Spectra metal-free

Optical Spectra. The UV-vis spectrum of pz (219) shows a Soret band at 366 nm and a split Q band at 586 and 656 nm, which is characteristic for metal free porphyrazines. The Ni(II)(pz) (220) shows a Soret band at 343 nm and a single Q band at 613 nm (31). Porphyrazines 219 and 220 undergo a rapid color change from blue to purple upon dinitration in CH2C12. The dinitroporphyrazincs 221 and 222 are somewhat unusual in showing similar absorption spectra with split Soret bands (353 and 373 nm for 221, 348 and 370 for 222) as well as split Q bands (523 and 657 nm for 221, 582 and 659 for 222). 

Fig. 46.6 UV-Vis spectrum of metal-free porphyrazine H2Pz in CHC13...

Fig. 4.7. Field emission spectra of W(112) and W(IOO). Dotted curve theoretical field emission spectrum for free electron metals. Dashed curve experimental field emission spectrum for W(112). Solid curve experimental field emission spectrum for W(IOO), A substantial deviation from the free electron metal behavior is observed. The deviation, so-called Swanson hump, is due to the dominating role of localized surface states near the Fermi level at W(IOO) surface in field emission. (After Swanson and Grouser, 1967).

The singlet (S = 0) state lies about 1000 cm above the ground state triplet (S = 1) in the EPR spectrum of free dioxygen. Transitions associated with triplet oxygen in solution are detectable by EPR at low temperatures, but dioxygen complexes with even electron metal centers (e.g., ferroheme) are not generally observable by this method. Usually, only odd electron systems (Kramers systems) are detectable by magnetic resonance. 

The photoconductivity of organic dyes, especially phthalocyanine pigments, could be utilized to provide reusable or non-reusable electrophotographic plates having sensitivities that extend over the entire visible spectrum and produce high-contrast images 167,168) Microcrystalline dispersions of metal-free phthalocyanine in suitable binders have a white-light sensitivity equal to that of selenium 169> and can be incorporated into coated papers and drums. 

A study of the hyperfine splitting of the e.s.r. spectrum of the cation radical of oxidized zinc(n) bacteriochlorin, together with selective deuteriation, has allowed assignment of the electron density to the atoms of the system.279 There is high spin density on the protons of the saturated rings of the bacteriochlorin with or without the zinc. A similar situation may pertain in metal-free bacteriochlorophyll. 

The lanthanides modify the UV absorption spectra of proteins when aromatic chro-mophores are present at the binding site. Sharp maxima at 245 and 295 nm in the difference spectrum of transferrin saturated with Tb3+ ion as opposed to that of metal free protein were observed [20]. The shape of the spectrum is suggestive of lanthanide induced... 

Fig. 16. Spectroscopic characterization of the oxidized apogalactose oxidase free radical, (a) Optical absorption spectrum for the radical-containing apoprotein, (b) X-band EPR spectrum of the metal-free protein following Ir(IV) oxidation, (c) Expansion of the region near g = 2 comparing experimental data (Exp) with a theoretical simulation (Sim) based on coupling of the unpaired electron spin with one and one Hp proton of a tyrosine phenoxyl. Simulation parameters g = 2.0017, g2 = 2.0073 Ai Ha) = 8.4 G, A2(Hc,) = 8.8 G di(Hp) = 12.7 G, A2(Hp) = 13.8 G.

The absorption due to cysteine residues in proteins is usually more or less obscured by the aromatic residues. With thionein, a cadmium- and zinc-binding protein from equine renal cortex, this is not the case. Its spectrum in both a metal-containing and metal-free form is shown in Fig. 

In the case of the metal-free species 2.256, the electronic absorption spectrum shows characteristic Q-like absorption bands ascribable to both the porphyrin and corrole subunits. In the Soret region, however, the intensity of the porphyrin absorbance overwhelms that of the corrole absorbance. In complex 2.259, only the absorbance bands of the porphyrin are visible, both in the Soret and in the Q-band region. Again, this was rationalised in terms of the much greater absorption intensity of the metalloporphyrin chromophore compared to that of the metallocorrole." ... 

The vibrational spectra of solid saccharin and metal saccharinates have been extensively studied and reviewed <2001COR1059, 2001JST(563)335>. The spectrum of free saccharin exhibits a weak band at 3215 cm due to the N-H vibration this band is not present in the spectra of its sodium salt or of saccharinato complexes. 

The mass spectrum of 156 exhibits peaks due to the series (M — nCO) " (n = 0-4). The base peak in the mass spectrum is due to the metal-free arsole ion . 

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