ABSTRACT
Although the appearance and shape of crystals have caught attention since antiquity, the rst scientic description of crystals dates back to 1611 when Johannes Kepler suggested that hexagonal form of snowakes is due to regular packaging of spherical water particles [1]. Later discoveries of René Just Haüy, in 1784 [2] led to idea that crystals are essentially regular arrays of packed atoms or molecules. During the nineteenth century, principles of crystal composition and symmetry were worked out, but it was not until discovery of x-rays in 1895 by Wilhelm Röntgen [3] before x-ray crystallography became possible. In 1912 in a historical conversation between Max von Laue and Paul Peter Ewald, it was suggested that crystals could be used for diffraction of x-rays, and the rst diffraction images using copper sulfate crystals were indeed recorded on photographic lm [4]. The rst crystal structures of any compound-those of NaCl and KCl-were solved by William Lawrence Bragg already in 1913 [5]. In the following three decades, crystal structures of several organic molecules were solved, notably hexamethylenetetramine [6], long-chain fatty acids [7], phthalocyanine [8], penicillin [9], and vitamin B12 [10]. However, due to technical limitations, it was not until 1958 when rst high-resolution protein structure of myoglobin was solved [11].
