Electrical property of mesoporous Pt electrode and its application

한지훈 Graduate School, Yonsei University 2011 국내박사

Syntheses of new porous metal-organic frameworks and studies on application in hydrogen storage and carbon dioxide capture

박혜정 서울대학교 대학원 2012 국내박사

PART I. HYDROGEN STORAGE IN METAL-ORGANIC FRAMEWORKS Two 3D porous metal-organic frameworks, {[Cu2(BPnDC)2(bpy)]∙8DMF∙6H2O}n (1) and {[Zn2(BPnDC)2(bpy)]∙2DEF•2MeOH}n (2), have been prepared by the solvothermal syntheses using same organic building blocks. 1 is a non-interpenetrating framework generating 2D channels with effective pore sizes of 18.2 Å and 11.4 Å, while 2 is a doubly interpenetrated network generating curved 3D channels. In addition, during the guest removal process, the framework structure of 1 is retained, but that of 2 significantly changes. Because the gas sorption properties are affected by the framework structures and the flexible nature of the framework, the gas sorption properties of desolvated solid of 1 (SNU-6) and 2 (SNU-9) are totally different; SNU-6 exhibits high permanent porosity (1.047 cm3g-1) with high Langmuir surface area (2914 m2g-1) and high H2 storage capacity (1.68 wt% at 77 K and 1 atm; excess 4.87 wt% and total 10.0 wt% at 77 K and 70 bar), while SNU-9 shows three-step adsorption for N2 and O2 gases, and two-step adsorption for CO2 and H2 gases with large hysteresis on desorption. To increase the isosteric heat of the H2 adsorption, 18-crown-6 and 15-crown-5 are included as neutral organic guests into a porous MOF (SNU-6). The experimental and theoretical studies indicate that the inclusion of 18C6 and 15C5 in a porous MOF significantly increases Qst of the H2 adsorption by ca. 2.8 kJ mol-1 (experimental) and ca. 4.9 kJ mol-1 (theoretical). A doubly interpenetrated porous metal-organic framework ([Zn4O(TCBPA)2]•19DMA•4H2O; SNU-77) has been synthesized from the solvothermal reaction of an extended carboxylic acid tris(4-carboxybiphenyl)amine (H3TCBPA) and Zn(NO3)2∙6H2O in N,N-dimethylacetamide (DMA). To see the effects of the activation methods on the framework strcuture and the gas sorption properties of a MOF, three different activation methods such as room temperature evacuation, supercritical CO2 drying, and high temperature evacuation have been employed. SNU-77 undergoes single-crystal to single-crystal transformations during the various activation processes. These guest-free MOFs exhibit different fine structures having different window shapes and different effective window sizes at room temperature. The variable temperature synchrotron X-ray single-crystal analyses reveal that the guest-free structure is affected also by the temperature change. Despite the different fine structures, SNU-77R, SNU-77S, and SNU-77H show similar gas sorption properties due to the nonbreathing nature of the framework and an additional structural change upon cooling to cryogenic gas sorption temperature. Keywords: metal-organic framework • porosity • hydrogen storage • isosteric heat • single-crystal to single-crystal transformation • activation method PART II. CARBON DIOXIDE CAPTURE ABILITY AND LUMINESCENCE PROPERTY OF METAL-ORGANIC FRAMEWORKS A new anionic MOF including dimethylammonium cations in the 1D channels, [Zn3(TCPT)2(HCOO)][NH2(CH3)2]•5DMF (SNU-100, TCPT = 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine) has been synthesized. To investigate the effect of the impregnated metal ions in the pores of MOF on the gas sorption properties, the dimethylammonium included in [Zn3(TCPT)2(HCOO)][NH2(CH3)2]•6MeOH (SNU-100m) was post-synthetically exchanged with Li+, Mg2+, Ca2+, Co2+, and Ni2+ ions. The experimental and theoretical studies reveal that the impregnation of various metal ions remarkably enhances the CO2 capture ability (CO2 storage capacity, isosteric heats of CO2 adsorption, and adsorption selectivities of CO2 over N2 at room temperature) of the MOF without any energy penalty for reversible regeneration due to the electrostatic interactions between CO2 and the extra-framework metal ions. To simultaneously achieve a large CO2 storage capacity and selectivity for CO2 over other gases in a compound, a core-shell crystal, which is constructed by a core crystal with a large CO2 storage capacity and a shell crystal with a selective CO2 adsorption property, is designed and prepared. That is, two frameworks, [Zn2(TCPBDA)(H2O)2]•30DMF•6H2O (SNU-30) and [Zn2(TCPBDA)(bpta)]•23DMF•4H2O (SNU-31), are successfully hybridized into one crystal by a simple immersion of SNU-30 crystals in a saturated DMF solution of bpta at room temperature. The gas sorption studies for the hybridized core-shell crystals show that gas sorption properties such as gas uptake capacity, step-wise adsorption, and desorption hysteresis can be modulated by tuning the thickness of shell crystal. A doubly interpenetrated 3D porous metal-organic framework, [Zn3(TCBT)2(DMA)2]∙18DMA∙9H2O (SNU-101), has been synthesized by using triazine-based tricarboxylic acid. The desolvated crystal (SNU-101’) exhibits a high surface area (BET, 3080 m2g-1) and high gas uptake capacities for N2, O2, and CO2. In particular, the CO2 adsorption capacities of SNU-101’ (151 wt% at 195 K and 1 atm; 71.3 wt% at 298 K and 50 bar) are superior to those for other MOFs measured under similar conditions. New MOFs exhibiting electrochemiluminescence, [Zn4O(bcbtda)3]∙18DEF (SNU-60), [Zn2(TCPBDA)(bpbtda)]∙20DMF∙8H2O (SNU-61), [Zn2(TCBBDA)(bpbtda)]∙35DMF∙18H2O (SNU-62), [Zn2(TCBBDA)(bpbtda)]∙24DEF∙4H2O (SNU-63), and [Zn2(TCDbtda)(DMA)2]∙8DMA∙4H2O (SNU-64), have been prepared. In the photoluminescence studies, SNU-60 displays a green emission at 569 nm and the other MOFs (SNU-61, SNU-62, SNU-63, and SNU-64) show orange emissions (627 nm, 632 nm, 649 nm, and 635 nm, respectively) due to the electron transfer between 2,1,3-benzothiadiazole as the electron acceptor and triphenylamine as the electron donor, while TCPBDA, TCBBDA, and bcbtda show luminescence at 475 nm, 527 nm, and 513nm, respectively. The photoluminescence of SNU-60 is strongly dependent on the electron-donating ability of aromatic guests; benzonitrile (510 nm), tolene (522 nm), xylene (524 nm), nitrobenzene (524 nm), aniline (574 nm), 3,5-dimethylaniline (576 nm), and N,N-dimethylaniline (605 nm). In addition, the desolvated solids SNU-62’ and SNU-63’ show the selective CO2 adsorption over N2, H2, and CH4 gases. Keywords: metal-organic framework • carbon dioxide capture • isosteric heat • selectivity • core-shell crystal • electrogenerated chemiluminescence

덴드리머 내부에 합성된 나노 입자가 고정화된 인듐-주석산화물 전극에서 방출되는 향상된 Ru(bpy)₃²+/TPrA의 전기화학적 발광과 응용

김여주 경희대학교 대학원 2014 국내석사

이 논문에서는 덴드리머 내부에 합성된 촉매성을 가진 나노 입자가 고정화된 인듐-주석산화물 (ITO) 전극에서 공반응 화합물로써 tripropylamine(TPrA)이 존재할 때, Ru(bpy)₃²+ (bpy = 2,2’-bipyridyl)의 전기화학적 발광이 향상된다는 사실을 보고한다. 덴드리머 내부에 합성된 나노 입자가 ITO 전극에 고정화되었음에도 불구하고 ITO 전극의 투명성은 유지되었으며 이 수정된 전극은 전기화학적 발광을 기반으로 하는 센서로 응용할 수 있다. 먼저 amine-terminated sixth generation polyamidoamine dendrimer를 사용하여 Pt와 Au dendrimer-encapsulated nanoparticles (DENs)를 합성하였다. 그 후, 덴드리머의 아민 말단기를 전기산화적 고정법으로 ITO 전극 표면에 결합시킴으로써 DENs를 ITO 전극 표면에 고정화할 수 있었다. DENs가 고정화된 ITO 전극은 투명성을 유지하고 있었으며 Ru(bpy)₃²+/TPrA의 전기화학적 산화를 매우 촉진시켜 증가된 전기화학적 발광을 관찰할 수 있었다. 특히 Pt DENs가 고정화된 ITO 전극에서는 가시광선 영역에서의 투과율이 bare ITO 전극과 비교했을 때, ~2.11 %만이 감소하였지만 전기화학적 발광은 213 배가 증가하였고 0.00 `에서 1.10 V 까지의 순환 전압을 10 번 반복하여 걸어주었을 때 안정적인 전기화학적 발광이 관찰되었다. 이러한 결과는 Pt DENs가 고정화된 ITO 전극이 bare ITO 전극보다 ~329 배 감도가 좋은 전기화학적 발광을 기반으로 하는 니코틴 분석을 가능하게 하였다. Here, I report highly enhanced stable electrogenerated chemiluminescence (ECL) of Ru(bpy)₃²+ (bpy = 2,2’-bipyridyl) with tripropylamine (TPrA) coreactant on indium tin oxide (ITO) electrodes modified with amine-terminated dendrimers encapsulating catalytic nanoparticles while maintaining optical transparency of ITO, and feasibility of the modified ITOs to sensitive ECL-based assays. As model systems, we prepared Pt and Au dendrimer-encapsulated nanoparticles (DENs) using amine-terminated sixth generation polyamidoamine dendrimers, and subsequently immobilized the DENs onto ITO surfaces via electrooxidative grafting of the terminal amines of dendrimers to the surfaces. The resulting DENs-modified ITOs preserved good optical transparency of ITO, and exhibited highly catalyzed electrochemical oxidation of Ru(bpy)₃²+/TPrA, leading to significantly increased ECL emission. Especially, the Pt DENs-modified ITO electrode provides negligible transmittance drop, i.e. only ~2.11 % over the entire visible region, and exhibited not only much enhanced (i.e. ~213-fold increase compared to ECL obtained from bare ITO), but also stable ECL emission under consecutive potential scans from 0.00 to 1.10 V for 10 cycles, which allowed ~329 times more sensitive ECL-based analysis of nicotine using the Pt DENs-modified ITO compared with the use of bare ITO.

Tris(2,2'-bipyridyl)ruthenium(Ⅱ) electrogenerated chemiluminescence sensor based on titanium carbide/nafion composite films

이의태 Graduate School, Yonsei University 2021 국내석사

Recently, as technology advances, sensors have been miniaturized to produce portable diagnosis electronics. Highly sensitive systems are needed for the detection of biomaterials. However, high-sensitivity analysis systems such as mass spectrometers could not be miniaturized because they are too complex. Electrogenerated chemiluminescence is a simple and highly sensitive analysis method for analyte quantification through generation of chemiluminescence from an electrochemical reaction. The sensitivity and selectivity can be increased through the modification of the electrode and the selection of proper shape, type, position of the electrode. In addition, the chemical reactions can be controlled by modulating the applied potential. In this study, mesoporous Nafion composite doped with titanium carbide (Ti3C2) has been used for the immobilization of tris(2,2‐bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to fabricate a solid‐state electrogenerated chemiluminescence (ECL) sensor. The present ECL sensor showed improved ECL sensitivity, amount of adsorbed Ru(bpy)32+ on the electrode surface, diffusion rate, and conductivity of composite, as compared to the ECL sensors based on pure Nafion films. Ti3C2 has been compared to other carbon materials such as graphene and CNT. Ti3C2 showed a good ECL response for TPA concentrations from 50 nM to 1.0 mM with an outstanding detection limit (S/N = 3) of 10 nM. For comparison, the ECL sensors based on pure Nafion film, MWCNT/Nafion, graphene/Nafion composite gave a detection limit of 1 μM, 50 nM and 50 nM, respectively. Through selectivity test, it was confirmed various amines could be detected with the developed method without being affected by urea.

Electrogenerated chemiluminescent probes for sulfide based on cyclometalated Ir(III) complexes

김서연 서울대학교 대학원 2017 국내석사

황화 이온을 효과적으로 검출하기 위한 다양한 화학 센서의 개발이 이루어져 왔다. 그러나 기존의 방법들은 분석 과정이 복잡하고 부피가 큰 측정 장비가 필요하기 때문에 임상 응용되기에 어려움이 있었다. 전기화학적 발광을 기반으로 한 화학 센서는 기존의 분석 방법들에 비해 감도가 높고 배경 신호가 없으며 검출 장비가 간단하다는 장점들이 있다. 이러한 특징들을 바탕으로, 전기화학발광 센서는 간편하게 임상 진단을 할 수 있는 현장 진단 장비로 개발될 수 있다. 우리는 고리형 이리듐 착물을 기반으로 하여, 황화 이온을 검출하기 위한 두 개의 전기화학적 발광 화학 센서 (1, 2)를 개발하였다. 다이나이트로페닐기를 광유발 전자 전달 소광체이자 황화 이온과의 반응 자리로써 이리듐 착물에 도입하였다. 다이나이트로페닐기는 황화 이온과 친핵성 고리 치환 반응을 하여 이리듐 착물로부터 분리되고 그에 따른 인광과 전기화학적 발광의 증가를 유도하였다. 탐지체 1과 2의 전기화학적 발광은 0-8 당량의 황화 이온 존재 하에 선형 상관관계를 보였다. 그리고 두 탐지체 모두 상당히 낮은 검출 한계를 보여주었다. 또한, 탐지체 1과 2는 다른 음이온들이나 바이오티올과는 반응하지 않고, 오직 황화 이온과 선택적으로 반응하여 전기화학발광을 크게 증가시켰다. 황화 이온을 효과적으로 검출하기 위한 다양한 화학 센서의 개발이 이루어져 왔다. 그러나 기존의 방법들은 분석 과정이 복잡하고 부피가 큰 측정 장비가 필요하기 때문에 임상 응용되기에 어려움이 있었다. 전기화학적 발광을 기반으로 한 화학 센서는 기존의 분석 방법들에 비해 감도가 높고 배경 신호가 없으며 검출 장비가 간단하다는 장점들이 있다. 이러한 특징들을 바탕으로, 전기화학발광 센서는 간편하게 임상 진단을 할 수 있는 현장 진단 장비로 개발될 수 있다. 우리는 고리형 이리듐 착물을 기반으로 하여, 황화 이온을 검출하기 위한 두 개의 전기화학적 발광 화학 센서 (1, 2)를 개발하였다. 다이나이트로페닐기를 광유발 전자 전달 소광체이자 황화 이온과의 반응 자리로써 이리듐 착물에 도입하였다. 다이나이트로페닐기는 황화 이온과 친핵성 고리 치환 반응을 하여 이리듐 착물로부터 분리되고 그에 따른 인광과 전기화학적 발광의 증가를 유도하였다. 탐지체 1과 2의 전기화학적 발광은 0-8 당량의 황화 이온 존재 하에 선형 상관관계를 보였다. 그리고 두 탐지체 모두 상당히 낮은 검출 한계를 보여주었다. 또한, 탐지체 1과 2는 다른 음이온들이나 바이오티올과는 반응하지 않고, 오직 황화 이온과 선택적으로 반응하여 전기화학발광을 크게 증가시켰다. A variety of chemosensors have been developed for the detection of H2S. However, most conventional methods require bulky equipment and complicated operations during their anlaysis processes, preventing their use for simple detections for clinical applications. Electrogenerated chemluminsecnece (ECL)-based chemosensors provide several advantages over existing analytical techniques, including no background signal, high sensitivity, and cost-and time-efficient analysis with simple sensing tools. These features enable ECL systems to be powerful candidates for point-of-care (POC) detection tools. In this study, we designed and synthesized two ECL chemosensors (1, 2) for sulfide anion based on Ir(III) complexes. The dinitrophenyl (DNP) group was introduced to the Ir(III) complex as a photo-induced electron transfer (PET) quencher as well as a reaction site with sulfide. In the presence of sulfide, the DNP group was cleaved through nucleophilic aromatic substitution (SNAr), inducing a great enhancement of phosphorescence and ECL. Probe 1 and 2 increased the ECL signals with a linear correlation in the range of 0 to 8 equiv of sulfide, and the limit of detection (LOD) was calculated to be a low value in both cases. In addition, probe 1 and 2 exhibited highly selective ECL responses toward sulfide over various anions and biothiols.

Electrogenerated chemiluminescence based on biocompatible gold nanoclusters and carbon quantum dots in aqueous solution and their analytical applications

김재윤 Graduate School, Yonsei University 2021 국내박사

물질이 나노 단위의 크기가 됨에 따라 높은 전기화학적 반응성이나 새로운 광학적 특성 같은 기존의 물질 (nanomaterials)이 가지고 있는 특성이 아닌 새로운 특성을 띄게 된다. 이러한 이유로 최근 나노 물질을 이용한 다양한 분야로의 응용에 대한 연구들이 진행되고 있다. 전기화학발광 (electrogenerated chemiluminescence, ECL)을 이용한 분석화학에서 또한 이러한 나노 물질의 쓰임새는 나날이 늘어나고 있으며 특히 양자점 (quantum dots)에 대한 수많은 연구들이 쏟아지고 있는 상황이다. 하지만 높은 광자 효율을 발생시키는 대부분의 양자점은 카드뮴 (Cd), 텔루륨 (Te), 셀레늄 (Se) 등과 같은 중금속을 포함하고 있어 유독하다는 고질적인 단점을 가지고 있다. 본 연구에서는 이러한 부분을 보완하고자 중금속을 포함하지 않는 생체 친화적인 나노 물질을 선정해 전기화학발광 시스템에 도입하고 새로운 전기화학발광 센서로의 응용을 추구해 보고자 하였다. 먼저3단원에서는 최근 연구에서 전기화학발광 분야에서 가장 많이 사용되는 Ru(bpy)2+ 보다도 높은 광자 효율 (quantum yield, QY)을 보여주었던 Au22(SG)18 NCs를 TPA가 상호 반응물 (coreactant)로 사용하는 전기화학발광 시스템에 도입하여 새로운 생체 친화적이며 높은 효율을 내는 전기화학발광 센서로의 응용을 해보고자 하였다. 이러한 Au22(SG)18 NCs와 TPA를 이용한 전기화학발광 시스템은 약 1.25 V에서 높은 근적외선 범위 (near-infrared)의 전기화학발광을 발생시켰으며, Au@BSA같은 다른 금 나노 입자들보다도 월등히 강한 전기화학발광을 보여주었다. 또한, 반응 메커니즘 상의 라디컬(radicals)들에 전자를 제공해 안정화시킬 수 있는 물질인 페놀류들을 소광 (quenching) 물질로 사용해 그를 검출할 수 있는 시스템을 구축하였고, 그 중 가장 높은 소광 효과를 나타내는 카테콜 (catechol)을 선정하여 검량선 (calibration curve)을 작성한 결과, 1.0 x 10-7에서 1.0 x 10-4 M의 선형범위 (linear range)와 3.3 x10-9 M의 검출한계 (detection limit)을 보여주었다. 다음으로 금 나노 입자 (gold nanoclusters)와 그래핀 (graphene), 나피온 (Nafion)을 이용해 복합막을 형성하고 유리상 탄소 (GC) 전극에 두텁게 도포하여 개질한 전극을 이용하여 루미놀 (luminol)에 대한 전기화학발광의 동향을 파악해 보았다. 금 나노 입자의 산소의 환원에 대한 촉매 효과 (catalytic effect)로 인해 상호 반응물의 역할을 하는 산소 라디컬의 생성이 비약적으로 상승했으며 이를 통해 매우 높은 효율의 전기화학발광 시스템을 구축할 수 있었다. 또한, 과산화수소를 첨가하여 약 -0.01 V에서의 추가적인 환원반응을 유도했으며 이 전위에서 발생하는 전기화학발광을 기반으로 한 검량선의 작성한 통해 1.0 x 10-8 M에서 4.0 x 10-6 M의 선형범위와 2.21 x 10-9 M의 검출한계를 가지는 센서를 개발하는데 성공하였다. 마지막으로 매우 저렴하고 생체 친화적인 물질인 탄소 양자점(carbon quantum dots, CQDs)과 persulfate를 상호 반응물로 사용하는 전기화학발광 시스템을 구축하고자 하였다. 탄소 양자점은 reflux를 이용한 방법으로 합성되었으며 TEM, XRD, XPS, FT-IR, PL 흡수/방출(absorption/emission)을 통해 특성분석을 진행하였다. 이렇게 구축된 시스템은 약 -1.9 V에서 강한 음극성 (cathodic) 전기화학발광을 발생시켰으며 이를 통해 ascorbic acid를 검출할 수 있음을 증명하였다. 최종적으로 탄소 양자점에 이온성 액체 (ionic liquids)를 추가하여 복합막을 형성하고 전극을 개질하여 약 4.2배의 전기화학발광을 증폭시키는 개질 전극의 제작에 성공하였다.

Studies on the development of electrogenerated chemiluminescent (ECL) chemosensors using cyclometalated Ir(III) complex

김훈준 Seoul National University 2017 국내박사

The development of effective chemosensors for detecting small-molecule biotargets has been attracted significant attention in biosensing researches for a long time. Among them, ECL-based chemosensors have several advantages over the conventional analytical techniques such as high sensitivity, good reproducibility, and simple analytic process. Part I describes the development of fluorescent chemosensors for phosphate-containing anions and their application to ECL. Through these investigations, we confirmed that it is possible to apply the same principles of designing fluorescent chemosensors to ECL analysis. Moreover, these studies also showed the both high sensitivity and simplicity of ECL-based detecting systems. First, coumarin-based fluorescent chemosensor 1-2Zn was developed for the sensitive sensing of pyrophosphate (PPi). 1-2Zn has bis(2-pyridylmethyl)amine (DPA)-Zn2+ complex as a selective recognition sites for PPi and a coumarin fluorophore as a signaling unit. 1-2Zn showed an improved detection limit for PPi compared to that of the naphthyl-based PPi sensor due to the introduction of coumarin dye. In addition, it showed good selectivity for PPi over other anions. Additionally, the new chemosensor 2-2Zn was developed for the discrimination of PPi, ATP, and GTP in aqueous solution. The fluorescence changes of 2-2Zn for each phosphate-containing anions resulted from the structural change (excimer formation) and from photo-induced electron transfer (PET) quenching. 2-2Zn induced a little red-shifted emission change when PPi was added, while it led to enhanced fluorescence and fluorescence quenching without a wavelength shifts upon the addition of ATP and GTP, respectively. Lastly, the pyrene-based turn-on probe 3 for organophosphate nerve agents was developed. Probe 3 showed highly sensitive and rapid detection capabilities through intramolecular cyclization. In addition to PL study, we carried out the ECL experiment for diethyl chlorophosphate (DCP) for the first time. Though PET quenching efficiency of probe 3 in ECL analysis was lowered due to the oxidation of tertiary amine and the ECL efficiency of pyrene in oxidative reduction process was lower than previously known ECL luminophores such as Ru(bpy)32+, it was still possible to detect and quantify the nerve agents with high sensitivity. In Part II, highly sensitive ECL chemodosimeters for small anions based on cyclometalated Ir(III) complex were presented. For high ECL efficiency, phenylisoquinoline (PIQ) unit which has ideal HOMO/LUMO energy levels was selected as a main ligand of Ir(III) complex. Probe 4 was synthesized for ECL determination of homocysteine, which selectively reacts with Hcy then produces efficient light emission via an electrochemical process. Formyl groups in the main ligands of probe 4 underwent a ring-formation reaction with Hcy, triggering changes in the thermodynamic and photophysical properties of the probe itself. The level of Hcy was successfully monitored in 99.9% aqueous media with a linear correlation between 0-40 μM. The mechanistic explanation has also been suggested based on the electrochemical and theoretical studies. The ECL analytical method would enable point-of-care testing of Hcy levels and is potentially useful for precautionary diagnosis of cardiovascular diseases. To improve the reactivity between probe 4 and Hcy, probes 5 and 6 were developed, bearing an additional methoxy group as an electron-donating group relative to the original probe 4. Specifically, probe 5 showed improve properties compared to probe 4, including a faster reaction time, higher sensitivity, and a higher turn-on ratio. The methoxy groups in probe 5 induced the destabilization of HOMO energy level, which resulted in the improved reaction rate and fully-quenched initial ECL intensity. Probe 5 showed 15-times lower detection limit and 1.9-times faster reaction time as compared to those of probe 4. This study provided the new strategy with which to design Ir(III)-complex-based molecular probe with high sensitivity and reactivity via the modulation of energy levels with additional substituents. In the next step, the ECL turn-on probe 7 for cyanide based on Ir(III) complex was designed and synthesized. Probe 7 possessed phenyl isoquionline groups as main ligands with dicyanovinyl groups as the reaction sites for cyanide. In the presence of cyanide, the red ECL emission of probe 7 was greatly increased with good selectivity. Probe 7 showed the linear correlation in the range of 0 to 0.4 mM when the probe concentration was 10 uM in an aqueous solution. We conducted a quantification test through a standard addition analysis in tap water successfully with high reliability and reproducibility. Theoretical studies were carried out for the rational design of probe by predicting the HOMO/LUMO energy levels and electronic distributions. Lastly, Ir(III) complex 8 was developed for the selective sensing of sulfide. Probe 8 has two different parts of reaction sites, unsaturated acrylated and dinitrobenzenesulfornyl (DNBS) group. The unsaturated acrylate unit reacted with sulfide selectively, inducing phosphorescence and leading to an ECL enhancement in the blue-shifted region. In addition, the DNBS group was well-known PET quencher which could be cleaved by sulfide and other biothiols such as cysteine or homocysteine. Probe 8 showed high sensitivity and good selectivity by given the introduction of two reaction sites in a single molecule. In Part III, the rational design and mechanistic study of Ir(III)-based ECL probes by tuning the LUMO level were presented. Because the LUMO energy level of emitter is closely related to ECL efficiency during TPA coreactant process, it is possible to develop ECL chemosensors in a new way that differs from the methods used to create fluorescent chemosensors by controlling LUMO level with a specific reaction site for the analyte. We selected the (ppy)2Ir(acac) complex as a backbone molecule and introduced the specific functional groups to various position of phenylpyridine. Three ppy-based Ir(III) complexes bearing formyl group as a reaction site for were developed. The formyl groups in pyridine rings strongly stabilized the LUMO level, and the additional substituents served to modulate the HOMO and LUMO levels while maintaining the HOMO-LUMO energy gap of each iridium complex. The OMe_acac complex showed different signal changes in PL and ECL upon the addition of cyanide. An obvious ratiometric change was observed in PL, whereas the ECL signal decreased. The electron-donating methoxy group meta substituted to coordinated Ir(III) metal in OMe_acac made the HOMO and LUMO energy level unstable, leading to the hard generation of excited states during ECL process. In contrast, H_acac and Br_acac showed similar results in terms of PL and ECL dure to their relatively stabilized LUMO levels. Next, we used boronate groups to Ir(III) complexes as a reaction site for H2O2. In this case, the change of HOMO and LUMO levels depended on the substitution location. Probe 9 and 11 showed a phosphorescent change from yellow to green upon the addition of H2O2, whereas probe 10 showed a phosphorescent change from yellow to green under an identical condition. Probe 12 showed a phosphorescent change similar to those of 9 and 11; however, the modification of pyridyl rings had a strong influence on the LUMO energy level, while the modification of the phenyl rings mainly affected to HOMO energy levels. The destabilization of the LUMO level of probe 12 upon the addition of H2O2 degraded the ECL efficiency by blocking the ECL electron transfer process. The ECL intensity of 12 was greatly decreased upon the addition of H2O2 compared to the results with other probes, demonstraing an outcome similar to that of the PL study. This work provided the rational design of ECL probe based on ECL quenching route via the control of the LUMO level, which is a differentiated strategy for the development of general fluorescence-based probes.

Electrogenerated chemiluminescence sensors based on quantum dots and mesoporous platinum electrode

남성주 Graduate School, Yonsei University 2020 국내박사

나노기술은 전기화학 센서 개발에 아주 중요한 역할을 하는 요소 중 하나이다. 본 논문에서는 여러 가지 나노물질을 사용하여 간단하고, 높은 감도와 선택성을 가진 전기화학발광 (electrogenerated chemiluminescence, ECL) 센서를 개발하였다. 본 논문에서는 총 세 가지 주제로 연구가 진행되었다. 첫째, 키토산-이산화티탄 (TiO2)-셀린화카드뮴/항화아연 (CdSe/ZnS) 양자점 (QD)으로 구성된 복합막을 이용한 전기화학발광 센서를 개발하였다. 양자점의 전기화학발광은 과황산염 (persulfate, S_2 O_8^(2-)) 을 통한 공반응물 (co-reactant) 전기화학발광을 이용하여 방출된 빛의 세기를 향상시켰으며, 졸겔법 (sol-gel method) 을 통하여 제작된 이산화티탄을 복합막에 추가하여 추가적인 신호 증폭을 확인할 수 있었다. 개발된 복합막을 바탕으로 전기화학발광 소광 효과를 이용하여 아스코르브산 (vitamin C) 과 다양한 페놀성 화합물 검출이 가능하였다. 또한, 복합막의 구성을 조정하여 센서의 감도를 조절할 수 있을 것이라 예상된다. 둘째, 다공성 백금 (mesoporous platinum) 전극 표면에서 루시게닌 (lucigenin) 전기화학발광 반응을 확인하였고, 이를 바탕으로 진행한 초과산화물 불균등화효소 (superoxide dismutase, SOD) 검출을 통하여 생물 감지 응용성을 확인할 수 있었다. 전극 개질을 통하여 확장된 다공성 백금 전극의 표면적을 계산하여 일반 백금 전극과 비교하였으며, 다공성 백금 전극 표면에서의 루시게닌 전기화학발광의 메커니즘을 제안하였다. SOD와 루시게닌의 전기화학발광 소광 효과를 통하여 개발된 센서는 SOD 검출에 응용되었고, 높은 감도와 뛰어난 선택성을 보여주었다. 마지막으로 다공성 백금 전극 표면에서의 루미놀 (luminol) 전기화학발광을 사용한 비효소적 포도당 (glucose) 센서를 개발하였다. 다공성 백금 전극에서 루미놀의 전기화학발광이 크게 증가하는 특성을 바탕으로 루미놀과 포도당 간의 소광 효과를 이용하여 포도당을 검출하였다. 개발된 바이오센서는 효소를 사용하지 않고도 포도당에 대해 높은 감도와 높은 선택성을 보였다. Nanotechnology has been one of the essential components in development of effective sensors in the field of electroanalytical chemistry. In this dissertation, several nanomaterials are utilized in development of simple, highly sensitive, and highly selective electrochemical sensors based on electrogenerated chemiluminescence (ECL) emission. The research illustrated in this dissertation is categorized into three sections. The first section describes ECL sensor based on chitosan-TiO2-CdSe/ZnS quantum dot (QD) composite. Enhancement of the QD ECL was achieved through the use of a co-reactant in the ECL system, and by incorporating titania (TiO2) sol-gel in the composite film. Detection of ascorbic acid and several phenolic compounds was performed with the developed composite via ECL quenching reaction. Results have also suggested that sensitivity of the sensor can be controlled with adjustments to the components of the composite. Secondly, ECL of lucigenin at mesoporous Pt electrode was thoroughly investigated, and its biosensing application to superoxide dismutase (SOD) was demonstrated. The enlarged surface area of the fabricated mesoporous Pt was calculated and compared with a bare Pt electrode. The mechanism of lucigenin ECL at the surface of the mesoporous Pt electrode was proposed. From ECL quenching reaction with lucigenin and SOD, detection of SOD was performed, and the developed ECL sensor showed excellent sensitivity and selectivity towards SOD. Lastly, non-enzymatic glucose detection method with luminol ECL at mesoporous Pt electrode was demonstrated. The mesoporous Pt electrode produced highly enhanced luminol ECL, glucose detection was performed with ECL quenching reaction. The mesoporous Pt electrode showed high sensitivity and selectivity towards glucose without the use of an enzyme.

Phenylethynypyrene derivatives : synthesis, photophysical and electrochemical studies

이연옥 Graduate School, Korea University 2014 국내박사

Despite the remarkable developments in the past decade, the design of new high-performance semiconductors and a better understanding of the relationship between molecular structure and device properties are still the major challenges in modern molecular electronics. With this purpose in mind, a great effort has been devoted to the development of pyrene based molecules for electronic applications during Ph. D course. A strategy for enhancement of electrogenerated chemiluminescence and radical stability by peripheral multi-donors on alkynylpyrenes is described (Chapter 1). The five D-pi-A compounds were chosen according to the number and substituent position of peripheral donor moieties. The electrochemical instability of pyrene is improved by increasing the number of substituents of pheripheral DMA ethynyl. A series of tetrakis(ethynyl)pyrenes functionalized with N,N-dimethylaniline and 1-(trifluoromethyl)benzene as a peripheral electron donor and electron acceptor was dealt with in chapter 2. The redox peak reversibility depends on the number of peripheral donor and acceptors appended to tetrakis(ethylnyl)pyrenes as well as on their substitution pattern as revealed by cyclicvoltametric studies. The photophysical and electrochemical properties have been supported by the density functional theory (DFT) based calculation. In Chapter 3, a weakly donating group (n-propyl) has been used as a substituent at the para-position of the phenyl group for a series of phenylethynylpyren derivatives where the number of phenylethynyl peripheral arms appended to the pyrene core is varied. This system markedly improved the concurrently greatly improved electrogenerated chemiluminescence (ECL). Density functional theory (DFT)-based theoretical calculations supported the associated photohysical and electrochemical properties of the series compounds. The 1,3,6,8-tetrasubstituted pyrene in different molecular organizations from chapter 2 was also investigated in chapter 4. In this section, I suggest that intramolecular charge transfer (ICT) could cause to lower the efficiency of the electrogenerated luminescence. In this part, I designed and synthesized fluorene-based fluorescence imaging probe for detecting amyloid beta plaques in brain. The fluorescent probes Flu-VA contain a nitrogen donor group that is connected to a fluorene containing water solubilizing groups. The probe showed remarkable promise for the optical imaging of A aggregates. In addition, the stained A plaques exhibit fluorescence change in vivo mice.

[Ru(bpy)_(3)^(2+)] 전기화학발광(ECL)을 이용한 biogenic Amine류의 CE 검출법 개발

허연 연세대학교 대학원 2003 국내석사

본 연구는 모세관 전기이동법(Capillary electrophoresis, CE)을 이용하여 Amine기를 포함한 생체활성을 갖는 신경전달물질성 약물을 선택적이면서 고감도로 검출하기 위한 방법으로 sheath flow reactor에서 Tris(2,2'-bipyridine)ruthenium(II[Ru(bpy)_(3)^(2+)] 전기화학발광(ECL)을 이용하여 시료를 검출하였다. 후-컬럼 혼합 방법(post-column mixing method)를 적용하여, amine류인 phenothiazine을 특별한 유도체화 과정을 거치지 않고, 산화제를 이용해 산화된 Ru(bpy)_(3)^(2+)의 화학발광(CL)에 의한 검출특성을 연구 하였다. 전기적인 산화를 위해 흐름셀(flow cell)을 직접 제작하였고, 셀에 전극을 구성하여 Ru(bpy)_(3)^(2+)용액이 반응 용기로 이동되어 오면 전극에 가해진 1.3V의 전압에 의해 즉시 Ru(bpy)_(3)^(2+)로 산회되도록 장치를 고안하였다. 흐름셀을 통해서 산화된 Ru(bpy)_(3)^(2+)는 컬럼을 통해 분리된 시료와 반응하여 610mm의 오렌지 빛을 발생시키는데 이를 PMT(photo multiplier tube)로 검출하였다. 전기화학발광은 pH 6.0 sheath flow 속도는 1mm/s (3.6ml/min), Ru(bpy)_(3)^(2+)농도는 0.5 mM의 최적화된 조건하에서 산화상태의 Ru(bpy)_(3)^(2+)가 분석물과 반응하여 화학발광을 발생하고 그 결과 phenothiazine류의 경우 1∼20fmol까지 검출 가능하였다. 이때 발생하는 빛의 양은 분석물의 농도에 비례하게 된다. 또한 실제 시료인 인뇨(human urine)매질 하에서도 특별한 전처리 과정을 거치지 않고, 검출이 가능함을 확인할 수 있었다. 본 연구를 통해 CE^(-)Ru(bpy)_(3)^(2+)ECL을 이용한 3차 alkylamine류를 선택적이면서도 고감도로 검출할 수 있었다. 이러한 과정을 통해 개발된 ECL검출법은 여러 생리활성 물질의 특성 확인과 검출, 약물의 모니터링이나 생체 약물의 오용도 검사 등에 중요하게 응용될 수 있을 것으로 기대된다. The unique electrogenerated chemiluminescence(ECL) detection for capillary electrophoresis(CE) has been developed based on the Ru(bpy)_(3)^(2+) ECL reaction with sheath flow reactor. Studies are done post-column addition of Ru(bpy)_(3)^(2+) incorporated in the mobile phase. Ru(bpy)_(3)^(2+)-based ECL detection can be used to detect most amines without derivatization, thus facilitating the optimization of the CE separation process independent of the detection method. For this method, separated analytes are mixed at a sheath flow cuvette with a Ru(bpy)_(3)^(2+) stream and combined solution is then delivered to the detection cell. On the electrode surface of cell, Ru(bpy)_(3)^(2+)is oxidized to Ru(bpy)_(3)^(2+) by applied potential of 1.3V which reacts with the analyte and then emits the light of 610nm. Several optimized ECL conditions were experimentally detemined because ECL intensity was affected by pH, sheath flow rate, concentration. Sheath flow cell reactors afford sensitive detection in spite of very short reaction times. The sheath flow post column reactor reported here has achieved detection limits as low as fmol level with S/N of 3. In addition the determination of phenothiazine derivatives in human urine sample was performed by CE-ECL.