Browsing by Author "Ho, Ming-Shou"

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Screening Libraries of Semifluorinated Arylene Bisimides to Discover and Predict Thermodynamically Controlled Helical Crystallization
(2016-12)
Ho, Ming-Shou
;
Partridge, Benjamin E.
;
Sun, Hao-Jan
;
Sahoo, Dipankar
;
Leowanawat, Pawaret
Synthesis, structural, and retrostructural analysis of a library containing 16 self-assembling perylene (PBI), 1,6,7,12-tetrachloroperylene (Cl4PBI), naphthalene (NBI), and pyromellitic (PMBI) bisimides functionalized with environmentally friendly AB(3) chiral racemic semifluorinated minidendrons at their imide groups via m = 0, 1, 2, and 3 methylene units is reported. These semifluorinated compounds melt at lower temperatures than homologous hydrogenated compounds, permitting screening of all their thermotropic phases via structural analysis to discover thermodynamically controlled helical crystallization from propeller-like, cogwheel, and tilted molecules as well as lamellar-like structures. Thermodynamically controlled helical crystallization was discovered for propeller-like PBI, Cl4PBI and NBI with m = 0. Unexpectedly, assemblies of twisted Cl(4)PBIs exhibit higher order than those of planar PBIs. PBI with m = 1, 2, and 3 form a thermodynamically controlled columnar hexagonal 2D lattice of tilted helical columns with intracolumnar order. PBI and Cl4PBI with m = 1 crystallize via a recently discovered helical cogwheel mechanism, while NBI and PMBI with m = 1 form tilted helical columns. PBI, NBI and PMBI with m = 2 generate lamellar-like structures. 3D and 2D assemblies of PBI with m = 1, 2, and 3, NBI with m = 1 and PMBI with m = 2 exhibit 3.4 angstrom pi-pi stacking. The library approach applied here and in previous work enabled the discovery of six assemblies which self-organize via thermodynamic control into 3D and 2D periodic arrays, and provides molecular principles to predict the supramolecular structure of electronically active components.
Synthesis and Hierarchical Superstructures of Side-Chain Liquid Crystal Polyacetylenes Containing Galactopyranoside End-Groups
(2009-12-01)
Ho, Ming-Shou
;
Hsu, Chain-Shu
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應用化學系
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Department of Applied Chemistry
Three kinds of chiral saccharide-containing liquid crystalline (LC) acetylenic monomers were prepared by click reaction between 2-azidoethyl-2,3,4,6-tetraacetyl-beta-D-galactopyranoside and 1-biphenylacetylene 4-alkynyloxybenzoate. The obtained monomers were polymerized by WCl(6)-Ph(4)Sn to form three side-chain LC polyacetylenes containing 1-[2-(2,3,4,6-tetraacetyl-beta-D-galactopyranos-1-yl)-ethyl]-1H-[1,2,3]-triazol-4'-biphenyl 4-alkynyloxybenzoate side groups. All monomers and polymers show a chiral smectic A phase. Self-assembled hiearchical superstructures of the chiral saccharide-containing LCs and LCPs in solution state were studied by field-emission scanning electron microscopy. Because of the LC behavior, the LC molecules exhibit a high segregation strength for phase separation in dilute solution (THF/H(2)O = 1:9 v/v). The self-assembled morphology of LC monomers was dependent upon the alkynyloxy chain length. Increasing the alkynyloxy chain length caused the self-assembled morphology to change from a platelet-like texture (LC-6) to helical twists morphology (LC-11 and LC-12). Furthermore, the helical twist morphological structure can be aligned on the polyimide rubbed glass substrate to form two-dimensional ordered helical patterns. In contrast to LC monomers, the LCP-11 self-assembled into much more complicate morphologies, including nanospheres and helical nanofibers. These nanofibers are evolved from the helical cables ornamented with entwining nanofibers upon natural evaporation of the solution in a mixture with a THF/methanol ratio of 3:7. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47:6596-6611, 2009
Synthesis and self-assembled nanostructures of novel chiral amphiphilic liquid crystals containing -beta-galactopyranoside end-groups
(2010)
Ho, Ming-Shou
;
Hsu, Chain-Shu
;
應用化學系
;
Department of Applied Chemistry
A series of novel chiral amphiphilic liquid crystals that contain -d-galactopyranoside end-group and 4-[1,2,3]-triazolephenyl 4-alkoxybenzoate mesogens were synthesised. Their phase transitions and mesomorphic properties were characterised by polarising optical microscopy and differential scanning calorimetry. All compounds obtained exhibit a chiral smectic A phase. In addition, the self-assembling behaviour in the solution of these liquid crystal amphiphiles that exhibited high segregation strength for phase separation was studied by electron microscopy. The morphological transformation of self-assembled chiral amphiphilic liquid crystals, from a platelet-like morphology to helical twists, was obtained by increasing the length of the hydrophobic alkyl tail.
Synthesis of Thermal-Stable and Photo-Crosslinkable Polyfluorenes for the Applications of Polymer Light-Emitting Diodes
(2010-02-01)
Wang, Pei-Hsuan
;
Ho, Ming-Shou
;
Yang, Sheng-Hsiung
;
Chen, Kuei-Bai
;
Hsu, Chain-Shu
Three polyfluorene derivatives which have oxetane-containing phenyl group at C-9 position were synthesized via the palladium-catalyzed Suzuki-coupling reaction. The synthesized polymers PFB, PFG, and PFR emit blue, green, and red light, respectively. A double-layer device with the configuration of ITO/PEDOT/polymer/Ca/Al using PFB as the active layer showed a threshold voltage of 5 V, a maximum brightness of 2030 cd/m(2), and a maximum current efficiency of 0.35 cd/A. Using PFG as the active layer, the device exhibited a threshold voltage of 6 V, a maximum brightness of 6447 cd/m(2), and a maximum current efficiency of 1.27 cd/A. Using PFR as the active layer, the device showed a threshold voltage of 4 V, a maximum brightness of 2135 cd/m(2), and a maximum current efficiency of 0.16 cd/A. Better electroluminescent performance was also found based on different design of device structures. Due to photo-crosslinking property of oxetane groups, the UV-exposed thin films are insoluble in common organic solvents. A device comprised of blue, green, and red-emissive pixels was successfully fabricated by spin-coating and photo-lithographic processes. In addition, a white light-emitting device with CIE coordinate of (0.34, 0.33) was achieved by blending PFR into a host material PFB as the active layer. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 516-524, 2010
Twist Ferrocene Wires from Self-Assembly of Chiral Rod-Coil Organometallics
(2010)
Lin, Tz-Feng
;
Ho, Rong-Ming
;
Sung, Chien-Hung
;
Ho, Ming-Shou
;
Hsu, Chain-Shu