Carbazole Monomer Research Articles

Investigation of the structural and photometric properties of SnO2-incorporated polycarbazole nanocomposite for emissive layer material

Polycarbazole (PCz) has recently piqued the interest of scientists and researchers for its potential usage in the Flextronics industry owing to its flexibility and chemical stability. The goal of incorporating Tin oxide (SnO2) into PCz is to increase the photoluminescence intensity. The oxidizing agent FeCl3 was used in the presence of the carbazole monomer and SnO2 powder to synthesize the PCz/SnO2 nanocomposite. X-ray diffraction (XRD) analysis was used to conduct structural studies. Morphological and elemental analysis of as-synthesized PCz/SnO2 nanocomposite were performed using a Field Emission Scanning Electron Microscope (FE-SEM). The photoluminescence intensity of PCz/SnO2 nanocomposite is increased, indicating that it might be an efficient emissive layer material for optoelectronic devices.

Synthesis and Some Electrochemical Properties of Carbazole Derivative Monomers for Optoelectronic Device Design

Low-cost instruments are used to achieve high sensitivity, accuracy and precision with electrochemical techniques, making them the most suitable analytical methods used to investigate the electrochemical properties of a new molecule. Among these techniques, cyclic voltammetry, which is widely employed, allows for the determination of electronic characteristics such as molecular energy levels and orbital structure, redox properties, sensor capabilities, surface activity, and more. The carbazole molecule can undergo derivatization from various positions, allowing for alterations in its electrical and optical properties. These compounds serve as heterocyclic building blocks that can be utilized as materials for organic sensitizers and semiconductors in optoelectronic devices. Due to the presence of a hydrogen atom in the nitrogen-hydrogen (N-H) bond within the carbazole structure, which can be replaced with different functional groups, carbazole is highly suitable for nitrogen-based derivatization studies. In this study, two different carbazole monomers (IIa and IIIa), which could be potential optoelectronic, were synthesized using the Ullman and Suzuki-Miyaura reaction and characterized using 1H NMR, 13C NMR, UV-Vis, and Flouresence spectroscopy techniques. The cyclic voltammetry experiments were performed using three different working electrodes (Au, Gc, Pt disk electrodes) for each compound. Since the optimum oxidation of the compounds was obtained from the voltammograms on the gold disk electrode, this electrode was used in the calculation of energy levels. HOMO and Eg values of the compounds were deduced from cyclic voltammetry experiments and the optical absorption bands, respectively.

A novel type of multifunctional pRM@Au-Ni micromotor for screening of Hg2+ heavy metal ion

We reported the fabrication of a novel type of conducting polymer-based magnetic-driven tubular micromotor that exhibited steerable motion in water and selectivity of Hg2+ heavy metal ion with multifunctional signals. Rhodamine-based carbazole (RM) monomer was synthesized and characterized. The production strategy of the new type of pRM@Au-Ni micromotor is based on the formation of rhodamine-based carbazole conductive polymer (pRM) first by electrochemical polymerization of RM over electroactive carbazole groups, then the formation of Au and Ni layers, with the aid of the technique of electrodeposition of layers into the membrane template. In this way, pRM@Au-Ni micromotor exhibited great sensitivity to Hg2+ via changes in the fluorescence intensity, micromotor speed, and electrochemical signals as a multifunctional platform. pRM@Au-Ni micromotor showed low detection of 1.0 × 10−11 M according to fluorescence intensity, micromotor speed, and electrochemical signals. Besides, the magnetic properties of the pRM@Au-Ni control the Hg2+ direction under an external magnetic field, so it has purification potential conveniently separate the Hg2+ heavy metal ion from the water. As a mobile environment cleaning platform, the pRM@Au-Ni micromotor will be a very promising alternative for the simple, rapid, and selective detection and removal of Hg2+ heavy metal ions with multi signals.

Carbazole-involved conjugated microporous polymer hollow spheres for selective photocatalytic oxidation of benzyl alcohol under visible-light irradiation

Conjugated microporous polymers (CMPs) have been considered a type of promising visible-light-driven, organic photocatalysts. However, apart from designing high-performance CMPs from a molecular perspective, little attention is paid to improving the photocatalytic properties of these polymers through macrostructural regulation. Herein, we prepared a kind of hollow spherical CMPs involving carbazole monomers and studied their performance on the selective photocatalytic oxidation of benzyl alcohol under visible light irradiation. The results demonstrate that the introduction of a hollow spherical structure improves the physicochemical properties of the as-designed CMPs, including the specific surface areas, optoelectronic characteristics, as well as photocatalytic performance, etc. In particular, the hollow CMPs can more effectively oxidize benzyl alcohol compared to pristine ones under blue light illumination, and produce >1 mmol of benzaldehyde in 4.5 h with a yield of up to 9 mmol·g−1·h−1, which is almost 5 times higher than that of the pristine ones. Furthermore, such hollow architecture has a similar enhanced effect on the oxidation of some other aromatic alcohols. This work shows that the deliberate construction of specific macrostructures can better arouse the photocatalytic activity of the as-designed CMPs, which will contribute to the further use of these organic polymer semiconductors in photocatalysis areas.

A comprehensive overview of carbazole-EDOT based electrochromic copolymers: A new candidate for carbazole-EDOT based electrochromic copolymer

In recent years, there has been an increase in the demand for the synthesis of carbazole-EDOT based electrochromic copolymers since this combination of structures facilitates the obtaining of a free standing film on the working electrode and improves the electrochromic properties of the polycarbazole (PC) polymer. In this study, carbazole-EDOT based copolymers with electrochromic properties in the literature were classified into three groups and the effect of changing the carbazole/EDOT order on the polymer chain on the electrochromic properties of the obtained copolymer was tried to be revealed. Moreover, as an example, a new candidate for carbazole-EDOT based electrochromic random copolymer was introduced. Carbazole and EDOT monomers were copolymerized electrochemically in nonacidic medium for a clear and basic comparison. The electrochemical and spectroelectrochemical studies show that the corresponding copolymer, poly(C-co-EDOT), contains freestanding property on working electrode and shows multielectrochromic property. The copolymer gave a λmax value at about 545 nm with a band gap of 1.74 eV. As expected, EDOT monomer inserting to the polycarbazole chain improves electrochemical and optical properties of homopolymer PC. The electrochromic performance of new copolymer was also compared with its homopolymers components (polymer of carbazole (C) and EDOT) and carbazole-EDOT based electrochromic random copolymers in literature. The experiments showed that poly(C-co-EDOT) was an electroactive material with higher coloration efficiency (CE) (258 cm2/C at 900 nm) than that of PC and carbazole-EDOT based random copolymers in literature. DFT theoretical and experimental calculations were also achieved in order to find HOMO and LUMO energy levels besides band gap and compared with each other. No such a theoretical calculation related electrochromic PC polymer and that kind of random electrochromic copolymer has ever been encountered in the studies carried out so far. Since this research is a baseline study for the valuable design of carbazole-EDOT based electrochromic copolymer, it is thought to shed light on the scientists who will work on this subject in the future.

Electrochemical Synthesis of Polycarbazole Film in Nonacidic Medium and its Electrochromic Properties

This study is about the electrochemical polymerization of the monomer of carbazole, whose anodic polymerization is very common in the literature. When the studies in the literature were examined, it was seen that the electrochromic properties of carbazole were not examined. For this purpose, electrochemical and optical properties were investigated in detail by polymerizing carbazole on both glassy carbon and ITO glass electrodes in 0.1 M TABPF6/ DCM medium using the cyclic voltammetry method. The polymer film synthesized by electroanalytical methods showed reversible electrochemical oxidation process properties as well as electrochromic properties. The polymer film synthesized by electroanalytical methods showed reversible electrochemical oxidation process properties as well as electrochromic properties. Considering that this study will form a basis for other studies, it is thought that the evaluation of carbazole monomer in terms of its electrochromic properties will provide a great deal to the literature.

Nano MnOx encapsulated pyrrole-carbazole copolymer and polyvinyl chloride/carbon-coated flexible electrodes for solid-state supercapacitor cell

Pyrrole (Py) and carbazole (Cz) monomers are polymerized simultaneously in the presence of MnOx nanoparticles synthesized chemically on a stainless steel mesh (SSM) electrode by the pulse galvanostatic method in an acetonitrile medium. The resulting p(Py-co-Cz)/MnOx composite is characterized by cyclic voltammetry EIS, GCD XPS, XRD, FESEM, BET, and TEM. Since the current is applied for short periods in the presence of both monomers, p(Py-co-Cz) copolymer chains occur in short lengths, suitable for supercapacitor electrodes. The copolymer has higher Cm and lower Rct values as well as higher porosity that improves ion transport, thus greater stability than the homopolymers. It may be due to tricyclic Cz segments located between Py segments in the chains, which inhibit degradation. During the synthesis, nano-sized MnOx is also encapsulated homogeneously into the p(Py-co-Cz) coating, where 5 % is the weight percentage of manganese. Since the composite combines the advantages of the conductive polymer and metal oxide, it has the lowest Rct and highest Cm values among the coatings here. The p(Py-co-Cz)/MnOx coating with 10 mg cm−2 exhibits a high specific capacitance of 352 F g−1 at 5 A g−1 as well as flexibility, as its specific capacitance remains nearly stable (99 %) up to a bending angle of 90°. The cathode prepared from polyvinyl chloride (PVC)/activated carbon/carbon black on SSM operates within a wide voltage range of 0 to −1.5 V at 98 % cycle stability after 1000 cycles. The asymmetric cell configuration with the flexible anode and cathode electrodes provides 38 kW kg−1 and 5.28 Wh kg−1 at 5 A g−1 at a wide potential range of 2.1 V in PVA/Na2SO4 gel electrolyte, and the cycling stability was 67 % after 1000 cycles.

Honeycomb-like nitrogen-doped porous carbon nanosphere encapsulated ultrafine Pd nanoparticles for selectively catalyzing hydrogenation of cinnamaldehyde in water

In this study, a facile method was developed to synthesize honeycomb-like nitrogen-doped porous carbon nanospheres encapsulated ultrafine Pd nanoparticles (Pd/H-NPCNs) by a combination of one-step Friedel-Crafts reaction between carbazole and benzylamine monomers and subsequent in-situ impregnation-pyrolysis reduction strategy. The obtained Pd/H-NPCNs are further treated with H2O2 to remove carbon layer from the surface of metal to produce Pd/H-NPCNs-H2O2 catalyst. Owing to the high surface area, hierarchically porous structure and special honeycomb-like morphology, the Pd/H-NPCNs-H2O2 catalyst shows the excellent catalytic performance in the selective hydrogenation of cinnamaldehyde (CAL) under mild reaction conditions and water as a green solvent.

PCz/BaO nanocomposites: Synthesis, characterization, and energy storage properties

This study focuses on both synthesis and structural characterization of polycarbazole/barium oxide (PCz/BaO) nanocomposites and the determination of their frequency-based electrical properties such as complex permittivity, tangent loss, and alternating current (ac) conductivity. While PCz was synthesized by using carbazole monomers, BaO nanoparticles (NPs) were obtained by using the co-precipitation method. PCz matrix and BaO NPs were examined by scanning and transmission electron microscopes, X-ray diffraction, and Fourier Transformed Infrared Spectroscopy methods. The electrical properties of the PCz/BaO nanocomposites showed that the energy storage ability of the PCz can be improved with the addition of BaO NPs up to 10 wt% at the low frequencies. Furthermore, the 2.5 wt% BaO NPs contribution causes an increase in ε′ and a decrease in ε'' of PCz. Additionally, it has been determined that BaO NPs doping significantly increases the ac conductivity of the PCz matrix in the low- and mid-frequency regions.

Electro-oxidation of formic acid on composites from polycarbazole and WO3

Direct oxidation of formic acid (FA) is reported in the present work on a low-cost, noble metal-free WO3 embedded polycarbazole nanocomposite (PCz-WO3) electrocatalyst. Nano WO3 component used herein is synthesized by a facile coprecipitation method and then various PCz nanocomposites are synthesized at the interface of two immiscible liquids by introducing different amounts of nano WO3 during the polymerization of an optimized amount of carbazole monomer. Further, these materials are used as an active material to modify commercially available glassy carbon electrodes (GCE) and then applied for the electro-oxidation of FA at ambient conditions. It is observed that due to optimal synergism between PCz and nano WO3, PCz-WO3/4 nanocomposite exhibits improved electro-activity with direct oxidation dominated FA oxidation at the lowest potential in comparison to other counterparts and earlier reported works.

Experimental and theoretical investigation of the substitution effects on N-substituted carbazole derivatives functionalized with azomethine bonds

Examining the structural, spectroscopic, and electronic properties of molecules using both theoretical and experimental methods allow to reveal their structure-property relationship. In this study, the structural and electrochemical properties of the newly synthesized N-substituted carbazole monomers with aniline (ACA), p-methylaniline (ACMA) and pentafloroaniline (ACFA) by using a combination of experimental and computational methods have been comparatively presented. Theoretically optimized molecular structures of newly synthesized monomers have been determined by Density Functional Theory (DFT) method with 6-31G(d,p) basis set. The structural, spectroscopic, and electronic characterizations of monomers have been performed by various techniques including 1H NMR, FT-IR, and UV–Visible spectroscopy. Electrochemical polymerizations of monomers were carried out in a 0.1 M LiClO4/DCM/ACN (5:95, V: V) system. Compared to other monomers, the substitution of fluorine atoms has led to an anodic shift of the oxidation potential of the ACFA. Electrochemical and electrochromic properties of the obtained conductive polymers have been comparatively investigated by cyclic voltammetry and spectroelectrochemistry techniques. It has been observed that the poly(E)-N-(4-(9H-carbazol-9-yl) benzylidene) aniline (PACA) polymer film shows higher optical contrast, fast response time, and good electrochemical stability compared to the poly (E) N - (4- (9H-carbazol-9-yl) benzylidene) -4-methylaniline (PACMA) polymer film.

Suzuki-Miyaura Catalyst-Transfer Polycondensation of Triolborate-Type Carbazole Monomers.

Herein, we report the Suzuki–Miyaura catalyst-transfer polycondensation (SCTP) of triolborate-type carbazole monomers, i.e., potassium 3-(6-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl)triolborate (M1) and potassium 2-(7-bromo-9-(2-octyldodecyl)-9H-carbazole-2-yl) triolborate (M2), as an efficient and versatile approach for precisely synthesizing poly[9-(2-octyldodecyl)-3,6-carbazole] (3,6-PCz) and poly[9-(2-octyldodecyl)-2,7-carbazole] (2,7-PCz), respectively. The SCTP of triolborate-type carbazole monomers was performed in a mixture of THF/H2O using an initiating system consisted of 4-iodobenzyl alcohol, Pd2(dba)3•CHCl3, and t-Bu3P. In the SCTP of M1, cyclic by-product formation was confirmed, as reported for the corresponding pinacolboronate-type monomer. By optimizing the reaction temperature and reaction time, we successfully synthesized linear end-functionalized 3,6-PCz for the first time. The SCTP of M2 proceeded with almost no side reaction, yielding 2,7-PCz with a functional initiator residue at the α-chain end. Kinetic and block copolymerization experiments demonstrated that the SCTP of M2 proceeded in a chain-growth and controlled/living polymerization manner. This is a novel study on the synthesis of 2,7-PCz via SCTP. By taking advantage of the well-controlled nature of this polymerization system, we demonstrated the synthesis of high-molecular-weight 2,7-PCzs (Mn = 5–38 kg mol−1) with a relatively narrow ÐM (1.35–1.48). Furthermore, we successfully synthesized fluorene/carbazole copolymers as well as 2,7-PCz-containing diblock copolymers, demonstrating the versatility of the present polymerization system as a novel synthetic strategy for well-defined polycarbazole-based materials.

Investigation of polycarbazoles thin films prepared by electrochemical oxidation of 3- and 9-substituted carbazoles

Conducting polymers such as polycarbazole and its derivatives have attracted much attention due to their remarkable electrical and optical properties. To prepare polycarbazole derivatives, a variety of substituents can be added to the nitrogen atom of the carbazole monomers or to their 3- and 6-positions. In the present study, carbazole monomers bearing hydrogen, methyl or benzyl group at the N-position and styryl or (naphthalen-1- or -2-yl)vinyl substituents at the 3-position were synthesized. Then, the electro-oxidation of the different carbazole derivatives was carried out in acetonitrile with potentiodynamic and potentiostatic electrochemical methods. Although all monomers were successfully electrochemically oxidized, leading to the formation of polymer films on the working electrode surface, the electrochemical behavior, electrochromic properties, morphology, thickness, and roughness of the films varied greatly depending on the nature of the substituents. Among all the polycarbazole films obtained, those prepared from monomers unsubstituted at 9-position appeared to be the most promising due to their high electroactivity, electrochromism, good adhesion to the substrate and homogeneous structure.

Statistical and block conjugated polymers for bulk heterojunction solar cells: Molecular orientation, charge transfer dynamics and device performance

Two terpolymers based on fluorene, benzothiadiazole, and carbazole monomer units were investigated as electron donor materials in organic solar cells. Variation of the microstructure, either statistical or in block, significantly affected the polymers' optoelectronic properties. Both terpolymers presented a high open-circuit voltage in photovoltaic devices (ca. 0.8–0.95 V). Polymer solar cells assembled with the active layer composed of the statistical polymer combined with PCBM exhibited good photovoltaic performance, with power conversion efficiency (PCE) of 1.5% using chlorobenzene as the solvent and an annealing treatment of the active layer. In its turn, the block terpolymer showed the best result when the same solvent and the additive 1,8-diiodooctane (DIO) were used in the mixture. After introducing the additive in the preparation of the active layer, changing the solvent to dichlorobenzene, and varying the ratio of donor to acceptor, i.e., block polymer:PC60BM, the device showed PCE of 1.2% and 2.2%, with ratio 1:2 and 1:1 w/w, respectively. To better understand the different devices' performance, spectroscopic techniques were employed to gain information on the electronic structure, morphology, and dynamic processes of the polymeric films' charge transfer.

Preparation of poly(carbazole-TEMPO) electrode and its electrochemical performance

Carbazole monomer with a side chain nitroxyl radical 4-(9H-carbazol-9-yl)acetyl-oxy-2,2,6,6-tetramethylpiperidin-1-yloxy (Cz-TEMPO), was designed and synthesized successfully. The corresponding polymer electrode poly(carbazole-TEMPO) (PCz-TEMPO) has been electrochemically prepared in CH3CN solution with different supporting electrolytes. PCz-TEMPO film was homogeneously dispersed on the surface of Pt electrode and characterized by FTIR, SEM, XPS and element mapping. The electrocatalytic performances of PCz-TEMPO electrode for oxidation of benzyl alcohol were investigated by cyclic voltammetry and in situ FTIR spectroscopy. Tetrabutylammonium tetrafluoroborate (TTFB) was the most efficient supporting electrolyte for preparing PCz-TEMPO electrode among the four supporting electrolytes. In addition, the electroactivity of PCz-TEMPO-TTFB electrode remained 94.6% after 100 scanning cycles in 0.1 M NaClO4/CH3CN solution.

One-step synthesis of N-containing hyper-cross-linked polymers by two crosslinking strategies and their CO2 adsorption and iodine vapor capture

Here, a series of N-containing hyper-cross-linked polymers (HCPs) were synthesized from triphenylamine (TPA) or/and carbazole (Cz) monomers by one-step crosslinking reactions including Scholl coupling and solvent knitting Friedel-Crafts. Especially, the two reactions were also performed separately under adding both of TPA and Cz, and prepared HCP3 and HCP6. Notably, HCP1, HCP2, HCP3 prepared by Scholl coupling possessed better porosity with the Brunauer-Emmett-Teller (BET) surface areas (SBET) of 199.9–534.5 m2/g and micropore volume (Vmicro) of 0.088–0.24 cm3/g, while HCP4, HCP5, and HCP6 synthesized by solvent knitting Friedel-Crafts had inferior SBET (10.8–34.8 m2/g) with meso/macroporous structure. In addition, these HCPs displayed high N contents, various morphologies, and different hydrophobicity. Interestingly, HCP1 ~ HCP3 exhibited high CO2 uptake (104.7–116.3 mg/g) and acceptable CO2/N2 selectivity at 273 K and 1.0 bar, and large isosteric heat of adsorption (Qst) (28.0–46.7 kJ/mol), while the HCP4 ~ HCP6 showed the larger I2 vapor uptake (254.2–324.8 wt%) at 351 K and 1.0 bar than HCP1 ~ HCP3 (136.5–185.6 wt%). The results indicated the porosity especially microporosity played an important role on CO2 capture, while the SBET was not always the dominated factors for I2 vapor adsorption due to the predominant chemical interaction by electrons transfer, and the chemical structure of polymer skeletons should make the large contribution. This work will develop multifunctional polymers prepared by the facile synthetic method, and make a promising adsorbents for CO2 and iodine capture.

Electropolymerization of robust conjugated microporous polymer membranes for rapid solvent transport and narrow molecular sieving

Pore size uniformity is one of the most critical parameters in determining membrane separation performance. Recently, a novel type of conjugated microporous polymers (CMPs) has shown uniform pore size and high porosity. However, their brittle nature has prevented them from preparing robust membranes. Inspired by the skin-core architecture of spider silk that offers both high strength and high ductility, herein we report an electropolymerization process to prepare a CMP membrane from a rigid carbazole monomer, 2,2’,7,7’-tetra(carbazol-9-yl)-9,9’-spirobifluorene, inside a robust carbon nanotube scaffold. The obtained membranes showed superior mechanical strength and ductility, high surface area, and uniform pore size of approximately 1 nm. The superfast solvent transport and excellent molecular sieving well surpass the performance of most reported polymer membranes. Our method makes it possible to use rigid CMPs membranes in pressure-driven membrane processes, providing potential applications for this important category of polymer materials.

Synthesis and photoluminescence properties of polycarbazole/tin oxide (PCz/SnO2) polymer nanocomposites

In this article, polycarbazole/tin oxide polymer nanocomposites were synthesized by an in-situ chemical polymerization of carbazole monomers using anhydrous iron (III) chloride as an oxidizing agent. The influence of SnO2 filler concentration on structural properties is investigated through X-ray diffraction, field emission electron scanning microscopy, energy-dispersive X-ray and Fourier transform infra-red spectroscopy. The optical studies were performed using UV–Vis absorption and fluorescence emission spectroscopy. X-ray diffraction spectrum reveals the formation of pure polycarbazole and incorporation of tin oxide nanoparticles into the polycarbazole matrix. EDX and FTIR spectra also confirm the formation of polymer nanocomposites. The change in morphological and nodular nature with the change in the weight percentage of SnO2 is noticed from FESEM. UV–Vis absorption spectra reveal the red shift of π—π* transition of polycarbazole due to the incorporation of tin oxide into the polymer chain. From photoluminescence spectra, we have observed that fluorescence emission intensity and wavelength varies with different weight percentage of SnO2 nanoparticles. Pictorial representation of synthesis of PCz/SnO2 polymer nanocomposites

A soft template approach to various porous nanostructures from conjugated carbazole-based monomers

HypothesisControlling the size and the shape of nanostructures on surfaces is fundamental for various applications while the formation of porous structures such as nanotubes is particularly difficult. The templateless electropolymerization is a choice process that not only forms nanostructured surfaces, but also can tune their morphologies using different monomers. ExperimentsIn this work, we used this soft-template and surfactant free electropolymerization in organic solvent to deposit for the first time carbazole-based monomers. Five different conjugated carbazole-based monomers are tested here. FindingsWe show that the shape of surfaces nanostructures is highly dependent on the amount of water present in the organic solvent and on the molecular structure of the carbazole monomers. Different morphologies are obtained from fibers to vertically aligned nanotubes and even porous membranes, depending on the monomer and on the electropolymerization method. The nanostructured surfaces reach superhydrophobic properties and their dynamical non-wetting behavior varies with the monomer and the electrochemical parameters.

Carbazole modified oligonucleotides: synthesis, hybridization studies and fluorescence properties.

Synthesis of the novel thiophenyl carbazole phosphoramidite DNA building block 5 was accomplished in four steps using a Suzuki-Miyaura cross-coupling reaction from the core carbazole and it was seamlessly accommodated into a 9-mer DNA-based oligonucleotide by incorporation at the flanking 5'-end in combination with a central insertion of an LNA-T nucleotide. The carbazole-containing oligonucleotide was combined in different duplex hybrids, which were characterized by thermal denaturation, circular dichroism and fluorescence studies. The carbazole monomer modulates the duplex stability in various ways. Thus, monomer Z increased the thermal stability of the 9-mer towards the complementary 9-mer/15-mer DNA duplex by 4.2 °C. Furthermore, indications of its intercalation into the duplex were obtained by modeling studies and robust decreases in fluorescence emission intensities upon duplex formation. In contrast, no clear intercalating tendency was corroborated for monomer Z within the DNA/RNA hybrid duplex as indicated by moderate quenching of the fluorescence and similar duplex thermal stabilities relative to the corresponding control duplex. The recognition efficiencies of the carbazole modified oligonucleotide toward single nucleotide mismatches were studied with two 15-mer model targets (DNA and RNA). For both systems, mismatches positioned at the juxtaposition of the carbazole monomer showed pronounced deceases in thermal denaturation temperature. Steady-state fluorescence emission studies of all mismatched duplexes with incorporation of Z monomer typically displayed efficient fluorescence quenching.