Instrumentation and Services
The Department of Chemistry's X-Ray Diffraction Facility offers single-crystal data collection and structure determination services at the highest level of the art on all kinds of molecules, including inorganic, organic, organometallic and biological samples. That also incudes data collection on protein crystals. Of course, our instruments cannot compete with a synchrotron, but our modern ImuS microfocus X-ray tubes compare favorably with (and, in terms of flux density, possibly outperform) all rotating anode generators currently present on MIT campus. Thanks to our modern equipment, which is carefully maintained, and recent progress in methods and software development, we also offer determination of absolute configuration of chiral compounds from light-atom structures where oxygen is the heaviest element present (at least one oxygen for every 10 carbon / nitrogen atoms is recommended). This service can be vital for pharmaceutically relevant molecules or natural compounds.
While the Chemistry Departments Diffraction Facility is primarily a single-crystal facility, we also offer transmission-mode (in capillaries) powder diffraction at temperatures from 100K to 500K. Transmission-mode powder diffractomery is particularly interesting when only small amounts of sample are available, because one only needs to fill a tube with an inner diameter of 0.64 mm about 5 mm high, which corresponds to approximately 1.6 cubic millimeters of tightly packed sample. With very careful sample preparation one can further reduce the amount of sample needed to approximately 1 cubic millimeter. Details about variable-temperature transmission-mode powder diffraction can be found here.
Our Facility also offers data collection and structure determination to for-profit customers. For details please contact Peter Mueller or Rich Wilk.
The Facility is equipped with state-of-the-art and versatile Bruker diffracton equipment that allows collecting complete and highly redundant datasets in any given Laue class meeting or exceeding the International Union of Crystallography requirements for good data. These diffractometers are coupled to extraordinarily sensitive Bruker APEX and APEX2 CCD detectors that give rise to high-resolution data even on very small crystals (down to 10µm). Data collection can be performed using Mo or Cu radiation, depending on the requirements of the project. Mo radiation gives rise to higher resolution data and is the preferred wavelength for most routine samples. Cu radiation is required to obtain anomalous signal from light-atom structures and is sometimes needed to obtain a good diffraction pattern from very small crystals.