Multifunctional conjugated microporous polymers with pyridine unit for efficient iodine sequestration, exceptional tetracycline sensing and removal

Powders to Thin Films: Advances in Conjugated Microporous Polymer Chemical Sensors

Chemical sensing of harmful species released either from natural or anthropogenic activities is critical to ensuring human safety and health. Over the last decade, conjugated microporous polymers (CMPs) have been proven to be potential sensor materials with the possibility of realizing sensing devices for practical applications. CMPs found to be unique among other porous materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) due to their high chemical/thermal stability, high surface area, microporosity, efficient host-guest interactions with the analyte, efficient exciton migration along the π-conjugated chains, and tailorable structure to target specific analytes. Several CMP-based optical, electrochemical, colorimetric, and ratiometric sensors with excellent selectivity and sensing performance were reported. This review comprehensively discusses the advances in CMP chemical sensors (powders and thin films) in the detection of nitroaromatic explosives, chemical warfare agents, anions, metal ions, biomolecules, iodine, and volatile organic compounds (VOCs), with simultaneous delineation of design strategy principles guiding the selectivity and sensitivity of CMP. Preceding this, various photophysical mechanisms responsible for chemical sensing are discussed in detail for convenience. Finally, future challenges to be addressed in the field of CMP chemical sensors are discussed.

Ultra-stable hollow nanotube conjugated microporous polymer incorporating fluorenyl moieties for Co-capture of PM and CO2

Conjugated microporous polymers have a highly delocalized π-π conjugated porous skeleton connected by covalent bonds, which can combine their excellent stability with high adsorption, in order to be applied to the study of co-capture of harmful particulate matter (PM) and carbon dioxide (CO2) under high temperature and high humidity conditions. In this paper, fluorene-based coupled conjugated microporous polymers (D-CMPs) with functionalized hollow nanotubes and abundant microporous structures were proposed. Through mechanism exploration and molecular electrostatic potential (MESP) calculation, the capture efficiency, adsorption capacity and selectivity of PM and CO2 in the waste gas stream of carbon-based combustion were analyzed. The results indicate that D-CMPs, with their rigid carbon-based π-conjugated framework, exhibit excellent tolerance under prolonged high-humidity conditions, with a capture efficiency exceeding 99.87% for PM0.3 and exceeding 99.99% for PM2.5. Meanwhile, based on its chemical/thermal stability, it can realize the recycling of adsorption-regeneration. On this basis, the "slip effect" induced by the open three-dimensional hierarchical porous structure of D-CMPs significantly enhances airflow dispersion and improves gas throughput (with a minimal permeation resistance of only 15 Pa). At a pressure of 1 bar and a temperature of 273.15 K, D-CMP-2 exhibited a CO2 adsorption capacity of up to 2.69 mmol g-1. The fitting results of three isothermal adsorption models demonstrate that D-CMPs exhibit an outstanding equilibrium selectivity towards CO2. Therefore, prior to the widespread adoption of low-carbon and clean energy technologies, porous solid materials exhibiting excellent structural stability, equilibrium selectivity, environmental tolerance, and high adsorption capacity emerge as optimal candidates for the treatment of industrial waste gases.

Porous organic polymers (POPs) for environmental remediation

Modern global industrialization along with the ever-increasing growth of the population has resulted in continuous enhancement in the discharge and accumulation of various toxic and hazardous chemicals in the environment. These harmful pollutants, including toxic gases, inorganic heavy metal ions, anthropogenic waste, persistent organic pollutants, toxic dyes, pharmaceuticals, volatile organic compounds, etc., are destroying the ecological balance of the environment. Therefore, systematic monitoring and effective remediation of these toxic pollutants either by adsorptive removal or by catalytic degradation are of great significance. From this viewpoint, porous organic polymers (POPs), being two- or three-dimensional polymeric materials, constructed from small organic molecules connected with rigid covalent bonds have come forth as a promising platform toward various leading applications, especially for efficient environmental remediation. Their unique chemical and structural features including high stability, tunable pore functionalization, and large surface area have boosted the transformation of POPs into various macro-physical forms such as thick and thin-film membranes, which led to a new direction in advanced level pollutant removal, separation and catalytic degradation. In this review, our focus is to highlight the recent progress and achievements in the strategic design, synthesis, architectural-engineering and applications of POPs and their composite materials toward environmental remediation. Several strategies to improve the adsorption efficiency and catalytic degradation performance along with the in-depth interaction mechanism of POP-based materials have been systematically summarized. In addition, evolution of POPs from regular powder form application to rapid and more efficient size and chemo-selective, "real-time" applicable membrane-based application has been further highlighted. Finally, we put forward our perspective on the challenges and opportunities of these materials toward real-world implementation and future prospects in next generation remediation technology.

Photoactive conjugated microporous polymer@C60 with quencher on tailed Y-triangular DNA structure for high-performance signal-off photoelectrochemical biosensing

Herein, we synthesized a conjugated microporous polymer (CMP) decorated C₆₀ (CMP@C₆₀) with high photoelectric conversion efficiency, in which continuously repeated donor-acceptor (D-A) π electron unit within one molecule of CMP on C₆₀ could not only effectively increase the mobility of photogenerated carriers with improved electron transmission, but also constitute the cascade energy band matching with reduced electron-hole recombination. Based on the high-performance of CMP@C₆₀ for producing exciting initial photoelectrochemical (PEC) signal, a sensitive signal-off sensing platform was designed for lead ion (Pb²⁺) assay by coupling with quencher methylene blue (MB) interacting on efficient long tailed Y-triangular DNA structure (LYTD). The proposed LYTD with a tripod structure could generate six long tails in situ on its side at the same time via a simple hybridization chain reaction (HCR), providing notably grooves on electrode to accommodate quencher MB to significantly depress the signal for sensitive detection of Pb²⁺. As a result, the proposed PEC biosensor revealed excellent analysis capability with a low detection limit of 0.3 fM (S/N = 3). Additionally, it also showed satisfactory stability in the detection of tap water samples, lake water samples and clinical serum samples, manifesting great application prospect in the areas of environmental pollutant detection.

Viologen-functionalized magnetic material for the removal of Iodine and benzanthracene in an aqueous solution

The development of magnetically active adsorbents for effective iodine removal would be highly desirable to address environmental pollution and remediation. Herein, we demonstrated the synthesis of Vio@SiO₂@Fe₃O₄ as an adsorbent via surface functionalisation of electron-deficient bipyridium (viologen) units on the surface of magnetically active silica-coated magnetite (Fe₃O₄) core. This adsorbent was characterised thoroughly using various analytical techniques, such as field emission scanning electron microscopy (FESEM), thermal gravimetric analysis, Fourier transform infrared spectroscopy (FTIR), field emission transmission electron microscopy (FETEM), Brunauer-Emmett-Teller (BET) analysis and X-ray photon analysis (XPS). The removal of triiodide from the aqueous solution was monitored via the batch method. It revealed that the complete removal was achieved upon stirring for 70 min. The thermally stable and crystalline Vio@SiO₂@Fe₃O₄ displayed efficient removal capacity even in the presence of other competing ions and at different pHs. The adsorption kinetics data were analysed following the pseudo-first-order and pseudo-second-order models. Further, the isotherm experiment showed that the maximum uptake capacity of iodine is 1.38 g/g. It can be regenerated and reused over multiple cycles to capture iodine. Further, Vio@SiO₂@Fe₃O₄ displayed a good removal capacity toward toxic polyaromatic, Benzanthracene (BzA) pollutant with an uptake capacity of 2445 μg/g. This effective removal of toxic pollutants iodine/benzanthracene was attributed to the strong non-covalent electrostatic and π-π interaction with electron-deficient bipyridium units.

π-Electron-Extended Triazine-Based Covalent Organic Framework as Photocatalyst for Organic Pollution Degradation and H2 Production from Water

Herein, we report the efficient preparation of π-electron-extended triazine-based covalent organic framework (TFP-TPTPh COF) for photocatalysis and adsorption of the rhodamine B (RhB) dye molecule, as well as for photocatalytic hydrogen generation from water. The resultant TFP-TPTPh COF exhibited remarkable porosity, excellent crystallinity, high surface area of 724 m2 g−1, and massive thermal stability with a char yield of 63.41%. The TFP-TPTPh COF demonstrated an excellent removal efficiency of RhB from water in 60 min when used as an adsorbent, and its maximum adsorption capacity (Qm) of 480 mg g−1 is among the highest Qm values for porous polymers ever to be recorded. In addition, the TFP-TPTPh COF showed a remarkable photocatalytic degradation of RhB dye molecules with a reaction rate constant of 4.1 × 10−2 min−1 and an efficiency of 97.02% under ultraviolet–visible light irradiation. Furthermore, without additional co-catalysts, the TFP-TPTPh COF displayed an excellent photocatalytic capacity for reducing water to generate H2 with a hydrogen evolution rate (HER) of 2712 μmol g−1 h−1. This highly active COF-based photocatalyst appears to be a useful material for dye removal from water, as well as solar energy processing and conversion.

Natural phenol-inspired porous polymers for efficient removal of tetracycline: Experimental and engineering analysis

Efficient and feasible removal of trace antibiotics from wastewater is extremely important due to its environmental persistence, bioaccumulation, and toxicity, but still remains a huge challenge. Herein, three natural phenol-inspired porous organic polymers were fabricated from natural phenolic-derived monomers (p-hydroxy benzaldehyde, 2,4-dihydroxy benzaldehyde and 2,4,6-trihydroxy benzaldehyde) and melamine via polycondensation reaction. Characterization highlighted that the increasing contents of hydroxyl groups in monomers induced an increase of the polymer total porosity and promoted the formation of a highly microporous structure. With mesopore-dominated pore (average pore diameter 9.6 nm) and large pore volume (1.78 cm³/g), p-hydroxy benzaldehyde-based porous polymer (1-HBPP) exhibited ultra-high maximum adsorption capacity (q_max) of 697.6 mg/g for tetracycline (TC) antibiotic. Meanwhile, the porous networks and plentiful active sites of 1-HBPP enabled fast adsorption kinetics (within 10 min) for TC removal, which could be well described by the pseudo-second-order model. Dynamic adsorption studies showed that 1-HBPP could be used in fixed-bed adsorption column (FBAC) with high removal efficiency (breakthrough volume per unit mass, 13.2 L/g) and dynamic adsorption capacity (201.6 mg/g), which were much higher than other reported adsorbents. The breakthrough curves both well matched with Thomas and Yoon-Nelson models in FBAC treatment. Moreover, removal mechanism analysis affirmed that pore-filling, hydrogen bonding, electrostatic interactions and π-π stacking interactions were main driving forces for TC adsorption. The prepared natural phenol-inspired porous adsorbents show great potential in antibiotics removal from wastewater, and this strategy would promote the sustainable and high-value utilization of natural phenolic compounds.

Review of recent developments in iodine wasteform production

Radioiodine capture and immobilization is not only important to consider during the operation of reactors (i.e., I-131), during nuclear accidents (i.e., I-131 and I-129) or nuclear fuel reprocessing (i.e., I-131 and I-129), but also during disposal of nuclear wastes (i.e., I-129). Most disposal plans for I-129-containing waste forms (including spent nuclear fuel) propose to store them in underground repositories. Here, iodine can be highly mobile and, given its radiotoxicity, needs to be carefully managed to minimize long-term environmental impacts arising from disposal. Typically, any process that has been used to capture iodine from reprocessing or in a reactor is not suitable for direct disposal, rather conversion into a wasteform for disposal is required. The objectives of these materials are to use either chemical immobilization or physical encapsulation to reduce the leaching of iodine by groundwaters. Some of the more recent ideas have been to design capture materials that better align with disposal concepts, making the industrial processing requirements easier. Research on iodine capture materials and wasteforms has been extensive. This review will act as both an update on the state of the research since the last time it was comprehensively summarized, and an evaluation of the industrial techniques required to create the proposed iodine wasteforms in terms of resulting material chemistry and applicability.

Porphyrin-Based Conjugated Microporous Polymers for Highly Efficient Adsorption of Metal Ions

The capture and elimination of anions and cations from water have attracted a great deal of attention and are quite vital for clean production and environmental remediation. In this work, we present the synthesis of four porphyrin (Por)-based conjugated microporous polymers (CMPs, namely, Por-CMP-1-4), which were produced through a Sonogashira-Hagihara linked response using porphyrin and acetylene aromatic compounds as building blocks and used as absorbents to eliminate metal ions from water. The as-synthesized Por-CMP-1-4 exhibit an amorphous porous structure and outstanding caloric and physicochemical properties. Taking advantage of their larger specific surface areas, i.e., 541.47, 614.58, 382.38, and 677.90 m² g^-1 for Por-CMP-1-4, respectively, and their chelating active site that originated from the porphyrin ring, Por-CMP-1-4 show better Zn²⁺, Cu²⁺, and Pb²⁺ adsorption ability. Among them, Por-CMP-3 has the greatest adsorbability of 640 mg g^-1 for Zn²⁺, with an adsorption efficiency of 80%, whereas its adsorption capacities for Cu²⁺ and Pb²⁺ ions were both 334 mg g^-1, with an adsorption efficiency of 42% for Cu²⁺ and Pb²⁺. Employing Por-CMP-3 as a representative example, its adsorption kinetics has been systematically investigated. The adsorption behavior of Por-CMP-3 with respect to the Zn²⁺ ion is shown to exhibit pseudo-first-order kinetics and Langmuir isotherm modes. Meanwhile, the adsorption mechanism is discussed in detail, and it was thought it might be chelation, in which the nitrogen atoms with a single pair of electrons on the porphyrin ring interacted with metal ions to form stable chelation coordination bonds, thus removing metal ions selectively and effectively. Furthermore, Por-CMP-3 exhibited good reusability, retaining 60% of its Zn²⁺ removal rate after four continuous adsorptions.

Pyrene-based sulfonated organic porous materials for rapid adsorption of cationic dyes in water

Porous organic polymers (POP) have gained attention because of their high specific surface area, porosity and their simplicity in synthesis, but for the most part, they are hydrophobic because of their organic backbone, making it difficult to expand their applications. Here, we have obtained poly(pyrene) porous organic polymers (PyPOP) through the polymerization of pyrene monomers catalysed by aluminium trichloride, which is a simple and inexpensive synthesis method. The sulfonated poly(pyrene) porous organic polymers (PyPOP-SO₃H) obtained showed rapid adsorption of cationic dyes, especially malachite green (MG adsorption 1607 mg/g) and methylene blue (MB adsorption 1220 mg/g) in pH = 7 aqueous solution, room temperature. The results show that the Freundlich model is more in line with the adsorption process than the Langmuir model, whether for methylene blue or malachite green. In addition, the PSO kinetic model fits better than PFO kinetic model, whether it is for the adsorption of methylene blue or malachite green. The excellent adsorption performance of PyPOP-SO3H for cationic dyes may be due to the introduction of sulfonic acid groups, which not only increases the specific surface area but also allows better dispersion in water, increasing contact points and adsorption efficiency. This research expands the scope of exploration and application of POP.

Porous organic polymers as a platform for sensing applications

Sensing analysis is significantly important for human health and environmental safety, and has gained increasing concern. As a promising material, porous organic polymers (POPs) have drawn widespread attention due to the availability of plentiful building blocks and their tunable structures, porosity and functions. Moreover, the permanent porous nature could provide a micro-environment to interact with guest molecules, rendering POPs attractive for application in the sensing field. In this review, we give a comprehensive overview of POPs as a platform for sensing applications. POP-based sensors are mainly divided into five categories, including fluorescence turn-on sensors, fluorescence turn-off sensors, ratiometric fluorescent sensors, colorimetric sensors and chemiresistive sensors, and their various sensing applications in detecting explosives, metal ions, anions, small molecules, biological molecules, pH changes, enantiomers, latent fingerprints and thermosensation are summarized. The different structure-based POPs and their corresponding synthetic strategies as well as the related sensing mechanisms mainly including energy transfer, donor-acceptor electron transfer, absorption competition quenching and inner filter effect are also involved in the discussion. Finally, the future outlook and perspective are addressed briefly.

Machine learning-assisted array from fluorescent conjugated microporous polymers for multiple explosives recognition

The fluorescent properties of conjugated microporous polyphenylene (CMPs) were tuned through a wide range by inclusion of small amount of comonomer as chromophore in the network. The multi-color CMPs were used for explosives sensing and demonstrated broad sensitivity (ranging from -0.01888 μM^-1 to -0.00467 μM^-1) and LODs (ranging from 31.0 nM to 125.3 nM) against thirteen explosive compounds including nitroaromatics (NACs), nitramines (NAMs) and nitrogen-rich heterocycles (NRHCs). The CMPs were also developed as a sensor array for discrimination of thirteen explosives, specifically including NT, p-DNB, DNT, TNT, TNP, TNR, RDX, HMX, CL-20, FOX-7, NTO, DABT and DHT. By using classical statistical method "Linear Discriminant Analysis (LDA)", the thirteen explosives at a fixed concentration were completely discriminated and unknown test samples were indentied with 88% classification accuracy. Moreover, explosives in different concentrations and the mixtures of explosives were also successfully classified. Compared with LDA, Machine Learning algorithms have significant advantages in analyzing the array-based sensing data. Different Machine Learning models for pattern recognition have also been implemented and discussed here and much higher accuracy (96% for "neural network") can be achieved in predicting unknown test samples after training.

Heteroatom-free conjugated tetraphenylethylene polymers for selectively fluorescent detection of tetracycline

The antibiotic tetracycline (Tc) is a major contaminant in food and water, with adverse effects on both ecosystems and human health. The development of novel sensors for tetracycline detection is of great importance. In this work, we develop a novel heteroatom-free conjugated tetraphenylethylene polymer (TPE-CMP) fluorescence sensor for the detection of tetracycline. In the presence of Tc, the emission fluorescence of TPE-CMP was quenched by the photoinduced electron transfer mechanism to achieve high sensitivity. The polymers can detect tetracycline at a concentration of 0-100 μg/mL with a good linear correlation (0.99), and the limit of detection (LOD) is 1.23 μg/mL. Furthermore, TPE-CMP has excellent selectivity in detecting Tc in the presence of various anti-interference analytes, including ions and antibiotics. In addition, the practical feasibilities of TPE-CMP for Tc sensing were further investigated in milk, urine and wastewater samples with satisfactory recoveries (from 94.96% to 112.53% for milk, from 96.41% to 99.31% for urine and from 98.54% to 100.52% for wastewater). We have designed and synthesized TPE-CMP based on heteroatom-free for the specific fluorescence detection of tetracycline, expanding the range of fluorescence detection sensors and offering great promise for practical applications.

Designing Phenyl Porous Organic Polymers with High-Efficiency Tetracycline Adsorption Capacity and Wide pH Adaptability

Adsorption is an effective method to remove tetracycline (TC) from water, and developing efficient and environment-friendly adsorbents is an interesting topic. Herein, a series of novel phenyl porous organic polymers (P-POPs), synthesized by one-pot polymerization of different ratios of biphenyl and triphenylbenzene under AlCl₃ catalysis in CH₂Cl₂, was studied as a highly efficient adsorbent to removal of TC in water. Notably, the obtained POPs possessed abundant phenyl-containing functional groups, large specific surface area (1098 m²/g) with abundant microporous structure, high pore volume (0.579 cm³/g), favoring the removal of TC molecules. The maximum adsorption capacity (fitted by the Sips model) could achieve 581 mg/g, and the adsorption equilibrium is completed quickly within 1 h while obtaining excellent removal efficiency (98%). The TC adsorption process obeyed pseudo-second-order kinetics and fitted the Sips adsorption model well. Moreover, the adsorption of POPs to TC exhibited a wide range of pH (2–10) adaptability and outstanding reusability, which could be reused at least 5 times without significant changes in structure and efficiency. These results lay a theoretical foundation for the application of porous organic polymer adsorbents in antibiotic wastewater treatment.

Bifunctional conjugated microporous polymer based filters for highly efficient PM and gaseous iodine capture

Cross-linked conjugated microporous polymers (CMPs) based air filters obtained by a one-step cross-coupling reaction for effective capture of particulate matter and gaseous iodine from dusty air.

Facile metal-free synthesis of pyrrolo[3,2-b]pyrrolyl-based conjugated microporous polymers for high-performance photocatalytic degradation of organic pollutants

An efficient and metal-free approach to the synthesis of new kinds of CMPs (pyrrolo[3,2-b]pyrrolyl-based CMPs) on a gram scale within a short time has been developed for remarkable adsorbent and photocatalytic degradation of organic pollutants.

Two isomeric metal-organic frameworks bearing stilbene moieties for high volatile iodine uptake

The efficient, green, and economical removal of radioactive iodine (I2) has drawn worldwide attention in the safe development of nuclear energy. Metal-organic frameworks (MOFs) have been demonstrated to be a...

Barbituric and thiobarbituric acid-based UiO-66-NH2 adsorbents for iodine gas capture: Characterization, efficiency and mechanisms

Efficient iodine gas capture is necessitated in many industries like spent nuclear fuel off-gas treatment in view of environmental protection and resource recycling. However, the adsorption efficiency and stability of the current adsorbents are limited. In the present work, efficient and stable barbituric and thiobarbituric acid-based UiO-66-NH₂ adsorbents (i.e., UiO-66-NH-B.D and UiO-66-NH-T.D, respectively) have been synthesized by post-synthetic covalent modification. Characterization approaches, including SEM-EDS, TEM, XRD, FTIR, XPS, ¹H NMR, TGA and BET, are used to obtain information on the properties and adsorption mechanisms of these metal-organic framework (MOF) adsorbents. The kinetics and mechanisms involved are studied in detail. The treatment efficiency and recyclability of the adsorbents are checked and compared with the adsorbents reported in previous works. The results show that the current adsorbents are potentially suitable for efficient iodine gas capture. High maximum iodine adsorption amount by UiO-66-NH-B.D and UiO-66-NH-T.D (1.17 and 1.33 g/g) was achieved under 75 °C. These new adsorbents are thermally stable for iodine adsorption and regenerated and reused with good performance. The adsorption mechanisms were revealed based on experimental results, indicating that iodine is adsorbed by both physisorption and chemisorption.

Modulation of High-Spin Co(II) in Li/Co-MOFs as Efficient Fenton-like Catalysts

Developing high-performance catalysts toward the Fenton reaction is important for environmental protection and sustainable development, yet it is still challenging. The high-spin states of first-row transition metal atoms with tetrahedral coordination provide a flexible electronic environment to activate the catalyst and elevate its catalytic activity. As a type of material with adjustable structures, metal-organic frameworks (MOFs) are excellent candidate catalysts as they can accurately regulate the coordination configurations of metal ions. In this paper, we investigate and summarize the direct formation of bimetallic carboxylate Li/Co-MOFs with tetrahedral coordination metal centers in a mixed H2O/polar organic solvent system. The induction of Li(I) ions is manifested in the generation of hydroxides during the dissociation of the Co(II) solvation structure to trigger the tetrahedral coordination behavior of Co(II). These Li/Co-MOFs containing high-spin Co(II) centers can serve as highly efficient Fenton-like catalysts for organics. This study provides a promising strategy for rational design of MOF-based catalysts with high-spin metal centers for application in environment governance.

Microporous Hyper-Cross-Linked Polymers with High and Tuneable Content of Pyridine Units: Synthesis and Application for Reversible Sorption of Water and Carbon Dioxide

New hyper-cross-linked porous organic polymers (POPs) with a high content of pyridine segments (7.86 mmol pyridine g^-1 ), and a micro/mesoporous texture are reported. The networks are achieved by the chain-growth homopolymerization of 2,6- and 3,5-diethynylpyridines. The pyridine segments form links interconnecting the polyacetylene main chains in these networks. The content of pyridine segments in the networks can be tuned by copolymerizing diethynylpyridines with 1,3-diethynylbenzene. The pyridine rings in the networks serve as base and hydrophilic centers for the sorption of CO₂ and water. The homopolymer pyridine networks are highly efficient in the low-pressure adsorption/desorption of CO₂ . This sorption mode is promising for the postcombustion removal of CO₂ from the fuel gas. The poly(3,5-diethynylpyridine) network exhibits high efficiency in capturing and releasing water vapor (determined capacity 376 mg g^-1 at 298 K and relative humidity (RH) = 90% is one of the highest values reported for POPs) and is a promising material for the cyclic water harvesting from air. The reported networks are characterized by ¹³ C cross-polarization magic angle spinning NMR, thermogravimetric analysis, and N₂ adsorption/desorption and their efficiency in CO₂ and H₂ O capturing is discussed in relation to the content and type of incorporated pyridine segments.

Covalent Organic Polymers and Frameworks for Fluorescence-Based Sensors

Following the advancements and diversification in synthetic strategies for porous covalent materials in the literature, the materials science community started to investigate the performance of covalent organic polymers (COPs) and covalent organic frameworks (COFs) in applications that require large surface areas for interaction with other molecules, chemical stability, and insolubility. Sensorics is an area where COPs and COFs have demonstrated immense potential and achieved high levels of sensitivity and selectivity on account of their tunable structures. In this review, we focus on those covalent polymeric systems that use fluorescence spectroscopy as a method of detection. After briefly reviewing the physical basis of fluorescence-based sensors, we delve into various kinds of analytes that have been explored with COPs and COFs, namely, heavy metal ions, explosives, biological molecules, amines, pH, volatile organic compounds and solvents, iodine, enantiomers, gases, and anions. Throughout this work, we discuss the mechanisms involved in each sensing application and aim to quantify the potency of the discussed sensors by providing limits of detection and quenching constants when available. This review concludes with a summary of the surveyed literature and raises a few concerns that should be addressed in the future development of COP and COF fluorescence-based sensors.

Advances in Molecularly Imprinted Polymers Based Affinity Sensors (Review)

Recent challenges in biomedical diagnostics show that the development of rapid affinity sensors is very important issue. Therefore, in this review we are aiming to outline the most important directions of affinity sensors where polymer-based semiconducting materials are applied. Progress in formation and development of such materials is overviewed and discussed. Some applicability aspects of conducting polymers in the design of affinity sensors are presented. The main attention is focused on bioanalytical application of conducting polymers such as polypyrrole, polyaniline, polythiophene and poly(3,4-ethylenedioxythiophene) ortho-phenylenediamine. In addition, some other polymers and inorganic materials that are suitable for molecular imprinting technology are also overviewed. Polymerization techniques, which are the most suitable for the development of composite structures suitable for affinity sensors are presented. Analytical signal transduction methods applied in affinity sensors based on polymer-based semiconducting materials are discussed. In this review the most attention is focused on the development and application of molecularly imprinted polymer-based structures, which can replace antibodies, receptors, and many others expensive affinity reagents. The applicability of electrochromic polymers in affinity sensor design is envisaged. Sufficient biocompatibility of some conducting polymers enables to apply them as "stealth coatings" in the future implantable affinity-sensors. Some new perspectives and trends in analytical application of polymer-based semiconducting materials are highlighted.

Cellulose-assisted construction of high surface area Z-scheme C-doped g-C3N4/WO3 for improved tetracycline degradation

The preparation of heteroatom doping heterojunction photocatalysts with nontoxic carbonaceous materials and simple method still remains a challenge. Herein, ternary Z-scheme C-doped graphitic carbon nitride/tungsten oxide (C-doped g-C₃N₄/WO₃) was successfully fabricated via the hydrothermal impregnation with cellulose nanocrystal, high-temperature calcination, and electrostatic self-assembly with WO₃ nanocuboids in turns. Benefiting from the porous structure, high specific areas (57.20 m² g^-1), C-substitution, and the formation of Z-scheme heterojunction, the resulting photocatalyst exhibited narrower band-gap, enhanced visible-light absorption and separation of charge carrier, faster interfacial charge transfer, good oxidation/reduction capacities, and thus improved the photocatalytic activity performance. As such, this investigation will provide an effective route for not only incorporating semiconductors and heteroatoms into g-C₃N₄ but also developing more heterojunction with markedly improved photocatalytic performance.

Charge Transfer and Biocompatibility Aspects in Conducting Polymer-Based Enzymatic Biosensors and Biofuel Cells

Charge transfer (CT) is a very important issue in the design of biosensors and biofuel cells. Some nanomaterials can be applied to facilitate the CT in these bioelectronics-based devices. In this review, we overview some CT mechanisms and/or pathways that are the most frequently established between redox enzymes and electrodes. Facilitation of indirect CT by the application of some nanomaterials is frequently applied in electrochemical enzymatic biosensors and biofuel cells. More sophisticated and still rather rarely observed is direct charge transfer (DCT), which is often addressed as direct electron transfer (DET), therefore, DCT/DET is also targeted and discussed in this review. The application of conducting polymers (CPs) for the immobilization of enzymes and facilitation of charge transfer during the design of biosensors and biofuel cells are overviewed. Significant attention is paid to various ways of synthesis and application of conducting polymers such as polyaniline, polypyrrole, polythiophene poly(3,4-ethylenedioxythiophene). Some DCT/DET mechanisms in CP-based sensors and biosensors are discussed, taking into account that not only charge transfer via electrons, but also charge transfer via holes can play a crucial role in the design of bioelectronics-based devices. Biocompatibility aspects of CPs, which provides important advantages essential for implantable bioelectronics, are discussed.

Porous Organic Polymer Synthesized by Green Diazo-Coupling Reaction for Adsorptive Removal of Methylene Blue

A porous organic polymer (marked as DT-POP), which contains abundant free phenolic hydroxyl groups, is synthesized by the well-known green azo-coupling reaction in water, characterized, and utilized as an effective adsorbent for the elimination of methylene blue (MB) from water solutions. The presence of permanent mesopores, abundant active functional groups, and π-electron enrichment ascribed to phenyl rings make DT-POP an efficient adsorbent for MB due to strong hydrogen bonding, π-π, and electrostatic interactions with the cationic dye MB. DT-POP with high stability and high adsorption capacity can be reused many times and thus shows high applicability in pollutant disposal.

Conducting Polymers in the Design of Biosensors and Biofuel Cells

Fast and sensitive determination of biologically active compounds is very important in biomedical diagnostics, the food and beverage industry, and environmental analysis. In this review, the most promising directions in analytical application of conducting polymers (CPs) are outlined. Up to now polyaniline, polypyrrole, polythiophene, and poly(3,4-ethylenedioxythiophene) are the most frequently used CPs in the design of sensors and biosensors; therefore, in this review, main attention is paid to these conducting polymers. The most popular polymerization methods applied for the formation of conducting polymer layers are discussed. The applicability of polypyrrole-based functional layers in the design of electrochemical biosensors and biofuel cells is highlighted. Some signal transduction mechanisms in CP-based sensors and biosensors are discussed. Biocompatibility-related aspects of some conducting polymers are overviewed and some insights into the application of CP-based coatings for the design of implantable sensors and biofuel cells are addressed. New trends and perspectives in the development of sensors based on CPs and their composites with other materials are discussed.

Functional Polymers Structures for (Bio)Sensing Application-A Review

In this review we present polymeric materials for (bio)sensor technology development. We focused on conductive polymers (conjugated microporous polymer, polymer gels), composites, molecularly imprinted polymers and their influence on the design and fabrication of bio(sensors), which in the future could act as lab-on-a-chip (LOC) devices. LOC instruments enable us to perform a wide range of analysis away from the stationary laboratory. Characterized polymeric species represent promising candidates in biosensor or sensor technology for LOC development, not only for manufacturing these devices, but also as a surface for biologically active materials' immobilization. The presence of biological compounds can improve the sensitivity and selectivity of analytical tools, which in the case of medical diagnostics is extremely important. The described materials are biocompatible, cost-effective, flexible and are an excellent platform for the anchoring of specific compounds.