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1.
Quantum-chemical calculations for series of porphin (H2P) and porphyrazine (H2PA) derivatives whose molecules contain a 3,4-annulated five-membered heteroaromatic ring of pyrrole, furan, and thiophene
as well as 1,2,5-triazole, 1,2,5-oxadiazole, and 1,2,5-thiadiazole have been carried out by the AM1 and INDO/Sm methods (m
means “modified parametrization”). As follows from the unrestricted Hartree-Fock AM1 calculations, the ground state energy
of the a isomer is lower than that of the b isomers for all compounds, the a and b isomers being NH isomers with the additional five-membered ring fused to a pyrrolenine or pyrrole ring, respectively. Condensation
of the five-membered ring for the b isomers of the H2P derivatives is shown to extend the main conjugation path from 18-membered to 21-membered cyclopolyene. However, the 18-membered
cyclopolyene for the a isomers of the H2P derivatives and 16-membered cyclopolyene for both isomers of the H2PA derivatives prove to be isolated from the five-membered ring carrying six π-electrons. Based on INDO/Sm computations of
electronic absorption spectra of the H2P and H2PA derivatives, it is shown that the Qx level of the a isomers is sensitive to the nature of the annulated ring whereas the Qy level is practically not shifted. On the contrary, the Qx level of the b isomers is relatively insensitive to the nature of the annulated ring while the Qy level decreases monotonously in the H2P and H2PA series, being the first excited state level for the majority of the derivatives (X is along the NH-HN axis; Y, perpendicular
to it). The electronic absorption spectra at the border of the visible and near-UV regions are determined mainly by two high-intensity
G → Bx and G → By transitions for the H2P derivatives. However, four intense G → Bx, G → By, G → Nx, and G → Ny transitions are characteristic of the spectra of the H2PA derivatives.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 606–622, September–October, 2008. 相似文献
2.
D. I. Volkovich L. L. Gladkov V. A. Kuzmitsky K. N. Solovyov 《Journal of Applied Spectroscopy》2011,78(2):155-164
Geometric structures and excited electronic states for free bases of bacteriochlorin (H2BC) and tetraazabacteriochlorin (H2TABC) as well as for their magnesium complexes (MgBC and MgTABC), analogs of bacteriopheophytin a (H2BPhea) and bacteriochlorophyll a (MgBPhea), have been calculated by a DFT method and by an INDO/Sm method (the INDO/S method with parameterization modified by the
authors), respectively. The factors responsible for the observed bathochromic shift of the long-wavelength Q
x
(0–0) band of MgBPhea relative to H2BPhea,
\updelta EQx @ - 300 \textc\textm - 1 {{\updelta }}{E_{{Q_x}}} \cong - 300\;{\text{c}}{{\text{m}}^{ - 1}} , have been clarified. Contributions of one- and two-electron interactions to the resulting shift of the Q
x
(0–0) band have been analyzed in detail for the H2BC/MgBC, H2TABC/MgTABC, and porphine (H2P)/Mg porphine (MgP) pairs. It is shown that the bathochromic shift under consideration for the tetrahydro derivatives is
caused by a decrease of the orbital energy gap ε1–ε−1 between the lowest unoccupied and highest occupied molecular orbitals. The variation of δ(ε1–ε−1) is large and amounts to –1660 and –920 cm–1 for the H2BC/MgBC and H2TABC/MgTABC pairs, respectively. The two-electron contributions, both into the energy of electronic configurations and due
to the superposition of the configurations, produce a compensating hypsochromic effect such that the shifts
\updelta EQx {{\updelta }}{E_{{Q_x}}} are –260 and –150 cm–1 for the H2BC/MgBC and H2TABC/MgTABC pairs, respectively. It is also shown that the calculated electronic spectra for the considered molecules agree
quantitatively with the experimental absorption spectra. 相似文献
3.
I. I. Polovinko S. V. Rykhlyuk V. B. Koman I. D. Karbovnyk 《Journal of Applied Spectroscopy》2009,76(1):116-120
We propose a new method for obtaining K2Co
x
Ni1–x
(SO4)2⋅6H2O (x = 0, 0.4, 0.8, 1) crystals, involving the use of the chlorides (CoCl2⋅6H2O and NiCl2⋅6H2O) in an aqueous solution instead of the widely used sulfates. We have studied the transmission spectra of the grown single
crystals in the range λ = 200–900 nm and the IR reflectance spectra in the 2.5–20 μm region. We have observed a change in
the position and intensity of the absorption bands as a function of the composition of the crystals. Based on the Tanabe–Sugano
diagrams, we determined the crystal field splitting (Dq) and its dependence on the nickel concentration.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 126–130, January–February, 2009. 相似文献
4.
D. I. Volkovich V. A. Kuz’mitskii K. N. Solov’ev 《Journal of Applied Spectroscopy》2006,73(2):259-274
Using the restricted and unrestricted Hartree-Fock method (RHF and UHF) with the AM1 Hamiltonian, we have calculated the geometric
structure of the NH-isomers of isobacteriochlorin and its meso-cyano derivative. We have used the CNDO/S method for all the
considered structures to calculate the transitions to excited electronic states. We have analyzed the effect of taking into
account electron correlation on the results of the calculations of the chemical and geometric structure and the electronic
spectra. For the a isomer with the imino hydrogens opposite each other, we obtained a planar structure corresponding to literature x-ray diffraction
data. For the aromatic c isomer and other isomers with the imino hydrogens adjacent to each other, the calculations lead to a substantial nonplanarity
of the macrocycle (defined mainly by the tilt of the pyrrole rings) and also deviation of the NH bond from the plane of the
pyrrole ring. The ground-state energies of the a and c isomers have close values, which generally explains the observed NH tautomerism. We calculated the dipole moments of the
isomers in the ground state and the excited state. The results of the calculation of the characteristics of the excited states
with UHF geometry on the whole seem to be preferred over those with RHF geometry. We show that only for the aromatic c isomer can we describe the electronic absorption spectrum within a four-orbital model.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 232–245, March–April, 2006. 相似文献
5.
N. A. Borisevich A. P. Lugovskii V. A. Povedailo E. E. Tselesh D. L. Yakovlev 《Journal of Applied Spectroscopy》2010,77(3):343-348
Conformations of He-jet-cooled trimethyl[(3-indole)ethoxy]silane (TIES) have been studied using a laser spectroscopy technique
in combination with quantum-chemical computations. Six probable conformers of the molecule were computed, of which only two
conformations were observed. Based on an analysis of fluorescence excitation spectra, fluorescence spectra, shapes of rotational
band contours at the electronic S0–S1 transition of TIES, and theoretical computations, the above conformers were assigned to steric structures. Twisted structures
have the lowest energy due to intramolecular hydrogen bonds C - H ?O < CSi C - H \cdots O <_C^{Si} between hydrogen atoms of methyl groups and an oxygen atom and C–H···π between H and the π-electron cloud of the indole ring. 相似文献
6.
A facile and green synthesis of 1,4-disubstituted-1H-1,2,3-triazoles is reported. The reaction of α-azido ketones and terminal alkynes in the presence of [CuSO4 (H2O)5/sodium ascorbate] in a mixture of H2O/polyethylene glycol 400 as solvent afforded the corresponding 1,4-disubstituted triazoles at ambient temperature with short
reaction times and at high yields. The corresponding α-azido ketones were directly prepared in situ from various substituted styrenes using the oxidant cerium ammonium nitrate
and sodium azide in oxygen-saturated methanol. 相似文献
7.
We have used the PBE/3z, B3LYP/6-31G, B3LYP/6-31G(d), and B3LYP/6-311G(d) methods to study the conformational mobility of
2,3-dihydro-3-O-(1,4-naphthoquinon-2-yl)-2-oxo-1,4-naphthoquinones (1–4). We have shown that more than 99% of these compounds exist as the major tautomeric form, while differences in the structure
of the Q2H (2,3-dihydro-2-oxo-1,4-naphthoquinones) and Q1,4 (1,4-naphthoquinon-2-yl) moieties lead to qualitative differences in the internal rotation potentials of the ethyl substituents
V(θEt−1) and V(θEt−2), and consequently each of compounds 1−4 exists as six different rotameric forms. For diquinone 3, we have calculated the dependences of the frequencies (ν) and intensities (A) of the normal vibrations on the torsional
angles θEt−1 and θEt−2, and also on the changes in the geometry of the ether bond. We have found that the values of ν and A for the bands in the
carbonyl region of the IR spectrum change little on going from one rotameric form to another, and also for the in-plane bends
of the ether bond, and change considerably for the out-of-plane bends of the ether bond. However, for T ≤ 300 K, there is
no qualitative change in the overall contour, and it can be interpreted based on a simple additive model.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 573–581, September–October, 2006. 相似文献
8.
The title compound, C26H24N2O6S, (I), crystallizes in the monoclinic space group, P21/c, with cell parameters a = 16.248(1), b = 7.927(1), c = 19.371(4) ?, β = 105.295(2)°, Z = 4. The central pyrimidine ring in the compound (I) is significantly puckered, assuming a screw-boat conformation. The C11–C16 benzene ring stands vertical while thiazole and
C18–C23 benzene rings are coplanar to the mean plane of pyrimidine ring having dihedral angles of 87.48(12), 3.63(11) and
0.94(12)°, respectively. In the absence of potential hydrogen bonding interaction, the crystal packing is influenced by intramolecular
C-H…S interaction and intermolecular C-H…π interactions. 相似文献
9.
Pierre-Yves Roger Fabien Blondeau David Bensa Thierry Constantieux Jean Rodriguez 《Molecular diversity》2009,13(4):469-473
A new one-pot domino reaction for a general entry to functionalised bridged bicyclo[n.2.1] ring systems from α ,α’-diactivated cyclic ketones and trans-1,4-dihalides is described. The sequence combines a base promoted C–O cycloalkylation reaction leading to fused polycyclic
enol ethers and their in situ palladium-catalysed isomerisation. 相似文献
10.
S. M. Pershin 《Physics of Wave Phenomena》2009,17(4):241-250
A mechanism is proposed for the previously observed [1] jump in erythrocyte fluidity through a microcapillary 1.3 μm in diameter
at a temperature of 36.6±0.3°C. Our interpretation is based on the experimental evidence both for existence of ortho and para
H2O isomers in water and on spin-selective interaction of proteins with para H2O isomers as hydration shells of biomolecules are being formed [2]. It is important that the formation of hydration shells
of proteins and DNA in aqueous solutions is accompanied by an increase in the Brillouin shift to 0.4 cm−1 (≃0.25 cm−1 in water), which points to the formation of icelike structures. We believe that the coincidence of the translational energy
kT of the Brownian motion and the energy of the rotational quanta for the 313–202 transition of para H2O isomers at the temperature 36.6°C increases the probability for excitation of para H2O isomers in collisions. Collisions mix quantum states of closely spaced levels in para H2O (313, 285.2 cm−1) and ortho H2O (330, 285.4 cm−1) and induce conversion of para isomers to ortho H2O. It is assumed that this conversion in the icelike hydration shell of hemoglobin (Hb) is accelerated under the catalyzing
effect of oxygen and iron present in Hb and triggers a chain reaction: release of ortho H2O isomers through the erythrocyte membrane→compaction of Hb molecules and increase in concentration of catalysts→acceleration
of conversion→structural gel-sol transition. It is the sequence of these processes that provides a jump in fluidity of erythrocytes
through a microcapillary and the anomalous increase in fluidity of the aqueous solution of hemoglobin by almost an order of
magnitude at temperatures close to 36.6°C and an increase in the solution concentration by a factor of 1.7. 相似文献
11.
D. V. Berdyshev V. P. Glazunov A. Ya. Yakubovskaya T. Yu. Kochergina V. F. Anufriev 《Journal of Applied Spectroscopy》2006,73(6):798-806
We have used B3LYP/6-31(d) density functional theory to calculate the frequencies and modes of the normal vibrations of 2-oxo-2,3-dihydro-and
2-methoxy-1,4-naphthoquinones. Based on these calculations within an additive model, we have assigned the carbonyl bands in
the IR spectra of 2,3-dihydro-3-O-(1,4-naphthoquinon-2-yl)-2-oxo-1,4-naphthoquinones (diquinones 1–4). We have carried out a direct calculation of the vibrational spectra for diquinones 1–4 using PBE and B3LYP correlation functionals. We have shown that the calculation of the vibrational spectra of the diquinones
based on an additive model on the whole is quite consistent with the results of direct calculations and the experimental spectra.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 713–720, November–December, 2006. 相似文献
12.
Laboratory formation of four isomers of C5H2 molecule is reported and detection of the ring-chain isomer (isomer 1) of C5H2 in cosmic objects has been suggested. For identification of a molecule in cosmic objects, one of the required input data
is EinsteinA-coefficients (radiative transition probabilities) for the molecule. Here, we report EinsteinA-coefficients for electric dipole transitions in the ring-chain isomer of C5H2 among the rotational levels of the ground electronic and ground vibrational states up to 21 cm−1. 相似文献
13.
Spectral-luminescence properties of a norbornene-substituted tetraazachlorin and its metal complexes
M. V. Belkov A. A. Grishchuk S. V. Dudkin E. A. Makarova P. P. Pershukevich K. N. Solovyova 《Journal of Applied Spectroscopy》2010,77(2):213-222
The spectral-luminescence properties of a tetraazachlorin derivative with a norbornene fragment annelated to a reduced pyrrole
ring and its complexes with zinc and palladium have been studied at 293 and 77 K. For the norbornene-substituted free base,
differences in fluorescence from unsubstituted tetraazachlroin and its dibenzobarrelene-substituted analog are found. The
fluorescence lifetime is observed to rise by ∼7 times for the free base and by ∼1.6 ties for the Zn complex on going from
293 to 77 K. An essential dependence of the photophysical parameters on the nature of the solvent is noted. The fluorescence
polarization spectrum of the norbornene-substituted tetraazachlorin reveals in the Soret band region at least four electronic
transitions. For the Pd complex, weak phosphorescence in the near IR region has been detected; the 0–0 band maximum is at
990 nm and the singlet–triplet interval amounts to 5800 cm–1, which is larger by 400 cm–1 than for Pd tetraazaporphine. The quantum yields of the photosensitized formation of singlet oxygen have been determined
using a relative luminescence method. 相似文献
14.
M. V. Belkov G. A. Ksendzova G. I. Polozov I. V. Skornyakov V. L. Sorokin G. B. Tolstorozhev O. I. Shadyro 《Journal of Applied Spectroscopy》2009,76(3):408-413
We have used Fourier transform IR (FTIR) spectroscopy to study intramolecular interactions in solutions of 4,6-di-tert-butyl-2-aminophenol in n-hexane. When the hydroxyl group in the molecule is ortho to the amino group, an O―H⋅⋅⋅N intramolecular hydrogen bond is formed
in the 4-6-di-tert-butyl-2-aminophenol derivatives, where the strength of the hydrogen bond depends on the type of substituent at the para position
of the phenyl ring. If there are electron-donor groups on the phenyl ring, then a stronger O―H⋅⋅⋅N bond is formed in the 4,6-di-tert-butyl-2-aminophenol derivatives than in molecules containing electron-acceptor Cl and Br atoms. Formation of the above-indicated
intramolecular hydrogen bond affects the course of radiation-induced reactions occurring in n-hexane with participation of these compounds and also affects their antiviral activity.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 434–439, May–June, 2009. 相似文献
15.
M. A. Rabbih Kh. A. Sife-Eldeen A. M. Hassan Rezk E. T. M. Selim 《Journal of Applied Spectroscopy》2011,78(1):25-30
Electron ionization mass spectra of N-, 2-, 3-, and 4-cyclohexyl-N-phenylaniline isomers have been obtained and investigated.
Molecular ions of the 2–4 isomers are the base peaks demonstrating their high stability relative to the N-isomer in which
the molecular ion intensity is about 76%. The characteristic primary fragmentation pattern for each isomer is proposed and
discussed. Further fragmentations of some of the primary fragment ions is also discussed. 相似文献
16.
T. Ritschel P. J. Kuntz L. Zülicke 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):93-107
ArnHCl+ van-der-Waals clusters for n = 1–13 are investigated
with the “minimal diatomics-in-molecules (DIM) model”
using ab-initio input data obtained from multi-reference
configuration-interaction calculations plus subsequent projection onto
valence-bond wavefunctions.
The results for the complexes with n = 1–3 are checked against
ab-initio calculations at the
coupled-cluster (CCSD) level with the same one-electron atomic basis set as
for the input data generation (aug-cc-pVTZ from Dunning).
In addition to the electronic ground state,
the first excited
2A¢^2\!A^{\prime}
state for the triatomic
complex (n = 1) is also studied.
The results
from the DIM model are shown to be in fair agreement with those from
advanced conventional ab-initio calculations, although there are
differences in detail. The comparison
justifies the extension of the DIM approach to n > 3.
Systematic analysis of the local minima of the multi-dimensional
potential-energy surfaces (PESs), carried out with the combined
method
described in part I (Monte-Carlo sampling plus subsequent steepest-descent
optimization), reveals simple building-up regularities for the most
stable structures (i.e. those corresponding to the global PES minimum)
at each n: apart from always having a nearly linear
(Ar–H–Cl)+ fragment as core, the aggregates show little
or no symmetry. Secondary local minima are also determined and their
structures interpreted.
The PESs for the low-lying excited states reveal a much more complicated
topography compared to the ArnH+ clusters allowing a variety
of photo-processes.
The energy level sequence of the first five excited electronic states
and the stability of the clusters in these states is studied
as a function of the cluster size n. 相似文献
17.
18.
The electronic structure of La1–x
Ga
x
MnO3+δ. solid solutions is studied by X-ray photoelectron spectroscopy (XPS). The valence state of the manganese is estimated by
various methods: by analyzing the difference in the binding energies of the Mn2p3/2 and O1s electronic levels, analyzing exchange splitting in the spectrum of Mn3s, and from the dependence of the binding energy
of the XPS spectrum of Mn2p3/2 on the calcium concentration. The state of oxidation of the manganese in the compositions containing calcium lies between
Mn3+ and Mn4+. The efficacies of these methods are compared. A correlation is found between the type of crystalline structure of La1–x
Ga
x
MnO3+δ. (0 ≤ x < 1) and the binding energy of the Mn2p3/2 peak.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 419–427, May–June, 2009. 相似文献
19.
Excited singlet (S
1) and triplet (T
1) state quenching by O2 and by (O2 + H2O) gas-vapor mixtures was studied in the gas phase for polycyclic aromatic hydrocarbons (PAHs, anthracene, 2-aminoanthracene,
pyrene). Addition of water vapor is shown not to influence quenching of both fluorescence and delayed fluorescence of PAHs
by oxygen. The role of complexes stabilized by charge transfer and hydrogen bonds in quenching the excited states of PAHs
by atmospheric gases was analyzed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 342–348, May–June, 2009. 相似文献
20.
The solution and solid state conformation of (S)-4,5,6,7-tetrahydro-5-methylimidazo [4,5,1-jk][1,4]-benzodiazepin-2(1H)-one (R78362) have been investigated by low temperature NMR and x-ray diffraction studies. The 1H NMR spectrum of R78362 shows no evidence of the presence of multiple conformers in the temperature range 340K - 177K. Molecular mechanisms and semiempirical molecular orbital calculations suggest that the nitrogen and ring inversion barriers of R78362 are small and thus a time-averaged 1H NMR spectrum is probably occurring at 298K. The x-ray diffraction data indicated that there were two independent molecules in the asymmetric unit of the crystal. The two molecules had similar conformations with the benzoimidazole ring being planar and the diazepine ring in a “half-chair” conformation. 相似文献