Dr. C. Daniliuc

XRay - Service

  • Sample preparation

    You think, you have a crystal…what next???

    • If possible, bring the sample in our department for the first check. For the air- or temperature-sensitive samples please take contact with us.A preliminary assessment of the sample quality will be done (solidified material, glass, microcrystalline powder, etc., is immediately recognized and sorted out on site).
    • A fully completed order form must be submitted for the sample.
    • After the date of receipt the samples are measured. For certain / urgent appointments (for example: accepted publications, Bachelor or Master theses submission), the samples can be favored.
    • The crystal is selected by us, using a microscope equipped with a polarization device and rotary table.
    • The crystal preparation is carried out standard at room temperature in air or with exclusion of air in inert oil (perfluoropolyether, Fomblin Y). For the temperature- and air-sensitive crystals it is possible (according to agreement) to prepare with an "X-Temp 2 System" in an inert gas stream (N2) at temperatures of up to -100 ° C.
    • The selected crystal is attached to the goniometer head, centered and the elementary cell is determined. The finally measurement is then started. This can take from 2 hours to 2-3 days.
    • From the collected data, the structure is determined and refined by us. Solving the structure may take a different time. For simple structures, this can be done within 30 minutes. For the problem structures (strong disordered groups, twinning structures, etc.), up to several days can be necessary.
    • Final data containing all cell parameters and structural information can be received in paper form and as electronic files (only on USB stick) in our X-Ray department.


    Rules/Indication

    • A completed order form (available directly in the department or on request) and a crystalline sample are required for the measurement.
    • We prefer crystals provided within the solvent. DO NOT remove the solvent!!!
    • Samples can be delivered in all common laboratory vessels, e.g. Flasks, NMR tubes, Schlenks, vials, etc., but conditioned if these are very high, too tight or bigger than 100 ml. Large/bigger vessels make the examination with the microscope more difficult.
    • All vessels for the crystallization batches should be clean and dust-free.
    • The solvents used should also be dust-/fiber free. When using solvent mixtures, if the solvents crystallize, it is often difficult to decide which solvent is in the crystal. Please use a maximum of two solvents for crystallization.
    • Please submit only completed order forms.
    • Attention: The desired numbering of the atoms should be taken into consideration!!! No later changing of the atom name will be done.
    • To avoid unnecessary measurements, please enter the cell parameters of known compounds (such as starting material, by-products) into the form.

  • Sample submission

    In any case, the samples should be handed over personally to our department (Ms. B. Wibbeling or Dr. C. Daniliuc), in order to clarify if the crystals are suitable for measurement, if the substance is sensitive to light, air or to moisture, if determination of the absolute configuration of chiral compounds is necessary, etc.

    If your sample has been crystallized in a glove box, we will give you a corresponding instruction. You get from us a prepared box with inert oil on a slide. At the agreed appointment, bring the sample to us.

    For all samples which cannot be placed in the department together with the order form, we agree a measurement appointment date with the exact time of crystal submission (the appointment will be done usually 1 day before the measurement).

  • Results

    The results can be obtained directly in our X-Ray department as a paper form and electronically on the USB stick. If necessary, further discussions concerning the quality of the structure will be discussed directly.

    Attention: Please collect your samples back after the measurement!!!

     

    The measurement, structure solution and structure refinement are carried out by the X-Ray service department. Dr. C. Daniliuc assumes responsibility for crystallographic accuracy and quality. Since a crystal structure determination is considered to be an independent, scientific accomplishment, it is expected that in the case of the inclusion of a structure determined in this way into a diploma or doctoral thesis, the involved employees of the X-Ray department are mentioned in the respective section. In case of a publication the involved X-Ray employees are expected to be accepted as coauthor.

    Unfortunately, many determined structures are only included in diploma and doctoral thesis, but not published further. They are then not included in the crystallographic databases. If no publication is foreseeable, as alternative option, the crystal structure can be stored as "personal communication" directly in the Cambridge Crystallographic Database. For more information please contact Dr. C. Daniliuc.