Strategies for the preparation of compounds of alkali metal anions

Dye, James; Andrews, Charles W.; Mathews, Salima

doi:10.1021/j100593a056

Cited by 55 publications

(18 citation statements)

References 10 publications

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“…The synthesis of single crystal and polycrystalline samples of Na + (C222)Naand other sodides has been described elsewhere 23,27,28 as has the instrumentation for time-resolved luminescence studies with excitation by a doubled YAG laser. 10 The vapor deposition apparatus used to prepare stoichiometric thin films of Na + (C222)Na -(500-2000 Å thick) has been described in detail.…”

Section: Methodsmentioning

confidence: 99%

Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Hendrickson

Pratt

et al. 1997

J. Phys. Chem. A

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The optical properties of the alkalide Na + (cryptand[2.2.2])Naare sensitive to the presence of defect electrons and can be dramatically altered by irradiation with light. Fluorescence intensities decrease markedly at excitation power densities above about 1 mW cm -2 , even though this power level is some 10 7 times lower than that required to affect the absorbance. Partial recovery occurs in powder samples over a period of several minutes at 30-100 K. The enhanced quenching of fluorescence is attributed to the presence of photoproduced trapped electrons. Pronounced changes occur in the optical absorbance spectra of vapordeposited thin films of Na + (cryptand[2.2.2])Nafollowing irradiation by high intensity doubled-and tripled-YAG laser pulses. The effects are attributed to the intermediate formation of a "p-band metal" in which half of the electrons in the ground s 2 state of Naare promoted to the p-level, resulting in a high concentration of electrons trapped at some distance from the parent anion site.

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Section: Methodsmentioning

confidence: 99%

Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Hendrickson

Pratt

et al. 1997

J. Phys. Chem. A

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“…A different procedure and experimental setup were used to obtain the optical reflection spectra of Na + (C222)Na - . Single crystal samples were synthesized by methods described previously, ,,, with crystal growth in a pre-evacuated (10 -5 Torr) glass cell at low temperatures. The primary solvent was methylamine, and the second solvent, used to reduce the solubility, was trimethylamine (ratio = 3:1).…”

Section: Methodsmentioning

confidence: 99%

Optical Absorption and Reflection Spectra of Na⁺(C222)Na^-

et al. 1996

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The optical absorbance from 6000 to 29 000 cm -1 of vapor deposited thin films and dilute solutions of Na + (C222)Na -, as well as the reflectance from 4000 to 25 000 cm -1 of oriented single crystals, were measured. The major common feature is a broad band centered at approximately 15 600 cm -1 (1.94 eV). The film spectra also have a shoulder at 18 900 cm -1 (2.34 eV) and a smaller, broad peak at 24 400 cm -1 (3.03 eV) that are not present in the solution spectra. While the solution peak broadened somewhat and shifted dramatically to lower energy with an increase in temperature, the film peak shifted only slightly because of broadening on the low-energy side, indicative of phonon-assisted excitation. As expected from the anisotropic structure, the features of the reflection spectra at near-normal incidence show major differences for light polarized parallel and perpendicular to the c-axis of single crystals. A Kramers-Kronig analysis of the reflection spectra yields the frequency-dependent optical constants of Na + (C222)Na -: the real and imaginary parts of the dielectric function, the energy loss function, the extinction coefficient, and the absorption coefficient. Comparisons between the calculated and observed absorption spectra indicate that the polycrystalline thin films prepared by codeposition of sodium and cryptand[2.2.2] are partially ordered, with the c-axis perpendicular to the substrate surface.

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“…Since all tools probing unpaired spins are extremely sensitive to impurities, we regarded it desirable to warrant highest purity of the samples possible by designing a special procedure for synthesis along which any contaminations, including grease from joints, will be avoided. Our approach is inspired by a technique developed by James L. Dye for the synthesis of extremely sensitive alkalides and electrides [32][33][34][35] as well as used in "living anionic polymerization" [36] and just for the synthesis of very sensitive substances [37]. Since conventional joints need to be avoided, the glassware is composed by sealing and opened by breaking, which is reflected by calling this mode of operation "break-and-seal" technique.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of the “Break‐and‐Seal” Approach to Fullerides of Complex Cations at the Example of KC₆₀(THF)₅·2THF

Kozhemyakina

Nuß

Jansen

2009

Zeitschrift anorg allge chemie

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The "break-and-seal" method known to be used for synthesis of sensitive compounds (alkalides, electrides and for living anionic polymerization) was applied for the first time for fulleride synthesis providing highest purity of the reaction conditions. A new fulleride KC 60 (THF) 5 ·2THF was prepared in solution by reacting fullerene C 60 with potassium and dibenzo-24-crown-8 in tetrahydrofurane. Single crystals were grown from solution by the modified "temperature difference method", single-crystal X-ray analysis was performed revealing

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Strategies for the preparation of compounds of alkali metal anions

Cited by 55 publications

References 10 publications

Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Optical Absorption and Reflection Spectra of Na⁺(C222)Na^-

Demonstration of the “Break‐and‐Seal” Approach to Fullerides of Complex Cations at the Example of KC₆₀(THF)₅·2THF

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Strategies for the preparation of compounds of alkali metal anions

Cited by 55 publications

References 10 publications

Photolysis of Na+(Cryptand[2.2.2])Na-: Photobleaching of Absorbance and Quenching of Fluorescence

Photolysis of Na+(Cryptand[2.2.2])Na-: Photobleaching of Absorbance and Quenching of Fluorescence

Optical Absorption and Reflection Spectra of Na+(C222)Na-

Demonstration of the “Break‐and‐Seal” Approach to Fullerides of Complex Cations at the Example of KC60(THF)5·2THF

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Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Photolysis of Na⁺(Cryptand[2.2.2])Na^-: Photobleaching of Absorbance and Quenching of Fluorescence

Optical Absorption and Reflection Spectra of Na⁺(C222)Na^-

Demonstration of the “Break‐and‐Seal” Approach to Fullerides of Complex Cations at the Example of KC₆₀(THF)₅·2THF