Synthesis and some spectroscopic properties of tetra-2,3-pyridoporphyrazinatosilicon involving bulky axial ligands

2000 ◽  
Vol 04 (05) ◽  
pp. 538-543 ◽  
Author(s):  
TARO NONOMURA ◽  
NAGAO KOBAYASHI ◽  
TATSUYA TOMURA
Keyword(s):  
Thermal Analysis ◽  
Electronic Absorption ◽  
Nmr Spectra ◽  
Electronic Absorption Spectra ◽  
Spectroscopic Properties ◽  
Molecular Orbital Calculations ◽  
Face To Face ◽  
Axial Ligands ◽  
20 Nm ◽  
Thermal Stability Of

Tetra-2,3-pyridoporphyrazinatosilicon ( SiPyD ) containing bis(tri-n-hexylsiloxy) (1) or bis(n-heptylcarbonyloxy) (2) axial ligands have been prepared and characterized by NMR, IR and electronic absorption spectroscopies and by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). These SiPyDs are soluble in common organic solvents, and face-to-face-type stacking is prevented in solution and films. Accordingly, their NMR spectra could be reasonably assigned. Their electronic absorption spectra in solution appear to the blue and red compared with those of the corresponding Si phthalocyanines ( SiPcs ) and Si tetrapyrazinoporphyrazines ( SiPyZs ) respectively. These characteristics are reproduced by molecular orbital calculations in the framework of the Pariser-Parr-Pople approximation. On formation of films, the Q bands shift to the red of those in solution by ca 20 nm, suggesting that other similar tetravalent metallophthalocyanines with two long axial ligands can be used for shifting the Q band to the red. TGA and DTA experiments show that the thermal stability of the macrocycles is markedly influenced by the type of axial ligands.

Electronic structure of low-spin six-coordinate iron(III) meso-tetrapropylchlorin complexes

2014 ◽  
Vol 18 (08n09) ◽  
pp. 778-791 ◽  
Author(s):  
Akira Ikezaki ◽  
Jyunpei Ono ◽  
Yoshiki Ohgo ◽  
Mari Fukagawa ◽  
Takahisa Ikeue ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ground State ◽  
Nmr Spectra ◽  
Spectroscopic Properties ◽  
H Nmr ◽  
Axial Ligands ◽  
Splitting Parameter ◽  
Nmr Signals ◽  
Electronic Ground ◽  
C Nmr

Low-spin iron(III) tetrapropylchlorins [ Fe ( T n PrC ) L 2]± (L = HIm, 1-MeIm, DMAP, CN-, 4-CNPy, tBuNC) adopt the dxy-type ground state regardless of the nature of axial ligands. Among the complexes examined, [ Fe ( T n PrC )( t BuNC )2]+ has shown quite unique spectroscopic properties as described below. (1) 1 H NMR signals were extremely broad as compared with those of other complexes. In particular, 5,20- CH 2(α) signal was too broad to detect. (2) No signals except C γ were observed in 13 C NMR spectra. (3) Tetragonal splitting parameter (|Δ|) estimated by the EPR g values at 4.2 K reached as much as 12.4 λ, which is the largest |Δ| value among all the low-spin iron(III) porphyrins and porphyrinoids reported previously. On the basis of these results, we have concluded that [ Fe ( T n PrC )( t BuNC )2]+ adopts the low-spin iron(III) with (dxz, dyz)4(dxy)1 electronic ground state at 4.2–30 K where the EPR spectra are taken, while it should be expressed as the low-spin Fe ( II ) chlorin π-radical cation [ Fe II ( T n PrC .)( t BuNC )2]+ at ambient temperature where the NMR spectra are taken.

Exciton and electron interaction in covalently-linked dimeric porphyrins

1978 ◽  
Vol 56 (12) ◽  
pp. 1712-1715 ◽  
Author(s):  
John B. Paine III ◽  
David Dolphin ◽  
Martin Gouterman
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Nmr Spectra ◽  
Electronic Absorption Spectra ◽  
Electron Interaction ◽  
Covalently Linked ◽  
C Nmr

The interactions between dimeric porphyrins, covalently linked at their peripheries, have been measured from their electronic absorption spectra and 13C nmr spectra.

The electronic absorption spectra of some N-sulfinylanilines. A molecular orbital treatment

1997 ◽  
Vol 75 (7) ◽  
pp. 934-941 ◽  
Author(s):  
R. Abu-Eittah ◽  
H. Moustafa ◽  
A.M. Al-Omar
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electron Acceptor ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Basis Sets ◽  
Theoretical Treatment ◽  
Molecular Orbital Calculations ◽  
Strong Electron ◽  
Anti Conformer

The electronic absorption spectra of N-sulfinylaniline and some of its derivatives were investigated using different solvents. The spectral behavior of the molecules indicated their planarity and that the NSO group is a strong electron acceptor. All the observed bands correspond to delocalized π → π* transitions; n → π* transition were not observed as discrete bands. Ab initio molecular orbital calculations were performed using four different basis sets. The results showed that the NSO group is nonlinear, the molecules studied are planar, and the syn conformer is more stable than the anti conformer. Keywords: N-sulfinylanilines, spectra and theoretical treatment.

Discotic liquid crystals of transition metal complexes 34: spectroscopic properties of bis[octakis(3,4-dialkoxy-phenoxy)phthalocyaninato]lutetium(III) complexes

2003 ◽  
Vol 07 (02) ◽  
pp. 105-111 ◽  
Author(s):  
Kazuaki Hatsusaka ◽  
Kazuchika Ohta
Keyword(s):  
Thin Film ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Liquid Crystalline ◽  
Electronic Absorption Spectra ◽  
Solvent Polarity ◽  
Spectroscopic Properties ◽  
Temperature Dependent ◽  
First Time ◽  
Hexane Solution

Spectroscopic properties of discotic liquid crystalline bis[octakis(3,4-dialkoxyphenoxy)-phthalocyaninato]lutetium(III) complexes, {[( C n O )2 PhO ]8 Pc }2 Lu (n = 12: 2a and n = 13: 2b), were investigated by recording electronic absorption spectra in the region of 250-2600 nm under three different conditions; solution, mixed solvent solutions, and a thin film at various temperatures. An intermolecular charge transfer (CT) band was found at about 2000-2100 nm both for the n-hexane solution and the thin film. It was established for the first time from the solvent-polarity-dependent and temperature-dependent electronic absorption spectra that the intermolecular CT band is attributable to molecular aggregation.

The Electronic Absorption Spectra of Some N-Substituted Pyrroles—Molecular Orbital Calculations

1982 ◽  
Vol 36 (3) ◽  
pp. 297-301 ◽  
Author(s):  
R. Abu-Eittah ◽  
R. Hilal ◽  
M. S. El-Shall
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Electronic Absorption Spectra ◽  
Experimental Results ◽  
Electronic Transitions ◽  
Molecular Orbital Calculations ◽  
Nonpolar Solvents ◽  
State Functions

The electronic absorption spectra of N-phenylpyrrole and some of its parasubstituted derivatives have been investigated in polar and nonpolar solvents. Such an investigation could predict the extent of resonance interaction between the pyrryl and phenyl moieties of the composite molecule. The direction and polarization of the electronic transitions were predicted. Molecular orbital calculations using the SCF-CI procedures were performed on N-phenylpyrrole and some of its p-substituted derivatives. The state functions and energies were computed. The weight of each configuration was evidence for the direction of the electronic transition. The correspondence between the theoretical and experimental results is satisfactory.

The electronic absorption spectra of some coumarins. A molecular orbital treatment

1985 ◽  
Vol 63 (6) ◽  
pp. 1173-1179 ◽  
Author(s):  
Rafie H. Abu-Eittah ◽  
Bahgat Ali H. El-Tawil
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Transition Energy ◽  
Electronic Absorption Spectra ◽  
Band Intensity ◽  
Molecular Orbital Calculations ◽  
Atomic Orbitals ◽  
Experimental Transition

The electronic absorption spectra of coumarin and its derivatives umbelliferone (6-hydroxycoumarin), esculetin (6,7-dihydroxycoumarin), and scopoletin (6-methoxy-7-hydroxycoumarin) were investigated. The n → π* transition was not observed in the spectrum of coumarin but was observed in the spectra of some of its derivatives. Molecular orbital calculations, using the INDO procedures, were carried out on coumarin and some of its derivatives. The activities of the different sites of the molecules are discussed in terms of the coefficients of the atomic orbitals constituting the HOMO and the LUMO. The correspondence between the calculated and experimental transition energy and band intensity is satisfactory.

Electrochemistry of Acetate-, Carbonate-, Sulfate-, and Dihydrogenphosphate-Bridged Dirhodium(II) Complexes

2003 ◽  
Vol 58 (6) ◽  
pp. 563-570 ◽  
Author(s):  
Ș. Özalp Yaman ◽  
A. M. Önal ◽  
H. Isci
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Relative Energy ◽  
Axial Ligand ◽  
Electrolysis Cell ◽  
Cyclic Voltammograms ◽  
Reduction Potentials ◽  
Axial Ligands ◽  
Constant Potential

Complexes, [Rh2(B-B)4L2]n (B-B = CH3COD2 , L = CH3CN, H2O, Cl-, Br-, SCN-; B-B = CO2-3 , SO2-4 , H2PO4̄, L =H2O, Cl-, Br-, SCN-) were prepared and their cyclic voltammograms (CV) and electronic absorption spectra were measured in solution. The CV of the complexes exhibits a reversible one-electron transfer from a metal-based orbital. Constant potential electrolysis at the oxidation peak potential of [Rh2(O2CCH3)4(NCCH3)2] in acetonitrile yielded [Rh2(O2CCH3)4(NCCH3)2]+, a mixed valent Rh(II)DRh(III) cation complex. The formation of the mixed valent complex was monitored by measuring electronic absorption spectra of the solution in situ during the oxidative electrolysis. The reductive electrolysis of the mixed valent complex solution, in the same electrolysis cell, yielded the original electronic absorption spectrum of the starting complex. The changes in the oxidation and reduction potentials of the complexes with different axial ligands, L = H2O, Cl-, Br-, SCN-, are correlated to the relative energy changes of HOMO and LUMO of the complexes, which indicates the metal-axial ligand σ- and π-bonding interactions. Spectroscopic and CV data indicate that the degree of σ-interaction is Cl- > Br- > SCN-, and that of π-interaction is Br- > SCN- > Cl-.

scholarly journals Electronic Absorption Spectra of Some Triazolopyrimidine Derivatives

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Hussein Moustafa ◽  
M. F. Shibl ◽  
Rifaat Hilal ◽  
Laila I. Ali ◽  
Sheimaa Abdel Halim
Keyword(s):  
Charge Transfer ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Dipole Moments ◽  
Molecular Orbital Calculations ◽  
Transition Energies ◽  
Density Distributions ◽  
Nonpolar Solvents ◽  
Experimental Transition

The electronic absorption spectra of triazolo pyrimidine and some of its derivatives were measured in polar as well as nonpolar solvents. Assignment of the observed transitions is facilitated via molecular orbital calculations. Charge density distributions, dipole moments, and the extent of delocalization of the MOS were used to interpret the observed solvent effects. The observed transitions are assigned as charge transfer (CT), localized, and delocalized according to the contribution of the various configurations in the CI-states. The correspondence between the calculated and experimental transition energies is satisfactory.

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