Contents -- 1 Introduction and historical background -- 1.1 Introduction -- 1.2 Definitions -- 1.2.1 Polymorphism -- 1.2.2 Pseudopolymorphism, solvates, and hydrates -- 1.2.3 Conventions for naming polymorphs -- 1.3 Is this material polymorphic? -- 1.3.1 Occurrence of polymorphism -- 1.3.2 Literature sources of polymorphic compounds -- 1.3.3 Polymorphic compounds in the Cambridge Structural Database -- 1.3.4 Powder Diffraction File -- 1.3.5 Patent literature -- 1.3.6 Polymorphism of elements and inorganic compounds -- 1.3.7 Polymorphism in macromolecular crystals -- 1.4 Historical perspective -- 1.5 Commercial/industrial importance of polymorphism-some additional comments -- 2 Fundamentals -- 2.1 Introduction -- 2.2 Thermodynamics of polymorphic molecular crystals -- 2.2.1 The Phase Rule -- 2.2.2 Thermodynamic relations in polymorphs -- 2.2.3 Energy vs temperature diagrams-the Gibbs free energy -- 2.2.4 Enantiotropism and monotropism -- 2.2.5 Phase diagrams in terms of pressure and temperature -- 2.2.6 Heat-of-transition rule -- 2.2.7 Heat-of-fusion rule -- 2.2.8 Entropy-of-fusion rule -- 2.2.9 Heat-capacity rule -- 2.2.10 Density rule -- 2.2.11 Infrared rule -- 2.3 Kinetic factors determining the formation of polymorphic modifications -- 2.4 Structural fundamentals -- 2.4.1 Form vs habit -- 2.4.2 Structural characterization and comparison of polymorphic systems -- 2.4.3 Presentation of polymorphic structures for comparison -- 3 Controlling the polymorphic form obtained -- 3.1 General considerations -- 3.2 Aggregation and nucleation -- 3.3 Thermodynamic vs kinetic crystallization conditions -- 3.4 Monotropism, enantiotropism, and crystallization strategy -- 3.5 Concomitant polymorphs -- 3.5.1 Crystallization methods and conditions -- 3.5.2 Examples of different classes of compounds -- 3.5.3 The structural approach -- 3.6 Disappearing polymorphs.

3.7 Control of polymorphic crystallization by design -- 4 Analytical techniques for studying and characterizing polymorphs -- 4.1 Introduction -- 4.2 Optical/hot stage microscopy -- 4.3 Thermal methods -- 4.4 X-ray crystallography -- 4.5 Infrared spectroscopy -- 4.6 Raman spectroscopy -- 4.7 Solid state nuclear magnetic resonance (SSNMR) spectroscopy -- 4.8 Scanning electron microscopy -- 4.9 Atomic force microscopy (AFM) and scanning tunnelling microscopy (STM) -- 4.10 Density measurements -- 4.11 New technologies and 'hyphenated techniques' -- 4.12 Are two samples polymorphs of the same compound? -- 4.13 Concluding remarks -- 5 Conformational polymorphism: intra- and intermolecular energetics -- 5.1 Introduction -- 5.2 Molecular shape and energetics -- 5.3 Intermolecular interactions and energetics -- 5.4 The search for examples of conformational polymorphism -- 5.5 Presenting and comparing conformational polymorphs -- 5.6 Some examples of conformational polymorphism -- 5.7 What are conformational polymorphs good for? -- 5.8 Computational studies of the energetics of polymorphic systems -- 5.9 Some exemplary studies of conformational polymorphism -- 5.10 The computational prediction of polymorphs -- 6 Polymorphism and structure-property relations -- 6.1 Introduction -- 6.2 Bulk properties -- 6.2.1 Electrical conductivity -- 6.2.2 Organic magnetic materials -- 6.2.3 Photovoltaicity and photoconductivity -- 6.2.4 Nonlinear optical activity and second harmonic generation -- 6.2.5 Chromoisomerism, photochromism, thermochromism, mechanochromism, etc. -- 6.2.6 Thermal phase changes and the thermosalient effect- 'hopping' or 'jumping' crystals -- 6.3 Molecular properties -- 6.3.1 Infrared and Raman spectroscopy -- 6.3.2 UV/Vis absorption spectroscopy -- 6.3.3 Excimer emission -- 6.3.4 Excited state diffraction studies -- 6.4 Photochemical reactions.

6.5 Thermal reactions and gas-solid reactions -- 6.6 Pressure studies -- 6.7 Concluding remarks -- 7 Polymorphism of pharmaceuticals -- 7.1 Introduction -- 7.2 Occurrence of polymorphism in pharmaceuticals -- 7.2.1 Drug substances -- 7.2.2 Excipients -- 7.3 Importance of polymorphism in pharmaceuticals -- 7.3.1 Dissolution rate and solubility -- 7.3.2 Bioavailability -- 7.4 Microscopy and thermomicroscopy of pharmaceuticals -- 7.5 Thermal analysis of pharmaceuticals -- 7.6 The importance of metastable forms -- 7.7 The importance of amorphous forms -- 7.8 Concluding remarks -- 8 Polymorphism of dyes and pigments -- 8.1 Introduction -- 8.2 Occurrence of polymorphism among pigments -- 8.3 Polymorphism in some specific groups of pigments -- 8.3.1 Quinacridones -- 8.3.2 Perylenes -- 8.3.3 Phthalocyanines -- 8.3.4 Some other pigments-old and new -- 8.4 Isomorphism of pigments -- 9 Polymorphism of high energy materials -- 9.1 Introduction -- 9.2 The 'alphabet' of high energy molecular materials -- 9.3 Individual systems -- 9.3.1 Aliphatic materials -- 9.3.2 Aromatic materials -- 10 Polymorphism and patents -- 10.1 Introduction -- 10.2 Ranitidine hydrochloride -- 10.3 Cefadroxil -- 10.4 Terazosin hydrochloride -- 10.5 Aspartame -- 10.6 Concluding remarks -- References -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- U -- V -- W -- X -- Z.