Aromatic Carboxylate Research Articles

Judd-Ofelt analysis of dimeric europium carboxylates with gradually changing distortions of the crystal field around Eu3+ ion

Experimental and theoretical Judd-Ofelt intensity parameters Ωλ, rates of radiative Arad and nonradiative Anrad processes, and quantum efficiency of luminescence were calculated for a series of related aromatic and aliphatic carboxylates [Eu2(RCOO)6L2] (L - 1,10-phenanthroline or 2,2′-bipyridine) using the LUMPAC software. The behavior of these characteristics in the sequence of europium carboxylates with the gradually changing distortions of the crystal field, which is mainly caused by variation in the bond lengths of the bridging-cyclic COO− groups with Eu3+ ion, was analyzed. A correlation between the changes in the value of the Ω2 intensity parameter, the radiative rate Arad, and the ratio of metal-ligand bond lengths in the Eu coordination polyhedron was demonstrated. The dependence of the parameter Ω2 on the distribution of metal-ligand orbital overlap among Eu-ligand bonds of the compound was revealed. The higher Ω2 values in the set of aromatic carboxylates are associated with a more distorted nearest environment of the Eu3+ ion which is caused by the influence of the bulky R fragments. It is shown that the intensity of f-f transitions of the Eu3+ ion in the compounds under investigation is determined foremost by the dynamic coupling (DC) mechanism. The contribution of this mechanism to the parameters Ω2 and Ω4 is close to 100 %, its contribution to the Ω6 parameter is 85–92 %. The luminescence quantum efficiency for the studied europium carboxylates varies in the range of 52–74 %.

Carboxylate-Based Metal-Organic Framework and Coordination Polymer Glasses: Progress and Perspectives.

ConspectusCoordination polymers (CPs) and metal-organic frameworks (MOFs) represent versatile materials with diverse structural and functional properties, making them appealing for various applications. However, their conventional forms, which are typically synthesized as powders or crystals, pose challenges due to limited processability and mechanical fragility. Recently, CP/MOF glasses have emerged as promising alternatives, offering enhanced processability while retaining some of the unique characteristics shown in the mother crystalline materials. Despite the prevalence of carboxylate ligands in CP/MOF synthesis, the development of carboxylate-based CP/MOF glasses has been limited compared to that of zeolitic-imidazole framework (ZIF)-based glasses. This is attributed to the strong metal-ligand bonds and low thermal stability of carboxylic acids, which hinder their melting in CP/MOF structures. Nonetheless, recent advancements have led to a surge in methods for synthesizing carboxylate-based CP/MOF glasses. So far, desolvation and melt-quenching have been introduced for achieving glass structures from CP/MOF precursors.The first melt-quenched MOF glass was reported in 2015 with ZIFs. However, we informally observed the melting of the MOF during thermal decomposition research of aliphatic carboxylate-based MOFs as a sacrificial template dating back to 2013. In that study, aliphatic ligands, instead of aromatic carboxylate, were employed due to their high lability, lower thermal stability, and high degree of freedom, which facilitated pyrolysis. The results were published with a focus on synthesizing hierarchically porous MgO via the pyrolysis of an aliphatic ligand-based Mg-MOF in an inert environment. A decade later, it was revisited and studied as the first melt-quenched carboxylate-based MOF glass, converted from a crystalline MOF through the liquid phase before decomposition during the heating process.This Account aims to introduce six studies, including the aforementioned example, on the synthesis of CP/MOF glasses from carboxylate-based CPs/MOFs that have been published so far. To overcome the challenges with aromatic carboxylates in CP/MOF glass formation, the metal coordination sphere should be altered and the degree of freedom in the ligands should be increased. Based on these approaches, the strategies for vitrification of carboxylate-based CPs/MOFs can be divided into two categories: desolvation and melt-quenching. Desolvation can be preceded by vapor perturbation such as hydration. Carboxylate-based CP/MOF glasses possess the potential to expand into a broader range of applications beyond those of existing CP/MOF glasses. Alongside the diversity offered by carboxylic acid ligands, these materials mirror the extensive range of applications previously explored in the existing carboxylate-based CP/MOF crystals. Moreover, their high processability, inherent to glass materials, enables their applications in various industrial fields. This versatility may extend to previously unexplored areas of utilization such as a novel class of bioactive glass.

Direct Ethylene Purification from a Four-Component Gas Mixture by a Microporous MOF with Aromatic Pore Surface and Carboxylates.

The single-step purification of ethylene (C2H4) from a mixture of carbon dioxide (CO2), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) was achieved through MOF Compound-1, where the aromatic pore surface and carboxylates selectively recognized C2H6 and CO2, respectively, resulting in a reversal of the adsorption orders for both gases (C2H6 > C2H4 and CO2 > C2H4). Breakthrough testing verified that the C2H4 purification ability could be enhanced 2.6 times after adding impure CO2. Grand Canonical Monte Carlo (GCMC) simulations demonstrate that there are interactions between CO2 and C2H6 molecules as well as between CO2 molecules themselves. These interactions contribute to the enhancement of the C2H4 purification ability upon the addition of CO2 and the increased adsorption of CO2.

Ameliorating tannery sludge dewaterability by disintegration of extracellular biopolymers with FeCl3-MnSO4/oxalic acid/sodium percarbonate: Spectroscopic profiling of dissolved organic matter in sludge filtrate

Effectual sludge dewatering techniques are strongly desired by industrial wastewater treatment plants. In this work, we scrutinised the efficacy of various Fenton based complex mediated processes like ferric chloride (FeCl3)/oxalic acid (OA)/sodium percarbonate (SPC) (FOS), FS (without OA), manganese sulphate (MnSO4)/oxalic acid (OA)/sodium percarbonate (SPC) (MOS) and MS (without OA) for which capillary suction time (CST) was attained as follows: MS (204 s) < MOS (180 s) & FS (180 s) < FOS (174 s) at pH 3. This implied the role of chelating agent (OA) in improving sludge dewaterability by disintegrating Extracellular Polymeric Substances (EPS) and releasing converted free water from the sludge flocs. FTIR results of sludge samples revealed the higher release of aromaticity after treatment process. Presence of aromatic carboxylate compounds were confirmed by GC–MS analysis. A detailed inquisition on the dissolved organic matter (DOM) of filtrate samples using 3DEEM fluorescence methods like second derivative Accumulative Fluorescence Emission (AFE), Fluorescence Regional Integration (FRI) and UV–Visible spectroscopic method like multipeak Gaussian fitting were performed that signified Microbial Soluble Products.

Термическое разложение бензоатов и аминобензоатов Mn (II), Co (II), Ni (II), Cu (II)

The article discusses the main methods for obtaining carbon composite nanomaterials and highlights the thermolysis method as one of them. To understand the essence of thermal decomposition processes as a synthesis method for carbon nanomaterials, thermolysis of aromatic carboxylates of such elements as manganese(II), cobalt(II), nickel(II), and copper(II) was considered. The article thoroughly discusses the synthesis procedure for these metal carboxylates under simple conditions. The thermal decomposition process was carried out in two environments (air as oxidizing one and argon as neutral one) to compare the products obtained. For a detailed study of the decomposition processes of manganese(II), cobalt(II), nickel(II), and copper(II) carboxylates, thermal analysis methods (TG and DSC) were used on a Netzsch 449 Jupiter synchronous thermal analyzer. To study the morphology and composition of the products, the methods of X-ray phase analysis, optical and scanning electron microscopy, and X-ray fluorescence microanalysis were used. The devices used were a Rigaku Ultima IV X-ray diffractometer and a scanning electron microscope with a Jeol JSM-7001F. The mechanisms of thermal decomposition of manganese(II), cobalt(II), nickel(II), and copper(II) carboxylates were suggested. For a more accurate determination of the composition of the synthesis products of manganese(II), cobalt(II), nickel(II), and copper(II) carboxylates and for a more accurate description of the processes of thermal decomposition of these salts, the corresponding aromatic carboxylic acids were also thermally decomposed. The appendix to the article presents thermograms of manganese(II), cobalt(II), nickel(II), and copper(II) aromatic carboxylates.

Получение порошковых углеродных композитных наноматериалов термическим разложением ароматических карбоксилатов Fe (III)

The article discusses the principal methods for obtaining carbon composite nanomaterials and highlights the thermolysis method as one of them. In order to understand the essence of thermal decomposition processes as a method for synthesis of carbon nanomaterials, aromatic iron(III) carboxylates have been considered. These are iron(III) 8-hydroxyquinolinate, benzoate, salicylate, phthalate, and p-aminobenzoate. The article discusses the procedure for the synthesis of these iron(III) carboxylates under standard conditions in detail. The thermal decomposition process was carried out in two media (air as oxidizing one and argon as neutral one) to compare the obtained products. For a detailed study of the processes of decomposition of iron(III) carboxylates, the thermal analysis methods (TG and DSC) were used on a Netzsch 449 Jupiter synchronous thermal analyzer. In order to study the morphology and composition of the products, X-ray phase analysis, optical and scanning electron microscopy, as well as X-ray fluorescence microanalysis were used. We used a Rigaku Ultima IV X-ray diffractometer and a scanning electron microscope with a Jeol JSM-7001F elemental microanalysis attachment. Based on the obtained results, the expected formulas of the initial iron(III) carboxylates were calculated. The mechanisms of the processes occurring during the thermal decomposition of iron(III) aromatic carboxylates were also proposed. For a more accurate determination of the composition of the synthesized iron(III) carboxylates and a more appropriate description of the processes of thermal decomposition of these salts, the corresponding aromatic carboxylic acids were also subjected to thermal decomposition. The appendix to the article contains the data for a more accurate interpretation of the results and a more detailed description of the thermal decomposition processes.

Octacalcium phosphate with incorporated terephthalate ion derivatives: novel guest molecules and unique fluorescence properties.

Octacalcium phosphate (OCP), an inorganic compound with a layered structure that can incorporate various carboxylic acids, exhibits fluorescence when aromatic carboxylate ions are present in the interlayers. However, the incorporation of carboxylate ions into OCP involves molecular selectivity, and the synthesis of novel OCP materials with incorporated terephthalate ion derivatives is particularly challenging. In this study, we incorporated 4-(carboxymethyl)benzoate and 1,4-phenylenediacetate ions into OCP for the first time and investigated the resulting fluorescence properties. The relationship between the (100) interplanar spacing and size of the incorporated dicarboxylate ions revealed that 4-(carboxymethyl)benzoate ions have a relaxed structure in the OCP interlayers, whereas the structure of the 1,4-phenylenediacetate ions is elongated by approximately 10% relative to that of the stable conformation. OCP with incorporated 1,4-phenylenediacetate ions showed blue fluorescence at 286 nm under 254 nm excitation. In contrast, distinct from previously reported fluorescent OCPs, OCP with incorporated 4-(carboxymethyl)benzoate ions exhibited two-colour fluorescence, with pink emission under 254 nm excitation and blue emission under 312 and 365 nm excitation. This OCP material exhibiting fluorescence at two wavelengths in the visible-light range offers new possibilities for practical applications. In particular, these unique fluorescence characteristics combined with the excellent biological properties of OCP can be exploited to develop novel biofriendly fluorescent probes. These findings contribute to an improved understanding of fundamental calcium phosphate chemistry and should encourage further research on functional OCP materials.

Diverse sedimentary organic matter within the river-aquifer interface drives arsenic mobility along the Meghna River Corridor in Bangladesh

In alluvial aquifers with near-neutral pH and high dissolved arsenic (As) concentrations, the presence and character of sedimentary organic matter (SOM) regulates As mobility by serving as an energetically variable source of electrons for redox reactions or forming As–Fe-OM complexes. Near tidally and seasonally fluctuating rivers, the hyporheic zone (HZ), which embodies the mixing zone between oxic river water and anoxic shallow groundwater, may precipitate (or dissolve) iron (Fe)-oxides which sequester (or mobilize) As. To understand what is driving the mobilization of As within a shallow aquifer and riverbank sands adjacent to the tidally fluctuating Meghna River, we characterized the chemical reactivity of SOM from the sands, and a silt and clay layer, underlying the HZ and aquifer, respectively. Dissolved As (50–500 μg/L) and Fe (1–40 mg/L) concentrations increase with depth within the shallow aquifer. Similar vertical As and Fe concentration gradients were observed within the riverbank sands where concentrations of the products of reductive dissolution of Fe-oxides increase with proximity to the silt layer. Compared to all other sediments, the SOM in the clay aquitard contains older, more recalcitrant, terrestrially-derived material with high proportions of aromatic carboxylate functional groups. The shallow silt layer contains fresher SOM with higher proportions of amides and more labile polysaccharide moieties. The SOM in both the riverbank and aquifer is terrestrially-derived and humic-like. The labile SOM from the silt layer drives the microbially mediated reductive dissolution of As-bearing Fe-oxides in the HZ. In contrast, the carboxylate-rich SOM from the clay aquitard maintains dissolved As concentrations at the base of the aquifer by complexing with soluble As and Fe. This highlights that SOM-rich fine (silt or clay) layers in the Bengal basin drive As and Fe mobility, however, the specific processes mobilizing As and Fe depend on the lability of the SOM.

Green Synthesis of CoZn-Based Metal-Organic Framework (CoZn-MOF) from Waste Polyethylene Terephthalate Plastic As a High-Performance Anode for Lithium-Ion Battery Applications.

The recycling of discarded polyethylene terephthalate (PET) plastics produced metal-organic frameworks can effectively minimize environmental pollution and promote sustainable economic development. In this study, we developed a method using NaOH in alcohol and ether solvent environments to degrade PET plastics for synthesizing terephthalic acid. The method achieved a 97.5% degradation rate of PET plastics under a reaction temperature of 80 °C for 60 min. We used terephthalic acid as a ligand from the degradation products to successfully synthesize two types of monometallic and bimetallic CoZn-MOF materials. We investigated the impact of different metal centers and solvents on the electrochemical performance of the MOF materials. The result showed that the MOF-DMF/H2O material maintained a specific capacity of 1485.5 mAh g-1 after 100 cycles at a current density of 500 mA g-1, demonstrating excellent rate capability and cycling stability. In addition, our finding showed that the performance difference might be attributed to the synergistic effect of bimetallic Co2+ and Zn2+ in MOF-DMF/H2O, rapid lithium-ion diffusion and electron transfer rates, and the absence of coordinating solvents. Additionally, the non-in situ X-ray powder diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis results showed that lithium storage in the MOF-DMF/H2O electrode mainly depended on the aromatic C6 ring and carboxylate portions of the organic ligands in different charge and discharge states. Lithium ions can be reversibly inserted/removed into/from the electrode material. The physical adsorption on the MOF surface through electrostatic interactions enhanced both capacity and cycling stability. This research provides valuable insight for mitigating solid waste pollution, promoting sustainable economic development, and advancing the extensive applications of MOF materials in lithium-ion batteries.

Sorption behavior of three aromatic acids (benzoic acid, 1-naphthoic acid and 9-anthroic acid) on biochar: Cosolvent effect in different liquid phases

Influence of the cosolvent on the sorption of organic acids on biochar has not been well understood. For this purpose, the sorption (log Km, L kg−1) of three aromatic acids (benzoic acid (BA, pKa = 4.20), 1-naphthoic acid (1-NAPA, pKa = 3.70), and 9-anthroic acid (9-ANTA, pKa = 3.65) was evaluated as a function of methanol volume fraction (fc = 0.0, 0.25, and 0.5), liquid pH (2.5 and 7.0), ionic composition (CaCl2 and KCl) and ionic strength (0.005 M, 0.5 M, and 1 M CaCl2). A giant Miscanthus-derived biochar (ZPC of 2.86) was used as the sorbent. For all solutes, the sorption coefficients (log Km) measured at pH 2.5 (i.e., pH < pKa) tended to decrease with increasing fc, as expected from the cosolvency model, while the result obtained at pH 7.0 was not fully explained by the same model. The log Km of 1-NAPA in the CaCl2 system was always greater than in the KCl system (p < 0.05) and the impact became pronounced at high pH (>pKa) with increasing fc. Increasing the Ca2+ concentration at fc = 0.0 (from 0.005 M to 1 M) enhanced the value by 0.32 log unit of Km. These phenomena indicate a significant role of dissolved Ca2+ in the liquid phase, most likely due to the formation of cation bridges between aromatic carboxylates and the biochar surface (i.e., [R-COO--Ca2+]-{Biochar−}). A decrease in the dielectric constant of the methanol mixture could fortify the formation of this bridge. Regardless of the degree of cosolvency power (σ), as the number of aromatic rings of solutes increases, Km decreases in the order BA > 1-NAPA > 9-ANTA, where fc = 0.0. In conclusion, the sorption potential of biochar can be significantly weakened by increasing pH and fc, and in the absence of a divalent cation.

Linker-length dependency of unsaturated Ni-oxo clusters in metal hydroxide-organic framework for photocatalytic CO2 reduction

A series of two-dimensional (2D) Ni-based metal hydroxide-organic frameworks (Ni-MHOFs), where hydroxide sheets crosslinked using aromatic carboxylate linkers, were studied for photo-driven CO2 reduction to CO. The molar ratio of metal to ligand in Ni-MHOFs was analysed to estimate coordinatively unsaturated Ni-oxo sites based on inductively coupled plasma (ICP) of metal Ni and 1H NMR of ligands. Photoluminescence quenching of Ru-based photosensitizer (PS) was measured to understand photoelectron transfer mechanism. Ni-MHOF with the longest ligand afforded more accessible unsaturated Ni-oxo catalytic sites, which promoted the photoelectron transfer from PS to catalyst and then engendered better CO evolution performance. This work demonstrates the linker-length dependencies of metal-oxo clusters in 2D MOFs, which suggests a way to modulate the coordinative environment of catalytic sites to fulfill efficient photocatalysis.

Gold-Catalyzed C-O Cross-Coupling Reactions of Aryl Iodides with Silver Carboxylates.

We have developed a C-O cross-coupling reaction of (hetero)aryl iodides with silver carboxylates via a AuI/AuIII catalytic cycle. The transformation featured exclusive chemoselectivity and moisture/air insensitivity. Aromatic and aliphatic (including primary, secondary, and tertiary) silver carboxylates are all suitable substrates. Moreover, this protocol worked well intermolecularly and intramolecularly. Most importantly, good yields were obtained regardless of the substrates' electronic effect and steric hindrance.

Ionic Liquids and Electrolytes with Flexible Aromatic Anions.

Five new n-tetrabutylphosphonium (P4444 )+ cation-based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 °C), phase behaviour (Tg <-55 °C) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.

A Joint Study of Experimental and Computational Chemistry to Probe the Effect of Coordination Modes on the Luminescence of Uranyl‐Organic Coordination Polymers

AbstractDespite the potential application of uranyl‐organic coordination polymers (UOCPs) in detecting metal cations and radiation rays, their luminescence properties have not been sufficiently studied at the molecular level. Herein, we synthesized a series of UOCPs (UOCP1–9) with new construction based on bipyridinium salts and diverse auxiliary ligands. The physicochemical properties of the complexes with high purity were systematically characterized, especially the luminescence spectra. A deep theoretical investigation was conducted to illustrate the relation between uranyl coordination and the luminescence spectral property. The results show that the influence of ligand type on the uranyl luminescent spectral properties increases in the order of hydroxide&gt;oxalate&gt;aromatic carboxylate, which can be attributed to the magnitude of orbital interaction between uranyl and ligand. This work helps to profoundly understand uranyl optical properties and electronic structure at the molecular level, providing important hints for recognizing the nature of luminescent spectral features of uranyl‐containing materials, as well as the fundamental chemistry of actinide elements.

Density Functional Theory Guided Investigation of Ligand‐Induced Neptunyl‐Neptunyl Interactions

AbstractActinyl‐actinyl interactions are particularly prevalent for the pentavalent neptunyl cation (Np(V)O2)+where these interactions appear either as aT‐ orD‐shape (diamond‐shape).T‐shaped interactions have been previously identified in high concentration Np(V) solutions containing simple anions (NO3−, ClO4−, Cl−) whereasD‐shaped have only been isolated in the solid‐state in the presence of carboxylate ligands. In this study, Density Functional Theory (DFT) calculations were paired with Raman spectroscopy to evaluate the formation ofD‐shaped interactions in the presence of aliphatic (R=H (formate), CH3(acetate), CH2CH3(propionate)) and aromatic (R=C6H5(benzoate), C6H4OH (4‐hydroxybenzoate), C5H4N (isonicotinate)) carboxylate ligands. DFT studies indicate that the ΔGto form hydratedT‐ andD‐shaped forms are not spontaneous but become so with the addition of the carboxylate ligands. Raman spectra of the Np(V) carboxylate solutions contained vibrational modes associated with theD‐shaped interactions, but spectral changes observed over time indicate a dynamic system. Crystallization experiments from the Np(V) carboxylate systems confirmed the presence ofD‐shaped dimers for the aromatic carboxylates, suggesting that the choice of the anion in solution favors actinyl‐actinyl interactions even at low concentrations (≤20 mM) of Np(V).

Effect of the substituted location on luminescent behaviors with Ambroxol moieties: Synthesis, crystal structure and Hirshfeld surface

To further exploit the new materials, a set of new salts containing ambroxol and hydroxyl aromatic carboxylate moieties, namely, [HAXE]+B– (B = MSA (1), 23A (2) and 26A (3)) [AXE = 4-((2-amino-3,5-dibromobenzyl)amino) cyclohexan-1-ol, MSA = 5-methyl salicylic acid, 23A = 2‑hydroxy-3-naphthoic acid, and 26A = 2‑hydroxy-6-naphthoic acid], were obtained by the reaction of AXE and a set of aromatic carboxylic acid, respectively. The emission maxima can be found at 386, 445, 523 and 452 nm for AXE and its compounds 1–3 in the solid state at room temperature, respectively. Compared with the free AXE, the emission maxima of compounds 1–3 are obviously red-shifted about 59, 137 and 66 nm, respectively, revealing that the intermolecular packing interactions affect the emission maxima. Compounds 1–4 were structurally characterized by X–ray single crystal diffraction and FT-IR. Single crystal X-ray diffraction analysis shows that there exist π⋯π packing interactions and a set of hydrogen bonds. The shortest distances of π⋯π stacking interactions are 3.693(6) and 3.86(2) Å in compounds 2 and 3, respectively. The Hirshfeld surface analysis reveals that the order of the C···H/H···C close contacts coincides with that of the luminescent maxima. Meanwhile, the intermolecular contacts of O···H/H···O and N···H/H···N can quantitatively account for the melting points of these compounds. Additionally, the thermal properties of compounds 1–3 were estimated in detail.

Spectroscopic Characterization of the Divalent Metal Docking Motif to Isolated Cyanobenzoate: Direct Observation of Tridentate Binding to ortho-Cyanobenzoate and Implications for the CN Response

Cryogenic ion vibrational spectra of D2-tagged cyanobenzoate (CBA) derivatives are obtained and analyzed to characterize the intrinsic spectroscopic responses of the -CO2- headgroup to its location on the ring in both the isolated anions and the cationic complexes with divalent metal ions, M2+ (M = Mg, Ca, Sr). The benzonitrile functionality establishes the different ring isomers (para, meta, ortho) according to the location of the carboxylate and provides an additional reporter on the molecular response to the proximal charge center. The aromatic carboxylates display shifts slightly smaller than those observed for a related aliphatic system upon metal ion complexation. Although the CBA anions display very similar band patterns for all three ring positions, upon complexation with metal ions, the ortho isomer yields dramatically different spectral responses in both the -CO2- moiety and the CN group. This behavior is traced to the emergence of a tridentate binding motif unique to the ortho isomer in which the metal ions bind to both the oxygen atoms of the carboxylate group and the N atom of the cyano group. In that configuration, the -CO2- moiety is oriented perpendicular to the phenyl ring, and the CN stretching fundamental is both strong and red-shifted relative to its behavior in the isolated neutral. The behaviors of the metal-bound ortho complexes occur in contrast to the usual blue shifts associated with "Lewis" type binding of metal ions end-on to -CN. The origins of these spectroscopic features are analyzed with the aid of electronic structure calculations, which also explore differences expected for complexation of monovalent cations to the ortho carboxylate. The resulting insights have implications for understanding the balance between electrostatic and steric interactions at metal binding sites in chemical and biological systems.

Light-controlled detection of aromatic carboxylate anions using doubly fused naphthopyran derivative

A photochromic naphthopyran derivative, 2,2,11,11-tetraphenyl-2,11-dihydrobenzo[f]pyrano[3,2-h]chromene has been synthesized and its structure was confirmed using various spectroscopic techniques like NMR, infrared spectroscopy (FT-IR), high-resolution mass spectroscopy (HR-MS) and single crystal X-ray diffraction (SCXRD). The synthesized probe has shown a sensitive signal toward salicylic acid and 3,5-diaminobenzoic acid in acetonitrile: water (50:50(v:v)) solvent system at pH 7.6 (1 mM Tris buffer). UV–vis and fluorescence spectroscopic analyses revealed complex formation between these carboxylate anions and the synthesized photochromic probe, with blue shifts in absorption bands & enhancement in fluorescence intensity. Furthermore, photo-switching for the naphthopyran derivative in presence of both carboxylic acids was performed using 365 nm UV light, and results obtained indicated that the release and binding of these carboxylic acids can be controlled using 365 nm UV light. As expected, the fluorescence analysis provided a better limit of detection value as compared to the UV–Vis analysis. Fluorescence spectroscopy yielded a detection limit of 16.29 nM for salicylate ions using the naphthopyran-based probe.

Особенности термолиза ароматических карбоксилатов Cr (III)

The article discusses the main methods for obtaining carbon composite nanomaterials and highlights the thermolysis method as one of the main methods. To understand the essence of thermal decomposition processes as a method for synthesis of carbon nanomaterials, chromium (III) aromatic carboxylates have been considered. These are chromium (III) 8-hydroxyquinolinate, benzoate, salicylate, phthalate, and p-aminobenzoate. The article thoroughly discusses the procedure for the synthesis of these chromium (III) carboxylates from the most common inorganic chromium (III) salts under simple conditions. The thermal decomposition process was carried out in two environments (in oxidizing air and neutral argon), the obtained products were compared. For a detailed study of the processes of decomposition of chromium (III) carboxylates, thermal analysis methods (TG and DSC) were used on a Netzsch 449 Jupiter synchronous thermal analyzer. To study the morphology and composition of the products, the methods of X-ray phase analysis, optical and scanning electron microscopy, and X-ray fluorescence microanalysis were used. We used a Rigaku Ultima IV X-ray diffractometer and a scanning electron microscope with a Jeol JSM-7001F elemental microanalysis attachment. On the basis of the obtained results, the estimated formulas of the initial chromium (III) carboxylates were calculated. The mechanisms of the processes occurring during the thermal decomposition of chromium (III) aromatic carboxylates were also proposed. For a more accurate determination of the composition of the synthesized chromium (III) carboxylates and a more accurate description of the processes of thermal decomposition of these salts, the corresponding aromatic carboxylic acids were also subjected to thermal decomposition. The appendix to the article contains all the obtained data for a more accurate interpretation of the results and a more detailed description of the thermal decomposition processes.

Construction of ZnII/CdII-based MOFs containing a tripodal aromatic carboxylate ligand with unequal arms and their fluorescence detection for Cu2+ and Fe3+ cations

Four MOFs have been synthesized and characterized. The luminescent sensing investigation indicates that compound 1 exhibits extremely sensitive and selective detection of Cu2+ and compounds 2–4 show extremely sensitive and selective detection of Fe3+.