Browsing by Author "Chen, Hsin-Lung"

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Conformational Preferences and the Phase Stability of Fullerene Hexa-adducts
(2016-07-20)
Wu, San-Lien
;
Hong, Chen-Yang
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Wu, Kuan-Yi
;
Lan, Shih-Ting
;
Hsieh, Chou-Ting
Molecular conformation and the assembly structure determine the spatial arrangements of the constituent units and the functions of a molecule. Although, fullerene hexa-adducts (FHAs) have been known as functional materials with great versatility, their conformational preferences and phase stability remain a complicate issue. By choosing bithiophene (T-2) and dodecyl bithiophene (C12T2) as the peripheral units of FHA, and using microscopic, scattering and diffraction characterizations, our study reveals how the intramolecular interaction and environmental stimulus affects the conformational preferences and phase stability of FHAs.
Crystal structure and molecular packing of an asymmetric giant amphiphile constructed by one C-60 and two POSSs
(2014-08-18)
Lin, Ming-Champ
;
Hsu, Chih-Hao
;
Sun, Hao-Jan
;
Wang, Chien-Lung
;
Zhang, Wen-Bin
Based on our recent understanding and development of functionalized molecular nanoparticles (MNPs) as building blocks for constructing various giant molecules, we report our efforts on design and synthesis of an asymmetric giant amphiphile, diBPOSS-C-60, composed of one [60]fullerene (C-60) covalently linked with two isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS) MNPs. Its crystal structure and molecular packing were investigated. The compositional asymmetry between C-60 and BPOSS led to a "sandwich-layered" molecular packing scheme, where a single layer of C-60 is sandwiched between double BPOSS layers: a so-called "one-and-half-layered" structure. Within these layers, the molecules further organized into crystalline arrays. Interestingly, this compound can be viewed as size amplification of a class of atomically thin, two-dimensional layered transition metal dichalcogenides with the "one-and-half-layered" structure. 2014 Elsevier Ltd. All rights reserved.
Crystal structure and molecular packing of an asymmetric giant amphiphile constructed by one C-60 and two POSSs
(2014-08-18)
Lin, Ming-Champ
;
Hsu, Chih-Hao
;
Sun, Hao-Jan
;
Wang, Chien-Lung
;
Zhang, Wen-Bin
Based on our recent understanding and development of functionalized molecular nanoparticles (MNPs) as building blocks for constructing various giant molecules, we report our efforts on design and synthesis of an asymmetric giant amphiphile, diBPOSS-C-60, composed of one [60]fullerene (C-60) covalently linked with two isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS) MNPs. Its crystal structure and molecular packing were investigated. The compositional asymmetry between C-60 and BPOSS led to a "sandwich-layered" molecular packing scheme, where a single layer of C-60 is sandwiched between double BPOSS layers: a so-called "one-and-half-layered" structure. Within these layers, the molecules further organized into crystalline arrays. Interestingly, this compound can be viewed as size amplification of a class of atomically thin, two-dimensional layered transition metal dichalcogenides with the "one-and-half-layered" structure. 2014 Elsevier Ltd. All rights reserved.
Fractal aggregates of conjugated polymer in solution state
(2006-12-19)
Li, Yen-Cheng
;
Chen, Kuei-Bai
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Chen, Hsin-Lung
;
Hsu, Chain-Shu
;
Tsao, Cheng-Si
Semirigid conjugated polymers have received much scientific and technological interest due to their unique electrical and photonic semiconducting properties. Spectroscopic studies have indicated that these polymers underwent interchain aggregation in the solution state even at large dilution; however, the origin of this event and the structure of the resultant aggregates remained the crucial issues to be resolved. In the present study, we revealed that the interchain aggregation of a conjugated polymer, poly(2,3-diphenyl-5-hexyl-1,4-phenylenevinylene) (DP6-PPV), in solutions with chloroform and toluene generated network aggregates with the hydrodynamic radii of several micrometers. Small angle neutron scattering (SANS) demonstrated that the internal structure of these aggregates could be characterized by the mass fractal dimensions of 2.2-2.7. The networks were looser in chloroform but became highly compact in the poorer toluene solvent due to severe segmental association. Increasing the temperature alleviated the segmental association in toluene while largely retaining the mass fractal dimension of the aggregates. However, the interchain aggregation was never completely dissipated by the heating, suggesting the existence of two types of segmental association with distinct stability. The highly stable segmental association that could neither be solvated by chloroform nor be disrupted thermally in toluene was attributed to the d-d complex already present in the DP6-PPV powder used for the solution preparation. The chains tied firmly by this complex formed network aggregates in the solution and hence reduced the entropy of mixing of the polymer. In the poorer toluene solvent, further segmental association took place within the preexisting aggregates, making the networks more compact. This type of segmental association could be disrupted by moderate heating, and its occurrence was ascribed to the poor affinity of the aliphatic side chains of DP6-PPV for toluene.
Orientation Preferences of Interchain Stackings for Poly(3-hexylthiophene) Nanowires Prepared Using Template-Based Wetting Methods
(2018-06-01)
Jeng, Kai-Sheng
;
Chu, Chien-Wei
;
Liu, Chien-Liang
;
Jean, Woan-Mei
;
Chen, Hsin-Lung
Poly(3-hexylthiophene) (P3HT) nanowires have drawn great attention recently because of their unique properties that can be applied to optoelectronic devices such as conjugated polymer solar cells and organic field-effect transistors. There is still an urgent need, however, to study the fabrication and characterization of P3HT nanowires with controllable morphologies and molecular orientations. In this work, feasible routes are presented to fabricate P3HT nanowires using the solution wetting template method and the solvent-annealing-induced nanowetting in template (SAINT) method. The morphologies and chemical compositions of the P3HT nanowires prepared using these two methods are confirmed by scanning electron microscopy, transmission electron microscopy (TEM), and Raman spectroscopy. From the ultraviolet-visible spectroscopy and wide-angle X-ray scattering results, it is concluded that the degrees of the crystallinity and the orientation preferences of interchain stackings along the pore axis for the P3HT nanowires prepared by the SAINT method are higher than those prepared by the solution wetting template method.
PEGylation Site-Dependent Structural Heterogeneity Study of MonoPEGylated Human Parathyroid Hormone Fragment hPTH(1-34)
(2014-09-30)
Liu, Chih-Ying
;
Li, Xin
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Chen, Wen-Yih
;
Chang, Li-Chiao
;
Chen, Yi-Fan
The structures of C- and N-terminally monoPEGylated human parathyroid hormone fragment hPTH(1-34) as well as their unmodified counterparts, poly(ethylene glycol) (PEG) and hPTH(1-34), have been studied by small-angle neutron scattering (SANS). The scattering results show that free hPTH(1-34) in 100 mM phosphate buffer (pH 7.4) aggregates into clusters. After conjugation with PEG, the PEG-peptide conjugates self-assemble into a supramolecular core-shell structure with a cylindrical shape. The PEG chains form a shell around the hPTH(1-34) core to shield hPTH(1-34) from the solvent. The detailed structural information on the self-assembled structures is extracted from SANS using a model of the cylindrical core with a shell of Gaussian chains attached to the core surface. On the basis of the data, because of the charge-dipole interactions between the conjugated PEG chain and the peptide, the conjugated PEG chain forms a more collapsed conformation compared to free PEG. Moreover, the size of the self-assembled structures formed by the C-terminally monoPEGylated hPTH(1-34) is about 3 times larger than that of the N-terminally monoPEGylated hPTH(1-34). The different aggregation numbers of the self-assembled structures, triggered by different PEGylation sites, are reported. These size discrepancies because of different PEGylation sites could potentially affect the pharmacokinetics of the hPTH(1-34) drug.
Scattering Study of the Conformational Structure and Aggregation Behavior of a Conjugated Polymer Solution
(2009-04-21)
Li, Yen-Cheng
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Chen, Chun-Yu
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Chang, Ying-Xun
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Chuang, Pei-Ying
;
Chen, Jean-Hong
The conformational structure and the interchain aggregation behavior of a semirigid conjugated polymer bearing a decyl side chain, poly(2,3-diphenyl-5-decyl-1,4-phenylenevinylene) (DP10-PPV), in solutions with chloroform and toluene have been investigated by means of small-angle neutron scattering (SANS), static light scattering (SLS) and dynamic light scattering (DLS). The radius of gyration, persistence length, and the second virial coefficient of the polymer in dilute solution as determined by SLS were higher in chloroform than in toluene; consequently, the polymer assumed a more extended wormlike chain conformation in the former. The difference in the strength of interaction in the two solvents gave rise to contrasting aggregation behavior of the polymer in the semidilute regime. While only a minor fraction of the polymer underwent segmental association in chloroform, a considerable fraction of it formed clusters (microgels) with several micrometers in size in toluene. These clusters were further found to consist of sheetlike nanodomains. Compared with the DP-PPV bearing a shorter hexyl side chain, DP6-PPV, the aggregates of DP10-PPV in toluene were weaker as they could be easily disrupted by moderate heating. This was attributed to a lack of strong pi-pi interaction between the DP10-PPV segments due to the greater steric hindrance imposed by the longer decyl side chains.
Supramolecular structures of an amphiphilic hairy-rod conjugated copolymer bearing poly(ethylene oxide) side chain
(2009-07-01)
Liao, Shao-Ching
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Lai, Chia-Sheng
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Yeh, Di-Di
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Rahman, M. Habibur
;
Hsu, Chain-Shu
The structures of an amphiphilic conjugated graft copolymer, poly(2,3-diphenyl-5-(trimethylene-heptadeca(oxyethylene)-methoxy-phenylene vinylene) (denoted as PVEO(17)) composing of a conjugated DP-PPV backbone and PEO side chains, in bulk and solutions with tetrahydrofuran (THF) and water have been investigated by small-angle X-ray scattering (SAXS). In bulk state, the DP-PPV main chains in PVEO(17) stacked to form flat disk microdomains dispersed in the PEO side-chain matrix. The corresponding wide angle X-ray scattering pattern revealed the existence of crystallinity of the PEO side chains. The structure of the polymer in solution was affected by the solvent quality and the polymer concentration. PVEO(17) chains were relatively well dispersed in THF. In aqueous solutions, however, the amphiphilic PVEO(17) chains aggregated significantly over the concentration range of 1-8 wt%, where the polymer was found to self-organize to form cylindrical micelles with the aggregation number increasing with the increase of concentration. The photophysical properties characterized by UV-Vis and photoluminescence spectroscopy were strongly affected by the aggregation state of the polymer. (C) 2009 Elsevier Ltd. All rights reserved.
Thermally-induced order-order transition of DNA-cationic surfactant complexes
(2006-08-29)
Hsu, Wei-Long
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Li, Yen-Cheng
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Chen, Hsin-Lung
;
Liou, Willisa
;
Jeng, U-Ser
Polyanionic DNA interacts with cationic amphiphiles to form electrostatic complexes exhibiting rich self-assembled structures. This type of complex has been considered as a nonviral carrier in gene therapy and as a template for nanostructure construction. Here we report a thermally-induced phase transition of the complexes of DNA with the mixtures of a cationic surfactant, dodecyltrimethyl bromide (DTAB), and a neutral lipid, dioleoylphosphatidylethanolamine (DOPE), in fully hydrated state. An order-order transition between a multilamellar (L-alpha(c)) phase and an inverted hexagonal (H-II(c)) phase was found to occur with the transition temperature adjustable by the DTAB-to-DNA base pair molar ratio (x) and DOPE-to-DTAB molar ratio (m). The stability of the L-alpha(c) phase was enhanced at lower m and x, as the L-alpha(c)-to-H-II(c) transition temperature increased with the decreases of these two parameters. The suppression of L-alpha(c)-to-H-II(c) transition at lower x was attributed to the lower entropic gain from the counterion release due to the presence of uncomplexed DNA in the bulk solution.
Two-dimensional densely packed DNA nanostructure derived from DNA complexation with a low-generation poly(amidoamine) dendrimer
(2007-01-30)
Su, Chun-Jen
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Liu, Yi-Chun
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Chen, Hsin-Lung
;
Li, Yen-Cheng
;
Lin, Hsien-Kuang
One of the keys for using deoxyribonucleic acid (DNA) as a nanomaterial relies on how the individual DNA chain can be aligned and how a multitude of DNA chains can be packed into ordered nanostructures. Here we present a simple method for constructing a 2-D densely packed DNA nanostructure using the electrostatic complex of DNA with a poly(amidoamine) (PAMAM) dendrimer of generation two. Ordered DNA arrays are formed by drop-casting an aqueous solution containing positively overcharged complexes onto mica followed by a prolonged incubation. During the incubation, the complexes tend to adsorb onto the negatively charged mica surface through electrostatic attraction. The rodlike complexes organize to form ordered arrays to increase the surface density of the adsorbed complexes and hence the attractive free energy of adsorption. The densely packed nanostructure obtained here is distinguished from the previously reported spheroid or toroid structure derived from DNA complexations with the higher-generation dendrimers.