Frequently asked questions
How do you determine the purity of fullerene derivatives?
The purity of our fullerene derivatives is determined by HPLC and 1H NMR analysis. In this way, we check for the purity of the fullerene compound (by HPLC), for the correct structure (by NMR and HPLC), and for residual solvent residues (by NMR).
For our products, we have strict rules regarding their minimum purity, and how this is to be determined. The analytical data of a specific compound or batch are always available upon request. Just send us an e-mail and we can send you further information.
Why is the color of the PCBM that I received recently different from that of a previous batch?
This is a normal phenomenom, and nothing to worry about. The color of solid fullerene derivatives sometimes varies, because of small differences between batches in for example the particle size and powder density. As a result, the color of the PCBM can vary between brown and black. This also happens with many other fullerene derivatives.
Do you have fullerene derivatives with a different LUMO level than PCBM?
Yes, we most certainly do. The LUMO level of fullerene derivatives can be varied by changing the type and degree of chemical derivatization.
Derivatives that have LUMO levels above that of PCBM are, for example, IPH, bisPCBM, and ICBA. These compounds have LUMO levels that are 30-150 mV above that of PCBM. It is possible to go even further. Derivatives of C60-fullerene with a LUMO level below that of PCBM are quite rare, but we sell KLOC-6, which has a LUMO level approximately 150 mV below that of PCBM.
Why are most fullerene derivatives listed as 99% purity only?
This is common practice for fullerene derivatives. We could easily label all our materials as 100% pure by HPLC, but we don’t. Why? Well, first of all small amounts of solvent residues are often present and these are not detected in the HPLC measurement, only in 1H NMR. Second, for C60 fullerene it is relatively easy to get >99.5% purity by HPLC. However, upon derivatization, such a high purity becomes more complicated to reach. The HPLC will often give a single peak, thus suggesting 100% purity, but evidently the side-products are difficult to separate from the main product because of the small differences between the compounds.
What kind of impurities are present in your fullerene derivatives?
Common impurities are isomers of the main compound (e.g. ethyl ester instead of methyl ester in PCBM), as well as small amounts of oxidized fullerenes.
I can’t find the derivative that I want to buy. Do you still have it?
There are many fullerene derivatives that were reported in literature, and they may also be available from Solenne. It is simply not possible to list our complete inventory on the website. In some cases, the compound may have been synthesized and supplied by us, but it is not mentioned in the article. So don’t hesitate to contact us!