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A reverse cation-exchange approach is described for the synthesis of hollow PbSe nanospheres, which involves a step wise, in-situ template-based evolution from spherical amorphous Se colloids to Se/[Ag.sub.2]Se core/shell colloids, then to hollow PbSe nanospheres. The characterization results show that hollow PbSe nanospheres with polycrystalline and cubic structure are prepared and the conformation is beneficial to the improvement concerning the applications of PbSe nanostructures.

Size-controllable monodisperse PbSe and PbSe/PbS nanocrystals (NCs) are successfully synthesized with a solvothermal method. These narrow-band-gap semiconductor NCs with tunable size are expected to have potential applications in near- and mid-IR telecommunication laser sources, electroluminescence, and solar cell materials.

Conduction in thin films of PbSe nanocrystals doped by electrochemical gating was studied. Charging the film, with electrons or holes, increases the conductance by order of magnitude and the temperature and electric field dependence of conductance in the film measured between 4.3 and 135 K, were both well described by a variable range hopping model.

The synthesis and characterization of photonucleases N,N'-bis[2-[bis(1H-imidazol-4-ylmethyl)amino]ethyl]-3,6-arcidinediamine and N-[2-[bis(1H-imidazol-4-ylmethyl)amino]-3,6-acridinediamine, consisting of a central 3,6-acridinediamine chromophore attached to 4 and 2 metal-coordinating imidazole rings, respectively, are reported. The data indicates that buffer, pH, Hg(II), Fe(III), Cd(II), Zn(II), V(V), Pb(II), and light can be used to tune DNA cleavage by N,N'-bis[2-[bis(1H-imidazol-4-ylmethyl)amino]ethyl]-3,6-arcidinediamine under physiologically relevant conditions.

The calculation of electronic spectra of lead(II) complexes of some hydroxyflavone molecules by the time dependent density functional theory methodology is reported. The results obtained by taking into account the solvent effect are in very good agreement with the experimental features and lead to a complete assignment of the spectral changes observed upon complexation of these compounds.

The metal-binding specificity and affinity of N-terminal domain in ZntA is investigated. It is found that N1-ZntA could bind both divalent metal ions such as Cd(II), Pb(II) and Zn(II) and monovalent metal ions such as Ag(I), with a stoichiometry of 1 while N2-ZntA can bind Zn(II) and Cd(II) with a stoichiometry of 1 but not Pb(II).

The single crystalline PbMoO4 dendrites were prepared by a simple hydrothermal method in the presence of surfactants. The formation and evolution of dendrites was investigated by transmission electron microscopy, and the results showed that the dendritic structure was achieved through oriented attachment of nanoparticles along crystallographically specific direction.

The anionic framework of the crystal is preserved even during the replacement of cationic sublattice with a different metal ion via reversible place exchange in ionic nanocrystals. This method has ensured that compositional interfaces within the heterostructure are conserved throughout the transformation when it is applied to nanoheterostructures.

The possible mechanisms of phonon scattering by nanostructures and defects in PbTe-X (X = 2%Sb, Bi, or Pb) thermoelectric materials systems are examined. The particle-induced local elastic perturbations have interfered with the phonon propagation pathway, thereby contributing to the reduction in lattice thermal conductivity and increasing the overall thermoelectric figure of merit.

Luciferase (Luc8) is used as a template to direct the synthesis of near-infrared (NIR) light emitting PbS quantum dots (QDs) at ambient conditions to form a Luc8-PbS nanocomplex. The addition of the substrate coelenterazine has helped in nonradiatively transferring the energy produced by Luc8 to PbS QDs via bioluminescence resonance energy transfer (BRET) and has enabled the complex to emit NIR light.

A transient absorption and luminescence study is used for addressing the charge separation, recombination and regeneration reactions at nanostructured metal oxide/PbS quantum dot/organic hole conductor heterojunctions. The studies have shown a correlation between the PbS particle size and the yield of charge separation at PbS/Sn[O.sub.2] interfaces, with a smaller PbS particle radius that has resulted in a higher yield of charge separation.

The formation of various isostructural inorganic-organic hybrid ferroelectric compounds from the aggregation of the [[Pb[I.sub.3]].sub.delta] chains directed organic cations to Kagome-shaped tubular architecture is discussed. The large spontaneous polarizations exhibited by these compounds are also explained.

A combination of photoelectron (PE) spectra and density functional theory studies is conducted to explain the preparation and properties of the pyridyl-lead, [[[Pb.sub.m]-pyridyl].sup.-] (m = 1-4) complexes. These compounds are shown to exhibit a closed-shell electron ground-state structure of the singlet state.

The electronic properties of assemblies of heterostructured nanocrystals are examined and a novel approach is described for doping of nanocrystal solids through the intraparticle charge transfer. Au-PbS core-shell nanostructures are chosen as a model system for studying coupling effects between strongly confined metal and semiconductor phases.

Incomplete cuboidal clusters when reacted with group 14 and 15 metal complexes with [s.sup.2][p.sup.0] electronic configuration resulted in the formation of heterometal incorporated cuboidal clusters. X-ray diffraction studies showed the cuboidal clusters as weak complexes of the cluster tridentate ligand with [EX.sub.3].

Hydrogen transfer from Si-, Ge-, Sn-, and Pb-substituted methane and isobutene to methyl and t-butyl radical sites is investigated. The importance of using small-core pseudo-potentials in obtaining accurate barriers and reaction energies is demonstrated.

The phase instability's role in understanding the piezoelectricity in systems like Pb(Zr, Ti)[O.sub.3] is examined. The results have shown that the phase instability, in contrast with polarization rotation, is responsible for the large piezoelectric properties of systems like Pb(Zr, Ti)[O.sub.3] in the vicinity of the morphotropic phase boundary.

A new heterometallic iodometallate containing Pb and Cu, [[Co[(phen).sub.3]].sub.2][[Pb.sub.3][Cu.sub.6][I.sub.16].[C.sub.2][H.sub.5]OH, is synthesized that displays a novel [Pb.sub.3][I.sub.6][I.sub.16] net structure. The clusters form a BN-type layer, where [Pb.sub.3][I.sub.11] and [Cu.sub.6][I.sub.11] clusters take the place of B and N, and the layers contain cavities in which ethanol molecules are located.

A new, simple, organometallic synthetic technique is described for the preparation of Cu, Pb, or both (co-)doped ZnS nanocrystals without injection of precursors. The technique can be further exploited for the synthesis of other doped, sulfide-based semiconductor materials.

Control of cationic conjugated polymers (CPs) performance in light emitting diodes by choice of counterion was studied. It was found that the performance of CPs as the electron transport layer (ETL) in polymer lead emitting diodes is strongly influenced by the charge compensating ions.

The characterization of PbS colloidal quantum dots has helped in determining the diameter and the shape of the nanocrystals. The extinction coefficients as well as the absorption cross sections for a size series of PbS nanocrystals dispersed in hexane are found to be strongly dependent on the particle size.

Nanosized PbS is fabricated on the Ti[O.sub.2] films and the components of the modified Ti[O.sub.2] films are studied by X-ray diffraction (XRD) and electron probe microanalysis (EPMA). The results have shown that the surface modification with optimum nanosized PbS on Ti[O.sub.2] leads to a performance improvement effectively.

The direct potentiometric detectability of calcium, lead, and silver ions in amounts as low as 300 attomoles at 100 picomolar concentrations without any pre-concentration, analyte recycling, or electrocatalytic signal enhancement. It is a perturbatlion-free method and they place zero-current potentiometry among the most sensitive electrochemical methods available.

The BAC-MP4 methodology is applied to 51 SbL(sub n) molecules, providing calculated heats of formation and associated thermodynamic parameters. These data identify a linear variation in heats of formation with ligand substitution, trends in bond dissociation energies (BDE) with ligand identity and a monotonic decrease in BDE upon successive ligand elimination.

The surface structure of organically capped PbS nanocrystals using synchrotron radiation excited core-level photoelectron spectroscopy is studied. The results indicate that the trioctylphosphine ligands passivate only the surface S sites while oleic acid ligands appear to bind mainly to Pb sites.

The synthesis of new, efficient, visible light active photocatalysts through the incorporation of highly electronegative non-transition metal Pb or Sn ions into the perovskite lattice of Ba(In1/3M1/3M'1/3)O3 (M = Sn, Pb; M' = Nb, Ta) is discussed. A greater photocatalytic activity was observed in Pb-substituted derivatives under visible and ultraviolet-vis irradiations as compared to ternary Ba(In1/2M'1/2)O3 and quaternary Ba(In1/3Sn1/3M'1/3)O3 compounds (M' = Nb, Ta).

The binding of the lead (II) cations to the terpyridine-type subunits of the helical ligand is examined. It is found that it leads to the self-assembly of different polynuclear metallosupramolecular architectures of nanometric size.

The electronic conductivity of PbS and CdTe nanoparticle monolayers was examined voltammetrically by using interdigitated array (IDA) electrodes at the air/water interface. The conductivity of the final interfinger deposits was about two orders of magnitude smaller than that for pure metallic lead, indicating some surface contamination and/or less than perfect crystalline structure.

Pb(super 2+) ion exchange in N-octadecanoyl-L-alanine Langmuir-Blodgett film is investigated by FTIR spectroscopy. The condensation effect of Pb (super 2+) gives rise to significant increase in the hydrogen-bonding interaction between adjacent molecules, so that a complete ion exchange occurs after Pb (super 2+) penetrates into the Langmuir-Blodgett film through structure defects.

The synthesis of nanoparticles with compositions AgSb[Te.sub.2], AgPbSb[Te.sub.3] and Ag[Pb.sub.2]Sb[Te.sub.4] is described using reverse micellar synthesis coupled with a sodium borohydride reduction. The reverse micellar process is simple, convenient, general and extendable to nanoparticles with higher m values, and it is low cost and environmental friendly as well.

A series of electrospray ionization quadrupole time-of-flight (ESI Q-TOF) MS experiments using isotopically labeled L-homocysteine (HcyNO) and H2O was conducted. Results indicate that HcyNO forms the covalent dead-end complex N-thio-sulfoximide with dimethylaminohydrolase (DDAH).