Japanese Researchers Find Longer Molecules Move Faster Through Nanogates

Researchers in Japan discovered that longer linear alkane molecules pass through dynamic nanoscale pores faster than shorter ones ^[1].

This finding challenges traditional assumptions about molecular transport, suggesting that the flexibility of a pore can fundamentally change how substances are filtered at the atomic level. Such a discovery could influence the development of more efficient membranes for water purification or pharmaceutical delivery.

The study was led by Professor Shuichi Hiraoka of the University of Tokyo and Professor Masanori Tachikawa of Yokohama City University ^[1]. The team conducted experiments using self-assembled molecular nanocubes in water ^[2]. These nanocubes act as gates that can fluctuate, allowing molecules to enter and exit based on specific physical properties ^[3].

Typically, smaller molecules are expected to move through narrow openings more easily than larger ones. However, the research team found that the dynamic fluctuations of these nanoscale pore gates favor the transport of longer linear alkanes ^[3]. This phenomenon is governed by the interaction between the molecules and the transient surfaces of the pores ^[1].

The researchers identified that the surface interactions within the flexible pores create a mechanism that accelerates the passage of longer chains ^[3]. Because the gates are not rigid, they respond to the presence of the molecules in a way that facilitates faster movement for the larger alkanes, a behavior not seen in static pores ^[2].

This discovery highlights the role of "gate dynamics" in molecular sieving ^[1]. By manipulating the flexibility and surface chemistry of these nanogates, scientists may be able to create highly selective filters that prioritize specific molecular lengths regardless of their overall size ^[3].