Is there a limit to the size of the molecule that can be characterized directly by x-ray crystal diffraction? There is, says A. L. Patterson of the Institute for Cancer Research and the Lankenau Hospital Research Institute. With considerable struggle one can do a molecule with 25 to 50 atoms, he declares, but the boundary of practically solvable molecules is about 100 atoms.
"There is almost no doubt that continuation of x-ray diffraction work on crystals of simple proteins will lead to the elucidation of their atomic arrangements within the next few years." This side of the coin is advocated by David Harker of Brooklyn Polytechnic Institute. Such giant molecules as hemoglobin and the nucleic acid derivatives can be mapped accurately by diffraction methods, he claims. In a goodnatured disagreement during the symposium on crystal structure by diffraction, Harker told the Division of Physical and Inorganic Chemistry that full characterization of large molecules is simply a matter of time and hard work.
-W.A. Noyes, Urbana, Ill., May 10, 1935
Reminiscences of American Chemical Society San Francisco 1910 Meeting
Chemical & Engineering News, June 20, 1935