Fluorous modification of 2′-bipyridine

A series of 2,2'-bipyridines featuring fluorinated alkyl groups [(CH2)(3)(CF2)(x)CF3: 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)(n)CF3 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)(x)CF3 [x = 0-9] are inductively equivalent to a hydrogen substituent when appended to the bipyridine moiety. (C) 2005 Elsevier B.V. All rights reserved.