surface nanotemplates are substrates that are artificially or naturally patterned at the nanoscale, where specific functionalities provide surface cues that are able to drive selfassembly. 5 There are several types of surface templates among which the most common are long-range reconstructions, 6-9 step bunching, 10,11 vicinal surfaces, 12 ordered growth from defects, 13,14 inorganic nanomeshes, 15,16 organic porous networks, [17][18][19][20][21][22][23][24][25] metal-organic coordinated networks, 26,27 and macrocycle monolayers. 28 A long range reconstruction that results in an interesting onedimensional nanotemplate is the (2×1) oxygen-induced reconstruction of the Cu(110) surface.…”