Spectroscopic and Thermochemical Information on the O2−O2 Collisional Complex Inferred From Atmospheric Uv/Visible O4 Absorption Band Profile Measurements

2003 ◽  
pp. 273-284
Author(s):  
Klaus Pfeilsticker ◽  
H. Bösch ◽  
R. Fitzenberger ◽  
Claude Camy-Peyret
Keyword(s):  
Absorption Band ◽  
Band Profile ◽  
Uv Visible ◽  
Collisional Complex

Absorption Band Profile of the Origin Region of the b Polarized 4000 Å Anthracene Crystal Transition

1971 ◽  
Vol 55 (12) ◽  
pp. 5610-5621 ◽  
Author(s):  
G. C. Morris ◽  
S. A. Rice ◽  
M. G. Sceats ◽  
A. E. Martin
Keyword(s):  
Absorption Band ◽  
Crystal Transition ◽  
Origin Region ◽  
Band Profile ◽  
Anthracene Crystal

scholarly journals Characterization of Cu(II)-ACC Complexes and Conversion of the Bound ACC into Ethylene in the Presence of Hydrogen Peroxide. Detection of a Brown Intermediate at Low Temperature

2007 ◽  
Vol 2007 ◽  
pp. 1-9 ◽  
Author(s):  
Wadih Ghattas ◽  
Michel Giorgi ◽  
Christian Gaudin ◽  
Antal Rockenbauer ◽  
Marius Réglier ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Low Temperature ◽  
Absorption Band ◽  
Acc Oxidase ◽  
Optimum Activity ◽  
Hydrogen Peroxide Detection ◽  
Crystallographic Structures ◽  
Uv Visible ◽  
Reaction In Water

Two copper(II)-ACC complexes were prepared and characterized: [Cu(bpy)(ACC)(H2O)]⋅CO4(1) and[Cu(ACC)2]3⋅4H2O(2). Their crystallographic structures are described and analyzed. Spectroscopic characterizations (UV-visible and EPR) confirm that the structure is maintained in solution. These complexes are able to produce ethylene in the presence of hydrogen peroxide in an “ACC Oxidase-like” reaction in water and in methanol. The conversion of ACC into ethylene depends on the amount of base, and, in methanol, 3 equivalents of NaOH are needed for optimum activity. The base is proposed to play a role inH2O2deprotonation. The presence of an exogenic ligand (bpy) is important for the reactivity and may stabilize a reaction intermediate. Indeed, a brown intermediate with an absorption band centered at 433 nm can be detected at low temperature when1is treated with 10 equivalents ofH2O2.

Solvent effects on the electronic and vibrational properties of high-valent oxomolybdenum(V) 5,10,15-triphenylcorrole probed by UV-visible and resonance Raman spectroscopy

2009 ◽  
Vol 13 (10) ◽  
pp. 1040-1052 ◽  
Author(s):  
Vicky V. Mody ◽  
Marzena B. Fitzpatrick ◽  
Samantha S. Zabaneh ◽  
Roman S. Czernuszewicz ◽  
Michał Gałęzowski ◽  
...  
Keyword(s):  
Absorption Band ◽  
Linear Correlation ◽  
Triple Bond ◽  
Isotope Labeling ◽  
Resonance Raman ◽  
Index Formula ◽  
Electronic Transitions ◽  
Uv Visible ◽  
High Valent ◽  
Soret Absorption

Solution UV-visible electronic absorption and resonance Raman (RR) scattering spectra in 25 aprotic organic solvents have been measured and analyzed for a high-valent molybdenum( V ) oxo complex of 5,10,15-triphenylcorrole, (MoVO)CorPh3 . Optical absorption data in the visible region show a significant positive solvatochromism upon increasing solvent polarizability (ca. 660 cm-1 for the violet Soret band on going from acetonitrile to carbon disulfide), described by an excellent linear correlation between the bathochromic shifts of corrole π → π* electronic transitions and the solvent refractive index [Formula: see text]. Isotope labeling of the terminal oxo group with 18 O revealed the oxo-Mo(V) stretch of (MoVO)CorPh3 to vibrate at frequency ν(MoVO) ≈ 970 cm-1 [Δ(16O-18O) = 46 cm-1] , consistent with a MoV≡O triple bond. This vibration is greatly enhanced in the RR spectra with excitations within the Soret absorption band and its frequency is sensitive to solute-solvent interactions that weaken the MoV≡O triple bond by inhibiting O2- → Mo5+ electron donation. The ν(MoVO) frequency decreases in direct proportion to the Swain's solvent polarity parameter (A + B), from 969.4 cm-1 in n-hexane solution down to 955.6 cm-1 in dimethyl sulfoxide solution. However, only weak linear correlation was found when the ν(MoVO) frequencies were plotted as a function of the Gutmann's solvent acceptor numbers (ANs). A molecular association occurs between chloroform and (MoVO)CorPh3 through MoV≡O⋯H-CCl3 hydrogen-bonding interactions, manifested as an upshift of the ν(MoVO) RR band in deuteriochloroform solution. The ν(MoVO) stretching frequencies of (MoVO)CorPh3 and its fluorinated derivative (MoVO)Cor(Ph(CF3)2)3 {Cor(Ph(CF3)2)3 = 5,10,15-tris-[3,5-bis(trifluoromethyl)phenyl]corrole} are compared, and the increased strength of the MoV≡O bond in the latter oxo-Mo(V) species is attributed to the cis effect of the electron-withdrawing -C6H3(CF3)2 groups, as judged by a 6 cm-1 elevation of the ν(MoVO) frequency. Raman excitation profiles of ν(MoVO) and corrole skeletal vibrations show the presence of charge-transfer and π → π* electronic transitions within the Soret absorption band of oxomolybdenum( V ) corroles.

UV-Visible and Inelastic Electron Tunneling Spectroscopies of Brevetoxins

1998 ◽  
Vol 52 (4) ◽  
pp. 523-527 ◽  
Author(s):  
J.-L. Brousseau ◽  
N. Vibet ◽  
R. M. Leblanc ◽  
K. S. Rein ◽  
D. G. Baden
Keyword(s):  
Absorption Band ◽  
Electron Tunneling ◽  
Side Chain ◽  
Inelastic Electron ◽  
Double Bonds ◽  
Inelastic Electron Tunneling Spectroscopy ◽  
Vibrational Bands ◽  
Uv Visible ◽  
Inelastic Electron Tunneling ◽  
Electron Tunneling Spectroscopy

We have studied the UV-vis and vibrational spectra of the brevetoxins PbTx-2, PbTx-3, PbTx-9, and 2, 3, 27, 28, 41, 43-hexahydro-(reduced) PbTx-3. The absorption at 194 nm (ε ≈ 18 000 L mol−1 cm−1) of PbTx-2 and PbTx-3 is assigned to the Π–Π* transition of the lactone conjugated double bonds. The n-Π* transition of the lactone is seen at 239 nm (∈ ≈ 2 800 L mol−1 cm−1). The absorption band at 208 nm for PbTx-2 is assigned to the conjugated double bonds of the aldehyde function located on the K-ring side chain. The inelastic electron tunneling spectra of PbTx-2, PbTx-3, PbTx-9, and fully reduced PbTx-3 are presented and the vibrational bands are assigned. We show that inelastic electron tunneling spectroscopy can be used to monitor and measure the vibrational fingerprint of the brevetoxins at a level as low as 1 ng.

The tetratriptycenoporphyrazines revisited

2013 ◽  
Vol 17 (08n09) ◽  
pp. 778-784 ◽  
Author(s):  
Sabeeha Mughal ◽  
C. Grazia Bezzu ◽  
Emma Carter ◽  
Simon J.A. Pope ◽  
Neil B. McKeown
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Absorption Band ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Unique Property ◽  
Resonance Spectroscopy ◽  
Dimer Formation ◽  
Paramagnetic Resonance ◽  
Uv Visible ◽  
Electron Paramagnetic ◽  
Spectroscopic Behavior

The spectroscopic behavior of octa-t-butyltetra-2,3-triptycenotetraazaporphyrin and some of its metal complexes ( Cu 2+, Zn 2+ and Co 2+) were examined. UV-visible and electron paramagnetic resonance spectroscopy indicate that these phthalocyanine derivatives form cofacial dimers in pentane solution. Modeling suggests that the lowest energy configuration of the dimer is a self-complementary embrace in which the two phthalocyanine cores are staggered at an angle of 45° relative to each other. This configuration results in a remarkably intense and sharp absorption band (~635 nm; ε = ~4.0 × 105 M-1.cm-1) arising from excitonic coupling within the dimer, a unique property for self-assembled dimers but analogous to the behavior of certain μ-oxo-dimers of silicon phthalocyanine. Introduction of methyl substituents into the bridgehead positions of the triptycene subunits prevents dimer formation.

scholarly journals SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL STUDIES OF NI (II) COMPLEXES WITH SCHIFF BASE CO-LIGAND DERIVED FROM 5,6-DIAMINO-1,10-PHENANTHROLINE AND BENZENE-1,4-DICARBALDEHYDE

2020 ◽  
Vol 4 (3) ◽  
pp. 132-141
Author(s):  
M. I. Idris ◽  
A. H. Sadi ◽  
A. A. Abubakar
Keyword(s):  
Schiff Base ◽  
Absorption Band ◽  
Inhibition Zone ◽  
Antimicrobial Activities ◽  
Diffusion Method ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Biological Studies ◽  
Coordinate Bond ◽  
Uv Visible

The Schiff base (PDB) was synthesized by refluxing ethanolic solution of 5,6-diamino-1,10-phenanthroline with Benzene-1,4-dicarbaldehyde for 3 hours. Similarly the complexes were synthesized by refluxing equimolar solution of PDB with [Ni(phen)2Cl2] and [Ni(bpy)2Cl2] for 5 hours each and characterized by FTIR, UV-visible, Mass and Elemental Analysis. The absorption band in IR spectrum of PDB at 1593 cm-1 was assigned to C=N stretching frequency which was shifted to 1550 cm-1 and 1549 cm-1 in the spectra of [Ni(phen)2PDB](PF6)2 and [Ni(bpy)2PDB](PF6)2 respectively. The new absorption bands at 721 cm-1 and 754 cm-1 in the spectra of both complexes were due to M-N coordinate bond. The UV- visible absorption band at 390 nm was due to p®p* transitions for azomethine. The low energy band at 450 nm for both complexes is due to MLCT Ni(dp) ®PDB(p*) transition. The molecular ion peak (M)+ in the mass spectra for PDB and the complexes were observed at 443 m/z, 984.75 m/z and 940.95 m/z respectively. The compounds were evaluated for antimicrobial activities, by well diffusion method against bacteria using agar nutrient as the medium and fungi using potato dextrose agar as medium. The free Schiff base has low activity compared to the complexes with inhibition zone between 4.0 mm to 6.6 mm whereas the complexes ranges from 7.5 mm to 11.2 mm.

Spectral and photochromic properties of two long-chain spiropyranindoline monolayers at the air–solid interface

1980 ◽  
Vol 58 (19) ◽  
pp. 2038-2043 ◽  
Author(s):  
Marcel Morin ◽  
Roger M. Leblanc ◽  
Ilona Gruda
Keyword(s):  
Absorption Band ◽  
Surface Pressure ◽  
Spectroscopic Properties ◽  
Photochromic Properties ◽  
Solid Interface ◽  
Pressure Area ◽  
Solid Film ◽  
Uv Visible ◽  
Long Chain

Some long-chain spiropyranindolines have been studied at the air–water and the air–solid interfaces. We have measured the surface pressure–area isotherms of these compounds and two of them are characterized by a solid film. We have also investigated the spectroscopic properties (uv–visible) of these spiropyranindolines in monolayer and in solution. The deposition of monolayers on quartz slides allowed the study of the photochromic properties of these compounds at the air–solid interface. The 3′,3′-dimethyl-1′-hexadecyl-6-nitrospiro(2H-1-benzopyran-2,2′-indoline), irradiated at 253.7 nm, showed the appearance of a new absorption band at 570 nm which varied in intensity when the number of monolayers and the time of irradiation were changed.

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