• Bulletin of the Korean Chemical Society
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• 제24권4호
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• pp.479-483
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• 2003

The reactions of 2,5-bis(ethynyldimethylsilyl)thiophene (1) with aromatic dihalides(1,4-dibromobenzene, 4,4'- dibromobiphenyl, 9,10-dibromoanthracene, 2,5-dibromopyridine, 2,5-dibromothiophene, and 2,6-diiodo-4- nitroaniline) were carried out in the presence of a $[(PPh_3)_2PdCl_2]$-CuI catalyst in refluxing triethylamine to give poly{[2,5-bis(ethynylenedimethylsilylene)thienylene](arylene)} (2-7) with molecular weights of 2200-7400. The oligomers reveal characteristic absorption in the UV/visible region. The thermal behavior of 2-7 was examined by thermogravimetric analysis in an argon atmosphere.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2099-2104
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• 2013

We present here an efficient and simple method for preparation of highly active Pd heterogeneous catalyst (CNT-Pd), specifically by reaction of dichlorobis(triphenylphosphine)palladium ($Pd(PPh_3)_2Cl_2$) with thiolated carbon nanotubes (CNTs). The as-prepared CNT-Pd catalysts demonstrated an excellent catalytic activity for the carbon-carbon (C-C) cross-coupling reactions (i.e. Suzuki, Stille, and decarboxylative coupling reactions) under mild conditions. The CNT-Pd catalyst could easily be removed from the reaction mixture; additionally, in the decarboxylative coupling of iodobenzene and phenylpropiolic acid, it showed a six-times recyclability, with no loss of activity. Moreover, once its activity had decreased by repeated recycling, it could easily be reactivated by the addition of phosphine ligands. The remarkable recyclability of the decarboxylative coupling reaction is attributable to the high degree of dispersion of Pd catalysts in CNTs. Aggregation of the Pd catalysts is inhibited by their strong adhesion to the thiolated CNTs during the chemical reactions, thereby permitting their recycling.

• Mycobiology
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• 제49권3호
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• pp.285-293
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• 2021

Polylactic acid (PLA) and polycaprolactone (PCL) are commercially available bioplastics that are exploited worldwide, and both are biodegradable. The PLA and PCL polymer-degrading activity of 30 fungal strains that were isolated from terrestrial environments were screened based on the formation of a clear zone around fungal colonies on agar plates containing emulsified PLA or PCL. Among them, five strains yielded positive results of biodegradation. Strains Korean Agricultural Culture Collection (KACC) 83034BP and KNUF-20-PPH03 exhibited PCL degradation; two other strains, KACC 83035BP and KNUF-20-PDG05, degraded PLA; and the fifth strain, KACC 83036BP, biodegraded both tested plastics. Based on phylogenetic analyses using various combinations of the sequences of internal transcribed spacer (ITS) regions, RPB2, LSU, CAL, and b-TUB genes, the above-mentioned strains were identified as Apiotrichum porosum, Penicillium samsonianum, Talaromyces pinophilus, Purpureocillium lilacinum, and Fusicolla acetilerea, respectively. Based on our knowledge, this is the first report on (i) plastic biodegraders among Apiotrichum and Fusicolla species, (ii) the capability of T. pinophilus to degrade biodegradable plastics, (iii) the biodegradative activity of P. samsonianum against PCL, and (iv) the accurate identification of P. lilacinum as a PLA biodegrader. Further studies should be conducted to determine how the fungal species can be utilized in Korea.

• Bulletin of the Korean Chemical Society
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• 제8권3호
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• pp.179-183
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• 1987

Reactions of $Rh(ClO_4)(CO)(AsPh_3)_2$ with unsaturated nitriles and aldehyde, L, produce a series of new cationic rhodium (I) complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ (L = $CH_2$ = CHCN, $CH_2$ = C($CH_3$)CN, trans-$CH_3CH$ = CHCN, $CH_2$ = CH$CH_2$CN, trans-$C_6H_5CH$ = CHCN, and trans-$C_6H_5CH$ = CHCHD) where L are coordinated through the nitrogen and oxygen, respectively but not through the ${\pi}$-system of the olefinic group. Dissociation constants for the reaction, $[RhL(CO)(AsPh_3)_2]ClO_4$ $\rightleftharpoons$ $Rh(ClO_4)(CO)(AsPh_3)_2$ + L, have been measured to be $1.20{\times}10^{-4}$ M (L = $CH_2$ = CHCN), $1.05{\times}10^{-4}$ M (L = $CH_2$ = C($CH_3$)CN, $3.26{\times}10^{-5}$ M (L = trans-$CH_3$CH = CHCN) and $6.45{\times}10^{-5}$ M (L = $CH_2$ = CH$CH_2$CN) in chlorobenzene at $25^{\circ}C, and higher than those of triphenylphosphine complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ where L are the corresponding nitriles that are coordinated through the nitrogen atom. The differences in dissociation constants seem to be predominantly due to the differences in ${\Delta}H$ (not due to the differences in ${\Delta}S$). The weaker Rh-N (unsaturated nitriles) bonding in $AsPh_3$ complexes than in $PPh_3$ complexes (based on ${\Delta}H$ values) suggests that the unsaturated nitriles in 2∼5 are good ${\sigma}$-donor and poor ${\pi}$-acceptor.

• Bulletin of the Korean Chemical Society
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• 제15권11호
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• pp.990-996
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• 1994

New ferrocene-based chelate amines, $Fe[C_5H_4CH(Me)NMe_2]_2\;(3), \;Fe[C_5H-3(CH(Me)NMe_2)(PPh_2)-1,2]_2\;(4),\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(CN)NMe_2-1,2)\;(6),\;and\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(Me)NMe_2-1,2)$ (7) have been prepared. The reaction and the coordination chemistry of 4 and other related compounds (S,R)-(1-N,N-dimethylaminoethyl)-2-dicyclohexylphosphino)ferrocene (CPFA) and 1,1'-bis-(diphenylphosphino)ferrocene (BPPF) with $Rh_2(OAc)_4(MeOH)_2$ were investigated. The reaction of the chiral ligand (S,R)-CPFA forms a complex of the type (${\eta}^1$-(S,R)-CPFA-P)$_2Rh_2(OAc)_4$ (8) in which the ligand is coordinated to both rhodium centers in a monodentate fashion through phosphorus. In contrast, the bisphosphine analogues such as BPPF and 4 afford chelate complexes of the type (${\eta}^2-PP)Rh_2(OAc)_4$ (9 & 10) where both ligands act as a chelate bidentate to a single rhodium atom. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of 8 was determined by X-ray crystallography. Crystals are monoclinic, space group C2 (No. 5), with a=26.389 (3), b=12.942 (1), c=11.825 (1) A, ${\beta}$=111.22(1)$^{\circ}$, V=3964.7 (8) $A^3$, Z=4, and $D_{calc}$=1.58 g $cm^{-3}$. Two Rh(II) centers are bridged by four $AcO^-$ groups in the ${\eta}^1$ : ${\eta}^1$ mode across a Rh-Rh single bond, and octahedral coordination at Rh(1) and Rh(1') is completed by axially coordinating (S,R)-CPFA and a briding $AcO^-$, respectively.

• 대한화학회지
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• 제37권11호
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• pp.967-973
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• 1993

1,6-헥산디올과 1,7-헵탄디올과 같은 ${\alpha},{\omega}$-디올은 180$^{\circ}$C, 24시간, 촉매량의 루테늄 착물존재하에서 이차아민과 반응하여 좋은 수득율로 대응하는 생성물인 디아미노화합물이 얻어졌다. 디아미노화합물의 수득률은 ${\alpha},{\omega}$-디올과 이차아민의 몰비에 의해 영향을 받았으며, 또한 반응은 채택한 포스핀 배위자의 성질에의해 영향을 받았다. 한편으로 디옥산 용매내에서 루테늄-포스핀 촉매와 방향족 일차아민 및 1,2,6-헥산트리올을 180$^{\circ}$C, 3시간 반응시키면 선택적으로 1-치환-2-히드록시 과수소아제핀이 좋은 수득율로 주어졌다. 이 생성물의 선택적 합성은 두 개의 일차히드록시기가 보다 우선적으로 산화함을 보여주고 있다. 수득율은 방향족 아민의 파라-, 메타- 및 오르토 치환기의 순서에 따라 감소하였다.

• 미생물학회지
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• 제50권1호
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• pp.60-66
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• 2014

본 연구에서는 Lactobacillus brevis HLJ59 균주를 이용하여 오미자 당침액의 발효특성을 조사하였다. 발효에 따른 생균수와 PPH radical 소거활성, 환원력 및 SOD 유사활성을 조사하였다. 또한 오미자 당침액의 ACE 저해활성 및 Urease 저해활성을 조사하였다. 생균수의 경우 2배, 5배, 10배 희석액의 경우 $2.05{\pm}0.21{\times}10^8$, $6.31{\pm}0.56{\times}10^{11}$, $8.14{\pm}0.14{\times}10^9$으로 각각 조사되었으며, DPPH radical 소거활성은 2배, 5배, 10배 희석액의 경우 60.3%, 71.8%, 44.5%로 각각 조사되었다. 환원력은 2배, 5배, 10배 희석액의 경우 0.92, 1.19, 0.73 (700 nm에서의 OD값)로 각각 조사되었고, SOD 유사활성은 2배, 5배, 10배 희석액의 경우 50.4%, 53.7%, 33.4%로 각각 조사되었다. 그리고 ACE 저해활성 및 Urease 저해활성은 2배, 5배, 10배 희석액의 경우 47.4%, 78.2%, 56.4% 및 58.1%, 83.4%, 63.2%로 각각 조사되었다. 이상의 결과에서 오미자 당침 희석액 발효물은 우수한 항산화활성과 ACE 및 Urease 저해활성을 지님으로서 이를 기능성 식품소재로 활용할 수 있다고 사료된다.

• 한국응용곤충학회지
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• 제32권3호
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• pp.307-316
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• 1993

해충의 발생예찰자료의 분석에 있어서 지리자료처리체계의 활용 가능성을 검토하였다. 전국의 152개 병해충 발생예찰소의 해충 발생자료를 이용하여 해충지리적 분포정보를 집적하는 "데이터베이스" 체계를 SPANS(Spatial Analysis Systme)로 구축하였다. 구축된 "지리분포 데이터베이스"로부터 최근 10년간 이화명나방 발생량의 분포변동을 추적한 결과 일반계 품종이 확대 재배되기 시작한 80년대 중반터 고밀도 분포지가 급속히 확산됨을 볼 수 있었다. 또한 분포의 확산과 수축의 중심은 전북의 이리지역임이 확실하게 나타났다. 별멸구의 초기(7월초) 비래량의 분포를 비래후 온도조건과 결부시켜 후기(9월중)의 벼멸구 발생위험지역을 예측하는 시뮬레이션 모형을 구성하였다. 모형에 의해 추정된 벼멸구 발생위험지역을 예측하는 시뮬레이션 모형을 구성하였다. 모형에 의해 추정된 벼멸구 발생지의 분포도를 1990년 9월의 실재 발생분포도와 비교한 결과 경북 청도지역을 제외하고는 분포양상이 매우 유사하였다. 경사도, 고도, 재배작물 등의 분포도를 추정된 벼멸구 발생도와 함께 투시.분류(Overlay/Modeling)하는 기법을 사용한 결과 서남부지역의 벼멸구 국지적 발생위험지를 구분해 낼 수 있었다.