Synthesis of tetraphenylporphines with active groups in the phenyl rings. 5. Tetra(carboxymethylenoxyphenyl)porphines and their ethyl esters

Tetra(carboxymethylenoxyphenyl)porphines which are soluble in bases are prepared by hydrolysis of the ethyl esters of tetra(carboxymethylenoxyphenyl)porphines. The starting ethyl esters of the tetra(carboxymethylenoxyphenyl)porphines were synthesized by alkylation of tetra(oxyphenyl)porphines with ethylchloroacetate, as well as by condensation of pyrrole with ethyl esters of formylphenoxyacetic acids.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1373–1377, October, 1989.     

Spectral,Acid, and Coordination Properties of Dodecasubstituted Porphyrins

Russian Journal of General Chemistry - The results of investigation of the interrelation between the geometric structure and coordination, acid, and spectral properties of a series of porphyrins...     

Optical spectra in the region of exciton resonances in quantum wells and quantum dots of In0.3Ga0.7As/GaAs heterostructures

The transparency, reflection and luminescence spectra of In_0.3Ga_0.7As structures with 8 nm thickness and quantum wells limited by the barrier layer GaAs of a 9 nm (upper layer) and 100 nm (bottom layer) thickness had been studied in the region of photon energy 0.5–1.6 eV. Lines associated with the transitions hh,lh1-e1(1s,2s,3s), hh2,lh2-e2(1s,2s,3s), hh1,lh1-e2(1s) and hh3,lh3-e3(1s) had been revealed in reflection spectra. The shapes of the reflection and transparency lines had been calculated using a single oscillator model of dispersion relations and the Kramers–Kronig integrals. The binding energy of hh,lh1-e1 excitons, the effective mass m_hh^∗ and m_lh^∗ and the damping factor for the optical transitions to QW and QD had been determined. The lifetime of charge carriers on quantum dots varies in the range of 0.04–0.1 ps, while the radiative lifetime of excitons in quantum wells in the considered structure is around 2 ps.     

Mesogenic 4-acryloyloxy- and 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates

Procedures were developed which made it possible to synthesize in good yields homologs of 4-acryloyloxyphenyl 4-alkoxybenzoates (C₃, C₅, C₇, C₈) and of 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates (C₅, C₇). The substituted phenylbenzoates obtained exhibit the enantiotropic nematic mesomorphism in a sufficiently wide temperature range. The studied compounds have absorption maxima in the near UV region and a high temperature of decomposition beginning.     

Complex formation of tetra(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butylphenyl)porphine with copper(II) and zinc(II) acetates in organic solvents

The effect of accumulation of the tert-butyl groups in the phenyl rings of tetraphenylporphine on the complex formation rate of tetra(3,5-di-tert-butylphenyl)porphine (I) with copper(II), zinc(II), and cadmium(II) acetates in acetic acid and in a mixed ethanol-benzene solvent was studied by the chemical kinetics method with spectrophotometric monitoring. The activation characteristics of the complex formation were calculated. The complex with zinc was found to form three times more slowly that the copper complex. Benzene additives to the organic solvent decreased the reaction rate because of steric hindrance created by the benzene molecules that formed stable solvates with compound I.     

Phenyl-substituted porphyrins: III. Relative reactivity in the nitration reaction

Study on the nitration of phenyl-substituted porphyrins showed that protonation of the porphyrin macroring does not affect the relative reactivity of the meso- and β-positions and phenyl groups.     

MOVPE-grown high CW power InGaAs/InGaAsP/InGaP diode lasers

Al-free InGaAs/InGaAsP/InGaP laser structures grown by MOVPE have yielded new records in performance. CW front-facet-emitted powers of 5.8 W are achieved from optimized double-quantum-well lasers with 100 μm wide stripes and 1 mm long cavity lengths. Devices with a 0.5 mm cavity length exhibit total power conversion efficiencies as high as 59%. A novel facet passivation technique, consisting of laser-assisted deposition of ZnSe, is shown to increase the COD level by 50%. Single-mode, CW output powers of 400 mW are obtained from triple-core ARROW lasers fabricated by a two-step MOVPE growth process.     

Infrared Lattice Vibrations of TI3AsS4

Infrared reflectivity spectra of TI₃AsS₄ single crystals are measured at room temperature in the wavenumber range from 30 to 4000 cm⁻¹ for the polarization directions E ‖ c and E ‖ a. An analysis of the spectra with the Kramers-Kronig method reveals 10 infrared active modes for each of the polarization directions. On the basis of theoretical estimates the modes due to TI-S and As–S bond vibrations are identified.     

Optical Phonons and Chemical Bonding in TlSbS2, TlSbSe2, and Tl3SbS3 Crystals

The optical phonons at k = 0 of TlSbS₂, TlSbSe₂, and Tl₃SbS₃ have been investigated by infrared reflectivity measurements from 50 to 4000 cm⁻¹ at 300 K. The factor group analysis of vibrational modes of TlSbS₂ and Tl₃SbS₃ crystal lattices has been made. The dielectric constant dispersion for E ‖ a and E ‖ b has been determined by classical dispersion relations. The Szigeti effective charges, the Born dynamic effective charge, and the Tl, Sb, S (Se) relative ion charges were calculated in dependence on the polarization of the incident light.     

Vibrational properties of CdGa2S4

Polarization-dependent infrared reflectivity spectra of CdGa₂S₄ are measured at 300 K in the wavenumber range from 180 to 500 cm⁻¹. The analysis of the spectra yields three E and four B modes in this frequency range. The results are compared with previously published data and a final identification of the infrared active modes in CdGa₂S₄ is proposed. It is shown that the two-phonon absorption spectra of CdGa₂S₄ can be interpreted in terms of zone-centre two-phonon combination modes. The relation between the lattice vibrational properties of chalcopyrite and defect-chalcopyrite compounds is discussed.