Conformational polymorphism occurs when a compound crystallises in two polymorphs differing only in the relative orientations of flexible groups (e.g. Ritonavir). At the Beilstein conference, Ian Bruno mentioned another type;  tautomeric polymorphism, where a compound can crystallise in two forms differing in the position of acidic protons. Here I explore three such examples.

Derek Lowe highlights a recent article postulating CH⋅⋅⋅π interactions in proteins. Here I report a quick check using the small molecule crystal structure database (CSD).

The title here is taken from a presentation made by Ian Bruno from CCDC at the recent conference on Open Science. It also addresses the theme here of the issues that might arise in assigning identifiers for any given molecule.

As the Internet and its Web-components age, so early pages start to decay as technology moves on. A few posts ago, I talked about the maintenance of a relatively simple page first hosted some 21 years ago.

It is a sign of the times that one travels to a conference well-connected. By which I mean email is on a constant drip-feed, with venue organisers ensuring each delegate receives their WiFi password even before their room key.

This is taking place in the idyllic surroundings of the Niederwald forest, Rüdesheim, Germany. Here I highlight only aspects of the first three talks.

Mention carbon dioxide (CO2) to most chemists and its properties as a metal ligand are not the first aspect that springs to mind. Here thought I might take a look at how it might act as such.

Research data (and its management) is rapidly emerging as a focal point for the development of research dissemination practices.

Following on from my re-investigation of close hydrogen bonding contacts to the π-face of alkenes, here now is an updated scan for H-bonds to alkynes.

Back in the early 1990s, we first discovered the delights of searching crystal structures for unusual bonding features. One of the first cases was a search for hydrogen bonds formed to the π-faces of alkenes and alkynes. In those days the CSD database of crystal structures was a lot smaller (<80,000 structures;

Layer stacking in structures such as graphite is well-studied.