Structure of the Month – May 2012

May 012012
 

Presented by: Nicholas G. White
Research Leader: Prof. Paul D. Beer
Published: Chemical Communications

Pyridinium-3,5-bis(triazole) can bind anions through polarised C-H···anion hydrogen bonds.  We have incorporated this motif into pseudorotaxanes, catenanes and rotaxanes (in conjunction with an isophthalamide macrocycle), and the resulting interlocked architectures are formed in high yields and display interesting and unusual anion selectivities.  Despite the difficulties of crystallising such systems, single crystals of a pseudorotaxane, rotaxane and catenane have all been isolated (as chloride salts).  Data were collected using a Nonius Kappa-CCD, synchrotron radiation on I19 at Diamond and Cu Kα radiation with an Oxford Diffraction (Agilent) SuperNova (respectively).  All three datasets are of unusually high quality for such systems (final R1 [I > 2σ(I)] = 6.9-8.0%).

Structure of the Month – May 2012

Structure of the Month – May 2012

Diamond Light Source Annual Review

Jun 032011
 

The 2011 Diamond Annual Review, which highlights some of the world-class research recently undertaken at Diamond Light Source is now available from their website.  The report includes a contribution from Prof. Paul Beer covering some of the fascinating interlocked structures determined from data collected using the Small Molecule Beamline, I19, as part of the Oxford Block Allocation Group (BAG).  Highlights of their work include a novel halogen bonded rotaxane and the first reported crystal structure of a “handcuff catenane”.

Structure of a handcuff catenane

Structure of a handcuff catenane

Structure of the Month – June 2011

Jun 012011
 

Presented by:  Matthew J. Langton, Jonathan D. Matichak & Dr. Amber L. Thompson
Research Leader:  Prof. Harry L. Anderson
Published:  Chemical Science (cover article)

Fully π-conjugated porphyrin oligomers exhibit remarkable properties such as ultrafast energy migration, strong two-photon absorption and wire-like charge transport. The possibility to encapsulate them by rotaxane formation may provide valuable control over their properties by offering a unique approach to engineering intermolecular interactions. An active-template Cu-mediated Glaser coupling provides an efficient route to these structures. Data from crystals of this rotaxane were collected in-house. The porphyrin dimer is slightly twisted and non-linear, contrasting with previously reported structures which possess an inversion centre (and are thus rigorously planar). The phenanthroline units of the threaded macrocycle form tightly packed π-stacks in the crystal.

Structure of the Month - June 2011

Structure of the Month – June 2011

Structure of the Month – September 2010

Sep 012010
 

Presented by:  Dr. Nathan L. Kilah, Matthew D. Wise, Christopher J. Serpell, Nicholas G. White, Dr. Kirsten E. Christensen & Dr. Amber L. Thompson
Research Leader:  Prof. Paul D. Beer
Published:  Journal of the American Chemical Society

This structure represents the first use of solution phase halogen bonding to control and facilitate the anion templated assembly of an interlocked structure.  It  unambiguously confirms the interlocked nature of the system, and the vital role played by halogen bonded anion templation in its assembly.  The crystals were small and diffracted poorly, so data were collected on I19 at Diamond.  Unfortunately, they also suffered severe radiation damage, so data were collected using a single φ scan leading to a paucity of data.  Extensive disorder meant that the final refinement had a data:parameter ratio of 3.6:1 and required 4401 restraints.

Structure of the Month - September 2010

Structure of the Month – September 2010