Synthesis, structure, aggregation-induced emission, self-assembly, and electron mobility of 2,5-bis(triphenylsilylethynyl)-3,4-diphenylsiloles.

2,5-Bis(triphenylsilylethynyl)-3,4-diphenylsiloles with different 1,1-substituents [XYSi(CPh)(2) (C-C≡C-SiPh(3))(2)] (Ph=phenyl) were synthesized in high yields by the Sonogashira coupling of 2,5-dibromo-3,4-diphenylsiloles with triphenylsilylacetylene, and two of these were characterized crystallographically. Crystal structures and theoretical calculations showed that the new silole molecules had higher conjugation than 2,5-diarylsiloles. They possessed low HOMO and LUMO energy levels due to the electron-withdrawing effect of the triphenylsilylethynyl groups. Cyclic voltammetry analysis revealed low electron affinities, which were comparable to those of perfluoroarylsiloles. B3LYP/6-31* calculations demonstrated that the new siloles possessed large reorganization energies for electron and hole transfers and high electron mobilities. A mobility of up to 1.2×10(-5) cm(2) V(-1) s(-1) was obtained by the transient electroluminescence method, which was about fivefold higher than that of tris(8-hydroxyquinolinato)aluminum, a widely used electron-transport material, under the same conditions. All of the silole molecules possessed high thermal stability. Although, their solutions were weakly emissive, their nanoparticle suspensions and thin films emitted intense blue-green light upon photoexcitation, demonstrating a novel feature of aggregation-induced emission (AIE). Polarized emissions were observed in the silole crystals. The addition of solvents, which did not dissolve the silole molecules, into silole-containing solutions caused self-assembly of the molecules, which produced macroscopic fibrils with strong light emissions.

[1]  K. Tamao,et al.  Group 14 Metalloles with Thienyl Groups on 2,5-Positions: Effects of Group 14 Elements on Their π-Electronic Structures† , 1998 .

[2]  Xinping Zhang,et al.  Organic crystal fibers aligned into oriented bundles with polarized emission. , 2007, The journal of physical chemistry. B.

[3]  Weidong Yang,et al.  Linearly Polarized Emission from Colloidal Semiconductor Quantum Rods , 2001, Science.

[4]  Takakazu Yamamoto,et al.  Syntheses of New Alternating CT-Type Copolymers of Thiophene and Pyrido[3,4-b]pyrazine Units: Their Optical and Electrochemical Properties in Comparison with Similar CT Copolymers of Thiophene with Pyridine and Quinoxaline , 1999 .

[5]  Jigang Zhou,et al.  Tuning of electrogenerated silole chemiluminescence. , 2008, Angewandte Chemie.

[6]  A. Ajayaghosh,et al.  Self-assembly of oligo(para-phenylenevinylene)s through arene-perfluoroarene interactions: pi gels with longitudinally controlled fiber growth and supramolecular exciplex-mediated enhanced emission. , 2008, Chemistry.

[7]  Chao-Ping Hsu,et al.  Charge transport properties of tris(8-hydroxyquinolinato)aluminum(III): why it is an electron transporter. , 2005, Journal of the American Chemical Society.

[8]  Rudolph A. Marcus,et al.  Electron transfer reactions in chemistry. Theory and experiment , 1993 .

[9]  K. Tamao,et al.  Silole-containing σ- and π-conjugated compounds , 1998 .

[10]  Ian D. Williams,et al.  Making silole photovoltaically active by attaching carbazolyl donor groups to the silolyl acceptor core. , 2005, Chemical communications.

[11]  Lei Wang,et al.  Highly fluorescent rigid supramolecular polymeric nanowires constructed through multiple hydrogen bonds. , 2009, Journal of the American Chemical Society.

[12]  M. Sartin,et al.  Electrochemistry, spectroscopy, and electrogenerated chemiluminescence of silole-based chromophores. , 2006, Journal of the American Chemical Society.

[13]  Wei Zhao,et al.  Electron affinities of 1,1-diaryl-2,3,4,5-tetraphenylsiloles: direct measurements and comparison with experimental and theoretical estimates. , 2005, Journal of the American Chemical Society.

[14]  Toshimi Shimizu,et al.  Supramolecular nanotube architectures based on amphiphilic molecules. , 2005, Chemical reviews.

[15]  David Cahen,et al.  Electron Energetics at Surfaces and Interfaces: Concepts and Experiments , 2003 .

[16]  T. Yamabe,et al.  Silole-Containing .pi.-Conjugated Systems. 3.1 A Series of Silole-Thiophene Cooligomers and Copolymers: Synthesis, Properties, and Electronic Structures , 1995 .

[17]  Hoi Sing Kwok,et al.  Functionalized Siloles: Versatile Synthesis, Aggregation‐Induced Emission, and Sensory and Device Applications , 2009 .

[18]  Yong Ding,et al.  Single-Crystal Nanorings Formed by Epitaxial Self-Coiling of Polar Nanobelts , 2004, Science.

[19]  B. Tang,et al.  Theoretical study of substituent effect on the charge mobility of 2,5-bis(trialkylsilylethynyl)-1,1,3,4-tetraphenylsiloles , 2010 .

[20]  Ian D. Williams,et al.  Structural control of the photoluminescence of silole regioisomers and their utility as sensitive regiodiscriminating chemosensors and efficient electroluminescent materials. , 2005, The journal of physical chemistry. B.

[21]  Christoph Janiak,et al.  A critical account on π–π stacking in metal complexes with aromatic nitrogen-containing ligands , 2000 .

[22]  Makoto Shiozaki,et al.  Thiophene-silole cooligomers and copolymers , 1992 .

[23]  Michael J Sailor,et al.  Detection of TNT and Picric Acid on Surfaces and in Seawater by Using Photoluminescent Polysiloles. , 2001, Angewandte Chemie.

[24]  Chin‐Ti Chen,et al.  Blue Light-Emitting Devices Based on Molecular Glass Materials of Tetraphenylsilane Compounds** , 2001 .

[25]  Ben Zhong Tang,et al.  Aggregation-enhanced emissions of intramolecular excimers in disubstituted polyacetylenes. , 2008, The journal of physical chemistry. B.

[26]  Yongqiang Dong,et al.  Vapochromism and Crystallization-Enhanced Emission of 1,1-Disubstituted 2,3,4,5-Tetraphenylsiloles , 2007 .

[27]  Ben Zhong Tang,et al.  Synthesis, Light Emission, Nanoaggregation, and Restricted Intramolecular Rotation of 1,1-Substituted 2,3,4,5-Tetraphenylsiloles , 2003 .

[28]  Chin‐Ti Chen,et al.  Optimization of high-performance blue organic light-emitting diodes containing tetraphenylsilane molecular glass materials. , 2002, Journal of the American Chemical Society.

[29]  Huisheng Peng,et al.  Hierarchical Assembly of Organic/Inorganic Building Molecules with π–π Interactions , 2008 .

[30]  J. Brédas,et al.  Electronic properties of silole-based organic semiconductors. , 2004, The Journal of chemical physics.

[31]  J. Ohshita,et al.  Polymeric Organosilicon Systems. 28. Preparation and Properties of Novel σ-π Conjugated Polymers with Alternating Disilanylene and 2,5-Diethynylenesilole Units in the Backbone , 1998 .

[32]  Evidence of environmental strains on charge injection in silole based organic light emitting diodes. , 2007, 0711.1805.

[33]  S. Jenekhe,et al.  Regioregular head-to-tail poly(4-alkylquinoline)s: Synthesis, characterization, self-organization, photophysics, and electroluminescence of new n-type conjugated polymers , 2003 .

[34]  P. Pickup,et al.  Comparison of geometries and electronic structures of polyacetylene, polyborole, polycyclopentadiene, polypyrrole, polyfuran, polysilole, polyphosphole, polythiophene, polyselenophene and polytellurophene , 1998 .

[35]  Yongqiang Dong,et al.  Endowing hexaphenylsilole with chemical sensory and biological probing properties by attaching amino pendants to the silolyl core , 2007 .

[36]  Jong Won Chung,et al.  A Thermoreversible and Proton-Induced Gel−Sol Phase Transition with Remarkable Fluorescence Variation , 2008 .

[37]  Manabu Uchida,et al.  Silole Derivatives as Efficient Electron Transporting Materials , 1996 .

[38]  E. W. Meijer,et al.  About Supramolecular Assemblies of π-Conjugated Systems , 2005 .

[39]  Massimo Malagoli,et al.  The vibrational reorganization energy in pentacene: molecular influences on charge transport. , 2002, Journal of the American Chemical Society.

[40]  J. Michl,et al.  Matrix isolation of silacyclopentadienes: UV-visible and IR spectra and photochemical interconversion , 1994 .

[41]  F. Würthner,et al.  Highly fluorescent lyotropic mesophases and organogels based on J-aggregates of core-twisted perylene bisimide dyes. , 2008, Chemistry.

[42]  Ling Zang,et al.  One-dimensional self-assembly of planar pi-conjugated molecules: adaptable building blocks for organic nanodevices. , 2008, Accounts of chemical research.

[43]  Jong Won Chung,et al.  Self-assembled perpendicular growth of organic nanoneedles via simple vapor-phase deposition: one-step fabrication of a superhydrophobic surface. , 2008, Chemical communications.

[44]  Zakya H. Kafafi,et al.  Efficient organic light-emitting diodes with undoped active layers based on silole derivatives , 2002 .

[45]  A. Facchetti,et al.  Dithienosilole- and dibenzosilole-thiophene copolymers as semiconductors for organic thin-film transistors. , 2006, Journal of the American Chemical Society.

[46]  Moon Soo Choi,et al.  Gelation-induced fluorescence enhancement of benzoxazole-based organogel and its naked-eye fluoride detection. , 2008, Chemical communications.

[47]  K. Tamao,et al.  Modification of the electronic structure of silole by the substituents on the ring silicon , 1998 .

[48]  Jincai Zhao,et al.  Detection of explosives with a fluorescent nanofibril film. , 2007, Journal of the American Chemical Society.

[49]  Manabu Uchida,et al.  Structural optimization of 2,5-diarylsiloles as excellent electron-transporting materials for organic electroluminescent devices , 2001 .

[50]  Z. Lao,et al.  Reorganization Energies in the Transports of Holes and Electrons in Organic Amines in Organic Electroluminescence Studied by Density Functional Theory , 2003 .

[51]  Shui-Tong Lee,et al.  A dinuclear aluminum 8-hydroxyquinoline complex with high electron mobility for organic light-emitting diodes , 2003 .

[52]  X. Tong,et al.  Fluorescent Liquid‐Crystal Gels with Electrically Switchable Photoluminescence , 2006 .

[53]  Andrew J Boydston,et al.  A controlled, iterative synthesis and the electronic properties of oligo[(p-phenyleneethynylene)-alt-(2,5-siloleneethynylene)]s. , 2004, Journal of the American Chemical Society.

[54]  F. Huang,et al.  Conjugated Fluorene and Silole Copolymers: Synthesis, Characterization, Electronic Transition, Light Emission, Photovoltaic Cell, and Field Effect Hole Mobility , 2005 .

[55]  S. Kang,et al.  Spiro-silacycloalkyl tetraphenylsiloles with a tunable exocyclic ring : Preparation, characterization, and device application of 1,1'-silacycloalkyl-2,3,4,5-tetraphenylsiloles , 2007 .

[56]  Rudolph A. Marcus,et al.  On the Theory of Oxidation‐Reduction Reactions Involving Electron Transfer. I , 1956 .

[57]  Z. Kafafi,et al.  Electronic structure of a silole derivative-magnesium thin film interface , 2004 .

[58]  B. Tang,et al.  Highly efficient organic light-emitting diodes with a silole-based compound , 2002 .

[59]  Daoben Zhu,et al.  Efficient blue emission from siloles , 2001 .

[60]  Daoben Zhu,et al.  Structures, electronic states, photoluminescence, and carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles. , 2005, Journal of the American Chemical Society.

[61]  Yongqiang Dong,et al.  Vapochromism of Hexaphenylsilole , 2005 .

[62]  Deqing Zhang,et al.  A fluorescence turn-on detection of cyanide in aqueous solution based on the aggregation-induced emission. , 2009, Organic letters.

[63]  Kaushik Balakrishnan,et al.  Linearly polarized emission of an organic semiconductor nanobelt. , 2006, The journal of physical chemistry. B.

[64]  Rudolph A. Marcus,et al.  Chemical and Electrochemical Electron-Transfer Theory , 1964 .

[65]  A. Kahn,et al.  Controlled p doping of the hole-transport molecular material N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine with tetrafluorotetracyanoquinodimethane , 2003 .

[66]  Yong Cao,et al.  Synthesis and Optoelectronic Properties of Random Copolymers Derived from Fluorene and 2,5-Bis(2,1,3-benzothiadiazolyl)silole , 2007 .

[67]  S. Barlow,et al.  Comparative studies of the geometric and electronic properties of 1,1-disubstituted-2,3,4,5-tetraphenylsiloles and 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disila-3,5-cyclohexadiene , 2006 .

[68]  T. Deng,et al.  Polarized photoluminescence from poly(p-phenylene-ethynylene) via a block copolymer nanotemplate. , 2003, Journal of the American Chemical Society.

[69]  Neal R. Armstrong,et al.  Electrochemistry and Electrogenerated Chemiluminescence Processes of the Components of Aluminum Quinolate/Triarylamine, and Related Organic Light-Emitting Diodes , 1998 .

[70]  W. Trogler,et al.  Synthesis, Luminescence Properties, and Explosives Sensing with 1,1-Tetraphenylsilole- and 1,1-Silafluorene-vinylene Polymers , 2007 .

[71]  Andrew J Boydston,et al.  Improving quantum efficiencies of siloles and silole-derived butadiene chromophores through structural tuning. , 2004, Angewandte Chemie.

[72]  Yong Ding,et al.  Conversion of Zinc Oxide Nanobelts into Superlattice-Structured Nanohelices , 2005, Science.

[73]  T. Tilley,et al.  Synthesis and characterization of perfluoroaryl-substituted siloles and thiophenes : A series of electron-deficient blue light emitting materials , 2006 .

[74]  Andrew J Boydston,et al.  Synthesis and electronic properties of donor-acceptor pi-conjugated siloles. , 2004, Journal of the American Chemical Society.

[75]  Tobin J Marks,et al.  Building blocks for n-type organic electronics: regiochemically modulated inversion of majority carrier sign in perfluoroarene-modified polythiophene semiconductors. , 2003, Angewandte Chemie.

[76]  K. Tamao,et al.  Theoretical Study of the Electronic Structure of 2,2'-Bisilole in Comparison with 1,1'-Bi-1,3-cyclopentadiene : σ^*-π^* Conjugation and a Low-Lying LUMO as the Origin of the Unusual Optical Properties of 3,3',4,4'-Tetraphenyl-2,2'-bisilole^ , 1996 .

[77]  H S Kwok,et al.  Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole. , 2001, Chemical communications.

[78]  Yongfeng Zhou,et al.  Supramolecular Self-Assembly of Macroscopic Tubes , 2004, Science.

[79]  Ben Zhong Tang,et al.  Structural modulation of solid-state emission of 2,5-bis(trialkylsilylethynyl)-3,4-diphenylsiloles. , 2009, Angewandte Chemie.

[80]  Yang Yang,et al.  Fluorescent conjugated dendrimers with fluorinated terminal groups: nanofiber formation and electroluminescence properties. , 2008, Organic letters.

[81]  K. Ng,et al.  Synthesis of an AIE-active fluorogen and its application in cell imaging , 2009 .

[82]  Yamaguchi,et al.  Toward new materials for organic electroluminescent devices: synthesis, structures, and properties of a series of 2,5-diaryl-3,4-diphenylsiloles , 2000, Chemistry.

[83]  Jong Won Chung,et al.  Highly fluorescent supramolecular gels with chirality transcription through hydrogen bonding. , 2008, Chemical communications.

[84]  Rainer F. Mahrt,et al.  Efficient two layer leds on a polymer blend basis , 1995 .

[85]  B. Tang,et al.  Steric Hindrance, Electronic Communication, and Energy Transfer in the Photo- and Electroluminescence Processes of Aggregation-Induced Emission Luminogens , 2010 .

[86]  Massimo Malagoli,et al.  Density functional theory study of the geometric structure and energetics of triphenylamine-based hole-transporting molecules , 2000 .

[87]  G. Malliaras,et al.  Non-dispersive and air-stable electron transport in an amorphous organic semiconductor , 2001 .