Solid-State Characterization of Complexes

Whether the guest substance has imdergone any changes or not is observed via thermoanalytical methods [47]. Melting, evaporation, decomposition, oxidation or 

The microscopic aspects of the raw material (cyclodextrin and the guest substances, respectively) and the product obtained by co-precipitation/evaporation [48] are studied by SEM. The morphologies of pure drug and carriers and their combinations are studied by SEM analysis. 

The crystal state of the raw material and the product and their differences are seen under electron microscope, revealing the formation of the inclusion complexes [49]. 

3 X-ray Diffractometry and Single-Crystal X-ray Structure Analysis Liquid guest molecules have no diffraction pattern of their own, then there is a difference in the diffraction of newly formed complex and uncomplexed cyclodextrin, indicating the complex formation [57]. In the case of solid guest compound, the dif-fractogram of newly formed complex and mechanical mixture of guest and cyclodextrin molecule are compared [50]. 

The crystalline nature of the drug and its diffraction pattern is altered by the complex formation of drug with cyclodextrin. There is sharpening of the existing peaks, appearance of a few new peaks and shifting of certain peaks. On the other hand, formation of amorphous complexes leads to the disappearance of certain peaks or the peaks become less sharp than those of the pure compound or physical mixture [9]. 

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