Photophysical studies of local anesthetics, tetracaine and procaine: drug aggregations.

摘要: The effects of solvent and concentration on the photophysical properties tertiary amine local anesthetics, tetracaine procaine were studied experimentally using low temperature (77 K) emission spectroscopy confirmed theoretically a HAM/3 method. For free base in methylcyclohexane, broad fluorescence band observed at approximately 375 nm for concentrations greater than 1 x 10(-3) M is assigned to molecular self-associated species. disappearance this ethanol (i.e. model hydrophobic environment) indicates tendency neutral towards hetero-association. In an aqueous solution procaine.HCl, centered 400 detected even as 10(-4) attributed charged aggregates procaine.HCl. Two general observations procaine, dibucaine are noted: (1) monocation anesthetics solutions give identical properties, suggesting that drug species H+ dissociative, (2) lowest singlet excited state calculated have charge-transfer character originating from non-bonding electron N group pi orbital aromatic ring. possible pharmacological implications deprotonation, aggregations excitations basis anesthesia discussed.