вход по аккаунту


Luminescence Amplification and Extinction by Electric Fields.

код для вставкиСкачать
The cyclic N- hydroxylaminoacetal of 5-hydroxypentanal(II)
is remarkably stable. On standing for several months at room
temperature no change could be observed. However, on
distillation in Y ~ C U Oa considerable amount (ca. 40%) isornerized to the tautomeric N-oxide of 5-hydroxy-I-(N-methyl-
imino)pentane (111) (b.p. 15O0C/O.3mm.; nL3 = 1.4858). The
structure of (111) was elucidated by analysis and infrared
spectroscopy (C=N: 6.0 p; N + 0: 6.6 p). The physical
data for (111) are in agreement with those of its higher
homologs [3].
[Z 274/104 IEI
Received, May 10th. 1962
[I]E. Bamberger, Ber. dtsch. chem. Ges. 33,941(1900); H. Hellmann and K . Teichmann, Chem. Ber. 89, 1134 (1956).
[2] G. A. Snow, J. chem. SOC. (London) 2588 (1954).
[3] A. A. Sayigh and H . Ulrich, unpublished.
Luminescence Amplification and Extinction
by Electric Fields
H. E. Gumlich, Berlin-Dahlem (Germany) and Newark, Del.
The amplification and extinction of the luminescence of
powdered manganese-activated ZnS- and ZnS-CdS phosphors by electric fields depends on the field strength, field
frequency, intensity and wavelength of the exciting radiation,
the emission wavelength, and the temperature. Of particular
interest are phosphors whose luminescence can also be
amplified by infrared and red light and those in which the
number of radiationless efectronic recombinations is increased
by the additional inclusion of cobalt. An investigation of these
phosphors reveals that the maximum amplification is
produced by infrared and red light of wavelength 1350 and
770 mp, respectively. The field amplification attains a
maximum for field frequency between 10 and 100 cps. If the
exciting radiation, the stimulating light and the electric field
all act simultaneously on these phosphors, then the effect of
the electric field and of the stimulating radiation is not equal
to the sum of the individual effects, i.e. the infrared amplification and the field amplification are not independent of one
another. The nature of the interaction depends on the field
strength, the field frequency and the intensity of the stimulating radiation but not, however, on the cobalt content.
The cobalt content of the phosphor does have a marked
effect on the field amplification. The luminescence amplification in its dependence on the cobalt content passes through
a maximum: low cobalt concentrations cause an amplification
greater than, and high cobalt concentrations cause an amplification smaller than is the case in the absence of cobalt.
With a cobalt addition of 10-6 parts by weight and at low
field frequencies, the electric field can effect an eighteenfold
increase in luminescence. The Iuminescence amplification
observed for powdered phosphors was compared with the
field amplification effects measured in the red bands for CdS
single crystals.
(GDCh-Ortsverband Berlin (Germany), February 20th. 19621
[VB 577122 IE]
The Chemistry of Mercaptoacrylic Acid
K.-D. Gimdermann, Munster (Germany)
Following a survey of a- and p-alkylmercaptoacrylic acid
derivatives [l] a new, generally applicable, method for the
preparation of a,/3-bis[alkylmercapto]acrylicacid derivatives
was presented: Mercaptalization of formylalkylmercapto-
(I) R=H,R'=CH&Hs
acetate fotlowed by removal of one mole of mercaptan from
the mercaptals by means of KHS04 yields esters of a,P-bis[alkylmercapto]acrylic acid.
The easily accessible a,P-bis-[benzylmercapto]acrylic acid (I)
can then be converted to 1,4-dithi-2-ene-2-carboxylic
acid as
well as to the higher melting a$-bis[methylmercapto]acrylic
acid [2] by debenzylation with sodium or lithium in Iiquid
ammonia and subsequent realkylation with 1,Z-dichloroethane or methyl iodide. Thus their steric assignment is
The relatively high dibenzyl formation of up to 50 % of the
theoretical amount, during the reductive debenzylation, also
supports the cis-configuration of both benzylmercapto groups
in (I); this is explained by the spatial proximity of the two
benzylmercapto groups (fixation by the double bond). The
characteristic dimerization tendency of a-alkylmercaptoacrylonitrile and ester is also found with a-alkylmercaptoacroleins; the a-methylmercaptoacrolein synthesized from
thioglycidaldehyde diethylacetal 131 by way of P-diethylamino-a-mercaptopropionaldehydediethyl acetal has. up to
the present time, only been obtained as the semicarbazone of
dimer (11).
The peculiar reactivity of a-alkylmercaptoacrylic acid derivatives is explained by the fact that thioether groups can act as
electron donors as well as acceptors [4].
[GDCh-Ortsverband Ruhr, MiiIheimlRuhr (Germany),
March 28th. 19621
[VB 578/29 IE]
[l] K. D . Gundermann and R . Huchting, Chem. Ber. 95, 632
(1962) and earlier communications.
121 K. D. Gundermannand R. Thomas, Chem. Ber. 91,1330(1958).
[3] J. B. Wright, J. Arner. chem. SOC.79. 1694 (1957).
[4] G. Cilento, Chem. Reviews 60, 147 (1960);H . C. Volger and
J. F. Arens, Rec. trav. chim. Pays-Bas 77, 1170 (1958).
Application of Electron Paramagnetic Resonance
Spectroscopy in Studies on Oxidizing Enzymes
Helmut Beinert, Madison, Wisc. (USA)
Although electron resonances (EPR) spectroscopy has many
potential applications in the study of biological problems.
One of the most serious handicaps of the method is its relative
insensitivity in aqueous media, owing to the strong background absorption of microwave energy by water. Nevertheless, recent experimental work has shown that in problems of
enzyme chemistry, EPR spectroscopy may yield answers which
cannot at present be obtained by other methods. Thus, for
example, a new group of oxidation-reduction catalysts were
discovered in beef heart mitochondria, that can only be recognized by their characteristic EPR signals [I]. Typical asymmetrie signals (g 11 = 2.00, g l = 1.94) are observed even with
samples of freshly frozen whole heart or liver and are also
Angew. Chem. internat. Edit. 1 Vol. I (1962) / No. 6
Без категории
Размер файла
135 Кб
luminescence, amplification, field, electric, extinction
Пожаловаться на содержимое документа