Lattice Water Molecules Research Articles

NH4Ca[B5O7(OH)4] H2O: A Biaxial Mixed‐Cation Pentaborate with Moderate Birefringence

AbstractAmmonium‐calcium mixed‐cation pentaborate NH4Ca[B5O7(OH)4]·H2O has been synthesized for the first time. Single‐crystal X‐ray diffraction analysis reveals that it crystallizes in the triclinic space group P‐1 with lattice parameters a = 6.7042(3) Å, b = 7.1859(3) Å, c = 10.7447(4) Å, α = 100.304(3), β = 97.774(3), γ = 96.972(3). The structure is characterized by 1D boron–oxygen chains composed of [B5O7(OH)4]3− polyanions that are further interspaced by Ca2+, NH4+ cations, along with lattice water molecules. The phase purity and thermal stability of the as‐synthesized sample were confirmed by XPRD and TG‐DSC analyses. Experimental UV–vis diffuse reflectance spectroscopy coupled with Urbach fitting indicates a direct bandgap of 4.50 eV, contrasting with theoretical calculations that suggest an indirect bandgap of 5.53 eV. Additionally, both theoretical computation and polarized light experimental test indicate that NH4Ca[B5O7(OH)4]·H2O exhibits moderate birefringence.

Synthesis, structural characterization, and theoretical analysis of novel zinc(ii) schiff base complexes with halogen and hydrogen bonding interactions.

In this article, we present the synthesis and characterization of three zinc(ii) complexes, [ZnII(HL1)2] (1), [ZnII(HL2)2]·2H2O (2) and [ZnII(HL3)2] (3), with three tridentate Schiff base ligands, H2L1, H2L2, and H2L3. The structures of the complexes were confirmed by single-crystal X-ray diffraction analysis. DFT calculations were performed to gain insights into the self-assembly of the complexes in their solid-state structures. Complex 1 exhibits dual halogen-bonding interactions (Br⋯Br and Br⋯O) in its solid-state structure, which have been thoroughly investigated through molecular electrostatic potential (MEP) surface calculations, alongside QTAIM and NCIPlot analyses. Furthermore, complex 2 features a fascinating hydrogen-bonding network involving lattice water molecules, which serves to link the [ZnII(HL2)2] units into a one-dimensional supramolecular polymer. This network has been meticulously examined using QTAIM and NCIplot analyses, allowing for an estimation of the hydrogen bond strengths. The significance of H-bonds and CH⋯π interactions in complex 3 was investigated, as these interactions are crucial for the formation of infinite 1D chains in the solid state.

Metal cation and crystal lattice water molecule stabilized highly mesoporous manganese oxide network for excellent durable electrode in sodium-ion storage

Potassium birnessite is a remarkable material with a wider inter-planar spacing, which enables to accommodate more electrolytic ions to improve overall electrochemical performances. In this work, controlled synthesis of K0.46Mn2O4(H2O)1.4 (HKMO) nanosheets were interconnected mesoporous networks uniformly grown on carbon cloth (CC) via a one-step hydrothermal process. Specifically, the HKMO sample synthesized at 100 °C for 12 h (100@HKMO-12 h) exhibited a mesoporous morphology with a large specific surface area. The binder-free 100@HKMO-12 h electrode exhibits a maximum specific capacitance of 255F g−1 (323F cm−3) in 1 M NaClO4/acetonitrile electrolyte over a broad potential range of 3 V. DFT studies demonstrated the interlayer distance increased by the insertion of K+ ions into the MnO2 matrix. Bader charge analysis showed a 12.09 |e| charge difference for K-birnessite in the inter-layer region compared to the normal birnessite, supported the increase of inter-layer region in the MnO2 matrix. Significantly, the increased interlayer the distance, promoted rapid intercalation/deintercalation of Na+ ions and allowed the reversible faradic pseudocapacitance reaction to occur at a wider potential window. Moreover, the symmetric full-cell fabricated utilizing the 100@HKMO-12 h electrodes have a wide voltage of 2 V and the device delivered a maximum specific energy of 43 Wh kg−1 (28 Wh cm−3) at a minimum specific power of 556 W Kg−1 (349 W cm−3). Besides, the device showed an excellent capacitance retention of ∼94 % even after 10,000 continuous charge–discharge cycles at a current of 5 A/g, indicating it is a potential candidate for next-generation sodium energy storage devices.

In-silico antibacterial activity of piperazinyl-based copper(II) metallo-organic pharmacophores

The piperazinyl-based Cu(II)-Schiff base complex {[Cu(HL1′)(N3)]2∙(ClO4)2·4H2O} (1) [HL1′ is the Zwitter ionic form of (E)-2-((2-piperazin-1-ylethylimino)methyl)phenol] was synthesized and characterized by spectroscopic and single crystal X-ray diffraction studies. The X-ray single crystal structure analysis shows that the asymmetric unit of 1 contains a four-coordinate discrete complex cation, [Cu(HL1′)(N3)]+ (1a), with a perchlorate anion and a lattice water molecule. Two square planar units of 1a are dimerized by weak Cu···N intermolecular interaction, forming [Cu(HL1′)(N3)]2 2+ (1′a). DFT and TD-DFT calculations of the monomeric cationic unit, [Cu(HL1′)(N3)]+ (1a) were performed. In-silico antibacterial activities of HL1 as well as monomeric and dimeric cationic units 1a and 1'a, respectively, were performed and study shows that 1a (EC50 0.30 μM) and 1′a (EC50 0.06 μM) may be treated as antibacterial drugs after in-vivo analysis and clinical testing.

Synthesis, spectral analysis, XRD, molecular docking simulation of dithranol and glycine mixed ligand complexes and their potential role in suppressing breast cancer cells via down‐regulating the expression of protein metalloproteinase‐9

Five novel complexes of nickel (II)(1), zinc (II)(2), zirconium (IV)(3), lanthanum (III)(4), thorium (IV)(5), with the dithranol (Dithr) ligand and glycine (Gly) were synthesized and characterized. Their structures were investigated using elemental analysis, molar conductance (Λ), magnetic studies (μeff), spectroscopic methods (FT‐IR, UV–Vis., 1H NMR, XRD), mass spectrometry, TG/DTG and DTA. Findings revealed that Dithr was chelated via two hydroxyl oxygen atoms and carbonyl group while, Gly chelated through carboxylic oxygen and nitrogen atom. All complexes appeared with molar ratio 1:1:1 (M:Dithr:Gly) and were electrolytes with 1:1 for (1), (2) and (3) complexes, 1:2 for (4) complex, and 1:3 for (5) complex according to elemental analysis and molar conductivity data. All metal‐chelates, except Th (IV)‐complex, were confirmed to have lattice water molecules based on their thermal behavior. Average crystalline size of all compounds was calculated using XRD analysis and found in the range 35.50–55.57 nm, indicating the compounds existed as nanocrystalline structure, except zirconium (IV) complex. Then, we studied cytotoxic effects of our synthetic drugs on the survival of an aggressive‐breast‐cancer‐histotype“66cl‐4.” Given its involvement in cancer‐metastasis, matrix‐metalloproteinase‐(MMP)‐9 protein expression was evaluated using western‐blotting‐assays. Th(IV)‐complex emerged as the most effective option in inhibiting cancer‐cells‐proliferation (IC50: 9.39 μM), and suppressed expression MMP‐9 levels by 86%, at 25 μM dose, and drug‐binding‐affinity was interpreted via molecular modeling.

Synthesis and crystal structure of new Mn (III) complex; a target catalyst for direct conversion of thiols after heterogenization

In this study, we are interested in the synthesizing of a new water-soluble complex of Mn (III) formulated as [Mn(pzo)(dipic)(H2O)2]2·3H2O; hereafter referred to as complex 1 where pzo− = pyrazonate and dipic2− = pyridine-2,6-dicarboxylate, under hydrothermal conditions. The molecular structure of complex 1 is primarily determined by single crystal X-ray diffraction (SC-XRD) which shows two mono-nuclear complexes of Mn (III) with three lattice water molecules. According to SC-XRD, complex 1 crystallizes in space group P1¯ of a triclinic system. The center of Mn (III) is seven-coordinated with a distorted pentagonal-bipyramidal geometry with three oxygen atoms and two nitrogen atoms in the equatorial plane. Two oxygen atoms of two water molecules are coordinated in the axial positions. In addition, the structure of complex 1 has been studied by elemental analysis (CHN), Fourier-transform infrared spectroscopy (FT-IR (, thermogravimetric analysis/differential thermal analysis/differential thermogravimetry (TGA/DTA/DTG). Complex 1 has been immobilized on the silica-coated Fe3O4 nanoparticles to produce an efficient and recyclable heterogeneous catalyst formulated as Fe3O4@SiO2@1; hereafter referred to as catalyst 1. Catalyst 1 was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), energy-dispersive X-ray spectrometer (EDS), FT-IR, scanning electron micrograph (SEM), powder X-ray diffraction pattern (PXRD), and Brunner-Emmet-Teller (BET). 1 was used as a new heterogeneous catalyst for the oxidative coupling of thiols to their corresponding disulfides using 30 % H2O2. Under optimum reaction conditions, catalyst 1 exhibited high catalytic activity. 1 can be recovered by a magnet and reused for at least 7 consecutive cycles without significant loss of catalytic performance.

Exploring the Water Oxidation Catalytic Activity of a Mn-Based Magnetic Metal-Organic Framework: The Role of Proton Conductivity and Oxygen Evolution Reaction Overpotential.

The present work evaluates the water oxidation catalytic activity of a Mn-based metal-organic framework (MOF), which we envisioned to reduce the oxygen evolution reaction (OER) overpotential because of its high electrical conductivity, facilitated by solvent-encapsulated structural features. The presence of Mn centers induces interesting magnetic features in the MOF, which exhibits impressive cryogenic magnetic refrigeration with a ΔSM value of 29.94 J kg-1 K-1 for a field change of ΔH = 5T at 2.3 K. To the best of our knowledge, the ΔSM value of the current system ranked the highest position among the published examples. The crystal structure aligns perfectly with the thematic expectations and features as many as ten metal-coordinated water molecules, forming an extensive web of a hydrogen-bonded network while facing toward the porous channel filled with another set of much-anticipated entrapped lattice water molecules. Such structural features are expected to manifest high proton conductivity, and detailed investigation indeed yields the best value for the system at 1.57 × 10-4 S/cm at 95% humidity and 85 °C. In order to evaluate the thematic notion of a one-to-one relationship between OER and improved electrical conductivity, extensive electrocatalytic water splitting (WS) investigations were carried out. The final results show highly encouraging WS ability of the Mn-MOF, showing the electrocatalytic surface area value of the active species as 0.0686 F/g with a turnover frequency value of 0.043 [(mol. O2) (mol. Mn-MOF)-1 s-1]. Another fascinating aspect of the current communication is the excellent synergy observed between the experimental WS outcomes and the corresponding theoretical data calculated using density functional theory (DFT). Consequently, a plausible mechanism of the overall OER and the role of the Mn-MOF as a water oxidation catalyst, along with the importance of water molecules, have also been derived from the theoretical calculations using DFT.

Investigation of the structure and multi-stimuli-responsive behavior of ion-associated salt solvates of binary crystals

Investigation of the intermolecular interactions and crystal packing to understand crystal growth is a prime objective of crystal engineering. Solvent molecules within crystal assist the supramolecular aggregation, however, control over their lattice incorporation remains uncertain. In this work, we report three solvates of an ionic organic salt of a diazo-naphthol sulfonate (1) and 1,10-phenanthroline with one (2), three (3) and four (4) lattice water molecules. Attempts to isolate the dihydrate form were unsuccessful, while the monohydrate of 1 has been crystallised for comparative structural investigations. Structural studies reveal the existence of intriguing sulfonate-diazo intermolecular interactions responsible for centrosymmetric dimerization of the organosulfonate 1, which also persist in 2–4, validating higher preference and robustness of the synthon. Repetitive aggregation of the sulfonate-diazo interaction in 1 leads to the formation of linear π-stacked aggregate, which further aggregates through the lattice water molecules. The structural comparison indicates the preferential formation of the organo-sulfonate dimers in hydrated salts 2–4. Further, sandwich tetramers in 2 and 4 are formed by charge transfer interaction of the organo-sulfonate dimers with pyridinium coformer on either side, which are further associated by the lattice water molecules into disparately packed 3-dimensional supramolecules. The organo-sulfonates in 3 form a similar type of extended π-stacked chains as in 1, which are flanked by pyridinium ions to form hydrogen-bonded tapes, which are helped by the lattice water molecules to grow as segregated stacked layer solid. The characteristic absorption frequency of the diazo functionality is blue-shifted in infrared spectra of the cocrystal forms, indicating the presence of charge transfer interactions. The presence of dynamic solvent and protons in the lattice makes the solid forms multi-stimuli-responsive to exhibit mechano and vapochromic response. These phenomena have been studied in detail with the help of thermal, spectroscopic, and powder-diffraction studies.

Supramolecular assembly in Cu(II) and Zn(II) compounds with pyridine and anthraquinone-1,5-disulfonate: Experimental and theoretical analysis

Two new multi-component coordination compounds of Cu(II) and Zn(II) viz. [Cu(py)2(H2O)4]ADS·2H2O (1) and [Zn(4-CNpy)2(H2O)4]ADS·2H2O (2) (py = pyridine, 4-CNpy = 4-cyanopyridine, ADS = anthraquinone-1,5-disulfonate) have been synthesized in aqueous media at room temperature and characterized using elemental and spectroscopic analyses (FT-IR, electronic), TGA and single crystal X-ray diffraction techniques. Both the compounds crystallize as metal–organic multi-component compounds containing complex cationic moieties along with uncoordinated anionic ADS moieties in the crystal structures. Crystal structure analysis of 1 reveals the stabilisation of the layered assembly of the compound assisted by CH⋯O, OH⋯O hydrogen bonding and π-stacking interactions. Antiparallel CN⋯CN and aromatic π-stacking interactions provide rigidity to the crystal structure of compound 2. In addition, enclathration of lattice water molecules within the supramolecular cavity of 2 provides additional reinforcement to the crystal structure. We have carried out theoretical investigations to analyze π-stacking, H-bonding and antiparallel CN···CN non-covalent interactions observed in the compounds using DFT calculations, quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) plot index computational tools. The binding energies of the supramolecular assemblies are quite significant due to the ion-pair nature of the interactions which lack directionality; however, the aforementioned weaker non-covalent interactions play crucial roles in the final arrangement of molecules in the solid state due to their directional nature.

Stimuli-Responsive Properties of a Zinc(II) Salen-Type Schiff-Base Complex and Vapochromic Detection of Volatile Organic Compounds.

This contribution reports, through a combined thermogravimetric analysis, differential scanning calorimetry, UV-vis, powder X-ray diffraction, and Rietveld refinement analysis, on the stimuli-responsive chromic properties of a substituted Zn(salmal) Schiff-base Lewis acidic complex with unique and distinct thermo- and vapochromic characteristics. The solid complex obtained in air or by evaporation of the solvent from their THF solutions shows a marked thermochromism associated with a phase transition, unusually triggered by the reversible desorption/adsorption of one lattice water molecule. In contrast, the anhydrous solid, achieved from THF solutions of the complex by evaporation of the solvent under anhydrous conditions, behaves very differently as it does not show any absorption of water or thermochromism and exhibits varied vapochromic properties. Detection of volatile organic compounds having Lewis basicity is demonstrated by using the anhydrous solid or the related cast films on glass or paper substrates. In both cases, a marked vapochromism is observed upon exposure to vapors of various volatile species and involves well-defined optical absorptions and naked-eye color changes, also allowing the discrimination of primary aliphatic amines. Vapochromic behavior with the formation of stable, stoichiometric adducts is also demonstrated for both the solid obtained in air and the anhydrous solid or for the related cast films after exposure to vapors of pyridine.

A New Tripodal Zwitterionic Ligand-Based Cationic Manganese(II) Metal-Organic Framework: Synthesis, Characterization and Photochromic Property

A new flexible tripodal 1,1′,1′′-(((1,3,5-triazin-2,4,6-triyl)tris(benzene-4,1-diyl))tris(methylene))tris(3-carboxypyridin-1-ium) bromide (H3taznaBr3) ligand and its new Manganese(II) compound, namely {[Mn(µ6-tazna)]Cl2·4H2O}n(OGU − 1, OGU: Osmangazi University), were synthesized and structurally characterized by IR spectroscopy, elemental analysis, X-ray single-crystal and powder diffraction techniques. Single crystal X-ray diffraction analysis revealed that the OGU − 1 is 3D framework, possessing 1D channels along the b-axis with dimensions of 9.39 × 13.63 Å2, in which 1D channels are filled with chloride ions and lattice water molecules. The OGU − 1 displayed a 6,6-connected net with a point symbol of {48.66.8}{49.66}. Furthermore, thermal (TG, DTA and DTA) and photochromic properties of the OGU − 1 were investigated and it exhibited color change under 365 nm UV light.

Synthesis and characterization of a new copper-based polyoxomolybdate and its catalytic activity for azide-alkyne cycloaddition reaction under UV light irradiation

A new organic-functionalized Cu-based Anderson-type polyoxomolybdate, namely (C7H15N4)2[Na(H2O)4]2[C6H12CuMo6N2O24]·2(H2O) (CuII-POM), was synthesized via a simple one-pot reaction and subsequently characterized using a range of analytical and spectral techniques. Structural investigation by single crystal X-ray diffraction analysis revealed that the polyanion component of the synthesized compound (i.e. [C6H12CuMo6N2O24]4−) possesses a δ-isomer Anderson-type structure, which is surrounded by four lattice water molecules and four [C7H15N4–NaH15(H2O)8]4+ cations in the crystal packing arrangement. The resulting double-sided tris-functionalized Anderson-type compound can function as highly effective heterogeneous photocatalysts for the copper(I)-catalyzed Huisgen azide-alkyne cycloaddition (Cu-AAC) reaction of terminal alkyne, benzyl halides, and sodium azide (acts as the azidonation and reducing agent) in aqueous media. Ultraviolet light irradiation enhances the catalytic activity of CuII-POM ~ 4.4 times of the “off” situation under reaction conditions of 0.00239 mmol cat., 80 °C, 8 h, 2 mL H2O, So that the isolated yields for the AAC reaction involving a variety of terminal alkynes and benzyl halides using the CuII-POM catalyst ranged between 19–97%. The current study is the first report about using an efficient and economical Cu(II)-POM/UV/NaN3 catalytic system in the Cu-AAC reaction and reveals its significant potential for applying to other Cu(I)-catalyzed reactions.

A Dawson-type {P4W24} modified using phenylphosphonic acid with excellent proton conductivity.

A case of organic-inorganic hybridized phosphotungstate modified using aromatic organophosphonic acid, K4Na4H11[KCo2(H2O)10P4W24O92{(PhPO)2}]·48H2O (1), was successfully synthesized in conventional aqueous solution. The prominent structural feature is that the total structure of [KP4W24O92{(PhPO)2}]23- resembles a V-shaped structure, which was stabilized by two [Co(H2O)5]2+ ions. Furthermore, it can be connected into a three-dimensional mesh structure using K+ ions. Surprisingly, 1 possesses a remarkably high proton conductivity of 1.59 × 10-2 S cm-1 at 95% RH and 318 K probably due to the fact that its structure contains large amounts of lattice water molecules, coordination water molecules and counter cations.

Mixed pyrazinamide and 4-dimethylaminopyridine nickel(II) complex: Characterization, DFT, and biological potentials

Ni(II) complex of pyrazinamide with 4-Dimethylaminopyridine formulated as [Ni(PZA)2(DMAMP)2](H2O) [PZA=pyrazinamide, DMAMP = 4-Dimethylaminopyridine] has been prepared and structurally elucidated using spectroscopic techniques and single crystal x-ray diffraction. The [Ni(PZA)2(DMAMP)2](H2O)X-ray structural refinement showed the PZA coordinates with the metal center Ni2+ ion as a neutral ligand in chelating with two nitrogen and two nitrogen atoms from the bidentate PZA ligand, along with two nitrogen atoms from the monodentate DMAMP moiety in a slightly distorted octahedral configuration. The findings of the X-ray analysis indicate that the product crystallizes in the tetragonal system with a=b=13.2738(5), c = 14.8262(8) Å, and space group P41212 with (α = β = γ = 90o). Thermogravimetric analysis was achieved on the sample to ascertain the thermal stability, method of thermal degradation of the complex, the existence of lattice water molecules, and the formation of the metal oxide. Additionally, antibacterial efficacy of the complex was evaluated in-vitro against 5 bacteria isolates (3 Gram + and 2 Gram -) using the agar disk diffusion method and antimycobacterial activities against three spp. of Mycobacterium tuberculosis to compare the potencies of the metal complex with the parent drug. The results revealed that the complex exhibited improved action by showing promising broad-range anti-bacterial potential compared to the ligands. The DFT studies showed that the Ni complex has an energy gap (ΔE) value of 3.025 eV in methanol, which is lower than that of the free ligands; 4.968 eV and 5.034 eV for pyrazinamide and 4-Dimethylaminopyridine respectively.

Crystallographic, theoretical and conductivity studies of two new complexes [Ni(II) and Cu(II)] based on mixed ligands approach

Two new complexes [Ni(C7H3NO5) (C15H11N3)]. 4(H2O) (1) and [Cu(C7H3NO5) (C15H11N3)]. 4(H2O) (2) have been synthesized using mixed chelating ligands [4-hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid) (C7H5NO5) and 2,2′:6′,2′′-terpyridine (C15H11N3)] in aqueous medium. The two complexes were characterized by UV–visible, IR spectroscopy as well as by single-crystal X-ray diffraction analysis. The geometries of both the complexes are distorted octahedral with N4O2 chromophore. The non-covalent interactions found in the solid state architectures of complexes 1 and 2 have been described focusing on π•••π stacking and hydrogen bonding interactions. These non-covalent interactions played an imperative role in building of multi-dimensional supramolecular architectures. These interactions have been explored theoretically by density functional theory (DFT) focusing on the antiparallel π-π stacking in self-assembled dimers and the hydrogen bonding networks mediated by the lattice water molecules. MEP surface calculations combined with QTAIM and NCI plot analysis were used to rationalize and characterize the non covalent interactions involved in the assemblies. The low optical band gaps of the two complexes exhibit semiconducting property leading to potentially fabricate Schottky Barrier Diode.

Copper coordination polymer with lattice water molecules and strong electrocatalytic OER activity

The versatility of organic ligand and metal coordination geometry produced coordination polymer with intriguing network structure and exciting functional properties. Herein, we have synthesized a copper coordination polymer (Cu-HS) using an amino acid based multidentate ligand and explored its electrocatalytic OER activity in alkaline condition. Single crystal structural studies showed the formation of 1D coordination network structure and inclusion of lattice water. Copper ions in Cu-HS displayed octahedral and square pyramidal coordination geometry. Electrocatalytic OER studies in alkaline medium showed strongly enhanced activity for Cu-HS polymer that required an overpotential of 273 mV to achieve the benchmark current density of 10 mA/cm2. Tafel slope analysis and electrochemical impedance studies suggested faster reaction kinetics at the electrode surface modified using Cu-HS. After catalysis, XPS and FTIR spectra of Cu-HS suggested the conversion to metal oxide during the electrocatalysis.

Synthesis & Spectroscopic Studies of Chalcone Ligand Chelation with Some First Transition Metal’s

Synthesis & Spectroscopic Studies of Chalcone Ligand Chelation with Some First Transition Metal’s

Understanding proton conduction enhancement of MOF-802 through in situ incorporation of imidazole into its channels

In this study, the proton-conducting properties of zirconium-based MOF-802 were investigated. MOF-802 exhibited remarkable thermal, aqueous, and acidic stabilities as well as room temperature superprotonic conduction under 98% relative humidity (RH), however, the proton conduction sharply drops above 318 K due to the release of lattice water molecules. To address this issue, a facile one-pot synthetic method was developed to encapsulate high boiling imidazole molecules in the pores/channels of MOF-802 as proton-transport medium, resulting in Im@MOF-802-S, which showed the enhanced proton conduction regarding MOF-802. We conducted a detailed discussion on the factors contributing to the improvement of the proton-conducting nature of MOF-802.

Ratiometric Fluorescence Thermometry, Quantitative Gossypol Detection, and CO2 Chemical Fixation by a Multipurpose Europium (III) Metal-Organic Framework.

A lanthanide-based molecular crystalline material endows metal-organic frameworks (MOFs) with many fascinating applications such as fluorescence detection and CO2 chemical fixation. Herein, we describe and study a multipurpose europium(III) MOF with the formula of {[Eu2(TATAB)2]·2.5H2O·2DMF}n (Eu-MOF) (where H3TATAB is 4,4',4″-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid ligand) for photoluminescence sensor matrix and CO2 chemical fixation. This Eu-MOF features 1D square channels along the c direction with a pore size of ca.14.07 Å × 14.07 Å, occupied by lattice water and DMF molecules. The obtained Eu-MOF can achieve simultaneous luminescence of the H3TATAB ligand and Eu3+ ions, which can be developed as the sensor matrix for ratiometric fluorescence thermometry. The luminescence of the Eu-MOF demonstrates an obvious color change from red to yellow as temperature rises from 303 to 373 K and the Eu-MOF has a satisfying relative sensitivity of 3.21% K-1 and a small temperature uncertainty of 0.0093 K at 333 K. Moreover, sensitive detection of gossypol was achieved with a quenching constant Ksv of 1.18 × 105 M-1 and a detection limit of 4.61 μM. A combination of the competitive absorption and photoinduced electron transfer caused by host-guest interactions and strengthened π-π packing effect synergistically between gossypol molecules and the Eu-MOF skeleton realizes the "turn-off" sensing of gossypol. Importantly, the nature of the Eu-MOF allows showing CO2 chemical fixation under mild conditions. Thus, the Eu-MOF can be utilized as a multipurpose material for ratiometric fluorescence thermometry, quantitative gossypol detection, and CO2 chemical fixation.

Synthesis, structural elucidation, Hirshfeld surface analysis and cytotoxicity studies of homometallic dinuclear Cu(II), Ni(II) and Zn(II) Schiff base complexes derived from m-phenylenediamine

A polydentate Schiff base ligand, L was synthesized via condensation reaction between o-vanillin (OVan) and trimethyl-m-phenylenediamine [(Me)MPD]. Its Cu(II), Ni(II), and Zn(II) dinuclear complexes were prepared through complexation with corresponding acetate salts. The compounds were characterized via CHN elemental analyzer, molar conductivity, magnetic susceptibility, TGA, IR, 1H and 13C NMR. The crystal structure of the ligand, L and zinc(II) complex, Zn2L2 were elucidated by using single crystal x-ray diffraction. The crystal structure of Zn2L2 showed that the two Zn(II) metal atoms serve as bridges between the two units of the ligand through ONNO donor atoms leading to the formation of a centrosymmetric cyclic dinuclear complex. Based on the single x-ray crystallography, the zinc atoms exhibit a distorted tetrahedral geometry. Hirshfeld surface analysis was performed to determine the intermolecular interactions in the crystal structures. From this analysis, it revealed that H···H interaction for L (55%) and Zn2L2 (62.7%) was the dominant intermolecular interaction in the total area of Hirshfeld surface. The ν(CN) and ν(CO) peaks in IR spectra of the ligand L appeared at 1615 cm−1 and 1255 cm−1, respectively. The peaks shifted to lower and higher frequency by Δν of 4–12 cm−1 in the complexes. The new peaks assignable to ν(MN) and ν(MO) were observed at 514–562 cm−1 and 422–436 cm−1, respectively, indicating the coordination of the metal centers to the azomethine N and phenolic O. The Cu(II) and Ni(II) complexes are paramagnetic with μeff of 1.90 and 2.89 B.M., respectively. The thermal gravimetric analysis revealed the presence of three lattice water molecules in Cu(II) complex. The cytotoxicity studies of all compounds were carried out against colon cancer cell lines (HCT116). The parent ligand was found to be less cytotoxic than its metal complexes. Cu(II) showed the highest activity with IC50 of 0.73 ± 0.21 μM, better than the standard 5-FU.