http://www.mdpi.com/journal/marinedrugs/special_issues/circ-dichroism-md/ Dear Colleagues, Complete characterization of the structure of a molecule requires both the evaluation of its connectivity and the determination of its stereochemistry. While in many cases the relative configuration is accessible by NMR techniques, knowledge of the absolute configuration mostly requires an X-ray structure determination. In cases where suitable crystals are not available, which is quite often the case for natural compounds, electronic CD spectroscopy (ECD) is a powerful tool to obtain the required information. Based on CD spectra the absolute configuration can be obtained in different ways. An entirely experimental approach is the comparison of the measured CD spectrum of the compound to be analyzed with the spectra of compounds of known stereochemistry. Another possibility is the application of so-called sector rules. Moreover, today modern quantum-chemical methods offer an additional possibility which is the comparison of the experimental spectrum with one calculated assuming a certain absolute configuration. In cases where the signs of the calculated and measured Cotton effects agree, the assumed stereochemistry is most likely correct. If not, the model has to be changed until coincidence between measured and calculated spectra is achieved. This might be quite laborious, especially in cases where the molecule has more than one chiral element (asymmetric atom, chiral axis, etc.) and if the molecule is flexible. In cases where the molecule has no suitable electronic chromophore vibrational CD spectroscopy (VCD) can also be applied. Prof. Dr. Gerhard Raabe Guest Editor Submission All manuscripts should be submitted to marinedrugs@mdpi.com with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website. Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed Open Access monthly journal published by MDPI. Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this Open Access journal is 1400 CHF per accepted paper.