Showing papers by "Wai Yeung Wong published in 2005"
TL;DR: In this article, a trifunctional Pt(II) cyclometalated complex was synthesized, in which the hole-transporting (HT), electron-transport (ET), and electroluminescent (EL) components were integrated into a single molecule.
196 citations
TL;DR: In this paper, a review of metal-based functional materials of fluorenes and their derivatives is presented, focusing on the properties of these metal-organic compounds and their applications in the field of optoelectronics and molecular electronics.
174 citations
TL;DR: In this paper, a review of research work carried out by the author in the past decade on rigid-rod transition metal polyyne polymers and their molecular precursors is presented.
Abstract: This review briefly summarizes research work carried out by the author in the past decade on rigid-rod transition metal polyyne polymers and their molecular precursors. The research involves the synthesis, spectroscopic and photophysical characterization, ligand functionalization, and possible optoelectronic applications of transition metal polyyne polymers. Herein, oligomeric and polymeric metal alkynyl systems of the late transition metals are discussed, and particular attention is focused on the electronic absorption spectroscopy and photoluminescence behavior, thermal stability and structural aspects of these polymetallaynes. A detailed account of the evolution of the first excited singlet and triplet state on the electronic structure of the organic spacer groups of these metal polyyne polymers is also given and the interplaying factors that govern the spatial extent of the lowest-lying singlet and triplet energy levels for the chemical tailoring of the singlet–triplet gap are elucidated. The possible developments of this research are also envisaged.
121 citations
TL;DR: In this article, the optical transmittance characteristics of a series of solution-processable platinum polyyne polymers at 532 nm were investigated, and it was shown that they are excellent optical limiters with performance comparable or superior to those of the state-of-the-art reverse saturable absorption dyes such as fullerene C60 and metal phthalocyanine complexes.
Abstract: Experimental investigations of the nonlinear optical transmittance characteristics of a series of solution-processable platinum polyyne polymers at 532 nm show that they are excellent optical limiters with performance comparable or superior to those of the state-of-the-art reverse saturable absorption dyes such as fullerene C60 and metal phthalocyanine complexes. On the basis of results from photophysical studies, both the inclusion of a platinum chromophore for increasing the intersystem crossing rate and the formation of an intramolecular charge-transfer state between the electron-withdrawing and electron-donating moieties along the polymer chain are very effective approaches for the enhancement of the optical-limiting properties of these metal polyynes. The structural influence of the aryl linker units on the optical-limiting action has been evaluated in detail. The optical-limiting thresholds for these polymetallaynes range from 0.06 to 0.15 J/cm2 at 82% linear transmittance, and these polymeric mater...
92 citations
TL;DR: In this paper, Suzuki-type coupling polymerization of fluorene−diboronic ester with some 9-aryl-3,6-dibromocarbazole derivatives was used to obtain copolymers with high glass transition temperatures.
Abstract: Several soluble and well-defined copolymers of 9,9-dihexyl-2,7-fluorene and 9-aryl-3,6-carbazole (aryl = phenyl, p-methylphenyl, p-methoxyphenyl) were prepared in good yields by Suzuki-type coupling polymerization of fluorene−diboronic ester with some 9-aryl-3,6-dibromocarbazole derivatives. These copolymers showed high glass transition temperatures, and their regiochemical structures and physical properties were studied by gel permeation chromatography, NMR, UV absorption, elemental analysis, thermogravimetry, photoluminescence, and quantum yield measurements. The influence of the carbazole core and its aryl substituent on the photophysical, electrochemical, and electroluminescent properties of these alternating fluorene/carbazole copolymers has been investigated. Both the absorption and photoluminescence peaks of these copolymers are blue-shifted relative to the poly(9,9-dihexylfluorene) homopolymer (PF-C6), and cyclic voltammetry showed that these copolymers have their HOMO energy levels raised relativ...
76 citations
TL;DR: In this paper, a series of thermally stable group 10 platinum(II) and group 12 mercury (II) poly-yne polymers containing biphenyl spacer trans -[Pt(PBu 3 ) 2 C C( p -C 6 H 4 ) 2C C C−] n and [HgC C(p -C6 H 4 2 C −] n were prepared in good yields by Hagihara's dehydrohalogenation reaction of the corresponding metal chloride precursors with 4,4′-diethynylbip
60 citations
TL;DR: Competition experiments revealed that compound 4 (or 5) has a highly selective response to mercury(II) ion in aqueous solution.
Abstract: Novel 2,3-bis(1H-pyrrol-2-yl)quinoxaline-functionalized Schiff bases were prepared and characterized as new fluorescent sensors for mercury(II) ion. The X-ray crystal structures of compounds 4, 5, 4a and 5a were determined. The binding properties of 4 and 5 for cations were examined by UV-vis and fluorescence spectroscopy. The UV-vis and fluorescence data indicate that a 1 : 1 stoichiometric complex is formed between compound 4
(or 5) and mercury(II) ion, and the association constant is (3.81 ± 0.7)
× 105 M−1 for 4 and (3.43 ± 0.53)
× 105 M−1 for 5. The recognition mechanism between compound 4
(or 5) and metal ion was discussed based on their chemical construction and the fluorescence quenching effect when they interact with each other. Competition experiments revealed that compound 4
(or 5) has a highly selective response to mercury(II) ion in aqueous solution.
60 citations
TL;DR: A series of conjugated bimetallic complexes and their polymeric analogues containing alkyne-functionalized α-coupled oligothiophenes have been synthesized and characterized as mentioned in this paper.
Abstract: A series of conjugated bimetallic complexes and their polymeric analogues containing alkyne-functionalized α-coupled oligothiophenes have been synthesized and characterized. The introduction of transition metal centers, with their large variety of ligand environments and oxidation states, can impart interesting physical, optoelectronic and structural properties on these oligothiophene systems. It was demonstrated that π-conjugation of organometallic alkynyl units into the oligothiophene chain offers intriguing models that possess unique features that are not accessible in the classical organic counterparts. The photophysical, electrochemical and structural properties of these classes of metallaynes have been extensively investigated in terms of the type of metal centers and the number of oligothienyl rings within the bridging ligand. The experimental results have also been correlated to the theoretical data obtained by molecular orbital calculations using density functional theory.
48 citations
TL;DR: In this article, the synthesis and structural characterisation of some new tetranuclear cadmium(II) Schiff-base complexes were described, and all of the complexes were fully characterised by spectroscopic (FTIR, NMR and FAB MS) methods and their molecular structures were confirmed by single crystal X-ray analysis.
Abstract: The synthesis and structural characterisation of some new tetranuclear cadmium(II) Schiff-base complexes were described. Reaction of the hexadentate Schiff-base ligands (H2L) with an excess of cadmium(II) acetate, Cd(OAc)2, furnished novel tetracadmium complexes of the general formula [Cd4(L)2(OAc)4], which exhibit an interesting three-dimensional cage-like structure of four ligand-supported cadmium atoms. All of the complexes were fully characterised by spectroscopic (FTIR, NMR and FAB MS) methods and their molecular structures were confirmed by single-crystal X-ray analysis. The X-ray crystal structures of these tetranuclear Schiff-base complexes represent the first structurally characterised examples of this kind for the cadmium triad. These new complexes were found to display rich photophysical properties and they all exhibited low-temperature phosphorescence in the frozen state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
42 citations
TL;DR: The reaction of Ln[N(SiMe3)2]3.[LiCl(THF)3](x)(Ln = Yb and Er) with N-confused tetraphenylporphyrin gives (NCTPP)Ln(L(OMe), whose X-ray structures exhibit an eta2 agostic interaction between the metal centre and the inner C-H bond of the NCTPP ligand.
29 citations
TL;DR: In this article, a series of ferrocenyl end-capped bis(butadiynyl) fluorene complexes have been synthesized in moderate yields by the oxidative coupling reactions of ethynylferrocene with half equivalents of the appropriate diethynyllfluorene derivatives.
TL;DR: Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) and the same reaction yielded the di-mu-sulfato complex, which is paramagnetic with a measured magnetic moment of about 2.4 mu.
Abstract: Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) (L(OEt) (-)=[(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(2)(mu-SO(4))] (2). In more concentrated sulfuric acid (>1 M), the same reaction yielded the di-mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(mu-SO(4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF(3)SO(3)) gave the tris(triflato) complex [L(OEt)Ti(OTf)(3)] (4), whereas treatment of 2 with Ag(OTf) in CH(2)Cl(2) afforded the sulfato-capped trinuclear complex [{(L(OEt))(3)Ti(3)(mu-O)(3)}(mu(3)-SO(4)){Ag(OTf)}][OTf] (5), in which the Ag(OTf) moiety binds to a mu-oxo group in the Ti(3)(mu-O)(3) core. Reaction of 2 in H(2)O with Ba(NO(3))(2) afforded the tetranuclear complex (L(OEt))(4)Ti(4)(mu-O)(6) (6). Treatment of 2 with [{Rh(cod)Cl}(2)] (cod=1,5-cyclooctadiene), [Re(CO)(5)Cl], and [Ru(tBu(2)bpy)(PPh(3))(2)Cl(2)] (tBu(2)bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag(OTf) afforded the heterometallic complexes [(L(OEt))(2)Ti(2)(O)(2)(SO(4)){Rh(cod)}(2)][OTf](2) (7), [(L(OEt))(2)Ti(O)(2)(SO(4)){Re(CO)(3)}][OTf] (8), and [{(L(OEt))(2)Ti(2)(mu-O)}(mu(3)-SO(4))(mu-O)(2){Ru(PPh(3))(tBu(2)bpy)}][OTf](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu(B). Treatment of zirconyl nitrate with NaL(OEt) in 3.5 M sulfuric acid afforded [(L(OEt))(2)Zr(NO(3))][L(OEt)Zr(SO(4))(NO(3))] (10). Reaction of ZrCl(4) in 1.8 M sulfuric acid with NaL(OEt) in the presence Na(2)SO(4) gave the mu-sulfato-bridged complex [L(OEt)Zr(SO(4))(H(2)O)](2)(mu-SO(4)) (11). Treatment of 11 with triflic acid afforded [(L(OEt))(2)Zr][OTf](2) (12), whereas reaction of 11 with Ag(OTf) afforded a mixture of 12 and trinuclear [{L(OEt)Zr(SO(4))(H(2)O)}(3)(mu(3)-SO(4))][OTf] (13). The Zr(IV) triflato complex [L(OEt)Zr(OTf)(3)] (14) was prepared by reaction of L(OEt)ZrF(3) with Me(3)SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography.
TL;DR: A competitive indicator displacement assay has been successfully developed for the ratiometric determination of sulfhydryl-containing amino acids and peptides using heterobimetallic donor-acceptor complexes as chemodosimetric ensembles.
Abstract: A competitive indicator displacement assay has been successfully developed for the ratiometric determination of sulfhydryl-containing amino acids and peptides using heterobimetallic donor–acceptor complexes as chemodosimetric ensembles. Chromotropic cis-[ML2(CN)2]
(M = FeII, RuII, OsII; L = diimine) are used as signaling indicators and PtII(DMSO)Cl2 acceptor moiety is used as the receptor for the sulfhydryl-containing analytes. A series of three heterobimetallic donor–acceptor complexes: cis-FeII(bpy)2[CN–PtII(DMSO)Cl2]2
(1), cis-RuII(bpy)2[CN–PtII(DMSO)Cl2]2
(2) and cis-OsII(bpy)2[CN–PtII(DMSO)Cl2]2
(3) are synthesized and characterized by X-ray crystallography. All the three ensembles are able to produce specific colorimetric/fluorimetric responses to sulfhydryl-containing amino acids (cysteine, homocysteine and methionine) as well as the sulfhydryl-containing small peptide glutathione. The mechanism of the competitive displacement assay is evaluated by examining the thermodynamics of formation of the donor–acceptor linkage and adducts between the acceptor metal and the sulfhydryl-containing analytes as well as by systematic variation of the donor and acceptor metals in the chemodosimetric ensembles.
TL;DR: In this paper, the synthesis and thermal, redox and photoluminescence properties of a soluble donor-acceptor polyplatin with the electron-accepting silole ring and its model compound are described.
Abstract: The synthesis and thermal, redox and photoluminescence properties of a soluble donor-acceptor polyplatinayne with the electron-accepting silole ring and its model compound are described. The polymer has an optical band gap of 2.10 eV which is much lower than that of thienyl- or silyl-bridged congeners. The incorporation of electron-accepting silole unit in the metallopolymer main chain creates a new π-conjugated system that features unique donor-acceptor characteristics.
TL;DR: A thermally stable platinum polyyne polymer incorporating carbazole-based linking units was prepared by polycondensation polymerization of trans-[PtCl2(PBu3)2] with H−C≡CC≡CRC≡ CC≡ C−H as mentioned in this paper.
Abstract: A thermally stable platinum(II) polyyne polymer incorporating carbazole-based linking units, trans-[–Pt(PBu3)2C≡CC≡CRC≡CC≡C–]
n
(R = 9-butylcarbazole-3,6-diyl), was prepared by polycondensation polymerization of trans-[PtCl2(PBu3)2] with H–C≡CC≡CRC≡CC≡C–H. We report the optical absorption and photoluminescence spectra of this carbon-rich metallopolymer and compare its photophysics with its molecular dinuclear model complex trans-[Pt(Ph)(PEt3)2C≡CC≡CRC≡CC≡CPt(Ph)(PEt3)2] as well as the group 11 gold(I) congener, [(PPh3)AuC≡CC≡CRC≡CC≡CAu(PPh3)]. Characterization of the polymer and metal complexes was accomplished by FT-IR and NMR spectroscopies and FAB mass spectrometry. Our investigations showed that harvesting of the organic triplet emissions can be achieved by the heavy-atom effect of Pt and Au centers, which enables a very high efficiency of intersystem crossing from the S1 singlet excited state to the T1 triplet excited state. The influence of the metal and the C≡C chain length on the intersystem crossing rate and the spatial extent of singlet and triplet excitons is characterized. The present work indicates that high-energy triplet states intrinsically give more efficient phosphorescence in metal-containing diethynylcarbazole systems than in the corresponding bis(butadiynyl) congeners and can thus enhance the radiative decay pathway.
TL;DR: In this article, a number of bicyclic chiral sultams were synthesized based on 1,3-dipolar cycloaddition reactions of nitrile oxides and nitrones with prop-1-ene-1, 3-sultone.
Abstract: A number of bicyclic chiral sultams were synthesized based on 1,3-dipolar cycloaddition reactions of nitrile oxides and nitrones with prop-1-ene-1,3-sultone. The corresponding N-enoyl sultams were prepared by acylation. Their relative effectiveness as new chiral auxiliaries in asymmetric synthesis was evaluated for the asymmetric Diels–Alder reactions with cyclopentadiene. Good chemical yield and excellent endo selectivity were observed. The relationship between the structure and their effectiveness in promoting asymmetric induction of the synthetic chiral sultams was investigated.
TL;DR: In the presence of air, the interaction of AgSO3CF3 with phosphorus-nitrogen π-electron-rich compounds ArC( NPPh2)[N(SiMe3)2] (Ar = phenyl, p-tolyl, 4-pyridyl, 3-polymorphic and 2-polycyclic) and 1,4-C6H4{C(NPPh2[N(Me3)]2]}2 in acetonitrile led to the formation of metallic silver and the oxidative cleavage product {[
TL;DR: In this paper, a group 12 mercury polyyne polymers containing derivatized benzene spacers were prepared in good yields using Hagihara's dehydrohalogenation reaction of HgCl2 with HC≡C(C6H2R)2C≡CH (R = 4,5-dioctyloxy, 2,5 dihexadecyloxy) at room temperature in a basic medium.
Abstract: Group 12 mercury(ii) polyyne polymers containing derivatized benzene spacers were prepared in good yields using Hagihara’s dehydrohalogenation reaction of HgCl2 with HC≡C(C6H2R)2C≡CH (R = 4,5-dioctyloxy, 2,5-dihexadecyloxy) at room temperature in a basic medium. The structures of these polymers were confirmed by standard spectroscopic methods and their luminescent properties were examined. Our investigations indicate that two polymers exhibit different luminescence properties due to different position of the substituents on the benzene spacer.
TL;DR: In this article, the X-ray crystal structures of diruthenium compounds were determined by spectroscopic methods and their optical absorption and emission spectra were correlated to the DFT calculations.
Abstract: Thermal reaction of [Ru2(CO)6(μ-PFu2)(μ-η1,η2-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh2) produces a novel diruthenium complex [Ru2(CO)5(μ-PFu2)(μ-η1,η1,η2-C14H8PPh2)] (1) in good yield whereas the corresponding reaction between [(μ-H)4Ru4(CO)12] and AnPPh2 gives [HRu(CO)3(PPh2C14H8)][(μ-H)4Ru4(CO)11(AnPPh2)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh2 functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru–C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru–Ru bonds, and the making of a Ru–P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.
TL;DR: In this paper, the isomers of epoxides 15-28 are obtained in high yield and moderate to high optical purity when N-enoylsultams 1-14 incorporating a variety of chiral sultams as the chiral induction elements are treated with urea-hydrogen peroxide/trifluoroacetic anhydride.
Abstract: Diastereomeric isomers of epoxides 15-28 are obtained in high yield and moderate to high optical purity when N-enoylsultams 1-14 incorporating a variety of chiral sultams as the chiral induction elements are treated with urea-hydrogen peroxide/trifluoroacetic anhydride.
TL;DR: The synthesis, spectroscopic characterization and X-ray crystal structure of a new chiral triosmium alkylidyne carbonyl cluster, (R,S)-[Os3(μ-H)2(CO)9{μ3-CPPh2(η5-C5H4)Fe(ε5- C5H3(PPh2)CH(Me)NMe2)}] (1) are described.
Abstract: : The synthesis, spectroscopic characterization and X-ray crystal structure of a new chiral triosmium alkylidyne carbonyl cluster, ( R , S )-[Os 3 (µ-H) 2 (CO) 9 {µ 3 -CPPh 2 (η 5 -C 5 H 4 )Fe(η 5 -C 5 H 3 (PPh 2 )CH(Me)NMe 2 )}] ( 1 ) are described. Compound 1 crystallizes in the non-centrosymmetric space group P 2 1 and its absolute configuration has been established. The structure consists of an Os 3 C metal core with one of the PPh 2 moieties of the chiral ferrocenylphosphine bonded to the apical alkylidyne carbon atom to give a zwitterionic cluster complex, reminiscent of the phosphorus ylide. Keywords: Alkylidyne, Chirality, Ferrocene, Metal Cluster, Osmium. Introduction A non-centrosymmetric crystal packing of molecules is a prerequisite for second-order non-linear optical (NLO) activity and much attention has been focused on this aspect of molecular structure [1]. Introduction of a chiral centre ensures that a molecule lacks a centre of symmetry, and this is usually a favorable condition for non-centric crystal structures. In this regard, the production of chiral transition metal clusters is crucial as part of the development of useful organometallic materials, and optically active phosphines containing chiral substituents seem to be promising candidates to promote crystallization in a non-centrosymmetric fashion. The reactivity of optically active diphosphine ligands such as Ph
TL;DR: Chiral secondary amines of the 3,4-dimethoxyphenylethyl and the tryptamine system were reacted with chiral acetylenic sulfoxides and achiral acyclic sulfone as discussed by the authors.
Abstract: Chiral secondary amines of the 3,4-dimethoxyphenylethyl and the tryptamine system were reacted with chiral acetylenic sulfoxides and achiral acetylenic sulfone. In the case of 3,4-dimethoxyphenylethyl amine, much improved diastereoselectivity (96 : 4) was observed as compared to the reaction of achiral secondary amine with chiral acetylenic sulfoxides.
TL;DR: In this article, linear and angular benzobisoxadisiloles 14 and 16 can serve as the precursors for stepwise generations of the syntetic equivalents of 1,4- and 1,3-benzdiynes.
Abstract: Linear and angular benzobisoxadisiloles 14 and 16 can serve as the precursors for stepwise generations of the syntetic equivalents of 1,4- and 1,3-benzdiynes. Benzynes generated were trapped as [4+2] cycloaddition products. Two identical or different rings can be fused to the benzdiyne equivalents. Highly substituted arenes were obtained by removing the oxygen bridges from the furan adducts. The synthesis of naphthoxadisilole 28, which can serve as the precursor of 2,3-naphthyne, is also described.