Browsing by Author "Lee, GH"

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Calix[4]arenes with a lid in their upper rims: 1,3-dipolar cycloaddition reactions of benzonitrile oxides with 5-allyl-, 5,11-dially- and 5,17-diallylcalix[4]arenes
(2000-02-01)
Shu, CM
;
Lin, WL
;
Lee, GH
;
Peng, SM
;
Chung, WS
The upper rim substituted mono- and diisoxazolinomethylcalix[4]arenes 9-23 are synthesized in good yields from 1,3-dipolar cycloaddition reactions of para-substituted phenyl nitrileoxides with 5-allyl-, 5,11-diallyl- and 5,17-diallycalix[4]arenes 5-7; the structures of 9-23 are consistent with a 'cone' conformation and the 'vase-with-a-lid' structure of 11 was confirmed by a single-crystal x-ray analysis. Preliminary results show that the monoisoxazolinomethylcalix[4]arene can form an inclusion complex with ammonium cation.
Direct observation of the lateral nonuniform channel doping profile in submicron MOSFET's from an anomalous charge pumping measurement results
(1995)
Chung, SS
;
Cheng, SM
;
Lee, GH
;
Guo, JC
;
電子工程學系及電子研究所
Formation of mononuclear nitrido complexes of chromium(VI) and molybdenum(VI); Syntheses and X-ray crystal structures of N Cr(OBu(t))(3) and N Mo(OSiMe(3))(3)(py)
(1996-01-21)
Chiu, HT
;
Chen, YP
;
Chuang, SH
;
Jen, JS
;
Lee, GH
Mononuclear nitrido complexes of Cr and Mo, N=Cr(OBu(t))(3) and N=Mo(OSiMe(3))(3)(py), are synthesized; the chromium complex has an idealized C-3v symmetry while the molybdenum complex has a distorted square-pyramidal geometry with the nitrido ligand at apical position; the N-Cr distance is 1.538(5) Angstrom while the average N-Mo distance is 1.627 Angstrom.
Heteroleptic cyclometalated iridium(III) complexes displaying blue phosphorescence in solution and solid state at room temperature
(2005-10-31)
Yang, CH
;
Li, SW
;
Chi, Y
;
Cheng, YM
;
Yeh, YS
A series of heteroleptic Ir(III) metal complexes 1-3 bearing two N-phenyl-substituted pyrazoles and one 2-pyridyl pyrazole (or triazole) ligands were synthesized and characterized to attain highly efficient, room-temperature blue phosphorescence. The N-phenylpyrazole ligands, dfpzH = 1-(2,4-difluorophenyl)pyrazole, fpzH = 1-(4-fluorophenyl)-pyrazole, dfmpzH = 1-(2,4-difluorophenyl)-3,5-dimethylpyrazole, and fmpzH = 1-(4-fluorophenyl)-3,5-dimethylpyrazole, show a similar reaction pattern with respect to the typical cyclometalated (C boolean AND N) chelate, which utilizes its orthosubstituted phenyl segment to link with the central Ir(III) atom, while the second 2-pyridylpyrazole (or triazole) ligand, namely, fppzH = 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, fptzH = 3-(trifluoromethyl)-5-(2-pyridyl)triazole, and hptzH = 3-(heptafluoropropyl)-5-(2-pyridyl)triazole, undergoes typical anionic (N boolean AND N) chelation to complete the octahedral framework. X-ray structural analyses on complexes [(dfPZ)(2)Ir(fppz)] (1a) and [(fMPZ)(2)Ir(hptz)] (3d) were established to confirm their molecular structures. Increases of the pi pi* energy gaps of the Ir(III) metal complexes were systematically achieved with two tuning strategies. One involves the substitution for one or two fluorine atoms at the N-phenyl segment or the introduction of two electron-releasing methyl substituents at the pyrazole segment of the H(CAN) ligands. Alternatively, we have applied the more electron-accepting triazolate in place of the pyrazolate segment for the third (N boolean AND N)H ligand, Our results, on the basis of steady-state, relaxation dynamics, and theoretical approaches, lead to a conclusion that, for complexes 1-3, the weakening of iridium metal-ligand bonding strength in the T-1 state plays a crucial role for the fast radiationless deactivation. For the case of [(fMPZ)(2)Ir(hptz)] (3d), a thermal deactivation barrier of 4.8 kcal/mol was further deduced via temperature-dependent studies. The results provide a theoretical basis for future design and synthesis of the corresponding analogues suited to blue phosphorescent emitters.
Highly efficient red phosphorescent osmium(II) complexes for OLED applications
(2004-07-19)
Tung, YL
;
Wu, PC
;
Liu, CS
;
Chi, Y
;
Yu, JK
The nonionic, red-emitting complexes [Os(fppz)(2)L-2] (L = PPh2Me (1), PPhMe2 (2)) and [Os(bptz)(2)L-2] (L = PPh2Me (3)) were synthesized, showing highly intense red phosphorescent emission in CH2Cl2 solution at lambda(max) 617, 632, and 649 nm, respectively. The electroluminescent properties of these compounds on OLEDs showed promising device efficiencies required for future OLED applications.
Interplay between intra- and interligand charge transfer with variation of the axial N-heterocyclic ligand in osmium(II) pyridylpyrazolate complexes: Extensive color tuning by phosphorescent solvatochromism
(2005-10-21)
Li, SW
;
Cheng, YM
;
Yeh, YS
;
Hsu, CC
;
Chou, PT
The rational design and syntheses of a new series of Os-II complexes with formula [Os(fppz)(2)(CO)(L)] (1: L=4-dimethylaminopyridine; 2: L=pyridine; 3: L = 4,4'bipyridine; 4: L=pyridazine; 5: L = 4-cyanopyridine), bearing two (2-pyridyl)pyrazolate ligands (fppz) together with one carbonyl and one N-heterocyclic ligand at the axial positions are reported. Single-crystal X-ray diffraction studies of, for example, 2 reveal a distorted octahedral geometry in which both fppz ligands reside in the equatorial plane with a trans configuration and adopt a bent arrangement at the metal center with a dihedral angle of similar to 23 degrees, while the carbonyl and pyridine ligands are located at the axial positions. Variation of the axial N-heterocyclic ligand leads to remarkable changes in the photophysical properties as the energy gap and hence the phosphorescence peak wavelength can be tuned. For complexes 1 and 2 the solvent-polarity-independent phosphorescence originates from a combination of intraligand (3)pi-pi* ((ILCT)-I-3) and metal-to-ligand charge transfer transitions ((MLCT)-M-3). In sharp contrast, as supported by cyclic voltammetry measurements and theoretical calculations, complexes 3-5 exhibit mainly ligand-to-lilgand charge transfer (LLCT) transitions, resulting in a large dipolar change. The phosphorescence of complexes 3-5 thus exhibits a strong dependence on the polarity of the solvent, being shifted for example, from 560 (in C6H12) to 665 nm (in CH3CN) and from 603 (in C6H12) to 710 nm (in CH3CN) for complexes 3 and 5, respectively. The results clearly demonstrate that a simple, straightforward derivatization of the axial N-heterocyclic ligand drastically alters the excitation properties per se from intraligand charge transfer (ILCT) to LLCT transitions. The latter exhibit remarkable LLCT phosphorescence solvatochromism so that a broad range of color tunability can be achieved.
Iridium(III) complexes with orthometalated quinoxaline ligands: Subtle tuning of emission to the saturated red color
(2005-03-07)
Hwang, FM
;
Chen, HY
;
Chen, PS
;
Liu, CS
;
Chi, Y
Rational design and syntheses of four iridium complexes (1-4) bearing two substituted quinoxalines and an additional 5-(2-pyridyl) pyrazolate or triazolate as the third coordinating ligand are reported. Single-crystal X-ray diffraction studies of 1 reveal a distorted octahedral geometry, in which two dpqx ligands adopt an eclipse configuration, for which the quinoxaline N atoms and the C atoms of orthometalated phenyl groups are located at the mutual trans-and cis-positions, respectively. The lowest absorption band for all complexes consists of a mixture of heavy-atom Ir(III)-enhanced (MLCT)-M-3 and (3)pipi(*) transitions, and the phosphorescent peak wavelength can be fine-tuned to cover the spectral range of 622-649 nm with high quantum efficiencies. The cyclic voltarnmetry was measured, showing a reversible, metal-centered oxidation with potentials at 0.76-1.03 V, as well as two reversible reduction waves with potentials ranging from -1.61 to -2.06 V, attributed to the sequential addition of two electrons to the more electron-accepting heterocyclic portion of two distinctive cyclometalated CAN ligands. Complex 1 was used as the representative example to fabricate the red-emitting PLEDs by blending it into a PVK-PBD polymer mixture. The devices exhibited the characteristic emission profile of 1 with peak maxima located at 640 nm. The maximum external quantum efficiency was 3.15% ph/el with a brightness of 1751 cd/M-2 at a current density of 67.4 mA/cm(2) and the maximum brightness of 7750 cd/m(2) was achieved at the applied voltage of 21 V and with CIE coordinates of (0.64, 0.31).
Low-temperature solution route to molybdenum nitride
(1998-12-01)
Chiu, HT
;
Chuang, SH
;
Lee, GH
;
Peng, SM
;
應用化學系
Low-temperature solution route to molybdenum nitride
(1998-12-01)
Chiu, HT
;
Chuang, SH
;
Lee, GH
;
Peng, SM
;
應用化學系
Metallo-organic chemical vapor deposition of tantalum carbide and tantalum nitride thin films from (BuCH)-Bu-t=Ta(CH2 Bu-t)(3) and (BuN)-Bu-t=Ta(CH2 Bu-t)(3).
(2002-04-07)
Chiu, HT
;
Chang, YH
;
Chang, PJ
;
Wu, JB
;
Peng, SM
Nonlinear optical chromophores with configuration-locked polyenes possessing enhanced thermal stability and chemical stability
(1998-11-01)
Shu, CF
;
Shu, YC
;
Gong, ZH
;
Peng, SM
;
Lee, GH
A synthetic strategy has been developed for preparation of NLO chromophores with all the pi-conjugated methine groups incorporated into plane-rigidified, fused, six-membered rings. The comparison of the rigidified chromophores to the analogous nonrigid chromophores shows that the configuration-locking methods provide a dramatic enhancement of molecular thermal stability. The data from W-vis spectroscopy and X-ray crystallography reveal that the rigidity of the annulated rings does not diminish the planarity and the electron delocalization efficiency of the polyenic chain.
Nonlinear optical chromophores with configuration-locked polyenes possessing enhanced thermal stability and chemical stability
(1998-11-01)
Shu, CF
;
Shu, YC
;
Gong, ZH
;
Peng, SM
;
Lee, GH
A synthetic strategy has been developed for preparation of NLO chromophores with all the pi-conjugated methine groups incorporated into plane-rigidified, fused, six-membered rings. The comparison of the rigidified chromophores to the analogous nonrigid chromophores shows that the configuration-locking methods provide a dramatic enhancement of molecular thermal stability. The data from W-vis spectroscopy and X-ray crystallography reveal that the rigidity of the annulated rings does not diminish the planarity and the electron delocalization efficiency of the polyenic chain.
Polyfluorene containing diphenylquinoline pendants and their applications in organic light emitting diodes
(2005-02-15)
Su, HJ
;
Wu, FI
;
Shu, CF
;
Tung, YL
;
Yun, C
We present a short, efficient synthetic route for the preparation of a novel polyfluorene copolymer (PF-Q) containing two electron-deficient, 2,4-diphenylquinoline groups functionalized at the C-9 positions of alternate fluorene units that form a three-dimensional cardostructure. The presence of the rigid bulky pendent groups leads to a polyfluorene possessing a high glass-transition temperature (207 degreesC) and very good thermal stability (5% weight loss observed at 460 degreesC). A photoluminescence study revealed that the Forster energy transfer from the excited quinoline groups to the polyfluorene backbone is Very efficient; it also demonstrated that, the commonly observed aggregate/excimer formation in polyfluorenes is suppressed very effectively, in this polymer, even after it has been annealed at 150 degreesC for 20 h. A light emitting diode (LED) device prepared with PF-Q as the emitting layer exhibits a stable blue emission with a maximum brightness of 1121 cd/m(2) at 12 V and a maximum external quantum efficiency of 0.80% at 250 cd/m(2). We also used PF-Q, which contains diphenylquinoline units that behave as electron-transporting side chains, as a host. material and doped it with 2.4 wt % of a red-emitting phosphorescent dye, Os(fppz). to realize a red electrolumineseence with CIE color coordinates of (0.66, 0.34). The doped device exhibits a maximum external quantum efficiency of 6.63% (corresponding a luminance efficiency of 8.71 cd/A) at a current density of 47.8 mV/cm(2) together with a maximum brightness of 10457 cd/m(2). (C) 2005 Wiley Periodicals, Inc.
Stable organic blue-light-emitting devices prepared from poly[spiro(fluorene-9,9'-xanthene)]
(2005-11-29)
Tseng, YH
;
Shih, PI
;
Chien, CH
;
Dixit, AK
;
Shu, CF
A short, efficient synthetic route has been developed for the preparation of 2,7-dibromospiro-[fluorene-9,9'-(2',7'-di-n-octyloxyxanthene)], which was subsequently polymerized with the corresponding diborolane through Suzuki coupling to afford a fluorene-based homopolymer, PSFX, that contains a spiroxanthene group functionalized on the C-9 position of each fluorene repeat unit. Single-crystal X-ray diffraction analysis of the dibromo monomer revealed that the spiro-fused fluorene and xanthene moieties lie perpendicular to one another. As a consequence of the incorporation of the spiro pendant group, PSFX possesses a high glass transition temperature and good thermal stability while displaying its stable blue emission in the solid state. A light-emitting diode device prepared using PSFX as the emitting layer exhibits an efficient, stable blue emission; it has a turn-on voltage of 6 V and a maximum external quantum efficiency of 1.74% ph/el. Even when the brightness was increased up to 10(3) cd/m(2) (ca. 11 V), the CIE color coordinates of the resulting EL spectrum remained in the deep-blue region (0.15, 0.07) and the device's efficiency was 1.33% ph/el.
Syntheses and characterization of organoimido complexes of niobium(V); Potential CVD precursors
(1998-06-01)
Chiu, HT
;
Lin, JC
;
Chuang, SH
;
Lee, GH
;
Peng, SM
New niobium imido complexes (RN)Nb(NEt2)(3) (R = Pr-n, Pr-i and Bu-t), potential precursors to grow niobium containing thin films by chemical vapor deposition (CVD), were prepared by reacting the corresponding (RN)NbCl(3)py(2) complexes (R = Pr-n, Pr-i and Bu-t; py = pyridine) with LiNEt2 in hydrocarbon solvents. The structures of (RN)NbCl(3)py(2) (R = Pr-i and Bu-t), determined by X-ray crystallography, are mononuclear with distorted octahedral geometries. For each complex, three chloride ligands are cia to the imido ligand and occupy meridional positions. One of two py ligands is cia to and the other is trans to the imido ligand. For ((PrN)-N-i)NbCl(3)py(2), the Nb = NPri bond distance (Angstrom) is 1.733(3) and the angle Nb=N-Pr-i angle (degrees) is 178.0(3). Crystal data: monoclinic, space group P2(1)/n, a = 8.805(2), b = 14.930(4), c = 13.407(3) Angstrom, beta = 93.37(2)degrees, V = 1759.5(7) Angstrom(3), Z = 4, D-c 1.565 g cm(-3). For ((BuN)-N-t)NbCl(3)py(2), the Nb=NBut bond distance (Angstrom) is 1.734(4) and the angle Nb=N-Bu-t angle (degrees) is 174.8(4). Crystal data: monoclinic, space group P2(1)/c, a = 9.609(1), b = 13.591(6), c = 14.615(2) Angstrom, beta = 90.05(1)degrees, V = 1908.5(9) Angstrom(3), Z = 4, D-c = 1.492 g cm(-3).
Syntheses and characterization of organoimido complexes of tantalum; potential single-source precursors to tantalum nitride
(1998)
Chiu, HT
;
Chuang, SH
;
Tsai, CE
;
Lee, GH
;
Peng, SM
New single-source precursor to tantalum nitride thin films, ((BuN)-N-t)Ta(NEt2)(3), and related complexes, (RN)Ta(NEt2)(3) (R = Pr-i and Pr-n), were prepared by reacting corresponding (RN)TaCl(3)py(2) complexes (R = Bu-t, Pr-i and Pr-n) with LiNEt2 in hydrocarbon solvents. The structure of ((BuN)-N-t)TaCl(3)py(2) was determined by X-ray crystallography. (C) 1998 Elsevier-Science Ltd. All rights reserved.
Syntheses of molybdenum nitrido complexes from (NH4)(2)Mo2O7.
(2002-04-07)
Yeng, MY
;
Chiu, HT
;
Chuang, SH
;
Lo, CP
;
Peng, SM
Synthesis and characterization of nonlinear optical chromophores with conformationally locked polyenes possessing enhanced thermal stability
(1999-06-01)
Shu, YC
;
Gong, ZH
;
Shu, CF
;
Breitung, EM
;
McMahon, RJ
Dipolar NLO chromophores with an interposed conjugated tetraene segment in which all but four of the methine groups are incorporated into a tetrahydronaphthalene framework have been synthesized and characterized. This conformation-locking approach furnishes NLO chromophores possessing an enhanced thermal stability. X-ray crystallographic data indicate that the polyenic chain of these molecules exhibits a near-planar all-trans conformation in the solid state. EFISH measurements show that these conformationally locked tetraenic chromophores exhibit large second-order optical nonlinearities (mu.beta similar to 4000 x 10(-48) cm(6) at 1907 nm), although the nonlinearities of the corresponding "unlocked" analogues are slightly larger.
Synthesis and characterization of soluble poly(ether imide)s based on 2,2 '-bis(4-aminophenoxy)-9,9 '-spirobifluorene
(2003-02-01)
Reddy, DS
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Chou, CH
;
Shu, CF
;
Lee, GH
;
應用化學系
A series of aromatic poly(ether imide)s containing 9,9'-spirobifluorene moieties in the main chain have been synthesized via the polycondensation of 2,2'-bis(4-aminophenoxy)-9,9'-spirobifluorene with a variety of aromatic dianhydrides. In the diamine monomer, the two aminophenoxyfluorene entities are orthogonally arranged and are connected through an sp(3) carbon atom (the spiro center). The resulting poly(ether imide)s have a polymer backbone which is periodically twisted with an angle of 90degrees at each spiro center. This structural feature, which restricts the close packing of the polymer chains and reduces inter-chain interactions, leads to amorphous poly(ether imide)s with good solubility in common organic solvents. In addition, the rigidity of the main chain of these polymers appears to be preserved due to the spiro-structure. As a result, these poly(ether imide)s exhibit a high T-g and excellent thermal stability. (C) 2002 Elsevier Science Ltd. All rights reserved.
Tuning the emission and morphology of cyclometalated iridium complexes and their applications to organic light-emitting diodes
(2005)
Wu, FI
;
Su, HJ
;
Shu, CF
;
Luo, LY
;
Diau, WG
We have synthesized two highly efficient phosphorescent iridium metal complexes, Ir( DPQ)(2)( acac) and Ir(FPQ)(2)(acac), which are based on cyclometalated quinoline ligands, and discuss details of their electrochemical behavior and photophysical properties (viz. absorption and photoluminescence). Single-crystal X-ray diffraction studies of Ir(DPQ)(2)(acac) reveal a distorted octahedral geometry, in which the quinoline N atoms and the C atoms of the orthometalated phenyl groups are located at mutual trans and cis positions, respectively. In contrast, Ir(FPQ)(2)( acac) is an amorphous solid and undergoes a glass transition at 92 degreesC, which we attribute to the presence of the long di-n-octyl chains in the fluorenyl groups. The phosphorescence of these Ir complexes originates from the dominant 3 MLCT excited state shifts to red that occur upon introducing a phenyl substituent and/or a large conjugating aromatic ring into the ligand. A polymer light-emitting diode (PLED) device that uses Ir(FPQ)(2)(acac) as a phosphorescent dopant and a PVK/PBD blend as the host material produces very high efficiency (an external quantum efficiency of 8.16% at 100 mA cm(-2)) and a pure-red emission with 1931 CIE ( Commission Internationale de L'Eclairage) chromaticity coordinates of (x = 0.68, y = 0.32).