Chemical Nanotechnology: From Molecules to Applications

Abstract

The article reviews the potential of bottom-up chemical methodologies in synthesizing nanoscopic materials, and evaluates the influence of chemistry involved in materials processing on functional and structural properties of ceramics. Application of molecular sources in preparation of nanomaterials allows an intrinsic chemical encodingl in the initial stages of molecule-to-material transformation which plays an important role in tuning the properties of nanomaterials. Salient examples describing the precursor- structure-property-application relationship have been discussed to support the above arguments.

Nano-Structured Ceramics by Gas-Phase Reaction

“…The diameters do not appear to depend on the temperature or reaction time; however, the fibers will grow longer with increased reaction time. Invariance in nanofiber diameter with temperature and time leads to the conclusion that the nanofiber diameter is controlled by the size of the gold particle catalyzing growth (6,12,13).…”

“…Since the tip of the fiber is only composed of gold and the melting point of gold is not lower than 800 °C for particles 12 nm and larger (19), it is likely that the nanofiber growth is initiated by the gold particle and may continue through the adsorption of molecular species on the low-energy surface of the growing nanofibers. These adsorbed molecules could then diffuse to a low-energy state at the growth front (vapor-solid growth mechanism) (12,22). The TEM results along with the XRD data show that the fiber is rutile SnO 2 with a pure gold tip.…”

“…The ability to modify their electrical, optical, magnetic and chemical properties by varying their cation valence or anion occupancy make functional oxides such as stannic oxide (SnO 2 ) attractive materials for fabrication of smart devices (1). Recently, lowdimensional nanostructures such as nanobelts (2)(3)(4)(5)(6)(7)(8) and nanowires (4,6,(9)(10)(11)(12) of functional oxides have become the focus of intense research due to their fundamental physical properties and their potential for integration into devices such as field effect transistors and sensors (2,6,(12)(13)(14)(15). One of the most common ways to produce large quantities of nanostructures is with vapor phase synthesis.…”

Ligand-Modulated Chemical and Structural Implications in Four-, Five-, and Six-fold Coordinated Aluminum Heteroaryl Alkenolates

“…In the course of our ongoing efforts toward volatile and air-stable compounds as precursors for metal organic chemical vapor deposition (MOCVD), we are investigating the properties of heteroaryl alkenols as chelating ligands for various metals. − These aryl-substituted alkenols (N Ar –CH–C(CF 3 )–OH) (Scheme A ) or aryl enaminones (N Ar H–CH–C(CF 3 )O) (Scheme B ) containing different heterocycles exhibit chemical characteristics comparable to those found in β-diketones. However, the possibility of varying the heteroaryl unit in the alkenol backbone allows to create a rational balance of steric and electronic factors that is essential to design new precursors. ,,, In addition, the incorporation and variation of −CF 3 groups increases the volatility of the compounds by influencing the intermolecular interactions important to control the nuclearity of the molecular compound.…”

“…However, the possibility of varying the heteroaryl unit in the alkenol backbone allows to create a rational balance of steric and electronic factors that is essential to design new precursors. 1,2,13,30 In addition, the incorporation and variation of −CF 3 groups increases the volatility of the compounds by influencing the intermolecular interactions important to control the nuclearity of the molecular compound. Copper complexes of 3,3,3-trifluoro(pyridine-2-yl)propen-2ol were first reported by McGrath and Levine; 31 however, these ligands are only little investigated, 32−37 although an accessible synthesis of various trifluoroacetylazines was reported by Kawase et al 38 We have improved the synthesis of dimethyloxazol-based ligands and extended the concept to a library of heteroaryl alkenolate ligands based on electronic push−pull effects.…”