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Chiral recognition of two binaphthyl derivatives and three benzodiazepines were studied by use of polymeric surfactants in electrokinetic chromatography. Four specific dipeptide terminated (multichiral) micelle polymers were synthesized for this study. These include poly (sodium-N-undecanoyl-L-alanyl-leucinate)-(poly L-SUAL), poly (sodium-N-undecanoyl-L-valyl-leucinate) (poly L-SUVL), poly (sodium-N-undecanoyl-Lseryl-leucinate) (poly L-SUSL), and poly(sodium-N-undecanoyl-L-threonyl-leucinate) (poly L-SUTL). In addition to the chiral separation study, the physicochemical properties (critical micelle concentration and specific rotation) of each polymer were investigated. The molecular weights of the various dipeptide-terminated micelle polymers were determined using analytical ultracentrifugation. These dipeptide-terminated micelle polymers were designed to study the effect of the extra heteroatom at the polar head group of the micelle polymer (i.e., poly L-SUSL compared to poly L-SUAL and poly L-SUTL compared to poly L-SUVL) on the enantiomeric separation of the binaphthyl derivatives and benzodiazepines. The synergistic effect of three chiral centers (poly L-SUTL) provided improved resolution over that of two chiral centered dipeptide-terminated micelle polymer in the case of (+/-)-temazepam, (+/-)-oxazepam, (+/-)-binaphthol, and (+/-)-binaphthol phosphate. The chiral recognition mechanisms in these cases were additionally controlled by the presence of the extra heteroatom located on the polar head group of the micelle polymers.

The absorption and fluorescence spectral characteristics of 9-acridinecarboxylic acid (9-ACA) and 9-(methoxycarbonyl)acridine (9-MCA) were studied in a series of organic solvents and in aqueous solutions. Fluorescence quantum yields (Φf) and lifetimes (τf) of the compounds were measured in these solvents. Unlike 9-anthroic acid (9-AA), as reported in the literature, no large Stokes-shifted fluorescence emission band was observed for 9-ACA and 9-MCA in neutral organic solvents or water. The absence of large Stokes-shifted emission in the case of 9-ACA and 9-MCA suggests the existence of a charge-transfer emitting state in 9-AA in which the carboxyl group is nearly coplanar with the aromatic ring. The Φf values for both compounds increase as a function of hydrogen-bonding capacity of the solvents. In near neutral to slightly acidic solutions, 9-ACA exists mainly in the zwitterionic form. Both 9-ACA and 9-MCA form monoprotonated species in moderately concentrated acid solutions. The acidium cation of 9-AA formed in the excited state in moderately concentrated acid solution reorganizes to produce a carbocation centered at the carbon atom of the carboxyl group. However, there was no indication of the formation of such acidium cations in the case of 9-ACA and 9-MCA even in concentrated perchloric acid medium. The pK as of various prototropic equilibria involved in the ground electronic state of the compounds were estimated. Semiempirical AM1 calculations were performed to obtain the energies of the various configurations of 9-AA and 9-ACA in the ground (S0) as well as in the lowest excited singlet (S1) electronic state. The results suggest that the COOH group is oriented at an angle of ∼55° with respect to the aromatic ring in the S0 state in both the molecules. However, in the S1 state, it approaches coplanarity with the aromatic ring. The calculated bond lengths, charge densities, and dipole moments suggest that the resonance charge transfer from the aromatic ring to the COOH group increases in the S1 state of 9-AA. However, despite the decrease of twist angle of the COOH group, no significant charge transfer was observed in 9-ACA. The charge density data indicate that the ring nitrogen and the carbonyl oxygen of the COOH group become more basic upon electronic excitation.

A modified polyamidoarnine-starburst dendrimer (PAMAM-SBD). 16-cascade: ( 1,4-diaminobutane)[4-1,4]:( 1.6-diaza-7-0x0-nonylidene)2:propanoic acid methyl ester (DABD), was synthesized and used as a carrier in electrokinetic capillary chromatography. The utility of DABD is demonstrated with the separation of a mixture of naphthalene derivatives and five neutral aromatic molecules without the need for an organic solvent as a modifier. Separation of a mixture of five neutral aromatic molecules were optimized through dendrimer concentration, pH, and organic modifier.The modified polyamidoamine-starburst dendrimer offered selectivity for polynuclear aromatic hydrocarbons as well as naphthalene based derivatives. However, DABD did not provide as much selectivity €or neutral aromatic compounds in the presence of organic modifier. 611

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