Thermal behavior of benzoic acid/isonicotinamide binary cocrystals

DOI: 10.1021/acs.cgd.5b00351

Authors: Asma Buanz (University College London) , Tim Prior (University of Hull) , Jonathan Burley (University of Nottingham) , Bahijja Tolulope Raimi-Abraham (University College London) , Richard Telford (University of Bradford) , Mike Hart (Diamond Light Source) , Colin C. Seaton (University of Bradford) , Philip J. Davies (TA Instruments) , Ian J. Scowen (University of Lincoln) , Simon Gaisford (University College London) , Gareth Williams (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystal Growth & Design , VOL 15 (7) , PAGES 3249–3256

State: Published (Approved)
Published: May 2015
Diamond Proposal Number(s): 7782

Abstract: A comprehensive study of the thermal behavior of the 1:1 and 2:1 benzoic acid/isonicotinamide cocrystals is reported. The 1:1 material shows a simple unit cell expansion followed by melting upon heating. The 2:1 crystal exhibits more complex behavior. Its unit cell first expands upon heating, as a result of C–H···π interactions being lengthened. It then is converted into the 1:1 crystal, as demonstrated by significant changes in its X-ray diffraction pattern. The loss of 1 equiv of benzoic acid is confirmed by thermogravimetric analysis–mass spectrometry. Hot stage microscopy confirms that, as intuitively expected, the transformation begins at the crystal surface. The temperature at which conversion occurs is highly dependent on the sample mass and geometry, being reduced when the sample is under a gas flow or has a greater exposed surface area but increased when the heating rate is elevated.

Journal Keywords: Crystals; Differential scanning calorimetry; Materials; Molecular interactions; Physical and chemical processes

Subject Areas: Chemistry, Materials


Instruments: I12-JEEP: Joint Engineering, Environmental and Processing

Added On: 30/05/2015 13:50

Discipline Tags:

Chemistry Materials Science Organic Chemistry

Technical Tags:

Diffraction