X-Message-Number: 23715
From: "Aschwin de Wolf" <>
Subject: Step towards building tiny, molecular motors
Date: Mon, 22 Mar 2004 13:51:13 -0500

            Step towards building tiny, molecular motors


      Achieved by Hebrew University, UCLA scientists

      A step towards building tiny motors on the scale of a molecule has
been demonstrated by researchers at the Hebrew University of Jerusalem and
the University of California at Los Angeles (UCLA).

      In an article appearing in the current issue of Science magazine, the
researchers from the two institutions described how they were able - through
light or electrical stimulation - to cause a molecule to rotate on an axis
in a controlled fashion, similar to the action of a motor.

      The consequences of such an achievement could lead to the design of
molecular devices on a "nano" scale (one billionth of a meter), capable of
operating industrial or surgical processes that larger equipment could not

      The researchers who wrote the article for Science are Prof. Roi Baer
of the Institute of Chemistry at the Hebrew University of Jerusalem, along
with his graduate student, Esther Livshits, and Prof. Daniel Neuhauser,
Prof. M. Frederick Hawthorne, Dr. Jeffrey I. Zink, Johnny M. Skelton, Dr.
Michael J. Bayer and Chris Liu of the University of California at Los

      Prof. Baer explained that tiny "machines" already exist in natural
biological systems. For example, certain bacteria are equipped with a small
molecular motor that rotates a flagellum and allows the bacteria to move and
navigate in water. The "fuel:" driving these motors is energy-rich
molecules, abundant in the living cell, that are programmed to release their
stored energy.

      The challenge for scientists is to design man-made molecular motors -
not necessarily confined to living cells -- that can be controlled and
powered using light or electricity. Such man-made motoric actions have been
achieved in the past, but the Hebrew University-UCLA team says it is the
first to achieve motion that can be halted. This is important because in
order for a tiny molecular motor to have any practicality, it must be
capable of being stopped or locked in position. This would enable molecular
devices to be used, for example, as tiny switches or to perform other
mechanical tasks.

      Molecular machines are still a long way down the road, said Prof.
Baer. But it is clear that once such a technology is available, it will be
possible to design new materials and control their properties with extremely
high precision. It will also be possible to manipulate and intervene in the
most delicate processes in the living cell - with at present unimaginable
benefits for medical experimentation and ultimately treatment.

      The molecule used by the researchers was composed of four elements -
boron, carbon, nickel and hydrogen. The nickel was the key to the process,
since it is capable of bonding in several ways in molecules.

      The model developed is composed of two spherical structures with a
common axis. When exposed to light or electrical stimulation, the top sphere
rotates with respect to the bottom one by an angle of 144 degrees. After
this rotation, the molecule is locked into its new position.

      By measuring the absorption, emission and scattering of light from the
molecule and using detailed theoretical calculations, the researchers were
able to study the intricate mechanism of the molecule's operation. They are
now trying to find a way of chemically bonding one of the spheres of the
molecule to a surface and attaching a molecular chain to the other sphere,
capable of performing a rotary task on demand (a kind of mini-motor).
Further, by attaching two molecules together along their axes, say the
scientists, rotations other than 144 degrees could be achieved.

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