Роль семьи в процессе первичной социализации в отечественной и зарубежной литературе

A series of 5,15 push–pull <i>meso</i>-diarylzinc­(II) porphyrinates, carrying one or two −COOH or −COOCH₃ acceptor groups and a −OCH₃ or a −N­(CH₃)₂ donor group, show in <i>N</i>,<i>N</i>-dimethylformamide and CHCl₃ solutions a negative and solvent-dependent second-order nonlinear-optical (NLO) response measured by the electric-field-induced second-harmonic generation (EFISH) technique, different from the structurally related zinc­(II) porphyrinate carrying a −N­(CH₃)₂ donor group and a −NO₂ acceptor group, where a still solvent-dependent but positive EFISH second-order response was previously reported. Moreover, when a −N­(CH₃)₂ donor group and a −COOH acceptor group are part of a sterically hindered 2,12 push–pull β-pyrrolic-substituted tetraarylzinc­(II) porphyrinate, the EFISH response is positive and solvent-independent. In order to rationalize these rather intriguing series of observations, EFISH measurements have been integrated by electronic absorption and IR spectroscopic investigations and by density functional theory (DFT) and coupled-perturbed DFT theoretical and ¹H pulsed-gradient spin-echo NMR investigations, which prompt that the significant concentration effects and the strong influence of the solvent nature on the NLO response are originated by a complex whole of different aggregation processes induced by the −COOH group

Tuning the LUMO energy of 1,10-phenanthroline in ??-diimine???dithiolate Ni(II) complex and enhancement of nonlinear optical properties

The synthesis, characterization, nonlinear optical properties and DFT calculations for a new Ni-diiminedithiolate complex [Ni(Cl-4-phen)(mi-5edt)] (Cl-4-phen = 3,4,7,8-tetrachloro-1,10-phenanthroline; mi-5edt = 1-(N-methylindol-5-yl)-ethene-1,2-dithiolate), are reported. The UV-Vis spectrum shows a solvatochromic absorption at 700 nm in DMF (epsilon = 5520 mol(-1) dm(3) cm(-1)) due to a charge-transfer (CT) highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) transition, typical of push-pull complexes. The CT character of this electronic transition is confirmed by DFT calculations with the HOMO mainly centered on the mi-5edt moiety and the LUMO on the Cl-4-phen ligand. By comparison with the unsubstituted analogue compound, computational studies confirm the role of the chlorination enhancing the optical properties of this complex. The second order nonlinear optical properties were measured by EFISH technique (at 1.907 mu m), giving values of -2030 and -810 x 10(-48) esu for mu beta(1.907) and mu beta(0), respectively. These values are among the highest reported so far for the class of d(8) square-planar push-pull compounds

The synthesis and behaviour of pyrazine mononuclear carbonyl complexes of Rh(I), Ir(I), Ru(II) and Os(II)

The synthesis in high yields and the dissociative behaviour in the solid state and in solution of the mononuclear complexes [cis-M(CO)2Cl(pyz)] (M=Rh, Ir; pyz=pyrazine) and [fac-M(CO)3Cl2(pyz)] (M=Ru, Os) are reported. The mononuclear complexes of Rh and Ir are relatively labile with respect to pyrazine release. Particularly in the case of rhodium they generate even in the solid state the corresponding dinuclear complexes [cis-Cl(CO)2M(pyz)cis-M(CO)2Cl] (M=Rh, Ir). The 1H NMR spectra of these mononuclear Rh and Ir complexes in CHCl3 solution show, at 25 and 60 \ub0C, respectively, a fast and reversible dissociation of metal coordinated pyrazine, which is hindered by lowering the temperature. Crystallographic aspects of [cis-Ir(CO)2Cl(pyz)] have been investigated via single crystal X-ray diffraction. The mononuclear complexes of Ru and Os are more stable. In the solid state they do not rearrange, with release of pyrazine, to generate the related dimeric complexes with pyrazine as bridge. In solution, at room temperature, they do not dissociate quickly, although a mixture of monomeric and dimeric pyrazine complexes (ratio monomer to dimer 9:1 and 15:1 for Ru and Os, respectively) is slowly formed by a process which is reverted by addition of excess pyrazine, as expected for a dissociative equilibrium

Les calmars géants

8 páginas, 6 figurasPeer reviewe

Porphyrins for Second Order Nonlinear Optics (NLO): An Intriguing History §

This short review outlines the main results obtained by our research group over the last 15 years in the field of porphyrins and metal porphyrins for second order nonlinear optics (NLO). This overview aims to provide a general framework of the key factors which affect the second order NLO response of porphyrin chromophores. The pivotal role of the porphyrin ring as &pi;-conjugated linker, the nature of the metal center, the substitution pattern which features the geometrical arrangement of donor and acceptor substituents in the different classes of porphyrin NLO-phores, as well as the aggregation phenomena and the role of solvents are addressed in detail

beta-Substituted Zn-II porphyrins as dyes for DSSC: A possible approach to photovoltaic windows

The development of building integrated photovoltaic (BIPV) technology and its implementation in construction of the building envelop provide aesthetical, economical and technical solutions toward the zero-energy building. In this perspective dye-sensitized solar cells (DSSCs), which can be obtained in transparent form and with tunable different colors, offer not only an alternative to the traditional silicon solar cells to be applied in particular to decorative effects on windows and glass integrated façades, but also to indoor structures (and furnishings) in order to recapture the energy spent for the inner lighting, thanks to their peculiar ability of operating in diffuse light condition. In this context, porphyrin-based molecules have an immense potential as light harvesting component of dye-sensitized nanocrystalline TiO2 solar cells, reaching now efficiencies up to about 13%. However the multistep synthesis of the best performing porphyrin dyes, showing a meso substitution pattern, is characterized by very low overall yields compromising their possible applicative development for instance in large photovoltaic (PV) glass modules in competition with the actual commercial PV glass modules based on CuInGaSe2 or CdTe thin voltaic films. In this review the renewed interest in the role of the b-substituted ZnII porphyrins for PV application, less studied than the meso substituted ones, is highlighted. Indeed they can rely on a more accessible synthetic procedure since their tetraaryl porphyrinic core can be easily obtained by a one pot reaction between pyrrole and the appropriate aryl aldehyde. Moreover, their remarkable light harvesting properties in the visible range as well as their peculiar steric hindrance, which strongly opposes to the charge recombination process at the photoanode/dye/electrolyte interface, make this kind of cost-effective porphyrinic dyes more promising for application in new PV glass modules based on DSSC technology, to be applied BIPV

Nonlinear-Optical Properties of α‑Diiminedithiolatonickel(II) Complexes Enhanced by Electron-Withdrawing Carboxyl Groups

We report the synthesis, characterization, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations for three nickel diiminedithiolate complexes [Ni­(4,4′-R₂carboxy-bpy)­(L)] [R = methyl, L = 1,2-benzenedithiolate (bdt), <b>1</b>; R = ethyl, L = 5,6-dihydro-1,4-dithine-2,3-dithiolate (dddt), <b>2</b>; R = ethyl, L = 1-(<i>N</i>-methylindol-5-yl)­ethene-1,2-dithiolate (mi-5edt), <b>3</b>]. The crystal structure of <b>1</b> shows a square-planar coordination for the nickel ion and bond distances consistent with a diiminedithiolate description for the complex. For all complexes, the cyclic voltammetry measurements show two reversible reduction processes (−1.353/–1.380 V and −0798/–0.830 V, respectively) and an anodic wave (+0.372/+0.601 V). The UV–vis spectra present a band around 600–700 nm (ε = 4880–6000 dm³ mol^–1 cm^–1) mainly attributed to a charge-transfer highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) transition, which shows a large negative solvatochromic shift, characteristic of push–pull complexes, and is responsible for the NLO properties of these molecules. The charge-transfer character of this electronic transition is confirmed by DFT calculations, with the HOMO mainly centered on the dithiolate moiety and the LUMO on the bpy ligand, with important contribution given by the carboxyl groups (≈13%). Small contributions from the nickel­(II) ion are present in both of the frontier orbitals. The carboxyl groups enhance the optical properties of this class of complexes, confirmed by comparison with the corresponding unsubstituted compounds. The second-order NLO properties have been measured by an electric-field-induced second-harmonic-generation technique using a 10^–3 M solution in <i>N</i>,<i>N</i>-dimethylformamide and working with a 1.907 μm incident wavelength, giving for μβ_1.907 (μβ₀) values of −1095 (−581), −2760 (−954), and −1650 (−618) × 10^–48 esu for <b>1</b>–<b>3</b>, respectively. These values are among the highest in the class of square-planar push–pull complexes, similar to those found for dithionedithiolate compounds. Moreover, spectroelectrochemical experiments demonstrate the possibility of using these complexes as redox-switchable NLO chromophores

Nonlinear-Optical Properties of α‑Diiminedithiolatonickel(II) Complexes Enhanced by Electron-Withdrawing Carboxyl Groups

We report the synthesis, characterization, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations for three nickel diiminedithiolate complexes [Ni­(4,4′-R₂carboxy-bpy)­(L)] [R = methyl, L = 1,2-benzenedithiolate (bdt), <b>1</b>; R = ethyl, L = 5,6-dihydro-1,4-dithine-2,3-dithiolate (dddt), <b>2</b>; R = ethyl, L = 1-(<i>N</i>-methylindol-5-yl)­ethene-1,2-dithiolate (mi-5edt), <b>3</b>]. The crystal structure of <b>1</b> shows a square-planar coordination for the nickel ion and bond distances consistent with a diiminedithiolate description for the complex. For all complexes, the cyclic voltammetry measurements show two reversible reduction processes (−1.353/–1.380 V and −0798/–0.830 V, respectively) and an anodic wave (+0.372/+0.601 V). The UV–vis spectra present a band around 600–700 nm (ε = 4880–6000 dm³ mol^–1 cm^–1) mainly attributed to a charge-transfer highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) transition, which shows a large negative solvatochromic shift, characteristic of push–pull complexes, and is responsible for the NLO properties of these molecules. The charge-transfer character of this electronic transition is confirmed by DFT calculations, with the HOMO mainly centered on the dithiolate moiety and the LUMO on the bpy ligand, with important contribution given by the carboxyl groups (≈13%). Small contributions from the nickel­(II) ion are present in both of the frontier orbitals. The carboxyl groups enhance the optical properties of this class of complexes, confirmed by comparison with the corresponding unsubstituted compounds. The second-order NLO properties have been measured by an electric-field-induced second-harmonic-generation technique using a 10^–3 M solution in <i>N</i>,<i>N</i>-dimethylformamide and working with a 1.907 μm incident wavelength, giving for μβ_1.907 (μβ₀) values of −1095 (−581), −2760 (−954), and −1650 (−618) × 10^–48 esu for <b>1</b>–<b>3</b>, respectively. These values are among the highest in the class of square-planar push–pull complexes, similar to those found for dithionedithiolate compounds. Moreover, spectroelectrochemical experiments demonstrate the possibility of using these complexes as redox-switchable NLO chromophores