Fumed-Si-Pr-PNS as a Photoluminescence sensor for the Detection of Hg2+ in Aqueous Media.

Fumed silica was functionalized by piperazine followed by the reaction with 2- naphthalenesulfonyl chloride to prepare Fumed-Si-Pr-Piperazine-Naphthalenesulfonyl chloride (Fumed-Si-Pr-PNS), which was characterized to demonstrate the effective attachment on the surface of fumed silica. The optical sensing ability of Fumed-Si-Pr-PNS was studied via diverse metal ions in H2O solution by photoluminescence spectroscopy. The results showed that Fumed-Si-Pr-PNS detected selectively Hg2+ ions. The prepared sensor showed almost high absorption at different pH for Hg ion. After drawing various diagrams, The detection limits were calculated at about 12.45 × 10-6 M for Hg2+.

ZnO/black phosphorus/C3N4 composite: An effective photocatalyst for Cr (VI) reduction and degradation of rhodamine B.

The utilization of photocatalysts offers a promising approach for the removal of Cr (VI) and rhodamine dyes. Through the generation of reactive species and subsequent degradation reactions, photocatalysis provides an efficient and environmentally friendly method for the remediation of wastewater. In this study, we have synthesized an n-p-n heterojunction of carbon nitride (C3N4), zinc oxide (ZnO), and black phosphorus (BP) through the sonication-stirring method. The photocatalytic ability of this composite was examined for the decomposition rhodamine B (RhB) and detoxification of hexavalent chromium ion (up to 97% during 80 min) under Xenon irradiation. The results of trapper experiments indicated that the active species were hydroxyl radical (˙OH), electron (e-), and superoxide anion radical (˙O2-). Based on the obtained potential of the lowest unoccupied molecular orbitals (LUMO) and the highest occupied molecular orbital (HOMO) for the mentioned semiconductors, through Mutt-Schottky results, the double Z-scheme mechanism was proposed for the studied process. The electrochemical impedance spectroscopy data exhibited good charge transfer for the evaluated composite versus the pure compounds. The impressive separation of holes and electrons along with the low recombination were confirmed by the responses of photocurrent and quenching the photoluminescence (pl) intensity for the composite, respectively. The current density of the composite recorded 66.6%, 87.3%, and 92% higher than those of BP, C3N4, and ZnO, indicating an excellent electron-hole separation for the ternary composite compared to the pure semiconductors. Diffuse reflectance spectra (DRS) data revealed 2.9, 3.17, 1.15, and 2.63 eV as the band gap values for C3N4, ZnO, BP, and composite. The rate constant of the new composite to remove RhB and reduce hexavalent chromium were about 4.79 and 2.64 times higher than that of C3N4, respectively.

Black Phosphorus-based Photocatalysts: Synthesis, Properties, and Applications.

Photocatalysis is considered as an eco-friendly and sustainable strategy, since it uses abundant light for the advancement of the reaction, which is freely accessible and is devoid of environmental pollution. During the last decades, (nano)photocatalysts have gained broad industrial applications in terms of purification and detoxification of water as well as production of green fuels and hydrogen gas due to their special attributes. The degradation or remediation of toxic and hazardous compounds from the environment or changing them into non-toxic entities is a significant endeavor and necessary for the safety of humans, animals, and the environment. Black phosphorus (BP), a two-dimensional single-element material, has a marvelous structure, tunable bandgap, changeable morphology from bulk to nanosheet/quantum dot, and unique physicochemical properties, which makes it attractive material for photocatalytic applications, especially for sustainable development purposes. Since it can serve as a photocatalyst with or without coupling with other semiconductors, various aspects for multidimensional exploitation of BP are deliberated including their preparation via solvothermal, ball milling, calcination, and sonication methods to obtain BP from red phosphorus. The techniques for improving the photocatalytic and stability of BP-based composites are discussed along with their multifaceted applications for environmental remediation, pollution degradation, water splitting, N2 fixation, CO2 reduction, bacterial disinfection, H2 generation, and photodynamic therapy. Herein, most recent advancements pertaining to the photocatalytic applications of BP-based photocatalyst are cogitated, with a focus on their synthesis and properties as well as crucial challenges and future perspectives.

MOF-based composites as photoluminescence sensing platforms for pesticides: Applications and mechanisms.

Metal-organic frameworks (MOFs) have recently garnered considerable attention among reticular compounds due to their unique physicochemical properties and applications in sensing toxic compounds. On the other hand, fluorometric sensing has been widely studied for food safety and environmental protection among the various sensing methods. Thus, designing MOF-based fluorescence sensors for specific detection of hazardous compounds, especially pesticides, are incessantly needed to keep up with the continuous demands for monitoring these environmental pollution. Herein, recent MOF-based platforms for pesticide fluorescence detection are deliberated owing to sensors' emission origins and in terms of their structural properties. The influences of different guest incorporation in MOFs on pesticide fluorescence detection are summarized, and the future developments of novel MOF composites such as polyoxometalate@MOFs (POMOF), carbon quantum dots@MOFs (CDs@MOF), and organic dye@MOF are prospected for fluorescence sensing of assorted pesticides with a focus on mechanistic insights of specific detection techniques in food safety and environmental protection.

A new fluorescence probe for detection of Cu+2 in blood samples: Circuit logic gate.

A Fluorescence probe was designed based on 8-hydroxyquinoline chitosan silica precursor (HQCS) for selective detection of Al3+, Cu2+. The HQCS has no observable fluorescence signal, but after the addition of Al3+, a huge fluorescence signal appeared, and the selective quenching was absorbed after the addition of Cu2+. The effect of other different cations, including Cu2+, Mg2+, Ca2+, Pb2+, Zn2+, Hg2+, Ag+, Fe3+, and K+ was studied. The addition of Cu2+ to the probe (HQCSAL) decreased the fluorescence very repeatable, and the variation of the fluorescence vs. Cu2+ was monotonic and linear. Therefore, the prepared probe was used to determine Cu2+ ions in real samples. The mechanism of fluorescence variation by adding cations to the probe solution was studied using the Stern-Volmer equation. Under the optimum conditions, the linear range and detection limit were 3.5-31 µM and 1 µM, respectively. The probe accuracy on the copper determination in the blood and tap waters was comparable to the ICP-OES results. The circuit logic gate mimic was designed for the fluorescence behavior of the probe constituents.

Multicomponent Synthesis and Investigations Fluorescence Activity of Chromenone-Pyrazole Compounds.

A synthetic method is described to produce some chromenone-pyrazole derivatives through a one-pot multicomponent reaction using SrFe12O19 as a magnetic catalyst. This method provides quite a few merits, including the use of an effective and easy separable nanocatalyst, high yields of products, short reaction time, and easy work-up. Two of the products showed fluorescence properties, which have detected mercury ions without any interference with other ions. They can detect a tiny amount of mercury ions, which were comparable with other chemosensors. The detection limit is 4 × 10-7 and 3 × 10-8 M, respectively, for the compound I and II, respectively, which were considered very low amounts. The effect of mercury on health and environmental pollution is essential in medical science.

An On-off Supramolecular Fluorescence Switch for Detection of Pb2+ Ions and Vitamin C.

ß-cyclodextrin-hydroxyquinoline functionalized graphene oxide (GO-CD-HQ) was facilely fabricated to monitor and quantitatively analyze cations in aqueous media. The optical probe was notably selective enhanced toward Pb2+ ions over the other tested ions like Cu2+, Hg2+, Ca2+, Na+, K+, Zn2+, Fe2+, Fe3+, Ag+, Mg2+, and Cd2+ at 468 nm as an emission wavelength. The probe was shown the best performance in pH value, 5, and optimum time 1 min. Absorption spectra have clearly confirmed the static type fluorescence enhancement mechanism of GO-CD-HQ. Under the optimal conditions, the detection limit of it and linear concentration range for Pb2+ ions were obtained as 3.72 × 10-5 M and (5-60) × 10-5 M, respectively. Additionally, the developed assay exhibited logic gate behavior with Pb2+ ions and vitamin C as a masking agent for cited ions.

Electrospun composite nanofibers as novel high-performance and visible-light photocatalysts for removal of environmental pollutants: A review.

Environmental pollution caused by industries and human manipulations is coming a serious global challenge. On the other hand, the world is facing an energy crisis caused by population growth. Designing solar-driven photocatalysts which are inspired by the photosynthesis of plant leaves is a fantastic solution to use solar energy as green, available, and unlimited energy containing ∼50% visible light for the removal of environmental pollutants. The polymeric and non-polymeric-based electrospun composite nanofibers (NFs) are as innovative photocatalytic candidates which increase photocatalytic activity and transition from UV light to visible light and overcome the aggregation, photocorrosion, toxicity, and hard recycling and separation of the nanosized powder form of photocatalysts. The composite NFs are fabricated easily by either embedding the photocatalytic agents into the NFs during electrospinning or via their decorating on the surface of NFs post-electrospinning. Polyacrylonitrile-based, tungsten trioxide-based, zinc oxide-based, and titanium dioxide-based composite NFs were revealed as the most reported composite NFs. All the lately investigated electrospun composite NFs indicated long-term stability, high photocatalytic efficiency (∼> 80%) within a short time of light radiation (10-430 min), and high stability after several cycles of use. They were applied in various applications including degradation of dyes/antibiotics, water splitting, wastewater treatment, antibacterial usage, etc. The photogenerated species especially holes, O2∙-, and .OH were mostly responsible for the photocatalytic mechanism and pathway. The electrospun composite NFs have the potential to use in large-scale productions in condition that their thickness and recycling conditions are optimized, and their toxicity and detaching are resolved.

Molecular docking and optical sensor studies based on 2,4-diamino pyrimidine-5-carbonitriles for detection of Hg2.

An organic chemical sensor based on pyrimidine was successfully produced through the green reaction between aromatic aldehyde, malononitrile, and guanidine carbonate using SBA-Pr-SO3H. This fluorescence intensity of chemosensor (2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile) decreases by the addition of Hg2+ and its detection limit is about 14.89 × 10-5 M, in fact, through the green synthesis, the ligand was yielded to detect Hg2+ and the importance of ligand was considered in docking studies. The molecular docking of 2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile compound has been done with the protein selective estrogen receptor 5ACC complexed with (Azd9496), Human Anaplastic Lymphoma Kinase Pdb; 2xp2 complex with crizotinib (PF-02341066) and human wee1 kinase Pdb; 5vc3 complexed with bosutinib. The ligands 2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile generate very good docking results with the protein Pdb; 2xp2, which is responsible for effective tumor growth inhibition.

Ultrasound-assisted synthesis of heterocyclic compounds.

In this review, we tried to underscore the synthesis of the heterocyclic compounds under assisted ultrasonic irradiation. The ultrasonic irradiation has been applied for medicinal chemistry and drug discovery process since it dramatically reduces reaction times, from days or hours to minutes. Also, ultrasonic irradiation provides lower cost, excellent yields, greater purity, and simple workups as compared to lower yields, longer reaction times, lesser purity and in the conventional methods. In this review, we have compared synthesis of the heterocyclic compounds under ultrasonic irradiation with other methods.

The molecular diversity scope of 4-hydroxycoumarin in the synthesis of heterocyclic compounds via multicomponent reactions.

4-Hydroxycoumarins are some of the most versatile heterocyclic scaffolds and are frequently applied in the synthesis of various organic compounds. 4-Hydroxycoumarin-based compounds are important among heterocyclic structures due to their biological and pharmaceutical activities. In this study, we provide an overview on the recent applications of 4-hydroxycoumarin in multicomponent reactions for the synthesis of various heterocyclic compounds during the time period of 2015-2018.

Design, synthesis and biological evaluation of benzofuran appended benzothiazepine derivatives as inhibitors of butyrylcholinesterase and antimicrobial agents.

A series of bezofuran appended 1,5-benzothiazepine compounds 7a-v was designed, synthesized and evaluated as cholinesterase inhibitors. The biological assay experiments showed that most of the compounds displayed a clearly selective inhibition for butyrylcholinesterase (BChE), while a weak or no effect towards acetylcholinesterase (AChE) was detected. All analogs exhibited varied BChE inhibitory activity with IC50 value ranging between 1.0 ±â€¯0.01 and 72 ±â€¯2.8 µM when compared with the standard donepezil (IC50, 2.63 ±â€¯0.28 µM). Among the synthesized derivatives, compounds 7l, 7m and 7k exhibited the highest BChE inhibition with IC50 values of 1.0, 1.0 and 1.8 µM, respectively. The results from a Lineweaver-Burk plot indicated a mixed-type inhibition for compound 7l with BChE. In addition, docking studies confirmed the results obtained through in vitro experiments and showed that most potent compounds bind to both the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE active site. The synthesized compounds were also evaluated for their in vitro antibacterial and antifungal activities. The results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms and showed high activity against both gram positive and gram negative bacteria and fungi.

Isatin functionalized nanoporous SBA-15 as a selective fluorescent probe for the detection of Hg(II) in water.

A highly ordered mesoporous silica material functionalized with isatin (SBA-Pr-IS) was designed and synthesized. Characterization techniques including XRD, TGA, BET, SEM, and FT-IR were employed to characterize the pore structure, textural properties, microscopic morphology, and molecular composition of grafted organic moieties of SBA-Pr-IS. The successful attachment of the organic moiety (0.34 mmol g-1) without the SBA-15 structure collapsing after the modification steps was confirmed. Fluorescence characterization of SBA-Pr-IS was examined upon addition of a wide variety of cations in aqueous medium and it showed high sensitivity toward Hg2+ ions. During testing in an ion competition experiment, it was observed that the fluorescence changes of the probe were remarkably specific for Hg2+ ions. Furthermore, a good linearity between the fluorescence intensity of this material and the concentration of Hg2+ ions was constructed with a suitable detection limit of 3.7 × 10-6 M. Finally, the applicability of the proposed method was successfully evaluated for the determination of Hg2+ ions in real samples. Therefore, SBA-Pr-IS can be used as an efficient fluorescence probe for Hg2+ ions. Graphical Abstract A novel organic-inorganic hybrid material was designed and synthesized by functionalization of SBA-15 mesoporous silica material with isatin. The evaluation of the sensing ability of SBA-Pr-IS using fluorescence spectroscopy revealed that the SBA-Pr-IS was a selective fluorescent probe for Hg2+ ion in water in the presence of a wide range of metal cations.

A Fluorescent Sensor for Al(III) and Colorimetric Sensor for Fe(III) and Fe(II) Based on a Novel 8-Hydroxyquinoline Derivative.

A novel 8-hydroxyquinoline-based fluorescent and colorimetric chemosensor was designed, synthesized and fully characterized. The sensor showed high selectivity and sensitivity toward Al(3+) over other tested cations in EtOH/H2O (1:99, v/v) medium. The increase in fluorescence intensity was linearly proportional to the concentration of Al(3+) with a detection limit of 7.38 × 10(-6) M. Moreover, the sensor exhibited an obvious color change from yellow to black in the presence of Fe(2+) and Fe(3+) in EtOH/THF (99:1, v/v) solution. The absorbance changes showed a linear response to iron ions with the detection limits of 4.24 × 10(-7) M and 5.60 × 10(-7) M for Fe(2+) and Fe(3+), respectively. Thus, this chemosensor provides a novel approach for selectively recognition of Al(3+), Fe(3+) and Fe(2+) among environmentally relevant metal ions.

2,6-Bis(2-Benzimidazolyl)Pyridine Fluorescent Red-Shifted Sensor for Recognition of Zinc(II) and a Calorimetric Sensor for Iron Ions.

The ability of 2,6-bis(2-benzimidazolyl)pyridine (bbp) as an optical sensor was studied by fluorescence spectroscopy, colorimetric and UV-visible techniques. The fluorescence spectra of bbp demonstrated a red-shifted upon addition of Zn(2+) ion, whereas rest of the cations did not induce any shift. Selectivity of the sensor was examined toward Zn(2+) in the presence of a wide range of cations, as interfering agents, that showed no disruption in its function. In addition, the pH effect was tested on the fluorescence response of bbp; which showed the efficiency of the sensor in a wide pH range. The limit of detection for Zn(2+) was estimated as 2.1 µM. Furthermore, the colorimetric studies were carried out and the observations showed a color change from colorless to purple by the addition of Fe(2+) ion and from colorless to yellow by the addition of Fe(3+). The UV-visible studies were carried out to confirm the colorimetric observations. The color changes occurred when Fe(2+) and Fe(3+) were added to the sensors solution, respectively. The detection limits were calculated as 2.8 × 10(-7) M and 3.5 × 10(-6) M for Fe(2+) and Fe(3+), respectively. Hence, bbp can be used as a dual mode optical sensor for detection of Zn(2+) by fluorescence and discriminately detection of Fe(2+) and Fe(3+) visually.

A Simple Colorimetric Chemosensor for Naked Eye Detection of Cyanide Ion.

A simple cyanide chemosensor tetranitrile compound 1 was designed and synthesized via an efficient method in the presence of nanoporous SBA-Pr-NH2 as the catalyst. The chemosensor exhibited high selectivity and sensitivity for detecting CN¯ among different anions through a visual color change from light yellow to purple. The results confirmed that the chemosensor 1 causes the color of the solution to change depending on the concentration of CN¯. Linear changes of the optical properties of the sensor as a function of the concentrations of CN¯ was proved. The detection limit of 3.07 × 10(-7) M was calculated for CN¯. A simple paper test strip system for the rapid detection of CN¯ was developed. The TD-DFT calculations were carried out to understand the sensing mechanism.

Chitosan-derived mesoporous N-doped carbon catalyst embedded with NiO for highly selective benzyl alcohol oxidation.

MOF-derived heteroatom-doped mesoporous carbons have gained the significant consideration in heterogenous catalytic reactions because of their multipurpose features. Especially, the high Specific Surface Area (SSA) of these materials provides abundant activated sites for the catalytic reactions, while the mesoporous structure allows for the effective mass transfer, enhancing the overall capability of the catalytic process. Herein, the efficient NiO/CN-T (T referred to the pyrolysis temperature) was prepared by facile pyrolysis of MOF/CS composite (Ni-MOF (74), Chitosan) in the presence of excess amount of starch as the carbon precursor. The NiO/CN-T as heterogenous catalyst has desired SSA varied from 1094 to 491 m2.g-1. The optimized catalyst (NiO/CN-600) possesses the superior catalytic activity toward the oxidation of the BnOHs due to its high SSA (1094 m2.g-1), which can notably rectify the mass transfer proficiency. Additionally, the NiO/CN-600 heterogenous catalyst also represents the acceptable chemical stability. So, it was demonstrated that such an innovative strategy can provide several versatile tunability insights for the preparation of MOF/biopolymer-derived heterogenous catalysts.

Coumarin derivative-functionalized nanoporous silica as an on-off fluorescent sensor for detecting Fe3+ and Hg2+ ions: a circuit logic gate.

A highly efficient fluorescent sensor (S-DAC) was easily created by functionalizing the SBA-15 surface with N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane followed by the covalent attachment of 7-diethylamino 3-acetyl coumarin (DAC). This chemosensor (S-DAC) demonstrates selective and sensitive recognition of Fe3+ and Hg2+ in water-based solutions, with detection limits of 0.28 × 10-9 M and 0.2 × 10-9 M for Hg2+ and Fe3+, respectively. The sensor's fluorescence characteristics were examined in the presence of various metal ions, revealing a decrease in fluorescence intensity upon adding Fe3+ or Hg2+ ions at an emission wavelength of 400 nm. This sensor was also able to detect ferric and mercury ions in spinach and tuna fish. The quenching mechanism of S-DAC was investigated using UV-vis spectroscopy, which confirmed a static-type mechanism for fluorescence quenching. Moreovre, the decrease in fluorescence intensity caused by mercury and ferric ions can be reversed using trisodium citrate dihydrate and EDTA as masking agents, respectively. As a result, a circuit logic gate was designed using Hg2+, Fe3+, trisodium citrate dihydrate, and EDTA as inputs and the quenched fluorescence emission as the output.

Tailored Covalent Organic Framework Platform: From Multistimuli, Targeted Dual Drug Delivery by Architecturally Engineering to Enhance Photothermal Tumor Therapy.

Engineering bulk covalent organic frameworks (COFs) to access specific morphological structures holds paramount significance in boosting their functions in cancer treatment; nevertheless, scant effort has been dedicated to exploring this realm. Herein, silica core-shell templates and multifunctional COF-based reticulated hollow nanospheres (HCOFs) are novelly designed as a versatile nanoplatform to investigate the simultaneous effect of dual-drug chemotherapy and photothermal ablation. Taking advantage of the distinct structural properties of the template, the resulting two-dimensional (2D) HCOF, featuring large internal voids and a peripheral interconnected mesoporous shell, presents intriguing benefits over its bulk counterparts for cancer treatment, including a well-defined morphology, an outstanding drug loading capability (99.6%) attributed to its ultrahigh surface area (2087 m2/g), great crystallinity, improved tumor accumulation, and an adjustable drug release profile. After being loaded with hydrophilic doxorubicin with a remarkable loading capacity, the obtained drug-loaded HCOFs were coated with gold nanoparticles (Au NPs) to confer them with three properties, including pore entrance blockage, active-targeting capability, and improved biocompatibility via secondary modification, besides high near infrared (NIR) absorption for efficient photothermal hyperthermia cancer suppression. The resultant structure was functionalized with mono-6-thio-ß-cyclodextrin (ß-CD) as a second pocket to load docetaxel as the hydrophobic anticancer agent (combination index = 0.33). The dual-drug-loaded HCOF displayed both pH- and near-infrared-responsive on-demand drug release. In vitro and in vivo evaluations unveiled the prominent synergistic performance of coloaded HCOF in cancer elimination upon NIR light irradiation. This work opens up a new avenue for exciting applications of structurally engineered HCOFs as hydrophobic/hydrophilic drug carriers as well as multimodal treatment agents.

Recent advances in covalent organic frameworks (COFs) for wound healing and antimicrobial applications.

Covalent organic frameworks (COFs) are crystal-like organic structures such as cartography buildings prepared from appropriately pre-designed construction block precursors. Moreover, after the expansion of the first COF in 2005, numerous researchers have been developing different materials for versatile applications such as sensing/imaging, cancer theranostics, drug delivery, tissue engineering, wound healing, and antimicrobials. COFs have harmonious pore size, enduring porosity, thermal stability, and low density. In addition, a wide variety of functional groups could be implanted during their construction to provide desired constituents, including antibodies and enzymes. The reticular organic frameworks comprising porous hybrid materials connected via a covalent bond have been studied for improving wound healing and dressing applications due to their long-standing antibacterial properties. Several COF-based systems have been planned for controlled drug delivery with wound healing purposes, targeting drugs to efficiently inhibit the growth of pathogenic microorganisms at the wound spot. In addition, COFs can be deployed for combinational therapy using photodynamic and photothermal antibacterial therapy along with drug delivery for healing chronic wounds and bacterial infections. Herein, the most recent advancements pertaining to the applications of COF-based systems against bacterial infections and for wound healing are considered, concentrating on challenges and future guidelines.