Molecular assemblers: molecular machines performing chemical synthesis

Area of Science:

• Nanotechnology
• Molecular Engineering
• Chemical Synthesis

Background:

• K. Eric Drexler's 1986 proposal of molecular assemblers, inspired by R. Feynman, envisioned machines building structures via mechanosynthesis with atomic precision.
• These concepts sparked debate, notably a 2003 Chemical & Engineering News cover story questioning the possibility of molecular assemblers.
• Nobel laureate Richard E. Smalley raised critical objections, including the "fat fingers" and "sticky fingers" problems, challenging the feasibility of atomic manipulation.

Purpose of the Study:

• To evaluate the progress of laboratory chemistry in realizing molecular assemblers over the past two decades.
• To assess the validity and impact of Drexler's initial concepts in light of subsequent scientific developments.
• To analyze the fundamental challenges posed by Smalley's objections to atomic-scale manipulation and construction.

Main Methods:

• Review of historical proposals and scientific debates surrounding molecular assemblers.
• Analysis of advancements in nanotechnology and mechanosynthesis relevant to atomic manipulation.
• Assessment of laboratory chemistry's current capabilities in precise molecular positioning and assembly.

Main Results:

• Smalley's "fat fingers" problem highlights the steric hindrance in accommodating manipulators in nanometer-scale reaction spaces.
• The "sticky fingers" problem describes the difficulty in releasing manipulated atoms or molecules precisely due to adhesion.
• Despite significant challenges, laboratory chemistry has made progress, though true molecular assemblers remain a distant goal.

Conclusions:

• While Drexler's visions may be bold, they serve as a crucial catalyst for innovation in molecular nanotechnology.
• The "fat fingers" and "sticky fingers" problems represent fundamental obstacles that current technology is still working to overcome.
• Continued research in advanced chemical synthesis and nanoscale engineering is essential to bridge the gap towards practical molecular assemblers.