Wojciech Kuznik

Ferrocene-Donor and 4,5-Dicyanoimidazole-Acceptor Moieties in Charge-Transfer Chromophores with π Linkers Tailored for Second-Order Nonlinear Optics

A series of new nonlinear optical chromophores (1-15) that were comprised of ferrocene-donor and 4,5-dicyanoimidazole-acceptor moieties and various π linkers of different length were synthesized. Support for the presence of significant DA interactions in these NLO-phores was obtained from the evaluation of the quinoid character of the 1,4-phenylene moieties and their electronic absorption spectra, which featured intense high-energy (HE) bands that were accompanied by less-intense low-energy (LE) bands. The redox behavior of these compounds was investigated by cyclic voltammetry (CV) and by rotating-disc voltammetry (RDV); their electrochemical gaps decreased steadily from 2.64 to 2.09 V. In addition to the experimentally obtained data, DFT calculations of their absorption spectra, HOMO/LUMO levels, and second-order polarizabilities (β) (-2ω,ω,ω) were performed. A structure-property relationship study that was performed by systematically altering the π linker revealed that the intramolecular charge-transfer and nonlinear optical properties of these inorganic-organic hybrid D-π-A systems (1-15) were primarily affected by: 1) The presence of olefinic/acetylenic subunits; 2) the length of the π linker; and 3) the spatial arrangement (planarity) of the π linker.

Quantum chemical simulations of solvent influence on UV–vis spectra and orbital shapes of azoderivatives of diphenylpropane-1,3-dione

The DFT modeling of novel synthesized azoderivatives of β-diketones - 2-(2-(2-hydroxyphenyl)hydrazono)-1,3-diphenylpropane-1,3-dione (1), 2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1,3-diphenylpropane-1,3-dione (2), 3-(2-(1,3-dioxo-1,3-diphenylpropan-2-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzene sulfonic acid (3), 2-(2-(1,3-dioxo-1,3-diphenylpropan-2-ylidene)hydrazinyl)benzenesulfonic acid (4), 2-(2-(1,3-dioxo-1,3-diphenylpropan -2-ylidene)hydrazinyl)benzoic acid (5), 2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1-phenylbutane-1,3-dione (6) were performed. The collected information confirms that 1-5 exist in hydrazo form, being stabilized by the intramolecular hydrogen bonds in DMSO solution and solid phase, while 6 exists in mixed enol-azo and hydrazo tautomeric forms, the latter dominating in more polar solvents. The relative stability of various tautomeric and izomeric forms of the symmetric 1-5 and unsymmetric 6 azoderivatives of β-diketones is calculated based on the density functional theory (DFT). Polarizable Continuum Model was used to simulate solvatochromic effects. Solvents of different polarities were used to collect experimental spectra, and the same solvents were chosen for the PCM calculations. The optical properties of 1-6 have been investigated by density functional theory and its electronic absorption bands have been assigned by time-dependent density functional theory (TD-DFT).

Spectral, electrochemical and structural study of aryl derivatives of trans-stilbenes

Aryl-substituted alkenes are promising materials for optoelectronic and photovoltaic applications. In this study we report a new series of stilbene derivatives with aromatic substituents. UV-vis absorption and fluorescence spectra of the studied compounds are presented. The optical properties are found to be dependent on dihedral angle and orbital delocalization between side substituents and the central stilbene moiety, as well as on relaxation of the excited state geometry. Especially the anthracene derivative presents different geometry and excited state properties than other studied compounds. The conclusions are supported by theoretical quantum-chemical analysis at the DFT level. Depending on the type of aromatic side substituents the HOMO orbital is localized either mainly on the central vinylene or the outmost aryl moieties. This affects the reactivity of these compounds in electrochemical reactions as well as the type of oxidation products. The thiophene derivative undergoes polymerization during oxidation and a conjugated polymer is produced while anthracene, phenylene and pentafluorophenylene derivatives undergo irreversible oxidation with creation of unconjugated products.

IR laser induced spectra in novel crystals CdTe–CuInTe2

The novel crystalline alloys CdTe-CuInTe2 were synthesized. The photoinduced spectral changes of the anharmonic phonon modes were explored by cw CO2 laser at power about 2 kW in the vicinity of the 1650 cm(-1) mode. The changes of the intensities for principal phonon modes were found. These modes were assigned both to harmonic as well as anharmonic modes. All the measurements are studied after the Ir illumination. The performed quantum chemical calculations with application of the norm-conserving pseudopotential method and Green functions allow to identify the origin of the content dependent anharmonic phonon modes. Some correlation between the intensities of the corresponding phonon modes at about 1600-1700 cm(-1) and the corresponding IR induced changes were found.

Specific features of Tm3+ doped BiB3O6 glasses fluorescence spectra and their kinetics.

Synthesis and spectral fluorescent features of the thulium-doped BiB(3)O(6) glasses are presented. All spectra were recorded using a pulsed (pulse energy ca. 1μJ, pulse duration 10ns) 355nm third harmonic of 10kHz Nd:YAG laser as an excitation source. A laser beam was focused in a backscattering geometry onto about 1mm(2) spot on the surface of a sample. The Andor SR-303i spectrograph equipped with an Andor DH-501 intensified charge coupled device with spectral resolution up to 1nm was used as a spectra recorder. The time-resolution of this system can be as low as 5ns. The decay kinetics was derived from integrated time-resolved spectra. Additionally the absorption and excitation spectra were measured. The main parameters of the Judd-Ofelt analysis were calculated and comparison of the obtained results with corresponding data for other materials was carried out.

Optical Properties and Quantum-Chemical Calculations of Various Bithienyl Derivatives of Benzene, Triazine and Triphenyltriazine as Organic Light Emitting Diodes

Today, most technologies used to fractionate plant materials are based on expensive chemical processes that often have negative environmental impacts by consuming water, energy, and solvents and creating large quantities of effluents. In addition, during the separation step, the major components are often partially degraded. Achieving high fractionation yields while maintaining the integrity of the macromolecular structure is a major challenge for the next generation of biomass refining processes. Electrostatic separation (ES), which enables the production of enriched fractions in compounds of interest while preserving their (native) functionalities has emerged as an ecofriendly biotechnology for the fractionation of agro-resources in dry conditions. In this review, the potential of ES in a biorefinery scheme is evaluated and the technological obstacles that still need to be overcome for its full deployment at industrial scale are identified.