• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1391-1396
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• 2014

In the present study, ten metal free non-linear optical (NLO) compounds have been designed. These compounds have designed by structural modification of (2-cyano-5-(4-(phenyl(4-vinylphenyl)amino)phenyl) penta-2,4-dienoic acid (TC4). Density functional theory was used for structure optimization and determination of photo-physical properties. These compounds contain triphenylamine as electron-donor and cyanoacrylic acid as acceptor. Five ${\pi}$-spacers are used to connect the donor and acceptor. Two auxiliary donors are also used to assist the donor. Results of this study indicate that stronger electron-donating auxiliary groups and longer ${\pi}$-conjugation enhance NLO response. Major absorption peaks of all systems were in the visible region. These absorption peaks are associated with the ${\pi}-{\pi}^*$ transitions of the entire molecule. From calculations it is clear that all system will be good NLO material. The present calculations will provide new ways for experimentalists to synthesize high-performance NLO material.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3052-3058
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• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1900-1906
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• 2012

Three carbazole chromophores featuring dicyano, cyano, ethyl acetate and dimethyl acetate groups as an acceptor moiety with a ${\pi}$-conjugated spacer and $N$-methyl dibenzo[$b$]pyrole as donor were synthesized by Knovenagel condensation and characterized by IR, $^1HNMR$, $^{13}CNMR$, UV-vis, fluorescence spectroscopy, electrochemistry and theoretical B3LYP/6-$311G^*$ level whilst NLO properties and spectroscopic quantities were calculated. Calculations showed remarkable trend with HOMO located on the donor moiety and LUMO on the acceptors dicyano methylene, cyano, ethyl acetate methylene and dimethyl acetate methylene. In agreement with the calculations, solvatochromic, behavior intramolecular charge transfer band was observed in the visible region.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2010.03a
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• pp.40-40
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• 2010

Studies on attractive color changing property of dye chromophore and fluorophore have been greatly enjoyed in the related industrial and research fields such as optoelectronics, chemosensor, biosensor and so on. The optical property based on D-$\Pi$-A intramolecular charge transfer (ICT) system of chromophore molecules can be utilized as suitable sensing probes for checking media polarity and determining colorimetric chemosensing effect, especially heavy metal detection. These finding are obtained by absorption and emission properties. In this work, donor-acceptor D-$\Pi$-A type fluorescent dyes were designed and synthesized with the corresponding donor and acceptor groups. The selected donor moieties might be provided prominent amorphous properties which are very useful in designing and synthesizing functional polymers and in fabricating devices. Another reasons to choose are commercial availabilities in high purity and low price. Donor-bridge-acceptor (D-A) type dyes can produce impressive optical-physical properties, yielding them potentially suitable for applications in the synthesis of small functional organic molecules. Small organic functional molecules have unique advantages, such as better solubility, amorphous character, and represent an area of research which needs to be explored and developed. Currently, their applications in metalorganic compounds is rapidly expanding and becoming widespread in self-assembly processes, photoluminescence applications, chiral organocatalysts, and ingrafts with nanomaterials. Colloidal nanoparticles have received great attentions in recent years. The photophysical properties of nanoparticles, particularly in terms of brightness, photostability, emission color purity and broad adsorption range, are very attractive functions in many applications. To our knowledge background, colloidal nanoparticles have been enjoyed their applications in bio-probe research fields. This research interest can be raised by the advantages of the materials such as high photoluminescence quantum yields, sharp emission band, long-term photostability and broad excitation spectra. In recent, the uses of nanoparticles being embedded in a polymer matrix and binded on polymer surface have been explored and their properties such as photo-activation and strong photoluminescence have been proposed. The prepared chromophores and nanoparticles were investigated with absorption and emission properties, solvatochromic behaviors, pH induced color switching effects, chemosensing effects and HOMO/LUMO energy potentials with computer simulation. In addition, synthesized fluorophore dyes and particles were applied onto PE/Aramid fiber fluorescing colorations. And the related details were then discussed.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1485-1490
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• 2014

We have designed and developed a new ladder type tetrafused ${\pi}$-conjugated building block such as dihydroindolo[3,2-b]indole (DINI) and investigated its role as an electron rich unit. The photovoltaic properties of a new semiconducting ${\pi}$-conjugated polymer, poly[[5,10-bisoctyl-5,10-dihydroindolo[3,2-b]indole-[5,6- bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole]], represented by PDINI-OBTC8 are described. The new polymer PDINI-OBTC8 was synthesized in donor-acceptor (D-A) fashion, where fused ${\pi}$-conjugated tetracyclic DINI, and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl) benzo[c][1,2,5]thiadiazole (OBTC8) were employed as electron rich (donor) and electron deficient (acceptor) moieties, respectively. The conventional bulk heterojunction (BHJ) device structure ITO/PEDOT:PSS/PDINI-OBTC8:PCB71M/LiF/Al was utilized to fabricate polymer solar cells (PSCs), which comprises the blend of PDINI-OBTC8 and [6,6]-phenyl-$C_{71}$-butyric acid methyl ester ($PC_{71}BM$) in BHJ network. A BHJ PSC that contain PDINI-OBTC8 delivered power conversion efficiency (PCE) value of 1.68% with 1 vol% of 1,8-diidooctane (DIO) under the illumination of A.M 1.5G 100 $mW/cm^2$.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2148-2154
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• 2013

Three push-pull organic semiconductors, TPA-$Th_3$-MMN (1), TPA-ThTT-MMN (2), and TPA-ThDTT-MMN (3), comprising a triphenylamine donor and a methylene malononitrile acceptor linked by various ${\pi}$-conjugated thiophene units were synthesized, and the effects of the ${\pi}$-conjugated bridging unit on the photovoltaic characteristics of solution-processed small-molecule organic solar cells based on these semiconductors were investigated. Planar bridging units with extended ${\pi}$-conjugation effectively facilitated intermolecular ${\pi}-{\pi}$ packing interactions in the solid state, resulting in enhanced $J_{sc}$ values of the SMOSCs fabricated with bulk heterojunction films.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.45-51
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• 1985

Rate constants and activation parameters for the methanolysis of t-butyl halide (t-BuCl, t-BuBr, t-BuI) in various MeOH-DMSO mixtures were measured by conductometric method. Taft's solvatochromic parameters, such as polarity-polarizability(SPP's), ${\pi}^{\ast}$, hydrogen bond donor (HBD) acidity, ${\alpha}$, and hydrogen bond acceptor (HBA) basicity, ${\beta}$ of the solvents, were determined by the so called solvatochromic method using five indicators. The variation of methanolysis rate with the solvent composition was discussed on the basis of the activation parameters and the correlation of the rates with the solvatochromic parameters. It is concluded that the polarity-polarizability, HBD acidity and HBA basicity of the mixtures had an effect on the ionization of t-butyl halide cooperatively, also that the specific interaction between the leaving groups and the solvents, such as ion-dipole and hydrogen bond acceptor-donor interaction, is the most important factor of solvent effects on the stabilization of transition states.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.392.1-392.1
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• 2014

Isoindigo based small molecules have attracted much attention in the field of optoelectronic devices due to their broad absorbance and high charge carrier mobilitiies. Herein, we investigate the field effect transistor characteristics of a series of isoindigo based donor-acceptor-donor (D-A-D) small molecules containing a variable number of thiophene moieties (named IDT, ID2T, and ID3T) which form pi-bridges between the D and A moieites and a different donor moiety (IDED). In order to improve the carrier mobility, 1-chloronaphthalene (CN) and 1,8-diiodooctane (DIO) as solvent additives were used. The film morphology, crystallinity and optical properties of the materials processed with various concentrations of solvent additives were investigated through atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1671-1674
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• 2003

The effects of amine donors ($a:NH_2,\;b:NMe_2,\;c:NMePh,\;d:NPh_2$) and conjugation length on the molecular hyperpolarizabilities of a series of dipolar molecules have been theoretically investigated by using CPHF/6-31G method. The first hyperpolarizabilities (${\beta}$) of p-nitrobenzene derivatives increase with the donor in the order, $NH_2\;<\;NMe_2\;<\;NMePh\;<\;NPh_2$, whereas slightly different order is observed in more conjugated derivatives, i.e., $NH_2\;<\;NPh_2\;<\;NMe_2\;<\;NMePh$. The result has been attributed to the extent of charge transfer and torsion angle. Moreover, the results show that "non-traditional" ${\pi}$-conjugation effect exists in small compounds and decreases as the conjugation length between donor and acceptor increases.

• Journal of Photoscience
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• v.10 no.1
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• pp.9-20
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• 2003

Recent studies on the photoreactivity of l,4-unsaturated systems have changed some ideas that were firmly established in this area of research for many years. Thus, we have described the first examples of 2-aza-di-$\pi$-methane (2-ADPM) rearrangements promoted by triplet-sensitization and by single electron transfer (SET) using electron-acceptor sensitizers. These reactions afford N-vinylaziridine and cyclopropylimine photoproducts in the first examples of di-$\pi$-methane processes that yield three-membered ring heterocycles. l-Aza-1,4-dienes also undergo SET-promoted l-aza-di-$\pi$-methane (l-ADPM) rearrangements via radical-cation intermediates using electron acceptor sensitizers. In some cases, alternative cyclizations yielding different carbocycles and heterocycles have been observed. The l-ADPM and di-$\pi$-methane (DPM) reactions also occur via radical-anion intermediates on irradiation using electron donor sensitizers. On the other hand, the photoreactivity reported for $\beta$,${\gamma}$-unsaturated aldehydes for many years was decarbonylation to the corresponding alkenes. However, our studies demonstrate that these compounds undergo the oxa-di-$\pi$-methane (ODPM) rearrangement with high chemical and quantum efficiency. A comparison of the photochemical reactivity of $\beta$,${\gamma}$-unsaturated aldehydes and corresponding methyl ketones has shown that the ketones do not undergo the ODPM rearrangement while the corresponding aldehydes are reactive by this pathway. Monosubstituted $\beta$,${\gamma}$-unsaturated aldehydes at C-2 undergo the ODPM rearrangement yielding the corresponding cyclopropane carbaldehydes diastereoselectively. Finally, we have described the first examples of reactions, similar to the well know Norrish Type I process, which take place in the triplet excited state of $\beta$,${\gamma}$-unsaturated carbonyl compounds by excitation of the C-C double bond instead of the carbonyl group.