• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.3031-3038
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• 2011

Ion-coordinating ruthenium complexes [cis-Ru(dcbpy)(L)(NCS)$_2$, where dcbpy is 4,4'-dicarboxylic acid-2,2'-bipyridine and L is 1,4,7,10-tetraoxa-13-azacyclopentadecane, JK-121, or bis(2-(2-methoxy-ethoxy)ethyl) amine, JK-122] have been synthesized and characterized using $^1H$ NMR, Fourier transform IR, UV/vis spectroscopy, and cyclic voltammetry. The effect of $Li^+$ in the electrolyte on the photovoltaic performance was investigated. With the stepwise addition of $Li^+$ to a liquid electrolyte, the device shows significant increase in the photo-current density, but a small decrease in the open circuit voltage. The solar cell with a hole conductor, the addition of $Li^+$ resulted in a 30% improvement in efficiency. The JK-121 sensitized cells in the liquid and solid-state electrolyte give power conversion efficiencies of 6.95% and 2.59%, respectively, under the simulated sunlight.

• 공업화학
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• 제2권4호
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• pp.311-329
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• 1991

산화주석전극 위에 LB 법에 의해 단분자층상으로 흡착된 양친매성 Os 착체의 전기화학적 거동을 살펴보았다. 또한 단분자막형태로 흡착된 redox 종의 전극반응의 이론식을 가역, 비가역, 준가역파에 대하여 검토하였고, 이들막이 진공증착된 $SnO_2$ 전극 위로 전이될 때, 그 전극에서 흐른 전체 전하를 cyclic voltammogram 의 그림적분법에 의해 구하였다. 그리고 이들 단분자막을 이용한 전자이동 중개반응의 응용면도 $Fe^{2+}$, TEMPOL 등을 이용해 해석하였다. 이들 측정된 cyclic voltammogram을 이론식으로부터 유도하여 분자들간의 상호작용 parameter를 고려해서 simultation 하였다. 이들로부터 구해진 parameter 들은 측정된 cyclic voltammogram 과 거의 일치함을 확인할수 있었다. 마지막으로 LB 법을 이용한 최근의 연구동향 및 응용분야를 소개하였다.

• Bulletin of the Korean Chemical Society
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• 제10권5호
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• pp.437-442
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• 1989

The cmc's of sodium dodecyl sulfate (SDS)/Triton X-100 surfactant mixtures were determined by surface tension measurement at various surfactant compositions. The cmc values were lower than those predicted from ideal mixture. The regular solution theory was applied to calculate the interaction parameter, micellar composition, and the activity coefficients of surfactants in the mixed micelle. The interaction parameter (${\beta}$) was - 2.1. The nonideality arised largely from decreased activity of SDS in the mixed micelle. The mean aggregation numbers (${\bar{n}}$) and micropolarity of hydrocarbon region of the mixed micelles were determined by luminescence probe techniques. The total aggregation number (${\bar{n}}_{SDS}+{\bar{n}}_{TX}$) in mixed micelles showed little dependency on the composition of the micelle. The apparent dielectric constant of the hydrocarbon region of the micelle vs micellar composition plot showed positive deviation from linearity. Emission and emission quenching of excited tris(2,2'-bipyridine)ruthenium(Ⅱ) cation, $(Ru(bpy)_3^{2+})$, by methylviologen ($MV^{2+}$) were also investigated in the mixed micellar solutions. The quenching rate was lowest when the mole fraction of SDS in the surfactant mixtures (${\alpha}_{SDS}$) is about 0.25 and highest at ${\alpha}_{SDS}$ = 0.85. This was explained in terms of combined effects of binding of the cations with the micelle and mobility of the bound cations on the surface of the micelles.

• Macromolecular Research
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• 제10권6호
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• pp.339-344
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• 2002

Poly(vinyl alcohol-b-styrene) (poly(VA-b-St)) diblock copolymer containing high syndiotactic poly (vinyl alcohol) (PVA) was synthesized by the saponification of poly(vinyl pivalate-b-styrene) (poly(VPi-b-St)). For the block copolymer, poly(vinyl pivalate) (PVPi) with trichloromethyl end group was obtained via telomerization of vinyl pivalate with carbon tetrachloride as a telogen and 2,2-azobisisobutyronitrile (AIBN) as an initiator. Then resulting poly(vinyl pivalate) with trichloromethyl end group was used as an effient macroinitiator for the synthesis of poly(VPi-b-St) using atom transfer radical polymerization (ATRP) in the presence of CuCl/2,2'-bipyridine at 130 $^{\circ}C$. The poly(vinyl pivalate) macroinitiator, poly(VPi-b-St), poly(VA-b-St) were characterized by GPC, FT-IR and $^1$H-NMR. And the analysis showed that integrity of the block copolymer was maintained during saponification reaction.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1314-1318
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• 2010

The $[Ru(tpy)_2]Cl_2$ (tpy:2,2':6',2"-terpyridine) complex was synthesized and its structure was confirmed by $^1H$-NMR and elemental analysis. Its binding mode toward DNA was compared with the well-known $[Ru(bpy)_3]Cl_2$ (bpy:2,2-bipyridyl), using isotropic absorption, linear dichroism(LD) spectroscopy, and an energy minimization study. Compared to $[Ru(bpy)_3]^{2+}$, the $[Ru(tpy)_2]^{2+}$ complex exhibited very little change in its absorption pattern, especially in the MLCT band, upon binding to DNA. Furthermore, upon DNA binding, both Ru(II) complexes induced a decrease in the LD magnitude in the DNA absorption region. The $[Ru(tpy)_2]^{2+}$ complex produced a strong positive LD signal in the ligand absorption region, which is in contrast with the $[Ru(bpy)_3]^{2+}$ complex. Observed spectral properties led to the conclusion that the interaction between the ligands and DNA bases is negligible for the $[Ru(tpy)_2]^{2+}$ complex, although it formed an adduct with DNA. This conclusion implies that both complexes bind to the surface of DNA, most likely to negatively charged phosphate groups via a simple electrostatic interaction, thereby orienting to exhibit the LD signal. The energy minimization calculation also supported this conclusion.

• 공업화학
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• 제23권2호
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• pp.241-246
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• 2012

크롬(VI)-헤테로고리 착물(2,2'-bipyridinium dichromate)를 합성하여, 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매 하에서 2,2'-bipyridinium dichromate를 이용하여 벤질 알코올의 산화반응을 측정한 결과 유전상수(${\epsilon}$) 값이 큰 용매 순서인 시클로헥센 < 클로로포름 < 아세톤 < N,N-디메틸포름아미드 용매 하에서 높은 산화반응성을 보였다. 산 촉매($H_2SO_4$)를 이용한 DMF 용매 하에서 2,2'-bipyridinium dichromate는 벤질 알코올과 그의 유도체들($p-OCH_3$, $m-CH_3$, H, $m-OCH_3$, m-Cl, $m-NO_2$)을 효과적으로 산화시켰다. 그리고 전자받개 그룹들은 반응 속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰다. 또한 Hammett 반응상수$({\rho})$ 값은 -0.66 (303 K)이였다. 그러므로 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어나는 메카니즘임을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1777-1783
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• 2014

Four $Cd^{II}$ MOFs, $[Cd_2({\mu}-succinate)_2(H_2O)_2]{\cdot}H_2O$ (1A), $[Cd_2({\mu}-succinate)_2({\mu}-4,4^{\prime}-bpy)_2]{\cdot}H_2O$ (1B), $[\{Cd_2({\mu}-succinate)_2\}({\mu}-bpa)_2\{Cd(H_2O)_2\}(NO_3)_2]{\cdot}H_2O$ (2), and $[Cd({\mu}-succinate)({\mu}-bpp)_2]{\cdot}2H_2O$ (3), with various bipyridyl ligands (4,4'-bipyridine (4,4'-bpy), 1,2-bis(4-pyridyl)ethane (bpa), and 1,3-bis(4-pyridyl)propane (bpp)) were prepared, and their structures were determined using X-ray crystallography. The structures and dimensionalities of $Cd^{II}$-(succinate) compounds varied depending on the auxiliary ligands. Heterogeneous catalytic activity for transesterification reactions, photoluminescence and the thermal stabilities of these compounds were also examined.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.587-596
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• 2014

A new ${\pi}$-stacked donor-acceptor (D-A) system, [Ru(1-([2,2'-bipyridine]-6-yl-methyl)-3-(2-cyclohexa-2',5'-diene-1,4-dionyl)-1H-imidazole)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (ImQ_T), has been synthesized and characterized. Similar to its precedent, [Ru(6-(2-cyclohexa-2',5'-diene-1,4-dione)-2,2':6',2"-terpyridine)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (TQ_T), this system has a cofacial alignment of terpyridine (tpy) ligand and quinonyl (Q) group, which facilitates an electron transfer through ${\pi}$-stacked manifold. Despite the presence of lowest-energy charge transfer transition from the Ru-based-HOMO-to-Q-based-LUMO (MQCT) predicted by theoretical calculations by using time-dependent density functional theory (TD-DFT), the experimental steady-state absorption spectrum does not exhibit such a band. The selective excitation to the Ru-based occupied orbitals-to-tpy-based virtual orbital MLCT state was thus possible, from which charge separation (CS) reaction occurred. The photo-induced CS and thermal charge recombination (CR) reactions were probed by using ultrafast visible-pump/mid-IR-probe (TrIR) spectroscopic method. Analysis of decay kinetics of Q and $Q^-$ state CO stretching modes as well as aromatic C=C stretching mode of tpy ligand gave time constants of <1 ps for CS, 1-3 ps for CR, and 10-20 ps for vibrational cooling processes. The electron transfer pathway was revealed to be Ru-tpy-Q rather than Ru-bpy-imidazol-Q.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.287-291
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• 1985

The addition of poly(styrenesulfonate) (PSS) to $Ru(bpy)_3^{2+}$ solutions shifted the emission peak by 3 nm to red, and increased emission intensity by 1.8 times. By contrast, poly(vinylsulfonate) (PVS) had little effect on the fluorescence spectrum. The effects of PSS on the spectral properties of $Ru(bpy)_3^{2+}$, were attributed to the presence of a hydrophobic phenyl group in PSS, which interact with $Ru(bpy)_3^{2+}$ by, at least in part, hydrophobic effect. The binding constant of $Ru(bpy)_3^{2+}$ to PSS in 0.1 M NaCl was $6{\times}10^4\;M^{-1}$, and this value was about $10^3$ times higher than those of methyl viologen ($MV^{2+}$) and $Cu^{2+}$. The Stern-Volmer constants of emission quenching of $Ru(bpy)_3^{2+}$ by $MV^{2+}$ and $Cu^{2+}$ in 0.1 M NaCl solutions were 426 and 40 $M^{-1}$, which correspond to second order rate constants($k_q$) of $1.1{\times}10^9\;and\; 1.0{\times}10^8\;M^{-1}s^{-1}$, respectively. The presence of PSS enhanced $K_{SV's}\;by\;{\sim}50$ times, whereas PVS increased the values only 1-4 times. The large enhancing effect of PSS, despite of lower charge density than PVS, was explained in terms of longer life-time of photoexcited $Ru(bpy)_3^{2+}$ bound to PSS and strong association of $Ru(bpy)_3^{2+}$ to PSS due to a specific interaction involving hydrophobic effect. The variation of $K_{SV's}$ on the concentrations of PVS and PSS were also investigated for $Ru(bpy)_3^{2+}-MV^{2+}\;and \;Ru(bpy)_3^{2+}-Cu^{2+}$ photoredox systems.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1744-1748
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• 2002

Trifluoroacetate anion as a connector has been studied on $AgCF_3CO_2$ with 3,3'-$Py_2X$(X=O vs S) produces 1 : 1 adducts of [Ag($CF_3CO_2$)(3,3'-$Py_2X<$)]. Crystallographic characterization of [Ag($CF_3CO_2$)(3,3'-$Py_2X$)](monoclinic $P2_1$a=7.383(1)$\AA$b=19.801(3)$\AA$c=9.297(3)$\AA$,$\beta$=$100.26(2)^{\circ}$,V=1337.4(5) $\AA^3$, Z=2, R=0.0386) reveals that the 3,3'-$Py_2O$ spacer connects two silver ions to give a single strand and that the single strands are linked via the trifluoroacetate anions in an "up and down even-bridge" to give an elegant molecular grid. The framework of [$Ag(CF_3CO_2)(3,3'-Py_2X)$](monoclinic $P2_1/c$a=8.331(2)$\AA$b=14.010(2)$\AA$,c=11.926(3 $\AA$$\beta$=$93.70(2)^{\circ}$=1385.1(6)$\AA^3$, Z=4, R=0.0589) is a single-strand. The single strands are connected via the trifluoroacetate anions in a double-bridge, resulting in a typical molecular chicken-wire. The trifluoroacetate anion as a connector appears to be primarily associated with its moderately coordinating ability. Their structural features have been discussed based on the anion exchangeability. Thermal analyses indicate that the compounds are stable up to approximately $200^{\circ}C$.