Synthesis and properties of methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole

The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles.     

Poly(3,6-dimethoxy-thieno[3,2-b]thiophene): a possible alternative to poly(3,4-ethylenedioxythiophene)(PEDOT)

Electropolymerization of the title compound leads to a conjugated polymer with redox potential, band gap, optical transparency in the doped state and stability similar to those of PEDOT.     

DFT and TD-DFT calculations on thieno[2,3-b]indole-based compounds for application in organic bulk heterojunction (BHJ) solar cells

Research on Chemical Intermediates - Eight novel organic compounds with donor–π–acceptor (D–π–A) structure were designed for use as donors in organic bulk...     

New push-pull systems based on indolo[3,2-b]carbazole and 1,2,4,5-tetrazine: synthesis,photophysical, and charge transport properties

5,11-Dihydroindolo[3,2-b]carbazoles were for the first time modified with acceptor 1,2,4,5-tetrazine fragments. The photophysical and charge-transport properties of the synthesized donor-acceptor heterocyclic systems were studied. It was shown that the introduction of the 1,2,4,5-tetrazine moieties makes it possible to increase the hole and electron mobility by one and two orders of magnitude, respectively, as compared to analogous 5,11-dihydroindolo-[3,2-b]carbazole derivatives studied previously.

     

Synthesis and optoelectronic properties of a novel dinuclear cyclometalated platinum(II) complex containing triphenylamine-substituted indolo[3,2-b]carbazole derivative in the single-emissive-layer WPLEDs

A novel bi-picolinic acid derivative of H₂dipic-BTICz containing binary triphenylamine-substituted indolo[3,2-b]carbazole (BTICz) unit and its dinuclear platinum(II) complex of (dfppy)₂Pt₂(dipic-BTICz) were synthesized as a single-component emitter used in the white polymer light-emitting diodes (WPLEDs), where dfppy is 2-(2,4-difluorophenyl)pyridine and dipic-BTICz is an anion of H₂dipic-BTICz. The photophysical and electrochemical properties of (dfppy)₂Pt₂(dipic-BTICz) were investigated. Compared with the reported mononuclear platinum complex of (dfppy)Pt(pic), (dfppy)₂Pt₂(dipic-BTICz) exhibited a red-shifted photoluminescent peak at 434 nm in dilute dichloromethane (10⁻⁵ M), but a weakened and red-shifted aggregation emission peak at 640 nm besides its intrinsic emission at 445 nm in its neat films. Stable pure white emissions with CIE coordinates of (0.325±0.005, 0.345±0.015) and a maximum brightness of 208 cd/m² were observed in the (dfppy)₂Pt₂(dipic-BTICz)-doped single-emissive-layer (SEL) PLEDs using a blend of poly(vinylcarbazole) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as a host matrix at 1 wt % dopant concentrations under applied voltages from 9 to 14 V. It indicates that the intrinsic and aggregation emissions of this dinuclear platinum complex were effectively tuned by inserting a new BTICz fluorophore in the dual picolinic acid derivative. Therefore, it is a promising single-component emitter to get white emission in SEL PLEDs.     

X-ray scattering study of thin films of poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene)

Poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT, is a semiconducting polymer that forms thin film transistors (TFTs) with high field effect mobility on silicon dioxide dielectrics that are treated with alkyltrichlorosilanes ( approximately 0.2 to 0.5 cm2/V s) but forms TFTs with poor mobility on bare silicon dioxide (<0.005 cm2/V s). The microstructure of spin-coated thin films of PBTTT on these surfaces was studied using synchrotron X-ray diffraction and atomic force microscopy. PBTTT crystallizes with lamellae of pi-stacked polymer chains on both surfaces. The crystalline domains are well-oriented relative to the substrate in the as-spun state and become highly oriented and more ordered with thermal annealing in the liquid crystalline mesophase. Although the X-ray scattering from PBTTT is nearly identical on both surfaces, atomic force microscopy showed that the domain size of the crystalline regions depends on the substrate surface. These results suggest that electrical transport in PBTTT films is strongly affected by the domain size of the crystalline regions and the disordered regions between them.     

Synthesis and properties of hole-transporting indolo[3,2-b]carbazole-based hydrazones with reactive functional groups

The synthesis of indolo[3,2-b]carbazole-based mono- and dihydrazones with reactive vinylbenzyl or vinyloxyethyl functional groups at the nitrogen atom of hydrazine moiety is reported. The thermal, optical, photophysical, electrochemical and photoelectrical properties of the synthesized compounds are described. They exhibit moderate thermal stability with 5% weight loss temperatures ranging from 273 to 343 °C. Self-polymerization of the monomers with vinylbenzyl functional groups starts at around 180 °C. The values of ionization potentials of the compounds measured by cyclic voltammetry are in the range of 4.94–5.00 eV and those estimated by electron photoemission in air range from 4.99 to 5.21 eV. Electron affinities range from −2.28 to −2.23 eV. The molecular structure of these hydrazones allows stable amorphous films to be prepared and the hole drift mobilities of the films exceed 10⁻³ cm²/V s at high electric fields.     

High molecular weight broad band-gap polymers based on indolo[3,2-b]carbazole and thiazolo[5,4-d]thiazole derivatives for solar cells

Two broad band-gap high molecular weight polymers, poly[(5,11-di(9’-heptadecanyl)-indolo[3,2-b]carbazole-alt-2,5-bis(3-n-octylthiophene-2-yl)-thiazolo[5,4-d]thiazole (PICzOTzTz) and poly[(5,11-di(9’-heptadecanyl)-indolo[3,2-b]carbazole-alt-2,5-bis(3-n-n-dodecylthiophene-2-yl)-thiazolo[5,4-d]thiazole]) (PICzDOTzTz), consisting of indolo[3,2-b]carbazole (ICz) and thiazolo[5,4-d]thiazole (TzTz) derivatives were synthesized by Suzuki polycondensation. Their physical, electrochemical and optical properties were characterized in details. The thermogravimetric analysis displayed high thermal stability, and 5% degradation temperatures of PICzOTzTz and PICzDOTzTz were 427 and 435°C, respectively. The optical band gaps of PICzOTzTz and PICzDOTzTz were 2.13 and 2.07 eV, respectively. The hole mobilities of PICzOTzTz and PICzDOTzTz were investigated by the space charge limited current (SCLC) method, which gave the mobility values of 7.21 × 10^–5 and 1.57 × 10^–4 cm²/(V s) for each polymer, respectively. Through the photo-voltaic characterization in polymer solar cells, they showed that the power conversion efficiencies of PICzOTzTz and PICzDOTzTz were 0.64 and 0.99%, respectively.     

Cu(I) substitutions. furo[3,2-b] pyridines,furo[3,2-c] pyridines and 1h-thieno[3,4-b] 2-pyran-l-ones from cuprous acetylides

The reaction of cuprous acetylides with aryl halides bearing a nucleophilic ortho substituent provides a versatile route to heterocyclic substances. The present work portrays the ease with which polyheterosystems can be constructed with this reaction. The synthesis of 2-substituted 7-iodofuro[3,2-c]pyridines, 2-substituted furo[3,2-b]pyridines, and 3-substituted lH-thieno-[3,4-b]-2-pyran-l-ones (thiaisocoumarins) is described. The latter two ring systems have not been previously reported.     

Synthesis,photophysical and electrochemical properties of novel 6,12-di(thiophen-2-yl) substituted indolo[3,2-b]carbazoles

Novel 5,11-dialkyl-6,12-di(thiophen-2-yl) substituted 5,11-dihydroindolo[3,2-b]carbazoles have been obtained and plausible ways for their further modifications via the Friedel–Crafts reaction are presented. The formylation of these indolo[3,2-b]carbazoles with dichloromethyl alkyl esters catalysed by Lewis acids leads to the formation of the corresponding 2,8-diformyl derivatives. Applicability of this formylation method for modification of indolo[3,2-b]carbazoles bearing electron-rich aromatic substituents at C-6 and C-12 has also been demonstrated. The Knoevenagel condensation of 2,8-dialdehydes with active methylene nitriles has been studied. The measurements of optical and redox properties for a number of new indolo[3,2-b]carbazoles have been performed.     

Furopyridines. XV . Synthesis and properties of ethyl 2-(3-furo[2,3-b]-, -[3,2-b]-, -[2,3-c]- and -[3,2-c]pyridyl)acetate

Ethyl 2-(3-furopyridyl)acetates 10a-d were synthesized from furopyridin-3(2H)-ones 4a-d by the Wittig-Horner reaction with diethyl cyanomethylphosphonate, hydrolysis and the subsequent esterification. Reaction of compounds 10a-d with lithium diisopropylamide (IDA) gave the corresponding methylene-lithiated intermediate, and the subsequent reaction with benzaldehyde, acetone and iodomethane afforded the methylene-alkylated product respectively, while N,N-dimethylacetamide did not give any reaction product. The 2-position of 10a, b and d is alkylated by the lithiation with excess of LDA and the successive reaction with an electrophile.     

Three-dimensional packing structure and electronic properties of biaxially oriented poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) films

We use a systematic approach that combines experimental X-ray diffraction (XRD) and computational modeling based on molecular mechanics and two-dimensional XRD simulations to develop a detailed model of the molecular-scale packing structure of poly(2,5-bis (3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT-C(14)) films. Both uniaxially and biaxially aligned films are used in this comparison and lead to an improved understanding of the molecular-scale orientation and crystal structure. We then examine how individual polymer components (i.e., conjugated backbone and alkyl side chains) contribute to the complete diffraction pattern, and how modest changes to a particular component orientation (e.g., backbone or side-chain tilt) influence the diffraction pattern. The effects on the polymer crystal structure of varying the alkyl side-chain length from C(12) to C(14) and C(16) are also studied. The accurate determination of the three-dimensional polymer structure allows us to examine the PBTTT electronic band structure and intermolecular electronic couplings (transfer integrals) as a function of alkyl side-chain length. This combination of theoretical and experimental techniques proves to be an important tool to help establish the relationship between the structural and electronic properties of polymer thin films.     

Synthesis and optoelectronic properties of transition metal complexes incorporating dithieno[3,2-b:2',3'-d]phosphole ligands

A series of dithieno[3,2-b:2',3'-d]phosphole-based transition metal complexes, including Au, Fe, Pt, Rh and W as central metals have been synthesised and characterised. Structural investigations by X-ray single crystal crystallography supported the high degree of pi-conjugation in the dithienophosphole ligands. This essential requirement for potential applications in molecular electronics and optoelectronics provides small band gaps for the materials. Investigations toward the optoelectronic properties of the respective complexes by fluorescence spectroscopy indicated that systematic alterations of the electronic structure are connected to different variables such as transition metal employed, functionalisation of the dithienophosphole ligands as well as complex geometries. The investigated Pt-based complexes exhibit only poor photoluminescence whereas Rh-, W- and Fe-based species with silyl functionalised dithienophosphole ligands show appreciable photophysical properties. The Au complexes investigated exhibit strong photoluminescence properties with very intriguing features in terms of excitation and emission wavelengths, intensity as well as selectivity.     

Recent progress on the chemistry of thieno[3,2-b]quinoline derivatives (part III)

This review describes the methods of preparation and the chemical reactivity of thieno[3,2-b]quinolines.     

Conjugation of organoruthenium(II) 3-(1H-benzimidazol-2-yl)pyrazolo[3,4-b]pyridines and indolo[3,2-d]benzazepines to recombinant human serum albumin: a strategy to enhance cytotoxicity in cancer cells

Following our strategy of coupling cyclin-dependent kinase (Cdk) inhibitors with organometallic moieties to improve their physicochemical properties and bioavailability, five organoruthenium complexes (1c-5c) of the general formula [RuCl(η(6)-arene)(L)]Cl have been synthesized in which the arene is 4-formylphenoxyacetyl-η(6)-benzylamide and L is a Cdk inhibitor [3-(1H-benzimidazol-2-yl)-1H-pyrazolo[3,4-b]pyridines (L1-L3) and indolo[3,2-d]benzazepines (L4 and L5)]. All of the compounds were characterized by spectroscopic and analytical methods. Upon prolonged standing (2-3 months) at room temperature, the dimethyl sulfoxide (DMSO) solutions of 1c and 2c(-HCl) afforded residues, which after recrystallization from EtOH and EtOH/H(2)O, respectively, were shown by X-ray diffraction to be cis,cis-[Ru(II)Cl(2)(DMSO)(2)(L1)]·H(2)O and mer-[Ru(II)Cl(DMSO)(3)(L2-H)]·H(2)O. Compound 5c, with a coordinated amidine unit, undergoes E/Z isomerization in solution. The antiproliferative activities and effects on the cell cycle of the new compounds were evaluated. Complexes 1c-5c are moderately cytotoxic to cancer cells (CH1, SW480, A549, A2780, and A2780cisR cell lines). Therefore, in order to improve their antiproliferative effects, as well as their drug targeting and delivery to cancer cells, 1c-5c were conjugated to recombinant human serum albumin, potentially exploiting the so-called "enhanced permeability and retention" effect that results in the accumulation of macromolecules in tumors. Notably, a marked increase in cytotoxicity of the albumin conjugates was observed in all cases.     

2-[3-(Trifluoromethyl)phenyl]furo[3,2-b]pyrroles: synthesis and reactions

The synthesis and reactions of methyl 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole-5-carboxylate (1a) are described. Upon reaction with methyl iodide, benzyl chloride, or acetic anhydride, this compound gave N-substituted products 1b-d. By hydrolysis of compounds 1a-c, the corresponding acids 2a-c were formed, or by reaction with hydrazine-hydrate, the corresponding carbohydrazides 3a-c were formed. By heating 2-[3-(trifluoromethyl)phenly]-4H-furo[3,2-b]pyrrole-5-carboxylic acid (2a) in acetic anhydride, 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-b]pyrrole (4) was formed. By hydrolysis of 4, 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole (5a) was formed, and reactions with methyl iodide or benzyl chloride gave N-substituted products 5b-c. The reaction of 4 with dimethyl butynedioate gave substituted benzo[b]furan 6. Compound 3a reacted with triethyl orthoesters giving 7a-c, which afforded with phosphorus (V) sulphide the corresponding thiones 8a-c. The thiones 8a-c reacted with hydrazine hydrate to form hydrazine derivatives 9a-c. The reaction of triethyl orthoformiate with compounds 9a-c led to furo[2′,3′: 4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 10a-c. Hydrazones 11a-c were formed from 3a-c and 5-[3-(trifluoromethyl)phenyl]furan-2-carboxaldehyde. The effect of microwave irradiation on some condensation reactions was compared with “classical” conditions. The results showed that microwave irradiation shortens the reaction time while affording comparable yields.     

Synthesis and antitumor activity of 7-(N-glycosylamino)-indolo[3,2-b]quinolines

Novel indolo[3,2-b]quinolines (1d-g), introduced at the 7-position with an N-glycosylamino group, were prepared and their antitumor activities against leukemia P388 in mice were examined. The N-Galactopyranosylamino derivative (1e) was a much more potent anti-leukemia compound (optimal dose = 25 mg/kg, T/C greater than 333%, cure 5/6) than lead compound 1a.     

Synthesis of benzofuro[3,2-b] quinolin-6(11H) one and derivatives

A new and efficient synthesis of benzof'uro[3,2-b]quinolin-6(11H) one ( 3 ) is reported, by treatment of 2- {[(phenoxy)acetyl]amino} benzoic acid ( 6a ) with polyphosphoric acid. An intermediate in the conversion of 3 to 6a , namely, 2-(3-benzofuranylamino)benzoic acid ( 7 ), was defined. An improved method for the synthesis of 6a is also described, which was used to prepare analogs ( 6b-n ) of 6a . In addition, an 11-alkoxy derivative ( 8 ) and 11-dialkylamino derivatives ( 10 and 11 ) of benzofuro [3,2-b]quinoline were prepared from 3 .