Fluorous modification of 2,2′-bipyridine

A series of 2,2′-bipyridines featuring fluorinated alkyl groups [(CH2)3(CF2)xCF3: x = 0, (1); 5, (2); 7, (3); 9 (4)] appended in the 4 and 4′ positions have been prepared. 1–4 were characterized by spectroscopy and physical methods including partition coefficient (biphase: perfluoromethylcyclohexane/toluene) and cyclic voltammetry (THF). Ab-initio calculations of vertical ionization potentials (VIPs) for 1–4 confirm the insulating role of the methylene spacers as the electrochemical reduction potentials of 1–4 are almost identical to that of 2,2′-bipyridine. Calculations for (CH2)nCF3 derivatives (n = 0–10) describe a limit for impact of the CF3 group through 9–10 methylenes. From both physical and theoretical data fluorinated alkyl groups of the formula (CH2)3(CF2)xCF3 [x = 0–9] are inductively equivalent to a hydrogen substituent when appended to the bipyridine moiety.

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