Control of Liquid Crystallinity of Diazadibenzoperylene Dyes by Covalent and Hydrogen-Bonded Attachment of Mesogens We thank P. Zell for his assistance in the practical work, Frau G. Dörfner and Prof. U. Thewalt (Sektion Röntgenbeugung, Universität Ulm) and Dr. B. Heise (Abteilung Experimentelle Physik, Universität Ulm) for X-ray diffraction studies. Financial support from the Deutsche Forschungsgemeinschaft (Habilitandenstipendium for F.W.), the Fonds der Chemischen Industrie (Liebig-Stipendium for F.W.), and the Dr. Otto Röhm Gedächtnisstiftung is gratefully acknowledged.