Hydrogen-Terminated Diamond Is a Continuous Molecular Series
Diamond is the archetypal “macrosopic molecule.” However, hydrogen-terminated diamonds and nanometer-sized diamondoid hydrocarbons form a continuous structural series that includes lower diamondoids (<1 nm), higher diamondoids (~1 to 2 nm), nanocrystalline and chemical vapor deposition (CVD) diamonds (~2 nm to µm), and macroscopic diamonds. Larger members of the series have smaller surface-to-volume ratios and correspondingly lower hydrogen-to-carbon (H/C) ratios. Property data exists for all members of this series except the higher diamondoids, and it is in their nanomer-size range that interesting transitions in properties, quantum effects, are likely to be found.

Internal Structure and Stability
Diamondoids, also called diamond molecules, have the same internal carbon framework as diamond. The combination of diamond-like properties and the chemistry of hydrocarbon molecules give higher diamondoids superb characteristics for nanotechnology. Like diamonds, higher diamondoids offer great rigidity and strength and their carbon chemistry gives them the potential for precise construction and assembly via derivatization strategies.

Enlarge Illustration

Diamond carbon clusters less than ~5 nm in size show greater stability than graphitic carbon clusters of comparable size.

A New Class of Materials
Higher diamondoids have desirable properties:

Enlarge Illustration		Multiple nanometer-sized geometries
		Rigidity
		Durability
		Heat resistance
		Multiple attachment points
		Chirality

Additional New Materials Identified
Alkylated higher diamondoids have been isolated in high purity.  In addition, our team has performed primary derivative chemistry of higher diamondoids to successfully test their derivatization feasibility. Our Science magazine paper and patent applications show the isolation and derivatization of dozens of differently shaped diamondoid molecules. Some of these molecules show handedness (chirality) and other complementary structural features. They have been found to readily crystallize, in some cases forming materials with very high melting points. Co-crystallization has also been observed.

Higher diamondoids can also be polymerized to create specialty materials and can be modified to change their electronic and other properties.

	Alkylated Higher Diamondoids
		Expands potential application
		Isolated from Higher Diamondoids feedstocks in high purity
		Numerous structural varieties

	Derivatized Higher Diamondoids
		Synthesized in laboratory
		Mono and multi-functionalized
		Precursors for polymers, pharmaceuticals

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Diamond is a Continuous Molecular Series

Property data exists for all members of this series except the recently discovered higher diamondoids. Enlarge