TOWARDS THE TRANSFER OF CHIRALITY FROM MOLECULAR MOTORS TO BIARYLS VIA NON-COVALENT INTERACTIONS

• Main Author: Jefri
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/34041
• Institution: Institut Teknologi Bandung

Chirality is a property of molecules which plays a big role in many aspects of living systems. Since its discovery by Louis Pasteur in 1848, much research on the chirality of both natural and synthetic compounds has been carried out. One of the most interesting topics in this field is the chiral induction, in which chirality is transferred from a chiral molecule to an achiral molecule. In this research, a series of complexes was designed for chirality transfer from a chiral ‘first-generation’ biphenol molecular motor to conformationally flexible biaryls, such as 3,3’-bipyridine, 4,4’- biisoquinoline, 1,1’-dimethyl-4,4’-biisoquinoline, and 1,1’-diphenyl-4,4’- biisoquinoline through hydrogen bonding. The biphenol molecular motor was successfully synthesized in three reaction steps, namely Friedel-Crafts alkylation and subsequent acylation, McMurry homocoupling, and deprotection of methoxy groups in good yield for each step (59–74%). Both enantiomers of the biphenol motor were obtained in high enantiomeric excess (>99%) from resolution of the synthesized motor with (8S,9R)-N-benzylcinchonidinium chloride using either ethyl acetate or acetonitrile as the solvent. Each of the four biaryls was synthesized in one reaction step, either Pd-catalyzed cross coupling, Ni-catalyzed homocoupling, or 1,4- functionalization in low to moderate yields (5–49%). Furthermore, photochemical and thermal isomerization steps of bismethoxy motor, an intermediate in the synthesis of biphenol motor, were studied by means of UV-Vis and 1H NMR spectroscopy. The results showed that the introduction of the methoxy group in the motor does not have a significant influence on the thermal isomerization steps. NMR study revealed that there were no hydrogen bonding between the biphenol motor with either 3,3’- bipyridine or 4,4’-biisoquinoline. Similar result was obtained when the biaryl was substituted with chiral aliphatic diamines. A new design of complex for chirality transfer employing a pyridine-based molecular motor was constructed, but attempts on the synthesis of the motor scaffold were unsuccessful.