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This work developed a novel sustainable adsorbent (PF-Aq) prepared by the amino-functionalization of palm oil fibers (PF). XPS, SEM/EDS, TGA/DSC, and FT-IR techniques proved the successful functionalization of the PF with the amino group. The PF-Aq adsorbent presents a high adsorption capacity for phosphate and Cr(VI) ions. Adsorption kinetics of the ions onto the PF-Aq followed the general-order models, with 240- and 300-min equilibrium times for phosphate and Cr(VI), respectively. The Freundlich equilibrium model can explain the adsorption of phosphate and Cr(VI) on the PF-Aq. Besides, the maximum adsorption capacities were 151.07 mg g -1 for phosphate and 206.08 mg g -1 for Cr(VI). The best pH for the adsorption of both ions on PF-Aq was 4.0. Interestingly, adsorption was exothermic for phosphate and endothermic for Cr(VI). The adsorption capacities were reduced by 16% for phosphate and 10% for Cr(VI) after 5 adsorption-desorption cycles, demonstrating the good recyclability of the PF-Aq. It can be concluded that PF-Aq is a relevant adsorbent to uptake phosphate and Cr(VI) from water due to its high adsorption capacity, low cost, recyclability, availability, and fast kinetics. Finally, the excellent adsorption potential results from inserting amino groups in the PF, allowing electrostatic interactions between adsorbent and adsorbate., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Due to their prevalence in the lithosphere and their high capability of sorbing pollutants, smectite clays play a foreground role in environmental pollution studies, waste management, and soil science. In complementarity with existing approaches at the molecular or macroscopic scales, real microstructures have been employed to investigate ionic transport by diffusion through montmorillonite and water-saturated Wyoming bentonite at intermediate scales ranging between the nanometer and the micrometer. The coupled solute transport and electrostatic phenomena investigated at the nanopore scale are upscaled using the homogenization of porous media approach. Homogenization computations rely on a hierarchical description of bentonite that acknowledges the existence of pores networks at different scales. At the scale of montmorillonite layers, digitized TEM images have been employed to simulate the diffusion of ionic solutes by considering electrostatic interactions in the vicinity of the negatively charged clay platelets' surface. Finite element microstructures are created after extraction of the contours of the layers using dedicated image processing algorithms. Local electric potential distribution, anion exclusion, and cation inclusion are displayed by ion distribution maps. The effective diffusion tensor and the transport equation obtained through volume averaging are then used to simulate diffusion at the scale of a Wyoming bentonite sample composed of clay gels of variable density, solid grains, and micropores. Qualitative comparisons were made with existing diffusion data, and a particular attention is given to the anisotropy of the diffusion tensors at both the mesoscopic and macroscopic scales., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This review provides an in-depth examination of recent progress in the development of chemosensors, with a particular emphasis on colorimetric and fluorescent probes. It systematically explores various sensing mechanisms, including metal-to-ligand charge transfer (MLCT), ligand-to-metal charge transfer (LMCT), photoinduced electron transfer (PET), intramolecular charge transfer (ICT), and fluorescence resonance energy transfer (FRET), and elucidates the mechanism of action for cation and anion chemosensors. Special attention is given to phenothiazine-based fluorescence probes, highlighting their exceptional sensitivity and rapid detection abilities for a broad spectrum of analytes, including cations, anions, and small molecules. Phenothiazine chemosensors have emerged as versatile tools widely employed in a multitude of applications, spanning environmental and biomedical fields. Furthermore, it addresses existing challenges and offers insights into future research directions, aiming to facilitate the continued advancement of phenothiazine-based fluorescent probes., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this work, a novel magnetic covalent organic framework (COF (TpPa-NH 2 ) @ Fe 3 O 4 ) was prepared via two step by simple solvent method for the extraction of anionic azo dye residues in food. The as-prepared COF (TpPa-NH 2 ) @ Fe 3 O 4 nanocomposite was characterised by scanning electron microscope, transmission electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. Before high-performance liquid chromatography with ultraviolet detection (HPLC-UV) determination, it was used as magnetic adsorbent for magnetic solid-phase extraction (MSPE) to extract and pre-concentrate three anionic azo dyes in carbonated beverage samples. The several key extraction and desorption parameters affecting the extraction recovery rate were investigated, including extraction time, pH of the solution, amount of material, adsorption time, elution solvent, pH of elution solvent, type of elution solvent, elution volume and elution time. Under optimised conditions, this method has good linearity between 5 and 500 μg L -1 (correlation coefficient > 0.9986). The limit of detection was 2.3-3.4 μg L -1 . The recoveries of the samples were between 87.5 and 96.9%, and the relative standard deviation lower than 4.6%. The developed method has broad application prospects for the analysis of anionic azo dyes in carbonated beverages., (© 2024. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry 2024.)

The development of bifunctional hybrid materials based on natural clays and layered double hydroxide (LDH) and their application on the simultaneous adsorption of Cd(II) and As(V) was investigated in this work. Two different synthesis routes, in situ and assembly, were employed to obtain the hybrid materials. Three types of natural clays, namely bentonite (B), halloysite (H), and sepiolite (S), were used in the study. These clays are characterized by a laminar, tubular, and fibrous structural arrangement, respectively. The physicochemical characterization results indicate that the hybrid materials were formed through interactions between the Al-OH and Si-OH groups present in the natural clays, and the Mg-OH and Al-OH groups present in the LDH for both synthesis routes. However, the "in situ" route yields a more homogenous material because the LDH formation is performed on the natural clay surface. The hybrid materials showed an anion and cation exchange capacity up to 200.7 meq/100 g and an isoelectric point near 7. The arrangement of natural clay has no impact on the properties of hybrid material but influences the adsorption capacity. The adsorption of Cd(II) onto hybrid materials was enhanced in comparison with natural clays, obtaining adsorption capacities of 80, 74, 65, and 30 mg/g for 15:1 (LDH:H) INSITU , 1:1 (LDH:S) INSITU , 1:1 (LDH:B) INSITU , and 1:1 (LDH:H) INSITU , respectively. The adsorption capacities of hybrid materials to adsorb As(V) were between 20 and 60 μg/g. The 15:1 (LDH:H) INSITU sample showed the best adsorption capacity being ten folds greater than halloysite and LDH. In all cases, the hybrid materials showed a synergistic effect for Cd(II) and As(V) adsorption. The adsorption study of Cd(II) onto hybrid materials showed that the primary adsorption mechanism is cation exchange between the interlayer cations in natural clay and Cd(II) in the aqueous solution. The adsorption of As(V) showed that the adsorption mechanism is attributed to anion exchange between CO 2 3- in the interlayer space of LDH and H 2 ASO 4 - in the solution. The simultaneous adsorption of As (V) and Cd (II) shows that, during the As(V) adsorption, there is no competition by the adsorption sites. Still, the adsorption capacity towards Cd(II) was enhanced 1.2-folds. This study ultimately revealed that the arrangement of clay has a significant influence on the adsorption capacity of the hybrid material. This can be attributed to the similar morphology between the hybrid material and natural clays, as well as the important diffusion effects observed in the system., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this study, chitosan nanoparticles (ChNs) were used as an adsorbent for single and simultaneous uptake of cationic (methylene blue (MB)) and anionic (methyl orange (MO)) dyes. ChNs were prepared based on the ionic gelation method using sodium tripolyphosphate (TPP) and characterized by zetasizer, FTIR, BET, SEM, XRD, and pH PZC . The studied parameters that affect removal efficiency included pH, time, and dyes' concentration. The results showed that in single-adsorption mode, the removal of MB is better in alkaline pH, contrary to MO uptake which presents higher removal efficiency in acidic media. The simultaneous removal of MB and MO from the mixture solution by ChNs could be achieved under neutral conditions. The adsorption kinetic results showed that adsorption of MB and MO for both single-adsorption and binary adsorption systems comply with the pseudo-second-order model. Langmuir, Freundlich, and Redlich-Peterson isotherms were used for the mathematical description of single-adsorption equilibrium, while non-modified Langmuir and extended Freundlich isotherms were used to fit the co-adsorption equilibrium results. The maximum adsorption capacities of MB and MO in a single dye adsorption system were 315.01 and 257.05 mg/g for MB and MO, respectively. On the other hand, and for binary adsorption system, the adsorption capacities were 49.05 and 137.03 mg/g, respectively. The adsorption capacity of MB decreases in solution containing MO and vice versa, suggesting an antagonistic behavior of MB and MO on ChNs. Overall, ChNs could be a candidate for single and binary removal of MB and MO in dye-containing wastewater., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Considering the serious health effects of fluoride contamination, an environment friendly bioadsorbent was derived from wattle humus for fluoride removal by conventional thermal activation process. Analytical characterizations revealed that heterogeneous morphological textured wattle humus enabled remarkable adsorption capacity. XPS analysis substantiated that fluoride had been successfully adsorbed on to the carbonized wattle humus surface through chemisorption. Fluoride adsorption efficiency was systematically rationalized via batch adsorption studies. Experiments were performed at different initial fluoride concentration and scrutinized the impact of contact time (10-120 min), adsorbent dosage (0.5-2.5 g), pH (2.0-9.0), and interfering co-existing ions (SO 4 2- , NO 3 - , Cl - , and HCO 3 - ) on fluoride removal. Even at different adsorbate dosage (2-10 mg/L), 98% fluoride removal efficiency was achieved under pH > 6. The competitive anions do not interfere the wattle humus fluoride adsorption capacity. Moreover, the adsorption isotherms and kinetics studies inferred that monolayer and multilayer adsorption behavior by wattle humus leads to noticeable fluoride adsorption. Adsorbent regeneration test affirms that regenerated adsorbent found higher (>95%) fluoride removal efficiency even at five recycle runs., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Surface -functionalised silica networks are advanced adsorbents. They have been given much attention for treating wastewater using the adsorption technique due to the silanol reactivity, resulting in strong binding affinities towards many pollutants. This review discusses the removal of anionic azo dyes utilising various functional groups such as amines, surfactants, polymers, macrocyclic, and other chelating groups functionalised on silica's surface. This review also reveals the steadily increasing interest in surface-functionalised silicas as adsorbents, emphasising the scholarly advancements in this field as a platform for future research. For that, adsorption capacities with different experimental conditions have been compared. The possible adsorption mechanisms, rate-limiting step, and factors affecting the anionic azo dye adsorption process have been comprehensively discussed. This review discloses that adsorbent characteristics such as porosity and functional groups, besides structural properties of an anionic azo dye, significantly affect adsorption. The adsorption process followed the Langmuir isotherm and pseudo-second-order models, with a predominantly spontaneous and endothermic nature. Multiple interactions, including electrostatic interaction, π-π interactions, and hydrogen bonding, are observed between dyes and functionalised silicas, indicating the adsorption process's complexity. Regeneration and cost-economic analysis are also presented to provide a roadmap for sustainable improvements. Chemical and biological regeneration techniques restore > 80% of the spent functionalised silicas. There is a significant opportunity to improve their efficiencies and regenerability, resulting in surface-functionalised silicas being used commercially instead of only in the laboratory. Finally, future research has been proposed by identifying current research gaps, particularly concerning the application of functionalised silicas in wastewater treatment., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The mechanism of host-guest interaction of receptors towards fluoride ion has been investigated using computational methods. To distinguish the effect of aromaticity in host-guest interaction, we investigated unsubstituted (ATSC) and phenyl-substituted (APTSC) anthracene thiosemicarbazones towards different ions. In the ground state of receptor-fluoride complex, the added fluoride ion made hydrogen bond through N - H … F … H - N, whereas the intramolecular hydrogen bonding was through F - H … N in the excited state of receptor-fluoride complex. Experimental absorption and emission spectra were well reproduced by the calculated vertical excitation energies. The transition state (TS) calculations were performed to understand the thermodynamic features and mechanism of host-guest interaction. The natural bond orbital analyses show that the second perturbation energy for donor-acceptor interaction of F - with hydrogen is more than 300 kcal/mol -1 at the excited state of receptor-fluoride complex, which indicates the strong single bond between fluoride and hydrogen atom. The PES scan confirms that deprotonation took place at the excited state of receptor-fluoride complex. The results indicate the excited-state proton transfer (ESPT) process from N-H group nearby the anthracene moiety. The APTSC is a better chemosensor than ATSC. This infers that the aromaticity will increase the efficiency of fluorescence receptor towards fluoride ion. A schematic representation of sensing mode of anthracene-based thiosemicarbazones toward fluoride ion. The fluoride ion first makes a hydrogen bond with NH proton nearby anthracene moiety. The excited state proton transfer mechanism was confirmed by PES and NBO studies., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this work, we have theoretically studied the dicationic ionic liquids (DILs) constructed from geminal methylimidazolium dication with varying amino acid anions and spacers using density functional theory. Amino acid-based DILs form via strong C-H···O hydrogen bonds. These hydrogen bonds have a significant role in stabilizing the DILs. The higher cation-anion interaction energy in the order of covalent bond energy and liquid density of DILs imply higher thermal stability than their mono analogues. The C-H stretching frequencies are above 3100 cm -1 in all complexes and form a signature for DILs. Interestingly, aliphatic and aromatic amino acid anions show similar molecular properties. Overall, the DILs formed from amino acids exhibit high stability and large surface tension and are chemically non-toxic; hence, they can replace inorganic DILs.

A catechol-functionalized phenazine imidazole (PD) was tailored with 2,3-diaminophenazine and 3,4-dihydroxy benzaldehyde, and it served as a hybrid acceptor for capturing HSO 4 - anions. The selectivity and sensitivity of the PD receptor for anion sensing were studied. It was found that the PD receptor could not only display a preferable sensitivity to HSO 4 - ions with a "turn-off" fluorescence response, but also have a strong anti-interference ability toward other common anions, especially basic anions such as CH 3 COO - , HPO 4 2- , and H 2 PO 4 - . The anion recognition mechanism of PD towards HSO 4 - is based on multiple hydrogen bond interactions. Finally, the strips for anion detection were prepared, which were verified to be a convenient and high-efficiency test kit for detecting HSO 4 - ions with the naked eye.

NMR spectroscopy is commonly used to infer site-specific acid dissociation constants (pK a ) since the chemical shift is sensitive to the protonation state. Methods that probe atoms nearest to the functional groups involved in acid/base chemistry are the most sensitive for determining the protonation state. In this work, we describe a magic-angle-spinning (MAS) solid-state NMR approach to measure chemical shifts on the side chain of the anionic residues aspartate and glutamate. This method involves a combination of double quantum spectroscopy in the indirect dimension and REDOR dephasing to provide a sensitive and resolved view of these amino acid residues that are commonly involved in enzyme catalysis and membrane protein transport. To demonstrate the applicability of the approach, we carried out measurements using a microcrystalline soluble protein (ubiquitin) and a membrane protein embedded in lipid bilayers (EmrE). Overall, the resolution available from the double quantum dimension and confidence in identification of aspartate and glutamate residues from the REDOR filter make this method the most convenient for characterizing protonation states and deriving pK a values using MAS solid-state NMR.

Industrial effluents are one of the foremost concerns relating to the anthropogenic environmental pollution. The effluents from the tanning and textile industries in Dhaka, Bangladesh, were characterized chemically and physicochemically with multivariate statistical techniques. The concentrations of heavy metals viz., Pb, Cd, Cr, Mn, Fe, Ni, Cu, and Zn were determined by atomic absorption spectrometer while concentrations of anions viz., F - , Cl - , NO 2 - , NO 3 - , and SO 4 2- were measured by ion chromatograph. The physicochemical parameters viz., temperature, pH, electrical conductivity (EC), salinity, turbidity, dissolved oxygen (DO), and biological oxygen demand (BOD) were measured by a multiparameter meter while total suspended solids (TSS) and total dissolved solids (TDS) were measured gravimetrically. This study showed that effluents from both industries demonstrated high levels of TSS, TDS, EC, and heavy metals. Tannery effluents have lower pH and DO, and higher BOD, Cl - , SO 4 2- , and Cr concentrations while textile dyeing effluents have higher pH, NO 2 - , and NO 3 - concentrations, compared to the standard limits promulgated by the Bangladesh government. Multivariate statistical techniques such as cluster analysis and principal component analysis along with the correlation matrices showed significant association among the measured parameters and identified pollution sources as well as effluent types in the study area which could be linked to the processes used in textile dying and tanning industries. This study will be useful for identifying pollutants emanating from the two industries and will guide future industrial aquatic studies where multiple industrial runoffs are concerned.

A magnesia-pullulan (MgOP) composite has been developed to remove phosphate from a synthetic solution. In the present study, the removal of phosphate by MgOP was evaluated in both a batch and dynamic system. The batch experiments investigated the initial pH effect on the phosphate removal efficiency from pH 3 to 12 and the effect of co-existing anions. In addition, the adsorption isotherms, thermodynamics, and kinetics were also investigated. The results from the batch experiments indicate that MgOP has encouraging performance for the adsorption of phosphate, while the initial pH value (3-12) had a negligible influence on the phosphate removal efficiency. Analysis of the adsorption thermodynamics demonstrated that the phosphate removal process was endothermic and spontaneous. Investigations into the dynamics of the phosphate removal process were carried out using a fixed bed of MgOP, and the resulting breakthrough curves were used to describe the column phosphate adsorption process at various bed masses, volumetric flow rates, influent phosphate concentrations, reaction temperatures, and inlet pH values. The results suggest that the adsorption of phosphate on MgOP was improved using an increased bed mass, while the reaction temperature did not significantly affect the performance of the MgOP bed during the phosphate removal process. Furthermore, higher influent phosphate concentrations were beneficial towards increasing the column adsorption capacity for phosphate. Several mathematic models, including the Adams-Bohart, Wolboska, Yoon-Nelson, and Thomas models, were employed to fit the fixed-bed data. In addition, the effluent concentration of magnesium ions was measured and the regeneration of MgOP investigated.

A raw illite-smectite mixed-layered clay (RI/S) was ground for preparing nano-sized I/S clay (NI/S) and subsequently amino-functionalized via grafting of 3-aminopropyltrithoxysilane (APTES) (NH 2 -RI/S and NH 2 -NI/S, respectively). The samples were characterized by particle size analysis, specific surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and 29 Si nuclear magnetic resonance ( 29 Si NMR). Compared to RI/S, NI/S has a narrow particle size distribution and appears in a platelet-like morphology due to the disintegration/exfoliation of RI/S after grinding. Based on the 29 Si NMR spectra, the appearances of tri-silicate units indicate the chemically grafting of APTES molecules on NH 2 -RI/S and NH 2 -NI/S, respectively. NH 2 -NI/S can adsorb greater amounts of Pb(II) cations and Cr(VI) anions rather than NH 2 -RI/S since NH 2 -NI/S grafts more amounts of amine groups (-NH 2 ). The isotherm data for adsorption of Pb(II) cations and Cr(VI) anions can be described by the Langmuir model at different temperatures (i.e., 10 °C, 30 °C, and 50 °C), respectively. The maximum adsorption amounts of Pb(II) cations and Cr(VI) anions onto NH 2 -NI/S calculated by the Langmuir isotherm model are 131.23 mg/g and 36.91 mg/g at 50 °C, respectively. The adsorptions of Pb(II) cations and Cr(VI) anions onto NH 2 -NI/S involve in the surface complexation of NI/S and amine groups.

Anion binding C α NN motif is found in functionally important regions of protein structures. This motif based only on backbone atoms from three adjacent residues, recognizes free sulphate or phosphate ion as well as phosphate groups in nucleotides and in a variety of cofactors. The mode of anion recognition and microscopic picture of binding interaction remains unclear. Here we perform self-consistent quantum chemical calculations considering sulphate and phosphate bound C α NN motif fragments from crystal structures of functional proteins in order to figure out microscopic basis of anion recognition. Our calculations indicate that stability and preference of the anion in the motif depends on the sequence of the motif. The stabilization energy is larger in case of polar residue containing motif fragment. Nitrogen atom of the polar residue of motif mainly participates in the coordination at the lowest energy levels. Anion replacement decreases stabilization energy along with coordination between motif atoms and oxygen atoms of anion shifted to higher energies, suggesting preference of the motif residues to specific anion. Our analysis may be helpful to understand microscopic basis of interaction between proteins and ionic species.

Textile dyes pose a significant challenge for water pollution due to the poor degradability of their complex aromatic structures (e.g., RR-120 and RBB-150). In order to minimize the harmful effects of RR-120 and RBB-150, the capacity of MgAl-layered double hydroxide for removing of these contaminants was studied herein. Batch adsorption experiments were conducted to investigate the effect of various operating parameters, such as solution pH, contact time, dye concentration, and temperature in order to provide optimal conditions for removal. Structural and morphological analyses were used to highlight the assembly and/or interaction LDH-dye. The state of equilibrium of RR-120 and RBB-150 adsorption was pH- and temperature-dependent and followed the pseudo-second-order rate model. Also, the equilibrium adsorption data of both dyes were found to adopt the Langmuir type isotherm model, which assumes a monolayer arrangement in LDH-dye. Furthermore, the effects of four major coexisting and competing mono- and divalent interlayer anions, such as NO 3 - , Cl - , CO 3 2- , and SO 4 2- , on the uptakes of RR-120 and RBB-150 were studied and the results showed that NO 3 - anions had insignificant effect on the uptakes of RR-120 and RBB-150 by MgAl. An equivalent study on the presence of both dyes in competitive trial adsorption/desorption from binary aqueous solution was investigated. And finally, the reuse operation of recovered material after dye adsorption was tested in up to 5 cycles of recyclability.

In this study, the effect of Fe 3+ , Fe 2+ , and Mn 2+ dose, solution pH, reaction temperature, background water matrix (i.e., inorganic anions, cations, and natural organic matters (NOM)), and the kinetics and mechanism for the reaction system of Fe(VI)/Fe 3+ , Fe(VI)/Fe 2+ , and Fe(VI)/Mn 2+ were investigated systematically. Traces of Fe 3+ , Fe 2+ , and Mn 2+ promoted the DCF removal by Fe(VI) significantly. The pseudo-first-order rate constant (k obs ) of DCF increased with decreasing pH (9-6) and increasing temperature (10-30 °C) due to the gradually reduced stability and enhanced reactivity of Fe(VI). Cu 2+ and Zn 2+ ions evidently improved the DCF removal, while CO 3 2- restrained it. Besides, SO 4 2- , Cl - , NO 3 - , Mg 2+ , and Ca 2+ almost had no influence on the degradation of DCF by Fe(VI)/Fe 3+ , Fe(VI)/Fe 2+ , and Fe(VI)/Mn 2+ within the tested concentration. The addition of 5 or 20 mg L -1 NOM decreased the removal efficiency of DCF. Moreover, Fe 2 O 3 and Fe(OH) 3 , the by-products of Fe(VI), slightly inhibited the DCF removal, while α-FeOOH, another by-product of Fe(VI), showed no influence at pH 7. In addition, MnO 2 and MnO 4 - , the by-products of Mn 2+ , enhanced the DCF degradation due to catalysis and superposition of oxidation capacity, respectively. This study indicates that Fe 3+ and Fe 2+ promoted the DCF removal mainly via the self-catalysis for Fe(VI), and meanwhile, the catalysis of Mn 2+ and the effect of its by-products (i.e., MnO 2 and MnO 4 - ) contributed synchronously for DCF degradation. Graphical abstract ᅟ.

A detailed account on the photophysics of 3-hydroxyflavone (3HF) in 27 organic solvents is reported. Dual fluorescence of neutral 3HF was observed in protic, polar, and weakly polar solvents, endowed with sufficiently high hydrogen bond accepting and/or donating capabilities. Ground-state solvent-induced 3HF deprotonation was reported in 14 cases. 3HF anion photophysics was investigated, and the deprotonation constant Kdep calculated. Previously reported models (based on solute-solvent intermolecular hydrogen bonds) to explain solvent effects on Excited-State Intramolecular Proton Transfer (ESIPT) and on solvent-induced deprotonation have been re-examined and improved in order to rationalize the observed photophysical behaviour in all the studied solvents. Hydrogen bond donor acidity and hydrogen bond acceptor basicity are shown to be key parameters. The results are discussed in the framework of the use of 3HF as an environment-sensitive fluorescent sensor in several research fields, and as a model system in the study of ESIPT reactions. Solvent effects on 3HF reactivity are also discussed, as the role of the surrounding media on the chemistry of flavonols is an emerging topic in natural product research.

To obtain an economical and effective adsorbent for fluoride removal, lanthanum-loaded pomelo peel biochar (PPBC-La) was synthesized using a facile approach. The batch adsorption experiments were investigated to determine adsorbent performance. The PPBC-La and its pristine biochar (PPBC) were characterized by scanning electronic microscopy (SEM), zeta potential, Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) methods. Experimental results showed that the adsorption data were described well by the pseudo-second-order kinetic and Freundlich isotherm models. The maximum fluoride adsorption capacity for PPBC-La was found to be 19.86 mg/g at 25 °C and pH 6.5. The PPBC-La worked well at pH 2.4-9.6 and carried positive charge at pH < 5.8. The presence of SO 4 2- , Cl - , and NO 3 - had a slight effect on fluoride uptake except HCO 3 - and PO 4 3- . The real groundwater study testified that 9.8 mg/L of fluoride was removed effectively at 1.0 g/L of dosage and pH 5.2. The regeneration results revealed that the PPBC-La had a good reusability. According to FTIR, XPS analysis and the anion exchange experiment, anions (NO 3 - and OH - ) exchange with fluoride ions was mainly responsible for fluoride adsorption.

In this study, the FPA90-Cl resin was magnetized with supported Fe 3 O 4 particles using a chemical co-precipitation method and its removal performance of bromate and coexisting precursors was explored. The magnetized FPA90-Cl resin was structurally characterized by SEM, FT-IR, and XRD. The effects of the initial concentrations, temperature, and resin dosage on bromate and bromide ion removal in drinking water were investigated using batch experiments. The magnetized FPA90-Cl resin exhibited a high removal efficiency for bromate and bromide ions at three initial concentrations, and the residual bromate concentrations were under the maximum contaminant level (MCL) of 10 μg L -1 after 80 min. The adsorption data of bromate and bromide ion could be well described by a pseudo-first-order kinetic model (R 2  ˃ 0.98). The bromate removal alone was further studied by varying the initial solution pH, temperature, and competitive anions. The results showed that the magnetized FPA90-Cl resin could be used over a wide pH range (4.0-9.0). The maximum sorption capacity of the magnetized FPA90-Cl resin for bromate reached 132.83 mg g -1 at 298 K. The Freundlich and Redlich-Peterson isotherm models fit the bromate adsorption equilibrium better (R 2  ˃ 0.99) than the Langmuir isotherm model (R 2  ˃ 0.98). The thermodynamic analysis showed that the bromate adsorption process was endothermic. The negative ΔG and positive ΔS indicated that the process was spontaneous and that randomness increased after adsorption, respectively. The competition of coexisting anions with bromate was in the order of SO 4 2-  > CO 3 2-  > Cl -  > NO 3 -  > HCO 3 -  > PO 4 3- . Additionally, the magnetized FPA90-Cl resin could maintain a high bromate and bromide ion adsorption capacity after five cycles of regeneration by a 0.1 M NaCl solution. Graphical abstract ᅟ.

New benzimidazole and benzothiazole derivatives (S1-S3) derived from thiophene-2,5-dicarboxaldehyde and 5,5'-bipyridyldicarboxaldehyde with NSN/SSS/NN binding sites were tested against various cations and anions. S3 showed selectivity toward copper(ii) ions among other cations under consideration with the colour change to pale yellow from colourless under aqueous medium. In the cases of S1 and S2, no colour change was observed. S1 alone showed selective fluorescence turn on for Cr(iii) ions among other cations. S1 showed sensitivity towards Cr(iii) with fluorescence change with bathochromic shift. The prominent fluorescence change of S1 with Cr(iii) ions was applied to live cell imaging of HeLa cells.

Metallurgical slag was used for the simultaneous removal of high concentrations of arsenite and arsenate from laboratory solutions and severely contaminated groundwater. Apart from demonstrating the high efficiency of arsenic removal in presence of competing species, the work aims to explore the physicochemical mechanisms of the process by means of microscopy observation and a detailed statistical analysis of existing kinetic and isotherm equations. Fitting was performed by non-linear least squares using weighted residuals; ANOVA and bootstrap methods were used to compare the models. Literature suggests that the metal oxides in the slag are efficient adsorbents of As(III) and (V). However, the low surface area of the slag precludes adsorption; SEM observation provide evidence of a mechanism of co-precipitation of lixiviated cations with contaminant anions. The reaction kinetics provide essential information on the interaction between the contaminants, particularly on the common ion effect in groundwater. The Fritz-Schlünder isotherm allows modelling the saturation effect at low slag doses. The efficiency of the process is demonstrated by an arsenic removal of 99% in groundwater using 4-g slag/L, resulting in an effluent with 0.01 mg As/L, which is below Mexican and international standards for drinking water.

Protein stability is known to be influenced by the presence of Hofmeister active ions in the solution. In addition to direct ion-protein interactions, this influence manifests through the local alterations of the interfacial water structure induced by the anions and cations present in this region. In our earlier works it was pointed out that the effects of Hofmeister active salts on the stability of Trp-cage miniprotein can be modeled qualitatively using non-polarizable force fields. These simulations reproduced the structure-stabilization and structure-destabilization effects of selected kosmotropic and chaotropic salts, respectively. In the present study we use the same model system to elucidate atomic processes behind the chaotropic destabilization and kosmotropic stabilization of the miniprotein. We focus on changes of the local hydration environment of the miniprotein upon addition of NaClO 4 and NaF salts to the solution. The process is separated into two parts. In the first, 'promotion' phase, the protein structure is fixed, and the local hydration properties induced by the simultaneous presence of protein and ions are investigated, with a special focus on the interaction of Hofmeister active anions with the charged and polar sites. In the second, 'rearrangement' phase we follow changes of the hydration of ions and the protein, accompanying the conformational relaxation of the protein. We identify significant factors of an enthalpic and entropic nature behind the ion-induced free energy changes of the protein-water system, and also propose a possible atomic mechanism consistent with the Collins's rule, for the chaotropic destabilization and kosmotropic stabilization of protein conformation.

Two novel fluorescent probes based on triphenylamine (TPC) and phenanthro(9,10-d-imidazole) (PITP) have been synthesized and studied as cyanide selective indicators in aqueous media. Complete colour bleaching was observed due to the nucleophilic addition of cyanide to the 2-vinylmalononitrile of TPC, which results in the disruption of the extended conjugation and turns off the intramolecular charge transfer (ICT) process. Furthermore, a visible color change was observed with a large Stokes shift (108 nm) upon the addition of cyanide anions to PITP, due to the formation of hydrogen bonding between the CN - anion and -NH of PITP, which increased the electron density on the donor moiety and induced strong ICT.

The current problem of excess impurities in industrial phosphoric acid (IPA) 54 % P2O5 makes phosphates industries look toward low-cost but efficient adsorbents. In the present study, iron-oxide-modified bentonite (Fe-PILB) was prepared and investigated as a possible adsorbent for the removal of organic matter (OM) like humic acid (HA), chromium (Cr(III)), and zinc (Zn(II)) from IPA aqueous solutions. These adsorbents were characterized using XRD, TEM, and BET. The adsorption of impurities is well described by the pseudo-second-order model. The results indicate that Fe-PILB has a good ability to resist co-existing anions and the low-pH condition of IPA and owns a relatively high-removal capacity of 80.42 and 25 % for OM, Cr(III), and Zn(II). The mechanism of adsorption may be described by the ligand and ion exchange that happened on the active sites. The selected order of adsorption OM > Cr(3+) > Zn(2+) showed the importance of the competitive phenomenon onto bentonite materials' pore adsorption. For the adsorption of OM at the low pH of IPA, H-bond complexation was the dominant mechanism. From the adsorption of heavy metals and OM complex compounds contained in IPA 54 % on Fe-PILB, the bridging of humic acid between bentonite and heavy metals (Zn(II) or Cr(III)) is proposed as the dominant adsorption mechanism (bentonite-HA-Me). Overall, the results obtained in this study indicate Fe-pillared bentonite possesses a potential for the practical application of impurity (OM, Zn(II), and Cr(III)) removal from IPA aqueous solutions.

We analyzed the potential influence of anion-π interactions on the stability of complexes of proteins and halogen-containing non-natural amino acids. Anion-π interactions are distance and orientation dependent and our ab initio calculations showed that their energy can be lower than -8 kcal mol(-1), while most of their interaction energies lie in the range from -1 to -4 kcal mol(-1). About 20 % of these interactions were found to be repulsive. We have observed that Tyr has the highest occurrence among the aromatic residues involved in anion-π interactions, while His made the least contribution. Furthermore, our study showed that 67 % of total interactions in the dataset are multiple anion-π interactions. Most of the amino acid residues involved in anion-π interactions tend to be buried in the solvent-excluded environment. The majority of the anion-π interacting residues are located in regions with helical secondary structure. Analysis of stabilization centers for these complexes showed that all of the six residues capable of anion-π interactions are important in locating one or more of such centers. We found that anion-π interacting residues are sometimes involved in simultaneous interactions with halogens as well. With all that in mind, we can conclude that the anion-π interactions can show significant influence on molecular organization and on the structural stability of the complexes of proteins and halogen-containing non-natural amino acids. Their influence should not be neglected in supramolecular chemistry and crystal engineering fields as well.

Glycomic analyses over the years have revealed that non-vertebrate eukaryotes express oligosaccharides with inorganic and zwitterionic modifications which are either occurring in different contexts as compared to, or are absent from, mammals. Examples of anionic N-glycans (carrying sulphate or phosphate) are known from amoebae, fungi, molluscs and insects, while zwitterionic modifications by phosphorylcholine, phosphoethanolamine and aminoethylphosphonate occur on N-, O- and lipid-linked glycans from trichomonads, annelids, fungi, molluscs, insects, cestodes and nematodes. For detection of zwitterionic and anionic glycans, mass spectrometry has been a key method, but their ionic character affects the preparation and purification; therefore, as part of a glycomic strategy, the possibility of their presence must be considered in advance. On the other hand, their ionisation and fragmentation in positive and negative ion mode mass spectrometry as well as specific chemical or enzymatic treatments can prove diagnostic to their analysis. In our laboratory, we combine solid-phase extraction, reversed and normal phase HPLC, MALDI-TOF MS, exoglycosidase digests and hydrofluoric acid treatment to reveal N-glycans modified with anionic and zwitterionic moieties in a wide range of organisms. It is to be anticipated that, as more species are glycomically analysed, zwitterionic and anionic modifications of N-glycans will prove rather widespread. This knowledge is - in the longer term - then the basis for understanding the function of this cornucopia of glycan modifications.

Lanthanum-modified bentonite has potential for wide application in eutrophication control. We investigated P adsorption on a lanthanum-modified bentonite by analysis of adsorption kinetics, equilibrium, and the effect of environmental factors. P adsorption closely followed the pseudo-second-order kinetic model, and the isotherm was well described by the Langmuir model. This adsorbent could effectively immobilize P into the sediment, but the adsorption process was strongly dependent on pH, anions, and low molecular weight organic acids (LMWOAs). P adsorption increased with increasing pH from 0.52 mg P/g at pH 3.0 to 0.93 mg P/g at pH 7.0 with no adsorption at pH 11. P adsorption was strongly inhibited in the presence of anions and three LMWOAs, with P even re-released at high concentrations. These environmental factors should be given significant attention when considering the application of lanthanum-modified bentonite in eutrophication control.

Free milk-type oligosaccharides are produced during pregnancy and lactation and may have an impact on several cells in the immune system. Our aim was to investigate if patients with isolated hyperprolactinaemia, not related to pregnancy, also have increased synthesis and urinary excretion of milk-type oligosaccharides and to compare the excretion pattern with that found during pregnancy. Urine samples were collected as morning sample from 18 patients with hyperprolactinaemia, 13 healthy controls with normal prolactin levels and four pregnant women. After purification, lactose and free oligosaccharides were analysed and quantified by high-performance anion-exchange chromatography with pulsed amperometric detection. The identity of peaks was confirmed by exoglycosidase treatment and comparison with oligosaccharide standards. Prolactin was measured in serum collected between 09 and 11 a.m. by a standardized immunochemical method. Patients with hyperprolactinaemia had higher urinary excretion of lactose than normoprolactinemic controls and urinary lactose correlated positively to prolactin levels (r = 0.51, p < 0.05). Increased levels of the fucosylated oligosaccharides 2-fucosyl lactose and lacto-di-fucotetraose were found in urine from three and two patients, respectively. The acidic oligosaccharide 3-sialyl lactose was found in high amount in urine from two patients with prolactin of >10,000 mU/l. However, pregnant women in their third trimester had the highest concentration of all these oligosaccharides and excretion increased during pregnancy. This study is first to show that both lactose and certain fucosylated and sialylated milk-type oligosaccharides are increased in some patients with hyperprolactinaemia. It remains to elucidate the functional importance of these findings.

The photochemical properties of two basic easily synthesized isatin N(2)-phenylhydrazones were investigated. Contrary to the corresponding isatin N(2)-diphenylhydrazones, only Z-isomers were isolated from the reaction mixtures during the synthesis due to their stabilization by intramolecular hydrogen bonding. Although the presence of the C=N double bond creates conditions for the formation of a simple on-off photoswitch, the low photochemical quantum yield and particularly the low switching amplitude in absorbance hamper their photochromic applications. However, the addition of strongly basic anions to phenylhydrazone solutions leads to isatin NH group deprotonation and creates a new diazene T-type Vis-Vis photochromic system with sufficiently separated absorption maxima. Interestingly, although the thermally stable A-form is also photostable in ambient light, its irradiation with a stronger LED source leads to thermally unstable B-form formation which rapidly isomerizes back to the corresponding A-form. The process is reversible and switching cycles can be repeated in both directions. The important advantages of this two-component organic chromophore-inorganic anion photochromic system are its easy synthesis, easy handling due to its insensitivity to room light, easy further structural modification and reversibility. The corresponding photochemical quantum yield, however, remains relatively low (Φ ∼ 0.001). The theoretically calculated properties are in agreement with the obtained experimental results and support the proposed reaction mechanism.

Cellular ribozymes exhibit catalytic activity in media containing large numbers of anionic compounds and macromolecules. In this study, the RNA cleavage activity of the hammerhead ribozyme induced by Mg(2+) was investigated using the solutions containing background nucleic acids, small phosphate and carboxylic acid compounds, and neutral polymers. Analysis of the substrate cleavage kinetics showed that the anionic compounds do not affect the ribozyme activity in Mg(2+)-saturated solutions and there is almost no effect of the anion-Mg(2+) complexes formed. On the other hand, the rate of substrate cleavage in Mg(2+)-unsaturated solutions was reduced under conditions of a high background of anionic compounds found in cells. The extent of the reduction was more with a greater net negative charge, caused by decreased amounts of Mg(2+) that could be used for the ribozyme reaction. It was remarkable that background DNA and RNA molecules having phosphodiester bonds reduced the cleavage rate as much as adenosine monophosphates having a charge of -2 when the effects of the same amount of phosphate groups were compared. Greater reductions in rates than those expected from the molecular charge were also observed in the background of fatty acids that form micelles. An addition of poly(ethylene glycol) to the solutions partially restored the ribozyme activity, suggesting a possible role of macromolecular crowding in counteracting the inhibitory effects of background anions on the ribozyme reaction. The results have biological and practical implications with respect to the effects of molecular environment on the efficiency of ion binding to RNA.

We have explored an effect of Hofmeister anions, Na2SO4, NaCl, NaBr, NaNO3, NaSCN and NaClO4, on stability and amyloid fibrillization of hen egg white lysozyme at pH 2.7. The stability of the protein was analyzed by differential scanning calorimetry. The Hofmeister effect of the anions was assessed by the parameter dT trs/d[anion] (T trs, transition temperature). We show that dT trs/d[anion] correlates with anion surface tension effects and anion partition coefficients indicating direct interactions between anions and lysozyme. The kinetic of amyloid fibrillization of lysozyme was followed by Thioflavin T (ThT) fluorescence. Negative correlation between dT trs/d[anion] and the nucleation rate of fibrillization in the presence of monovalent anions indicates specific effect of anions on fibrillization rate of lysozyme. The efficiency of monovalent anions to accelerate fibrillization correlates with inverse Hofmeister series. The far-UV circular dichroism spectroscopy and atomic force microscopy findings show that conformational properties of fibrils depend on fibrillization rate. In the presence of sodium chloride, lysozyme forms typical fibrils with elongated structure and with the secondary structure of the β-sheet. On the other hand, in the presence of both chaotropic perchlorate and kosmotropic sulfate anions, the fibrils form clusters with secondary structure of β-turn. Moreover, the acceleration of fibril formation is accompanied by decreased amount of the formed fibrils as indicated by ThT fluorescence. Taken together, our study shows Hofmeister effect of monovalent anions on: (1) lysozyme stability; (2) ability to accelerate nucleation phase of lysozyme fibrillization; (3) amount, and (4) conformational properties of the formed fibrils.

In the present study, we use theory and modeling to investigate K(+) carrier valinomycin (Vln) as a classical anionophore. We discuss formation of the ion pair VlnK(+), Cl(-) versus encapsulation of the anion into VlnCl(-) complex as two alternative mechanisms that could account for surprisingly high anionophoretic activity of the cyclic peptide (Riddell and Zhou in J Inorg Biochem 55:55-279, 1994), meanwhile constructing kinetic models to help distinguish between the two. The study is guided by the idea to create "valinomycin for anions" and in this respect the selectivity problem is at the heart, as synthetic anionophores are expected to have the same issues with the counterion translocation as Vln has. The study helps to understand what Vln really is and so what "valinomycin for anions" has to be. Furthermore, using recent examples, we explore how Vln has been utilized as a tool for research in the two different fields, with an aim to illustrate advantages and potential of basic scientific methods over supramolecular way, celebrating victory of science over commonsense.

The anion recognitions of tetra-(2-formamido) phenyl porphyrin (APP), tetra-(2-ureido) phenyl porphyrin (UPP), and their zinc derivatives (ZnAPP and ZnUPP) to three anions (Cl(-), H2PO4 (-), CH3COO(-)) were studied using quantum mechanical calculations (QM) and molecular dynamics (MD) simulations. The density functional theory (DFT) calculations at M06-2X/6-31G (d, p) level indicated that the anion recognition ability of ZnAPP was better than that of APP, and the anion selectivity was in the order Cl(-) < H2PO4 (-) < CH3COO(-). The selectivity trends for ZnUPP and UPP were found to be H2PO4 (-) < Cl(-) < CH3COO(-). The structures, thermodynamic properties, and recognition mechanisms were discussed in detail. The 2 ns MD simulations were then carried out for anion@ZnAPP and anion@ZnUPP complexes in mixed solvent DMSO/water. The MD simulation results showed that anion@ZnUPP complexes exhibited higher stability than anion@ZnAPP, which was in good agreement with QM results. H-bonds formed between the anions and the side-chains of receptors, and zinc coordination bonds with anions contributed significantly to the stability of complexes. The anion selectivity of ZnAPP and ZnUPP in the solvent phase were also discussed and compared with those in the gas phase.

The photolysis of the antimicrobial triclocarban (TCC) in aqueous systems under simulated sunlight irradiation was studied. The effects of several abiotic parameters, including solution pH, initial TCC concentration, presence of natural organic matter, and most common inorganic anions in surface waters, were investigated. The results show that the photolysis of TCC followed pseudo-first-order kinetics. The TCC photolysis rate constant increased with increasing solution pH and decreasing the initial TCC concentration. Compared with the TCC photolysis in pure water, the presence of aqueous bicarbonate, nitrate, humic acids, and its sodium salt decreased the TCC photolysis rate, but fulvic acid increased the TCC photolysis rate. The electron spin resonance and reactive oxygen species scavenging experiments indicated that TCC may undergo two different types of phototransformation reactions: direct photolysis and energy transfer to generate (1)O2. The main degradation products were tentatively identified by gas chromatography interfaced with mass spectrometry (GC-MS), and a possible degradation pathway was also proposed.

LOV domains are the light sensitive parts of phototropins and many other light-activated enzymes that regulate the response to blue light in plants and algae as well as some fungi and bacteria. Unlike all other biological photoreceptors known so far, the photocycle of LOV domains involves the excited triplet state of the chromophore. This chromophore is flavin mononucleotide (FMN) which forms a covalent adduct with a cysteine residue in the signaling state. Since the formation of this adduct from the triplet state involves breaking and forming of two bonds as well as a change from the triplet to the singlet spin state, various intermediates have been proposed, e.g. a protonated triplet state (3)FMNH(+), the radical anion (2)FMN˙(-), or the neutral semiquinone radical (2)FMNH˙. We performed an extensive search for these intermediates by two-dimensional transient absorption (2D-TA) with a streak camera. However, no transient with a rate constant between the decay of fluorescence and the decay of the triplet state could be detected. Analysis of the decay associated difference spectra results in quantum yields for the formation of the adduct from the triplet of ΦA(LOV1) ≈ 0.75 and ΦA(LOV2) ≈ 0.80. This is lower than the values ΦA(LOV1) ≈ 0.95 and ΦA(LOV2) ≈ 0.99 calculated from the rate constants, giving indirect evidence of an intermediate that reacts either to form the adduct or to decay back to the ground state. Since there is no measurable delay between the decay of the triplet and the formation of the adduct, we conclude that this intermediate reacts much faster than it is formed. The LOV1-C57S mutant shows a weak and slowly decaying (τ > 100 μs) transient whose decay associated spectrum has bands at 375 and 500 nm, with a shoulder at 400 nm. This transient is insensitive to the pH change in the range 6.5-10.0 but increases on addition of β-mercaptoethanol as the reducing agent. We assign this intermediate to the radical anion which is protected from protonation by the protein. We propose that the adduct is formed via the same intermediate by combination of the radical ion pair.

Anion exchange polystyrene nanofiber materials (AE) were prepared by electrospinning followed by two-step functionalization of the nanofiber surface by chlorosulfonic acid and ethylendiamine. The photoactive character of these materials was introduced through adsorption of the tetra-anionic 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin photosensitizer (TPPS-AE) on the nanofiber surface or by encapsulation of the nonpolar 5,10,15,20-tetraphenylporphyrin photosensitizer (AE(TPP)) into the nanofibers. Anion exchange nanofiber materials with porphyrins are characterized by a high ion-exchange capacity, photogeneration of singlet oxygen O2((1)Δg), and singlet oxygen-sensitized delayed fluorescence. Due to the photogeneration of cytotoxic O2((1)Δg), the nanofibers exhibited oxidation of the external substrates in aqueous solution and an efficient antibacterial effect when activated by simulated daylight. Adsorption of both TPPS and I(-) on the surface of AE led to the formation of more efficient I-TPPS-AE materials. Rapid photooxidation of I(-) by O2((1)Δg), and the formation of another cytotoxic species, I3(-), on the surface of the nanofibers were responsible for the increased antibacterial properties of I-TPPS-AE and the prolonged antibacterial effect in the dark.

Amphiphilic ruthenium(II) complexes II–IV were synthesized and their photophysical properties were investigated in the presence of anionic (SDS), cationic (CTAB) and neutral (Triton X-100) micelles. The absorption and emission spectral data in the presence of micelles show that these Ru(II) complexes are incorporated in the micelles. There are two types of interaction between complexes I–IV and the micelles: hydrophobic and electrostatic. In the case of cationic micelles (CTAB), the hydrophobic interactions are predominant over electrostatic repulsion for the binding of cationic complexes II–IV with CTAB. In the case of anionic micelles (SDS), electrostatic interactions seem to be important in the binding of II–IV to SDS. Hydrophobic interactions play a dominant role in the binding of II–IV to the neutral micelles, Triton X-100. Based on the steady state and luminescence experiments, the enhancement of luminescence intensity and lifetime in the presence of micelles is due to the protection of the complexes from exposure to water in this environment.

The interactions between chemosensors, donor-π-acceptor (D-π-A) dipolar organoboron derivatives, and different (CN⁻, F⁻, Cl⁻, and Br⁻) anions have been theoretically investigated using DFT approaches. Theoretical investigations have been performed to explore the optical, electronic, charge transport, and stability properties of organoboron derivatives as charge transport and luminescent materials for organic light emitting devices (OLEDs). It turned out that the unique selectivity of organoboron derivatives for F⁻/CN⁻ is ascribed to the formation of chemosensors complexes. The frontier molecular orbitals (FMOs) and local density of states analysis have turned out that the vertical electronic transitions of absorption and emission for chemosensors and their F⁻/CN⁻ complexes are characterized as intramolecular charge transfer (ICT). The formation of complexes has effect on the distribution of FMOs and the flowing direction of electronic density for vertical transition. The study of substituent effects suggests that the derivatives with thiophene (2), furan (3), and 1H-pyrrole (4) fragments, are expected to be promising candidates for ratiometric fluorescent fluoride and cyanide chemosensors as well as chromogenic chemosensors, whereas derivatives with pyridine (5) and pyrimidine (6) fragments can serve as chromogenic chemosensors only. Furthermore, all the derivatives are promising luminescent and hole transport materials and 2, 3, 5, and 6 can serve as electron transport materials for OLEDs.

Quantum molecular simulations of chemical systems can provide detailed information that is often inaccessible to direct experimental measurement. Pyrimidine is an interesting π-electron heterocyclic aromatic system which acts as the building block of many nucleic acid bases. The hydrogen bonds associated with the 2, 4, and 6-substituted pyrimidine and its hydrogen sulfate anion are considered for this current work. The experimental and computational evidence for the strength of these intra and intermolecular hydrogen are determined using vibrational spectra and quantum chemical calculations. Thus the effect of hydrogen bonding on the title compound is studied using its geometrical parameters, interaction energies, and vibrational spectra. Aromaticity and charge transfer studies have been performed to ascertain the aromatic behavior of the molecule. The PES scan studies have been done by varying the bond length to ascertain the protonation process of the compound. The IR spectral red shift (∼100 cm⁻¹), blue shift (∼97 cm⁻¹) and broadening of the polar stretching peaks shows the inter and intramolecular hydrogen bonding strength. Bond length alternation of proton donors along with the enormous interaction energies (∼0.5-150 kJ mol⁻¹) between the lone pair and proton donors provides clear evidence for this hydrogen bonding. The charge transfer due to the methyl substitutions which enhances the possibility of hydrogen bonding has been discussed. The main scope of this work is to study the protonation and hydrogen bonding associated with charge transfer which has great effect on the 2-amino-4, 6-dimethyl pyrimidinium hydrogen sulfate (ADHS) molecule.

The short-range properties of alkylpiperazine ionic liquids paired with propionate and lactate anions were analyzed and their affinity for CO₂ molecules studied using density functional theory. Anion-cation interactions led to the development of strong intermolecular hydrogen bonding through the cation amine position, as confirmed through variations in structural and vibrational properties upon pair formation. Topological analysis via the atoms-in-molecules approach revealed the development of intense bond and ring critical points in the intermolecular regions, which is in agreement with charge transfer from lone pairs in anion oxygen atoms of carboxylate groups through antibonding orbitals in cation amine groups. Such anion-cation interactions are weakly dependent on cation alkyl chain length but are remarkably affected by the presence of an anion hydroxyl group. Interactions with CO₂ molecules are stronger for anions than for cations, especially for propionate anions, and are also affected strongly by the anion hydroxyl group.

Water exchange reactions of the complexes Al(H₂O)₅(L)]²⁺·H₂O for L = →OCN⁻, F⁻, CF₃⁻, →NC⁻, →CN⁻, Cl⁻, Br⁻, H⁻, SH⁻, OH⁻, →NCO⁻, →NCS⁻, →SCN⁻, CF₃CH₂⁻, CH₃⁻, Et⁻, i-Pr⁻ and t-but⁻, were studied by DFT calculations (B3LYP/6-311+G**). The reactions follow a dissociative (D) pathway for Al(H₂O)₅(L)]²⁺·H₂O to form the five-coordinate intermediate [Al(H₂O)₄L]²⁺·2H₂O for the weaker donor ligands of the series. On increasing the donor strength of L, the five-coordinate intermediate becomes significantly more stable than the reactant state. At this point there is a mechanistic changeover to an associative (A) pathway for [Al(H₂O)₄L]²⁺·2H₂O as reactant to form a six-coordinate intermediate Al(H₂O)₅(L)]²⁺·H₂O. For some of the anionic ligands L = → NC⁻, →CN⁻, Cl⁻, OH⁻ and →SCN⁻) the energy gap between the reactant and intermediate states is small, such that the water exchange mechanism lies in the boarder of dissociative and associative pathways. The water exchange process involves cis- and trans-orientated transition states to form the product state that is similar to the reactant state.

Inclusion of 6-methoxy-1-methylquinolinium (C1MQ) in the cavity of cucurbit[7]uril (CB7) was studied by absorption, fluorescence, NMR and isothermal calorimetric methods in aqueous solution at 298 K. The free C1MQ exhibited dual-exponential fluorescence decay kinetics due to the two torsional isomers differing in the orientation of the methoxy moiety relative to the heterocyclic ring. The enthalpy-driven encapsulation of the heterocycle in CB7 led to a very stable 1 : 1 complex with a binding constant of (2.0 ± 0.4) × 10(6) M(-1). The rate of C1MQ-CB7 complex dissociation was found to be comparable to the NMR timescale. Because the methoxy moiety is oriented outward from the host, its s-cis-s-trans isomerization is slightly affected by the confinement. Inclusion complex formation significantly slowed down the photoinduced electron transfer from I(-) and N3(-) to the singlet-excited C1MQ, but did not preclude the reaction because long distance electron transfer occurred through the wall of the CB7 macrocycle. Due to the large difference in the quenching rate constant for free and encapsulated forms, C1MQ is an excellent probe for the study of the inclusion of nonfluorescent compounds in CB7 in the presence of Cl(-) or Br(-).

In this work, we investigated in detail the structural characteristics of mixtures of choline chloride and urea with different urea contents by performing molecular dynamic (MD) simulations, and offer possible explanations for the low melting point of the eutectic mixture of choline chloride and urea with a ratio of 1:2. The insertion of urea molecules was found to change the density distribution of cations and anions around the given cations significantly, disrupting the long-range ordered structure of choline chloride. Moreover, with increasing urea concentration, the hydrogen bond interactions between choline cations and Cl(-) anions decreased, while those among urea molecules obviously increased. From the hydrogen bond lifetimes, it was found that a ratio of 1:2 between choline chloride and urea is necessary for a reasonable strength of hydrogen bond interaction to maintain the low melting point of the mixture of choline chloride with urea. In addition, it was also deduced from the interaction energies that a urea content of 67.7 % may make the interactions of cation-anion, cation-urea and anion-urea modest, and thus results in the lower melting point of the eutectic mixture of choline chloride and urea. The present results may offer assistance to some extent for understanding the physicochemical properties of the eutectic mixture of choline chloride and urea, and give valuable information for the further development and application of deep eutectic solvents.

Among the medical applications of nanoparticles, their usage as photosensitizer (PS) carriers for photodynamic therapy (PDT) has attracted increasing attention. In the present study we explored the morphological and photophysical properties of core-shell PMMA nanoparticles (PMMA-NPs) electrostatically post-loaded with the synthetic, water soluble 5,10,15,20-tetrakis(4-sulphonatophenyl)-porphyrin (TPPS4). pH response and singlet oxygen analyses of differently loaded samples proved the high capability of the PMMA-NPs to shield the PS from the environment, while retaining the PS singlet oxygen production capability. Preliminary in vitro imaging and phototoxicity experiments on HepG2 cells demonstrated the efficacy of the system to trigger photoinduced cell death in the culture.

Photochemical degradation of fluoroquinolone ciprofloxacin (CIP) in water by UV and UV/H₂O₂ were investigated. The degradation rate of CIP was affected by pH, H₂O₂ dosage, as well as the presence of other inorganic components. The optimized pH value and H₂O₂ concentration were 7.0 and 5 mM. Carbonate and nitrate both impeded CIP degradation. According to liquid chromatography-tandem mass spectrometry analysis, four and 16 products were identified in UV and UV/H₂O₂ system, respectively. Proposed degradation pathways suggest that reactions including the piperazinyl substituent, quinolone moiety, and cyclopropyl group lead to the photochemical degradation of CIP. Toxicity of products assessed by Vibrio qinghaiensis demonstrated that UV/H₂O₂ process was more capable on controlling the toxicity of intermediates in CIP degradation than UV process.

This work aimed to investigate the effectiveness of ultraviolet (UV) radiation on the degradation of the antimicrobial triclocarban (TCC). We investigated the effects of several operational parameters, including solution pH, initial TCC concentration, photocatalyst TiO₂ loading, presence of natural organic matter, and most common anions in surface waters (e.g., bicarbonate, nitrate, and sulfate). The results showed that UV radiation was very effective for TCC photodegradation and that the photolysis followed pseudo-first-order kinetics. The TCC photolysis rate was pH dependent and favored at high pH. A higher TCC photolysis rate was observed by direct photolysis than TiO₂ photocatalysis. The presence of the inorganic ions bicarbonate, nitrate, and sulfate hindered TCC photolysis. Negative effects on TCC photolysis were also observed by the addition of humic acid due to competitive UV absorbance. The main degradation products of TCC were tentatively identified by gas chromatograph with mass spectrometer, and a possible degradation pathway of TCC was also proposed.

A simple and convenient method of reducing monosaccharide assay is proposed. A Si(IV)-Mo(VI) solution (pH 4.9) was yellow due to the formation of the 11- and/or 12-molybdosilicate(VI) anions. By the addition of a reducing saccharide, glucosamine, the mixture turned to blue gradually, indicating that the Mo(VI) species was reduced by the saccharide to form a blue molybdosilicate anion. The molybdenum blue formation occurred more quickly when a water-miscible organic solvent, dimethyl sulfoxide, was added to the Si(IV)-Mo(VI) solution. Thus, 0.01% level glucosamine can be determined colorimetrically with microtiter plate. Oligochitosan would not interfere with the determination of the glucosamine at the same concentration. Also, a remarkable blue color development of the Si(VI)-Mo(VI) solution was observed by the addition of glucose. On the other hand, maltose, cellobiose, and water-soluble starch at the same concentration level gave no significant coloration of the reaction mixture. Thus, the present monosaccharide assay can be applied advantageously to evaluate the saccharification to produce glucosamine and glucose.

6-Mercaptopurine (6-MP) is one of a large series of purine analogues which has been found active against human leukemias. The equilibrium dialysis, circular dichroism (CD) and molecular docking were employed to study the binding of 6-MP to human serum albumin (HSA). The binding of 6-MP to HSA in the equilibrium dialysis experiment was detected by measuring the displacement of 6-MP by specific markers for site I on HSA, warfarin (RWF), phenylbutazone (PhB) and n-butyl p-aminobenzoate (ABE). It was shown, according to CD data, that binding of 6-MP to HSA leads to alteration of HSA secondary structure. Based on the findings from displacement experiment and molecular docking simulation it was found that 6-MP was located within binding cavity of subdomain IIA and the space occupied by site markers overlapped with that of 6-MP. Displacement of 6-MP by the RWF or PhB was not up the level expected for a competitive mechanism, therefore displacement of 6-MP was rather by non-cooperative than that the direct competition. Instead, in case of the interaction between ABE and 6-MP, when the little enhancement of the binding of ABE by 6-MP was found, the interaction could be via a positively cooperative mechanism.