Fund, and the allocation of computer time from the Computer Center of the University of New Brunswick. functional approximation used in the computations. There are very few computations for arene-metal complexes that are of sufficient quality to predict their bond and total energies accurately. In order to determine whether the LCAO-LSD method can generally predict these properties, more computations on a whole series of arene-metal compounds must be performed and compared with accurate experimental data.The magnetic circular dichroism (MCD) and absorption spectra of zinc phthalocyanine (ZnPc) isolated in an Ar matrix have been studied over the range 14700-74000 cm-I. Synchrotron radiation, from the electron storage ring at the Synchrotron Radiation Center, Madison, WI, was used for energies above 33 000 cm-I. The spectra are well resolved, and the MCD permits the determination of excited-state magnetic moments. There is strong evidence that the Pc rings are preferentially oriented with the molecular planes parallel to the deposition window. The data can be reasonably correlated with the old Peel calculation of Henriksson et al., but there is a compelling need for a new calculation that extends to higher energy and includes extensive configuration interaction. (4) Bondybey, V. E.; English, J. H. J . Am. Chem. SOC. 1979, 101, (5) Huang, T. H.; Reickhoff, K. E.; Voigt, E. M. J. Chem. Phys. 1982, (6) Huang, T. H.; Rieckhoff, K. E.; Voigt, E. M.

Peptide mimetics may substitute for carbohydrate antigens in vaccine design applications. At present, the structural and immunological aspects of antigenic mimicry, which translate into immunologic mimicry, as well as the functional correlates of each, are unknown. In contrast to screening peptide display libraries, we demonstrate the feasibility of a structure-assisted vaccine design approach to identify functional mimeotopes. By using concanavalin A (ConA), as a recognition template, peptide mimetics reactive with ConA were identified. Designed peptides were observed to compete with synthetic carbohydrate probes for ConA binding, as demonstrated by enzyme-linked immunosorbent assay and isothermal titration calorimetry (ITC) analysis. ITC measurements indicate that a multivalent form of one particular mimetic binds to ConA with similar affinity as does trimannoside. Splenocytes from mimeotope-immunized mice display a peptide-specific cellular response, confirming a T-cell-dependent nature for the mimetic. As ConA binds to the Envelope protein of the human immunodeficiency virus, type 1 (HIV-1), we observed that mimeotope-induced serum also binds to HIV-1-infected cells, as assessed by flow cytometry, and could neutralize T-cell line adapted HIV-1 isolates in vitro, albeit at low titers. These studies emphasize that mimicry is based more upon functional rather than structural determinants that regulate mimeotope-induced T-dependent antibody responses to polysaccharide and emphasize that rational approaches can be employed to develop further vaccine candidates.

The Judd-Ofelt parametrization scheme for lanthanide 4f -» 4f transition intensities is used to analyze absorption intensity data obtained for a series of Er(III) complexes in aqueous solution. Oscillator strengths are reported for eight multiplet-to-multiplet transition regions of each complex, and values for the Judd-Ofelt intensity parameters, ( = 2,4, 6), are determined and reported for each of the systems. Variations in the values of these parameters from system to system are discussed in terms of structural differences between the complexes (with respect to ligand properties and coordination geometry).

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