Synthesis, optical properties and supramolecular order of π-conjugated 2,5-di(alcoxy)phenyleneethynylene oligomers

Abstract Two series of 2,5-di(alkoxy)phenyleneethynylene oligomers were synthesized by Sonogashira–Heck coupling reaction. The chemical structure was corroborated by 1H, 13C, APT, DEPT-135 NMR, Raman, FTIR and MALDI-TOF mass spectrometry. The chemical structure of the molecules has been varied in order to study the effect on the physicochemical and optoelectronic properties of the different chain lengths of the lateral substituents (dodecanoxy and butoxy), of different terminal groups (H, Br and I), of different chain length (3, 5 and 7 repeat units in the main conjugated backbone). The thermal properties were analyzed by DSC, TGA and by temperature-dependent X-ray diffraction. The diffraction studies of the oligomers revealed a crystalline behavior for the butoxy series, while for the dodecanoxy series the X-ray patterns are consistent with a supramolecular organization formed of randomly distributed crystalline domains that exhibit a periodic structure at small angles, indicating the presence of a lamellar order. The optical properties can be modulated within a series by increasing the length of the conjugated oligomer chain. On the contrary, neither the length of the alkoxy substituents nor the terminal groups have effect on the shape of the absorption and emission spectra.

[1]  I. Leray,et al.  Novel fluorophores: efficient synthesis and photophysical properties. , 2004, Organic letters.

[2]  Jeffrey S. Moore,et al.  Synthesis of rigid dendritic macromolecules: enlarging the repeat unit size as a function of generation, permitting growth to continue , 1991 .

[3]  J. Claridge,et al.  Poly(p-phenyleneethynylene)s Are Thermotropic Liquid Crystalline† , 1999 .

[4]  J. Nunzi,et al.  Oligo(phenylethynylene) as a High Photoluminescence Quantum Yield Material and Its Distributed Feedback Laser Emission in Thin Films , 2002 .

[5]  James M. Tour,et al.  Convergent Synthetic Routes to Orthogonally Fused Conjugated Oligomers Directed toward Molecular Scale Electronic Device Applications. , 1996, The Journal of organic chemistry.

[6]  D. Yaron,et al.  Modeling the effects of torsional disorder on the spectra of poly- and oligo-(p-phenyleneethynylenes). , 2006, The journal of physical chemistry. B.

[7]  Prashant V Kamat,et al.  Singlet and triplet excited-state interactions and photochemical reactivity of phenyleneethynylene oligomers. , 2006, The journal of physical chemistry. A.

[8]  Gerhard Wegner,et al.  Electronic Materials: The Oligomer Approach , 1998 .

[9]  Tsuyoshi Kawai,et al.  Electroluminescence in conducting polymers based on poly(phenylene ethynylene) , 1997 .

[10]  Christoph Weder,et al.  Efficient Solid-State Photoluminescence in New Poly(2,5-dialkoxy-p-phenyleneethynylene)s , 1996 .

[11]  S. Luzzati,et al.  Rigid rod conjugated polymers for nonlinear optics: 1. Characterization and linear optical properties of poly(aryleneethynylene) derivatives , 1994 .

[12]  M. Myrick,et al.  Band Gap Engineering of Poly(p-phenyleneethynylene)s: Cross-Conjugated PPE−PPV Hybrids , 2002 .

[13]  Jeffrey S. Moore,et al.  Improvements in the Synthesis of Phenylacetylene Monodendrons Including a Solid-Phase Convergent Method , 1995 .

[14]  P. Kamat,et al.  Excited-state and photoelectrochemical behavior of pyrene-linked phenyleneethynylene oligomer. , 2008, The journal of physical chemistry. B.

[15]  Jean-Yves Bigot,et al.  Rigid Rod Conjugated Polymers for Nonlinear Optics. 3. Intramolecular H Bond Effects on Poly(phenyleneethynylene) Chains , 1997 .

[16]  R. Tykwinski,et al.  Oligomeric and polymeric systems with a cross-conjugated pi-framework. , 2006, Chemical reviews.

[17]  C. Amatore,et al.  Intimate mechanism of oxidative addition to zerovalent palladium complexes in the presence of halide ions and its relevance to the mechanism of palladium-catalyzed nucleophilic substitutions , 1993 .

[18]  I. Moggio,et al.  Amphiphilic phenyl-ethynylene polymers and copolymers. Synthesis, characterization, and optical emission properties , 2003 .

[19]  A. R. Williams,et al.  Relative fluorescence quantum yields using a computer-controlled luminescence spectrometer , 1983 .

[20]  E. Arias,et al.  Amphiphilic phenylene-ethynylene polymers and oligomers for polarized electroluminescence , 2002 .

[21]  H. A. Dieck,et al.  Palladium catalyzed synthesis of aryl, heterocyclic and vinylic acetylene derivatives , 1975 .

[22]  U. Bunz,et al.  Poly(aryleneethynylene)s: Syntheses, Properties, Structures, and Applications. , 2000, Chemical reviews.

[23]  J. Tour,et al.  Rapid Syntheses of Oligo(2,5-thiophene ethynylene)s with Thioester Termini: Potential Molecular Scale Wires with Alligator Clips , 1997 .

[24]  D. Powell,et al.  Poly((2,5-dialkoxy-p-phenylene)ethynylene-p-phenyleneethynylene)s and Their Model Compounds , 1998 .

[25]  F. E. Karasz,et al.  A Processible Poly(phenyleneethynylene) with Strong Photoluminescence: Synthesis and Characterization of Poly[(m-phenyleneethynylene)-alt- (p-phenyleneethynylene)] , 1998 .

[26]  Thomas M. Cooper,et al.  Photophysical Characterization of a Series of Platinum(II)-Containing Phenyl-Ethynyl Oligomers , 2002 .

[27]  A. Godt,et al.  Synthesis and Characterization of Monodisperse Oligo(phenyleneethynylene)s , 1997 .

[28]  E. Arias,et al.  Dodecanoxy-phenylethynylene oligomers for light emitting diodes , 2004 .

[29]  Ke Jia,et al.  Theoretical study of spectroscopic properties of dimethoxy-p-phenylene-ethynylene oligomers: planarization of the conjugated backbone. , 2007, The journal of physical chemistry. A.

[30]  I. B. Berlman.  Handbook of flourescence spectra of aromatic molecules , 1971 .

[31]  C. Suresh,et al.  Photophysical and theoretical investigations of oligo(p-phenyleneethynylene)s: effect of alkoxy substitution and alkyne-aryl bond rotations. , 2006, The journal of physical chemistry. A.

[32]  J. Bigot,et al.  Rigid Rod Conjugated Polymers for Nonlinear Optics. 2. Synthesis and Characterization of Phenylene−Ethynylene Oligomers , 1996 .

[33]  T. Swager,et al.  Fluorescent Porous Polymer Films as TNT Chemosensors: Electronic and Structural Effects , 1998 .

[34]  Jean-Michel Nunzi,et al.  Amphiphilic Phenylene−Ethynylene Oligomers in Langmuir−Blodgett Films. Self-Assembling Multilayers for Electroluminescent Devices , 2000 .

[35]  J. Tour,et al.  Iterative Divergent/Convergent Approach to Linear Conjugated Oligomers by Successive Doubling of the Molecular Length: A Rapid Route to a 128Å‐Long Potential Molecular Wire , 1994 .