Cobalt(II)-Based 3D Coordination Polymer with Unusual 4,4,4-Connected Topology as a Dual-Responsive Fluorescent Chemosensor for Acetylacetone and Cr2O72

Highly stable Tb(III) metal-organic framework derived from a new benzothiadiazole functionalized ligand for fluorescence recognition of ascorbic acid

Because ascorbic acid (AA) is one of the basic elements to maintain the normal physiological functions of human body, it is urgent to develop a material that can achieve efficient, rapid and in-situ detection for AA. A new fluorescence organic compound 4',4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-4-carboxylic acid) (H2BTBC) based on benzothiadiazole group has been synthesized, which can detect Fe3+ ions by fluorescence turn-off effect with a detection limit of 0.015 μM, as well as recognize linear amines by fluorescence turn-on effect. Moreover, a highly stable Tb(III) metal-organic framework has been solvothermally prepared with H2BTBC, namely {[(CH3)2NH2]2[Tb2(BTBC)4]∙solvents}n (JXUST-39), which can selectively detect AA among biological fluids by fluorescence enhancement effect with a detection limit of 0.077 μM. In addition, the mechanism for JXUST-39 detecting AA is possibly the cooperative effect of absorbance-caused enhancement and charge transfer between JXUST-39 and AA. Moreover, LED lamp beads, fluorescent films and fluorescent detection test paper based on JXUST-39 were prepared to achieve portable detection via fluorescence enhancement effect.

Co(II)-coordination Complex: Fluorescence Performances and Combined with Taxotere-Hydrogels on Breast Cancer Treatment and Clinical Care

In this study, a novel coordination polymer {Co2(Oaobtc)(bpe)(H2O)4]}n (1) was synthesized under hydrothermal conditions using a hybrid ligand synthesis method, where H4Oobtc represents 2,3,3'-tricarboxylate azobenzene, and bpe represents 1,2-bis(4-pyridyl)ethylene. The obtained CP1 was characterized by elemental analysis (EA), powder X-ray diffraction (PXRD), and thermal gravimetric analysis (TGA). Fluorescence testing confirmed the excellent photoluminescent performance of compound 1, indicating its potential as a cyan-emitting fluorescent material. Hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) are natural polysaccharides known for their biocompatibility. HA/CMCS hydrogels were synthesized using a chemical synthesis method, featuring a three-dimensional network structure with interconnected pores, and an average pore size of 314.75 ± 11.25 μm. The characterization of the taxotere-loaded hydrogel was performed using infrared spectroscopy, confirming the effective encapsulation of the drug within the hydrogel. Utilizing taxotere as a model drug, a novel taxotere-loaded metal gel was synthesized, and its anticancer efficacy was evaluated. Furthermore, the influence of different pH levels on drug release rate was investigated. Finally, the encapsulation and release of taxotere in the hydrogel were studied using UV-visible spectroscopy.

Co(II) Metal-Organic Complex: Fluorescence Performances and Loaded With Drug Vitamin B2 Hydrogels Against Recurrent Oral Ulcers

A new coordination polymer (CP) based on Co(II), namely, {[Co3(L)2(4,4'-bipy)(DMA)2]·H2O}n (1) has been synthesized after reacting Co(NO3)2·6H2O with H3L ligand in the existence of N-donor ligand 4,4'-bipyridine (4,4'-bipy), via utilizing a flexible tricarboxylic acid ligand 5-((formic acid-3-sulfur)methyl)isophthalic acid (H3L) with -S-CH2- joint. Additionally, the excellent blue fluorescence properties of CP 1 were confirmed through fluorescence spectroscopy compared to the original ligand. Using natural polysaccharide hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, HA/CMCS hydrogel was prepared by chemical synthesis method. Taking vitamin B2 as the drug model, we designed and synthesized gels loaded with vitamin B2 metal framework and evaluated their efficacy in the treatment of recurrent oral ulcer.

Zinc(II)-Based Ring-and-Rod Coordination Layer as an Excitation-Wavelength-dependent Dual-Emissive Chemosensor for Discriminating Fe3+, Cr3+, and Al3+ in Water

The reactions of Zn(NO3)2, 3,6-bis(pyridin-3-yl)-9H-carbazole (bpycz), and 2,5-dihydroxyterephthalic acid (H4dhbdc) or 2-bromoterephthalic acid (Br-1,4-H2bdc) under hydro(solvo)thermal conditions yielded corresponding coordination polymers (CPs) {[Zn(H2dhbdc)(bpycz)]•0.5H2O}n (1) and [Zn(Br-1,4-bdc)(bpycz)]•2DMAc•H2O (2), respectively, with high thermal stability approaching 350 °C. CP 1 adopts a ring-and-rod layer structure, which is topologically described as a 4-connected net with the point symbol of 2•65. Two layers are interpenetrated in parallel interlocking mode to form a double 2D → 2D polyrotaxane entanglement with extra-framework void space of 19.6%. CP 2 has a non-interpenetrating ring-and-rod layer structure of 4-connected 2•65 net topology, with extra-framework void space of 16.6%. Thermally activated 1 and 2 revealed CO2 uptakes of 101.1 and 98.6 cm3 g-1, respectively, at P/P0 = 1 and 195 K. X-ray powder diffraction (XRPD) patterns confirmed that 1 and 2 both possessed high chemical stability in H2O, CH3OH, acetone, and DMF, and framework stability during gas adsorption-desorption. The H2O suspension of 1 displayed excitation-dependent dual-emissive properties, appearing at 432 nm upon excitation at 300 nm and at 528 nm upon excitation at 365 nm. Of note, 1 was capable of detection of Fe3+, Cr3+, and Al3+ ions in H2O, showing good anti-interference ability, excellent selectivity, and high sensitivity. More interesting, the dual-emissive properties make 1 to be an excellent luminescence chemosensor to screen Fe3+, Cr3+, and Al3+ from a pool of metal ions in H2O upon excitation at 300 nm via luminescence quenching effect and then discriminate Fe3+, Cr3+, and Al3+ upon excitation at 365 nm via luminescence quenching, unaltered, and enhancement responses, respectively. On the other hand, the H2O suspension of 2 demonstrated an excitation-independent emission appearing at around 430 nm, which could be utilized to sensitively detect Fe3+ and Cr3+ ions with good anti-interference ability and excellent selectivity via luminescence quenching effect. Further, 1 and 2 were recyclability and possessed cycling stability. The plausible sensing mechanisms for 1 and 2 toward Fe3+, Cr3+, and Al3+ were also explored in detail.

Synthesis and real-time monitoring of the morphological evolution of luminescent Eu(TCPP) MOFs

Real-time acquisition of the morphological information of nanomaterials is crucial to achieving morphological controllable synthesis, albeit being challenging. A novel device was designed, which integrated dielectric barrier discharge (DBD) plasma synthesis and simultaneous in situ spectral monitoring of the formation of metal-organic frameworks (MOFs). Important dynamic luminescence behaviors such as coordination induced emission (CIE), antenna effect (AE), and red-blue shift were continuously captured to reveal the spectral emission mechanism and energy transfer progress and verify the correlation with the morphological evolution of the MOFs. The prediction and control of morphology were successfully achieved with Eu(TCPP) as a model MOF. The proposed method will shed new light on exploring the spectral emission mechanism, energy conversion and in situ morphology monitoring of other luminescent materials.

Highly pH-Responsive Sensor Based on a EuIII Metal-Organic Framework with Efficient Recognition of Arginine and Lysine in Living Cells

A lanthanide-based three-dimensional metal-organic framework with excellent water, acid/base, and solvent stability, namely {[(CH3)2NH2]0.7[Eu2(BTDBA)1.5(lac)0.7(H2O)2]·2H2O·2DMF·2CH3CN}n (JXUST-29, H4BTDBA = 4',4‴-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid), Hlac = lactic acid), has been synthesized and characterized. Since the N atoms of the thiadiazole group will not coordinate with lanthanide ions, JXUST-29 has a free basic N-site accessible to small H+ ions, which allows it to be used as a promising pH fluorescence sensor. Interestingly, the luminescence signal was significantly enhanced, with an approximately 54-fold enhancement in the emission intensity when the pH value was increased from 2 to 5, which is the typical behavior of pH probes. In addition, JXUST-29 can also be used as a luminescence sensor to detect l-arginine (Arg) and l-lysine (Lys) in an aqueous solution through fluorescence enhancement and the blue-shift effect. The detection limits were 0.023 and 0.077 μM, respectively. In addition, JXUST-29-based devices were designed and developed to facilitate detection. Importantly, JXUST-29 is also capable of detecting and sensing Arg and Lys in living cells.

A water-stable dual-responsive Cd-CP for fluorometric recognition of hypochlorite and acetylacetone in aqueous media

One novel cadmium(II)-coordination polymer [Cd₃L₂(datrz)(H₂O)₃] (CP 1) is controllably synthesized by surmising the astute combination of semi-rigid tricarboxylate acid 4-(2',3'-dicarboxylphenoxy) benzoic acid (H₃L) and auxiliary ligand 3,5-diamino-1,2,4-triazole (datrz). Structure analysis shows that CP 1 has a two-dimensional (2D) layer structure with a 5-nodal (4³) (4⁴·6²) (4⁵·6⁴·8) (4⁵·6) (4⁷·6⁶·8²) topology. Further investigations reveal that CP 1 shows superordinary water stability and good thermal stability. The fluorescent explorations suggest that the as-synthesized CP 1 could emit blue light centered at 485 nm, attributing to ligand-based emission. In terms of sensing investigations, CP 1 could act as a fluorescent sensor for detecting hypochlorite (ClO^-) and acetylacetone (acac) through fluorescence turn-off process in aqueous solution, and the detection limit could reach 0.18 μM and 0.056 μM, respectively. Further research reveals that it is more likely the N-H···O-Cl hydrogen bonds between -NH₂ groups of the triazole ligands and O atoms of ClO^- plays the key role in the system, which may serve as a bridge for the energy transfer, leading to fluorescence quenching of the chemosensor. While the photoinduced electron transfer (PET) combined with inner filter effect (IFT) should be responsible for the turn-off fluorescence of CP 1 triggered by acac.

A pH-Stable TbIII-Based Metal-Organic Framework as a Turn-On and Blue-Shift Fluorescence Sensor toward Benzaldehyde and Salicylaldehyde in Aqueous Solution

A new polydentate tetracarboxylic acid with a benzothiadiazole unit (4',4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid), H₄BTDBA) has been used to prepare a pH-stable three-dimensional Tb^III-based metal-organic framework (MOF) with the formula {[(CH₃)₂NH₂]_0.7[Tb₂(BTDBA)_1.5(lac)_0.7(H₂O)₂]·solvents}_n (Hlac = lactic acid, JXUST-19). JXUST-19 exhibits a new (4,4,12)-connected topology based on tetranuclear [Tb₄] clusters. JXUST-19 can remain stable when soaked in water for at least 1 week and in aqueous solutions with various pH values (2-12) for 24 h. Fluorescence study indicates JXUST-19 can be employed as a rare turn-on and blue-shift MOF sensor toward benzaldehyde (BZ) and salicylaldehyde (SA). To date, JXUST-19 represents the first Tb^III-based turn-on MOF sensor toward salicylaldehyde in aqueous solution, and the fluorescence enhancement and naked-eye detection of BZ have been rarely reported. In addition, JXUST-19 based fluorescent test papers, light-emitting diode lamp beads, and portable composite films were developed to realize naked-eye detection of BZ and SA, which has great potential in practical applications.

Two Co(II) and Zn(II)-Related Coordination Polymers: The Diversity of Structure and Treatment Activity on Orthodontic Root Resorption Repair

Co(II)- and Zn(II)-related coordination polymers (CPs): [Co(OPBT)(GA)]n (1) and {[Zn2TTPA(GA)2] · 2H2O}n (2), where TTPA represents tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine) and OPBT represents 1.1′-(oxybis(1,4-phenylene))bis(1H-1,2,4-triazole), were prepared through mixed-ligand synthesis. The raw materials were flexible glutaric acid (H2GA) with Co(II)/Zn(II) nitrate salts, TTPA, and bi- and tritopic 1,2,4-disparate triazole derivatives. The application value of the CPs in orthodontic root resorption repair was evaluated, and their relevant mechanisms were explored. ELISA assay was used in determining the content of tumor necrosis factor-α released in the gingiva groove. Then, real time RT-PCR was utilized in assessing whether the nuclear factor kappa-B inflammatory activity was activated. Additionally, the CCK-8 method was used in investigating positive effects on osteoblast proliferation. Finally, the expression of the wnt protein in osteoblasts was detected with Western blotting assay.

Two coordination polymers: Crystal structures, prevention and nursing values on postoperative infection

In this current work, two fresh transition metal coordination polymers (CPs) have been created with the reaction between terphenyl-3,3″,5,5″-tetracarboxylic acid (H4L), the symmetrical rigid carboxylic acid ligand and the relevant metal salts under the reaction conditions of solvothermal, and the chemical compositions of the compounds respectively are {[Cu2(TPTC) (DMF)2(H2O)]·2DMF·2H2O} (2) and {[Zn (TPTC) (1,2-bimb)2]·4(H2O)}n (1, bimb = 1,2-bis((1H-imidazol-1-yl)methyl)benzene). Moreover, the prevention and nursing values of the compound on postoperative infection was explored and their corresponding mechanism also was investigated. Firstly, enzyme linked immunosorbent assay kit (ELISA) was employed to detect the release of inflammatory cytokines into plasma. Additionally, the expression of the bacterial survival genes was determined via exploiting the real time reverse transcription-polymerase chain reaction (RT-PCR) after treated with the compound.

A hydrostable CuII coordination network prepared hydrothermally as a "turn-on" fluorescent sensor for S2- and a selective adsorbent for methylene blue

The effective monitoring of water pollution and further purification are pressing yet challenging issues for guaranteeing the health of human beings and the stabilization of ecological systems. For this purpose, the development of efficient sensing and adsorption materials as a result of supramolecular interactions, including coordination and H-bonding etc., have been attracting increasing attention. With the aid of a coordination-driven self-assembly strategy, a new nonporous 2D CuII coordination network, [Cu2L(H2O)2]n (donated as CuCP), based on H4L, where H4L = 4-(4-(3,5-di-carboxy-pyridin-4-yl)phenyl)pyridine-2,6-dicarboxylic acid, was afforded hydrothermally. Structural analysis indicated that CuCP featured a wrinkled network similar to the ancient Chinese folding screens and constructed by the fully deprotonated ligand L4- with the coordination mode of bis(μ2-η1:η1:η2) and penta-coordinated Cu2+, which could be further upgraded to a supramolecular 3D framework as a result of the synergism of multiple C-H⋯O hydrogen bonds. The hydrostability of CuCP could be maintained within a wide pH range from 2 to 12 as verified by PXRD determination, endowing it with potential environmental applications. Thanks to the combination of the soft Lewis acidity of Cu2+ and its large conjugated structure, CuCP could be used as a turn-on fluorescence sensor for S2- and exhibited a different fluorescence response when Na2S, (NH4)2S or H2S were incorporated, even in actual water samples. The sensing mechanisms were disclosed in detail by the combination of experiments and density functional theory (DFT) calculations. Furthermore, CuCP was shown to be a selective and recoverable adsorbent with a maximum adsorption capacity of 379 mg g-1 in 60 minutes for methylene blue (MB). The adsorption mechanism could be a combination of π⋯π stacking, n⋯π interaction, aggregation effects and Soft and Hard Acid-Base theory (HSAB). The results presented herein open up new perspectives for CuII species in environmental applications.

Luminescent binuclear Zinc(II) organic framework as bifunctional water-stable chemosensor for efficient detection of antibiotics and Cr(VI) anions in water

To achieve the ultrastable LMOFs with predominant luminescent sensing performances, the aromatic π-electron mixed ligands strategy was introduced, and the ternary LMOF of {[Zn₂(HDDB)(bib)_1.5]·3H₂O}_n (1), was fabricated based on 3,5-di(2',4'-dicarboxylphenyl)benozoic acid (H₅DDB) and the N-donor of meta-bis(imidazol-1-yl)benzene (bib) under mixed solvothermal condition. LMOF 1 features the first reported 3D 3,4,4-c {6².8³.10}{6².8}₂{6³.8².10}₂ framework with 21.2 % porosity as well as high thermal and chemical stability. Further luminescent sensing showed that LMOF 1 as a bifunctional chemosensor possessing predominant detectability for sensitive detect the hexavalent chromates and nitroimidazoles/nitrofurans antibiotics in water through strong luminescent quenching effects, with excellent reusability as well as trace detection limits. Moreover, luminescent quenching mechanisms were further investigated from electron transfer and energy transfer viewpoints.

A Water-Stable 2-Fold Interpenetrating cds Net as a Bifunctional Fluorescence-Responsive Sensor for Selective Detection of Cr(III) and Cr(VI) Ions

Reactions of ZnSO₄∙7H₂O, N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide (NI-mbpy-34), and 5-bromobenzene-1,3-dicarboxylic acid (Br-1,3-H₂bdc) afforded a luminescent coordination polymer, [Zn(Br-1,3-bdc)(NI-mbpy-34)]_n (1), under hydro(solvo)thermal conditions. Single-crystal X-ray structure analysis revealed that 1 features a three-dimensional (3-D) 2-fold interpenetrating cds (or CdSO₄) net topology with the point symbol of (6⁵·8), where the Zn(II) centers are considered as 4-connected square-planar nodes. X-ray powder diffraction (XRPD) patterns and thermogravimetric (TG) analysis confirmed that 1 shows high chemical and thermal stabilities. Notably, 1 displayed solvent dependent photoluminescence properties; the fluorescence intensity and emission maximum of 1 in different solvent suspensions varied when a solvent was changed. Furthermore, the H₂O suspension of 1 exhibited blue fluorescence emission and thus can be treated as a selective and sensitive fluorescent probe for turn-on detection of Cr³⁺ cations through absorbance caused enhancement (ACE) mechanism and turn-off detection of Cr₂O₇²⁻/CrO₄²⁻ anions through collaboration of the absorption competition and energy transfer process, with limit of detection (LOD) as low as μM scale.

Stable bifunctional ZnII-based sensor toward acetylacetone and L-histidine by fluorescence red shift and turn-on effect

A new coordination polymer [Zn(bbip)(NH2-BDC)]n (JXUST-15, bbip = 2,6-bis(benzimidazol-1-yl)pyridine and NH2-H2BDC = 2-aminoterephthalic acid) has been synthesized by mixed ligand strategy. The structure analysis shows that JXUST-15 takes a two-dimensional...

Lanthanide-based metal-organic framework materials as bifunctional fluorescence sensors toward acetylacetone and aspartic acid

A family of novel lanthanide-based metal-organic frameworks (Ln-MOFs) with bifunctional fluorescence sensing, namely {[(CH3)2NH2]5[Ln5(TBAPy)5]•solvent}n (Ln = Gd (1), Tb (2), and Dy (3), H4TBAPy = 1,3,5,7-tetra(4-carboxybenzene)pyrene), have been synthesized and...

Two chemically robust Cd(II)-frameworks for efficient sensing of levofloxacin, benzaldehyde, and Fe3+ ions

Two luminescent Cd(II)-organic frameworks [Cd2(L1)(tdc)2(H2O)]n (1) and [Cd(L2)0.5(tdc)]n (2) (L1 = 1,5-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L2 = 1,6-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane, and H2tdc = 2,5-thiophenedicarboxylic acid) were hydrothermally synthesized and characterized. 1 displays a rare binodal (3,4)-connected 2D cem-d network, while 2 exhibits a 3D mog (moganite) framework. The two MOFs are highly thermally durable and water-stable in a wide pH range from 3 to 12. Interestingly, 1 and 2 represent the first reported examples of multi-responsive probes based on MOFs for selectively detecting levofloxacin, benzaldehyde, and Fe3+ ions with reusability. The luminescence sensing mechanisms of the two CPs were explored in detail.

Magnetic Property and Therapeutic Effect of a New Co(II) Complex on Liver Cancer by Regulating the Expression of miRNA31

Employing the flexible hexacarboxylate ligand of 1,3,5-triazine-2,4,6-triamine hexaacetic acid (H6TTHA) to assemble with Co(NO3)2·6H2O, we have acquired a novel coordination compound, i.e., [Co2(H2TTHA)(H2O)]n·6n(H2O) (1). The analysis of single X-ray diffraction indicated that the H2TTHA2- ligand μ5-bridges connected the Co(II) ions into a two-dimensional layered architecture. Moreover, the magnetic property of 1 was also investigated between 2 and 300 K under 1000 Oe applied magnetic field. The novel compound’s inhibitory activity against the viability of cancer cell was determined through CCK-8 assay, and the expression of miRNA31 in liver cancer cells was detected via the real-time RT-PCR.

Tetraphenylpyrazine-Based Manganese Metal-Organic Framework as a Multifunctional Sensor for Cu2+, Cr3+, MnO4-, and 2,4,6-Trinitrophenol and the Construction of a Molecular Logical Gate

A tetraimidazole-decorating tetraphenylpyrazine has been designed and utilized for the fabrication of a novel metal-organic framework (MOF), denoted as {Mn(Tipp)(A)₂}_n·2H₂O (TippMn, where Tipp = 2,3,5,6-tetrakis[4-[(1H-imidazol-1-yl)methyl]phenyl]pyrazine and A = deprotonation of 1,4-naphthalenedicarboxylic acid), through hydrothermal synthesis. Structural analysis reveals that TippMn possesses a 2-fold-interpenetrated 4,8-connected three-dimensional (3D) network with an unprecedented {4¹⁶·6¹²}{4⁴·6²} topology. Fluorescent spectral investigations indicate that TippMn shows discriminative fluorescence when treated by Cr³⁺ and Cu²⁺, giving an INHIBIT logical gate performance. Meanwhile, TippMn can be further used as a sensor for MnO₄^- and 2,4,6-trinitrophenol (TNP) by fluorescence quenching. Notably, the sensing processes toward Cu²⁺, Cr³⁺, MnO₄^-, and TNP are labeled with high selectivity and sensitivity, quick response, and good recyclability. It is anticipated that this MOF-based versatile sensor could shed light on the exploration of MOFs for fluorescent sensors, optical switches, etc.