Metal atom synthesis, development

The rapid development of nanotechnology has revolutionized scientific developments in recent decades [1]. The synthesis, characterization, and application of functionalized nanoparticles are currently a very active field of research [2], Due to the size limitation of metal nanoparticles, they show very unique properties, which are called nano-size effect or quantum-size effect , which is different from those of both bulk metals and metal atoms. Such specific properties are usually dominated by the atoms located on the surface. In nanoparticles systems, the number of atoms located on the surface of the particles increases tremendously with decreasing of the particle diameter [3]. 

Using N-terminus modified polylysine, we developed a synthesis for an amphiphilic polychelator, A,a-(DTPA-polylysyl)glutaryl phosphatidyl ethanolamine (DTPA-PL-NGPE). This polychelator was incorporated into the liposomal membrane and micelle core during liposome or micelle preparation. This system sharply increased the number of chelated Gd atoms attached to a single lipid anchor. This increased the number of bound reporter metal atoms per vesicle and decreased the dosage of an administered... 

All the methods used to evaporate metals for atom synthesis were developed originally for the deposition of thin metal films. The more important of these techniques are shown schematically in Fig. la-d. Most of the evaporation devices can be scaled to give amounts of metal ranging from a few milligrams per hour for spectroscopic studies to 1-50 gm/hour for preparative synthetic purposes. Evaporation of metals from heated crucibles, boats, or wires (Fig. la-c) generally gives metal atoms in their ground electronic state. Electronic excitation of atoms is possible when metals are vaporized from arcs, by electron bombardment, or with a laser beam (Fig. Id). The lifetime of the excited states of... 

The development of metal atom vapor technology over the last 15 years has made available to the chemist a new and useful synthetic technique. A number of novel transition metal compounds have been isolated by the method, particularly in the field of organometallic chemistry. However, the use of vaporized metal atoms for the synthesis of metal alkoxides and phenoxides by condensation into the neat alcohol has been only briefly mentioned in the literature.27... 

Another broad class of compounds are the bridged carbene complexes. These compounds contain two identical or two different metal centers with the carbene centers bonded to both of the metal atoms in a bridging relationship. However, these binuclear complexes generally do not show classical carbene reactivity and will therefore not be discussed further, except to mention briefly the special case of the titanium-aluminum complex (3) developed by Tebbe and Grubbs and their coworkers.101 This, and related complexes, has proven to be particularly useful in organic synthesis, although its principal importance is in reactions other than cyclopropanations. 

Scheme 1 represents the synthesis of a linear coordination polymer by use of bischeiating ligands such as rubeanic acid, bis-1,3-diketones, and bis-8-hydroxyquinolines which can be attached simultaneously to metal atoms or ions. Equation 6 describes a recent example of the coordination polymers which is prepared according to Scheme 113). This field of coordination polymers was developed from the large research program in USA during the Second World War in attempts to find thermally stable polymers. The activity in this field has been recently increased in the expecta-...

More recent developments have utilized metal vapor synthesis (method F) involving cocondensation at low temperature of the metal, cyclopentadiene (or other dienes), and PF3. The hydrido-cyclooctadienyl complex [Cr( 5-C8Hn)(PF3)3H] 125) (see Section IX) made in this fashion exhibits variable-temperature NMR spectra which establish the existence of an exchange between the hydrido atom and a methylenic hydrogen bound to an sp3 carbon adjacent to the diene unit. 

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