The type of counter ion is important in determining mechanical properties and could be selected to afford slip and plastic deformation.

Salt formation is used to optimize pharmaceutical properties for carboxylic acid drugs but selection can often be empirical. An extended series of salts of the anti-hyperlipidaemia carboxylic acid drug gemfibrozil was prepared using related series of amine counterions to gain a molecular insight into the impact of crystal packing arrangements on their physicochemical properties. With only a few exceptions, the salts had similar crystal packing motifs. Although there was no discernible relationship between melting point of the salt form and the aqueous solubility of the salt across the whole dataset, there were trends within structurally-related series of salts relating increasing melting enthalpy with increasing molecular weight of the counter ion.3

the home system allows collection of data as soon as the crystals are produced to get the initial solution of novel structures and is invaluable in the quick turnover often required in ligand-binding studies. We will describe how the combination of the updated Agilent Technologies SuperNova, a highly efficient compact diffractometer, with the new version of fully automated CrysAlisPro data collection and processing software, optimized for macromolecular crystallography, makes an ideal home lab solution complementing synchrotron data collection. New unique features of CrysAlisPro and several examples of high quality results obtained with the system will be presented.

Today's most interesting samples rarely make our jobs easy for us. Unfortunately many of the systems that we want to study crystallise as very tiny crystals. This can be particularly true of pharmaceuticals but is a widespread difficulty in many areas of chemistry and materials where we repeatedly face these challenges. Constant pressure to deliver high quality results and extract as much information as possible are coupled with pressures to do so both cost and time efficiently. The combination of the Rigaku MicroMax 007HF generator with the RAPID II unique curved, large area image plate detector already provides a hugely flexible tool to address many of these challenges. Advances in optics now mean that this powerful combination of generator and detector can be used with both Mo and Cu radiation (or Cu and Cr) on the same instrument, just by swapping the rapidly interchangeable targets. The image plate is highly sensitive for all these wavelengths providing for high quality data without compromise. The extremely large active area of the detector (-60 to 144°) allows a massive solid angle of data to be collected in a single exposure; ideal for fast high resolution Cu data for absolute configuration determination and equally for very high resolution data with Mo radiation. The exceptional low noise and wide dynamic range also suit the long exposure times often necessary for very tiny crystals -even with a brilliant source -without saturation or excessive noise problems. This single instrument is so versatile that it can replace several others -for single crystal diffraction studies (both small and macromolecular) at both wavelengths as well as powder diffraction. Results of studies using this new dual wavelength capability system will be presented.Flurbiprofen (F) is a valuable anti-inflammatory drug, but its aqueous solubility is only 0.03 mg mL -1 . Its salts with cyclohexylammonium or adamantylammonium ions still have limited solubility; in both structures N-H…O hydrogen bonds form ladders [1]. In a series of H 2 NC(CH 3 ) 3n (CH 2 OH) n salts of the carboxylic acid drug gemfibrozil [2] the members with n = 0, 1 and 2 also form ladders; but when n = 3, these change to layers [2]. Hoping that counter ions with OH groups would enhance the solubility of F through hydrophilicity and would improve its mechanical properties by greater hydrogen bonding, we have studied the diethanolamine (DEA) and tris(hydroxymethyl) aminomethane (TRIS) salts. F Me COO H 2 N (CH 2 ) 2 OH (CH 2 ) 2 OH H 3 N CH 2 OH CH 2 OH CH 2 OH -+ or + FDEA forms no ladders, nor any other extended motif.Two anions and two cations use their NH 2 + and COOfunctionality to form a discrete R 4 4 (12) ring. Instead of linking adjacent rings, one ethanolamine OH donates a hydrogen bond to the same carboxylate O atom already accepting from NH, thus appending another R 2 1 (7) ring to either side of the main ring. The other ethanolamine OH can link to a carboxylate O atom across the large ring, but its disorder suggests limited importance. Hydroxyl O atoms ...

The poorly water-soluble drug diclofenac [2-(2,6-dichloroanilino])phenylacetic acid, D] is a potent anti-inflammatory agent and is also used to treat solar keratoses. Salt formation may optimize its physico-chemical properties for diverse applications since the counter-ion can profoundly affect melting point, solubility, and the tensile strength of compacts. Crystal structures are known for 22 salts of D from the CSD and 6 from our laboratories. Starting with the t-butylammonium (tBut) salt, we compare systematically the structure and properties of 3 salts with larger organic moieties (cyclohexyl, cHex; benzyl, Benz; 1-adamantyl, Adam, CSD refcode PUHTIX) and 3 salts in which 1,2, and all 3 methyl groups of tBut are replaced with hydroxymethyl (AMP1; AMP2; Tris, TUDPIR). In all these cases the NH3 + group is retained.Crystalline RNH3 + -OCO salts typically create hydrogen-bonded (HB) columns, built most commonly from successive R4 3 (10) rings around a 21 axis or else from alternating R4 4 (12) and R4 2 (8) rings around inversion centers. One O atom accepts two HB; the other, just one. Diclofenac salts have an extra donor: the NH group, which can donate an intramolecular HB to the second O atom. Whereas tBut takes the R4 4 (12) and R4 2 (8) form, cHex and Adam adopt R4 3 (10), while Benz makes distorted R4 4 (12) rings, accompanied by a drastic drop in melting point. Aqueous solubility decreases as the number of carbon atoms increases. In AMP1 the columns of R4 3 (10) rings are retained, the hydroxyl group donating a third HB to a carboxylate O atom. A drastic change to HB layers with van der Waals interactions between them is found with AMP2 and Tris. Melting points increase from AMP1 to AMP2 to Tris; but aqueous solubility decreases despite the increasing hydrophilicity of the counterion, suggesting the overriding importance of attractive interactions in the crystal. The tensile strength of compacts is disappointingly poor (< 1 MPa) even for the layer structures where slip planes beneficial to compaction might be expected. We thank the UK National Crystallography Service for data collection.