About the service

The X-ray Crystallography Laboratory of the Weizmann Institute is both a service and a user facility. It is well equipped for the single crystal diffraction experiments needed for structural biology and chemistry research. We apply a variety of experimental methods to these investigations.

Small Molecules

Since each crystal is unique, we tailor each experiment to the individual sample and offer expertise in the following areas:

  1. Air-sensitive crystals
  2. Unusually small crystals
  3. Low-temperature data collection
  4. Disorder or twinning
  5. Absolute structure determinations, including all-light atom structures
  6. Database searches

A structural determination of molecular crystals will typically involve the following:

  1. Sample inspection under the polarizing microscope
  2. Determination of unit cell parameters, the crystal system, and space group
  3. Structure solution and refinement
  4. Creation of tables in CIF and other formats
  5. Publication-ready molecular and packing plots

The measurements of organic and organometallic materials are performed using a Bruker Kappa ApexII CCD (a charge-coupled device) diffractometer or Nonius KappaCCD diffractometer mounted on a FR590 generator with MiraCol optics, both utilizing Mo radiation. A Nonius Mach3 Kappa full 4-circle diffractometer mounted on a FR590 generator is also available with Cu radiation. Data collection may be performed at either LN or ambient temperatures. Low temperature has many benefits for X-ray structure determination, including better quality data in less time than room-temperature work and the ability to handle highly reactive compounds with minimal fuss. We typically collect data at 100K, but on occasion, destructive phase transitions require data collection at higher temperatures.

We freeze and store under liquid nitrogen air-sensitive small molecules as well as unstable organic and organometallic crystal samples.

Macro Molecular

For the Structural Biologists, the X-ray laboratory is a user facility. Macromolecular crystallographic measurements are made on two Rigaku RAxis IV++ systems. The image plate detectors are mounted on either MX-007HF generator equipped with VariMax optics HF or a RU-H3R rotating anode generator equipped with Osmic confocal focusing mirrors. One of these systems is outfitted with a 2-theta stage allowing high-resolution data collection. Both systems are equipped with Oxford cryostream cooling systems for LN (liquid nitrogen), low-temperature measurements. Also available in the laboratory are UV/Visible light-microscopes for sample inspection and mounting as well as a digital camera for crystal photography.

Training is available for users, so that they can perform their own experiments.

We have large, storage dewars to allow our macromolecule users to keep frozen crystals.

 

Linda  J. W. Shimon
Linda J. W. Shimon
Head
Tel. 08-934-6563, 050-832-5575