Tertiary Assembly Structures of Molecular Cages with Superb-Hierarchy Based on Triple Stranded Helicates

( Nguyen Quoc Khuong Anh ),( Maiduyhien ),유효종 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Rational design of molecular platforms with structural hiearachy and complexity based on the coordination-driven multilevel assembly of each fundamental units is of considerable interest. Notably, discrete molecular cages could be developed from well-organized secondary supramolecules through tertiary assembly process. In this work, a variety of tertiary discrete molecular cages with distinct functionalities resulting from the hierarchical arrangement of triple-stranded supramolecular helicates is reported. The discrete molecular cages show significantly enhanced CO₂ adsoprtion properties in comparison with separate triple-stranded helicates.

Metal-Ion Tuning in Triple-Stranded Helicate-based Metallosupramolecules and Their Higher-Order Polymeric Assemblies

( Maiduyhien ),유효종,강필재 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

One of the most widely used synthetic approaches is the utilization of the molecular symmetry principle to assemble multiple ligands and metallic centers in a preferred manner. Variation of metal ions can be helpful to understand the importance of symmetry for the generation of hierarchical molecular platforms. The synthesis and characterization of isostructural supramolecular helicates, [M₈(PDA)₆(AIP)₃(DMF)_6-x(H₂O)_x] (M=Ni (1), Co (2), and Mn (3); PDA=2,6-pyridinedicarboxylate; AIP=5-aminoisophthalate; x=0 for 1, and x=4 for 2 and 3) are reported Despite the disparity in the ionic radii and distinct coordination-geometry preferences of Co²⁺, Ni²⁺, and Mn²⁺, all metals engaged in the assembly with the heteroleptic ligands in the same manner to form isostructural supramolecular helicates. In addition, 1, 2, and 3 can be used as supramolecular modules for the construction of higher-order polymeric structures.

Metal-Ion Tuning in Triple-Stranded Helicate-based Metallosupramolecules and Their Higher-Order Polymeric Assemblies

( Maiduyhien ),유효종 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Combination of mixed ligands in a given coordination structure leads to coordination-driven assembly with improved structural complexity and functional diversity. Molecular symmetry principle to assemble multiple ligands and specific metallic centers in a preferred manner is the key. Herein, we describe the synthesis and characterization of isostructural supramolecular helicates, [M₈(PDA)₆(AIP)₃(DMF)_6-x(H₂O)_x] (M=Ni (1), Co (2), and Mn (3); PDA=2,6-pyridinedicarboxylate; AIP=5-aminoisophthalate; x=0 for 1, and x=4 for 2 and 3). Despite the disparity in the ionic radii and distinct coordination-geometry preferences of Co²⁺, Ni²⁺, and Mn²⁺, all metal centers engaged in the assembly with the heteroleptic ligands to form isostructural supramolecular helicates. In addition, 1, 2, and 3 can be employed as conceptual supramolecular modules for the construction of higherorder polymeric structures via the coordination with extra metal ions.

Meshing performance investigations of involute worm and helical gear drive based on counterpart rack

Binbin Lu,Yonghong Chen,Shi-xuan Li,Bingkui Chen 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

Due to the involute worm and helical gear drive is different from the parallel shaft helical gear drive and the worm drive, the plane meshing theory and the space enveloping principle cannot be directly applied for this worm drive when the meshing analysis is performed, there has been no good analysis method to accurately calculate the meshing situation. To satisfy the increasing requirements of low-noise and long-lifetime in the service robots and the modern intelligent house systems, especially the intelligent shading system in the modern intelligent house system, a novel meshing performance analysis method is proposed for the involute worm and helical gear drive based on the counterpart rack. By calculating the contact line between the counterpart rack and helical gear and the contact line between the counterpart rack and involute worm, we can get the contact point of involute worm and helical gear finally. This novel meshing performance analysis makes it possible to use the plane meshing theory and the space enveloping principle to analyze involute worm and helical gear drive. The meshing relationship between the involute worm and the counterpart rack, as well as the counterpart rack and the helical gear are presented, and the computational model of contact ratio and contact ellipse are obtained through the counterpart rack. The mathematic model for the instantaneous contact point and contacts trace of the worm drive with different assembly errors is established, and the meshing performances are investigated through the numerical analysis, simulation analysis and performance testing. The results show that this worm drive is insensitively to the assembly errors, and it is beneficial for reducing the vibrationnoise and extending the service life. This theoretical research provides theoretical support for further optimizing the vibration and noise of involute worm and helical gear drive and improving the fatigue life.

Self-assembly of supramolecular polymers into tunable helical structures

Kim, Ho-Joong,Lim, Yong-Beom,Lee, Myongsoo Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of polymer science Part A, Polymer chemist Vol.46 No.6

<P>There is growing interest in the design of synthetic molecules that are able to self-assemble into a polymeric chain with compact helical conformations, which is analogous to the folded state of natural proteins. Herein, we highlight supramolecular approach to the formation of helical architectures and their conformational changes driven by external stimuli. Helical organization in synthetic self-assembling systems can be achieved by the various types of noncovalent interactions, which include hydrogen bonding, solvophobic effects, and metal-ligand interactions. Since the external environment can have a large influence on the strength and configuration of noncovalent interactions between the individual components, stimulus-induced alterations in the intramolecular noncovalent interactions can result in dynamic conformational change of the supramolecular helical structure thus, driving significant changes in the properties of the materials. Therefore, these supramolecular helices hold great promise as stimuli-responsive materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1925–1935, 2008</P> <B>Graphic Abstract</B> <P>This highlight focuses on the supramolecular approaches to constructing helical architectures and their stimuli-responsive dynamic conformational changes. The stimuli-responsive, reversible, and dynamic properties of supramolecular helices provide a prospect of using them as smart materials. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.] <img src='wiley_img/0887624X-2008-46-6-POLA22569-gra001.gif' alt='wiley_img/0887624X-2008-46-6-POLA22569-gra001'> </P>

Supramolecular Helical Columns from the Self-Assembly of Chiral Rods

Ryu, Ja-Hyoung,Tang, Lijun,Lee, Eunji,Kim, Ho-Joong,Lee, Myongsoo WILEY-VCH Verlag 2008 Chemistry Vol.14 No.3

<P>Chiral-bridged rod molecules (CBRs) that consisted of bis(penta-p-phenylene) conjugated to an opened or closed chiral bridging group as a rigid segment and oligoether dendrons as flexible segments were synthesized and characterized. In the bulk state, both molecules self-assemble into a hexagonal columnar structure, as confirmed by X-ray scatterings and transmission electron microscopy (TEM) observations. Interestingly, these structures display opposite Cotton effects in the chromophore of the aromatic unit in spite of the same chirality (R,R) of the chiral bridging groups. The molecules were observed to self-assemble into cylindrical micellar aggregates in aqueous solution, as confirmed by light scattering and TEM investigations, and exhibit intense signals in the circular dichroism (CD) spectra, which are indicative of one-handed helical conformations. The CD spectra of each molecule showed opposite signals to each other, which were similar to those in the bulk. Notably, when the opened CBR was added to a solution of closed CBRs up to a certain concentration, the CD signal of the closed CBR was amplified. This implies that both molecules co-assemble into a one-handed helical structure because the opened chiral bridge is conformationally flexible, which is inverted to co-assemble with the closed CBR. These results demonstrate that small structural modifications of the chiral moiety can transfer the chiral information to a supramolecular assembly in the opposite way.</P> <B>Graphic Abstract</B> <P>Chiral template: When an opened chiral-bridged rod molecule was added to a solution of closed chiral-bridged rod molecules, both molecules co-assemble into a one-handed helical structure owing to conformational flexibility of the opened chiral-bridged rod molecule (see picture). <img src='wiley_img/09476539-2008-14-3-CHEM200701080-content.gif' alt='wiley_img/09476539-2008-14-3-CHEM200701080-content'> </P>

Stabilization of an α Helix by β-Sheet-Mediated Self-Assembly of a Macrocyclic Peptide

Lim, Yong-beom,Moon, Kyung-Soo,Lee, Myongsoo WILEY-VCH Verlag 2009 Angewandte Chemie. international edition Vol.48 No.9

<P>Protein roll call: Peptide-based building blocks, in which both an α-helix-forming segment and a β-sheet segment are located within a single macrocyclic structure, self-assemble into α-helix-decorated artificial proteins. This approach provides a starting point for developing artificial proteins that can modulate α-helix-mediated interactions occurring in a multivalent fashion. <img src='wiley_img_2010/14337851-2009-48-9-ANIE200804665-content.gif' alt='wiley_img_2010/14337851-2009-48-9-ANIE200804665-content'> </P> <B>Graphic Abstract</B> <P>Protein roll call: Peptide-based building blocks, in which both an α-helix-forming segment and a β-sheet segment are located within a single macrocyclic structure, self-assemble into α-helix-decorated artificial proteins. This approach provides a starting point for developing artificial proteins that can modulate α-helix-mediated interactions occurring in a multivalent fashion. <img src='wiley_img_2010/14337851-2009-48-9-ANIE200804665-content.gif' alt='wiley_img_2010/14337851-2009-48-9-ANIE200804665-content'> </P>

Lanthanitin: A Chiral Nanoball Encapsulating 18 Lanthanum Ions by Ferritin-Like Assembly

Jeong, Kyung Seok,Kim, Young Shin,Kim, Yun Ju,Lee, Eunsung,Yoon, Ji Hye,Park, Won Hwa,Park, Young Woo,Jeon, Seung-Joon,Kim, Zee Hwan,Kim, Jaheon,Jeong, Nakcheol WILEY-VCH Verlag 2006 Angewandte Chemie Vol.45 No.48

<B>Graphic Abstract</B> <P>A chiral supramolecule, obtained by self-assembly of 24 chiral ditopic carboxylate ligands, 18 La ions, and two carbonate anions, has been dubbed lanthanitin because of its structural resemblance to ferritin. The picture shows the molecular structure of one enantiomer of lanthanitin. Color code: La blue, carbonate C green, C gray, O red; H omitted. <img src='wiley_img/14337851-2006-45-48-ANIE200603622-content.gif' alt='wiley_img/14337851-2006-45-48-ANIE200603622-content'> </P>

1P-552 Rational Design of Hydroxyl-Functionalized Cobalt Triple-Stranded Helicate and its Higher-Order Assembly into Polymeric Structures

이인미,( Maiduyhien ),유효종 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Coordination-driven metallosupramolecules with functional multiplicity are of considerable importance in a variety of applications. The basic structural information of a cobalt triple-stranded helicates (CoTSHs) is the helical arrangement of two tetranuclear cobalt clusters and three isophthalate ligands. The introduction of desired functional moieties (hydroxyl groups) at specific positions on CoTSHs is feasible by using hydroxyl-isophthalate ligands (OH-PTA). Herein, the hydroxyl- functionalized CoTSH, [Co₈(PDA)₆(OH-PTA)₃(DMF)₆] (1) (PDA = 2,6-pyridinedicarboxylate, OH-PTA = 5-hydroxyl isophthalate, DMF = dimethylformamide) is isolated in the presence of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) as a base. Upon using excessive amount of cobalt precursor and changing base used triethylamine (TEA), a higher-order one-dimensional polymer (2) with superb-hierarchical structure is generated.

조립 오차를 고려한 전동차용 헬리컬기어의 굽힘강도 평가

이동형(D. H. Lee),최돈범(D. B. Choi),강성웅(S. W. Kang),최하영(H. Y. Choi) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월

대량의 승객을 수송하는 철도차량에서 감속기는 모터의 동력을 차축으로 전달하기 위한 핵심 장치이고, 기어 및 케이스, 베어링, 베어링 하우징 등의 부품으로 구성되어 있다. 여러 부품 중 기어는 감속기에서 가장 중요한 부품 중 하나이고, 피니언 및 기어는 고속 및 고부하를 고려하여 설계, 제작하고 있지만, 제작 시 기어 및 케이스의 가공오차와 조립 시 조립 오차로 인하여 기어의 편접촉이 발생하기 때문에 감속기의 과도한 진동 또는 기어의 이빨 파손, 치면손상 등이 발생하는 사례가 있다. 따라서 이와 같은 가공 및 조립 오차 등 각종 오차를 고려한 기어의 강도 평가는 철도차량 안전 운행을 위해 확보해야 할 중요 기술 중 하나이다. 본 연구에서는 전동차용 헬리컬기어를 대상으로 3 차원 유한요소해석 모델을 구축하고, 하중 전달 시 접촉 위치 변화에 따른 기어의 굽힘응력 해석 방법을 정립하였고, 기존 강도계산 기준과 비교하여 해석의 타당성을 검증하였다. 국제규격을 이용한 기어의 굽힘강도 계산에는 하중계수를 적용하는 방법으로 가공 또는 조립오차에 대한 고려를 하고 있지만, 실제 제작시 오차의 범위를 설정하기 어렵다. 따라서 구축된 모델을 이용하여 가공 및 조립 시 발생하는 오차인 중심거리 오차, 축의 평행도 오차 등에 따른 기어의 굽힘응력 변화를 분석하였다.