Synthesis, characterization and electrochemical studies of osmocenyl alcohols with biomedical applications

[摘要] English: A series of osmocene-containing carboxylic acids, Oc(CH2)mCOOH where m = 1, 2 and 3, andosmocene-containing alcohols, Oc(CH2)nOH where n = 1, 2, 3 and 4, were obtained in multiplesynthetic steps and characterised with the aid of infrared spectroscopy, 1H nuclear magneticresonance spectroscopy, elemental analysis and melting point measurements. New methods weredeveloped for the synthesis of these osmocene-containing carboxylic acids and alcohols.The structures of 2-osmocenylacetonitrile (monoclinic, P21/c, Z = 4, R = 0.057) and2-osmocenylethanol (trigonal, P-3, Z = 18, R = 0.092) were determined by single crystal X-raycrystallography. The alcohol, 2-osmocenylethanol, showed an extensive hydrogen bonding networkinvolving the OH functionalities of six neighbouring molecules, arranged in a hexagonal pattern.Electrochemical studies, utilising cyclic voltammetry, were performed on all compoundssynthesised, including precursor compounds. Electrochemical experiments were conducted inDCM and 0.1 M [NBu4][B(C6F5)4] as supporting electrolyte. A trend was observed between thenumber of –CH2�?spacers and the formal reduction potentials (E°´) for both the carboxylic acidsand alcohols. The formal reduction potentials for both the carboxylic acids and the alcohols werefound to decrease as the number of –CH2�?spacers increased. Dimerisation of the osmocenylmoiety, similar to the known dimerisation of ruthenocene, was observed. It was found that thedegree of dimerisation diminishes as the number of –CH2�?groups increases for both the osmocenecontainingcarboxylic acids and alcohols. The formal reduction potentials for 2-osmocenylethanoicacid, 3-osmocenylpropanoic acid and 4-osmocenylbutanoic acid are 418 mV, 357 mV and 317 mV,respectively. The formal reduction potentials for osmocenylmethanol, 2-osmocenylethanol,3-osmocenylpropanol, and 4-osmocenylbutanol, are 410 mV, 340 mV, 313 mV and 321 mV,respectively. Dimerisation was observed electrochemically for 2-osmocenylethanoic acid,3-osmocenylpropanoic acid, 2-osmocenylethanol and 3-osmocenylpropanol. No dimerisation wasobserved electrochemically for 4-osmocenylbutanoic acid and 4-osmocenylbutanol.

[发布机构] University of the Free State