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Carbon-based materials/metal hydroxide composite materials are one type of the most promising electrode materials for improving the performance of supercapacitors. They have the advantages of low cost, controllable morphology, high theoretical capacity, and excellent stability. In this study, nickel hydroxide nanosheets were grown vertically on the surface of carbon nanotubes (Ni(OH)2@CNTs) by a wet chemical method at low temperatures. The unique spatial configuration provides a larger specific surface area and exposes more electrochemically active sites, which is more conducive to improving electrochemical performance. The prominent conductivity of carbon nanotubes can quickly transfer electrons and improve the electrochemical cycling stability of the composite. The Ni(OH)2@CNTs composite exhibits excellent electrochemical performance with a specific capacitance of 1234 F g−1 at a current density of 1 A g−1 under a three-electrode system. In addition, an asymmetric supercapacitor (ASC) assembled using Ni(OH)2@CNTs as a cathode material shows an energy density of 65.63 W h kg−1 at a power density of 752.39 W kg−1 and a capacity retention rate of 85.9% after 10 000 cycles at a current density of 2 A g−1. The results indicate that Ni(OH)2@CNTs has prospects for application as a cathode material in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Efficient n-type doping remains a significant challenge in the field of organic thermoelectric materials, despite the documentation of several n-dopants. In this work, a new solution-processable n-type dopant (Py-DMBI) featuring a pyrene unit was synthesized and investigated, with the intention to improve the miscibility of the dopant and naphthalenediimide (NDI)-based conjugated polymer by utilization of the specific interaction between pyrene and the naphthalene diimide units. The results reveal that Py-DMBI shows improved charge-generation efficiency (i.e. the ratio of the number of generated charge carriers to the number of dopant molecules) toward the NDI based conjugated copolymer (PNDI2TEG-2Tz) in comparison with 4-((1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethyl-amine (N-DMBI), which is a widely used n-dopant. The Py-DMBI doped PNDI2TEG-2Tz exhibits a maximum power factor of 15.7 μW m−1 K−2 with a conductivity and Seebeck coefficient of up to 3.5 S cm−1 and −211 μV K−1, respectively. [ABSTRACT FROM AUTHOR]

A perylene five-membered ring diimide, PDI39, was developed as a new electron-deficient building block for n-type semiconductors. The π-expanded conjugated molecules containing azulenes were synthesized from PDI39. These conjugated molecules show helical geometry and near-infrared absorption up to 810 nm. [ABSTRACT FROM AUTHOR]

Molecular materials that can absorb and emit light in the near-infrared (NIR) region are attracting more and more attention in many fields. In this paper, we report the synthesis and studies of the photophysical and semiconducting properties of tetrathiafulvalene (TTF)–naphthalene diimide (NDI) fused molecules (NDITTF2, NDI2TTF and NDI2TTF3). The results reveal that all molecules show strong absorptions in the NIR region, and their absorption maxima can reach 1015 nm with molar extinction coefficients (ε) up to 66 900 M−1 cm−1 in the solution state. Moreover, NIR emissions were found for NDITTF2 and NDI2TTF either in solution or in the film state. The emission maxima in the CHCl3 solution locate at 892 nm for NDI2TTF (φ = 1.64%) and 1062 nm for NDITTF2 (φ = 0.21%). Furthermore, the thin film of NDITTF2 was found to show p-type semiconducting properties with a hole mobility up to 0.45 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

Organic and organometallic π-conjugated molecules with inherent nonlinear optical (NLO) responses have attracted great interest due to their controllable properties via rational structure modifications. However, most of the state-of-the-art materials such as porphyrins, phthalocyanines, and diacetylenes exhibit NLO responses at visible-light regions. Recently, diketopyrrolopyrrole (DPP) based donor–acceptor (D–A) type π-conjugated copolymers have been found to exhibit NLO responses which can reach up to 1064 nm. However, the design rationality of the structure toward NLO properties is not well understood. Herein, four alternating DPP-based copolymers are constructed by using the electron donors of 2-phenylpyridine for P1, 2-thienylpyridine for P2 and their Pt(II)-incorporated moieties for P1Pt and P2Pt. All copolymers display intense intramolecular charge transfer (ICT) processes, and the ICT absorption can be extended to the near-infrared (NIR) region due to the strong D–A interaction of the π-conjugated backbone. The variation tendency of optical bandgaps estimated from the onset of ICT absorption is P1 (1.60 eV) > P1Pt (1.56 eV) > P2 (1.47 eV) > P2Pt (1.44 eV). Open- and closed-aperture Z-scan experiments disclosed that all copolymers exhibit broadband (532 and 1064 nm) NLO properties due to the synergistic effect of excited state absorption and the ICT process upon excitation of 8 ns as well as 25 ps laser pulses. Pt(II)-incorporation can promote or switch the NLO properties due to the efficient triplet-state absorption introduced by the heavy-atom effect. The improvement of the NLO properties is of the order P1 < P1Pt < P2 < P2Pt, which is consistent with the decreasing trend of the copolymer bandgaps. These results will provide guidelines for the rational design of materials toward broadband NLO responses and advanced applications. [ABSTRACT FROM AUTHOR]

Engineering microwave absorption materials with absorption in multiple bands and strong absorption performance in the C-band remains challenging to date. Herein, coaxial stacking VS2 nanosheets (CSVNs) were customized via a facile one-step hydrothermal route for the first time and their microwave absorption (MA) properties were systematically investigated. The complex permittivity and conductivity of CSVNs could be tuned by regulating the hydrothermal reduction temperature. When the reaction temperature was 190 °C, the VS2 nanosheets exhibited unique dual-band absorption characteristics in the C-band and Ku-band. A minimum reflection loss value of −57 dB and an average absorption intensity exceeding 15 dB in both the C (4–8 GHz) and Ku (12–18 GHz) bands were obtained. For the optimized CSVNs, the qualified bandwidth with reflection loss less than −10 dB reached up to 7 GHz, which almost covered the whole measured range of the C- and Ku-bands. Notably, this desirable microwave absorption performance, which probably results from the good conductivity of the 1T-phase CSVNs in the 2H phase, the well-matched impedance and the multiple reflections induced by their distinctive stacking structure, demonstrates that CSVNs are potential outstanding absorbers. More importantly, this study provides an effective strategy to tune the microwave performance of CSVNs by tailoring their structures. [ABSTRACT FROM AUTHOR]

A novel polyoxometalate-based metal–organic framework templated by twin-Dawson clusters, [{Cu3(μ3-O)}2(trz)6Cu2(H2O)13][H1.73P2As1.73W16.27O62]·8.25H2O (1) (trz = 1,2,4-triazole), has been synthesized under hydrothermal conditions. In 1, there are two crystal distinct motifs: a 3D metal–organic nanotube framework and seven-connected Dawson clusters. It is worth mentioning that the 3D framework possesses nanotube-like channels. The twin-H1.73P2As1.73W16.27O62 clusters (abbreviated as P2(As/W)18 clusters) as templates occupy channels of the nanotube framework. To the best of our knowledge, this represents the first metal–organic nanotube framework templated by twin-Dawson clusters. The electrochemical experiments indicate that the 1-based glassy carbon electrode (1-GCE) possesses high catalytic efficiency and high stability toward reduction of inorganic bromate molecules and oxidation of the biological molecule ascorbic acid. The electrocatalytic efficiency towards the reduction of bromate in 1 M H2SO4 solution and oxidation of AA in N2 purged solution is ca. 848.4% and 896.8% (catalytic substrate: 0.5 mM), respectively. The current signal after 100 cycles exhibits almost no loss for 1-GCE. [ABSTRACT FROM AUTHOR]

Although some progress has been made in flexible supercapacitors (SCs), their high energy density, mechanical robustness, and device-level editability and programmability are still highly desirable for the development of advanced portable and miniaturized electronics, especially considering the fact that these flexible devices are likely to experience some mechanical impact and potential damage. Herein, we demonstrate the fabrication of hybrid electrodes containing self-assembled 2D metal–organic framework (MOF)/reduced graphene oxide (rGO) papers, which not only efficiently alleviate the self-restacking of rGO and the MOF but also maintain high electrical conductivity (0.32 Ω cm), excellent flexibility and mechanical properties with a Young's modulus of 34.4 GPa and a tensile strength of 89.9 MPa. In addition, a one-for-two strategy is introduced to construct two types of porous electrodes for flexible asymmetric SCs via a one MOF-derived synthesis route with simply changing metal ion precursors. As a consequence, the flexible asymmetric SCs possess a high volumetric energy density of 1.87 mW h cm−3 and an outstanding volumetric power density of 250 mW cm−3. More importantly, the all-solid-state asymmetric SCs exhibit high editability and bending-tolerance properties and perform very well under various severe service conditions, such as being seriously cut, bent, and heavily loaded. Particularly, the operations of micro-SCs with artistically designed patterns are demonstrated. Being high-strength, easily programmable and connectable in series and in parallel, the editable supercapacitor is promising for developing stylish energy storage devices to power various portable, miniaturized, and wearable devices. [ABSTRACT FROM AUTHOR]

A new selective and sensitive fluorescence turn-on detection of ClO− is reported by taking advantage of the specific reaction between a 1-methyl-1,2-dihydropyridine-2-thione unit and ClO− and the aggregation induced-emission (AIE) behavior of the tetraphenylethylene unit. [ABSTRACT FROM AUTHOR]

A fast and sensitive method was established for an in-solution selection of cancer cell-targeting peptides at “single-residue resolution” by using the switchable fluorescence of tetraphenylethylene. The selected peptides have potential for biomarker tracing and can be used for targeted delivery of different cargos into living cancer cells. [ABSTRACT FROM AUTHOR]

Since the discovery of the aggregation-induced emission (AIE) phenomenon in 2001, research on AIE molecules has drawn much attention, and this area has been expanding tremendously. This brief review will focus on recent advances in the science and application of AIE molecules, including new mechanistic understanding, new AIE molecules for sensing and imaging, stimuli-responsive AIE molecules and applications of AIE molecules for OLEDs. Moreover, this review will give a perspective on the possible opportunities and challenges that exist in the future for this area. [ABSTRACT FROM AUTHOR]

In order to demonstrate the influence of structural fine-tuning on bandgap and semiconductor performance of π-conjugated polymer materials, three new diketopyrrolopyrrole (DPP) based copolymers P1, P2 and P3 with monomers, i.e., 2-phenylpyridine, 2-(thiophen-2-yl)pyridine and 2-(thiophen-2-yl)thiazole, respectively, have been synthesized using a typical Suzuki cross-coupling polycondensation. The DFT calculations demonstrate that polymer P3 displays high backbone coplanarity in comparison to polymers P1 and P2. Absorption spectra results reveal that P3 exhibits a remarkable red-shifted absorption profile, narrow band gap and broad absorption. The thin film FET measurements show that P3 possesses the highest hole mobility (μh) up to 1.25 cm2 V−1 s−1 and on/off (Ion/off) ratio as high as 108. Those results demonstrate that the fine-tuning of the π-conjugated backbone can significantly affect the band gaps and coplanarities, and ultimately improve the semiconducting performances. [ABSTRACT FROM AUTHOR]

In this paper we report two n-type polymeric acceptors P1 and P2 based on imide/amide-derivatives (PDI, NDI and DPP). P1 and P2 exhibit very different optical properties which may be related to the different molecular configuration and polymeric crystallinity. All polymer solar cells were fabricated with conventional configuration based on polymeric donor PBDTTT-C-T and P1/P2. Results reveal that devices based on P1 show the best performance with a PCE of 2.01%, a VOC of 0.68 V, a JSC of 7.06 mA cm−2 and a FF of 41.78%, which is attributed to the appropriate energy levels, relatively high electron mobility and preferable micro-phase separation. The poor performance for P2 (PCE = 0.30%) was mainly ascribed to its extremely low JSC which was probably caused by the small HOMO energy level difference between donor and P2. [ABSTRACT FROM AUTHOR]

Here, we explore the new application of an old molecule. We find that the tetraphenylethene-indolium molecule (TPE-indo) can both image the mitochondria (in the aggregated state), and indicate mitochondrial activity by the fluorescence change of TPE-indo. TPE-indo shows good photostability, longer emission wavelength, targeting effect for mitochondria, and better response to the changes of the mitochondrial membrane potential (ΔΨm). [ABSTRACT FROM AUTHOR]

We report the design and synthesis of a red fluorescent AIE light-up probe for selective recognition, naked-eye detection, and image-guided photodynamic killing of Gram-positive bacteria, including vancomycin-resistant Enterococcus strains. [ABSTRACT FROM AUTHOR]

In this paper, we report two conjugated molecules 1 and 2 with four diketopyrrolopyrrole (DPP) moieties, which are linked by [2,2]paracyclophane. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of 1 and 2 were estimated from the respective onset oxidation and reduction potentials, which were determined on the basis of cyclic voltammetric data. Both 1 and 2 exhibit strong absorption in the visible region. Blended thin films of 1 and 2 with P3HT (poly(3-hexylthiophene)) in different weight ratios were utilized as active layers to fabricate solar cells. The results reveal that blended thin films of P3HT/1 and P3HT/2 at a weight ratio of 2 : 1 yielded the best photovoltaic performance with power conversion efficiencies (PCEs) up to 1.33% and 1.84% after thermal annealing. Blended thin films of P3HT/1 and P3HT/2 were characterized by XRD (X-ray diffraction) and AFM (atomic force microscopy) techniques. The low degree of inter-chain packing order and poor thin-film morphology are responsible for the relatively low PCEs. [ABSTRACT FROM AUTHOR]

A new sensitive fluorescence turn-on detection of gamma-radiation is reported by taking advantage of aggregation induced-emission (AIE) behaviour of the tetraphenylethylene unit and the cascade radiochemical and protonation reactions. [ABSTRACT FROM AUTHOR]

DNA nanodevices capable of “NOR” and “NAND” logic operations were developed using enzymatic reactions to generate an acidic pH gradient and drive the conformation change of cytosine-rich DNA. Due to the high selectivity and sensitivity of the enzymatic reactions in driving DNA logic gates, novel fluorescent biosensors were further designed for enzyme activity assay and glucose sensing. [ABSTRACT FROM AUTHOR]

We design a new yellow phosphor with high quantum yield by immobilizing a preselected chromophore into a rigid framework. Coating a blue light-emitting diode (LED) with this compound readily generates white light with high luminous efficacy. The new yellow phosphor demonstrates great potential for use in phosphor-converted white LEDs. [ABSTRACT FROM AUTHOR]

In this paper we report two DPP-based conjugated molecules DPPBT and DPPTT in which the respective electron withdrawing moieties 2,1,3-benzothiadiazole and thiazolo[5,4-d]thiazole are flanked by two DPP moieties. For comparison, DPPBZ containing 1,4-diethynylbenzene and two DPP moieties were synthesized. HOMO/LUMO energies of DPPBT, DPPTT and DPPBZ were estimated on the basis of cyclic voltammetric data. Owing to the fact that LUMO energies of DPPBT and DPPTT were lowered to ca.−3.5 eV, thin films of both DPPBT and DPPTT exhibit ambipolar semiconducting properties under N2 atmosphere with hole and electron mobilities up to 0.25 cm2 V−1 s−1 and 0.09 cm2 V−1 s−1, respectively. In comparison, thin film of DPPBZ just shows p-type semiconducting property. Notably, ambipolar semiconductors with relatively high carrier mobility are rarely reported for DPP-containing small conjugated molecules. Alternatively, both DPPBT and DPPTT can function as electron donors for photovoltaic materials. Thin films of DPPTT:PC71BM and DPPBT:PC71BM at a weight ratio of 1 : 1 exhibit PCEs of 4.18% and 2.44%, respectively, with VOC higher than 0.95 V. [ABSTRACT FROM AUTHOR]

A new naphthalene diimide (NDI) derivative 4NH2-NDI was synthesized and investigated. The introduction of four amino groups at core position endows 4NH2-NDI with a high HOMO energy (−4.87 eV). The organic field effect transistor (OFET) results reveal that 4NH2-NDI behaves as a p-type semiconductor with a rather low hole mobility of 8.2 × 10−5 cm2 V−1 s−1. However, its hole mobility can be enhanced significantly after doping with N,N-dihexyl naphthalene diimide (DHNDI). More interestingly, the blend thin films of 4NH2-NDI and DHNDI exhibit ambipolar behavior based on the respective transfer and output characteristics measured in an inert atmosphere, and hole and electron mobilities can reach 0.01 cm2 V−1 s−1 and 0.001 cm2 V−1 s−1, respectively, when the molar ratio of 4NH2-NDI and DHNDI is 1 : 3. [ABSTRACT FROM AUTHOR]

New conjugated D–A molecules BTBID, BFBID, TBID, 2BIDBDT and 2BIDBT with (E)-[4,4′-biimidazolylidene]-5,5′(1H,1′H)-dione (BID) moieties are reported. Based on the respective absorption spectra and redox potentials, their HOMO (−5.30 to −5.52 eV), LUMO (−3.81 to −3.86 eV) and bandgaps (1.46–1.68 eV) were estimated. The HOMO energies and bandgaps could be effectively modulated by extending the conjugation length. The crystal structure of BTBID was presented. Intermolecular electron donor–donor interactions are present, but the intermolecular electron donor–acceptor interactions do not exist within the crystal. OFETs with thin-films of these conjugated molecules were fabricated with conventional solution-processed techniques, and p-type semiconducting properties were observed. Compared to BTBID and BFBID, thin-films of TBID, 2BIDBDT and 2BIDBT exhibit relatively high hole mobilities, reaching 0.037 cm2 V−1 s−1, 0.022 cm2 V−1 s−1 and 0.020 cm2 V−1 s−1 after thermal annealing, even though the thin-films of 2BIDBDT and 2BIDBT possess poor morphologies. [ABSTRACT FROM AUTHOR]

Among the reported organic n-type semiconductors, naphthalene diimide (NDI) derivatives have received increasing attention. In this paper, we report four non-symmetric core-expanded NDI derivatives 1–4. Electrochemical, absorption spectral and theoretical calculation studies show that LUMO energies of 1–4 are lower than that of parent NDI without substitution. OFET devices based on thin films of 1–4 which can be easily solution-processed are fabricated with conventional techniques and they show n-type semiconducting behaviours. Moreover, the performance of OFET devices of 1–4 can be significantly improved by annealing their thin films. OFETs of 3 exhibit electron mobility up to 0.17 cm2 V−1 s−1 with high on/off ratio (under ambient conditions) after annealing. [ABSTRACT FROM AUTHOR]

Based on the consideration that compound 1 with a –PO3H2 group can be hydrolyzed into compound 3 which shows low solubility in aqueous solutions and thus aggregation can occur easily, a new fluorescence turn-on assay has been constructed for alkaline phosphatase (ALP) with compound 1. ALP at concentrations as low as 18 mU mL−1 can be assayed with compound 1. Moreover, compound 1 has been successfully applied for ALP assay in living cells. Also, compound 1 is useful for screening inhibitors of ALP. [ABSTRACT FROM AUTHOR]

Among the reported organic n-type semiconductors naphthalene diimide (NDI) derivatives have received more and more attention. In this paper, we report two sulfur-rich expanded NDI derivatives 1and 2containing 1,3-dithiole-2-thione-4,5-dithiolate and 1,3-dithiole-2-one-4,5-dithiolate units, respectively. Electrochemical, absorption, spectral and theoretical calculation studies show that LUMO energies of 1and 2are lower than that of a typical NDI without functional substitution. OFET devices based on thin-films of 1and 2which can be easily solution-processed are fabricated with conventional techniques. The performance of OFET devices of 1and 2can be significantly improved by fast annealing (about 30 s) their thin-films in air, with high on/off ratios (106–107) and relatively high electron mobilities of up to 0.05 and 0.04 cm2V−1s−1, respectively. [ABSTRACT FROM AUTHOR]

The metal ion-promoted intramolecular electron transfer within TTF-based dyad 1containing a photochromic PNQ unit can be switched on with UV light irradiation by taking advantage of the photochromic feature of the PNQ unit and the fact that the transand anaforms of PNQ show different electron accepting capacity. [ABSTRACT FROM AUTHOR]

A new electrochemical sensor was demonstrated for selective sensing of 3,4-dihydroxyphenylacetic acid (DOPAC) through a non-oxidative mechanism by using single-walled carbon nanotubes (SWNTs) as the electronic transducer and a synthetic cyclophane electron acceptor as the recognition element. [ABSTRACT FROM AUTHOR]

Effective separation and rapid transfer of photogenerated electron-hole pairs are key features of photocatalytic materials with high catalytic activity, which could be achieved in co-catalysts. It is reported that the two-dimensional (2D) MoS 2 is a promising co-catalyst due to its unique semi-conductive properties and graphene-like layered structure. However, the application of MoS 2 as a co-catalyst is limited by its poor electrical conductivity. On the other hand, it is worth noting that TiO 2 possesses reactive crystal facets, which is one of the dominant mechanisms for the separation of photogenerated electron-hole pairs. In this work, we prepared MoS 2 /RGO hybrids as co-catalysts which were doped to TiO 2 with highly reactive {001} planes via the hydrothermal method. It was found that the {001}-TiO 2 /MoS 2 /RGO photocatalysts with 7 wt% MoS 2 /RGO co-catalyst show the highest photodegradation activity for the degradation of Rh B under visible light irradiation ( λ > 400 nm), which could result from the synergy of the effective separation of electron-hole pairs by the {001} facets in TiO 2 and the rapid transfer of electron-hole pairs in MoS 2 /RGO. The results show that the {001}-TiO 2 /MoS 2 /RGO hybrid is a low-cost and stable photocatalyst for the effective degradation of Rh B under visible light., Competing Interests: There is no conflict in the statement., (This journal is © The Royal Society of Chemistry.)

The potential toxicity and irreversibility of radionuclide Cs place severe pressure on the natural environment, which has become one of the most forefront pollution problems in nuclear energy utilization. To solve this problem, novel self-assembled membranes consisting of two-dimensional (2D) metal-organic frameworks (MOFs) and graphene oxide (GO) were prepared by a facile filtration method, which can efficiently absorb Cs + from aqueous solutions. The batch experimental results showed that the sorption of Cs + on the GO/Co-MOF composite membrane was strongly dependent on the addition mass and the membrane compositions. Thus, the dominant interaction mechanism was interface or surface complexation and electrostatic interaction. The maximum sorption efficiency of Cs + on GO/Co-MOF was 88.4% with 8 mg addition mass at pH = 7.0 and 299 K. Detailed FT-IR and XPS analyses suggested that the efficient synergistic effects in the unique architectures of GO/Co-MOF play an important role in the high sorption capacity of Cs + . The facile preparation method and the highly-efficient Cs + removal behaviour of GO/Co-MOF make the novel membrane a promising candidate for the elimination of radionuclide contamination., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two-dimensional (2D) MoS 2 /graphene nanosheet (MoS 2 /GN) hybrids have been demonstrated to be promising microwave absorption (MA) materials due to their unique chemical and physical properties as well as rich impedance matching. However, the reported strategies for preparing MoS 2 /GN hybrids have limited their application potential due to the complex, high-cost and inefficient preparation processes. On the other hand, it is of note that the main source of graphene is based on converting insulating graphene oxides (GO) back to conductive reduced graphene oxides (RGO). Thus, the MA performance of obtained MoS 2 /RGO nanohybrids is greatly affected by the conversion process of GO. In this work, we prepared the MoS 2 /GN hybrids by a facile hydrothermal method with directly introducing highly pure and electroconductive GNs. It is found that the highest reflection loss value of the sample-wax containing 40% MoS 2 /GN is -57.31 dB at a thickness of 2.58 mm, and the bandwidth of RL values less than -10 dB can reach up to 12.28 GHz (from 5.72 to 18 GHz) when an appropriate absorber thickness between 1.5 and 4 mm is chosen. The excellent MA performances emanate from effective conjugation of MoS 2 with GN (Mo-C bond between the interfaces), which provides the dielectric loss caused by multi-relaxation, conductance, and polarization. Taking into account the facile synthesis route and their excellent MA performance, the MoS 2 /GNs hybrid nanosheets and those composite materials with similar isomorphic hetero-structures are very promising for a wide range of MA applications., Competing Interests: There is no conflict in the statement., (This journal is © The Royal Society of Chemistry.)

A new selective and sensitive fluorescence turn-on detection of ClO - is reported by taking advantage of the specific reaction between a 1-methyl-1,2-dihydropyridine-2-thione unit and ClO - and the aggregation induced-emission (AIE) behavior of the tetraphenylethylene unit.