Nanoparticles Change the Ordering Pattern of n-Carboxylic Acids into Nanorods on HOPG

Abstract

This paper describes the formation of organic nanorods induced by monolayer-protected inorganic nanoparticles. Alkanes and alkane derivatives, such as n-carboxylic acids, self-assemble on highly oriented pyrolytic graphite (HOPG) into a persistent molecular packing structure that is dictated by the epitaxial interaction between the carbon chain plane and the HOPG basal plane. Carboxylic acids form 2-D crystalline layers consisting of nanostripe domains whose periodicity is one or two times the molecular chain length. However, when the molecular ordering occurs in the vicinity of a nanoparticle, this persistent HOPG-dominated nanostripe pattern is disrupted, and nanorods attached to the nanoparticles become the dominant structure. In order to understand the underlying mechanism of the nanoparticle-mediated nanorod formation, the effects of film-forming conditions, carboxylic acid chain length, nanoparticle size, and chemical composition of the nanoparticle are examined. It is determined that carboxylic acid nanorods can be induced by nanoparticles of different core materials including CdSe, CdS, and Au, as long as the protecting monolayer allows sufficient dispersion and colloidal stability of the nanoparticles in solution. A carboxylic chain length range amenable to the nanorod formation is identified, as is the relationship between the nanoparticle size and the number of nanorods per nanoparticle. This study contributes to the understanding of seed-mediated crystallization and molecular ordering. Moreover, it defines the parameters governing solution-based formation of hybrid nanostructures and nanopatterns incorporating dual functionality as defined by the inorganic nanoparticle and organic nanorod, respectively.

Electrocrystallization of Tetrathiafulvalene Charge-Transfer Salt Nanorods on Gold Nanoparticle Seeds

“…The nanorods of (TTF)Br 0.7 electrochemically grown on GNPs are remarkably similar to carboxylic acid nanorods grown on monolayer-protected nanoparticles by fast solvent evaporation during spin-coating. − The GNP seed size effect can be understood by the classical nucleation theory. The presence of a 2D seed surface lowers the nucleation energy by the nucleation capability factor, f = Δ G c HET /Δ G c = (1/4)(1 – cos θ) 2 (2 + cos θ).…”

“…The method has the potential to deposit small-molecule interconnects using solution chemistry on patterned circuitry. This work represents a significant advance over our original discovery of a seed-mediated mechanism of making n -carboxylic acid nanorods on monolayer-protected nanoparticles of CdSe, CdS, and Au. − The previous work was conducted by coprecipitating the two components from the solution phase on HOPG during spin-coating. This work brings the seed-mediated mechanism a step closer to the actual application by demonstrating the synthesis of conductive TTF charge-transfer salt nanorods using highly controlled electrocrystallization.…”

Electrodeposition of partially oxidized tetracyanoplatinate nanowires on seeds and patterns for gas sensing

“…We discovered a seed-mediated method to nucleate 1-D nanostructures of small-molecule compounds bearing morphological resemblance to those produced by VLS or SLS [17]. In our case, the small size (or highly curved nanoparticle surface) is hypothesized to directly cause the size and shape confinement of the 1-D nanostructures [18,19]. More recently, we applied the seed-mediated mechanism for the electrocrystallization of tetrathiafulvalene (TTF) charge-transfer salt nanowires [20].…”

Bacterial patterning at the three-phase line of contact with microtextured alkanes

“…Initial bacterial interactions with surfaces are a critical step in biofilm formation, hence the aim of this study was to examine the underlying mechanisms that dictate the interaction and structuring of bacterial cells on microtextured C 20 and C 22 surfaces as analogs to the dragonfly epicuticle, achieved through the ability of highly ordered graphite (HOPG) to act as a template due to its homogeneous and highly ordered surface structure (Fox & Zisman 1952;Wang et al 2010).…”