Novel anion recognition host molecules, tris-1,10-phenanthroline cobalt(III) and bis-2,2'-bipyridine mono-1,10-phenanthroline ruthenium(II) complexes bearing fused dipyrrolylquinoxaline moieties have been synthesized. As determined by UV-vis spectroscopic and electrochemical studies, these metal complexes bind fluoride with high affinity in polar media both in absolute terms and relative to the metal-free phenanthroline dipyrrolylquinozaline precursor from which they are derived (fluoride is bound to the tris-1,10-phenanthroline cobalt(III) dipyrrolylquinoxaline system with a 1:1 binding constant of 54 000 M-1 in DMSO). The large observed binding constants are ascribed to two factors, (i) the presence of a phenanthroline-coordinated cationic charge that decreases the electron density on the pyrrole NH protons and (ii) pure electrostatic effects.

Phenylacetylene (PA, C8H6) on Cu(111) has been studied using temperature-programmed desorption (TPD) and X-ray and ultra-violet photoelectron spectroscopy (XPS and UPS). Dosed at 100 K, physisorbed and chemisorbed PA are readily distinguished in TPD; the former desorbs at 165 K and the latter as three peaks360 (γ2), 410 (γ1), and 500 K (γd). The most intense, γ1, is attributed to cross-bridged PA with di-σ bonds of the acetylene carbons to Cu. The γ2 peak is attributed to a vinylidene C8H6 species with the terminal carbon of the vinyl group σ-bonded to Cu. Rehydrogenation of a partially dehydrogenated PA, e.g., C8H5, accounts for the highest temperature PA peak, γd. According to XPS, at saturation monolayer coverage, there is one chemisorbed PA for every 4 surface Cu atoms. At this coverage, a local 4 × -rect arrangement of cross-bridged PA adequately accounts for our results. For monolayer PA, the work function at 100 K is 0.75 eV below that of Cu indicating electron density shifts from PA toward Cu. The HOMO level of chemisorbed PA is located 3.5 eV below the Fermi level. Annealing a saturated monolayer to 810 K leaves 23 ± 2% of the initial carbon consistent with observed desorption of hydrogen, acetylene, and styrene. Hydrogenation of cross-bridged PA, not vinylidene, accounts for the formation of styrene.

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The synthesis of four new analogues of motexafin gadolinium (MGd), a gadolinium(III) texaphyrin complex in clinical trials for its anticancer properties, is described. These new derivatives contain either 1,2-diaminobenzene or 2,3-diaminonaphthalene subunits as the source of the imine nitrogens and bear multiple 2-[2-(2-methoxyethoxy)ethoxy]ethoxy (PEG) groups, on either meso aryl or beta-pyrrolic substituents, to increase their water solubility. All four analogues were found to be more active in vitro than the parent system MGd as judged from cell proliferation assays using the PC3 and A549 cell lines.

The synthesis of a new PEG 3 -solubilized gadolinium texaphyrin (Gd-Tex) conjugate containing a malonate-Pt(NH 3 ) 2 moiety is described. The effect of the tumor localizing Gd-Tex macrocycle on platinum activity was evaluated in cell culture. The malonate moiety, analogous to that present in carboplatin, is expected to release Pt(NH 3 ) 2 under physiological conditions. The half-life in phosphate-buffered saline was found to be ca. 3 days at room temperature, and the hydrolytic product released from the conjugate was collected and confirmed as Pt-based by flameless atomic absorption spectrophotometry. Anti-proliferative activity was tested using A549 human lung cancer and A2780 human ovarian cancer cell lines. In both cell lines, the activity of the Gd-Tex conjugate was found to be similar to that of carboplatin. Efficacy against a Pt-resistant ovarian cell line greater than that displayed by carboplatin was also observed.

Conjugates between methotrexate (MTX, Matrex, N-[4-[[(2,4-diamino-6-pteridinyl)methyl]methylamino]benzoyl]-l-glutamic acid), an antifolate cancer chemotherapeutic to which resistance is often observed, and motexafin gadolinium (MGd), an experimental agent demonstrating selective tumor localization, are described. These systems were prepared in order to test whether linking these two species would produce agents with enhanced activity relative to MTX alone. Both ester- and amide-linked conjugates were synthesized starting from MGd and MTX. The ester conjugate showed greater in vitro anti-proliferative activity against the A549 lung carcinoma cell line at short incubation times than did MTX alone. Neither the amide conjugate, nor MGd, showed any observable activity under these in vitro conditions. These results are rationalized in terms of enhanced cellular uptake of both the ester and amide conjugates that is coupled with an effective rate of release (e.g., inherent or enzyme-mediated hydrolysis) in the case of the ester-linked conjugate, but not the corresponding amide system.

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Tris(8-hydroxyquinoline)aluminum (III) (Alq 3 ), widely used in organic light-emitting diodes, has been examined on Cu(111) using two-photon photoemission (2PPE) spectroscopy supplemented by temperature-programmed desorption. Relative to Cu(111), clean and covered with typical aromatic molecules, the 2PPE intensities of Alq 3 on Cu(111) are very strong. As a function of coverage, the interfacial energy level alignment of Alq 3 with Cu(111) has been mapped and accords with an interface dipole model. In the electron time-of-flight spectrum of 2PPE, significant intensity extends to relatively long times and is ascribed to Alq 3 photoluminescence rather than electron emission.