The application of calcined natural dolomitic rock as a solid base catalyst in triglyceride transesterification for biodiesel synthesis

Natural dolomitic rock has been investigated in the transesterification of C-4 and C-8 triglycerides and olive oil with a view to determining its viability as a solid base catalyst for use in biodiesel synthesis. XRD reveals that the dolomitic rock comprised 77% dolomite and 23% magnesian calcite. The generation of basic sites requires calcination at 900 degrees C, which increases the surface area and transforms the mineral into MgO nanocrystallites dispersed over CaO particles. Calcined dolomitic rock exhibits high activity towards the liquid phase transesterification of glyceryl tributyrate and trioctanoate, and even olive oil, with methanol for biodiesel production.

Recyclable copper catalysts based on imidazolium-tagged bis(oxazolines): A marked enhancement in rate and enantioselectivity for Diels-Alder reactions in ionic liquid

Imidazolium-tagged bis(oxazolines) have been prepared and used as chiral ligands in the copper(II)-catalysed Diels-Alder reaction of N-acryloyl- and N-crotonoyloxazolidinones with cyclopentadiene and 1,3-cyclohexadiene in the ionic liquid 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [emim][NTf2]. A significant and substantial enhancement in the rate and enantioselectivity was achieved in [emim][NTf2] compared with dichloromethane. For example, complete conversion and enantioselectivities up to 95 % were obtained for the reaction between N-acryloyloxazolidinone and cyclopentadiene within 2 min in [emim][NTf2] whereas the corresponding reaction in dichloromethane required 60 min to reach completion and gave an ee of only 16 %. The enhanced rates obtained in the ionic liquid enabled a catalyst loading as low as 0.5 mol % to give complete conversion within 2 min while retaining the same level of enantioselectivity. The imidazolium-tagged catalysts can be recycled ten times without any loss in activity or enantioselectivity and showed much higher affinity for the ionic liquid phase during the recycle procedure than the analogous uncharged ligand.

Ionic Liquid Effect on the Reversal of Configuration for the Magnesium(II) and Copper(II) Bis(oxazoline)-Catalysed Enantioselective Diels-Alder Reaction

Ionic liquids have been used to support a range of magnesium-and copper-based bis(oxazoline) complexes for the enantioselective Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene. Compared with reaction performed in dichloromethane or diethyl ether, an enhancement in ee is observed with a large increase in reaction rate. In addition, for non-sterically hindered bis(oxazoline) ligands, that is, phenyl functionalised ligands, a reversal in configuration is found in the ionic liquid, 1-ethyl-3-methylimidazolium bis[(trifluoromethanesulfonyl)imide], compared with molecular solvents. Supported ionic liquid phase catalysts have also been developed using surface-modified silica which show good reactivity and enantioselectivity for the case of the magnesium-based bis(oxazoline) complexes. Poor ees and conversion were observed for the analogous copper-based systems. Some drop in ee was found on supporting the catalyst due a drop in the rate of reaction and, therefore, an increase in the contribution from the uncatalysed a chiral reaction.

Synthesis of mesoporous tungsten carbide-supported platinum and its electrocatalytic activity for methanol oxidation

High activity and stability during oxidation of methanol under the relatively anode environment are two main evaluation criterias for an effective anode electrocatalyst in direct methanol fuel cell (DMFC). Mesoporous WC samples with hollow structure were prepared by gas-solid reaction at the atmosphere of CH(4)/H(2) by using airflow spray dried ammonium metatungstate (AMT). The platinum supported on this material by impregnation-vapor phase deoxidation method served as a less expensive electro anode catalyst. XRD and SEM results showed that Pt particles were well dispersed on the surface of WC. The results showed that the Pt/WC-PME exhibited an attractive catalytic activity, and methanol oxidation process in Pt/WC-PME is affected by liquid-phase mass transfer. The results also indicated that the oxidation can be improved by raising temperatures.

Lanthanide oxide nanotubes and nanorods: synthesis, processing, luminescence and catalytic properties

Esta tese relata estudos de síntese, caracterização da estrutura e das propriedades de fotoluminescência e aplicações de nanotubos e nanobastonetes de óxidos de lantanídeos em pontas para microscopia de força atómica, catálise heterogénea e compósitos de base polimérica. Há um interesse crescente em compreender como o confinamento quântico decorrente da redução do tamanho de partícula pode influenciar a eficiência da luminescência, a dinâmica dos estados excitados, a transferência de energia e os efeitos de termalização de nanoluminóforos. Em nanocristais dopados com lantanídeos (Ln3+), e apesar da localização dos estados 4f, ocorrem efeitos de confinamento quântico via interacção com os modos vibracionais da rede. Em particular, a termalização anómala, descrita para uma variedade de nanocristais dopados com Ln3+, tem sido atribuída à ausência de modos vibracionais de menor frequência. Este nanoconfinamento pode ter impacto na dinâmica da luminescência, bem como na transferência de energia mediada por modos vibracionais e processos de upconversion. Nesta tese, relata-se o estudo deste efeito em nanotubos de Gd2O3:Eu3+. A influência de parâmetros como a concentração de európio e as condições de calcinação também foi investigada. Algumas aplicações destes óxidos de lantanídeos também foram exploradas, nomeadamente a modificação de pontas usadas em microscopia de força atómica com nanobastonetes de Gd2O3:Eu3+, lograda através de dielectroforese, técnica que não degrada a emissão de luz (rendimento quântico 0.47). As pontas modificadas são estáveis sob condições de trabalho, podendo ser aplicadas, por exemplo, em microscopia óptica de varrimento de campo próximo (SNOM). A oxidação em fase líquida do etilbenzendo foi investigada usando como catalisador nanotubos de CeO2, em presença dos oxidantes hidroperóxido de t-butilo e H2O2, e do solvente acetonitrilo, e temperaturas entre 55 e 105 ºC. Nanobastonetes de Gd2O3:Eu3+ recobertos com sílica foram preparados pelo método sol-gel. Esta cobertura resultou num aumento, quer do rendimento quântico de emissão, de 0.51 para 0.86 (excitação a 255 nm), quer dos tempos de vida,de 1.43 para 1.80 ms (excitação a 394.4 nm). A superfície dos nanotubos cobertos com sílica foi modificada com o agente de acoplamento metacrilato de 3-(trimetoxissilil)propilo que permitiu a preparação de compósitos através da subsequente polimerização in-situ do estireno por técnicas de miniemulsão e solução. ABSTRACT: This thesis reports on the synthesis, characterisation of the structure and photoluminescence properties, and applications of nanotubes and nanorods of lanthanides oxides in atomic force microscopy tips, heterogeneous catalysis and polymer-base composites. There is a growing interest in understanding how size-dependent quantum confinement affects the photoluminescence efficiency, excited-state dynamics, energy-transfer and thermalisation phenomena in nanophosphors. For lanthanide (Ln3+)-doped nanocrystals, and despite the localisation of the 4f states, confinement effects are induced mostly via electron-phonon interactions. In particular, the anomalous thermalisation reported for a handful of Ln3+-doped nanocrystals has been rationalised by the absence of lowfrequency phonon modes. This nanoconfinement may further impact on the Ln3+ luminescence dynamics, such as phonon-assisted energy transfer or upconversion processes. Here, this effect is investigated in Gd2O3:Eu3+ nanotubes. The influence of parameters such as europium concentration and calcination procedure is also studied. Some applications of these lanthanides oxides have been explored, for instance the modification of atomic force microscopy tips with photoluminescent Gd2O3:Eu3+ nanorods, using dielectrophoresis, a technique which preserves the red emission of the nanorods (quantum yield 0.47). The modified tips are stable under working conditions and may find applications in scanning near-field optical microscopy. The liquid-phase oxidation of ethylbenzene over CeO2 nanotubes has been investigated, using tert-butyl-hydroperoxide and H2O2 as the oxidising agents, and acetonitrile as the solvent, in the range 55-105 ºC. Gd2O3:Eu3+ nanorods have been coated with silica via a sol-gel approach. The silica coating increases both, the Eu3+ absolute emission quantum yields from 0.51 to 0.86 (255 nm excitation), and decay times from 1.43 to 1.80 ms (394.4 nm excitation). The silica coating was modified with 3- (trimethoxysilyl) propyl methacrylate and, subsequently, composites have been prepared by in-situ radical polymerisation of styrene via miniemulsion and solution routes.

Synthesis, characterisation and benzylation activity of vanadia impregnated iron pillared montmorillonite

Iron pillared Montmorillonite has been synthesised and it is then wet impregnated with vanadia with different vanadia composition. These catalysts are characterised using conventional techniques such as XRD analysis,FTIR analysis and surface area and pore volume measurements. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2.6 dimethylpyridine and temperature programmed desorption of ammonia. Activity studies are done in the liquid phase. It has been concluded that Lewis acidic sites are responsible for the benzylation of toluene when the benzylating agent is benzyl chloride while Bronsted acidic sites are responsible when the reagent is benzyl alcohol.

Synthesis, characterization and benzylation activity of nanocrystalline chromia loaded sulfated titania prepared via sol–gel route

Chromia loaded sulfated titania has been synthesized via sol–gel route with different chromia loadings. These catalysts are characterized using conventional techniques such as XRD analysis, FTIR analysis, surface area and pore volume measurements, EDX, SEM and UV–Vis diffuse reflectance spectral analysis. Acidity is measured using spectrophotometric monitoring of adsorption of perylene, thermogravimetric desorption of 2,6-dimethylpyridine and temperature programmed desorption of ammonia. Activity studies are done in the liquid phase. It has been concluded that Lewis acid sites are responsible for the benzylation of arenes with benzyl chloride.

Synthesis, characterization and catalytic activity of Nd203 supported V205 catalysts

A series of rare-earth neodymia supported vanadium oxide catalysts with various V205 loadings ranging from 3 to 15 wt.% were prepared by the wet impregnation method using ammonium metavanadate as the vanadium precursor. The nature of vanadia species formed on the support surface is characterized hy a series of different physicochemical techniques like X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR). BET surface area, diffuse reflectance UV-vis spectroscopy (DR UV-vis), thermal analysis (TG-DTG/DTA) and SEM. The acidity of the prepared systems were verified by the stepwise temperature programmed desorprion of ammonia (NH3-TPD) and found that the total acidity gets increased with the percentage of vanadia loading. XRD and FT1R results shows the presence of surface dispersed vanadyl species at lower loadings and the formation of higher vanadate species as the percentage composition of vanadia is increased above 9 wt.%. The low surface area of the support. calcination temperature and the percentage of vanadia loading are found to influence the formation of higher vanadia species. The catalytic activity of the V205-Nd203 catalysts was probed in the liquid phase hydroxylation of phenol and the result show that the present catalysts are active at lower vanadia concentrations.

Concomitant polymorphism of an antiferromagnetically coupled dicopper(II,II) complex with single strand helical assembly: synthesis, structure, DSC, magnetic and heterogeneous catalytic studies

Two concomitant polymorphic coordination complexes (dark blue - I and black - II) with the formula (Cu2C44H60N4O4) have been synthesized and characterized crystallographically. Magnetic measurements show the presence of a strong antiferromagnetic interaction and the 2J value corresponds extremely well to the theoretically calculated one, indicating the fact that it follows nicely the magneto-structural relationship. Immobilization of the copper(II) complex I on a 2D-hexagonal mesoporous silica showed good catalytic efficiency in the liquid phase partial oxidation of olefins in the presence of TBHP as an oxidant. (C) 2009 Elsevier Ltd. All rights reserved.

Recoverable rhodium nanoparticles: Synthesis, characterization and catalytic performance in hydrogenation reactions

We here report the first magnetically recoverable Rh(0) nanoparticle-supported catalyst with extraordinary recovery and recycling properties. Magnetic separation has been suggested as a very promising technique to improve recovery of metal-based catalysts in liquid-phase batch reactions. The separation method is significantly simple, as it does not require filtration, decantation, centrifugation, or any other separation technique thereby, overcoming traditional time- and solvent-consuming procedures. Our new magnetically separable catalytic system, comprised of Rh nanoparticles immobilized on silica-coated magnetite nanoparticles, is highly active and could be reused for up to 20 times for hydrogenation of cyclohexene (180,000 mol/mol(Rh)) and benzene (11,550 mol/mol(Rh) under mild conditions. (c) 2007 Elsevier B. V. All fights reserved.

Liquid-gas phase transition in Bose-Einstein condensates with time evolution

We study the effects of a repulsive three-body interaction on a system of trapped ultracold atoms in a Bose-Einstein condensed state. The stationary solutions of the corresponding s-wave nonlinear Schrödinger equation suggest a scenario of first-order liquid-gas phase transition in the condensed state up to a critical strength of the effective three-body force. The time evolution of the condensate with feeding process and three-body recombination losses has a different characteristic pattern. Also, the decay time of the dense (liquid) phase is longer than expected due to strong oscillations of the mean-squared radius.

De Novo Design of secondary structures: Synthesis and conformational studies

Chemists have long sought to extrapolate the power of biological catalysis and recognition to synthetic systems. These efforts have focused largely on low molecular weight catalysts and receptors; however, biological systems themselves rely almost exclusively on polymers, proteins and RNA, to perform complex chemical functions. Proteins and RNA are unique in their ability to adopt compact, well-ordered conformations, and specific folding provides precise spatial orientation of the functional groups that comprise the “active site”. These features suggest that identification of new polymer backbones with discrete and predictable folding propensities (“foldamers”) will provide a basis for design of molecular machines with unique capabilities. The foldamer approach complements current efforts to design unnatural properties into polypeptides and polynucleotides. The aim of this thesis is the synthesis and conformational studies of new classes of foldamers, using a peptidomimetic approach. Moreover their attitude to be utilized as ionophores, catalysts, and nanobiomaterials were analyzed in solution and in the solid state. This thesis is divided in thematically chapters that are reported below. It begins with a very general introduction (page 4) which is useful, but not strictly necessary, to the expert reader. It is worth mentioning that paragraph I.3 (page 22) is the starting point of this work and paragraph I.5 (page 32) isrequired to better understand the results of chapters 4 and 5. In chapter 1 (page 39) is reported the synthesis and conformational analysis of a novel class of foldamers containing (S)-β3-homophenylglycine [(S)-β3-hPhg] and D- 4-carboxy-oxazolidin-2-one (D-Oxd) residues in alternate order is reported. The experimental conformational analysis performed in solution by IR, 1HNMR, and CD spectroscopy unambiguously proved that these oligomers fold into ordered structures with increasing sequence length. Theoretical calculations employing ab initio MO theory suggest a helix with 11-membered hydrogenbonded rings as the preferred secondary structure type. The novel structures enrich the field of peptidic foldamers and might be useful in the mimicry of native peptides. In chapter 2 cyclo-(L-Ala-D-Oxd)3 and cyclo-(L-Ala-DOxd) 4 were prepared in the liquid phase with good overall yields and were utilized for bivalent ions chelation (Ca2+, Mg2+, Cu2+, Zn2+ and Hg2+); their chelation skill was analyzed with ESI-MS, CD and 1HNMR techniques and the best results were obtained with cyclo-(L-Ala-D-Oxd)3 and Mg2+ or Ca2+. Chapter 3 describes an application of oligopeptides as catalysts for aldol reactions. Paragraph 3.1 concerns the use of prolinamides as catalysts of the cross aldol addition of hydroxyacetone to aromatic aldeydes, whereas paragraphs 3.2 and 3.3 are about the catalyzed aldol addition of acetone to isatins. By means of DFT and AIM calculations, the steric and stereoelectronic effects that control the enantioselectivity in the cross-aldol addition of acetone to isatin catalysed by L-proline have been studied, also in the presence of small quantities of water. In chapter 4 is reported the synthesis and the analysis of a new fiber-like material, obtained from the selfaggregation of the dipeptide Boc-L-Phe-D-Oxd-OBn, which spontaneously forms uniform fibers consisting of parallel infinite linear chains arising from singleintermolecular N-H···O=C hydrogen bonds. This is the absolute borderline case of a parallel β-sheet structure. Longer oligomers of the same series with general formula Boc-(L-Phe-D-Oxd)n-OBn (where n = 2-5), are described in chapter 5. Their properties in solution and in the solid state were analyzed, in correlation with their attitude to form intramolecular hydrogen bond. In chapter 6 is reported the synthesis of imidazolidin-2- one-4-carboxylate and (tetrahydro)-pyrimidin-2-one-5- carboxylate, via an efficient modification of the Hofmann rearrangement. The reaction affords the desired compounds from protected asparagine or glutamine in good to high yield, using PhI(OAc)2 as source of iodine(III).

Liquid crystalline oligofluorenes and their derivatives

Homo-oligofluorenes (OFn), polyfluorenes (PF2/6) and oligofluorenes with one fluorenenone group in the center (OFnK) were synthesized. They were used as model compounds to understand of the structure-property relationships of polyfluorenes and the origin of the green emission in the photoluminescence (after photooxidation of the PFs) and the electroluminescence (EL) spectra. The electronic, electrochemical properties, thermal behavior, supramolecular self-assembly, and photophysical properties of OFn, PF2/6 and OFnK were investigated. Oligofluorenes with 2-ethylhexyl side chain (OF2-OF7) from the dimer up to the heptamer were prepared by a series of stepwise transition metal mediated Suzuki and Yamamoto coupling reactions. Polyfluorene was synthesized by Yamamoto coupling of 2,7-dibromo-9,9-bis(2-ethylhexyl)fluorene. Oligofluorenes with one fluorenone group in the center (OF3K, OF5K, OF7K) were prepared by Suzuki coupling between the monoboronic fluorenyl monomer, dimer, trimer and 2, 7-dibromofluorenone. The electrochemical and electronic properties of homo-oligofluorenes (OFn) were systematically studied by several combined techniques such as cyclic voltammetry, differential pulse voltammetry, UV-vis absorption spectroscopy, steady and time-resolved fluorescence spectroscopy. It was found that the oligofluorenes behave like classical conjugated oligomers, i.e., with the increase of the chain-length, the corresponding oxidation potential, the absorption and emission maximum, ionization potential, electron affinity, band gap and the photoluminescence lifetime displayed a very good linear relation with the reciprocal number of the fluorene units (1/n). The extrapolation of these linear relations to infinite chain length predicted the electrochemical and electronic properties of the corresponding polyfluorenes. The thermal behavior, single-crystal structure and supramolecular packing, alignment properties, and molecular dynamics of the homo-oligofluorenes (OFn) up to the polymer were studied using techniques such as TGA, DSC, WAXS, POM and DS. The OFn from tetramer to heptamer show a smectic liquid crystalline phase with clearly defined isotropization temperature. The oligomers do show a glass transition which exhibits n-1 dependence and allows extrapolation to a hypothetical glass transition of the polymer at around 64 °C. A smectic packing and helix-like conformation for the oligofluorenes from tetramer to heptamer was supported by WAXS experiments, simulation, and single-crystal structure of some oligofluorene derivatives. Oligofluorenes were aligned more easily than the corresponding polymer, and the alignability increased with the molecular length from tetramer to heptamer. The molecular dynamics in a series of oligofluorenes up to the polymer was studied using dielectric spectroscopy. The photophysical properties of OFn and PF2/6 were investigated by the steady-state spectra (UV-vis absorption and fluorescence spectra) and time-resolved fluorescence spectra both in solution and thin film. The time-resolved fluorescence spectra of the oligofluorenes were measured by streak camera and gate detection technique. The lifetime of the oligofluorenes decreased with the extension of the chain-length. No green emission was observed in CW, prompt and delayed fluorescence for oligofluorenes in m-THF and film at RT and 77K. Phosphorescence was observed for oligofluorenes in frozen dilute m-THF solution at 77K and its lifetime increased with length of oligofluorenes. A linear relation was obtained for triplet energy and singlet energy as a function of the reciprocal degree of polymerization, and the singlet-triplet energy gap (S1-T1) was found to decrease with the increase of degree of polymerization. Oligofluorenes with one fluorenone unit at the center were used as model compounds to understand the origin of the low-energy (“green”) emission band in the photoluminescence and electroluminescence spectra of polyfluorenes. Their electrochemical properties were investigated by CV, and the ionization potential (Ip) and electron affinity (Ea) were calculated from the onset of oxidation and reduction of OFnK. The photophysical properties of OFnK were studied in dilute solution and thin film by steady-state spectra and time-resolved fluorescence spectra. A strong green emission accompanied with a weak blue emission were obtained in solution and only green emission was observed on film. The strong green emission of OFnK suggested that rapid energy transfer takes place from higher energy sites (fluorene segments) to lower energy sites (fluorenone unit) prior to the radiative decay of the excited species. The fluorescence spectra of OFnK also showed solvatochromism. Monoexponential decay behaviour was observed by time-resolved fluorescence measurements. In addition, the site-selective excitation and concentration dependence of the fluorescence spectra were investigated. The ratio of green and blue emission band intensities increases with the increase of the concentration. The observed strong concentration dependence of the green emission band in solution suggests that increased interchain interactions among the fluorenone-containing oligofluorene chain enhanced the emission from the fluorenone defects at higher concentration. On the other hand, the mono-exponential decay behaviour and power dependence were not influenced significantly by the concentration. We have ruled out the possibility that the green emission band originates from aggregates or excimer formation. Energy transfer was further investigated using a model system of a polyfluorene doped by OFnK. Förster-type energy transfer took place from PF2/6 to OFnK, and the energy transfer efficiency increased with increasing of the concentration of OFnK. Efficient funneling of excitation energy from the high-energy fluorene segments to the low-energy fluorenone defects results from energy migration by hopping of excitations along a single polymer chain until they are trapped on the fluorenone defects on that chain or transferred onto neighbouring chains by Förster-type interchain energy transfer process. These results imply that the red-shifted emission in polyfluorenes can originate from (usually undesirable) keto groups at the bridging carbon atoms-especially if the samples have been subject to photo- or electro-oxidation or if fluorenone units are present due to an improper purification of the monomers prior to polymerization.

Investigation of heterogeneous catalysts for the synthesis of fine chemicals

In order to match the more stringent environmental regulations, heterogenization of traditional homogeneous processes is one of the main challenges of the modern chemical industry. Great results have been achieved in the fields of petrochemicals and base chemicals, whereas in fine chemical industry most of the synthetic procedures are based on multistep processes catalyzed by homogeneous catalysts mainly used in stoichiometric amounts. In the fine chemicals manufacture not so much efforts have been devoted to the investigation of suitable solid catalysts for the development of greener processes, then this sector represent a very attractive field of research. In this context, the present work deals with the extensive investigation of the possibility to heterogenize existing processes, in particular two different classes of reactions have been studied: alkylation of aromatic and heteroaromatic compounds and selective oxidation of aromatic alcohols. Traditional solid acid catalysts, such as zeolites, clays and alumina have been tested in the gas phase alkylation of 1,2-methylendioxybenzene, core building block of many drugs, pesticides and fragrances. The observed reactivity were clarified through a deep FTIR investigation complemented by ab initio calculation. The same catalysts were tested in the gas phase isopropylation of thiophene with the aim of clearly attribute the role of the reaction parameters in the reaction proceeding and verify the possibility to enhance the selectivity of one of the two possible isomers. Finally various Au/CeO2 catalysts were tested in the synthesis of benzaldehyde and piperonal, two aldehydes largely employed in the manufacture of fine chemical products, through liquid phase oxidation of the corresponding alcohols in very mild conditions.

Bottom-up solution synthesis of structurally defined graphene nanoribbons

Graphene nanoribbons (GNRs), which are defined as nanometer-wide strips of graphene, are attracting an increasing attention as one on the most promising materials for future nanoelectronics. Unlike zero-bandgap graphene that cannot be switched off in transistors, GNRs possess open bandgaps that critically depend on their width and edge structures. GNRs were predominantly prepared through “top-down” methods such as “cutting” of graphene and “unzipping” of carbon nanotubes, but these methods cannot precisely control the structure of the resulting GNRs. In contrast, “bottom-up” chemical synthetic approach enables fabrication of structurally defined and uniform GNRs from tailor-made polyphenylene precursors. Nevertheless, width and length of the GNRs obtainable by this method were considerably limited. In this study, lateral as well as longitudinal extensions of the GNRs were achieved while preserving the high structural definition, based on the bottom-up solution synthesis. Initially, wider (~2 nm) GNRs were synthesized by using laterally expanded monomers through AA-type Yamamoto polymerization, which proved more efficient than the conventional A2B2-type Suzuki polymerization. The wider GNRs showed broad absorption profile extending to the near-infrared region with a low optical bandgap of 1.12 eV, which indicated a potential of such GNRs for the application in photovoltaic cells. Next, high longitudinal extension of narrow (~1 nm) GNRs over 600 nm was accomplished based on AB-type Diels–Alder polymerization, which provided corresponding polyphenylene precursors with the weight-average molecular weight of larger than 600,000 g/mol. Bulky alkyl chains densely installed on the peripheral positions of these GNRs enhanced their liquid-phase processability, which allowed their formation of highly ordered self-assembled monolayers. Furthermore, non-contact time-resolved terahertz spectroscopy measurements demonstrated high charge-carrier mobility within individual GNRs. Remarkably, lateral extension of the AB-type monomer enabled the fabrication of wider (~2 nm) and long (>100 nm) GNRs through the Diels–Alder polymerization. Such longitudinally extended and structurally well-defined GNRs are expected to allow the fabrication of single-ribbon transistors for the fundamental studies on the electronic properties of the GNRs as well as contribute to the development of future electronic devices.