0.
Introduction. Welcome
to the world of Crystallography
Why
water boils at 100ºC
and methane at -161ºC; why blood is red and grass is green;
why
diamond is hard and wax is soft; why graphite writes on paper and silk
is strong; why glaciers flow and iron gets hard
when you hammer it; how muscles contract; how sunlight makes plants
grow and how living organisms have been able to evolve into ever more
complex forms…? The answers to all these problems have come
from structural analysis.
Max
Perutz, July
1996 (Churchill College, Cambridge)
With the words pronounced
by the Nobel laureate Max
Perutz we open these
pages (*),
a continuing work in progress, intended to guide the interested
reader into the fascinating world of Crystallography, which
forms part of the scientific knowledge developed by many scientists
over many years. This
allows us to explain what crystals are, what molecules, hormones,
nucleic acids, enzymes, and proteins are, along with their properties
and how can we understand their function in a chemical
reaction, in a test tube, or inside a living being.
The discovery of X-rays in
the late 19th century completely transformed
the old field of Crystallography, which previously studied the
morphology of minerals.
The interaction of X-rays with crystals, discovered in the early 20th
century, showed us that X-rays are
electromagnetic waves with a wavelength of
about 10 -10 meters and that the internal
structure of crystals was regular, arranged in
three-dimensional networks, with separations of that order. Since then,
Crystallography has become a basic
discipline of many branches of Science and particularly of Physics,
Chemistry of condensed matter, Biology and
Biomedicine.
Structural knowledge
obtained by Crystallography allows us to produce
materials with predesigned properties, from catalyst for a chemical
reaction of industrial interest, up to toothpaste, vitro ceramic
plates, extremely hard materials for surgery use, or certain aircraft
components, just to give some examples of small, or medium sized atomic
or molecular materials.
Moreover, as biomolecules
are the machines of life, like mechanical machines with moving parts,
they modify their structure in the course of performing their
respective tasks. It would also be extremely illuminating to follow
these modifications and see the motion of the moving parts in a movie.
To make a film of a moving object, it is necessary to take many
snapshots. Faster movement requires a shorter exposure time and a
greater number of snapshots to avoid blurring the pictures. This is
where the ultrashort duration of the FEL (free electron
laser) pulses will
ensure sharp, non-blurred pictures of very fast processes (European XFEL or CXFEL).
We may suggest you to start getting
an overview about
Crystallography, or
looking at some
interesting video clips collected by the International Union of
Crystallography. Some
of them can directly be reached through
the following links:
In any case, we suggest you to get a previous overview
about the meaning of
Crystallography, and if
you maintain your
interest go deeper into the remaining
pages that are shown in the menu on the left (if you don't see the left
menu, click
here). If you wish to
maintain this navigation mode (without the menu on the left)
just use the small
square logo in the upper
right corner of each page, that always links to
the Table
of Contents, . Enjoy it!
(*)
We try to maintain and expand the content of these web pages,
offering hem to the interested reader, but obviously we are
not
immune to errors,
inconsistencies or omissions. We
are therefore very grateful to several readers who have helped us to
correct some
previously undetected small errors or that have improved the
wording of certain parts of the text. For
anything that needs further attention, please, let us know through Martín
Martínez
Ripoll.
These pages were announced
by the International Union of Crystallography (IUCr),
have been selected as one
of the educational web sites and resources of interest to learn
crystallography, offered
as such in the commemorative
web for the International Year of Crystallography, and
suggested as the
educational website in the
brochure prepared by UNESCO
for the crystal
growing competition for Associated Schools (even in subsequent calls of
this competition.
The Cambridge Crystallographic Data Centre also offers this website
through its Database of Educational Crystallographic Online Resources (DECOR).
Martín
Martínez
Ripoll (1946- ) and
Félix
Hernández Cano
(1941-2005+)
were coauthors of a first version of these pages in the early 1990's.
Later, in 2002 they produced a PowerPoint presentation dedicated to
draw
students' attention
to the enigmatic beauty of the crystallographic world... This file,
called
XTAL RUNNER (totally virus free, although in Spanish) can be obtained
through this link. If
you understand Spanish we also offer
you
the
possibility of reading a short general article of these authors
published in 2003, entitled Cristalografía:
Transgrediendo los Límites. Today we ask
ourselves, where
are those glory days gone?
Some
relevant hints:
- This website is designed by combining three visible areas
in the same window: a header and a menu on the left (which in the
"full-screen mode" always
remain visible), and a central area with the information obtained. This
is what we can call full-screen mode, suitable
for desktop computers and tablets.
- However, the "full-screen mode" may not be suitable for
mobiles, in
which case we suggest using the central-screen
mode, that is, the mode using the central area only,
and starting the session with the Table of Contents.
- In both modes, a small
square logo appears in the upper
right corner of the central screen, which links to
the Table
of Contents.
- All the links that appear in the menu on the left (in full
screen mode), or in the Table of Contents (in any of the modes) lead to
internal pages that are always displayed on the same window.
The
remaining links, which necessarily refer to external pages, will always
be displayed in a "new window". Going back to a previous page can be
achieved using the "Back
" link in the top left of the
header (full screen mode), or through the browser's own
strategy.
- From time to time
we
incorporate some novelties or small corrections into these
pages,
so occasionally we recommended to reload
these pages in
your
browser, or to clear the navigator caché. This
will avoid to see the previously existing pages stored on
your computer's caché.
- Some
companies offer documents directly extracted from these web pages
and you have to pay for them. Please, do
not
participate
in this
fraud! All the material here
presented is freely available to you, although for your
personal
use only, as it is shown below under the copyright
condition.
"Crystallography-Cristalografia",
by Martín
Martínez-Ripoll (Department
of
Crystallografy & Structural Biology), is protected
under a Creative Commons
Attribution + NonComercial 4.0 International License0