structure, there is a matching increase in the average unit cell volume. It is clear that
in recent years this increase is being driven by metal-organic structures, as the
average number of atoms per structure for organic structures shows little change
since the beginning of the twenty-first century. Interestingly, the average density has
not increased and has been steady at an average of 1.55 g/cm
3 , varying only by 0.02
in the last 10 years.
The ability to solve many of these bigger structures can largely be attributed to the
improvements in modern crystallographic software, methods and instrumentation as
outlined in the earlier sections. Central facilities are playing an increasing role in the
structures that are added to the CSD, as can be seen from the growth of synchrotron
structures in Fig. 4. While the percentage of the whole CSD from neutron studies is
decreasing, the number of structures added each year is increasing, particularly in the
last 5 years. The CSD also contains a small number of electron diffraction studies,
and this number may increase as the technique develops in the future. Current work
is underway to investigate the output from individual synchrotron facilities and will
be discussed in a separate publication. This work has however highlighted that the
current mechanisms for connecting information concerning the recording of data
collection at central facilities and its subsequent publication could be improved and
that the provenance of the facility used is not well captured as part of the crystallographic result.
As the range of structures solved by crystallography has diversified and evolved,
so too has the range of space groups in which they crystallise. Over half of the
structures in the CSD are monoclinic, which is due to the high numbers of structures
in P2 1 /c, as well as C2/c and P2 1 (see Fig. 5). Over a quarter of structures are solved
in triclinic space groups, predominantly from P-1. A growth in P-1 structures has
Fig. 4 Trends in the percentage of synchrotron (blue) and neutron (yellow) structures added to the
CSD per year
Leading Edge Chemical Crystallography Service Provision and Its Impact on. . .
107
in recent years this increase is being driven by metal-organic structures, as the
average number of atoms per structure for organic structures shows little change
since the beginning of the twenty-first century. Interestingly, the average density has
not increased and has been steady at an average of 1.55 g/cm
3 , varying only by 0.02
in the last 10 years.
The ability to solve many of these bigger structures can largely be attributed to the
improvements in modern crystallographic software, methods and instrumentation as
outlined in the earlier sections. Central facilities are playing an increasing role in the
structures that are added to the CSD, as can be seen from the growth of synchrotron
structures in Fig. 4. While the percentage of the whole CSD from neutron studies is
decreasing, the number of structures added each year is increasing, particularly in the
last 5 years. The CSD also contains a small number of electron diffraction studies,
and this number may increase as the technique develops in the future. Current work
is underway to investigate the output from individual synchrotron facilities and will
be discussed in a separate publication. This work has however highlighted that the
current mechanisms for connecting information concerning the recording of data
collection at central facilities and its subsequent publication could be improved and
that the provenance of the facility used is not well captured as part of the crystallographic result.
As the range of structures solved by crystallography has diversified and evolved,
so too has the range of space groups in which they crystallise. Over half of the
structures in the CSD are monoclinic, which is due to the high numbers of structures
in P2 1 /c, as well as C2/c and P2 1 (see Fig. 5). Over a quarter of structures are solved
in triclinic space groups, predominantly from P-1. A growth in P-1 structures has
Fig. 4 Trends in the percentage of synchrotron (blue) and neutron (yellow) structures added to the
CSD per year
Leading Edge Chemical Crystallography Service Provision and Its Impact on. . .
107