Irradiation of 4-chloroanilines in the presence of alkenes gives 4-(2%-chloroalkyl)-anilines. Whe... more Irradiation of 4-chloroanilines in the presence of alkenes gives 4-(2%-chloroalkyl)-anilines. When the irradiation is carried out in the presence of NaBH 4 , 4-alkylanilines are obtained directly. The reaction appears to occur via the corresponding phenyl cation.
ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from so... more ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from soln. These films were doped by treatment with iodine or DDQ and their cond. detd. by elec. measurements. The iodine doped polymer films show conductivities of up to 0.35 S/cm but the conductivities decreased on standing due to reversible dedoping of the films. Polymers doped with DDQ are more stable and conductivities up to 1.1 S/cm are reported. The doped polymers show little absorption in the visible region of the spectrum, suggesting possible applications in plastic electronics. [on SciFinder (R)]
ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from so... more ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from soln. These films were doped by treatment with iodine or DDQ and their cond. detd. by elec. measurements. The iodine doped polymer films show conductivities of up to 0.35 S/cm but the conductivities decreased on standing due to reversible dedoping of the films. Polymers doped with DDQ are more stable and conductivities up to 1.1 S/cm are reported. The doped polymers show little absorption in the visible region of the spectrum, suggesting possible applications in plastic electronics. [on SciFinder (R)]
A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units wa... more A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units was prepared by the Cassar-Heck-Sonogashira cross-coupling reaction. Its electroluminescence was tested in a device, and its fluorescence colour could be tuned by light-induced norbornadiene-quadricyclane isomerization.
Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanion... more Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanionic bisphosphinoaryl ligands [C 6 H 3 (CH 2 PR 2 ) 2 -2,6] -(PCP) (R ) Ph (11); iPr (12)) and 2,2′:6′,2′′-terpyridine, have been synthesized by two different synthetic pathways in good yields. The molecular structure in the solid state of [Ru{C 6 H 2 (CH 2 PPh 2 ) 2 -2,6}(tpy)](OTf) (14) has been determined by X-ray crystallography. The spectroscopic and electrochemical properties of the [Ru(PCP)(tpy)]Cl complexes were compared with those obtained for [Ru{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}(tpy)](Cl) (3) containing the monoanionic bisaminoaryl ligand [C 6 H 3 (CH 2 NMe 2 ) 2 -2,6] -(NCN). The obtained results revealed that substitution of the NCNpincer ligand by PCP-pincer ligands offers a powerful tool to tune the redox and photophysical properties as well as the reactivity of the ruthenium(II) metal centers in the resulting photoactive monomeric species. . (1) (a) Sauvage, J.-P.; Collin, J.-P.; Chambron, J.-C.; Guillerez, S.; Coudret, C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Lloris, J. M.; Martínez-Máñ ez, R.; Benito, A.; Soto, J.; Pardo, T.; Miranda, M. A.; Markos, M. D. Eur. J. Inorg. Chem. 2000, 741. (g) Constable, E. C.; Housecroft, C. E.; Johnston, L. A.; Armspach, D.; Neuburger, M.; Zehnder, M. Polyhedron 2001, 20, 483. (h) Maestri, M.; Armaroli, N.; Balzani, V.; Constable, E. C.; Cargill Thompson, A. M. W. Inorg. Chem. 1995Chem. , 34, 2759 (2) Juris, A.; Balzani, V.; Barigelletti, F.; Campagna, S.; Belser, P.; von Zelensky, A. Coord. Chem. Rev. 1998, 84, 85. (3) (a) Hissel, M.; El-Ghayoury, A.; Harriman, A.; Ziessel, R. Angew. (5) (a) Padilla-Tosta, M. E.; Lloris, J. M.; Martínez-Máñ ez, Pardo, T.; Soto, J.; Benito, A.; Markos, M. D. Inorg. Chem. Commun. 2000, 3, 45. (b) Beley, M.; Collin, J.-P.; Sauvage, J.-P. Inorg. Chem. 1993, 32, 4539. (c) Collin, J.-P.; Gaviñ a, P.; Heitz, V.; Sauvage, J.-P Eur.
A formulation including dissolved phosphorescent iridium complex has been synthesised as a resist... more A formulation including dissolved phosphorescent iridium complex has been synthesised as a resist for step and flash imprint lithography (S-FIL TM ). Functional properties of the resist after curing are demonstrated and structures as small as 50 nm have been successfully imprinted with this material onto a 4 in. silicon wafer. Fluorescent microscopy images demonstrate increased fluorescent signals where arrays of nano structures are imprinted. This technique of direct imprinting of functional materials could potentially lead to rapid, high throughput and low-cost fabrication of nanoscale organic devices and circuits.
Three synthetic protocols have been employed to prepare solution-processable poly(4,4dialkylcyclo... more Three synthetic protocols have been employed to prepare solution-processable poly(4,4dialkylcyclopentadithiophenes). These polymers are fused-ring analogues of poly(3-alkylthiophenes) and structural analogues of the polyfluorenes. Oxidative polymerization of 4,4-dialkylcyclopenta[2,1-b;3,4-b′]dithiophenes using iron (III) chloride gave high-molecular-weight polymers, whereas nickel-catalyzed polymerization of the 2,6-dibromo derivatives via in situ-generated thienylmagnesium and thienylzinc reagents gave moderate-molecular-weight polymers. The structures of the polymers were confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry. In the polymerization using organomagnesium intermediates, some chain capping by methyl end groups was observed. This side reaction can be avoided by polymerization of the organozinc reagents. Post-functionalization of the halogen termini of these polymers can be readily achieved using a cross-coupling with an aryl Grignard reagent. The main chain conjugation in these polymers can be directly correlated to the length of the polymer backbone because the UV-vis spectra of fractionated samples show absorption maxima that increase with the average degree of polymerization as determined by GPC, up to a limiting value of ∼20. UV-vis spectroscopy suggests that poly(4,4-dialkylcyclopentadithiophenes) do not self-assemble in the solid state, as has been previously observed for regioregular poly-3-alkylthiophenes.
Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation... more Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation of these rings with UV light in a solution containing isopropyl alcohol as hydrogen donor resulted in a photo-induced reduction of benzophenone to benzopinacol and the formation linked macrocycles. These rings can be heated to undergo ringopening polymerization and produce a polymer network or they can be added to a polycondensation reaction to prepare poly(ether ether ketones) with variable degrees of crosslinking.
Irradiation of 4-chloroaniline or of its N,N-dimethyl derivative in polar solvents generates the ... more Irradiation of 4-chloroaniline or of its N,N-dimethyl derivative in polar solvents generates the corresponding triplet phenyl cations. These are trapped by alkenes yielding arylated products in medium to good yields. B3LYP calculations show that the triplet cation slides with negligible activation energy to a bonded adduct with ethylene, whereas it forms only a marginally stabilized CT complex with water (chosen as a representative sigma nucleophile). The structure of the final products depends on the preferred path from the adduct cation with the alkene. In the case of aryl olefins, this deprotonates to stilbene derivatives, while, from 2,3-dimethyl-2-butene and allytrimethylsilane, allylanilines are obtained by elimination of an electrofugal group in gamma. In the case of mono- and disubstituted alkenes the cation adds chloride rather than eliminating and beta-chloroalkylanilines are obtained. The regio- and sterochemistry of the addition across the alkene are best understood with a phenonium ion structure for the adduct. The nucleophile entering in beta can be varied under conditions in which the adduct cation is trapped more efficiently than the starting phenyl cation. Thus, beta-methoxyalkylanilines are formed when the irradiation is carried out in methanol. beta-Iodoalkylanilines are obtained in acetonitrile containing iodide and unsubstituted alkylanilines in the presence of sodium borohydride. A case of intramolecular nucleophilic trapping is found with 4-pentenoic acid. The reaction is a wide-scope ionic analogue of the radicalic Meerwin arylation of olefins.
J. Mater. Chem., 2002, 12, 2597-2599 DOI:10.1039/B206477D (Communication). New routes to poly(4,4... more J. Mater. Chem., 2002, 12, 2597-2599 DOI:10.1039/B206477D (Communication). New routes to poly(4,4-dialkylcyclopentadithiophene-2,6-diyls). Paolo Coppoa, Domenico C. Cupertinob, Stephen G. Yeatesb and Michael L ...
Neutral heteroleptic mononuclear iridium(III) complexes with (2,4-difluoro)phenylpyridine and dif... more Neutral heteroleptic mononuclear iridium(III) complexes with (2,4-difluoro)phenylpyridine and different pyridine-1,2,4-triazole ligands were synthesized and fully characterized. We investigated the effects of substituents in the 5-position of the triazole ring on the photophysical and electrochemical behavior. Increasing the electron-withdrawing capabilities generally leads to a lowering of the HOMO level with a consequent slight widening of the HOMO− LUMO gap and a blue shift in emission. The complexes reported exhibit high emission quantum yields and long luminescent lifetimes, typical of iridium(III) complexes, and most of them show reversible redox processes in solution. Also, many of the complexes reported here have been obtained as single crystals suitable for X-ray crystallography. Two of the complexes were further tested as phosphorescent dyes in OLED devices and showed high external quantum efficiencies (∼7%) and color points better than the "standard" for blue iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C 2′ ]picolinate (FIrpic). We also report the full electrochemical investigation of FIrpic in different solvents. Baldo, M. A.; O'Brien, D. F.; You, Y.; Shoustikov, A.; Sibley, S.; Thompson, M. E.; Forrest, S. R. Nature 1998, 395, 151-154. (6) Tsuboyama, A.; Iwawaki, H.; Furugori, M.; Mukaide, T.; Kamatani, J.; Igawa, S.; Moriyama, T.; Miura, S.; Takiguchi, T.; Okada, S.; Hoshino, M.; Ueno, K.
A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthes... more A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthesis of a novel terpyridine-pincer (3, TPBr) bridging ligand, 4'-{4-BrC6H2(CH2NMe2)2-3,5}-2,2':6',2' '-terpyridine. Mononuclear species [PdX(TP)] (X = Br, Cl), [Ru(TPBr)(tpy)](PF6)2, and [Ru(TPBr)2](PF6)2, synthesized by selective metalation of the NCNBr-pincer moiety or complexation of the terpyridine of the bifunctional ligand TPBr, were used as building blocks for the preparation of heterodi- and trimetallic complexes [Ru(TPPdCl)(tpy)](PF6)2 (7) and [Ru(TPPdCl)2](PF6)2 (8). The molecular structures in the solid state of [PdBr(TP)] (4a) and [Ru(TPBr)2](PF6)2 (6) have been determined by single-crystal X-ray analysis. Electrochemical behavior and photophysical properties of the mono- and heterometallic complexes are described. All the above di- and trimetallic Ru complexes exhibit absorption bands attributable to (1)MLCT (Ru --> tpy) transitions. For the heteroleptic complexes, the transitions involving the unsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bands observed in the electronic spectra for TPBr and [PdCl(TP)] have been assigned with the aid of TD-DFT calculations. All complexes display weak emission both at room temperature and in a butyronitrile glass at 77 K. The considerable red shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)2]2+ indicates stabilization of the luminescent 3MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopic studies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and 77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetallic complex [Ru(TPPdSCN)(tpy)](PF6)2, are indicative of charge redistribution through the bridging ligand TPBr. The results are in line with a weak coupling between the {Ru(tpy)2} chromophoric unit and the (non)metalated NCN-pincer moiety.
The new fully planar cyclopentadithiophene, 4-n-dodecylidene-4H-cyclopenta(2,1-b;3,4-bA)dithiophe... more The new fully planar cyclopentadithiophene, 4-n-dodecylidene-4H-cyclopenta(2,1-b;3,4-bA)dithiophene, shows extensive p-stacking in the solid state with short intermolecular distances (ca. 3.5 Å) between adjacent molecules. Polymerisation of this monomer by two different protocols gave solution processable alkenyl-bridged cyclopentadithiophene polymers with extended p-conjugation in the main chain.
A number of strategies exist to design molecular materials based on self-assembled peptides and t... more A number of strategies exist to design molecular materials based on self-assembled peptides and their derivatives. These include soft materials based on a variety of structural motifs including coiled-coils, b-sheets, b-hairpins, and peptide amphiphiles. In these systems, the peptide chains usually contain at least ten amino acids. It has been known for some time that using aromatic components in conjunction with peptides allows the use of much smaller peptides by taking advantage of p-stacking interactions. One system that has been illustrated is that of N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF) which forms a hydrogel under physiological conditions. This example and other closely related aromatic short peptide derivatives are known to form fibrous hydrogels that have found applications in biological sensing and cell culture. Understanding of the supramolecular structures formed by these molecules will aid the rational design of new architectures tailored to the needs of specific biological and non-biological applications. However, to date a complete structure has not been proposed for any member of this class of self-assembly systems. Here we apply a number of spectroscopic techniques to Fmoc-FF and construct a model based on the data obtained comprising a new nanocylindrical molecular architecture based on p-p interlocked b-sheets. Transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) was used to confirm the proposed model.
Irradiation of 4-chloroanilines in the presence of alkenes gives 4-(2%-chloroalkyl)-anilines. Whe... more Irradiation of 4-chloroanilines in the presence of alkenes gives 4-(2%-chloroalkyl)-anilines. When the irradiation is carried out in the presence of NaBH 4 , 4-alkylanilines are obtained directly. The reaction appears to occur via the corresponding phenyl cation.
ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from so... more ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from soln. These films were doped by treatment with iodine or DDQ and their cond. detd. by elec. measurements. The iodine doped polymer films show conductivities of up to 0.35 S/cm but the conductivities decreased on standing due to reversible dedoping of the films. Polymers doped with DDQ are more stable and conductivities up to 1.1 S/cm are reported. The doped polymers show little absorption in the visible region of the spectrum, suggesting possible applications in plastic electronics. [on SciFinder (R)]
ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from so... more ABSTRACT Thin films of poly(4,4-dioctylcyclopentadithiophene) were obtained by processing from soln. These films were doped by treatment with iodine or DDQ and their cond. detd. by elec. measurements. The iodine doped polymer films show conductivities of up to 0.35 S/cm but the conductivities decreased on standing due to reversible dedoping of the films. Polymers doped with DDQ are more stable and conductivities up to 1.1 S/cm are reported. The doped polymers show little absorption in the visible region of the spectrum, suggesting possible applications in plastic electronics. [on SciFinder (R)]
A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units wa... more A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units was prepared by the Cassar-Heck-Sonogashira cross-coupling reaction. Its electroluminescence was tested in a device, and its fluorescence colour could be tuned by light-induced norbornadiene-quadricyclane isomerization.
Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanion... more Novel organometallic [Ru(PCP)(tpy)]Cl complexes, containing the terdentate coordinating monoanionic bisphosphinoaryl ligands [C 6 H 3 (CH 2 PR 2 ) 2 -2,6] -(PCP) (R ) Ph (11); iPr (12)) and 2,2′:6′,2′′-terpyridine, have been synthesized by two different synthetic pathways in good yields. The molecular structure in the solid state of [Ru{C 6 H 2 (CH 2 PPh 2 ) 2 -2,6}(tpy)](OTf) (14) has been determined by X-ray crystallography. The spectroscopic and electrochemical properties of the [Ru(PCP)(tpy)]Cl complexes were compared with those obtained for [Ru{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}(tpy)](Cl) (3) containing the monoanionic bisaminoaryl ligand [C 6 H 3 (CH 2 NMe 2 ) 2 -2,6] -(NCN). The obtained results revealed that substitution of the NCNpincer ligand by PCP-pincer ligands offers a powerful tool to tune the redox and photophysical properties as well as the reactivity of the ruthenium(II) metal centers in the resulting photoactive monomeric species. . (1) (a) Sauvage, J.-P.; Collin, J.-P.; Chambron, J.-C.; Guillerez, S.; Coudret, C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Lloris, J. M.; Martínez-Máñ ez, R.; Benito, A.; Soto, J.; Pardo, T.; Miranda, M. A.; Markos, M. D. Eur. J. Inorg. Chem. 2000, 741. (g) Constable, E. C.; Housecroft, C. E.; Johnston, L. A.; Armspach, D.; Neuburger, M.; Zehnder, M. Polyhedron 2001, 20, 483. (h) Maestri, M.; Armaroli, N.; Balzani, V.; Constable, E. C.; Cargill Thompson, A. M. W. Inorg. Chem. 1995Chem. , 34, 2759 (2) Juris, A.; Balzani, V.; Barigelletti, F.; Campagna, S.; Belser, P.; von Zelensky, A. Coord. Chem. Rev. 1998, 84, 85. (3) (a) Hissel, M.; El-Ghayoury, A.; Harriman, A.; Ziessel, R. Angew. (5) (a) Padilla-Tosta, M. E.; Lloris, J. M.; Martínez-Máñ ez, Pardo, T.; Soto, J.; Benito, A.; Markos, M. D. Inorg. Chem. Commun. 2000, 3, 45. (b) Beley, M.; Collin, J.-P.; Sauvage, J.-P. Inorg. Chem. 1993, 32, 4539. (c) Collin, J.-P.; Gaviñ a, P.; Heitz, V.; Sauvage, J.-P Eur.
A formulation including dissolved phosphorescent iridium complex has been synthesised as a resist... more A formulation including dissolved phosphorescent iridium complex has been synthesised as a resist for step and flash imprint lithography (S-FIL TM ). Functional properties of the resist after curing are demonstrated and structures as small as 50 nm have been successfully imprinted with this material onto a 4 in. silicon wafer. Fluorescent microscopy images demonstrate increased fluorescent signals where arrays of nano structures are imprinted. This technique of direct imprinting of functional materials could potentially lead to rapid, high throughput and low-cost fabrication of nanoscale organic devices and circuits.
Three synthetic protocols have been employed to prepare solution-processable poly(4,4dialkylcyclo... more Three synthetic protocols have been employed to prepare solution-processable poly(4,4dialkylcyclopentadithiophenes). These polymers are fused-ring analogues of poly(3-alkylthiophenes) and structural analogues of the polyfluorenes. Oxidative polymerization of 4,4-dialkylcyclopenta[2,1-b;3,4-b′]dithiophenes using iron (III) chloride gave high-molecular-weight polymers, whereas nickel-catalyzed polymerization of the 2,6-dibromo derivatives via in situ-generated thienylmagnesium and thienylzinc reagents gave moderate-molecular-weight polymers. The structures of the polymers were confirmed by NMR spectroscopy and MALDI-TOF mass spectrometry. In the polymerization using organomagnesium intermediates, some chain capping by methyl end groups was observed. This side reaction can be avoided by polymerization of the organozinc reagents. Post-functionalization of the halogen termini of these polymers can be readily achieved using a cross-coupling with an aryl Grignard reagent. The main chain conjugation in these polymers can be directly correlated to the length of the polymer backbone because the UV-vis spectra of fractionated samples show absorption maxima that increase with the average degree of polymerization as determined by GPC, up to a limiting value of ∼20. UV-vis spectroscopy suggests that poly(4,4-dialkylcyclopentadithiophenes) do not self-assemble in the solid state, as has been previously observed for regioregular poly-3-alkylthiophenes.
Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation... more Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation of these rings with UV light in a solution containing isopropyl alcohol as hydrogen donor resulted in a photo-induced reduction of benzophenone to benzopinacol and the formation linked macrocycles. These rings can be heated to undergo ringopening polymerization and produce a polymer network or they can be added to a polycondensation reaction to prepare poly(ether ether ketones) with variable degrees of crosslinking.
Irradiation of 4-chloroaniline or of its N,N-dimethyl derivative in polar solvents generates the ... more Irradiation of 4-chloroaniline or of its N,N-dimethyl derivative in polar solvents generates the corresponding triplet phenyl cations. These are trapped by alkenes yielding arylated products in medium to good yields. B3LYP calculations show that the triplet cation slides with negligible activation energy to a bonded adduct with ethylene, whereas it forms only a marginally stabilized CT complex with water (chosen as a representative sigma nucleophile). The structure of the final products depends on the preferred path from the adduct cation with the alkene. In the case of aryl olefins, this deprotonates to stilbene derivatives, while, from 2,3-dimethyl-2-butene and allytrimethylsilane, allylanilines are obtained by elimination of an electrofugal group in gamma. In the case of mono- and disubstituted alkenes the cation adds chloride rather than eliminating and beta-chloroalkylanilines are obtained. The regio- and sterochemistry of the addition across the alkene are best understood with a phenonium ion structure for the adduct. The nucleophile entering in beta can be varied under conditions in which the adduct cation is trapped more efficiently than the starting phenyl cation. Thus, beta-methoxyalkylanilines are formed when the irradiation is carried out in methanol. beta-Iodoalkylanilines are obtained in acetonitrile containing iodide and unsubstituted alkylanilines in the presence of sodium borohydride. A case of intramolecular nucleophilic trapping is found with 4-pentenoic acid. The reaction is a wide-scope ionic analogue of the radicalic Meerwin arylation of olefins.
J. Mater. Chem., 2002, 12, 2597-2599 DOI:10.1039/B206477D (Communication). New routes to poly(4,4... more J. Mater. Chem., 2002, 12, 2597-2599 DOI:10.1039/B206477D (Communication). New routes to poly(4,4-dialkylcyclopentadithiophene-2,6-diyls). Paolo Coppoa, Domenico C. Cupertinob, Stephen G. Yeatesb and Michael L ...
Neutral heteroleptic mononuclear iridium(III) complexes with (2,4-difluoro)phenylpyridine and dif... more Neutral heteroleptic mononuclear iridium(III) complexes with (2,4-difluoro)phenylpyridine and different pyridine-1,2,4-triazole ligands were synthesized and fully characterized. We investigated the effects of substituents in the 5-position of the triazole ring on the photophysical and electrochemical behavior. Increasing the electron-withdrawing capabilities generally leads to a lowering of the HOMO level with a consequent slight widening of the HOMO− LUMO gap and a blue shift in emission. The complexes reported exhibit high emission quantum yields and long luminescent lifetimes, typical of iridium(III) complexes, and most of them show reversible redox processes in solution. Also, many of the complexes reported here have been obtained as single crystals suitable for X-ray crystallography. Two of the complexes were further tested as phosphorescent dyes in OLED devices and showed high external quantum efficiencies (∼7%) and color points better than the "standard" for blue iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C 2′ ]picolinate (FIrpic). We also report the full electrochemical investigation of FIrpic in different solvents. Baldo, M. A.; O'Brien, D. F.; You, Y.; Shoustikov, A.; Sibley, S.; Thompson, M. E.; Forrest, S. R. Nature 1998, 395, 151-154. (6) Tsuboyama, A.; Iwawaki, H.; Furugori, M.; Mukaide, T.; Kamatani, J.; Igawa, S.; Moriyama, T.; Miura, S.; Takiguchi, T.; Okada, S.; Hoshino, M.; Ueno, K.
A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthes... more A palladium-catalyzed Stille coupling reaction was employed as a versatile method for the synthesis of a novel terpyridine-pincer (3, TPBr) bridging ligand, 4'-{4-BrC6H2(CH2NMe2)2-3,5}-2,2':6',2' '-terpyridine. Mononuclear species [PdX(TP)] (X = Br, Cl), [Ru(TPBr)(tpy)](PF6)2, and [Ru(TPBr)2](PF6)2, synthesized by selective metalation of the NCNBr-pincer moiety or complexation of the terpyridine of the bifunctional ligand TPBr, were used as building blocks for the preparation of heterodi- and trimetallic complexes [Ru(TPPdCl)(tpy)](PF6)2 (7) and [Ru(TPPdCl)2](PF6)2 (8). The molecular structures in the solid state of [PdBr(TP)] (4a) and [Ru(TPBr)2](PF6)2 (6) have been determined by single-crystal X-ray analysis. Electrochemical behavior and photophysical properties of the mono- and heterometallic complexes are described. All the above di- and trimetallic Ru complexes exhibit absorption bands attributable to (1)MLCT (Ru --> tpy) transitions. For the heteroleptic complexes, the transitions involving the unsubstituted tpy ligand are at a lower energy than the tpy moiety of the TPBr ligand. The absorption bands observed in the electronic spectra for TPBr and [PdCl(TP)] have been assigned with the aid of TD-DFT calculations. All complexes display weak emission both at room temperature and in a butyronitrile glass at 77 K. The considerable red shift of the emission maxima relative to the signal of the reference compound [Ru(tpy)2]2+ indicates stabilization of the luminescent 3MLCT state. For the mono- and heterometallic complexes, electrochemical and spectroscopic studies (electronic absorption and emission spectra and luminescence lifetimes recorded at room temperature and 77 K in nitrile solvents), together with the information gained from IR spectroelectrochemical studies of the dimetallic complex [Ru(TPPdSCN)(tpy)](PF6)2, are indicative of charge redistribution through the bridging ligand TPBr. The results are in line with a weak coupling between the {Ru(tpy)2} chromophoric unit and the (non)metalated NCN-pincer moiety.
The new fully planar cyclopentadithiophene, 4-n-dodecylidene-4H-cyclopenta(2,1-b;3,4-bA)dithiophe... more The new fully planar cyclopentadithiophene, 4-n-dodecylidene-4H-cyclopenta(2,1-b;3,4-bA)dithiophene, shows extensive p-stacking in the solid state with short intermolecular distances (ca. 3.5 Å) between adjacent molecules. Polymerisation of this monomer by two different protocols gave solution processable alkenyl-bridged cyclopentadithiophene polymers with extended p-conjugation in the main chain.
A number of strategies exist to design molecular materials based on self-assembled peptides and t... more A number of strategies exist to design molecular materials based on self-assembled peptides and their derivatives. These include soft materials based on a variety of structural motifs including coiled-coils, b-sheets, b-hairpins, and peptide amphiphiles. In these systems, the peptide chains usually contain at least ten amino acids. It has been known for some time that using aromatic components in conjunction with peptides allows the use of much smaller peptides by taking advantage of p-stacking interactions. One system that has been illustrated is that of N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF) which forms a hydrogel under physiological conditions. This example and other closely related aromatic short peptide derivatives are known to form fibrous hydrogels that have found applications in biological sensing and cell culture. Understanding of the supramolecular structures formed by these molecules will aid the rational design of new architectures tailored to the needs of specific biological and non-biological applications. However, to date a complete structure has not been proposed for any member of this class of self-assembly systems. Here we apply a number of spectroscopic techniques to Fmoc-FF and construct a model based on the data obtained comprising a new nanocylindrical molecular architecture based on p-p interlocked b-sheets. Transmission electron microscopy (TEM) and wide angle X-ray scattering (WAXS) was used to confirm the proposed model.
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Papers by Paolo Coppo