Synthesis of Molecular Tripods Based on a Rigid 9,9鈥?Spirobifluorene Scaffold

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• 作者：Michal Val谩拧ek ; Kevin Edelmann ; Lukas Gerhard ; Olaf Fuhr ; Maya Lukas ; Marcel Mayor
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：August 15, 2014
• 年：2014
• 卷：79
• 期：16
• 页码：7342-7357
• 全文大小：711K
• ISSN：1520-6904

文摘

The efficient synthesis of a new tripodal platform based on a rigid 9,9鈥?spirobifluorene with three acetyl protected thiol groups in the positions 2, 3鈥?and 6鈥?for deposition on Au(111) surfaces is reported. The modular 9,9鈥?spirobifluorene platform provides both a vertical arrangement of the molecular rod in position 7 and its electronic coupling to the gold substrate. To demonstrate the validity of the molecular design, the model compound 24 exposing a para-cyanophenylethynyl rod is synthesized. Our synthetic approach is based on a metal鈥揾alogen exchange reaction of 2-iodobiphenyl derivative and his subsequent reaction with 2,7-disubstituted fluoren-9-one to afford the carbinol 16. Further electrophilic cyclization and separation of regioisomers provided the corresponding 2,7,3鈥?6鈥?tetrasubstituted 9,9鈥?spirobifluorene 17 as the key intermediate. The molecular structure of 17 was determined by single-crystal X-ray diffraction crystallography. The self-assembly features of the target compound 24 were analyzed in preliminary UHV-STM experiments. These results already demonstrated the promising potential of the concept of the tripodal structure to stabilize the molecule on a Au(111) surface in order to control the spatial arrangement of the molecular rod.