Selective C–C bond formation from rhodium-catalyzed C–H activation reaction of 2-arylpyridines with 3-aryl-2 <i>H</i> -azirines

Baek, Yonghyeon,Kim, Jinwoo,Hyunseok Kim,Jung, Seung Jin,Ryu, Ho,Kim, Suyeon,Son, Jeong-Yu,Um, Kyusik,Han, Sang Hoon,Seo, Hyung Jin,Heo, Juyoung,Lee, Kooyeon,Baik, Mu-Hyun,Lee, Phil Ho Royal Society of Chemistry 2019 Chemical Science Vol.10 No.9

<▼1><P>A novel method for the synthesis of acylmethyl-substituted 2-arylpyridine derivatives using 3-aryl-2<I>H</I>-azirines was developed.</P></▼1><▼2><P>A novel method for the synthesis of acylmethyl-substituted 2-arylpyridine derivatives using 3-aryl-2<I>H</I>-azirines was developed by exploring a prototype reaction using DFT-calculations and carrying out targeted experiments guided by the calculated mechanism. 2<I>H</I>-Azirine was initially hypothesized to ring-open at the metal center to furnish familiar metal nitrene complexes that may undergo C–N coupling. Computational studies quickly revealed and prototype experimental work confirmed that neither the formation of the expected metal nitrene complexes nor the C–N coupling were viable. Instead, azirine ring-opening followed by C–C coupling was found to be much more favorable to give imines that readily underwent hydrolysis in aqueous conditions to form acylmethyl-substituted products. This new method was highly versatile and selective toward a wide range of substrates with high functional group tolerance. The utility of the new method is demonstrated by a convenient one-pot synthesis of biologically relevant heterocycles such as pyridoisoindole and pyridoisoqunolinone.</P></▼2>

Efficient Development of Stable Recombinant Chinese Hamster Ovary (rCHO) Cell Lines to Produce Antibodies by Using Dimethyl Sulfoxide (DMSO) in Electroporation

( Juyoung Byun ),( Sena Yoon ),( Yunji Jeong ),( Uitaek Oh ),( Sujin Cho ),( Jeongsoo Park ),( Yongsu Jeong ),( Kwanghee Baek ),( Jaeseung Yoon ) 한국미생물 · 생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.1

Development of stable rCHO cell lines is still time consuming and labor intensive, although it is a critical step in the commercial development of recombinant antibodies. The current work demonstrates, for the first time, that electroporation of CHO cells with DMSO can enhance stable expression of recombinant antibodies in rCHO cells. Electroporation with DMSO resulted in an average 3.7-fold and 2.8-fold increases in expression levels of aflibercept and pembrolizumab, respectively, in pools of stable rCHO cells. It also resulted in an average of 2.2-fold and 2.6-fold increases in the expression of aflibercept and pembrolizumab, respectively, in single-cell derived rCHO clones. Simple batch cultures of rCHO cell clones with the highest expression produced 1.0 g/l for aflibercept and 1.4 g/l for pembrolizumab without a time-consuming gene amplification process. Electroporation with DMSO also shortened the development of rCHO cell lines to 2-3 months, allowing rapid establishment of stable rCHO cell lines with a desirable expression level antibodies.

A critical role of amphiphilic polymers in organic-inorganic hybrid sol-gel derived gate dielectrics for flexible organic thin-film transistors

Baek, Yonghwa,Li, Xinlin,Kim, Nahae,Park, Chan Eon,An, Tae Kyu,Kim, Juyoung,Kim, Se Hyun The Royal Society of Chemistry 2019 Journal of materials chemistry. C, Materials for o Vol.7 No.37

<P>The sol-gel method is a low-temperature, highly controllable and cost-effective method for producing homogeneous and high-quality ultrafine nanostructured thin films. Despite these advantages, sol-gel derived gate dielectrics have received little attention. Here, we synthesized a sol-gel derived organic-inorganic (O-I) hybrid gate dielectric (AGPTi) and demonstrated the stability and flexibility of organic thin-film transistors (OTFTs) made with it. The AGPTi film was simply fabricated from three conventional precursors, namely (3-glycidyloxypropyl)trimethoxysilane (GPTMS), propyltrimethoxysilane (PTMS), and titanium(iv) isopropoxide (TTiP), and a newly synthesized alkoxysilane-functionalized amphiphilic polymer (AFAP) under mild conditions (120 °C for 60 min). This research revealed several important benefits of including such an amphiphilic polymer in sol-gel derived O-I hybrid gate dielectrics: a considerable enhancement of sol stability; an ability to achieve a high-quality thin film with elaborate structures of small nanoclusters; and a dramatic improvement of adhesion, leakage current density of gate dielectrics, electrical stability and flexibility of devices. We expect this study to open up new applications for O-I hybrid materials in flexible electronics.</P>

A viscosity sensitive fluorescent dye for real-time monitoring of mitochondria transport in neurons

Baek, Yeonju,Park, Sang Jun,Zhou, Xin,Kim, Gyungmi,Kim, Hwan Myung,Yoon, Juyoung Elsevier 2016 Biosensors & Bioelectronics Vol.86 No.-

<P><B>Abstract</B></P> <P>We present here a viscosity sensitive fluorescent dye, namely thiophene dihemicyanine (TDHC), that enables the specific staining of mitochondria. In comparison to the common mitochondria tracker (Mitotracker Deep Red, MTDR), this dye demonstrated its unique ability for robust staining of mitochondria with high photostability and ultrahigh signal-to-noise ratio (SNR). Moreover, TDHC also showed high sensitivity towards mitochondria membrane potential (ΔΨ<SUB>m</SUB>) and intramitochondria viscosity change. Consequently, this dye was utilized in real-time monitoring of mitochondria transport in primary cortical neurons. Finally, the Two-Photon Microscopy (TPM) imaging ability of TDHC was also demonstrated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We presented here a viscosity sensitive dye that can remarkably improve signal-to-noise ratio for mitochondria specific staining. </LI> <LI> This dye showed high photostability, and high sensitivity to mitochondria membrane potential alteration. </LI> <LI> The dye was utilized in real-time monitoring mitochondria transport in primary cortical neurons. </LI> <LI> TPM imaging ability of the dye was also demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The viscosity sensitive fluorescent dye, which enable to specifically stain mitochondria with ultrahigh signal-to-noise ratio, was utilized in real-time monitoring mitochondria transport in primary cortical neurons.</P> <P>[DISPLAY OMISSION]</P>

Systematic Strategy for Designing Immidazolium Containing Precursors To Produce <i>N</i>-Heterocyclic Carbenes: A DFT Study

Baek, Kyung Yup,Jo, Ji Hye,Moon, Jong Hun,Yoon, Juyoung,Lee, Jin Yong American Chemical Society 2015 Journal of organic chemistry Vol.80 No.3

<P>A series of cationic <I>N</I>-heterocyclic carbene (NHC) precursors that can be utilized as fluorescent chemosensors for carbon dioxide capture were investigated by density functional theory (DFT) calculations. Activation energy barriers for the reactions of the cationic NHC precursors and hydrogen carbonate (HCO<SUB>3</SUB><SUP>–</SUP>) based on intrinsic reaction coordinate (IRC) profiles as well as proton affinity of the precursors were compared. The calculated proton affinity of 1-ethyl-3-methylimidazol-2-yliene was in good agreement with experimental one within the margin of error. We clarified main factors to lower the activation energy barrier based on the correlation among the number of <I>N</I>-heterocyclic functional group, aromatic ring size, and structural characteristics for the candidate compounds. On the basis of the results, it was verified that some of our model systems spontaneously generate NHCs without any specific catalyst.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/joceah/2015/joceah.2015.80.issue-3/jo502891z/production/images/medium/jo-2014-02891z_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jo502891z'>ACS Electronic Supporting Info</A></P>

NASA cFS 기반 다중화 구조의 INHA RoSAT 명령 및 데이터 처리계 구조 및 개발 환경

이주영(Juyoung Lee),유혜은(Hye-Eun Yoo),백준임(Junim Baek),유지수(Jisoo Yu),조용하(Yongha Jo),목성훈(Sung-Hoon Mok),최기영(Keeyoung Choi) 한국항공우주학회 2023 한국항공우주학회 학술발표회 논문집 Vol.2023 No.4

Zn²⁺-Triggered Amide Tautomerization Produces a Highly Zn²⁺-Selective, Cell-Permeable, and Ratiometric Fluorescent Sensor

Xu, Zhaochao,Baek, Kyung-Hwa,Kim, Ha Na,Cui, Jingnan,Qian, Xuhong,Spring, David R.,Shin, Injae,Yoon, Juyoung American Chemical Society 2010 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.132 No.2

<P>It is still a significant challenge to develop a Zn<SUP>2+</SUP>-selective fluorescent sensor with the ability to exclude the interference of some heavy and transition metal (HTM) ions such as Fe<SUP>2+</SUP>, Co<SUP>2+</SUP>, Ni<SUP>2+</SUP>, Cu<SUP>2+</SUP>, Cd<SUP>2+</SUP>, and Hg<SUP>2+</SUP>. Herein, we report a novel amide-containing receptor for Zn<SUP>2+</SUP>, combined with a naphthalimide fluorophore, termed <B>ZTRS</B>. The fluorescence, absorption detection, NMR, and IR studies indicated that <B>ZTRS</B> bound Zn<SUP>2+</SUP> in an imidic acid tautomeric form of the amide/di-2-picolylamine receptor in aqueous solution, while most other HTM ions were bound to the sensor in an amide tautomeric form. Due to this differential binding mode, <B>ZTRS</B> showed excellent selectivity for Zn<SUP>2+</SUP> over most competitive HTM ions with an enhanced fluorescence (22-fold) as well as a red-shift in emission from 483 to 514 nm. Interestingly, the <B>ZTRS</B>/Cd<SUP>2+</SUP> complex showed an enhanced (21-fold) blue-shift in emission from 483 to 446 nm. Therefore, <B>ZTRS</B> discriminated in vitro and in vivo Zn<SUP>2+</SUP> and Cd<SUP>2+</SUP> with green and blue fluorescence, respectively. Due to the stronger affinity, Zn<SUP>2+</SUP> could be ratiometrically detected in vitro and in vivo with a large emission wavelength shift from 446 to 514 nm via a Cd<SUP>2+</SUP> displacement approach. <B>ZTRS</B> was also successfully used to image intracellular Zn<SUP>2+</SUP> ions in the presence of iron ions. Finally, we applied <B>ZTRS</B> to detect zinc ions during the development of living zebrafish embryos.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2010/jacsat.2010.132.issue-2/ja907334j/production/images/medium/ja-2009-07334j_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja907334j'>ACS Electronic Supporting Info</A></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja907334j'>ACS Electronic Supporting Info</A></P>

Naphthoimidazolium based ratiometric fluorescent probes for F⁻ and CN⁻, and anion-activated CO₂ sensing

Kwon, Nahyun,Baek, Gain,Swamy, K.M.K.,Lee, Minji,Xu, Qingling,Kim, Youngmee,Kim, Sung-Jin,Yoon, Juyoung Applied Science Publishers 2019 Dyes and pigments Vol.171 No.-

<P><B>Abstract</B></P> <P>The results of the current study show that fluoride and cyanide recognition by two naphthoimidazolium derivatives can be applied to CO<SUB>2</SUB> sensing. Among various anions, only fluoride and cyanide promote changes in absorption and fluorescence wavelegnth maxima of the naphthoimidazolium derivative in CH<SUB>3</SUB>CN. The changes are attributed to (C–H)<SUP>+</SUP>--anion<SUP>-</SUP> ionic hydrogen bonding interactions between the conjugated imidazolium salts and these anions. Especially important is the observations that the fluorescence emission maxima of the naphthoimidazolium derivative at 465 nm undergo hysochromic shifts to 375 nm upon addition of fluoride and cyanide exclusively. The naphthoimidazolium derivatives undergo highly selective changes in their fluoerecence maximum from 465 nm to 375 nm upon addition of CN<SUP>−</SUP> even when 2% water is present in the CH<SUB>3</SUB>CN solution. Moreover, exposure of the solution of CN<SUP>−</SUP> activated naphthoimidazolium derivative to CO<SUB>2</SUB> promotes a red shift of emission maximum back to 465 nm. The results demonstrate that the naphthoimidazolium derivatives can be utilized for anion activated ratiometric sensing of CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The probe <B>1</B> and <B>2</B> display selective and ratiometric fluorescence changes upon addition of F<SUP>−</SUP> and CN<SUP>−</SUP>. </LI> <LI> Naphthoimidazoliums of <B>1</B> and <B>2</B> can play dual roles as fluorophores and ionic hydrogen bonding donors. </LI> <LI> Anion-activated ratiometric sensing of CO<SUB>2</SUB> is demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electronic relaxation dynamics of PCDA-PDA studied by transient absorption spectroscopy

Joung, Joonyoung F.,Baek, Junwoo,Kim, Youngseo,Lee, Songyi,Kim, Myung Hwa,Yoon, Juyoung,Park, Sungnam The Royal Society of Chemistry 2016 Physical Chemistry Chemical Physics Vol.18 No.33

<P>Photo-curable polymers originating from 10,12-pentacosadiynoic acid (PCDA-PDA) are commonly used polydiacetylenes (PDAs). PCDA-PDA exhibits thermochromic properties undergoing a unique colorimetric transition from blue to red as the temperature is increased from low to high. In this work, we have carefully studied the temperature-dependent optical properties of PCDA-PDA by using UV-visible absorption, FTIR, Raman, and transient absorption (TA) spectroscopy in combination with quantum chemical calculations. Temperature-dependent UV-visible absorption spectra indicate that PCDA-PDA exhibits reversible thermochromic properties up to 60 degrees C and its thermochromic properties become irreversible above 60 degrees C. Such distinct thermochromic properties are also manifested in TA signals so that the electronically excited PCDA-PDA relaxes to the ground state via an intermediate state at 20 degrees C (blue form) but it relaxes directly back to the ground state at 80 degrees C (red form). The electronic relaxation dynamics of PCDA-PDA are comprehensively analyzed based on different kinetic models by using the global fitting analysis method. The intermediate state in the blue form of PCDA-PDA is clearly found to be responsible for fluorescence quenching. FTIR and Raman spectroscopy and quantum chemical calculations confirm that the H-bonds between the carboxylic acid groups in PCDA-PDA are broken at high temperatures leading to an irreversible structural change of PCDA-PDA.</P>

Selective fluorescent recognition of Zn²⁺ by using chiral binaphthol-pyrene probes

Shirbhate, Mukesh Eknath,Jeong, Yerin,Ko, Gyeongju,Baek, Gain,Kim, Gyoungmi,Kwon, Yong-Uk,Kim, Kwan Mook,Yoon, Juyoung Elsevier 2019 Dyes and pigments Vol.167 No.-

<P><B>Abstract</B></P> <P>The bis-binaphthol-pyrene derivative <B>1</B> (R isomer) and 2 (S isomer) selectively sense Zn<SUP>2+</SUP> by undergoing a reversible fluorescent emission enhancement at 550 nm. Moreover, upon addition of Zn<SUP>2+</SUP>, the magnitude of the peak in the CD spectrum of <B>1</B> at 289 nm increases and the intensity of the peak at 272 nm decreases. Opposite changes were observed for <B>2</B> upon the addition Zn<SUP>2+</SUP>. The distinctive fluorescence and ratiometric CD spectral changes are attributed to a change in the dihedral angle between the binaphthol groups in <B>1</B> and 2 caused by Zn<SUP>2+</SUP> binding. Probe <B>1</B> was further employed to image Zn<SUP>2+</SUP> in cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The bis-binaphthol-pyrene derivative <B>1</B> and <B>2</B> selectively sense Zn<SUP>2+</SUP>. </LI> <LI> The distinctive fluorescence and ratiometric CD spectral changes were observed upon the addition of Zn<SUP>2+</SUP>. </LI> <LI> Probe <B>1</B> (R isomer) and <B>2</B> (S isomer) displayed opposite CD spectral changes with Zn<SUP>2+</SUP>. </LI> <LI> Probe <B>1</B> was employed to image Zn<SUP>2+</SUP> in cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>