排序方式: 共有19条查询结果,搜索用时 31 毫秒
1.
Dr. Tadas Malinauskas Dr. Maryte Daskeviciene Dr. Giedre Bubniene Ieva Petrikyte Steponas Raisys Dr. Karolis Kazlauskas Dr. Valentas Gaidelis Dr. Vygintas Jankauskas Dr. Robertas Maldzius Prof. Saulius Jursenas Prof. Vytautas Getautis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):15044-15056
Star‐shaped charge‐transporting materials with a triphenylamine (TPA) core and various phenylethenyl side arm(s) were obtained in a one‐step synthetic procedure from commercially available and relatively inexpensive starting materials. Crystallinity, glass‐transition temperature, size of the π‐conjugated system, energy levels, and the way molecules pack in the solid state can be significantly influenced by variation of the structure of these side arm(s). An increase in the number of phenylethenyl side arms was found to hinder intramolecular motions of the TPA core, and thereby provide significant enhancement of the fluorescence quantum yield of the TPA derivatives in solution. On the other hand, a larger number of side arms facilitated exciton migration through the dense side‐arm network formed in the solid state and, thus, considerably reduces fluorescence efficiency by migration‐assisted nonradiative relaxation. This dense network enables charges to move more rapidly through the hole‐transport material layer, which results in very good charge drift mobility (μ up to 0.017 cm2 V ?1 s?1). 相似文献
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Lina Skardžiūtė Karolis Kazlauskas Jelena Dodonova Jonas Bucevičius Sigitas Tumkevičius Saulius Juršėnas 《Tetrahedron》2013
Pyrrolo[2,3-d]pyrimidine derivatives possessing different sterically-hindered end-groups at position 7 of the heterocycle were studied and compared with respect to nanoaggregate formation ability by the reprecipitation method in aqueous solutions. The emergence of nanoaggregates with an increasing water fraction in THF/water mixture was traced by observing sudden changes in spectral and transient fluorescence dynamics accompanied by fluorescence efficiency turn-on. The aggregation induced emission with a maximal 20-fold emission efficiency enhancement was obtained. Tuning of the nanoaggregates sizes from about 50 nm to 600 nm by increasing the THF/water ratio was revealed by electron microscopy. Almost perfect spherical shapes of the nanoaggregates and their structureless fluorescence bands similar to those of their neat amorphous films suggested an amorphous-like nature of the pyrrolo[2,3-d]pyrimidine-based nanoparticles. 相似文献
3.
Kęstutis Arlauskas Arūnas Baronas Nerijus Nekrašas Karolis Kazlauskas 《Journal of Non》2008,354(19-25):2160-2163
Using three electrode vacuum system for glow discharge of 5% SiH4 + 95% Ar gas mixture together with thermal evaporation of phosphorus or boric aced, the n- and p-type a-Si:H layers have been deposited. By co-evaporation of phosphorus or boric aced the conductivity of a-Si:H layers was changed in 10?11–10?3 Ω?1 cm?1 or 10?11 –10?8 Ω?1 cm?1 range, respectively. Blends of a-Si:H and tris-(8-hydroxyquinoline) aluminum (Alq3) have been vacuum-deposited by simultaneous glow discharge of 5% SiH4 + 95 % Ar gas mixture and thermal co-evaporation of Alq3. Photoluminescence spectrum of a-Si:H/Alq3 blend coincident with one of Alq3 was observed at room temperature. 相似文献
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Renata Karpicz Vytautas Getautis Karolis Kazlauskas Saulius Jurnas Vidmantas Gulbinas 《Chemical physics》2008,351(1-3):147-153
Excited state relaxation of indan-1,3-dione derivatives with different substituents attached to the phenyl ring and with the bridged amino group was investigated by means of the steady-state fluorescence and femtosecond time-resolved absorption pump–probe spectroscopy. Bridging of the amino group increases the fluorescence quantum yield and the excited state lifetime. Analysis of the results indicates that the phenyl ring twisting around a single central bond leads to the nonradiative state formation and to subsequent fast relaxation to the ground state. Double bond twisting takes place in molecules with the bridged amino group and causes a large Stokes shift and slightly slower excited state relaxation. 相似文献
6.
Karolis Norvaiša Sophie Maguire Claire Donohoe Dr. John E. O'Brien Dr. Brendan Twamley Dr. Ligia C. Gomes-da-Silva Prof. Dr. Mathias O. Senge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(4):e202103879
Inspired by the rigidified architecture of ‘picket-fence’ systems, we propose a strategy utilizing strain to impose intramolecular tension in already peripherally overcrowded structures leading to selective atropisomeric conversion. Employing this approach, tuneable shape-persistent porphyrin conformations were acquired exhibiting distinctive supramolecular nanostructures based on the orientation of the peripheral groups. The intrinsic assemblies driven by non-covalent bonding interactions form supramolecular polymers while encapsulating small molecules in parallel channels or solvent-accessible voids. The developed molecular strain engineering methodologies combined with synthetic approaches have allowed the introduction of the pivalate units creating a highly strained molecular skeleton. Changes in the absorption spectrum indicated the presence of severe steric repulsions between the peripheral groups which were confirmed by single crystal X-ray analysis. To release the steric strain introduced by the peripheral units, thermal equilibration strategies were used to selectively convert the most abundant atropisomer to the desirable minor one. 相似文献
7.
Sergej Orlov Rusnė Ivaškevičiūtė-Povilauskienė Karolis Mundrys Paulius Kizevičius Ernestas Nacius Domas Jokubauskis Kęstutis Ikamas Alvydas Lisauskas Linas Minkevičius Gintaras Valušis 《Laser \u0026amp; Photonics Reviews》2024,18(5):2301197
The art of light engineering unveils a world of possibilities through the meticulous manipulation of photonic properties such as intensity, phase, and polarization. Precision control over these properties finds application in a variety of fields spanning communications, light–matter interactions, laser direct writing, and imaging. Terahertz (THz) range, nestled between microwaves and infrared light, stands out for its remarkable ability to propagate with minimal losses in numerous dielectric materials and compounds, making THz imaging a powerful tool for noninvasive control and inspection. In this study, a rational framework for the design and optimal assembly of nonparaxial THz imaging systems is established. The research is centered on lensless photonic systems composed solely of high-resistivity silicon-based nonparaxial elements such as the Fresnel zone plate, the Fibonacci lens, the Bessel axicon, and the Airy zone plate, all fabricated using laser ablation technology. Through a comprehensive examination through illumination engineering and scattered light collection from raster-scanned samples in a single-pixel detector scheme, the imaging systems are evaluated via diverse metrics including contrast, resolution, depth of field, and focus. These findings chart an exciting course toward the development of compact and user-friendly THz imaging systems where sensors and optical elements seamlessly integrate into a single chip. 相似文献
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Romas?Baronas Juozas?Kulys Karolis?PetrauskasEmail author Julija?Razumiene 《Journal of mathematical chemistry》2011,49(5):995-1010
This paper presents a two-dimensional-in-space mathematical model of an amperometric biosensor based on an enzyme-loaded carbon
nanotubes layer deposited on a perforated membrane. The developed model is based on non-linear non-stationary reaction-diffusion
equations. By changing input parameters the output results are numerically analysed with a special emphasis to the influence
of the geometry and the catalytic activity of the biosensor to its response. The numerical simulation at transition and steady
state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution
were validated by experimental data. The obtained agreement between the simulation results and experimental data was admissible
at different concentrations of the substrate and the mediator. 相似文献
10.
Leonavicius K Ramanaviciene A Ramanavicius A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(17):10970-10976
A very simple, environmentally friendly, one-step oxidative polymerization route to fabricate polypyrrole (Ppy) nanoparticles of fixed size and morphology was developed and investigated. The herein proposed method is based on the application of sodium dodecyl sulfate and hydrogen peroxide, both easily degradable and cheap materials. The polymerization reaction is performed on 24 h time scale under standard conditions. We monitored a polaronic peak at 465 nm and estimated nanoparticle concentration during various stages of the reaction. Using this data we proposed a mechanism for Ppy nanoparticle formation in accordance with earlier emulsion polymerization mechanisms. Rates of various steps in the polymerization mechanism were accounted for and the resulting particles identified using atomic force microscopy. Application of Ppy nanoparticles prepared by the route presented here seems very promising for biomedical applications where biocompatibility is paramount. In addition, this kind of synthesis could be suitable for the development of solar cells, where very pure and low-cost conducting polymers are required. 相似文献