A Novel Spiro[acridine‐9,9′‐fluorene] Derivatives Containing Phenanthroimidazole Moiety for Deep‐Blue OLED Application

Typical π–π stacking and aggregation‐caused quenching could be suppressed in the film‐state by the spiro conformation molecular design in the field of organic light‐emitting diodes (OLEDs). Herein, a novel deep‐blue fluorescent material with spiro conformation, 1‐(4‐(tert ‐butyl)phenyl)‐2‐(4‐(10‐phenyl‐10H ‐spiro[acridine‐9,9′‐fluoren]‐2‐yl)phenyl)‐1H ‐phenanthro[9,10‐d ]imidazole ( SAF‐BPI ), was designed and synthesized. The compound consists of spiro‐acridine‐fluorene (SAF) as donor part and phenanthroimidazole (BPI) as acceptor part. Owing to the rigid SAF skeleton, this compound exhibits a high thermal stability with a glass transition temperature (T _g) of 198 °C. The compound exhibits bipolar transporting characteristics demonstrated by the single‐carrier devices. The non‐doped OLEDs based on the SAF‐BPI as the emitting layer shows maximum emission at 448 nm, maximum luminance of 2122 cd m⁻², maximum current efficiency (CE) of 3.97 cd A⁻¹, and a maximum power efficiency of 2.08 lm W⁻¹. The chromaticity coordinate is stable at (0.15, 0.10) at the voltage of 7–11 V. The device shows a slow efficiency roll‐off with CE of 3.35 and 2.85 cd A⁻¹ at 100 and 1000 cd m⁻², respectively.     

A Novel trans‐1‐(9‐Anthryl)‐2‐phenylethene Derivative Containing a Phenanthroimidazole Unit for Application in Organic Light‐Emitting Diodes

Aryl‐substituted phenanthroimidazoles (PIs) have attracted tremendous attention in the field of organic light‐emitting diodes (OLEDs), because they are simple to synthesize and have excellent thermal properties, high photoluminescence quantum yields (PLQYs), and bipolar properties. Herein, a novel blue–green emitting material, (E)‐2‐{4′‐[2‐(anthracen‐9‐yl)vinyl]‐[1,1′‐biphenyl]‐4‐yl}‐1‐phenyl‐1H‐phenanthro[9,10‐d]imidazole (APE‐PPI), containing a t‐APE [1‐(9‐anthryl)‐2‐phenylethene] core and a PI moiety was designed and synthesized. Owing to the PI skeleton, APE‐PPI possesses high thermal stability and a high PLQY, and the compound exhibits bipolar transporting characteristics, which were identified by single‐carrier devices. Nondoped blue–green OLEDs with APE‐PPI as the emitting layer show emission at λ=508 nm, a full width at half maximum of 82 nm, a maximum brightness of 9042 cd m^?2, a maximum current efficiency of 2.14 cd A^?1, and Commission Internationale de L'Eclairage (CIE) coordinates of (0.26, 0.55). Furthermore, a white OLED (WOLED) was fabricated by employing APE‐PPI as the blue–green emitting layer and 4‐(dicyanomethylene)‐2‐tert‐butyl‐6‐(1,1,7,7‐tetramethyljulolidin‐4‐yl‐vinyl)‐4H‐pyran (DCJTB) doped in tris‐(8‐hydroxyquinolinato)aluminum (Alq₃) as the red–green emitting layer. This WOLED exhibited a maximum brightness of 10029 cd m^?2, a maximum current efficiency of 16.05 cd A^?1, CIE coordinates of (0.47, 0.47), and a color rendering index (CRI) of 85. The high performance of APE‐PPI‐based devices suggests that the t‐APE and PI combination can potentially be used to synthesize efficient electroluminescent materials for WOLEDs.     

Alcohol‐Soluble Electron‐Transport Materials for Fully Solution‐Processed Green PhOLEDs

Two alcohol‐soluble electron‐transport materials (ETMs), diphenyl(4‐(1‐phenyl‐1H‐benzo[d]imidazol‐2‐yl)phenyl)phosphine oxide (pPBIPO) and (3,5‐bis(1‐phenyl‐1H‐benzo[d]imidazol‐2‐yl)phenyl)diphenylphosphine oxide (mBPBIPO), have been synthesized. The physical properties of these ETMs were investigated and they both exhibited high electron‐transport mobilities (1.67×10^?4 and 2.15×10^?4 cm² V^?1 s^?1), high glass‐transition temperatures (81 and 110 °C), and low LUMO energy levels (?2.87 and ?2.82 eV, respectively). The solubility of PBIPO in n‐butyl alcohol was more than 20 mg mL^?1, which meets the requirement for fully solution‐processed organic light‐emitting diodes (OLEDs). Fully solution‐processed green‐phosphorescent OLEDs were fabricated by using alcohol‐soluble PBIPO as electron‐transport layers (ETLs), and they exhibited high current efficiencies, power efficiencies, and external quantum efficiencies of up to 38.43 cd A^?1, 26.64 lm W^?1, and 10.87 %, respectively. Compared with devices that did not contain PBIPO as an ETM, the performance of these devices was much improved, which indicated the excellent electron‐transport properties of PBIPO.     

Phosphorescent Cyclometalated Iridium(III) Complexes That Contain Substituted 2‐Acetylbenzo[b]thiophen‐3‐olate Ligand for Red Organic Light‐Emitting Devices

We report the synthesis of a new class of thermally stable and strongly luminescent cyclometalated iridium(III) complexes 1 – 6 , which contain the 2‐acetylbenzo[b]thiophene‐3‐olate (bt) ligand, and their application in organic light‐emitting diodes (OLEDs). These heteroleptic iridium(III) complexes with bt as the ancillary ligand have a decomposition temperature that is 10–20 % higher and lower emission self‐quenching constants than those of their corresponding complexes with acetylacetonate (acac). The luminescent color of these iridium(III) complexes could be fine‐tuned from orange (e.g., 2‐phenyl‐6‐(trifluoromethyl)benzo[d]thiazole (cf₃bta) for 4 ) to pure red (e.g., lpt (Hlpt=4‐methyl‐2‐(thiophen‐2‐yl)quinolone) for 6 ) by varying the cyclometalating ligands (C‐deprotonated C^N). In particular, highly efficient OLEDs based on 6 as dopant (emitter) and 1,3‐bis(carbazol‐9‐yl)benzene (mCP) as host that exhibit stable red emission over a wide range of brightness with CIE chromaticity coordinates of (0.67, 0.33) well matched to the National Television System Committee (NTSC) standard have been fabricated along with an external quantum efficiency (EQE) and current efficiency of 9 % and 10 cd A^?1, respectively. A further 50 % increase in EQE (>13 %) by replacing mCP with bis[4‐(6H‐indolo[2,3‐b]quinoxalin‐6‐yl)phenyl]diphenylsilane (BIQS) as host for 6 in the red OLED is demonstrated. The performance of OLEDs fabricated with 6 (i.e., [(lpt)₂Ir(bt)]) was comparable to that of the analogous iridium(III) complex that bore acac (i.e., [(lpt)₂Ir(acac)]; 6 a in this work) [Adv. Mater.­ 2011 , 23, 2981] fabricated under similar conditions. By using ntt (Hnnt=3‐hydroxynaphtho[2,3‐b]thiophen‐2‐yl)(thiophen‐2‐yl)methanone) ligand, a substituted derivative of bt, the [(cf₃bta)₂Ir(ntt)] was prepared and found to display deep red emission at around 700 nm with a quantum yield of 12 % in mCP thin film.     

Deep Red to Near‐Infrared Emitting Rhenium(I) Complexes: Synthesis,Characterization, Electrochemistry,Photophysics, and Electroluminescence Studies

A series of triarylamine‐containing tricarbonyl rhenium(I) complexes, [BrRe(CO)₃(N^N)] (N^N=5,5′‐bis(N,N‐diaryl‐4‐[ethen‐1‐yl]‐aniline)‐2,2′‐bipyridine), has been designed and synthesized by introducing a rhenium(I) metal center into a donor‐π‐acceptor‐π‐donor structure. All of the complexes showed an intense broad structureless emission band in dichloromethane at around 680–708 nm, which originated from an excited state of intraligand charge transfer (³ILCT) character from the triarylamine to the bipyridine moiety. Upon introduction of the bulky and electron‐donating pentaphenylbenzene units attached to the aniline groups, the emission bands were found to be red shifted. The nanosecond transient absorption spectra of two selected complexes were studied, which were suggestive of the formation of an initial charge‐separated state. Computational studies have been performed to provide further insight into the origin of the absorption and emission. One of the rhenium(I) complexes has been utilized in the fabrication of organic light‐emitting diodes (OLEDs), representing the first example of the realization of deep red to near‐infrared rhenium(I)‐based OLEDs with an emission extending up to 800 nm.     

Adamantane‐Substituted Acridine Donor for Blue Dual Fluorescence and Efficient Organic Light‐Emitting Diodes

To date, blue dual fluorescence emission (DFE) has not been realized because of the limited choice of chemical moieties and severe geometric deformation of the DFE emitters leading to strong intramolecular charge transfer (ICT) with a large Stokes shift in excited states. Herein, an emitter (1′r,5′R,7′S)‐10‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)phenyl)‐10H‐spiro [acridine‐9,2′‐adamantane] (a‐DMAc‐TRZ) containing a novel adamantane‐substituted acridine donor is reported, which exhibits unusual blue DFE. The introduction of the rigid and bulky adamantane moiety not only suppressed the geometry relaxation in excited state, but also induced the formation of quasi‐axial conformer (QAC) and quasi‐equatorial conformer (QEC) geometries, leading to deep‐blue conventional fluorescence and sky‐blue thermally activated delayed fluorescence (TADF). The resulting organic light‐emitting diodes (OLEDs) achieved a maximum external quantum efficiency (EQE) of about 29 %, which is the highest reported for OLEDs based on dual‐conformation emitters.     

Synthesis,one‐ and two‐photon properties of poly[9,10‐bis(3,4‐bis(2‐ethylhexyl‐oxy)phenyl)‐2,6‐anthracenevinylene‐alt‐N‐octyl‐3,6‐/2,7‐carbazolevinylene]

The synthesis, one‐ and two‐photon absorption (TPA) and emission properties of two novel 2,6‐anthracenevinylene‐based copolymers, poly[9,10‐bis(3,4‐bis(2‐ethylhexyloxy)phenyl)‐2,6‐anthracenevinylene‐alt‐N‐octyl‐3,6‐carbazolevinyl‐ene] ( P1 ) and poly[9,10‐bis(3,4‐bis(2‐ethylhexyloxy)phenyl)‐2,6‐anthracenevinyl‐ene‐alt‐N‐octyl‐2,7‐carbazolevinylene] ( P2 ) were reported. The as‐synthesized polymers have the number‐average molecular weights of 1.56 × 10⁴ for P1 and 1.85 × 10⁴ g mol^?1 for P2 and are readily soluble in common organic solvents. They emit strong bluish‐green one‐ and two‐photon excitation fluorescence in dilute toluene solution (? _P1 = 0.85, ? _P2 = 0.78, λ_em( P1 ) = 491 nm, λ_em( P2 ) = 483 nm). The maximal TPA cross‐sections of P1 and P2 measured by the two‐photon‐induced fluorescence method using femtosecond laser pulses in toluene are 840 and 490 GM per repeating unit, respectively, which are obviously larger than that (210 GM) of poly[9,10‐bis‐(3,4‐bis(2‐ethylhexyloxy) phenyl)‐2,6‐anthracenevinylene], indicating that the poly(2,6‐anthracenevinylene) derivatives with large TPA cross‐sections can be obtained by inserting electron‐donating moieties into the polymer backbone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 463–470, 2010     

The crystal structure,luminescence and nitrobenzene‐sensing properties of a two‐dimensional MnII coordination polymer based on 2,6‐bis(imidazol‐1‐yl)pyridine

A two‐dimensional Mn^II coordination polymer (CP), poly[bis[μ₂‐2,6‐bis(imidazol‐1‐yl)pyridine‐κ²N³:N^3′]bis(thiocyanato‐κN)manganese] [Mn(NCS)₂(C₁₁H₉N₅)₂]_n, (I), has been obtained by the self‐assembly reaction of Mn(ClO₄)₂·6H₂O, NH₄SCN and bent 2,6‐bis(imidazol‐1‐yl)pyridine (2,6‐bip). CP (I) was characterized by FT–IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. The crystal structure features a unique two‐dimensional (4,4) network with one‐dimensional channels. The luminescence and nitrobenzene‐sensing properties were explored in a DMF suspension, revealing that CP (I) shows a strong luminescence emission and is highly sensitive for nitrobenzene detection.     

Molecular Design of Thermally Activated Delayed‐Fluorescent Emitters Using 2,2′‐Bipyrimidine as the Acceptor in Donor–Acceptor Structures

Donor–acceptor–donor (D–A–D)‐type thermally activated delayed fluorescence (TADF) emitters 5,5′‐bis{4‐[9,9‐dimethylacridin‐10(9H )‐yl]phenyl}‐2,2′‐bipyrimidine (Ac‐bpm) and 5,5′‐bis[4‐(10H ‐phenoxazin‐10‐yl)phenyl]‐2,2′‐bipyrimidine (Px‐bpm), based on the 2,2′‐bipyrimidine accepting unit, were developed and their TADF devices were fabricated. The orthogonal geometry between the donor unit and the 2,2′‐bipyrimidine accepting core facilitated a HOMO/LUMO spatial separation, thus realizing thermally activated delayed fluorescence. The exhibited electroluminescence ranged from green to yellow, depending on the donor unit, with maximum external quantum efficiencies of up to 17.1 %.     

Palladium‐Catalyzed Annulation of 9‐Halophenanthrenes with Alkynes: Synthesis,Structural Analysis,and Properties of Acephenanthrylene‐Based Derivatives

The palladium‐catalyzed annulation of 9‐bromo‐ and 9‐chlorophenanthrenes with alkynes gave 4,5‐disubstituted acephenanthrylenes in yields of 58–95 % (9 examples). Asymmetric alkynes, such as 1‐phenyl‐1‐propyne, 1‐phenyl‐1‐hexyne, and 1‐cyclopropyl‐2‐phenylethyne, regioselectively form (cyclo)alkyl‐substituted products, following the regular rule that governs the carbopalladation of alkynes. This synthetic protocol can also be utilized in annulations with several π‐extended bromoarenes, such as 7‐bromo[5]helicene, 5‐bromo[4]helicene, 9‐bromoanthracene, 3‐bromoperylene, and 3‐bromofluoranthene, to give the corresponding annulated products in moderate to good yields (51–86 %; 6 examples). Similarly, bromocorannulene produced highly curved 1,2‐disubstituted cyclopentacorannulenes. Reactions of 6,12‐dibromochrysene and 4,7‐dibromo[4]helicene with di(4‐tolyl)ethyne provided the twofold annulated products in moderate yields. 4,5‐Diphenylacephenanthrylene and 6,7‐diphenylbenzo[a]acephenanthrylene thus generated were converted into phenanthro[9,10‐e]acephenanthrylene and benzo[a]phenanthro[9,10‐e]acephenanthrylene, respectively, by oxidative cyclodehydrogenation. The structures of 4,5‐diphenylacephenanthrylene, 4,5‐diphenyldibenzo[a,l]acephenanthrylene, 1,2‐diarylcyclopentacorannulenes, and benzo[a]phenanthro[9,10‐e]acephenanthrylene were verified by X‐ray crystallography. The photophysical and electrochemical properties of the selected annulated products were investigated.     

18‐Crown‐6 Catalyzed Microwave‐mediated Synthesis of Symmetric Bis‐Heterocyclic Compounds under Solvent‐free Condition

An efficient, solvent‐free and 18‐crown‐6 catalyzed method for the synthesis of N‐alkyl‐4‐(4‐(5‐(2‐(alkyl‐amino)thiazol‐4‐yl)pyridin‐3‐yl)phenyl)thiazol‐2‐amine, N‐alkyl‐4‐(5‐(2‐alkyamino)thiazol‐4‐yl)pyridine‐3‐yl)thiazol‐2‐amine, and 4,4′‐bis‐{2‐[amino]‐4‐thiazolyl}biphenyl bis‐heterocyclic derivatives via microwave accelerated cyclization is presented.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

A three‐dimensional ZnII coordination polymer constructed from 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands exhibiting photoluminescence

Ligands based on polycarboxylic acids are excellent building blocks for the construction of coordination polymers; they may bind to a variety of metal ions and form clusters, as well as extended chain or network structures. Among these building blocks, biphenyltetracarboxylic acids (H₄bpta) with C ₂ symmetry have recently attracted attention because of their variable bridging and multidentate chelating modes. The new luminescent three‐dimensional coordination polymer poly[(μ₅‐1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylato)bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]dizinc(II)], [Zn₂(C₁₆H₆O₈)(C₁₂H₁₀N₄)]_n , was synthesized solvothermally and characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The crystal structure contains two crystallographically independent Zn^II cations. Both metal cations are located on twofold axes and display distorted tetrahedral coordination geometries. Neighbouring Zn^II centres are bridged by carboxylate groups in the syn –anti mode to form one‐dimensional chains. Adjacent chains are linked through 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands to form a three‐dimensional network. In the solid state, the compound exhibits blue photoluminescence and represents a promising candidate for a thermally stable and solvent‐resistant blue fluorescent material.     

Synthesis and photovoltaic performances of benzo[1,2‐b:4,5‐b']dithiophene‐alt‐2,3‐diphenylquinoxaline copolymers pending functional groups in phenyl rings

Two donor/acceptor (D/A)‐based benzo[1,2‐b:4,5‐b′]dithiophene‐alt‐2,3‐biphenyl quinoxaline copolymers of P 1 and P 2 were synthesized pending different functional groups (thiophene or triphenylamine) in the 4‐positions of phenyl rings. Their thermal, photophysical, electrochemical, and photovoltaic properties, as well as morphology of their blending films were investigated. The poly(4,8‐bis((2‐ethyl‐hexyl)oxy)benzo[1,2‐b:4,5‐b'] dithiophene)‐alt‐(2,3‐bis(4′‐bis(N,N‐bis(4‐(octyloxy) phenylamino)‐ 1,1′‐biphen‐4‐yl)quinoxaline) ( P 2) exhibited better photovoltaic performance than poly(4,8‐bis((2‐ethylhexyl)oxy)benzo[1,2‐b:4,5‐b'] dithiophene)‐alt‐(2,3‐bis(4‐(5‐octylthiophen‐2‐yl)phenyl)quinoxaline) ( P 1) in the bulk‐heterojunction polymer solar cells with a configuration of ITO/PEDOT:PSS/polymers: [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM)/LiF/Al. A power conversion efficiency of 3.43%, an open‐circuit voltage of 0.80 V, and a short‐circuit current of 9.20 mA cm^?2 were achieved in the P 2‐based cell under the illumination of AM 1.5, 100 mW cm^?2. Importantly, this power conversion efficiency level is 2.29 times higher than that in the P 1‐based cell. Our work indicated that incorporating triphenylamine pendant in the D/A‐based polymers can greatly improved the photovoltaic properties for its resulting polymers.     

Synthesis and Photovoltaic Properties of Cyclopentadithiophene‐Based Low‐Bandgap Copolymers That Contain Electron‐Withdrawing Thiazole Derivatives

We have synthesized four types of cyclopentadithiophene (CDT)‐based low‐bandgap copolymers, poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PehCDT‐BT ), poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(2,2′‐bithiazole‐5,5′‐diyl)] ( PocCDT‐BT ), poly[{4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl}‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PehCDT‐TZ ), and poly[(4,4‐dioctyl‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐{2,5‐di(thiophen‐2‐yl)thiazolo[5,4‐d]thiazole‐5,5′‐diyl}] ( PocCDT‐TZ ), for use in photovoltaic applications. The intramolecular charge‐transfer interaction between the electron‐sufficient CDT unit and electron‐deficient bithiazole (BT) or thiazolothiazole (TZ) units in the polymeric backbone induced a low bandgap and broad absorption that covered 300 nm to 700–800 nm. The optical bandgap was measured to be around 1.9 eV for PehCDT‐BT and PocCDT‐BT , and around 1.8 eV for PehCDT‐TZ and PocCDT‐TZ . Gel permeation chromatography showed that number‐average molecular weights ranged from 8000 to 14 000 g mol^?1. Field‐effect mobility measurements showed hole mobility of 10^?6–10^?4 cm² V^?1 s^?1 for the copolymers. The film morphology of the bulk heterojunction mixtures with [6,6]phenyl‐C₆₁‐butyric acid methyl ester (PCBM) was also examined by atomic force microscopy before and after heat treatment. When the polymers were blended with PCBM, PehCDT‐TZ exhibited the best performance with an open circuit voltage of 0.69 V, short‐circuit current of 7.14 mA cm^?2, and power conversion efficiency of 2.23 % under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW cm^?2).     

A concise and efficient synthesis of amino‐substituted (1H‐benzo[d]imidazol‐1‐yl)pyrimidine hybrids: synthetic sequence and the molecular and supramolecular structures of six examples

A concise and efficient synthesis of a series of amino‐substituted benzimidazole–pyrimidine hybrids has been developed, starting from the readily available N⁴‐(2‐aminophenyl)‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine. In each of N⁵‐benzyl‐6‐methoxy‐4‐(2‐phenyl‐1H‐benzo[d]imidazol‐1‐yl)pyrimidine‐2,5‐diamine, C₂₅H₂₂N₆O, (I), 6‐methoxy‐N⁵‐(4‐methoxybenzyl)‐4‐[2‐(4‐methoxyphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₇H₂₆N₆O₃, (III), 6‐methoxy‐N⁵‐(4‐nitrobenzyl)‐4‐[2‐(4‐nitrophenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₅H₂₀N₈O₅, (IV), the molecules are linked into three‐dimensional framework structures, using different combinations of N—H…N, N—H…O, C—H…O, C—H…N and C—H…π hydrogen bonds in each case. Oxidative cleavage of 6‐methoxy‐N⁵‐(4‐methylbenzyl)‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, (II), with diiodine gave 6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, which crystallized as a monohydrate, C₁₉H₁₈N₆O·H₂O, (V), and reaction of (V) with trifluoroacetic acid gave two isomeric products, namely N‐{5‐amino‐6‐methoxy‐6‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐2‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as an ethyl acetate monosolvate, C₂₁H₁₇F₃N₆O₂·C₄H₈O₂, (VI), and N‐{2‐amino‐6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐5‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as a methanol monosolvate, C₂₁H₁₇F₃N₆O₂·CH₄O, (VIIa). For each of (V), (VI) and (VIIa), the supramolecular assembly is two‐dimensional, based on different combinations of O—H…N, N—H…O, N—H…N, C—H…O and C—H…π hydrogen bonds in each case. Comparisons are made with some related structures.     

Studies on the Reactivity of Amino‐1‐(6‐phenyl‐pyridazin‐3‐yl)‐1H‐pyrazole‐4‐carboxylic Acid Hydrazide Towards Some Reagents for Biological Evaluation

Novel 5‐amino‐1‐(6‐phenyl‐pyridazin‐3‐yl)‐1H‐pyrazole‐4‐carboxylic acid ethyl ester ( 2 ) was formed using (6‐phenyl‐pyridazin‐3‐yl)‐hydrazine ( 1 ) and ethyl(ethoxymethylene)cyanoacetate. The β‐enaminoester derivative 2 was in turn used as precursor for the preparation of 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazoles ( 3 , 4 , 7 , 8 , 9 , 10 , 11 , 12 , 15 , 16 ), 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazolo[3,4‐d]pyrimidines ( 5 , 6 , 14 ) and 1‐(6‐phenyl‐pyridazin‐3‐yl)‐pyrazolo[3,4‐d][1,2,3]triazine ( 13 ). The in vitro antimicrobial activity of the synthesized compounds was evaluated by measuring the inhibition zone diameters where some of them showed potent antimicrobial activity in compared with well‐known drugs (standards).     

Honeycomb‐like Ordered Assembly of DNA Induced by Flexible Binuclear Ruthenium(II)–Polypyridyl Complexes

A series of binuclear ruthenium(II)–polypyridyl complexes of the type [Ru₂(N‐N)₄(BPIMBp)]⁴⁺, in which N‐N is 2,2′‐bipyridine (bpy; 1 ), 1,10‐phenanthroline (phen; 2 ), dipyrido[3,2‐d:2′,3‐f] quinoxaline (dpq; 3 ), dipyrido[3,2‐a:2′,3′‐c] phenanzine (dppz; 4 ), and 1,4′‐bis[(2‐pyridin‐2‐yl)‐1H‐imidazol‐1‐yl)methyl]‐1,1′‐biphenyl (BPIMBp) is a bridging ligand, have been synthesized and characterized. These complexes are charged (4+) cations and flexible due to the ?CH₂ group of the bridging ligand and possess terminal ligands with variable intercalative abilities. The interaction of complexes 1 – 4 with calf thymus DNA (CT‐DNA) was explored by using UV/Vis absorption spectroscopy, steady‐state emission, emission quenching with K₄[Fe(CN)₆], ethidium bromide displacement assay, Hoechst displacement assay, and viscosity measurements and revealed a groove‐binding mode for all the complexes through a spacer and an intercalative mode for complexes 3 and 4 . A decrease in the viscosity of DNA revealed bending and coiling of DNA, an initial step toward aggregation. Interestingly, a distinctive honeycomb‐like ordered assembly of the DNA–complex species was visualized by fluorescence microscopy in the solution state. The use of SEM and AFM confirmed the disordered self‐organization of the DNA–complex adduct on evaporation of the solvent. The small orderly nanosized DNA aggregates were confirmed by means of circular dichroism, dynamic light scattering (DLS), and TEM. These complexes are moderately cytotoxic against three different cell lines, namely, MCF‐7, HeLa, and HL‐60.     

Facile fabrication of redox‐active and electrochromic poly(amide‐amine) films through electrochemical oxidative coupling of arylamino groups

Two novel electropolymerizable monomers, namely 3,5‐bis(4‐diphenylaminobenzamido)‐N‐[4‐(carbazol‐9‐yl)phenyl]benzamide ( 5 ) and 3,5‐bis(4‐diphenylaminobenzamido)‐N‐[4‐(3,6‐dimethoxycarbazol‐9‐yl)phenyl]benzamide ( 5‐MeO ), were synthesized, and their electrochemical properties were studied by cyclic voltammetry. The electron‐withdrawing amide groups efficiently blocked the radical cations delocalization between the two terminal TPA groups, rendering the electropolymerization of the TPA groups feasible. The polymer electrodeposited from monomer 5 could be further crosslinked through electro‐coupling of the carbazole groups, which showed both electrochromic and fluorescent properties (the emission of blue light (460 nm) in solid state). Both of the electro‐generated polymer films derived from 5 and 5‐MeO showed reversible electrochemical oxidation processes in the range of 0 ? 1.4 V with strong color changes and high contrast ratios in the visible and NIR regions upon electro‐oxidation. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. 2016, 54, 2476–2485