Isophthalic Acid Research Articles

Upcycling of Polystyrene to Aromatic Polyacids by Tandem Friedel-Crafts and Oxidation Reactions.

Due to the high demand and the increasing production rate of plastic materials, vast amounts of wastes are generated every year. An important fraction of these wastes contain polystyrene (PS), which is seldom recycled, neither mechanically nor chemically. While several chemical recycling strategies have been developed, they are either very energy-demanding or produce chemicals that can hardly be employed in the synthesis of plastics (e.g., benzene and benzoic acid). Here, we report the upcycling of PS waste into aromatic polyacids, useful in polyester synthesis, such as polyethylene terephthalate (PET). To this end, a conventional Friedel-Crafts acylation was first investigated, to produce an acylated PS chain, using acetic anhydride and stoichiometric amounts of AlCl3. As a catalytic alternative, the alkylation of PS was studied, using InCl3 and isopropyl acetate. The acylated and alkylated PS samples were then oxidized to produce terephthalic (TA), isophthalic (IPTA), benzoic (BA), and trimesic (TMA) acid.

Fabrication of Co(II)-based coordination polymer for photocatalytic degradation: Selective removal of cationic methyl violet dye

In this study, a new coordination polymer (CP) was designed and synthesized to evaluate the photocatalytic properties for water remediation. The Co(II)-based CP {[Co(HL)(bid)(H2O)]·2H2O}n (1) was hydrothermally synthesized using the ligand 5-(4′-carboxyphenoxy)isophthalic acid (H3L) and 1,4-bis(1-imidazolyl)-2,5-dimethylbenzene (bid). The coordination polymer (1) has been characterized by various spectral techniques, thermogravimetric (TGA), and single crystal X-ray technique. X-ray data revealed that (1) exhibits 2D framework having an octahedral coordination geometry around the Co(II) ions, having μ1:η1-η1 mode with chromophore CoO4N. FT-IR analysis confirmed the asymmetric monodentate binding modes of the carboxylate ligand. The CP 1 has demonstrated optical semiconducting properties, rendering them promising candidates for photocatalytic applications. The catalyst (1) has been effectively utilized in the breakdown of several organic dyes, such as methylene blue (MB), methyl orange (MO), methyl violet (MV), and rhodamine B (RhB). The results showed that at pH 4, with a dosage of 30 mg of catalyst (1), 92.08 % of MV was degraded at a concentration of 20 ppm. Additionally, the mechanistic pathway for light-driven MV decomposition was investigated through experimental approaches, specifically radical trapping experiments.

Stoichiometry-Regulated Synthesis of Three Adenine-Based Coordination Polymers for Catalytic Excellence through the Synergistic Amalgamation of Coordinative Unsaturation and Lewis Basic Sites.

Nucleobase adenine is a promising candidate for synthesizing fascinating coordination polymers (CPs) due to the presence of five potential metal-ion binding centers. In recent years, CPs have emerged as promising Lewis acid-base centers containing heterogeneous catalysts for a wide range of organic transformations. However, the crucial role of stoichiometric regulations of the starting materials and their consequential impact on catalytic performance are rarely studied. Herein, we have synthesized three adenine (Ad)-based cadmium CPs with 5-nitro isophthalic acid (H2NIPA) by a mixed linker approach by tuning the substrate's stoichiometric proportion. The single-crystal X-ray diffraction analysis of the synthesized CPs, SSICG-11, [Cd(Ad)(NIPA)(H2O)]·H2O; SSICG-12, [Cd(Ad)2(NIPA)(H2O)]; and SSICG-13, [Cd4(Ad)(NIPA)3]·H2O·DMF, reveals that these three compounds exhibit distinct asymmetric units, each reflecting varying precursor proportions. Due to their high chemical stability and the presence of both Lewis acidic-basic sites, SSICG-11-13 were employed as heterogeneous catalysts for Hantzsch and Strecker reactions. However, SSICG-12 is more efficient due to its capacity to form an open metal sites (OMSs) and the presence of a higher number of adenine moieties. Overall, this study demonstrated the stoichiometrically controlled synthesis of adenine-based CPs and dissected their efficiency as a heterogeneous catalyst by correlating their structures and compositions.

Preparation and solid-state characterization of two novel berberine chloride cocrystals with benzene derivatives

In this study, two novel salt-cocrystals of berberine chloride (BCl) with structurally similar benzene derivatives, i.e., 3-hydroxybenzoic acid (3HBA) and isophthalic acid (IA), were prepared. Their solid-state properties were characterized by complementary techniques, including single-crystal and powder X-ray diffractometry, thermogravimetric-differential scanning calorimetry, Fourier-transformed infrared spectroscopy, and dynamic moisture sorption analysis. Both cocrystals had lower hygroscopicity than BCl. An analysis of the properties of these cocrystals along with a previously published berberine chloride-resorcinol cocrystal suggests that a greater number of hydroxyl groups in these cocrystal formers may favor faster dissolution, measured by both intrinsic dissolution rate and powder dissolution.

Predicting the Thermodynamic Solubility and Stability of Co-crystals and Eutectics of Febuxostat by using a Thermodynamic Model involving Flory Huggins Interaction Parameter.

A method is presented for determining the thermodynamic (equilibrium) solubility of a drug in coformer for the non-covalent derivative (NCD) systems i.e. eutectics/co-crystals. The method is based on a thermodynamic model to calculate the Gibbs energy change ∆GCC associated with forming a drug-coformer NCD system. This model includes contributions from heat capacity differences between the mixed and unmixed components, breaking up of the solid drug and coformer lattice structure, and drug ─ coformer mixing. Calculation of ∆GCC from thermal analysis data is demonstrated, and the equilibrium drug solubility in coformer is represented by minima of plots of ∆GCC versus the dissolved drug fraction(f1). Eight (8) coformer molecules, namely, 1-hydroxy 2-naphthoic acid (1H-2NPH), 4-hydroxy benzoic acid (4-HBA), salicylic acid (SLC), 4-amino salicylic acid (4-ASA), 5-nitro isophthalic acid (5N-IPH), pyrazinamide (PZD), isonicotinamide (ISNCT), and picolinamide (PICO) were used for the formation of NCDs of a highly water insoluble drug febuxostat (FXT). The importance of heat capacity and interaction parameter in determining the solubility behavior of drug-coformer in the formed NCDs was discussed. Further, ∆GCC for FXT in selected NCDs were plotted as a function of composition and temperature to determine the thermodynamic stability over the range of room temperature to formulation melting. It was concluded that the thermodynamic model can reasonably predict the maximum stable drug loading in a multi-crystalline system at a particular temperature, and serve as a complementary screening tool in determining the best stoichiometric ratio of the drug and coformer in terms of solubility and thermodynamic stability.

A multifunctional Eu-organic framework for fluorescence sensing properties and the detection of pyrimethanil in real samples

Europium metal–organic frameworks (Eu-MOFs) have unique application prospects in the field of fluorescence sensing, due to the fluorescence characteristics of Eu3+ ion and organic ligands, and the advantages of obvious red luminescence, long emission lifetime, large Stokes shift, and high quantum yield. In this study, a novel Eu-MOF was synthesized hydrothermally using europium acetate hexahydrate (Eu(Ac)3·6H2O), 5-(4′-carboxybenzyloxy) isophthalic acid (5-H3CIA), and 4,4′-bipyridine (4,4′-bipy). Structural analysis revealed that the Eu-MOF exhibited a three-dimensional framework with 4,4′-bipyridine as the guest molecule. Fluorescence sensing experiments revealed that 2,4,6-trinitrophenol, ornidazole, pyrimethanil, and Cr2O72− effectively quenched the fluorescence of the Eu-MOF in aqueous solution, with corresponding limits of detection as low as 0.886, 0.732, 0.569, and 2.800 μM, respectively. Exploiting the ability of Cr2O72− to quench the fluorescence of the Eu-MOF, we devised a Cr2O72−@Eu-MOF fluorescence silencing system that, in the presence of ascorbic acid, gradually recovered its fluorescence to form a unique fluorescence “on–off-on” sensor. In addition, the fluorescence sensing mechanism of Eu-MOF was studied, the fluorescence test was prepared to detect Cr2O72− with an open eye, and the content of pyrimethanil was detected in real samples, including cucumber skin, tomato skin, grape skin, apple and kiwi.

Storehouse of Peculiar Supramolecular Architecture: Probing the Charge-Transfer Phenomenon and Effect of Altering the pH in a Meta-Oriented Single Donor-Double Acceptor Fluorophore.

The investigation of excited-state intramolecular charge transfer (ESICT) has been a fascinating area of research. Although the ESICT events have been studied mostly for para-disubstituted donor-acceptor type molecules, the meta-oriented donor-acceptor type molecules have also shown tremendous potential as ESICT active molecules. In the current work, a small fluorescent probe diethyl 5-amino isophthalate (DE-5A-IPA) was investigated as a potential model to investigate ESICT events in the solution as well as solid phase. DE-5A-IPA was synthesized easily starting from commercially available 5-amino isophthalic acid in excellent yield. In the solid state, differing extents of CH···π-type binding led to formation of fully planar and puckered "cyclobutane" mimic supramolecular architecture, as evidenced from the crystal structure analysis. In addition, the single crystal structure of DE-5A-IPA shows that the donor (-NH2) and acceptor (-CO2Et) are situated in the same plane, thereby assuring the prerequisites of a through-space charge transfer. DE-5A-IPA undergoes noticeable Stokes shift (in cm-1) when the polarity of the medium was changed (4820 cm-1 in hexane; 9375 cm-1 in water). The excited-state dipole moment (μe) was calculated to be 4.0 units higher than the ground-state dipole moment (μg). DE-5A-IPA had an appreciable quantum yield (0.10 ± 0.03 to 0.27 ± 0.04). The ESICT phenomenon was also investigated by ground- and excited-state structural calculations using Gaussian 16 software. The excited-state lifetime measured by the time correlated single photon counting technique was found to vary with the polarity of the solvent, thereby providing further support to the ESICT phenomenon being operative in DE-5A-IPA. Taking advantage of the -NH2 group (which is susceptible to protonation) in DE-5A-IPA, steady state and time-resolved photodynamics were investigated in solutions of varying pH values. Interestingly, the emission quantum yields as well as the emission lifetime increase with an increase in pH value, thereby establishing DE-5A-IPA as a pH-sensitive probe. The current findings shall boost the understanding of meta-oriented ESICT enabled compounds in terms of their excited-state photophysics.

Two-Dimensional MOF Constructed by a Binuclear-Copper Motif for High-Performance Electrocatalytic NO Reduction to NH3.

Ambient electrochemical NO reduction presents a dual solution for sustainable NO reduction and NH3 synthesis. However, their complex kinetics and energy demands necessitate high-performance electrocatalysts to ensure effective and selective process outcomes. Herein, we report that a two-dimensional Cu-based metal-organic framework (MOF), {[Cu(HL)]·H2O} n , (Cu-OUC, H3L = 5-(2'-carboxylphenoxy)isophthalic acid) acts as a stable electrocatalyst with high efficiency for NO-to-NH3 conversion. Electrochemical experimental studies showed that in 0.1 M K2SO4 solution, the as-prepared Cu-OUC achieved a peak Faradaic efficiency of 96.91% and a notable NH3 yield as high as 3415.82 μg h-1 mg-1. The Zn-NO battery in aqueous solution can produce electricity possessing a power density of 2.04 mW cm-2 while simultaneously achieving an NH3 yield of 616.92 μg h-1 mg-1. Theoretical calculations revealed that the surface of Cu-OUC effectively facilitates NO activation through a two-way charge transfer mechanism of "electron acceptance and donation", with the *NO formation step being the potential-determining stage. The study pioneers the use of a MOF as an electrocatalyst for ambient NO-to-NH3 conversion.

Seasonal variation and size distribution of aromatic acids in urban aerosols in Beijing, China

Aromatic acids are an integral component of organic acids in the atmosphere, contributing to the formation of climate-altering brown carbon (BrC). To better understand the sources and formation processes of aromatic acids, we collected size-segregated particulate matter samples in urban Beijing from April 2017 to January 2018, which were analyzed using solvent-extraction followed by gas chromatography/mass spectrometry. Phthalic acid (o-PhA) had the greatest average annual concentration, followed by terephthalic acid (p-PhA), 4-hydroxybenzoic acid (4-OHBA), dehydroabietic acid (DA), syringic acid (SA), 3-hydroxybenzoic acid (3-OHBA), isophthalic acid (m-PhA), and vanillic acid (VA). We identified distinct seasonal variations in aromatic acids, with o-PhA peaking in summer due to photochemical activity, while p-PhA and 4-OHBA elevated in autumn and summer, respectively, influenced by open waste and biomass burning. Wintertime variations in all aromatic acids were driven by complex meteorology and increased anthropogenic emissions, including rural biomass burning for cooking and heating. Particle size distribution of aromatic acids was affected by seasonal agricultural activities and dust storms, multiple emission sources, and formation mechanisms. The o-PhA has predominantly bimodal distribution, with diverse sources and complex formation mechanisms including gas- and aqueous-phase chemistry. The applicability of o-PhA as a tracer for specific secondary organic aerosols has been questioned due to its potential primary sources. The 3-OHBA, 4-OHBA, VA, SA, and DA exhibited bimodal or trimodal patterns during haze and non-haze periods across different particle size ranges. The seasonal variation in VA/SA and VA/4-OHBA ratios demonstrated the complexity of biomass burning types, influenced by season, particle size, meteorological conditions, and combustion sources.

A Magnesium Organic Framework Fluorescent Sensor for Selective Detection of Nitrofuran Antibiotics and Inorganic Pollutants

ABSTRACTA novel 3D magnesium‐based metal organic framework (Mg‐MOF) has been solvothermally synthesized using 5‐(pyridin‐4‐yl)isophthalic acid. The ligand has demonstrated to preserve two types of coordination modes depending on the connection mode of the pyridine group. The uncoordinated pyridine groups provide Lewis base sites (LBSs), whereas the coordinated ones promote to form a rarely reported eight‐connected tetranuclear Mg clusters. Benefiting from the multinuclearity with high number of connections, the framework keeps good performance of high thermal stability until 500°C. Furthermore, the framework exhibits potential open metal sites (OMSs) benefiting from the terminal coordinated water groups of the metal clusters. Owing to the abundant active sites, the Mg‐MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72−, with high KSV (at 104 M−1 level) and low limit of detection (LOD) values (∼10−6 M). Density functional theory (DFT) investigation reveals that the interchange of the HOMO–LUMO energy levels of the framework and antibiotics is responsible for the sensing activity. In addition, the Mg‐MOF is greatly recyclable in five cycles while maintaining the structural rigidity and sensing activity, making it a promising luminescence probe material.

Ultrasonic synthesis, characterization, DFT and molecular docking of a biocompatible Zn-based MOF as a potential antimicrobial, anti-inflammatory and antitumor agent

Zinc metal–organic frameworks have emerged as promising candidates, demonstrating excellent biological properties stemming from the unique characteristics of MOFs and zinc. In this study, we employed a facile method to synthesize a zinc metal–organic framework [Zn(IP)(H2O)] using ultrasound irradiation, with the linker being isophthalic acid (IPA) (1,3-benzene dicarboxylic acid). The parent Zn-MOF and two Ag/Zn-MOF samples prepared via loading and encapsulation methods were comprehensively characterized using various techniques, including FT-IR, XRD, SEM, TEM, N2 adsorption–desorption isotherm, UV–vis spectroscopy and TGA. The parent Zn-MOF and two Ag/Zn-MOF samples exhibited a broad spectrum of antibacterial effects. Remarkably, genomic DNA of P. aeruginosa was effectively degraded by Zn-MOF, further supporting its potent antibacterial results. The free radical inhibition assay demonstrated a 71.0% inhibition under the influence of Zn-MOF. In vitro cytotoxicity activity of Zn-MOF against HepG-2 and Caco-2 cell lines revealed differential cytotoxic effects, with higher cytotoxicity against Caco-2 as explored from the IC50 values. This cytotoxicity was supported by the high binding affinity of Zn-MOF to CT-DNA. Importantly, the non-toxic property of Zn-MOF was confirmed through its lack of cytotoxic effects against normal lung cell (Wi-38). The anti-inflammatory treatment of Zn-MOF achieved 75.0% efficiency relative to the standard Ibuprofen drug. DFT and docking provided insights into the geometric stability of Zn-MOF and its interaction with active amino acids within selected proteins associated with the investigated diseases. Finally, the synthesized Zn-MOF shows promise for applications in cancer treatment, chemoprevention, and particularly antibacterial purposes.

Structural Landscape and Proton Conduction of Lanthanide 5-(Dihydroxyphosphoryl)isophthalates.

Metal phosphonate-carboxylate compounds represent a promising class of materials for proton conduction applications. This study investigates the structural, thermal, and proton conduction properties of three groups of lanthanide-based compounds derived from 5-(dihydroxyphosphoryl)isophthalic acid (PiPhtA). The crystal structures, solved ab initio from X-ray powder diffraction data, reveal that groups Ln-I, Ln[O3P-C6H3(COO)(COOH)(H2O)2] (Ln = La, Pr), and Ln-II, Ln2{[O3P-C6H3(COO)(COOH)]2(H2O)4}·2H2O (Ln = La, Pr, Eu), exhibit three-dimensional frameworks, while group Ln-III, Ln[O3P-C6H3(COO)(COOH)(H2O)] (Ln = Yb), adopts a layered structure with unbonded carboxylic groups oriented toward the interlayer region. All compounds feature carboxylic groups and coordinating water molecules. Impedance measurements demonstrate that these materials exhibit water-mediated proton conductivity, initially following a vehicle-type proton-transfer mechanism. Upon exposure to ammonia vapors from a 14 or 28% aqueous solution, compounds from groups II and III adsorb ammonia and water, leading to an enhancement in proton conductivity consistent with a Grotthuss-type proton-transfer mechanism. Notably, group II of the studied compounds undergoes the formation of a new expanded phase through the internal reaction of carboxylic groups with ammonia, coexisting with the as-synthesized phase. This postsynthetic modification results in a significant increase in proton conductivity, from approximately ∼5 × 10-6 to ∼10-4 S·cm-1 at 80 °C and 95% relative humidity (RH), attributed to a mixed intrinsic/extrinsic contribution. Remarkably, the NH3(28%)-exposed Yb-III compound achieves an enhancement in proton conductivity, reaching ∼ 5 × 10-3 S·cm-1 at 80 °C and 95% RH, primarily through an extrinsic contribution.

A stable 2D Cd (II) coordination polymer based on mixed ligands as a fluorescence sensor for detection of tetracycline antibiotic in milk and honey

An innovative two-dimensional Cd (II) coordination polymer, namely, [Cd(L)(dibp)] (CP 1) (dibp= 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl; H2L= 5-(1-oxoisoindolin-2-yl)isophthalic acid), have been successfully synthesized under solvothermal condition and characterized by X-ray single crystal diffraction, PXRD, IR, TGA, elemental analysis and solid-state fluorescence analysis. Single-crystal X-ray structural analysis suggests that CP 1 crystallizes in monoclinic system with a space group of P21/c and displays a 2D layer based on centrosymmetric binuclear [Cd2(CO2)4N4] units. Sensing experiments have shown that CP 1, as an emerging fluorescent sensor, can selectively, sensitively and quickly detect Tetracycline antibiotic (TC) with fantastic reusability and low detection limit (LOD = 0.092 μM). At the same time, the fluorescence quenching mechanism of CP 1 may be the FRET and PET. Excitingly, CP 1 as a novel fluorescent sensor can detect TC in milk and honey with recovery rates of 96.8–101.2 % and 97.2–100.8 %, respectively.

Brightening triplet excitons enable high-performance white-light emission in organic small molecules via integrating n–π*/π–π* transitions

Luminescent materials that simultaneously embody bright singlet and triplet excitons hold great potential in optoelectronics, signage, and information encryption. However, achieving high-performance white-light emission is severely hampered by their inherent unbalanced contribution of fluorescence and phosphorescence. Herein, we address this challenge by pressure treatment engineering via the hydrogen bonding cooperativity effect to realize the mixture of n–π*/π–π* transitions, where the triplet state emission was boosted from 7% to 40% in isophthalic acid (IPA). A superior white-light emission based on hybrid fluorescence and phosphorescence was harvested in pressure-treated IPA, and the photoluminescence quantum yield was increased to 75% from the initial 19% (blue-light emission). In-situ high-pressure IR spectra, X-ray diffraction, and neutron diffraction reveal continuous strengthening of the hydrogen bonds with the increase of pressure. Furthermore, this enhanced hydrogen bond is retained down to the ambient conditions after pressure treatment, awarding the targeted IPA efficient intersystem crossing for balanced singlet/triplet excitons population and resulting in efficient white-light emission. This work not only proposes a route for brightening triplet states in organic small molecules, but also regulates the ratio of singlet and triplet excitons to construct high-performance white-light emission.

Poly(1,12-dodecylene 5,5′-isopropylidene-bis(ethyl 2-furoate))-based sulfonated copolyesters: Effect of ionic groups and long chain aliphatic spacer on their thermo-mechanical properties, hydrodegradability and liquid water sorption

Poly (1,12-dodecylene 5,5′-isopropylidene-bis(ethyl 2-furoate)) has recently been introduced to the polymer field as an exceptionally flexible polyester derived from bio-based and cost-effective monomers. A partially sulfonated version of this polymer is prepared in this study by copolymerization with sulfonated isophthalic acid. A series of sulfonated bisfuranic-aromatic copolyesters PDDbFXSIY, containing up to 50 mol% of sulfonated moieties was synthesized, for the first time, using the 1,12-dodecandiol as a comonomer. Their chemical structure was investigated by FTIR and NMR (1H and 13C) spectroscopy. In terms of properties, these copolyesters showed high thermal stability (c.a. Td,max ≥ 350 °C), a low glass transition temperature and they were found to be amorphous up to 20 mol% of the sulfonated unit content. Hydrodegradability tests on PDDbFXSIY films carried out under alkaline conditions revealed highly stable materials even with increasing amount of sulfonated units. In addition, the films exhibit good liquid water sorption, which increases as the amount of sulfonated groups decreases, following the opposite trend of previously reported sulfonated bisfuranic-aromatic copolyesters prepared using short-aliphatic chain diols. These properties are obviously related to the concurrently incorporation of a dodecylene chain and sulfonated groups in the same backbone, making it possible to generate new hydrolytically stable bisfuran-based polymers with a sorption feature.

Constructing a 3D Zinc metal-organic framework for ratiometric and selectively PO43− sensing and catalyzing CO2 chemical fixation

Architecting a metal-organic framework (MOF) with functions of ratiometric phosphate ion (PO43−) sensing and catalytically transforming CO2 into high-value-added chemicals is of great significance but also challenging. In this work, we designed and constructed a zinc MOF, namely {[Zn3(Dipa)2.5(nia)3⋅H2O]⋅4H2O}n (Zn-DN), based on 3, 6-di(1H-imidazol-1-yl)pyridazine (Dipa) and 5-(1, 8-naphthalimido)-isophthalic acid (H2nia), which presents a 3D porous and (3, 4)-connected {42·6·83}2{42·6} network. Zn-DN exhibits thermal stability, good solvent stability, and a wide scope of pH tolerance (2.0–12.0). Fluorescent spectra studies show that Zn-DN can be explored as a ratiometric fluorescence sensor for PO43− in water, with high selectivity, sensitivity (LOD of 0.27 μM), rapidness (< 1 min), and good reusability (10 cycles). Moreover, the opened zinc nodes of Zn-DN act as active Lewis acid sites and allow it to catalyze the chemical fixation of CO2 with various epoxides (7 examples) under solvent-free conditions, achieving high conversion (90–99 %) and selectivity (92–99 %). Zn-DN can be regenerated and reused 10 times without marked loss in its catalytical activity.

Chiral Ca–Mn-frameworks with double helical chains and one-dimensional channels constructed from enantiomorphous lactate synthons

Under solvothermal synthetic condition, lactate derivatives (R)-5-(1- carboxyethoxy)isophthalic acid ((R)-H3CIA) and (S)-5-(1-carboxyethoxy)isophthalic acid ((S)–H3CIA) assembled with Ca(Ⅱ) and Mn(Ⅱ) ions to obtain enantiomers {[MnCa0.5((R)-CIA)(H2O)]·((CH3)2NH2CH3CO2)0.5(H2O)}n (HU21-R) and {[MnCa0.5((S)-CIA)(H2O)]·((CH3)2NH2CH3CO2)0.5(H2O)}n (HU21–S), respectively. Complexes HU21-R and HU21–S belong to orthorhombic crystal system with chiral space group I212121. Single crystal X-ray diffraction analysis revealed that all oxygen atoms of synthons (R)-CIA3- and (S)-CIA3- participated in the coordination with metal ions. Thus, semi-rigid (R)-CIA3- and (S)-CIA3- anions become rigid linkers in HU21-R and HU21–S. Fragments of (R)-CIA3- anion are connected by Ca(Ⅱ) ions to build right-handed double helical chains in HU21-R, while the enantiomeric left-handed double helixes are constructed by (S)-CIA3- fragments and Ca(Ⅱ) ions in HU21–S. Additionally, Mn(Ⅱ) centers and CIA3− anions resulted in a rare 4,4,4-connected net with point symbol of (42.62.82)3(42.64). Ca(Ⅱ) ions were further filed into Mn-CIA-framework to form a three dimensional structure with one dimensional channel. Moreover, magnetic test indicates that the framework has a canted antiferromagnetic behavior.

Room-Temperature Persistent Phosphorescence of Aggregated Gold Nanoclusters under Molecular Crystal Confinements.

We report color-tunable and solvent-processable persistent fluorescence to phosphorescence switching at room temperature by doping gold nanoclusters (AuNCs) inside molecular crystals. This provides a significant insight into the tunability of the photoluminescence property of the dopant depending on the crystal environment and compactness of confinement, with the possibility of energy transfer from crystal to aggregated AuNCs. For test cases, we have doped histidine-stabilized AuNCs (HIS-AuNCs) inside histidine (HIS-AuNCs-HIS) and isophthalic acid (HIS-AuNCs-IPA) crystals, respectively, and glutathione-stabilized AuNCs (GSH-AuNCs) inside histidine crystals (GSH-AuNCs-HIS). The maximal phosphorescence decay time recorded for crystal doped aggregated AuNCs was 9.38 ms, and the photoluminescence quantum yield value was measured as 25%. The possible energy states and potential interactions between aggregated NCs and host crystals were accounted for through density functional theory calculations and docking techniques, respectively. This finding opens new possibilities for designing and producing color-tunable persistent AuNC-based luminous crystals for multilayer information encryption, display, and biological applications.

Fluorescent hydrogen-bonded organic framework act as a multifunctional platform for Fe3+ and F− sensing, and for information encryption

Due to their exceptional optical properties and adjustable functional characteristics, hydrogen-bonded organic frameworks (HOFs) demonstrate significant potential in applications such as sensing, information encryption. However, studies on the synthesis of HOFs designed to construct multifunctional platforms are scant. In this work, we report the synthesis of a new fluorescent HOF by assembling melem and isophthalic acid (IPA), designated as HOF-IPA. HOF-IPA exhibited good selectivity and sensitivity towards Fe3+, making it suitable as a fluorescent sensor for Fe3+ detection. The sensor achieved satisfactory recoveries ranging from 97.79 % to106.42 % for Fe3+ sensing, with a low relative standard deviation (RSD) of less than 3.33 %, indicating significant application potential for HOF-IPA. Due to the ability of F− to mask the electrostatic action on the surface of Fe3+ and inhibit the photoelectron transfer (PET) of HOF-IPA, the HOF-IPA − Fe3+ system can be utilized as a fluorescent “off–on” sensor for F− detection. Additionally, owing to the colorless, transparent property of HOF-IPA in aqueous solution under sunlight and its blue fluorescence property under UV light (color) or microplate reader (fluorescence intensity), HOF-IPA based ink can be used for various types of information encryption, and all yielding favorable outcomes.

Effect of structure on sensing performance of nitro explosives with high sensitivity and mechanism of two Tb(III) coordination polymers

The use of a conjugate N-containing ligand resulted in the decreasing of structural dimensions from 2D network of [Tb(2-pyia)(Ac)(H2O)] (CP1) to 1D chain [Tb(2-pyia)(Ac)(IDP)] (CP2) (2-H2pyia = 5-(pyridin-2-ylmethoxy) isophthalic acid and IDP=imidazo[4,5-f]-[1,10] phenanthroline). Both of them exhibit the characteristic luminescence of Tb ions and could have high fluorescence sensing properties for cefixime and fluridine. The different sensing properties for nitro explosives are manifested as CP1 for nitrobenzene and CP2 for 4-nitrophenol due to the difference in structure. Furthermore, CP2 exhibits the ratiometric fluorescence sensing for Fe3+ ion with a low detection limit of 0.405 μM. The fluorescence sensing mechanism of the two Tb complexes for different analytes was investigated using experimental methods and theoretical calculations. CP1 was used for the detection of Flu residues in the actual system and better results were obtained. The work shows the introduction of the chelated ligand might affect the structural and sensing performance changes of coordination polymers.