Hydrogen-bonded clusters of ferrocenecarboxylic acid on Au(111)

Abstract

Self-assembled monolayers of ferrocenecarboxylic acid (FcCOOH) contain two fundamental units, both stabilized by intermolecular hydrogen bonding: dimers and cyclic five-membered catemers. At surface coverages below a full monolayer, however, there is a significantly more varied structure that includes double-row clusters containing two to twelve FcCOOH molecules. Statistical analysis shows a distribution of cluster sizes that is sharply peaked compared to a binomial distribution. This rules out simple nucleation-and-growth mechanisms of cluster formation, and strongly suggests that clusters are formed in solution and collapse into rows when deposited on the Au(111) surface.

Hydrogen-bonded clusters of 1, 1′-ferrocenedicarboxylic acid on Au(111) are initially formed in solution

“…25 At lower coverage, FcCOOH forms isolated cyclic pentamers, as well as paired-row clusters containing 4-12 molecules. 26 The distribution of cluster sizes is highly peaked, more so than is consistent with a binomial distribution. These statistics are difficult to explain as the result of cluster formation and growth on the surface, and we suggested that molecular clusters instead were forming in solution and depositing intact.…”

“…The self-assembly behavior of pulse deposited Fc(COOH) 2 in methanol is quite different from that observed in pulsed deposited FcCOOH in benzene. 26 The most surprising difference between these two studies was the absence of cyclic pentamers on the diacid surface, which was fully expected to be observed based on the results from the monoacid assembly, and the preponderance of chiral hexamers on the diacid surface which was not observed for FcCOOH. Methanol was used in place of benzene in the current experiment due to solubility concerns, so the differences in the structures observed between the two studies can easily result from the switch from a nonpolar solvent, benzene, to a polar solvent, methanol.…”

Non-intuitive clustering of 9,10-phenanthrenequinone on Au(111)

“…Pulse deposition usually results in a heterogeneous surface, most likely due to the fact that any cluster formation that occurs in the rapidly evaporating droplet will proceed under non-equilibrium conditions and thus can produce kinetic intermediates [ 13 – 14 19 , 27 – 30 ]. For 9,10-phenanthrenequinone we observe three broad categories of assembly: disordered molecules, rectangular tetramers, and ordered linear rows, as seen in Fig.…”

“…Some hydrogen-bonding organic molecules have a common feature in that C–H···O bonding plays a critical role in stabilizing metastable clusters [ 13 – 14 19 – 20 ]. This makes 9,10-phenanthrenequinone ( Fig.…”

Editorial: Bioenergy and biorefinery – biological solution for sustainable development of human society

“…In a recent study by Kandel research group 27, they have demonstrated that Fc molecules form a self‐conjugated assembly with five‐fold symmetry that is the only quasicrystalline material with such a five‐fold symmetry. The same research group has shown that Fc quasicrystals are formed initially in a solution phase and then adsorbed onto the surface 28. The pentamer structures of the Fc quasicrystals are stabilized by formation of H‐bonds among the carboxylic acid functional groups of Fc molecules.…”